333 Lab Procedures

7/29/2019 333 Lab Procedures

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2/9/13 8:18 PM333 Lab Procedures

Page 1 of 36http://www.chem.sc.edu/faculty/handy/333labproc.htm

Please note the following:1) In order to be enrolled in CHEM 333L, you must have completed or currently be enrolled inCHEM 333.2) Should you drop CHEM 333 during the course of the semester, you must also drop CHEM333L.

Points Breakdown for CHEM 333L:Quizes: 30Prelab: 30Postlab: 40

Prelab

Section PointsName, Date, Section 1Objectives 2Theory 10

Reagent Table, Precautions 10Procedure, Apparatus, Technique 5Disposal 2

Postlab

Section PointsObservations 10Results, Data 10Conclusion, Spectral Analysis 20

Experiment 1:

Recrystallization

Part A: Purification of Phthalic Acid by recrystallization. (Microscale)Part B: Identification of an unknown organic solid by recrystallization and the mixed meltingpoint technique. (Microscale)

For an example lab write-up, consult the document titled "Sample Lab Report" on the homepage.

Prelab

Objectives:Part A:1. Purify a commercial sample of phthalic acid by recrystallization2. Record the mass and melting point of the recrystallized product3. Determine percent recovery

Part B:1. Establish a suitable solvent or mixed solvent system (pair) by trial and error procedure2. Recrystallize 100 mg of the given unknown, filter, and dry product


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3. Record mass and melting point. Determine percent recovery4. Identify unknown by the mixed melting point method5. Record IR, tabulate and analyze data

Theory:Discuss and summarize the following:1. Properties of solids

......a) Forces that hold organic solids together

......b) Melting point2. Solvent properties......a) Temperature dependence of solubility......b) Ideal solvent3. Types of impurities......a) Soluble......b) Insoluble4. Purification of a solid by recrystallization5. Using melting point data to analyze purity

......a) Melting point depression......b) Possible impurities

Reagent Table:Information that should be included for each compound is as follows: compound name,structure, molecular formula, molecular weight, melting/boiling point, density, physical properties(color, odor, state, etc.)

Precautions:Flammability, toxicity, corrosiveness, etc. (please be specific about the hazards associated withany particular compound) of the reagents in the table, handling of reagents, assembling

apparatus.

Apparatus:Sketch the apparatus used to conduct the experiment and label the component parts.


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Procedure:Part A:1. Place 100 mg of phthalic acid in a small test tube.2. Using a Pasteur pipette, add 1-1.5 mL of water (add enough to just cover the solid).3. Place a boiling stone in the test tube and heat the solution to boiling on a sand bath. Use atest tube holder when heating your solution. Use a variac setting of 50.4. As soon as boiling begins, add water dropwise until most of the solid has dissolved.CAUTION!!! Do not add too much water! You must maintain a saturated solution. Insolubleimpurities will remain in suspension.5. Remove the insoluble impurities by hot gravity filtration (consult TA before performing this

step).6. Allow the hot solution (the filtrate) in the test tube containing the phthalic acid and solubleimpurities to stand for 5-10 minutes at room temperature.7. Complete the crystallization by cooling the solution in the test tube in an ice bath.8. Collect the product by suction filtration.9. Wash the product free of soluble impurities with ice cold solvent (water).10. Leave product sitting in the Buchner funnel for a few minutes to remove as much of thesolvent as possible.11. Carefully dismantle the suction filtration unit and transfer the pure sample of phthalic acid toa piece of filter paper for drying.12. Spread the solid onto the filter paper to dry. Cover with an inverted beaker and leave for 10-15 minutes.13. Record the mass of the dried product and calculate the percent recovery.


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14. Determine the melting point.

Part B:1. Choosing a recrystallization solvent or solvent pair:......a) Obtain 6 test tubes.......b) Place a few crystals of the impure unknown into each test tube. (possible unknowns arebenzoic acid, acetanilide, and acetylsalicylic acid)

......c) Treat each sample with a different solvent to determine your best solvent. Remember thecharacteristics of a good solvent. (Possible solvents are water, methanol, ethanol, diethyl ether,acetone, and hexane)......d) If you use a solvent pair, dissolve the unknown in the better solvent and then add thepoorer solvent until ............saturation occurs.2. After determining the best solvent, dissolve 100 mg of the unknown in a small test tube.Remember, volume of solvent is critical. Dont forget the boiling chip.3. Recrystallize the unknown, dry it, record the mass, and determine the melting point as in partA.4. Determine the identity of the unknown by the mixed melting point method. Calculate percent

recovery.

Disposal:State how to dispose of the leftover reagents and the product.

Postlab

Observations:Record observed physical changes (precipitation, color, odor, temperature, etc.)

Results/Data:Report actual mass of product obtained, percent recovery, melting/boiling point, color and shapeof crystal, etc. Show allcalculations.

Conclusion:Identify any unknowns. Suggest an explanation for a poor recovery or an impure product. In thissection, possible explanations should be given for any unusual observations made.

Experiment 2:

Simple and Fractional Distillation

Prelab

Objectives:1. Set up a simple distillation apparatus2. Carry out a simple distillation of a 1:1 mixture of cyclohexane and toluene, collecting thedistillate (a mixture)3. Plot a temperature vs. volume curve

4. Record the barometric pressure5. Set up a fractional distillation apparatus


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6. Carry out a fractional distillation7. Plot a temperature vs. volume curve8. Record IR, tabulate and analyze data

Theory:Discuss and summarize the following:1. Properties of liquids:

......a) Vapor pressure

......b) Boiling point2. Factors that cause variations in the boiling points of liquids:......a) Internal factors............1) Molecular weight............2) Polarity............3) Shape......b) External factors............1) Applied pressure (usually atmospheric pressure) on the liquid............2) Added solute

3. Purification of a liquid by distillation:......a) Types of distillation:............1) Simple............2) Fractional............3) Vacuum4. Temperature vs. volume curves (temperature as a function of volume)5. General points to include:......a) Barometric pressure......b) Viscosity......c) Azeotropes

Reagent Table:See experiment 1

Precautions:See experiment 1 and also note the following:1. Cyclohexane and toluene are flammable, so make sure that the apparatus is air tight.2. DO NOT add boiling chips to a hot liquid. A superheated liquid may boil over or even explode.3. DO NOT lubricate your thermometer with grease when pushing it through the thermometeradapter. If you need a lubricant, use glycerin.4. Gloves will be provided when you enter the lab in order to prevent direct contact of the

organic solvents with your skin.

Apparatus:See experiment 1 and refer to pages 94 and 96 for diagram.


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Procedure:Simple Distillation:

Glassware:1. 25 mL Round Bottom Flask2. Sidearm Connector3. Thermometer (and Therm. Adapter)4. Distillation Column5. Take-Off Adapter/Vacuum Adapter6. Two 10 mL Graduated Cylinders

Other Items:1. Two Ring Stands2. 50 mL Heating Mantle3. Two 2-4 foot sections of Rubber Tubing4. One Rubber Band

1. Place 15 mL of a 1:1 mixture of cyclohexane and toluene in a dry, 25 mL round bottom flaskwith a boiling chip.2. Set up a simple distillation apparatus as shown on page 94. (Lightlygrease all ground glassjoints with a silicon lubricant.)3. Follow all precautions - heat strongly until boiling starts. Initially set your variac between 75and 80. (Make sure that your variac is plugged in.)4. Adjust the rate of heating so that distillate is produced at a rate of one drop/second.5. Record temperature at 0.5 mL increments.6. Collect approximately 13 mL of distillate, then stop the distillation.

7. Record the barometric pressure.8. Plot boiling point vs. volume of distillate (temperature as a function of volume).9. Save the distillate for the fractional distillation experiment.


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Fractional Distillation:

Glassware:1. 25 mL Round Bottom Flask2. Vigreux or Fractionating Column3. Short Path Distillation Unit4. Thermometer (and Therm. Adapter)

5. Two or three 10 mL Graduated Cylinders6. Several (10-12) Test Tubes7. Two Sample Vials

Other Items:1. Two Ring Stands2. 50 mL Heating Mantle3. Insulating Pad4. Two 2-4 foot sections of Rubber Tubing

5. One Rubber Band

1. Pour the 13 mL of distillate from the previous experiment into a 25 mL round bottom flask andassemble the apparatus for fractional distillation as shown in figure 5.11 on page 96.2. Heat liquid to its boiling point with your variac set once again at 75-80.3. Insulate the top half of the round bottom flask with an insulating pad (Be careful). Seelaboratory TA for instructions on constructing an insulating pad.4. When you notice a ring of condensate rising up the Vigreux column, turn up the heat

gradually.5. Once the vapor begins condensing, adjust variac so that it will continue dripping steadilywithout any drop in temperature at a rate of not greater than 1 ml/2 minutes or about 1 drop/2seconds.6. Observe the rate of distillation, and keep it steady by increasing the heat as required7. Record the temperature for each increment of 0.5 mL of distillate collected. Make morefrequent readings when the temperature begins to rise abruptly. Keep a series of labeled tubesor flasks to collect the fractions.8. Continue collecting distillate through a second constant temperature zone or until little mixtureremains in round bottom flask.

9. Stop distillation before round bottom flask goes dry.10. Plot a temperature vs. volume curve and record any observations made during the course ofthe fractional distillation.11. Combine the fractions which you think are pure and turn in the two products in labeled vials.Record the boiling point, range, and the volume of each fraction. Save distillate for IR analysis.

Disposal:See experiment 1 and also note the following:Dispose of organic solvents in a container designated by your TA. DO NOT pour organic

solvents down the drain.

Postlab(See experiment 1)

Experiment 3:

A Chemical Extraction

Prelab


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Objectives:1. Separate the components of a ternary mixture by a chemical extraction procedure2. Recrystallize each component and record the melting point of each3. Calculate the total percent recovery of the ternary mixture. The exact mixture composition isnot known. Calculate percent composition of each component out of the ternary mixture4. Record IR, tabulate and analyze data

Theory:Discuss and summarize the following:1. Types of extraction......a) Solid/liquid......b) Liquid/liquid......c) Acid/base2. Solubility......a) Properties of a good solvent......b) Distribution coefficient3. General points

......a) Strategy for acid/base extractions......b) Emulsions

......c) Pressure build up

......d) Need and method for drying organic layer


Precautions:See experiment 1

Disposal:See experiment 1

Apparatus:See experiment 1


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Procedure:1. Obtain three test tubes, weigh, and label them (1,2,3 or A,B,C)2. Obtain .200 grams of mixture.3. Into TT-A, add the ternary mixture and dissolve with 2 mL of ether.4. Into TT-A, add 1 mL of NaHCO3. Shake well (covered) or agitate binary solution by using a

Pasteur pipette. This is done by squeezing the bulb and releasing it to allow the mixture to betaken into and expelled out of the pipette.5. Extract the bottom layer in TT-A and put into TT-B. (Set aside)6. Into TT-A, add 1.0 mL of NaOH. Shake well as before and remove the lower layer. Put intoTT-C. (Set Aside)

TTA: Naphthalene1. Add 20 drops of H2O

2. Shake and remove H20

layer.3. Add MgSO4 (1 micro-

scoop).4. Decant or filter outMgSO4. and obtain mass.

5. Evaporate the ether off.6. Obtain mass of residue.

TT-B: Benzoic Acid1. Add 20 drops of ether.2. Remove ether layer andDiscard.3. Add HCl (dropwise untilcloudy). Be sure to shakeor stir gently after everydrop of acid.4. Cool, filter, dry, and

obtain mass.5. Find melting point andpercent composition.

TT-C: 2-Naphthol1. Add 20 drops of ether.2. Remove ether layer andDiscard.3. Add HCl (dropwise untilcloudy). Be sure to shakeor stir gently after everydrop of acid.4. Cool, filter, dry, and

obtain mass.5. Find melting point andpercent composition.


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7. Find melting point andpercent composition.

6. Calculate total percentrecovery of the ternarymixture.

Postlab

(See experiment 1)

Experiment 4:

Thin Layer Chromatography (TLC)

Prelab

Objectives:1. Synthesize acetylsalicylic acid from salicylic acid. Calculate theoretical yield2. Record mass, melting point, and calculate percent yield3. Record IR, tabulate and analyze data for pure acetylsalicylic acid4. Perform TLC on various standard analgesics5. Calculate Rfvalues

6. Determine the identity of an unknown analgesic by comparing its Rfvalue to those of the

standard analgesics

Theory:

Discuss and summarize the following:1. How TLC works......a) Capillary action......b) Mobile phase, stationary phase......c) Adsorption, desorption2. Rfvalues

......a) Solvent front

......b) Calculation of Rf3. Usefulness of TLC......a) Limit of detection

......b) Determination of number of compounds......c) Identification of substances (co-spots)

......d) Monitoring progress of reactions

......e) Monitoring purification processes

......f) Determination of good solvent system for column chromatography4. Reaction......a) Overall reaction......b) Detailed reaction mechanism5. Purpose for performing TLC on this particular experiment

Reagent Table:

See experiment 1


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Precautions:See experiment 1 and also note the following:1. Do not look directly into UV light!2. Handling of reagents3. Handling of equipment

Apparatus:

See experiment 1 and refer to page 162 Figure 9.3 and 9.4 for diagram.


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Procedure:

Acetylsalicylic Acid Synthesis:1. To a small test tube add 138 mg of salicylic acid, a boiling chip, one drop of 85% phosphoricacid, and 0.3 mL of acetic anhydride.2. Mix contents of test tube very well and then heat the test tube on the steam bath for 5 min.3. Carefully add 0.2 mL of water to the test tube. Notice the evolution of heat.4. When the reaction appears to be over, add 0.3 mL of water and let test tube cool to roomtemperature.5. Place test tube in an ice bath. If recrystallization does not occur after a few minutes, then

scratch the inside of the test tube gently with a stirring rod to induce crystallization. Then replacein the ice bath for approximately 10 min.6. Collect the cooled product with a Buchner funnel.7. Allow product to air dry, obtain weight, determine the melting point. If melting point isdepressed recrystallize using hot water.8. Calculate the percent yield. Record IR, tabulate and analyze data.

Thin Layer Chromatography:1. Obtain a TLC plate from the desiccator on the side shelf (use gloves). On your plate, make alight pencil line about 1 cm from the bottom.2. Obtain a jar with a lid or aluminum foil.3. Obtain small amounts of the four standards (standards: aspirin, acetaminophen, ibuprofen,caffeine) and an unknown.


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4. Use a separate capillary tube to spot small amounts of each standard 1% solution on a plate.Do the same with the unknown.5. Put some 99.5% ethyl acetate/ 0.5% acetic acid solvent in the jar, ensuring that the solvent isnot deep enough to cover the pencil line.6. GENTLY place the TLC plate in the jar, making sure the 1 cm line is above the solvent in thejar.7. Allow the solvent front to almost reach the top of the plate before removing it.

8. Draw a pencil line where the solvent front is.9. Observe your plate under UV light or place in an iodine chamber for a few minutes and thencircle the spots that become apparent.10. Use the circled spots and a metric ruler to calculate Rfvalues for the standards and the

unknown.Be sure to make measurements from the center of the spots.11. Identify the unknown by comparison of its Rfvalue(s) to that of the standards.

Disposal:See experiment 1 and also note the following:1. Wash excess standard solutions down the drain with excess water.

2. Place TLC plates in the solid waste container.3. Solvents are to be placed in predesignated organic liquid waste container separate from otherorganic liquid waste.


Experiment 5:

Column Chromatography ofCholesterol and Cholesteryl Acetate

Prelab

Objectives:1. Synthesize cholesteryl acetate from cholesterol. Calculate theoretical yield2. Purify a reaction mixture of cholesterol and cholesteryl acetate using column chromatography

3. Monitor and confirm separation with TLC4. Determine the mass of each compound and obtain the melting point of each pure substance5. Determine ratio of cholesterol to cholesteryl acetate

Theory:Discuss and summarize the following:1. General (See TLC theory also)......a) Applications............1) Separating natural mixtures............2) Separating reaction components......b) Elutropic strength

......c) Adsorbents2. Packing the column


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......a) Uniformly

......b) Dry packing

......c) Slurry packing3. Interactions to consider......a) Polarity of sample......b) Polarity of eluting solvent......c) Activity of adsorbent



Apparatus:See experiment 1 and refer to Figure 10.1 on page 173.


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Procedure:

Cholesteryl Acetate Synthesis:1. To a large test tube add .75 mL Acetic Acid, 75 mg Cholesterol, .15 mL Acetic Anhydride, anda boiling chip.2. Gently reflux over a sand bath for no more than 30 minutes. While this is refluxing, proceed tostep 1 of the Column Chromatography section below.3. After reflux cool mixture for 5 to 10 minutes and then add 2 mL water.4. Extract product with two 2 mL portions of ether. Place the extracts in another test tube.5. To the ether extracts add one 2 mL portion of water, mix, and then extract the aqueous layerwith a pipette and discard.6. To the ether extracts add one 2 mL portion of 3M NaOH, mix, and then extract the aqueouslayer with a pipette and discard.7. Dry the ether solution with MgSO4 and decant the ether layer to another test tube.


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8. Spot a TLC plate with this ether solution and set aside.9. There should be approximately 4 mL of ether solution remaining. Carefully boil this solutionon a sand bath until all ether has evaporated. Dry, weigh, obtain mp, and determine % yield.10. Keep sample in test tube until next section.

Column Chromatography:1. Obtain Column setup figure 10.1 shown on page 173 of lab textbook.

2. To the column add enough silica gel to fill the column to about 1/2 to 2/3 of the way full.3. Pour the adsorbent into a 25 mL Erlenmeyer flask and add approximately 8 mL of hexane.4. Fill the column to about 3/4 of the way full with hexane.5. Swirl the flask with the adsorbent and hexane to cause the adsorbent to suspend in thesolvent and immediately pour into the column. (Do this very quickly and carefully; this is a veryimportant step.) You should be able to see the adsorbent holding in the funnel and slowly fallingdown to the bottom of the column. Once all adsorbent has fallen continue on.6. Allow the solvent to drain to about 5 mm from the top of the adsorbent. While this is drainingreturn to the reaction section above.7. Prepare a 25 mL solution of 70% hexane and 30% ether. Also prepare a 20 mL solution of

50% hexane and 50% ether.8. Take the product from the previous section and dissolve in just enough ether. This should beno more than a few drops.9. Pipette the ether solution containing the product into the column. If any gets on the sides ofthe column wash down with a few drops of hexane.10. Add to the column the 70/30 mixture and begin collecting 5 mL fractions.11. Collect the fractions in a 10 mL graduated cylinder. Once 5 mL has been collected, turn offthe release valve and pour the fraction into a small Erlenmeyer flask.12. Place the spot on a TLC plate for every fraction collected. The solvent for TLC should be a50/50 mixture of hexane and ether.

13. Dry the graduated cylinder and return to collecting fractions. While the next fraction isdraining, boil the fraction in the flask on a sand bath until all liquid has evaporated anddetermine if there is any residue.14. If a residue is present, remove it from the flask and collect in a small dry pre-weighedbeaker. (Note: There should be two distinct sections in the progression of the fractions whereyou will receive a residue. Collect these sections separately.)15. Once five 5 mL fractions has been collected, add the 50/50 mixture and collect 4 more 5 mLfractions. Use steps 11 through 14 for each fraction.16. Collect the separated products, dry, weigh, obtain mp's and determine % yield and therelative percentage of each product from the amount obtained after the reaction.



Experiment 6:

Oxidation of Cyclohexanol to Cyclohexanone byHypochlorite Oxidation


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Prelab

Objectives:1. Oxidize cyclohexanol to cyclohexanone using hypochlorite oxidation2. Isolate the cyclohexanone by extraction with ether3. Remove ether from cyclohexanone and determine the percent yield

4. Make a derivative of the product with 2,4-dinitrophenylhydrazine (2,4-DNP) and determine itsmelting point5. Record IR, tabulate and analyze data for pure cyclohexanone

Theory:Discuss and summarize the following:1. General......a) Definition of oxidation......b) Definition of reduction......c) Oxidizing agents2. Reaction

......a) Overall reaction

......b) Detailed reaction mechanism3. Information about making a derivative of a ketone using 2,4-DNP.4. Reasons for addition of sodium bisulfite, NaOH, and NaCl.





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Procedure:1. Into a small test tube:......a) Add 0.17 mL cyclohexanol (8 drops)......b) Add 0.10 mL acetic acid (5 drops)......c) Add 2.3 mL NaOCl2. Immediately cap the test tube and agitate it for 3 minutes.3. Place the test tube in a warm water bath (~45 C) for 15 minutes.4. Add 3 drops of sodium bisulfite solution.5. Add 0.4 mL of 6M NaOH.6. Stir the solution thoroughly.

7. Add 0.15 g of NaCl and shake until most of the salt dissolves.8. Extract with 0.4 mL Ether (16 drops).9. Collect and keep the top layer. Add this to a preweighed test tube.10. Repeat steps 8 and 9.11. Evaporate the ether off using a steam or hot water bath. (The ether has evaporated whenthe solution stops boiling.)12. Obtain the mass and percent yield of the product.13. Record IR, tabulate and analyze data for pure cyclohexanone14. Prepare the 2,4-DNP derivative of the product (cyclohexanone).......a) Mix 5 drops of 2,4-DNP and 5 drops of cyclohexanone in a small, dry test tube......b) Collect and dry the derivative15. Determine the melting point of the derivative and compare with the theoretical melting point(162 C).


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Experiment 7:

Reactions of Carbocations:Synthesis of Triphenylmethyl Bromide

Prelab

Objectives:

1. Form a trityl carbocation and ultimately triphenylmethyl bromide. Calculate theoretical yield2. Record mass, melting point, and calculate percent yield of crude substance3. Recrystallize from hexane and record mass and melting point. Compare melting point of thepure substance with that of the crude substance. Recalculate percent yield afterrecrystallization.4. Record IR, tabulate and analyze data

Theory:Discuss and summarize the following:1. General properties of carbocations

......a) Orbital hybridization......b) Orbital geometry

......c) Relative stabilities2. Reaction......a) Overall reaction......b) Reaction mechanism......c) SN1 and SN2 type reaction mechanisms




Click here to view how to place cap or top on syringe needle.
http://www.chem.sc.edu/faculty/handy/needle%20safety.mpg


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Procedure:1. Place 100 mg of triphenylmethanol into a small test tube.2. Add 2 mL of acetic acid and heat on a steam bath or hot water bath until the solid dissolves.Be sure to stir contents of test tube.3. Add 0.2 mL (~7-8 drops) of concentrated HBr.4. Heat solution for 5 - 10 minutes on a steam bath or in boiling water5. Let tube cool to room temperature and then cool in an ice bath. (The compound crystallizesslowly, allow adequate time for crystals to form.)6. Collect the cooled product with a Buchner funnel then wash with cold water and hexane.7. Dry the product and weigh it.

8. Calculate the percent yield and determine the melting point.9. Recrystallize the product from hexane and weigh pure product and determine the meltingpoint. Compare the melting points of the crude and pure products. Recalculate the percent yieldof pure product. Record IR, tabulate and analyze data.




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Experiment 8:

Synthesis and Reactions of AlkenesCyclohexene from Cyclohexanol

PrelabObjectives:1. Set up a fractional distillation apparatus2. Synthesize cyclohexene from cyclohexanol by dehydration3. Distill the cyclohexene product4. Record the barometric pressure5. Obtain more product by using a chaser solvent6. Fractionally distill the product again after several washings to purify cyclohexene.7. Obtain the mass of your product and the percent yield

8. Record IR of cyclohexene, tabulate and analyze data

Theory:Discuss and summarize the following:1. General......a) Dehydration......b) Catalysis......c) Chaser solvent2. Reaction......a) Overall reaction......b) Detailed mechanism



Apparatus:See experiment 1 and refer to Figure 5.11 on page 96.


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Click here to view proper venting of separatory funnel.

Procedure:1. Place 1 mL of water, 1 mL of concentrated sulfuric acid, and a boiling stone in a 25 mL roundbottom flask.2. Add 5 g of cyclohexanol to the flask.3. Cap the flask, shake it to mix the layers, and note the evolution of heat.4. Use the modified fractional distillation apparatus shown in figure 5.11 on page 96 of labtextbook. Be sure to use an insulating jacket on the apparatus.5. Note the initial effect of heating the mixture.6. Distill until the residue in the flask has a volume of about 2 mL and very little of the distillate isstill being condensed. Be sure to record the temperature range.

7. Let the assembly cool, remove the thermometer briefly, and pour 5 mL of the chaser solvent(toluene) into the top of the fractionating column through a long stemmed funnel.
http://www.chem.sc.edu/faculty/handy/separatory%20funnel%20venting.mpg


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8. Note the volume of the upper layer in the flask.9. Begin distillation process again and continue until the upper layer is reduced by half.10. Pour the cooled distillate into a small separatory funnel. Rinse the collection vessel with alittle toluene and pour it into the separatory funnel.11. Wash the mixture with an equal volume of brine (saturated sodium chloride solution).12. Separate the water layer and discard.13. Place the organic layer in a clean test tube and complete the drying process by adding a

micro-scoop of anhydrous magnesium sulfate.14. Before the final distillation, note the barometric pressure.15. Dry the boiling flask, condenser, and column.16. Decant the dried liquid into the round bottom flask through a small-stem funnel with a pieceof filter paper shaped like a cup to catch any particles of drying agent.17. Fractionally distill the product.18. Record the boiling range of the bulk of the cyclohexene. -the temperature range should notexceed 2 C -if the product is dried thoroughly, it will be clear and colorless19. Record the mass and calculate the percent yield. A typical yield is about 3 g.20. Record IR of cyclohexene, tabulate and analyze data.



Experiment 9:

Hydroboration of Styrene

Prelab

Objectives:1. Set up apparatus2. Synthesize phenylethanol from styrene by hydroboration3. Wash and dry product4. Obtain the mass of your product and the percent yield

5. Record IR of phenylethanol, tabulate and analyze data6. Save product for GC analysis

Theory:Discuss and summarize the following:1. General......a) Hydroboration......b) Oxidation2. Reaction......a) Overall reaction......b) Detailed mechanism

Reagent Table:


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See experiment 1


Apparatus:

Click here to view how to place cap or top on syringe needle.
http://www.chem.sc.edu/faculty/handy/needle%20safety.mpg


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Click here to view proper venting of separatory funnel.

StyreneBorane THF30% H2O2

3M NaOHEtherNaHCO3 sat sln

MgSO4

pH paper1 drying tube

oven dried Claisen Head1 septumoven dried 50 mL R-B Flask2 10 mL syringes, needlessmall stir barstir plate125 and 250 mL E-Flasks

Procedure
http://www.chem.sc.edu/faculty/handy/separatory%20funnel%20venting.mpg


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Part A: The reaction.1. Obtain the oven dried Claisen Head and 50 mL RB Flask.2. Place the drying tube over the Claisen Head upper opening directly over the Flask.3. Lightly grease and attach the 50 mL Flask, insure proper seal.4. Fill the assembly with Nitrogen gas and cover the open Claisen Head opening.5. Place the magnetic stir bar and 2.2 mL of Styrene into the Flask through the opening in theClaisen Head.

6. Place the second septa over the second Claisen Head opening.7. Clamp the assembly on a ring stand so that a stirplate and a beaker of ice can fit underneath.See drawing.8. Set the stirring to slow...2 or 3.9. Obtain 6 mL of the Borane THF soluiton with the 10 mL syringe and needle.10. Pierce the septa with the Borane THF syringe and leave it there throughout the addition.11. Add 1 mL of the Borane THF slowly every 5 minutes.12. Once all of the Borane THF has been added, let the solution stir for one hour. Keep ice on it.13. After an hour transfer the mixture / stir bar to a 125 mL E-Flask and emerse the flask in anice bath.

14. Place on the stir plate and gently stir.15. Dropwise add 2.0 mL of the 30% H2O2 with the second 10 mL syringe. No needle is

necessary.NOTE: After several drops check the pH. Adjust the pH to roughly 8 using the 3M NaOH insmall amounts.16. Let stir for 10 minutes after the all the peroxide has been added.17. Slowly add 20 mL of water to the reaction mixture. Then 10 mL of diethyl ether.18. Stir well then transfer the mixture to a clean 250 mL seperatory funnel; let the layersseperate.

Part B: The washing.1. Drain the water layer into the 250 mL E-Flask.2. Drain the ether layer into a 125 mL E-Flask and set aside.3. Return the water in the 250 mL E-Flask to the seperatory funnel and add 10 mL of diethylether.4. Stir the mixture using proper seperatory funnel techniques and let the layers settle.5. Repeat steps 20 and 21.6. With all the water layer out place the combined ether layers in the seperatory funnel andwash with 20 mL of a saturated NaHCO3 solution; again, use proper seperatory techniques..

7. Drain the aqueous layer then place the washed ether layer back into the 125 mL E-Flask.

Part C: The drying.1. Add MgSO4 to the ether flask.

2. Remove the ether layer from the MgSO4 and place into a small beaker.

3. Evaporate the ether layer using a sand bath. Do not overheat!4. Evaporate the residual THF using a vacuum setup apparatus.5. Record the mass and calculate the percent yield.6. Obtain IR spectra of product and save product for GC analysis.

Postlab

(See Experiment 1)


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Experiment 10:

Study of Natural Products: Alkaloids and SteroidsExtraction of Caffeine from Tea

PrelabObjectives:1. Extraction of caffeine from tea bags using hot water2. Separate and isolate caffeine from the hot aqueous solution by solvent extraction (free oftannin and other material)3. Record mass of caffeine isolated and Recrystallize crude caffeine from acetone/hexane4. Prepare caffeine salicylate - A solid derivative5. Identify caffeine by recording the melting of caffeine salicylate6. Record IR, tabulate and analyze data

Theory:Discuss and summarize the following:1. Natural Products - sugars, terpenes, steroids, alkaloids, amino acids.2. Discuss heterocyclic compounds.3. The purine nucleus - alkaloids.4. Lactams.5. Structure of caffeine and theophylline.6. Constituents of tea (tannins) tannic acid.7. Physiological Effects of Caffeine.





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Procedure:1. Place 10 tea bags in a 250 ml beaker.2. Add 75 ml of boiling water and allow to stand for 7-9 minutes.3. Decant the supernatant liquid into a 250 ml Erlenmeyer flask.4. Add 25 ml of hot water to the 250 ml beaker containing the tea bags. Swirl for 60 secondsand immediately decant the liquid portion into the Erlenmeyer flask containing the first extract.5. Cool the aqueous solution to near room temperature and extract it with 15 ml ofdichloromethane. [CAUTION!!! If done TOO vigorously, emulsions will form.] A gentlerocking/swirling motion will help extract the caffeine into the organic layer.6. Allow the mixture to stand for 4-5 minutes until you can distinguish the aqueous layer [top]

form the organic layer.7. Drain the lower dichloromethane [organic] layer containing caffeine into an Erlenmeyer flask[flask 1].8. Extract the aqueous solution in the separatory funnel with another portion [15 ml] ofdichloromethane.9. Drain the lower dichloromethane layer into an Erlenmeyer flask [flask 2]. Discard the toplayer.10. Combine the contents of Flask 1 and 2 dichloromethane extracts, the organic solutionscontaining the caffeine.11. Add 1 micro-scoop of magnesium sulfate to the combined dichloromethane extracts toremove traces of water. Swirl the contents and let it stand for 3-4 minutes.12. Decant or filter the dry dichloromethane solution containing caffeine into a clean, drypreviously weighed Erlenmeyer flask.


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13. Rinse the flask containing the magnesium sulfate with a small amount [2-3 ml] ofdichloromethane and combine this with the dichloromethane solution containing caffeine fromstep 12.14. Place a boiling stone in the Erlenmeyer flask containing the caffeine/dichloromethanesolution. Cautiously evaporate the dichloromethane by placing the Erlenmeyer flask on a steambath.15. After all the dichloromethane has been evaporated, collect the residue [caffeine] from the

Erlenmeyer flask. Record the mass.16. Recrystallize from Acetone/Hexane [mixed solvent system]. Dissolve the crude caffeine inthe minimum volume of hot acetone and carefully transfer the solution into a small Erlenmeyerflask [15 or 25 ml].17. Cautiously add hexane dropwise until the solution becomes cloudy. Set aside and allow thecontents of the flask to cool slowly to room temperature [10-15 min.]. Cool in an ice bath.18. Collect crystallized caffeine by suction filtration. [Use a Buchner funnel/side arm flask]. Washproduct with 0.5 ml of ice cold hexane. Drain liquid thoroughly.19. Identify the caffeine by forming a salt with salicylic acid and recording the melting point ofthe solid derivative.

......a) To 10 mg of caffeine in a weighed test tube [small] add 5.0 mg of salicylic acid and 0.5 mlof dichloromethane.......b) Heat the mixture to boiling on the steam bath and add hexane dropwise [CAUTION] untilthe mixture turns cloudy.......c) Insulate the test tube [wrap with paper towel and aluminum foil and cool slowly to roomtemperature.......d) Place the test tube cooled to room temperature in an ice bath.......e) Remove the solvent from the crystallized solid using a Pasteur pipette-record meltingpoint.

Disposal:.See experiment 1


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