Manual [13]2015

TABLE OF CONTENTS

CHEMISTRY 2231 LABORATORY SCHEDULE

LAB

PERIOD EXPERIMENT PAGE

1

2

3

4

5

6

7

8

9,10

11,12

13

14

GENERAL INFORMATION ................................................................... 4

MELTING POINT ................................................................................ 12

RECRYSTALLIZATION ......................................................................... 16

DISTILLATION .................................................................................... 20

RESOLUTION OF RACEMIC PHENYLSUCCINIC ACID ............................. 23

SYNTHESIS OF TERTIARY BUTYL CHLORIDE ......................................... 26

SYNTHESIS OF 2-METHYL-2-BUTENE .................................................. 29

SYNTHESIS OF 2,4,4-TRIMETHYL-2-PENTENE AND ISOMER ................. 32

OXIDATION OF CYCLOHEXENE TO ADIPIC ACID .................................. 35

SYNTHESIS OF 2-METHYL-4-HEPTANONE ........................................... 38

SYNTHESIS OF ETHYL IODIDE ............................................................. 43

CHECK OUT ....................................................................................... 46

ORGANIC POLYMERS ......................................................................... 47

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TABLE OF CONTENTS

CHEMISTRY 2241 LABORATORY SCHEDULE

LAB

PERIOD EXPERIMENT PAGE

1

2

3

3

3

4

5

4

6

7

8

9

9

10

11

12

13

14

GENERAL INFORMATION ................................................................... 4

COLUMN CHROMATOGRAPHY .......................................................... 52

SYNTHESIS OF 1,4-DI-T-BUTYL-2,5-DIMETHOXYBENZENE ................... 55

THE CANNIZZARO REACTION ............................................................. 58

PART I ............................................................................................... 59

PART II .............................................................................................. 59

PART III ............................................................................................. 60

SPECTROCOPY ................................................................................... 62

SYNTHESIS OF BENZOPHENONE OXIME ............................................. 67

THE REARRANGEMENT OF BENZIL ..................................................... 70

PREPARATION OF METHYL BENZOATE ............................................... 73

SYNTHESIS OF LIDOCAINE .................................................................. 77

Parts I & II ......................................................................................... 78

Part III ............................................................................................... 79

SYNTHESIS OF DIBENZALACETONE ..................................................... 85

-D-(+)-GLUCOSE PENTAACETATE ...................................................... 88

CHECK OUT ....................................................................................... 91

THE SYNTHESIS OF ASPIRIN ............................................................... 92

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USEFUL INFORMATION

SAFETY ............................................................................................. 4

GRADING .......................................................................................... 5

LABORATORY NOTEBOOK ................................................................. 5

USING THE BALANCES ....................................................................... 6

HEATING IN THE LAB ......................................................................... 6

BUNSEN BURNERS ............................................................................ 7

DISTILLATION TECHNIQUE ................................................................. 7

REFLUX TECHNIQUE .......................................................................... 8

RECRYSTALLIZATION TECHNIQUE ...................................................... 8

FILTERING AND DRYING SOLID: ......................................................... 8

FILTER AID ........................................................................................ 9

DRYING ORGANIC LIQUIDS (THE REMOVAL OF WATER) ..................... 9

DRYING GLASSWARE ......................................................................... 9

USES OF THE SEPARATORY FUNNEL: .................................................. 9

THEORETICAL YIELD .......................................................................... 10

PERCENTAGE YIELD ........................................................................... 11

HANDING IN PRODUCTS .................................................................... 11

Figure 1. Recrystallization technique (diagrammed). ......................... 95

Figure 2. Reflux Set-up. .................................................................... 96

Figure 3. Simple Distillation Set-up. .................................................. 97

Figure 4. Unpacked Column Distillation Set-up. ................................ 98

4

GENERAL INFORMATION

SAFETY

SAFETY IS THE NUMBER ONE PRIORITY. Always read and understand the

experiment before coming to lab. Follow the procedure and the directions of the

instructor exactly. If you do not understand what you doing, stop and ask the instructor.

Some of the laboratory rules and regulations are:

YOU MUST:

WEAR SAFETY GOGGLES AT ALL TIMES.

WEAR APPROPRIATE CLOTHING, NO SHORTS OR SANDALS.

WORK ONLY DURING SCHEDULED LAB PERIODS.

KNOW WHAT YOU ARE DOING AT ALL TIMES.

BE ALERT AT ALL TIMES.

NO MATTER HOW MINOR, REPORT ALL ACCIDENTS.

KNOW THE LOCATIONS OF THE SAFETY EQUIPMENT.

KEEP YOUR WORK SPACE AND THE HOODS CLEAN.

YOU MUST NOT:

EAT, DRINK, OR SMOKE IN THE LAB.

PERFORM UNAUTHORIZED EXPERIMENTS.

ACT IN A LOUD OR DISRUPTIVE MANNER.

REMOVE ANY CHEMICALS OR EQUIPMENT FROM THE LAB.

IN ADDITION:

CONTACT LENSES SHOULD NOT BE WORN IN THE LAB

DO NOT PUT ANY SOLIDS IN THE SINKS, THIS INCLUDES

BOILING CHIPS, RUBBER BANDS, AND BROKEN GLASS.

ALL IRONWARE AND HOSES MUST BE RETURNED TO THE SIDE

DRAWERS AFTER EACH LAB, IN THE CORRECT DRAWER.

DISCARD ALL CHEMICALS AS DIRECTED BY YOUR INSTRUCTOR.

VISITORS ARE NOT ALLOWED IN LAB.

DO NOT START AN EXPERIMENT OVER WITHOUT YOUR INSTRUCTOR'S

PERMISSION.

EACH STUDENT IS EXPECTED TO CONCENTRATE ON THEIR OWN

WORK AND NOT CARRY ON CONVERSATIONS WITH THEIR

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NEIGHBORS. ANY QUESTIONS ARE TO BE DIRECTED TO THE

INSTRUCTOR.

IF A STUDENT HAS TO LEAVE THE LABORATORY FOR SOME

REASON, PERMISSION MUST BE OBTAINED FROM THE

INSTRUCTOR FIRST.

NEVER RETURN EXCESS CHEMICALS TO THE CONTAINER, PASS THEM

ON TO THE NEXT PERSON OR PROPERLY DISPOSE OF THEM. PUT TOPS

ON CONTAINERS IMMEDIATELY AFTER USE. THE TOPS ARE NOT USED

FOR ANYTHING ELSE, DON'T PUT CHEMICALS IN THEM.

STOP AND CLEAN UP IMMEDIATELY ANY SPILLAGE.

CLOSE THE ICE MACHINE DOOR AFTER YOU TAKE THE ICE.

SAFETY IS ALWAYS THE NUMBER ONE PRIORITY.

GRADING

The laboratory grade will count 25 % of the final Organic Chemistry lecture grade.

The laboratory grade is based on the experiments (each worth ten points), quizzes, and

notebook. The experiments are graded on the basis of the quality and quantity of the

product, and your technique. All experiments will count towards the final laboratory

grade; no experiments will be dropped. If you miss an experiment, speak with your

instructor as soon as possible, otherwise a grade of zero will be given for that experiment.

LABORATORY NOTEBOOK

Learning how to keep a proper lab notebook is part of your scientific training and you

will be expected to maintain a lab notebook for this Organic lab course. Part of your final

lab grade will be based on the adequacy of this notebook. A small bound composition

notebook (9 3/4 X 7 1/2 inches) is required. It will be graded during the semester and/or

collected at the end of the semester. It should be kept up to date at all times. Folders or

spiral notebooks are not acceptable. The notebook must include the following

information on numbered pages, unless specified differently by your instructor:

1) Start each new experiment on a new page.

2) Write the title of the experiment and the date it is preformed.

3) Write the balanced equation.

4) List the reactants, including the number of grams and moles of each. A reactant is any

reagent to the left of the arrow in the balanced equation.

5) Calculate the theoretical yield, showing all calculations.

6) Briefly outline the procedure.

7) Copy the class notes, including precautions and changes.

8) Record your results, including your actual yield and percent yield.

6

Steps one through six should be done before coming to class. Step seven

is written at the start of class and step eight is entered into your notebook

at the end of the experiment.

USING THE BALANCES

1) Start with the balance reading 0.00, press tare if it is not reading 0.00. The letter "g"

(grams) should always appear on the upper left hand of the display.

2) Place a large piece of paper and a beaker on the balance (always weigh solids in a

beaker, the paper is there in case you spill a chemical, it will be caught by the paper and

not corrode the pan of the balance).

3) Press tare so that balance again is reading 0.00.

4) Add the solid to be weighed out into beaker until desired weight is displayed.

5) Stop and clean up any spills immediately.

6) Never return excess chemicals to the container, pass them on to the next person or

dispose of them properly. Put tops on the containers immediately after use. The tops are

not used for anything else, don't put chemicals in them.

7) Remove the beaker, press tare to return balance to 0.00.

HEATING IN THE LAB

You will be required to use flask heaters, or a Bunsen burner flame as a heat

source throughout the two semesters of Organic Chemistry Lab. Read the procedures and

precautions for each experiment, to determine which heat source is necessary for that

experiment. If a Bunsen burner flame is to be used, make sure that no flammable

material, such as, solvents is in your hood. Also, make sure clothing (for example, shirts,

sweaters, and ties) and long hair, especially if you lean over, are kept away from the

flame. Never heat anything in a completely closed system.

7

BUNSEN BURNERS

1) Attach a hose from the Bunsen burner to the gas outlet (indicated by a blue color)

2) Adjust the bottom valve of the Bunsen burner so that it is open slightly.

3) Turn the gas on.

4) Using the gas lighter, light the Bunsen burner. If the burner will not light, open the

bottom valve of the burner or the gas outlet valve a little more.

5) After the burner is lit, turn the bottom valve to adjust the height of the flame and rotate

the barrel of the burner to adjust the flame size and intensity.

6) Always turn the Bunsen burner off by using the gas outlet. Always use a wire gauze

when using a flame as a heat source.

FLASK HEATERS

Never plug the Flask Heaters directly into an outlet, always use a Heat Control, which is

plugged into an outlet. Usually a setting of 15 is sufficient to heat most reaction mixtures

to boiling. Do not get the flask heater wet.

DISTILLATION TECHNIQUE

1) Always use a boiling chip, never add a boiling chip to a hot liquid.

2) Distill slowly, 1-2 drops per second.

3) The distillation receiver is always a round bottom flask.

4) All glass joints must fit tightly together, use rubber bands.

5) The tip of the temperature probe should be positioned properly (see page 95).

6) When collecting an organic product, the entire distillation apparatus must be dry.

7) Cooling water for the condenser, enters at the lower end of the condenser and exits at

the top. Use a reasonable, low pressure rate of water flow.

8) Distillation products to be submitted for grading must be dry (not cloudy). If the

product is cloudy, dry it with a drying agent and then decant the product into a dry bottle

before handing it in to the instructor.

9) Never leave a distillation unattended.

8

REFLUX TECHNIQUE

Reflux (see Figure 2, p. 95) is a method used to heat a reaction mixture to its boiling

point without losing any of this mixture through evaporation. The heat

provides the energy necessary for product formation. A good rate of reflux is

a mixture that is gently boiling, with vapor condensing no faster than 1

drop/second from the condenser. Follow the same rules as if distilling.

(boiling chips, grease, etc.) Vapors should never reach more than one quarter

of the way up the condenser. If vapors go higher in the condenser or come out

the top of the condenser, remove the heat source immediately.

RECRYSTALLIZATION TECHNIQUE

1) Steps one and two (see Figure 1, p. 94) should be set up before starting the

recrystallization process.

2) In a beaker add two boiling chips, the solid to be recrystallized, and the minimum

amount of solvent or in the amount directed. The minimum amount of solvent is the

amount of solvent that will dissolve the solid at the boiling point of the solvent, plus

approximately 10%.

3) If directed, let the liquid cool for two minutes and add a spatula full of charcoal, then

heat the mixture back to boiling. The charcoal is used to remove impurities.

4) Filter the mixture through a pre-heated powder funnel to remove any undissolved

impurities and the charcoal. The mixture that is being filtered must remain at or just

below its boiling point during the entire filtration. If solid starts to recrystallize in the

powder funnel, notify the instructor. Use a "Hot Hand" to grab the hot beaker.

5) Cool the collected liquid in an ice/water bath (use approximately 50% ice and 50%

water) until the entire contents of the beaker is ice cold (feel the outside of the beaker).

Occasionally stir the cooling solution.

6) Vacuum filter the cold mixture, rinsing the beaker with the filtrate if necessary, and

save the purified solid.

FILTERING AND DRYING SOLID:

1) Make sure the filtration apparatus is set-up as shown on p. 94, Figure 1, step 4.

2) Turn on the vacuum and mat down the filter paper with the solvent you are using

before starting to filter.

3) When beginning to filter, make sure that there is a proper seal between the funnel and

the filter flask by pushing down on the funnel.

9

4) When all of the liquid has filtered into the filter flask, it is usually a good idea to press

down the solid in the funnel with a clean cork or large spatula.

5) When finished filtering then close the vacuum.

6) Remove the solid from the filter paper and store it in a large beaker.

FILTER AID

This is a solid that sits on the filter paper and acts as a barrier to protect the filter paper

from the solid to be filtered out. It is used because the compound to be filtered consists

of very small particles that would clog up or go through the filter paper.

DRYING ORGANIC LIQUIDS (THE REMOVAL OF WATER)

A drying agent (ex. sodium sulfate) is a solid that removes water from an organic

liquid. The organic liquid is dry if it is clear and some of the drying agent swirls freely.

Start by adding a small spatula full of the drying agent to the liquid to be dried. If the

liquid is cloudy or all of the drying agent clumps together or sticks to the Erlenmeyer

flask, then there is still water present and more drying agent is needed. Add another

spatula full. The drying of an organic liquid should always be done in a stoppered

Erlenmeyer flask, not in a beaker. Always put the top back on the drying agent bottle

immediately after use.

DRYING GLASSWARE

1) Use the plastic squeeze bottle with acetone located at the front desk.

2) Squeeze acetone through the equipment needed to be dried and collect it in a beaker

(place this used acetone in the recycling container). This washes out the water.

3) Using an air jet (indicated by an orange color), gently blow air through the piece of

equipment so that the acetone evaporates. It should only take 10-15 seconds to evaporate

the acetone.

USES OF THE SEPARATORY FUNNEL:

1) To mix reagents.

2) To separate a liquid from another insoluble liquid.

3) To add a reagent dropwise to a reaction mixture.

Always remove the hollow stopper before dispensing any liquid from the separatory

funnel. In addition, drain the bottom layer and pour the top layer from the funnel.

10

THEORETICAL YIELD

The theoretical yield (TY) of a reaction is calculated before the start

of the experiment so that the student can know how much product to expect if

100 % of the reactants react to give the desired product. The calculation of

the theoretical yield can be performed in the following three steps:

1) Balance the equation.

2) Calculate the number of moles for each reactant using the following formula:

moles = grams / molecular weight

3) Calculate the TY based on each reactant using the following equation:

TY = (moles of reactant) (MW of product) {(moles of product)/(moles of reactant)}

The last term in this equation, the ratio {(moles of product)/(moles of reactant)} is

obtained from the coefficients of the balanced equation.

EXAMPLE

What is the theoretical yield of ethyl iodide given the following information:

The procedure calls for the addition of 7.9g of ethanol, 1.4g of phosphorus, and 10g of

iodine.

STEP 1: The equation is already balanced.

STEP 2: Calculate the number of moles for each reactant. Only compounds to the left of

the reaction arrow are reactants. Calculating the number of moles of ethanol,

phosphorus, and iodine:

Moles of ethanol = 7.90 / 46.07 = 0.171 moles

Moles of phosphorus = 1.40 / 30.97 = 0.0452 moles

Moles of iodine = 10.00 / 253.81 = 0.03940 moles

6CH3CH2OH 2P + 3I2+ + H3PO3I6CH3CH2Ethanol Ethyl iodide

11

STEP 3: Calculation of the TY based on ethanol:

TY = (0.171) (155.97) (6/6) = 26.6g of ethyl iodide

Calculation of the TY based on phosphorus:


Calculation of the TY based on iodine:


The correct TY is the lowest number of grams calculated in step 3, therefore, the limiting

reagent for this reaction is iodine and the correct TY for ethyl iodide is: 12.29g

PERCENTAGE YIELD

The percentage yield (%Y) is calculated at the end of the experiment to

show the student how well he or she performed the experiment and about the

limitations of the experiment imposed by the nature of the reaction.

Calculate the percentage yield using the following equation:

%Y = (Actual Yield)/(Theoretical Yield) x 100

HANDING IN PRODUCTS

Unless otherwise instructed, the product prepared is given to the instructor in a labeled

bottle or envelope. On the label is neatly printed the student's name, the name of the

product, the actual yield, and the percent yield.

12

MELTING POINT

INTRODUCTION

The melting point and the freezing point can be defined as the temperature at which a

liquid and a solid phase of a compound exist in equilibrium at a pressure of one

atmosphere. The purpose of this experiment is to gain experience in the use of the mel-

temp apparatus and to learn what useful information melting points can tell us. Organic

chemist use this physical constant for two important reasons. Because it is highly

unlikely that two substances would have the exact same melting point, the possible

identity of an unknown pure solid can be determined by simply taking its melting point.

The second reason why chemists use melting points is to determine if a substance is pure

or impure. A pure substance will have a sharp narrow range (2-3C) melting point,

while an impure substance will have a lower, wider range melting point.

Throughout both semesters of organic chemistry lab, students will be synthesizing

different solid compounds. One method to determine if the correct compound has been

synthesized and that the purity of this compound is acceptable is to take a melting point.

The student will be asked to take a melting point, before submitting certain products that

they make in future labs, therefore, learning the correct method to determine the melting

point now, will save you a lot of time and aggravation in the future.

A mixed melting point is a method used to positively identify an unknown solid.

This is done by mixing your unknown compound with a known compound that you think

could be your unknown. If the unknown and the known that you mixed with it are the

same compound, then you will get a sharp melting point range, identical to the melting

point of the unknown taken by itself. However, if you mixed your unknown with a

known compound that is different from your unknown, you introduced an impurity into

your unknown and the melting point will be lower and have a wide range. A good

example of this last fact is that salt (the impurity) is placed on icy roadways (the ice is

assumed to be pure and will melt at 0) to melt the ice because the ice will now melt at a

lower temperature.

PRECAUTION - parts of the DigiMelt apparatus are hot and will easily burn you.

13

HOW TO TAKE A MELTING POINT

1) Place a small amount of a sample into a capillary tube that is open only at one end.

Either by gently tapping the capillary tube on the bench top or by gently vibrating the

tube with a file, allow the sample to travel to the closed end of the tube. There should be

approximately 5 mm. of sample in the capillary tube, just enough to see it clearly.

2) Turn the switch on the DigiMelt apparatus to the "on" position.

3) The START temperature should read at least 30 below the melting point of the

sample.

4) The STOP temperature should be 10C above the melting point.

5) The rate of heating called the RAMP rate should be 2C / minute.

6) Record the melting point range of your sample. The low end of this temperature range

is when the sample first starts to melt and the high end is when all of the sample has

melted.

PROCEDURE

1) Before class, record the literature melting points for all the compounds listed on the

back of the Melting Point Data Sheet. Record the source of this information.

2) Take the melting point of any three known compounds that are found under the hood.

Record all of your results in your notebook and then on the Melting Point Data Sheet.

3) Take the melting point of the unknown that was given to you. Set the START at

80C, the STOP at 170C RAMP rate at 10C / minute.

4) Take a second, more accurate melting point of your unknown by setting, the START

temperature should read at least 30 below the melting point of the sample the STOP

temperature should be 10C above the melting point the rate of heating called the RAMP

rate should be 2/ minute. Repeat this step with a new sample of your unknown to verify

your results.

5) Take a mixed melting point by placing a small amount of unknown on your watch

glass and adding about 1/5 as much of a known compound. This known compound

should hav

5). Mix them well and take its melting point. Do as many mixed melting points as

needed to identify your unknown, but at least two mixed melting points should be done.

6) Write your results in your notebook and then on the data sheet which will be

submitted to your instructor.

14

NAME_________________________

Pre-lab

LITERATURE MELTING POINTS OF SOME

ORGANIC COMPOUNDS

COMPOUND LITERATURE MELTING POINT, C

Acetanilide __________

Fluorene __________

Benzoic Acid __________

Benzamide __________

Urea __________

Glucose Pentaacetate __________

Phenacetin __________

Benzoin __________

o-Chlorobenzoic Acid __________

Anthranilic Acid __________

Benzilic Acid __________

Adipic Acid __________

Salicylic Acid __________

Benzanilide __________

Source________________________________________________________

15

NAME_________________________ LOCKER NUMBER _______

DATE ________________ LAB DAY AND TIME ______________

MELTING POINT DATA SHEET

Results of Three Known Compounds listed in the Table on the Back

Results of Unknown

Unknown M.P. Range (taken quickly) _______________

Unknown M.P. Range (taken slowly) 1)_______________

2)_______________

Results of Mixed Melting Points

UNKNOWN NUMBER __________

NAME OF UNKNOWN ____________________________

GRADES: Pre-Lab (20):_____ Experimental Technique (30):_____

Yield & Purity (30):_____ Post Lab Questions (10):_____ Lab Report Grade = _____

Known Compound Literature M.P. Observed M.P. Range

Compound Mixed with Unknown Observed M.P. Range

16

RECRYSTALLIZATION

INTRODUCTION

The purpose of this lab is to learn the technique of recrystallization and how to choose

a recrystallization solvent. Recrystallization is a process used to purify solid

compounds. In addition you will identify your unknown based on melting point.

In future experiments, you will be synthesizing different solid compounds. To assure

yourself and your lab instructor that these compounds are pure, you will be required to

perform a recrystallization at the end of each lab, before handing in your product for

grading. Therefore, it is important that you understand this technique and have this

procedure written down in your notebook so that you can refer back to it when necessary.

Before we look at recrystallization in detail, it is necessary to define the term

solubility. Solubility is the extent to which a substance (called a solute) mixes with a

liquid (called a solvent) to produce a homogeneous system (called a solution). The

importance of solubility can be seen in every experiment preformed in this class and in

many aspects of every day life. Reactants, used in future experiments, will be dissolved

in a suitable solvent. This lowers the activation energy so that the reaction can proceed to

products more easily. Solubility also plays an important roll in both chromatography

experiments. Pharmacy students, in future courses, will learn that drugs taken orally need

to be water soluble and fat-soluble at the same time for optimal adsorption in the blood.

The first part of today's experiment deals with the solubility of a pure solid compound

in a wide range of polar and nonpolar solvents (the compounds in the chart of the Data

Sheet are in increasing polarity order). The degree of solubility is important to determine

a good recrystallization solvent for this solid if it needs to be purified. The definition of a

good Recrystallization Solvent is:

1) A solvent that will dissolve a large amount of the solute (the compound to be purified)

when the solvent is hot and only a very small amount of solute when the solvent is cold.

2) Impurities will not dissolve in hot or cold solvent.

3) Ideally the solvent should also be cheap, nontoxic, and nonflammable.

In the second part of this experiment you will recrystallize an impure solid compound

using the best recrystallization solvent. The two unknowns are either benzoic acid or

acetanilide. The recrystallization process can be summed up as follows. The solid to be

purified is dissolved in a minimum amount of boiling solvent. The boiling mixture is

filtered to remove all insoluble impurities. The filtrate (the liquid that was collected after

the filtering) is cooled to precipitate the solid. The solvent is filtered off, leaving the

purified solid. One can see that recrystallization works because most compounds are

more soluble in hot solvent than in cold solvent. Finally the melting point can be used to

determine if your unknown is benzoic acid or acetanilide.

17

PROCEDURE

To prepare for this experiment properly, read how to use the balances (page 5),

filtering and drying solids (page 8) and the recrystallization technique (pages 7 and 93).

PART 1: SOLUBILITY TEST FOR THE SOLID TO BE PURIFIED

KEY:

S = soluble (all solid dissolves in 3 mL of solvent)

I = insoluble (not all solid dissolves in 3 mL of solvent)

1) Before lab, record on the Solubility Data Sheet, the literature boiling points for the

solvents used in this experiment.

2) Add 0.1 grams of the solid to be purified in a test tube. Add 3 ml of solvent. Stir with

wood sticks and record if S or I. If S, then repeat step 1 using the next solvent. If I, then

proceed to step 3.

3) Heat the test tube with a beaker of very hot water, stir, realizing that if you heat the

test tube too long, some low boiling point solvents will evaporate. Record: S if all solid

dissolves or I if some solid does not dissolve.

4) Repeat steps 1 and 2 for every solvent that the instructor has (usually petroleum ether,

acetone, ethyl acetate, ethanol, and water are the solvents tested) directed you to test.

5) All results should be recorded in your notebook and then on the solubility data sheet.

PRECAUTION: All of the solvents used in Part 1, except water, are flammable. Do not start Part 2 until you are directed to do so by the instructor.

PART 2: RECRYSTALLIZATION OF AN IMPURE SOLID (see Figure 1, page 94)

1) Place 1.0 gram of impure solid into a 250 mL beaker. Add 20 mL of the

recrystallization solvent and 2 boiling chips to the beaker. Do not take the pure solid that

was used for the solubility tests.

2) Set-up steps one and two of the apparatus as shown in Figure 1, page 94.

3) Heat the contents of the beaker to boiling with either a flask heater or Bunsen burner

as advised by your instructor; observe the sample! If your sample hasn't completely

dissolved after the mixture has been boiling for a couple of minutes,

add an additional 10 mL of solvent; reheat to boiling temperature and observe again.

18

It may be necessary to add more solvent to dissolve the crystals ( add in 10 mL

increments). As the beaker is being heated, heat the powder funnel and filter paper with

gentle steam.

4) As soon as the crystals have been dissolved in the hot solvent, add a small amount of

charcoal using a micro spatula, continue to heat for 1 minute, then shut off the heating

source.

5) Without letting the contents of the beaker cool down, pour the mixture in the beaker

through the preheated powder funnel that contains the filter paper. Use the "Hot Hand"

to grab the hot beaker. If crystals are formed during filtration, reheat to a boil then allow

the solution to cool by itself very slowly. After the beaker that contains the filtrate has

cooled to close to room temperature and crystals have formed, cool this beaker an

ice/water bath until it is as cold as the ice water.

7) Filter the purified solid through your Buchner funnel. This is done by wetting the

filter paper in the Buchner funnel with the solvent used to crystallize. Turn the vacuum

(yellow handle) on. When you are sure that the filter paper is matted down, pour the

solid mixture in your beaker, into the Buchner funnel. The solvent should drain into the

filter flask and the solid should be caught on the filter paper in the funnel. You should

see no solid in the filter flask. If you can't get all of crystals out of the beaker, pour some

or all of the filtrate (the solvent that drained into the filter flask) back into the beaker, stir,

and filter again.

8) Store your purified solid in a clean, dry 50 mL beaker in your locker until the

following lab period.

9) Please note this procedure should be applied whenever you recrystallize a solid.

10) Next lab period, you will take a melting point of your dried solid to check its purity.

Identify your unknown based on melting point. You will also measure the weight of the

purified solid and hand it in using a sample vial or envelope. Put a label on the vial with

the following information:

Your Name

Product Name

M.P. Range = _______C

% Recovered =_________

The % Recovered is calculated as follows:

% Recovered = (final weight/starting weight) X 100

19



SOLUBILITY DATA SHEET

CHART OF SOLUBILITIES TO DETERMINE THE BEST

RECRYSTALLIZATION SOLVENT FOR ____________________

KEY: S = very soluble (all solid dissolves in 3 mL of solvent)

I = insoluble (not all solid is soluble in 3 mL of solvent)

Solvent Boiling Point Cold Hot Good Recrystal. Solvent (yes/no)

Petroleum

Ether

Acetone

Ethyl Acetate

Ethanol

Water

Which of the solvents listed above is the best recrystallization solvent for the solid

you tested? Why?

Weight of Crude Solid ______________g

Weight of Recrystallized Solid ____________g

Melting Point Range _________________C

Percent Recovered ______________%

Name of unknown__________________



20

DISTILLATION

INTRODUCTION

Distillation is a process used to purify a liquid. The purpose of todays experiment is for the student to become familiar with how to set-up the apparatus used in a distillation and

to compare two different types of distillations. These two different types are called

simple distillation and distillation with an unpacked column.

The reason why distillation works can easily be expressed by looking at Raoult's Law,

which states that the vapor above a boiling solution will always contain more of the lower

boiling point component than the solution that is boiling. In today's experiment we will

start with a 50/50 solution of acetone (B.P.= 56C) and water (B.P.= 100C). As the

solution is heated and starts to boil, the vapor above the boiling solution will contain

more acetone, the lower boiling point liquid. As this acetone rich vapor moves away

from the heat source and cools, this new solution still contains more acetone and less

water. Eventually, this acetone rich solution will be vaporized again. This vapor will

contain even more acetone and less water. Depending upon the amount of surface area

between the boiling liquid and the water cooled condenser, many of these vaporizations /

condensations can take place. Therefore, the more surface area, the greater the separation

of the two liquids.

In today's experiment, the student will distill a solution of acetone (some students will

be familiar with acetone as it is the solvent used to remove nail polish) and water, trying

to separate, as best as possible, the two liquids. This will be accomplished by collecting

three fractions and measuring their volumes. Fraction I will be collected from a

temperature range of 56 to 62, therefore, this fraction contains only acetone. Fraction II

will be collected between 63 to 90. This second fraction contains a mixture of acetone

and water. The last fraction, fraction III, is the residue. This fraction contains only water.

Ideally, to achieve the best separation, one should get all the acetone in fraction I, no

fraction II, and all the water in fraction III.

WHEN DISTILLING, ALWAYS:

1) Add two boiling chips to the distilling flask. Never add a boiling chip to a hot liquid.

2) Use a thin film of grease whenever glass touches glass. All glass joints must fit tightly

together, use rubber bands.

3) Insert thermometer probe into the adapter. The tip of the probe should be just below

the junction in the three way connecting tube.

4) Cooling water for the condenser enters at the lower position and exits at the top, turn it

on slowly.

5) A good rate of distillation is 1 drop/second.

6) The distillation receiver is always a round bottom flask.

7) Never leave your distillation unattended.

21

PRECAUTION Acetone is flammable, it should not be left in an open container on the bench top. The

joints of the distillation set-up must be tightly fitted together.

PROCEDURE

1) Add 15 mL acetone, 15 mL of water, and 2 boiling chips to a 100 mL round bottom

flask (RBF).

2) Set-up the apparatus as shown for a simple distillation (Figure 3, page 96). Make sure

all glass joints are tight.

3) Turn on the water very slowly, until you see a slow, but steady stream of water

coming out of the condenser.

4) Get your apparatus checked by your instructor.

5) Heat the solution with a flask heater and heat controller so that the rate of distillation

is one drop per second.

6) At a temperature of just above 62C, turn off the heat controller and change the

receiving flask from a 50 mL to a 25 mL RBF. Make sure you did not loosen any glass

joints and then start to heat again.

7) At 90C, turn off the heat controller. Let the residue in the 100 mL RBF cool.

8) Measure and record the three volumes that were collected. Dispose of the fractions as

directed.

9) Repeat this procedure, but set-up an unpacked column distillation apparatus in step 2

(Figure 4, page 97). It is not necessary to clean or dry any equipment.

10) Obtain an unknown acetone/water solution from your instructor and measure the

volume (do not add any additional water). Determine the amount of acetone present in

your unknown solution by using distillation through an unpacked column, as in step 9.

11) Record your results in your notebook and then on the data sheet.

22



DISTILLATION DATA SHEET

SIMPLE DISTILLATION (NO COLUMN)

VOLUMES COLLECTED

T = 56 to 62C _________mL

T = 62 to 90C _________mL

T = 90 to 100C ________mL

UNPACKED COLUMN VOLUMES COLLECTED

T = 56 to 62C _________mL

T = 62 to 90C _________mL

T = 90 to 100C ________mL

UNKNOWN SOLUTION DISTILLATION Starting Volume __________mL

Volume Collected between 56 to 62C___________mL

Percent acetone in unknown solution ______________%

Which method of distillation (no column or unpacked column) was the best? Why?

GRADES

Pre-Lab (20):_____ Experimental Technique (30):_____


23

RESOLUTION OF RACEMIC PHENYLSUCCINIC ACID

INTRODUCTION Because enantiomers have mostly identical chemical and physical properties, their

separation (called a resolution) requires special techniques. Resolution via

diastereeomeric salt formation, first accomplished in 1853 by the father of

stereochemistry, Louis Pasteur, will be the method of resolution demonstrated in this

experiment. Racemic phenylsuccinic acid (RS-PSA) will be resolved using the optically

pure base, S-(-)-Proline (S-Pro)* or R(+)-Proline (R-Pro).. The optical purity of some

samples can be determined using a technique called polarimetry. We will not be telling

you whether you are using S-Pro or R-Pro ! - you will use polarimetry of the PSA sample

that you isolate to discover the stereochemistry of the Proline that you used.

When an acid is mixed with a base, a salt results and this is the case when RS-PSA is

mixed with S-Pro, using isopropanol as a solvent. Two different salts form. The first salt

consists of (S-PSA)-(S-Pro)2, that is, for every one molecule of S-PSA, there are two

molecules of S-Proline associated with it. The second salt is composed of (R-PSA)-(S-

Pro). These two salts can now be separated because of their solubility difference in

isopropanol. The (S-PSA)-(S-Pro)2 salt, being less soluble in the isopropanol,

precipitates out of solution and can be isolated by filtration. The more soluble (R-PSA)-

(S-Pro) salt remains dissolved in the filtrate. The S-PSA can be liberated from its proline

salt form by the addition of hydrochloric acid. The converse happens with RS-PSA and

R-Pro (see diagram above!).

The resolution of enantiomers is a very important topic, especially when dealing with

chiral drugs. For example, with Ibuprofen (Motrin, Advil), the S-enantiomer has all of

the anti-inflammatory activity, while the R-enantiomer has no effect. With

Chlorpheniramine (Chlortrimeton), the S-enantiomer contains all of the antihistamine

activity, while the R-enantiomer has a sedative side effect.

*Stephani, R. and Cesare, V. J. Chem. Educ., 1997, 74, 1226.

** S-(-)-Proline is also called L-(-)-Proline , R-(+)-Proline is also called D-(+)-Proline

24

PROCEDURE (Review the reflux technique (p. 7) and set-up (Figure 2, p. 95), (All equipment should be dry through step 5)

1) Weigh out 1.94g of racemic phenylsuccinic acid in a 150 mL beaker and dissolve it in

50 mL of 2-propanol. Transfer this solution to a clean and dry 100 mL RBF using your

long stem funnel.

2) Add 1.15g of unknown proline (break up any clumps) to the 100 mL round bottom

flask (RBF) using your powder funnel. Use 10 mL of 2-propanol to rinse the small

amount of proline that remains in the beaker. Swirl the flask for several minutes. All of

the proline will not dissolve. Obtain a stir bar from the instructor.

3) Reflux (Figure 2, p. 95) and stir with magnetic stir bar (and stir plate) and with a flask

heater and heat controller for 20 minutes.

4) Air cool the flask to room temperature. This takes about 10 to 15 minutes.

Occasionally swirl the mixture during this time. A lot of solid should be seen when the

flask reaches room temperature. Remove the magnetic stir bar with a magnetic stir

and return the stir bar to the instructor.

5) Stir the mixture in the flask for one minute and then vacuum filter the mixture through

clean, dry equipment. The filter paper should be matted down with 2-propanol. Use the

filtrate to remove all of solid from the flask. Discard the filtrate as directed by the

instructor. Wash the solid with 2 x 15 mL of acetone. Leave the vacuum on for 2 minutes

after the second acetone wash and then press down the solid with a hollow stopper to

remove as much liquid as possible. Dry the solid between two pieces of filter paper.

Discard the acetone filtrate as directed by your instructor.

6) Add 10 mL of 6M HCl to a 100 mL beaker and clamp it in an ice/water bath. When

this solution is cold, add all of the solid from step 5. Stir for about 5 minutes.

7) Vacuum filter the mixture (clean the filtration apparatus with water and mat down the

filter paper with water, the equipment does not have to be dry). Wash the solid in the

Buchner funnel with 2 x 15 mL of water. Let the solid dry in a large beaker until the next

lab period. Discard the filtrate as directed by your instructor.

8) After recording the weight, use a polarimeter to measure the optical rotation, a, of your

phenylsuccinic acid. Do this by adding all of your PSA to a 10 mL graduated cylinder,

add 7 to 8 mL of acetone and stir to dissolve all of the solid. Then add more acetone until

the solution is exactly to the 10 mL mark of the cylinder, stir again. Add this solution to

the polorimeter cell until it is full. Place the cell into the polarimeter record the observed

Be sure to determine whether the optical rotation is plus + or minus-.

Calculate the specific rotation [] and the percent optical purity (% OP) using the formulas shown on the data sheet. Determine if you have resolved R-Phenyl succinic

acid or S-Phenyl succinic acid.

25

NAME________________________________ LOCKER #______________

DATE________________ LAB DAY AND TIME_________________

RESOLUTION OF PHENYLSUCCINIC ACID

DATA SHEET

OVERALL RESOLUTION EQUATION:

DATA FOR PHENYLSUCCINIC ACID

[]max = + _173.3_ (c = 1, acetone) (from CRC Handbook of Chemistry and Physics)

Theoretical Yield = ________g

RESULTS

Weight of (+)-PSA Recovered =_________g

Percent Yield = __________

Observed Rotation = ___________ Record if it is plus + or minus-.

[] = ____________ (c = _________, acetone)

% Optical Purity = _________

My resolved Phenylsuccinic acid is R or S.CIRCLE THE CORRECT ISOMER.

[] = / (lc) where l = length of the cell in decimeters (10 cm = 1 dm) c = concentration in g/mL

% OP = ([]/[ ]max) x 100 where []max = [] of optically pure PSA in acetone



26

SYNTHESIS OF TERTIARY BUTYL CHLORIDE

INTRODUCTION

In this experiment, the student will see that tertiary alcohols react almost

instantaneously with hydrohalic acids at room temperature to form an upper layer of an

alkyl halide. The student will also become familiar with some of the uses of the

separatory funnel and also how to dry organic liquids using drying agents. Before

coming to lab, read the uses of the separatory funnel (page 8) and drying organic liquids

(page 8).

PRECAUTIONS

1) Concentrated hydrochloric acid can cause severe burns.

2) Tertiary butyl chloride is very flammable, therefore, no flames are to be used today.

3) Always vent the separatory funnel when mixing compounds and remove the hollow

stopper when dispensing liquids from it.

PROCEDURE

1) To your separatory funnel add 7.86 g (10 mL) of tert-butyl alcohol and 25 mL of

concentrated hydrochloric acid. (Concentrated hydrochloric acid has a molarity of

12.4M. Knowing this value and that M = mol/L, the number of moles can easily be

calculated. Knowing that the MW of HCl is 36.46g/mol., the number of grams of HCl

also be calculated.

* J.F. Norris, et al, Org. Syn., 1928, 8, 50.

C

CH3

CH3

CH3

Cl+ HCl

tert-Butyl Alcohol tert-Butyl ChlorideHydrochloric Acid

+ H2OCCH3

CH3

CH3

OH

27

2) Gently swirl the contents of the separatory funnel for one minute, then stopper it with

your hollow stopper. Invert and vent the separatory funnel by opening the stopcock to

release the pressure. Make sure you hold the hollow stopper in place when you invert the

funnel. Repeat the shaking, inverting, and releasing of pressure, slowly at first. As the

pressure decreases, gradually increase the shaking. This is done for approximately five

minutes.

3) Clamp the stoppered funnel to a ring stand and let it stand until both layers are clear.

This will take at least 20 minutes. During this time, the student should set up the

distillation apparatus used later in this experiment.

4) When both layers are clear, drain off and discard the lower layer.

5) Add 10 mL of saturated sodium bicarbonate solution to the top layer in the separatory

funnel. Gently swirl the unstoppered funnel for two minutes, and then stopper it, invert,

and release the pressure. This is again repeated, gradually increasing the shaking. Be

sure to frequently vent the funnel.

6) After letting the layers separate for one minute, drain off the lower bicarbonate layer

and discard it.

7) Add 10 mL of water to the top layer, stopper, invert, and vent several times as done

previously.

8) Let the layers separate for one minute and then drain off and discard the lower water

layer.

9) Transfer the top tert-butyl chloride layer to an Erlenmeyer flask and dry it with

sodium sulfate (see page 8).

10) Using your long stem funnel with a very small piece of glass wool, decant the t-butyl

chloride from the sodium sulfate into your 50 mL round bottom flask (RBF).

11) Distill tert-butyl chloride using a simple distillation set-up (Figure 3, page 96) with a

flask heater and heat controller. Collect the product up to and including 52C or until the

distillation stops. Use a 25 mL RBF cooled with ice water as the receiving flask.

12) Pure tert-butyl chloride is a clear, colorless, liquid. If your product is cloudy, dry it

with sodium sulfate before handing it in.

28

ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT

NAME_____________________________________ LOCKER #__________

DATE________________ LAB DAY AND TIME_____________________

TITLE OF EXPERIMENT____________________________________________

BALANCED EQUATION:

NAME OF PRODUCT____________________________________

Molar Mass ___________ M.P(solid)e or B.P.(liquid)

e__________

a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.

b. Moles = Grams/Molar Mass.

c. Coefficients from the balanced equation.

d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.

e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.

GRADING: Pre-Lab (20):_____ Experimental Technique (30):_____


Name of

Reactant

Grams MM Moles

Product Coeff .

Reactant

Coeff.

Moles

of Produc

t

a b

c d

RESULTS:

Actual Yield _________g Percent Yield _________% Melting Point______oC

29

SYNTHESIS OF 2-METHYL-2-BUTENE

INTRODUCTION

In this experiment, 2-methyl-2-butene, an alkene, will be synthesized, by the sulfuric

acid catalyzed dehydration of 2-methyl-2-butanol. This reaction demonstrates that the

more highly branched alkene will be the major product because the hydrogen nucleus on

the number 3 carbon is the easiest to remove. Can you name the minor product in this

reaction?

PRECAUTIONS

1) 2-methyl-2-butene and 2-methyl-2-butanol are flammable, therefore, no flames are to

be used today.

2) Be careful when using the sulfuric acid solution and the sodium hydroxide solution,

both will burn the skin.

3) The product, 2-methyl-2-butene, boils at a low temperature, therefore, it evaporates

very quickly. Do not leave it open to the air. You will notice that the receiving flasks

during the distillations are packed in ice/water. This is to keep the product from

evaporating.

* Whitmore, F.C., Rowland, C.S., Wrenn, S.N., Kilman, G.W., J. Am. Chem. Soc., 1942,

64, 2970.

CH3 CH2 C

CH3

CH3

OH

H2SO4

H2OCH3 CH C

CH3

CH3 + H2O

2-Methyl-2-Butanol (t-Amyl Alcohol)

2-Methyl-2-Butene

30

PROCEDURE

1) Set up a simple distillation (Figure 3, page 96) with the following changes: use a 50

mL RBF that is packed in ice/water as a receiving flask and a 100 mL RBF as the

distilling flask. Use the large condenser and the hollow stopper in the set up. None of

this equipment has to be dry.

2) Add 20.0 mL of the sulfuric acid solution (34 %) to a 125 mL Erlenmeyer flask and

cool it in a beaker of ice water.

3) Slowly, with swirling and continued cooling of the flask, add 10.0 mL of 2-methyl-2-

butanol (tertiary amyl alcohol) to the 125 mL Erlenmeyer flask.

4) Using a long stem funnel, transfer the contents of the Erlenmeyer flask to the 100 mL

RBF of the distillation set-up.

5) Using a flask heater, distill until distillate is no longer obtained. This usually takes

between 10 to 20 minutes if the rate of distillation is one to two drops per second. There

will be liquid left in the 100 mL RBF. Remember that a good rate of distillation is 1 drop

per second!

6) Transfer the contents of the 50 mL RBF to a separatory funnel and add 5 mL of 10 %

NaOH solution. Swirl the unstopped funnel for one minute and then stopper it with your

hollow stopper and shake the funnel with frequent venting. Clamp the separatory funnel

to a ring stand and let the two layers separate. Drain off and discard the lower aqueous

layer as directed by your instructor.

7) Pour the top layer (2-methyl-2-butene) into a clean, dry 50 mL Erlenmeyer flask.

Cork and cool the flask in and ice/water bath and dry the product with sodium sulfate.

8) Decant the liquid through a clean, dry, long stem funnel that contains a small amount

of glass wool into a 50 mL RBF and distill using simple distillation (Figure 3, page 96)

with a flask heater and controller. All equipment must be clean and dry. Use the west

(thin) condenser and a 25 mL RBF that is packed in ice/water as a receiving flask.

Collect up to 43C as pure product.

9) Hand in the product today, as directed by your instructor.

31


NAME_____________________________________ LOCKER #__________



BALANCED EQUATION:

NAME OF PRODUCT____________________________________


e__________

CALCULATION OF THEORETICAL YIELD

Lowest moles of product ________ X MM of Product ___________=

RESULTS

ACTUAL YIELD ___________G PERCENT YIELD ___________%






GRADING: Pre-Lab (20):______ Experimental Technique (30):_____

Yield & Purity (30):______ Post Lab Questions (10):_____ Lab Report Grade = ______

Name of

Reactant

Grams MM Moles

Product Coeff .

Reactant

Coeff.

Moles

of Produc

t

a b

c d

32

SYNTHESIS OF 2,4,4-TRIMETHYL-2-PENTENE AND ISOMER

INTRODUCTION

When tert-butyl alcohol is heated in the presence of sulfuric acid, 2-methyl propene

(isobutylene) is produced. The mechanism for this reaction is similar to the synthesis of

2-methyl-2-butene, the last experiment.

Isobutylene has a boiling point of -7C, therefore, it is a gas at room temperature.

This isobutylene gas, if left in the presence of the sulfuric acid solution, will react further

and dimerize to give the following two isomers: 2,4,4-trimethyl-2-pentene and 2,4,4-tri-

methyl-1-pentene. If hydrogen gas and a catalyst, such as nickel, were allowed to react

with these two pentenes, 2,2,4-trimethylpentane would form. 2,2,4-trimethylpentane has

the common name iso-octane or synthetic gasoline. It has been assigned an octane

number of 100. Compare this rating, to the octane number of the gasoline that you use in

your car. Most unleaded gasoline has an octane rating between 87 and 92.

When calculating the TY for this experiment, since both pentene products are

collected together, add the theoretical yield of both pentene products to get the correct

overall TY. This is done because both of the pentenes boil within 5C of each other and

would be difficult to separate using simple or column distillation.

* Whitmore, F.C., Ind. Eng. Chem., 1934, 26(1), 94-95.

Overall equation:

4 CCH3

CH3

CH3

OHH2SO4

H2OCH3 C

CH3

CH2 + H2O4 4Isobutylene

4 CH3 C

CH3

CH2H2O

H2SO4CH3 C

CH3

CH3

CH2 C

CH3

CH2 + CCH3

CH3

CH3

CH C

CH3

CH3

CCH3

CH3

CH3

OHH2SO4

H2OCCH3

CH3

CH3

CH C

CH3

CH3+CH3 CCH3

CH3

CH2 C

CH3

CH2

tert-Butyl Alcohol 2,4,4-Trimethyl-1-Pentene 2,4,4-Trimethyl-2-Pentene

+ 4 H2O4

33

PRECAUTIONS

1) Be careful with the sulfuric acid solution, it burns.

2) Both tert-butyl alcohol and the two pentene products are flammable. Use a flask

heater for the reflux and the distillation, do not leave them unattended. Make sure glass

joints are fitted tightly together.

PROCEDURE

1) Clamp a 100 mL RBF to a ring stand and add 28 mL of 50 % aqueous sulfuric acid

solution to it.

2) Slowly add 10.0 mL of tert-butyl alcohol and immediately attach a reflux condenser.

3) Using the flask heaters and controller, gently reflux (Figure 2, page 95) the solution

for 30 minutes. A good rate of reflux for this reaction is a gentle boil. During this time,

you can see the formation of an upper layer, which is the pentene products.

4) Cool the reaction mixture to room temperature by lowering the 100 mL RBF into an

ice/water bath. Leave the condenser on and the water running until the reaction mixture

is cool.

5) Add the reaction mixture to a separatory funnel and drain off and discard the lower

layer as directed by your instructor.

6) Add 20 mL of water to the top layer in the separatory funnel. Shake the funnel with

venting.

7) Drain off and discard the lower aqueous layer as directed by your instructor.

8) Add the top layer to an Erlenmeyer flask and dry it with a small spatula full of sodium

sulfate.

9) Decant the dried liquid through a long stem funnel that contains a small amount of

glass wool into a clean, dry 50 mL RBF.

10) Set-up a simple distillation (Figure 3, page 96) with a flask heater and controller, use

a 25 mL RBF as a receiving flask. The position of the temperature probe is important.

All equipment must be clean and dry. If you have some unreacted tert-butyl alcohol, it

will distill over at approximately 82C. Change the receiving flask at 90C if any alcohol

did distill over. Collect between 100 - 108C as pure product. The alkenes should be

clear and colorless, hand it in as directed by your instructor.

34


NAME_____________________________________ LOCKER #__________



BALANCED EQUATION:

NAME OF PRODUCT____________________________________


e__________



RESULTS









Name of

Reactant

Grams MM Moles

Product Coeff .

Reactant

Coeff.

Moles

of Produc

t

a b

c d

35

OXIDATION OF CYCLOHEXENE TO ADIPIC ACID

INTRODUCTION

Double bonds can be cleaved by several oxidizing agents. The oxidizing agent to be

used in this experiment is potassium permanganate. The mechanism of this oxidation

involves the initial formation of a cis-glycol. The carbon-carbon bond of the glycol is

then further oxidized by the permanganate and is cleaved to yield the dicarboxylic acid,

adipic acid. Adipic acid is used in the manufacturing of nylon.

PRECAUTIONS

1) Be careful with the potassium permanganate, it stains clothes and skin.

2) Be careful with the concentrated hydrochloric acid, is severely burns.

PROCEDURE

1) In a 100 mL RBF, dissolve 4.13 g of potassium permanganate in 75 mL of hot tap

water (stir for 4 or 5 minutes with a magnetic stirrer).

2) Make a solution of 1.0 mL of cyclohexene in 5 mL of acetone. In approximately one

milliliter increments, add this solution into the 100 mL RBF (use a transfer pipet for the

addition). Gently stir the flask with the magnetic stirrer throughout the addition.

3) After the addition is complete, attach your large condenser to the RBF. With water

running up through the condenser, heat the flask very gently with flask heater for 20

minutes, continue the stirring. During this time, in a 400 mL beaker, dissolve 3 g of

sodium bisulfite in about 200 mL of hot water. Save this solution to clean all of your

equipment that will have a brown manganese dioxide stain throughout this experiment.

4) Allow the reaction mixture to air cool for 5 minutes.

* Golendeev, V.P., Trudy Gor'kovsk. Politekh. Inst., 1955, 11, 5-11.

4

PotassiumPermanganate

Cyclohexene

Adipic Acid

3 HOOC CH2 CH2 CH2 CH2 COOH

HCl

2 KOH+3 8 2H2O+MnO2+-- C

O

O K+

)CH2(K+ O C

O

KMnO4+ 83

36

5) Remove the condenser and add 2.0 g of sodium bisulfite in small increments over 10

minutes to the hot reaction mixture (use your powder funnel). Swirl and stir the mixture

for 4 or 5 minutes, then cool it in an ice bath to below room temperature.

6) While the flask is cooling, add 5 or 6 large spoonula's full of celite (see page 8, filter

aid) to 40 mL of water in a 100 mL beaker.

7) Using water, mat down a small piece of filter paper on the Buchner funnel of your

filtration equipment. With the vacuum on swirl and pour the celite/water mixture from

step six into the Buchner funnel. The 40 mL of water will filter through into the filter

flask and the celite should form a layer that completely covers the filter paper. Slowly

release the vacuum and discard the 40 mL of water from the filter flask.

8) Filter the cooled reaction mixture through the Buchner funnel that contains the celite.

Never fill the Buchner funnel much more than half way. The filtrate must be colorless.

9) Add 20 mL of water to the 100 mL RBF to rinse it. Pour this 20 mL of water onto the

brown solid (MnO2) in the Buchner funnel. Transfer the filtrate (the liquid in the filter

flask) to a 150 mL beaker (the beaker should be pre-marked for 15 mL) and give it to

your instructor until next lab period. Leave it uncovered.

NEXT LAB PERIOD (review recrystallization, pages 7 and 93)

10) Concentrate the filtrate to until 15 mL of liquid remains in the 150 mL beaker. Use

the Bunsen burner as a heat source.

11) As soon as you can, transfer the hot 15 mL of solution remaining in your 150 mL

beaker into a clean 100 mL beaker. Cool this solution in an ice/water bath until it is

below room temperature.

12) Acidify the 15 mL of solution in the 100 mL beaker until the pH = 1-2 by dropwise

adding concentrated hydrochloric acid. Stir the mixture after adding each drop of acid

and check the acidity using EMD pH strips. White crystals of adipic acid will precipitate

from the water. Cool this solution in an ice/water bath with occasional stirring until it is

below room temperature.

13) Vacuum filter the mixture and then combine your adipic acid with your lab hood

partner and recrystallize the adipic acid using about 5 to 10 mL of water as the

recrystallization solvent, did you look at pages 7 and 93?

14) Let the pure adipic acid dry in your locker in an open beaker until next period. Clean

and dry all glassware for next period.

37


NAME_____________________________________ LOCKER #__________



BALANCED EQUATION:

NAME OF PRODUCT____________________________________


e__________



RESULTS









Name of

Reactant

Grams MM Moles

Product Coeff .

Reactant

Coeff.

Moles

of Produc

t

a b

c d

38

SYNTHESIS OF 2-METHYL-4-HEPTANONE

INTRODUCTION

Many times starting materials are not readily available to synthesize the desired

product in one step. It is first necessary to synthesize, in one or more steps, compounds

that can then be converted into the final product. This experiment is an example of a

multi-step synthesis to obtain the desired product, 2-methyl-4-heptanone. Infrared

spectroscopy (IR) will be used to determine if the reactions were successful.

One of the most versatile synthetic reagents in organic chemistry is the alkyl or

aryl magnesium halide: the Grignard reagents. Grignard reagents were discovered by P.

A. Barbier and their chemistry was worked out extensively by his student, Victor

Grignard (Noble Prize, 1912).

In today's experiment, you will use one of two different "routes" to make the same

compound. Which Grignard and alkyl halide you use will depend on the Route you are

assigned! The First reaction involving the Grignard reagent is split into two steps:

In the first step, the Grignard reagent is prepared by reacting an alkyl halide, with

magnesium under anhydrous (no water) conditions (first equation). In the second step,

the Grignard reagent is allowed to react with an aldehyde to obtain the salt of 2-methyl-4-

heptanol. The salt is easily hydrolyzed by the addition water (second equation).

Finally, this alcohol will be converted to the corresponding ketone, 2-methyl-4-

heptanone, using sodium hypochlorite as the oxidizing agent (third equation).

* J. Chem. Educ., 1991, 68, 71.

39

PRECAUTIONS

1. Diethyl ether is extremely flammable; NO BUNSEN BURNERS are to be used

today.

2. All reactions are exothermic, add reagents cautiously and as directed.

3. Sodium hypochlorite is a bleaching agent, wear your lab coat.

4. When mixing in the separatory funnel, swirl gently with the stopper off. When

shaking, vent the separatory funnel frequently.

PROCEDURE

DO NOT CLEAN OR RINSE OUT ANY GLASSWARE UNTIL AFTER STEP #10

1) All apparatus must be cleaned and dried the lab period before starting this experiment.

2) Carefully insert the prepared calcium chloride tube into your thermometer adapter.

3) Set-up the apparatus as follows: clamp a 100-mL RBF to a ring stand and attach a

claisen connecting tube. To the side opening of the tube attach the large condenser. Place

the calcium chloride tube on top. To the opening of the claisen tube that is directly over

the flask, place a separatory funnel, which will function as an addition funnel. This set-

up remains the same until step #11.

4) Weigh out magnesium turnings (1.9 g) and grind them with a mortar and pestle for

approximately one minute, then transfer then to the 100 mL RBF. Add and a few crystals

of iodine. Carefully, place a magnetic stir bar into your 100 mL RBF.

5)Route A: Make a solution of 1-chloropropane (4.07 g, 4.54 mL) in 15 mL of diethyl

ether in the separatory funnel

Route B:Make a solution of 1-chloro-2-methylpropane (4.81 g, 5.45 mL) in 15 mL of

diethyl ether in the separatory funnel. Swirl the apparatus to make sure the halide/ether

solution is well mixed.

(Review precautions). Turn on the water to the condenser.

6) Begin adding, DROPWISE, a small amount of the 1-chloro-2-methylpropane/ether

solution to the flask (approx 40 drops). The contents of the flask should become cloudy,

small bubbles should appear, the ether should begin to boil and reflux and the iodine

brown color should disappear. Be patient, if after 5 minutes there is no sign of a reaction,

notify your instructor. Then begin stirring with magnetic stir bar. Make sure the flask is

centered relative to the stir plate.

7) Keeping the reaction under control, add the rest of the 1-chloroalkane/ether solution, a

portion at a time, to maintain a steady rate of reflux. (Approx. 1-2 drops/sec) After all

has been added, close the separatory funnel and heat the flask by using a beaker of hot

water so that the reaction mixture gently continues to reflux for 20 minutes.

40

8) Cool the reaction mixture in an ice/water bath to room temperature.

9) Route A: Make a solution of 3-methylbutanal (2.84g, 3.61 mL) in 15 mL of ether in

the separatory funnel

Route B: Make a solution of butanal (2.40g, 2.92 mL) in 15 mL of ether in the separatory

funnel

and then dropwise, add this solution to the 100 mL RBF with stirring. After the addition

is complete, reflux the reaction mixture with a beaker of hot water for 15 minutes. Cool

the reaction mixture to below room temperature before proceeding to the next step.

10) Carefully, with constant stirring, add 10 mL of water, in small portions, from the

separatory funnel to the reaction mixture. Stir for several minutes. IF you have time

AND the solution above the solids is clear, complete steps 11-14. If not, stopper the

flasks loosely, and continue at the next lab. Return the magnetic stir bar to the instructor.

PART 2

11) Decant the solution from the unreacted magnesium into a separatory funnel, it maybe

necessary to add 20-40 mL of additional ether to the reaction flask, add 10mL of water to

the separatory funnel, shake and vent, allow layer separation and discard the lower

aqueous layer in the waste container (NOT THE SINK).

12) Add 30 mL of 5 % sodium hydroxide (NaOH) solution, shake and vent, allow layer

separation, discard the aqueous bottom layer as above and transfer the top ether layer to a

100 mL RBF.

13) Distill the ether from a 100-mL RBF using hot water bath. (simple distillation; see

diagram on page 95 lab text, you can substitute a glass stopper for the thermometer) Your

product is the residue of the distillation; the ether, which distills over, is collected in the

"recovered ether" bottle. Cool the receiver with ice water.

14) Add 10 mL of acetic acid to the 100-mL flask that contains the 2-methyl-4-heptanol.

Clamp this flask in a small beaker of ice water for 2-3 minutes. With the flask still in the

ice water, carefully add 30-mL aqueous 2.1M sodium hypochlorite solution, in small

portions, gently stirring (with a magnetic stir bar) the mixture after each addition.

15) Remove the flask from the ice water and swirl the solution carefully while it returns

to room temperature. Return the magnetic stir bar to your instructor.

41

EXTRACTION TECHNIQUES USING DICHLOROMETHANE

Dichloromethane is denser than water and most organic compounds and will therefore

appear in the lower layer of the extraction. When you extract an aqueous layer 2 times,

you remove the lower layer after the first extraction, SAVE IT, and re-extract the

remaining upper aqueous layer with a fresh amount of dichloromethane. You will then

combine the two lower layers, which contain dichloromethane and whatever was

extracted into it. The upper layer is then disposed of properly.

16) Add 30 mL of water to the reaction in step #16 and transfer it to a separatory funnel.

Extract the aqueous solution 2 times with 30 mL of dichloromethane. Add 5 mL of water

to the combined dichloromethane extracts, shake and separate the lower organic layer.

17) Dry the dichloromethane layer with sodium sulfate, decant and distill off the

dichloromethane using a simple distillation. Cool the receiver with ice water bath. Distill

the light fractions (the low boiling point compounds) up to a thermometer temperature of

60O

C, 20 degrees above the boiling point of dichloromethane. The 2-methyl-4-heptanone

remains as the residue of the distillation. Take an IR of this product. Label the key

peaks in the IR. Hand in the product as directed. Put the dichloromethane in the bottle

labeled "Recovered Dichloromethane".

42


NAME_____________________________________ LOCKER #__________



BALANCED EQUATION:

NAME OF PRODUCT____________________________________


e__________



RESULTS









Name of

Reactant

Grams MM Moles

Product Coeff .

Reactant

Coeff.

Moles

of Produc

t

a b

c d

43

SYNTHESIS OF ETHYL IODIDE

INTRODUCTION

This experiment demonstrates a second method that an alkyl halide can be

synthesized. Compare this method to the method used to synthesize t-butyl chloride. In

this experiment the student is actually performing two reactions. The first reaction is the

synthesis of phosphorus triodide. As soon has the phosphorus triodide is formed, it will

react with the ethyl alcohol to produce the alkyl halide, ethyl iodide. When the product

of a first reaction (phosphorus triodide) is used, without isolation or purification, as a

reactant in the formation of a second product (ethyl iodide), then these two reactions are

said to be done "In situ".

To calculate the theoretical yield of ethyl iodide, use the bottom, overall equation.

PRECAUTIONS

1) Phosphorus, Iodine, and Ethyl Iodide are dangerous. Avoid contact of these three

chemicals with the skin. Avoid breathing these chemicals.

2) Ethyl alcohol and ethyl iodide are flammable. During the reflux and both distillations,

all glass joint must be tightly fitted together.

* King, H.S., Org. Syn., 1933, 13, 60 - 65.

Phosporus triodide

2PI3

6CH3CH2OH + 2PI3

6CH3CH2OH

2P + 3I2

2P + 3I2+

+ H3PO3I6CH3CH2

+ H3PO3I6CH3CH2

Overall equation:

Ethanol Ethyl iodide

44

PROCEDURE 1) Clamp a 250 mL round bottom flask (RBF) to a ring stand and add 1.4g of red phosphorus (0.045 moles) and 10 mL of absolute ethanol (0.17 moles)

using a powder funnel. Don't forget to add two boiling chip to the flask.

2) Slowly, a spatula-full at a time, add 10g (0.04 moles) of iodine through the powder

funnel and into the 250 mL RBF. Swirl the reaction mixture after each addition, gently

rocking the ring stand from side to side for 30 seconds. The RBF should get warm, due to

the exothermic reaction taking place. If the reaction mixture begins to boil, cool the flask

in 600 mL beaker of ice/water until the boiling stops, then re-start the addition of iodine.

3) After all of the iodine has been added, attach a reflux condenser (the "fat" condenser)

and swirl the mixture for several minutes.

4) Reflux (Figure 2, page 95) with a flask heater and controller for 30 minutes.

5) Cool the reaction mixture in ice/water, without removing the condenser, until the

contents of the flask are approximately at room temperature.

6) Distill the contents of the 250 mL flask. Set up a simple distillation (Figure 3, page

96). Use a flask heater and controller. Use a hollow stopper instead of a thermometer

adapter and thermometer. Use the same condenser that was used for the reflux, no need

to clean it. Use a 100 mL RBF as a receiving flask. Distill until there is no liquid left in

the 250 mL RBF. You will see a dark colored solid in the distilling flask and a yellow,

red or orange colored distillate in the 100 mL receiving flask.

7) Transfer the impure ethyl iodide from the 100 mL RBF to a separatory funnel and add

10 mL of 3% sodium hydroxide. Put the hollow stopper on the funnel. Invert and vent

the funnel several times. Shake the funnel more vigorously and continue to vent. Clamp

the funnel to a ring stand and allow the contents of it to separate into two layers.

8) Drain the lower layer (impure ethyl iodide) & save it. Discard the top aqueous layer.

9) Put the bottom layer back into the separatory funnel and add 10 mL of water. Shake

and vent the funnel several times, then let the two layers separate.

10) Drain the lower layer into an Erlenmeyer flask and dry it with sodium sulfate.

Discard the top, water layer.

11) Distill the dried ethyl iodide using a flask heater and a simple distillation (Figure 3,

page 96). Use a 50 mL RBF as a distilling flask and a 25 mL (RBF) as a receiving flask.

Use the west ("thin") condenser, the thermometer adapter, and the 150 degree

thermometer. All of the equipment must be clean and dry. Collect up to 73C as pure

product.

12) Ethyl iodide is a clear colorless liquid. Hand in the product in a 30 mL sample bottle

with the usual label.

45


NAME_____________________________________ LOCKER #__________



BALANCED EQUATION:

NAME OF PRODUCT____________________________________


e__________



RESULTS









Name of

Reactant

Grams MM Moles

Product Coeff .

Reactant

Coeff.

Moles

of Produc

t

a b

c d

46

CHECK OUT

47

ORGANIC POLYMERS THE SYNTHESIS OF NYLON AND THE IR ANALYSIS OF POLYMERS

Objective

The purpose of this experiment is to synthesize the polymer, Nylon-6,10, and to

determine the identity of an unknown polymer using infrared spectroscopy.

Introduction

Polymers are very large molecules composed of repeating subunits called

monomers. Polymers can either be synthesized through addition reactions of alkenes or

via condensation reactions. In addition reactions, the carbon-carbon double bond within

the alkene is broken and a new covalent bond between the two monomers is formed. In

the second type of reaction, two monomers condense together to form the polymer and

water as a by-product. In this experiment, Nylon-6,10 (an amide) will be synthesized by

reacting an amine with an acid chloride.

Nylon-6,10 is a polyamide formed from the reaction of a diamine, an amine that

has an NH2 group at each end, with a diacid chloride, which has a COCl group at each end. Nylon-6,10 is named based on the structure of its amide monomer unit. The

diamine used is hexamethylene diamine, which consists of six carbons while the diacid

used is sebacoyl chloride, a component containing ten carbons. When the diamine and

diacid condense, HCl is formed as a by-product, which can cause undesirable side

reactions. As a result, the diamine is dissolved in a sodium hydroxide solution such that

it neutralizes the HCl as soon as it is formed.

Nylon is a very versatile substance. It is strong enough to be used in tires, but can

also be spun fine enough to be used in hosiery. It is also very durable as it washes and

dries easily, and holds shape well, which is why it is used in fabrics.

48

The identification of various compounds including polymers can be attained using

infrared (IR) spectroscopy. Since the absorption of infrared light can result in the

vibration of bonds, and the absorption of different bonds occurs at different frequencies,

the different functional groups present in the molecule can be identified from its IR

spectrum. IR spectroscopy is especially used in the waste management industry to aid

recyclers in identifying plastics that are missing their identification code. Plastics are

synthetic polymers that can be distinguished from each other based on the IR absorption

frequencies of the functional groups present in their monomeric units. In this experiment,

you will obtain the IR spectrum of an unknown synthetic polymer and confirm its identity

using Table 1.

Table 1: Structure of the Monomer Unit of Recycled Synthetic Polymers

Name of

Plastic

Identification

Code Structure of monomer

Poly(ethylene

terephthalate)

Polyethylene

Poly(vinyl

chloride)

Polypropylene

Polystyrene

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