SECTION 25.1 Introduction to Carbon Compounds

All substances can be classified as being either organic or inorganic. So far, our study ofchemistry has dealt mainly with inorganic compounds. Originally, organic substances were considered tobe those carbon compounds that were extracted from living things, while inorganic ones werecompounds that did not originate in living systems. An organic compound is defined as a substance thatcontains the element carbon. However, some compounds that contain carbon are considered to beinorganic. A better definition may be that organic compounds have a carbon base, that carbon is the"backbone" of the compounds.

Organic chemistry plays a very important role in our daily lives. Many of the clothes we wear aremade of rayon, dacron, nylon and orlon. These are all synthetic (man-made) organic compounds. Plasticsof all sorts are synthetic organic compounds, too. Petroleum is a naturally occurring organic substance,but synthetic rubber and plastics are two of the by-products of petroleum.

A large number of modern chemical materials have been developed from by-products ofpetroleum. In addition to these items, other materials such as sulfa drugs, penicillin, cortisone, perfumes,detergents, vitamins, pesticides, anesthetics, and many of the more modern antibiotics are among thecontributions made to society through a study of organic chemistry.

Throughout the 18th century, early chemists unsuccessfully tried to synthesize organicsubstances, starting with inorganic materials in their laboratories. Their failures gave rise to the "vital forcetheory" which stated that organic compounds could only be produced by a "vital force" which wasresponsible for life itself. This conclusion was closely tied to religious beliefs at the time. However, in1828, the German chemist, Friedrich Wohler, succeeded in synthesizing an organic compound known asurea, starting with two inorganic compounds. Thereafter, many other organic compounds weresynthesized in the same way in laboratories around the world. By 1850, the "vital force theory" wasdiscredited. From that time on, organic and inorganic chemistry were recognized as two major fields of thescience. There are over 90,000 known inorganic compounds. However, there are well over one millionknown organic compounds, and many more are being synthesized by chemists every year!

Why are there so many organic compounds? Well, carbon atoms can attach themselves to eachother in wide variety of ways. They can join together to form short or long chains, and they can form ringsof many kinds, as well:

C–C–C–C– C–C

C

C

C–C–C–C–C

CC–C– CC

C C

C C C

C C C C

CC

C

Carbon Chains Carbon Rings

The chains and rings can have branches and cross-links with atoms of other elements (mainly hydrogen)attached to the carbon atoms. Different arrangements of carbon atoms correspond to differentcompounds, and each compound has its own characteristic properties.

We are going to approach the subject of organic chemistry in terms of organic nomenclature.Nomenclature involves the naming of compounds. We will restrict ourselves to the simpler organiccompounds, because the more complex ones can get really complicated. You will be given a set of rulesto follow as you name compounds. These rules must be followed very carefully. Success in learningorganic nomenclature will involve some memorization on your part, but it will rely mainly on a logicalapproach to the problems presented.

The second most abundant element found in organic compounds is hydrogen. This chapter willdeal exclusively with compounds composed of only carbon and hydrogen. These are called

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hydrocarbons. These two elements can combine in countless ways. The structures of somehydrocarbons are shown below. The lines between the atomic symbols represent bonds. There arethree types of carbon to carbon bonds:

CH C H

H H

HH

C CH

HC C HH

single bond double bond triple bond

In each case you will note that carbon has a total of four bonds. This is because carbonhas four valence electrons. There are only a few carbon compounds in which carbondoes not have four bonds. One example is carbon monoxide. In this chapter,however, we will deal only with organic compounds in which the carbon atoms havefour bonds. After we have studied the hydrocarbons, Chapters 26 and 27 willintroduce you to the names and structures of organic compounds which contain otherelements in addition to carbon and hydrogen.

C Ocarbon

monoxide

Section 25.2 The Alkanes

The alkane family represents the simplest of the hydrocarbons. The general formula for thecompounds in this family is C nH2n+2, where "n" equals the number of carbon atoms in the molecule. Forexample, if you substitute a 1 into this formula you will get CH 4. Substitute a 2 and you will get C 2H6.These are the first two members of the family. The compounds in the alkane family are often calledsaturated compounds, which means that the molecules contain only single bonds between the carbonatoms.

Naming alkanes is fairly simple. The prefix in the name of each compound indicates the number ofcarbon atoms present. All alkanes have a suffix of -ane. A list of alkane prefixes is shown in Problem 1which has been partially completed for you. To make writing formulas or drawing structures easier, thehydrogens on the carbons are not always shown (note the structures on page 25-3); however, you shouldassume that enough hydrogen atoms are present to give each carbon atom 4 bonds.

Problem 1. Give the name and molecular formula for each compound below. Use the formula C nH2n+2to determine the formula, and add the suffix "ane" to the prefixes to obtain the names.

Prefix No. of Carbons Name Molecular Formula

a. meth- 1 ___methane__ ____CH4___

b. eth- 2 ____________ __________

c. prop- 3 ____________ ____C3H8___

d. but- 4 ____________ __________

e. pent- 5 ___pentane___ __________

f. hex- 6 ____________ __________

g. hept- 7 ____________ __________

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h. oct- 8 ____________ __________

i. non- 9 ____________ __________

j. dec- 10 ____________ ___C10H22__

In problem 1, you were writing molecular formulas. The kinds of formulas seen at the top of page25-4 are known as structural formulas. Writing structural formulas for organic compounds can become verycumbersome when all of the chemical bonds are included in the drawings. To remedy this problem,chemists have developed a shorthand method of writing structural formulas that involves condensing thestructures. In this shorthand method, the carbon atoms are still written separately (separated by hyphens),but the hydrogens which are bound to carbons are not. Instead, the hydrogens are written to the right ofthe carbon atoms to which they are bonded. This method of representing organic compounds is knownas the condensed structural formula. Study the examples of condensed structural formulas below.

C–C–C–C–HH H H H

H H H H

H

C–HH

H

H

Compound Structural Formula Condensed Structural Formula

methane

butane

CH4

CH3-CH2-CH2-CH3

Molecular Formula

CH4

C4H10

Problem 2. Complete the exercise below.

Compound Name Molecular Formula Condensed Structural Formula

a. methane ______CH4______ _____________CH4_____________

b. ethane _______________ _____________________________

c. propane _______________ _____________________________

d. butane _____C4H10______ ________CH3-CH2-CH2-CH3________

e. pentane _______________ _____________________________

f. hexane _______________ _____________________________

g. heptane _______________ _____________________________

h. octane _______________ _____________________________

i. nonane _______________ _____________________________

j. decane _______________ _____________________________

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Section 25.3 Alkyl Groups

Carbon chains are not rigid structures. They can bend and flex freely. When we say that an alkanehas a "straight" chain, we don't really mean straight. We mean that it is a continuous chain, rather than abranched chain. The two structures below both contain six carbon atoms. The one on the left is"straight," while the one on the right is branched.

CH3

CH2 CH2 CH2

CH2 CH3

CH3 CH2 CH2 CH CH3

CH3

This is one continuous chain of carbon atoms.

This is a branched chain of carbon atoms.

Now that you have mastered the straight-chain (or should we say "continuous" chain) alkanes, it istime to try something more challenging. Most alkanes exist as "branched" molecules such as the oneshown below. The longest continuous chain of carbon atoms in the molecule below is 7 (enclosed bybox). Therefore, the parent compound here is heptane. (Remember, the longest continuous chain is notnecessarily straight!)

CH3 CH2 CH2 CH CH3

CH3

CH

CH2

CH3CH2

The longest continuous chain contains 7 carbon's.

Having identified the parent compound, we must next identify the side chains. These side chains arecommonly called alkyl groups. Alkyl groups are attached to the longest continuous chain. When writtenalone, they are usually shown with a free-bonding site represented by a dash (like this: –CH 3). Thisbonding site represents a spot where a hydrogen atom has been removed. Thus, the general formula forthe alkyl groups is C nH2n+1. The free bonding site is what allows the alkyl group to bond to the parentcompound. Alkyl groups are named with the same prefixes as the alkanes themselves. The suffix ischanged from "ane" to "yl." Complete Problem 3 below by entering the formulas and condensedstructural formulas of the first six alkyl groups.

Problem 3. Complete the exercise below.

Name of Alkyl group Condensed Structural Formula

a. ___methyl _____________–CH3____________

b. __________ _____________________________

c. __________ _____________________________

d. ___butyl___ ________–CH2–CH2–CH2–CH3_____

e. __________ _____________________________

f. __________ _____________________________

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Depending on where the hydrogen atom is removed, the bonding site on some alkyl groups can changeposition. This would change the way in which the alkyl group bonds to the parent compound. Forexample, note the two alkyl groups shown below. Both are composed of three-carbon chains, but thebonding site differs:

CH2 CH2 CH3 CH3 CH CH3

propyl isopropyl

The compound on the left below has a propyl group attached to the parent compound which is octane.The compound on the right has an isopropyl group attached to the parent compound (heptane). Notethat all carbons in the molecules have four bonds.

CH3 CH2 CH2 CH CH2 CH3CH2 CH2

CH2

CH2

CH3

CH3 CH2 CH2 CH CH2 CH3CH2 CH2

CHCH3 CH3

Propyl group attached to an 8-carbon chain Isopropyl group attached to an 8-carbon chain

The carbon atoms on the end of the chain are called terminal carbons. When the bonding site of an alkylgroup occurs on a terminal carbon, the alkyl group is said to be "normal" and its name is sometimespreceded by the letter n. Thus, the propyl group above could also be called n-propyl (pronounced"normal propyl"). We will consider the use of this "n" prefix as optional. The other structure with thebonding site on the center carbon is called isopropyl .

SECTION 25.4 IUPAC Rules for Naming Alkanes

A system for naming organic compounds has been developed by the International Union of Pureand Applied Chemists (IUPAC). The system is accepted and used throughout the world. There is also amethod by which many organic compounds are given "common" names, but we will use only the IUPACsystem in this chapter. We will consider the rules one at a time and apply them to some practice problems.

RULE 1: Locate the longest continuous chain of carbon atoms. This will give you the name of the"parent" compound.

For example, if the longest chain contains four carbons, the parent compound is butane. The longestchains in the following two molecules are enclosed by a box:

CH3 CH2 CH2CH CH2 CH3CH2

CH2

CH2

CH3

CH

CH2 CH3CH2 CH2

longest continuous chain = 11 carbons

CH3 CH2 CH CH2 CH3CH2CH

CH2 CH3

CH2 CH3

longest continuous chain = 8 carbons

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Problem 4. Draw a box around the longest continuous chain of carbon atoms in the structures below,and name the parent compound for each one.

CH3 CH2 CHCH2 CH3

CH3

a. CH3 CH

CH3

CH3

b. c. CH3 CH2CHCH2 CH3

CH2 CH2 CH3

d. CH3 CH CH2 CH3

CH2 CH3

CH

CH2 CH3

e. CH3 CH CH2 CH3

CH2 CH3

CH3 CH2C CH3

CH3

f.

CH2

CH3

a. parent: __________________________ d. parent: __________________________

b. parent: __________________________ e. parent: __________________________

c. parent: __________________________ f. parent: __________________________

RULE 2: The name of the parent compound is modified by noting what alkyl groups are attached to thechain. Number the longest chain so that the alkyl group(s) will be on the lowest numbered carbons.

Note in the molecules shown below, that the longest chain should be numbered from right to leftin order to give the carbon which is bonded to the methyl group the lowest possible number:

CH3 CHCH2 CH3

CH3

1 2 3 4

Incorrect Numbering

CH3 CHCH2 CH3

CH3

4 3 2 1

Correct Numbering

The correct name of this compound is 2-methylbutane. The "2-" indicates that the methyl group isattached to the second carbon in the longest chain. Note that the name of the alkyl group is added to thatof the parent compound (butane) to form one word, and that hyphens are used to separate numbers fromalphabetical parts of the name.

Problem 5. For the following compounds, draw a box around the longest continuous carbon chain andname each molecule. The name of the molecule in part "b" is given to help you.

CH2CH3 CH CH2 CH3

CH3

a. Name: ___________________________________

CH2CH3 CHCH2 CH3b. Name: __3-ethylhexane______________________CH2

CH3 CH2

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CH2CH3 CHCH2c.

Name: ____________________________________

CH2 CH3CH2 CH2

CH3CH2 CH2

Name: ____________________________________

CH2CH3 CHCH2d. CH2 CH2

CH3CH3 CH

CH3CH2 CH2

RULE 3: When the same alkyl group occurs more than once in a molecule, the numbers of the carbons towhich they are attached are all included in the name. The number of the carbon is repeated as many timesas the group appears. The number of repeating alkyl groups is indicated in the name by the use of Greekprefixes for 2, 3, 4, 5, etc. (di, tri, tetra, penta, etc.).

To better understand rule 3, study the following examples.

CH3 CH CH2 CH3CH

CH3

CH3

is called 2,3-dimethylpentane

Note that numbers used in the name are separated from each other by commas, and note that thenumbers are separated from the rest of the name with a hyphen.

CH2CH3 is called 3,3-diethylhexaneCH2 C CH3CH2

CH2 CH3

CH2 CH3

Problem 6. Name the four molecules whose structures are drawn below.

a. CH3CH3 C

CH3

CH3

b. CH3CH3 C

CH2 CH3

CH3 CH2

CH2CH3 CH2 C CH3CH2

CH2 CH3

CH2 CH3

CH2 CH2c.

CH3 CH CH2 CH3CH2

CH CH3

CH CH3CH3

d.a.

b.

c.

d.

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RULE 4: If there are two or more different kinds of alkyl groups attached to the parent chain, name them inalphabetical order.

CH3 CH CH CH3CH2

CH3

CH3CH2

For example:is called 3-ethyl-2-methylpentane

It is NOT called 2-methyl-3-ethylpentane

However, when you are determining the alphabetical order, do not consider any Greek prefixes that arebeing used. For example:

CH3 C CH2 CH CH2 CH2 CH3

CH3

CH3 CH2 CH3is called 4-ethyl-2,2-dimethylheptane

It is NOT called 2,2-dimethyl-4-ethylheptane

Problem 7. Name the four molecules drawn below.

CH2 CH3

CH3 CH2 CH CH2 CH2 CH3CH2 CH CH2

CH3 CH2 CH3

a.

CH3 CH2 CH2 CH2 CH3CH2CHCH2b. C

CH3

CH3 CH2 CH3CH2

CH3

c. CH3 CH2 CH CH CH2 CH CH3

CH CH3CH3

CH2 CH3

d. CH3 CH CH2 CH CH2 CH2 CH CH3

CH3 CH3

RULE 5: To put the finishing touches on the name of an alkane, keep the following points in mind: (a)hyphens are used to separate numbers from names of substituents; (b) numbers are separated from eachother by commas; (c) the last alkyl group to be named is prefixed to the name of the parent alkane, formingone word; and (d) the suffix "-ane" indicates that the molecule is an alkane.

ACTIVITY 25.5 Using Molecular Models

The structure of alkanes is more understandable if you see them in three dimensions. We will usemolecular model kits for this purpose. Obtain a box containing a molecular model kit and determine whichparts represent carbon atoms, hydrogen atoms, carbon to carbon bonds, and carbon to hydrogen bonds.When you have done this, assemble models of the six molecules drawn in Problem 4. Pick up one of your

25-10 ©1997, A.J. Girondi

models and rotate one section of the model while holding the other. Do you see how rotation is possiblearound a single bond?_____________. Holding the model with both hands, bend and flex it a bit. Notethe bond angles between the carbons themselves and between the carbons and the hydrogens. Do yousee why these molecules are not really "straight" chains? ______________.

Because free rotation is possible around a single bond, what can you conclude about the 2 moleculesshown below?{1}____________________________ If you named these two molecules, what would

you discover?{2}________________________ What is the name?{3}___________________________

CH2 CH CH3CHCH3

CH3 CH3

CH2 CH CH3CHCH3

CH3

CH3

SECTION 25.6 Cyclic Alkanes

The compounds we have studied so far have been either "straight" or "branched" chains. Carbonatoms can also form rings which result in the formation of cyclic alkane molecules with the general formula,CnH2n. Naming the cyclic alkanes is not difficult, but the rules do differ a bit from those used to name thestraight and branched chained compounds.

The name of a cyclic molecule requires the addition of the prefix "cyclo" to the name of thehydrocarbon. Note the two condensed structural formulas below.

CH2 CH2

CH2

CH2 CH2

CH2 CH2

cyclopropane cyclobutane

To make cyclic compounds easier to draw, a shorthand notation is used in which the hydrogens andcarbons which are part of the ring are not represented at all. The rings are represented by lines, and acarbon atom is assumed to be present at each angle in the ring. The proper number of hydrogen atoms isassumed to be attached to each carbon.

For example:

cyclopropane cyclobutane cyclopentane cyclohexaneC3H6 C4H8 C5H10 C6H12

{4}__________________________ Name this compound

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Like the "straight-chained" compounds, cyclic molecules can also contain alkyl side chains. Thesame general rules for alkane nomenclature apply to the cyclics, except that all positions in a ring areequivalent, so a number is not needed to indicate the position of the alkyl group if there is only one alkylgroup on the ring. For example:

CH3 This is called methylcyclohexane

(It is NOT called 1-methylcyclohexane)

The carbon on which the alkyl group is located is automatically assumed to be number 1.

Problem 8. Name the cyclic molecules below.

CH2CH3CH2 CH3

CH2 CH3CH2

a._____________________ b._____________________ c._____________________

If there are two or more substituents on a ring, numbers must be used to indicate their positions.One of the substituents is always assigned position number 1, and starting at position 1, the chain isnumbered either clockwise or counterclockwise so as to give the other substituents on the ring thesmallest possible numbers. For example:

CH2 CH3

CH3

This is called 1-ethyl-2-methylcyclopentane

CH3

CH3

This is called 1,2-dimethylcyclopentane

(It is NOT called 1,5-dimethylcyclopentane)

CH3

CH2CH3

This is called 1-ethyl-4-methylcyclohexane

(You may have wanted to call it 4-ethyl-1-methylcyclohexane,but we chose to assign the number 1 position to ethyl since itcomes first, alphabetically, and since we get the samenumbers,1 and 4, either way.)

CH3

CH3

CH2CH3 This is called 4-ethyl-1,2-dimethylcyclopentane

25-12 ©1997, A.J. Girondi

In the last example, we assign position 1 to the carbon in the lower right corner and number the ringcounterclockwise. This gives the lowest possible set of numbers for the three substitutents on the ring.

CH2 CH3CH3

CH3

CH3

This is called 3-ethyl-1,1,2-trimethylcyclobutane

(We numbered clockwise this time)

In the molecule drawn above, if we assigned position #1 to the carbon which is bonded to the ethyl group,we would have had to number counterclockwise and name the molecule: 1-ethyl-2,3,3-trimethylbutane.This was avoided because it resulted in higher numbers.

The three structures drawn below are identical. Write the name: {5}_____________________________

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

Problem 9. Name the cyclic alkanes shown below:

CH2 CH3

CH2 CH3

CH3a.CH3

CH3

b.

c.CH2 CH3

CH3CH3

CH2 CH3

d. CH2 CH3

e. CH3

CH3

CH3 CH

CH3

CH3

CH3

f. g. CH2 CH2 CH3

CH3

a. __________________________________ e. __________________________________

b. __________________________________ f. __________________________________

c. __________________________________ g. __________________________________

d. __________________________________

25-13 ©1997, A.J. Girondi

ACTIVITY 25.7 Models of Cyclic Alkanes

Using a molecular model kit, construct the four cyclic molecules drawn below. The models giveyou some idea of what these cyclic compounds look like in three dimensions. You will also see the effectsof the bond angles on the shapes of the molecules. Be sure to include all needed hydrogen atoms, evenif they are not shown on the drawings.

cyclopropane cyclobutane cyclopentane cyclohexaneC3H6 C4H8 C5H10 C6H12

Do any of these cyclic compounds have what you might consider to be flat rings? If so, which one(s)?

{6}____________________________________________________________________________

Here is a summary of the rules used to name alkanes:

RULE 1: Locate the longest continuous chain of carbon atoms. This will give you the name of the"parent" compound.

RULE 2: The name of the parent compound is modified by noting what alkyl groups are attached to thechain. Number the longest chain so that the alkyl group(s) will be on the lowest numbered carbons.

RULE 3: When the same alkyl group occurs more than once in a molecule, the numbers of the carbons towhich they are attached are all included in the name. The number of the carbon is repeated as many timesas the group appears. The number of repeating alkyl groups is indicated in the name by the use of Greekprefixes for 2, 3, 4, 5, etc. (di, tri, tetra, penta, etc.).

RULE 4: If there are two or more different kinds of alkyl groups attached to the parent chain, name them inalphabetical order.

RULE 5: The put the finishing touches on the name of an alkane, keep the following points in mind: (a)hyphens are used to separate numbers from names of substitutents; (b) numbers are separated fromeach other by commas; (c) the last alkyl group to be named is prefixed to the name of the parent alkane,forming one word; and (d) the suffix "-ane" indicates that the molecule is an alkane.

SECTION 25.8 Naming Alkenes

Now that you are an expert on alkanes, let's take a look at the alkene functional group. Afunctional group is a feature of a class of compounds that is responsible for its characteristic properties.The functional group of the alkanes is the single bond. The functional group of the alkenes is the doublebond. Alkenes contain at least one double bond which exists between a pair of carbon atoms. Thegeneral formula for the straight-chained alkenes is CnH2n. The suffix to be used in the names of alkenes is"-ene." The rules for naming alkenes are the same as those for alkanes with a few additional restrictions.

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Additional Rules for the Nomenclature of Alkenes:

RULE 1: The chain chosen as the parent chain must contain the carbon–carbon double bond (C=C).

RULE 2: The parent chain must be numbered to give the carbon-carbon double bond the lowest possiblenumber.

RULE 3: The name of the alkene must contain a number to indicate the position of the double bond.

Note the example below. The longest carbon chain alkene is numbered correctly, giving the double bondthe lowest possible number.

CH2CH3 CH CH C CH3

CH2 CH3

CH3

12

3

4567 As we number the carbons, the first carbon involved in thedouble bond is #3, so the parent chain is called 3-heptene.Methyl groups are located on carbons #3 and #5.

3,5-dimethyl-3-heptene

A number is not used to locate the double bond in chains which are shorter than four carbons. Twoexamples are below.

CH2 CH2 This is called ethene, not 1-ethene

CH CH2CH3 This is called propene, not 1-propene

Why is it that these two molecules do not require the use of the number? {7}______________________

______________________________________________________________________________

Problem 10. Name the alkenes below. After you have located the longest chain containing the doublebond, be sure to number the chain so that the double bond gets the lowest possible number.

a. CH3 – CH2 – CH = CH2 ___________________________________________________________

b. CH3 – CH = CH – CH3 ___________________________________________________________

c. CH3 – CH2 – CH = CH – CH3 ___________________________________________________________

d. CH3 – CH2 – CH = CH – CH2 – CH3 ___________________________________________________________

e. CH2 = CH2 ___________________________________________________________

f. CH3 – CH = CH2 ___________________________________________________________

CH2 CH CHCHCH3

CH3

CH3

CH2g.

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CH CH3CH3 C

CH2 CH3

h.

CHCH3i. CH CH2

CH3

CH3CCHCH3j. CH CH2

CH2 CH3

CH2 CH3

SECTION 25.9 Naming Cycloalkenes

Cycloalkenes are named similarly to straight chained alkenes. The carbons in the ring that containthe double bond are always assigned the #1 and #2 positions, so numbers are used only to locate thepositions of substitutents attached to the ring - not to locate the position of the double bond. The generalformula for cyclic alkenes in CnH2n-2. Study the examples below.

CH3

CH3

CH3

cyclobutene 3-methylcyclohexene 3,4-dimethylcyclopentene

Problem 11. Name the following cycloalkenes.

a. CH2 CH3

b.

CH3

CH3

CH3 CH2

c.

CH3

CH3

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d.

CH CH3CH3

e.

CH2 CH2 CH3

CH3

CH3

f.

CH2 CH3

CH2 CH2 CH2 CH3

SECTION 25.10 Naming Alkynes

The functional group of the compounds known as the alkynes is a triple bond. The generalformula for straight-chained alkynes is CnH2n-2. Alkynes are named in much the same way as the alkenes,except that their names end with the suffix "-yne", signifying the triple bond. Once again, the triple bondmust be located within the parent chain, and it should be assigned the lowest possible number.

Additional Rules for the Nomenclature of Alkynes:

RULE 1: The chain chosen as the parent chain must contain the carbon- carbon triple bond.

RULE 2: The parent chain must be numbered to give the carbon-carbon triple bond the lowest possible number.

RULE 3: The name of the alkyne must contain a number to indicate the position of the triple bond.

As was the case with the alkenes, no number is used to locate the triple bond if the parent chain is shorterthan four carbons:

CH CH

ethyne

CH C CH3

propyne

CH C CH2 CH3

1-butyne

C CH3CH3 C

2-butyne

CCH3 C CH2 C CH3

CH3

1 2 3 4 5 6

For the example at right, the correct name is 5-methyl-2-hexyne

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Problem 12. Name the alkynes drawn below. Be sure to number the parent chain so as to give thetriple bond the lowest possible number.

a. CH C – CH2 – CH2 – CH3 __________________________________________

b. CH3 – CH2 – CH2 – C C – CH3 __________________________________________

c. CH3 – CH2 – C C – CH3 __________________________________________

d. CH3 – CH2 – CH2 – C CH __________________________________________

e. CH3 – C C – CH2 – CH2 – CH2 – CH3 _______________________________________________________________

f. CH3 CH C CH

CH3

g. CH3 C CHCH2 CH CH

CH3

CH2 CH3

CH2 CH3

h.

CH2

CH C C CH3

CH3

i. CH3 CH2CHC CH3C CH

CH3

CH2 CH3CH2

Table 25.1Summary of General Formulas forAlkanes, Alkenes, and Alkynes

Class of Compound General Formula

Straight-chained alkanes CnH2n+2Cycloalkanes CnH2nAlkenes CnH2nCycloalkenes CnH2n-2Alkynes CnH2n-2

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SECTION 25.11 Review Problems

Problem 13. The names of the compounds listed below are NOT correct. Using the incorrect name,draw the structural formula in the work area. Then write the correct name of each compound on the lineprovided.

Incorrect Name Correct Name Work Area

a. 4,4-dimethylhexane ___________________________

b. 2-n-propylpentane ___________________________

c. 1,1-diethylbutane ___________________________

d. 1,4-dimethylcyclobutane ___________________________

e. 3-methyl-2-butene ___________________________

f. 5-ethylcyclopentene ___________________________

g. 2-n-propyl-1-propene ___________________________

h. 2-isopropyl-3-heptene ___________________________

i. 2,2-dimethyl-3-butyne ___________________________

j. 5-octyne ___________________________

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Problem 14. Write condensed structural formulas for the following:

Name Condensed Structural Formula

a. 4-isopropyloctane

b. 3,4-dimethyl-4-n-propylheptane

c. 1,1-dimethylcyclobutane

d. 3-ethyl-3-heptene

e. 3-ethyl-2-methyl-1-hexene

f. 3-octene

g. 3,3-dimethyl-1-butyne

h. 4,4-dimethyl-2-pentyne

i. 3-n-butyl-2-ethylcyclohexene

j. 3,4-diethyl-4,6-dimethylnonane

25-20 ©1997, A.J. Girondi

SECTION 25.13 Answers to Questions and Problems

Questions:

{1} They are identical; {2} They would have the same name; {3} 2,4-dimethylpentane; {4} cyclooctane;{5} 1,1,2-trimethylcyclobutane; {6} cyclopropane and cyclobutane;{7} the double bond can only be in the #1 position

Problems:

1.a. meth- 1 methane CH4b. eth- 2 ethane C2H6c. prop- 3 propane C3H8 d. but- 4 butane C4H10e. pent- 5 pentane C5H12f. hex- 6 hexane C6H14g. hept- 7 heptane C7H16h. oct- 8 octane C8H18i. non- 9 nonane C9H20j. dec- 10 decane C10H22

2.a. methane CH4 CH4b. ethane C2H6 CH3–CH3c. propane C3H8 CH3–CH2–CH3d. butane C4H10 CH3–CH2–CH2–CH3e. pentane C5H12 CH3–CH2–CH2–CH2–CH3f. hexane C6H14 CH3–CH2–CH2–CH2–CH2–CH3g. heptane C7H16 CH3–CH2–CH2–CH2–CH2–CH2–CH3h. octane C8H18 CH3–CH2–CH2–CH2–CH2–CH2–CH2–CH3i. nonane C9H20 CH3–CH2–CH2–CH2–CH2–CH2–CH2–CH2–CH3j. decane C10H22 CH3–CH2–CH2–CH2–CH2–CH2–CH2–CH2–CH2–CH3

3.a. methyl –CH3b. ethyl –CH2–CH3c. propyl –CH2–CH2–CH3d. butyl –CH2–CH2–CH2–CH3e. pentyl –CH2–CH2–CH2–CH2–CH3f. hexyl –CH2–CH2–CH2–CH2–CH2–CH3

4. a. pentane; b. propane; c. hexane; d. heptane; e. pentane; f. pentane

5. a. 2-methylpentane; b. 3-ethylhexane; c. 4-propyloctane; d. 4-isopropylnonane

6. a. 2,2-dimethylpropane; b. 3,3-dimethylpentane; c. 4,4-diethyloctane; d. 2,3,4-trimethylheptane

7. a. 4-ethyl-6-methylnonane; b. 6-propyl-3,3-dimethylnonane; c. 4-ethyl-5-isopropyl-2-methylheptane;d. 4-ethyl-2,7-dimethyloctane

25-22 ©1997, A.J. Girondi

8. a. ethylcyclobutane; b. ethylcyclopropane; c. propylcyclopentane (or n-propylcyclopentane)

9. a. 1,3-diethyl-5-methylcyclohexane; b. 1,2-dimethylcyclopropane;c. 1-ethyl-2,3-dimethylcyclopropane; d. 1,2-diethylcyclopentane; e. 1,3,5-trimethylcyclohexane;f. 1-isopropyl-3-methylcyclobutane; g. 1-methyl-2-propylcyclooctane

10. a. 1-butene; b. 2-butene; c. 2-pentene; d. 3-hexene; e. ethene; f. propene;g. 3,5-dimethyl-1-hexene; h. 3-methyl-2-pentene; i. 3-methyl-1-butene; j. 4,4-diethyl-2-hexene

11. a. 4-ethylcyclopentene; b. 6-ethyl-3,3-dimethylcyclohexene; c. 1,3-dimethylcyclobutene;d. 3-isopropylcyclopropene; e. 3,5-dimethyl-6-propylcyclooctene; f. 2-butyl-3-ethylcyclobutene

12. a. 1-pentyne; b. 2-hexyne; c. 2-pentyne; d. 1-pentyne; e. 2-heptyne; f. 3-methyl-1-butyne;g. 4-ethyl-3-methyl1-hexyne; h. 3,3-dimethyl-1-hexyne; i. 6-methyl-4-propyl-2-heptyne

13.

a. 3,3-dimethylhexane CH3 CH2 CH2 C CH2 CH3

CH3

CH3

b. 4-methylheptane CH3 CH2 CH2 CH2 CH3CH CH2

CH3

c. 3-ethylhexane CH3 CH2 CH CH2 CH3CH2

CH2 CH3

d. 1,2-dimethylcyclobutane

CH3

CH3

e. 2-methyl-2-butene CH3CH3 CH C

CH3

f. 3-ethylcyclopentene CH2CH3

g. 2-methyl-1-pentene CH2 C CH2 CH3CH2

CH3

h. 2,3-dimethyl-4-octene CH3 CH CH CH CH CH2 CH2 CH3

CH3

CH3

25-23 ©1997, A.J. Girondi

i. 3,3-dimethyl-1-butyne CH3 C C CH

CH3

CH3

j. 3-octyne C C CH2 CH3CH2CH2CH2CH3

14.

CHCH3 CH2CH2 CH2 CH2 CH3CH2

CH CH3CH3

a.

CH3 CH2 CH2 CH3CH2b.

CH2 CH2 CH3

CH C

CH3 CH3

c.CH3

CH3

CH3CH2CH2CH3 CH2 C CH

CH2 CH3

d.

CH3CH2 CH2CHe. C

CH3

CH2 CH3

CH2

CH3f. CH2 CH CH CH2 CH2 CH2 CH3

g. C C CH3

CH3

CH3

CH

h. C C CH3

CH3

CH3

CCH3

25-24 ©1997, A.J. Girondi

i. CH2 CH3

CH2 CH2 CH3CH2

Cj. CH3 CH2 CH CH2

CH2

CH CH2 CH3CH2

CH3 CH3

CH2 CH3

CH3

25-25 ©1997, A.J. Girondi

SECTION 26.1 Alcohols

Alcohols are molecules in which an alkyl group is attached to a hydroxy group (–OH). Thehydroxy group is responsible for the characteristic properties of alcohols so we refer to it as the functionalgroup for alcohols. There are three different methods for naming alcohols, but we will use only the IUPACsystem. The rules that you used for naming alkanes and alkenes (in Chapter 25) are similar to those usedfor the alcohols. The modified rules are listed below.

Additional Rules for the Nomenclature of Alcohols:

RULE 1: Locate the longest continuous chain of carbon atoms which contains the "hydroxy" (–OH) group. This chain will serve to identify the parent compound.

RULE 2: Number the chain so as to give the carbon atom which is bonded to the –OH group the lowest possible number.

RULE 3: A number is included before the name of the parent compound to indicate the position of the –OH group.

RULE 4: The suffix "ol" is added to the name to indicate that the molecule is an alcohol.

Study the examples below. Note that the number indicating the position of the –OH group is not used ifthe chain is shorter than 3 carbons. Why? {1}_____________________________________________

______________________________________________________________________________

CH3OH

CH3CH2OH

CH3CH2CH2OH

CH3CHOHCH3

OH

CH3 OH

CH2 OHCH3

CH2 OHCH2CH3

CH

OH

CH3 CH3

C

C C

C C

OH

HH

H

H

H

H

HH H

methanol

ethanol

1–propanol

2–propanol

cyclopentanol

Name Formula Condensed Structural Formula

26–3 ©1997, A.J. Girondi

In addition, you see in the example above that the position of the –OH ("hydroxy") group is not included inthe names of cyclic alcohols, either. Why not? (Remember that this is also the case for the double bondin cyclic alkenes. {2}________________________________________________________________

(The hydroxy group,–OH, should not be confused with the hydroxide ion, OH1–. The hydroxy group hasthe same formula, but it is not an ion.)

Problem 1. Name the alcohols given below.

a. CH3–CH2–CH–CH2–CH3

OH

b. CH3–CH–CH2–CH3

OH

c. CH3–CH–CH–CH3

OH

CH3

d. CH3–CH–CH2–CH–CH–CH3

OH

CH3

CH3

e. CH3–CH2–CH–CH2–CH2–CH2–OH

CH2 CH3

f.OH

g.OH

CH3

CH3

h. CH3 OH

i.OH

CH2 CH3CH3

26–4 ©1997, A.J. Girondi

j. CH3–CH–CH3

OH

This compound is commonly called "rubbing alcohol." Give its IUPAC name.

Problem 2. Draw the condensed structural formulas for the following.

a. 4,4–dimethyl–2–hexanol b. cyclopropanol

c. 2,3–diethylcyclohexanol d. 3,4–diethyl–2–heptanol

Section 26.2 Ethers

Ethers are compounds which contain an oxygen atom bonded to two carbon atoms within thecarbon chain. The functional group is the C–O–C arrangement found within the chain. When you look atan ether molecule, you will see an alkyl group on each side of the oxygen. For example,CH3–CH2–O–CH3 has an ethyl group on the left of the oxygen atom and a methyl group on the right. The"common name" for this molecule is methyl ethyl ether. Although common names are still frequently usedfor ethers, we will stick to our "game plan" and use the IUPAC system.

CH3–CH2–O–CH3

Parent compound is "ethyl"

Functional group is "methoxy"

In the IUPAC system, the larger of the two alkyl groups attached to the oxygen is considered to bethe parent compound. For the ether mentioned in the last paragraph above, the parent compound wouldbe ethane. The smaller alkyl group and the oxygen atom are considered to be a substituent group on theparent compound. The –O–CH 3 group is the substituent and it is called "methoxy." So the name of thatether is methoxyethane. If the substituent had been CH 3–CH2–O–, it would have been called "ethoxy."Collectively these functional groups of the ethers are known as alkoxy groups. Only one modified ruleneeds to be mentioned here regarding the nomenclature of ethers.

26–5 ©1997, A.J. Girondi

Additional Rule for the Nomenclature of Ethers:

RULE: For ethers with parent chains that contain 3 or more carbon atoms, a number is included to indicate the position of the alkoxy group.

Study the examples below.

CH3–O–CH3 CH3–CH2–O–CH2–CH3 CH3–O–CH2–CH2–CH3 CH3–O–CH–CH3

CH3

methoxymethane ethoxyethane 1–methoxypropane 2–methoxypropane

Problem 3. Name the following ethers:

a. CH3–O–CH2–CH2–CH2–CH3 ___________________________________

b. CH3–CH2–CH2–O–CH2–CH2–CH3 ___________________________________

c. CH3–CH2–O–CH–CH2–CH2–CH3 _____________________________________________________

CH3

Draw condensed structures for the following ethers:

d. methoxycyclohexane e. 3–methoxycyclopentene

f. 4–ethoxynonane g. 2–isopropoxybutane

Section 26.3 Aldehydes and Ketones

The next two organic functional groups we will study are those of the aldehydes and ketones.Aldehydes and ketones contain a carbonyl group, which consists of an oxygen atom which isdouble–bonded to a carbon atom. There are two kinds of carbonyl groups involved here. In aldehydes, atleast one hydrogen is attached to the carbonyl carbon, while in ketones, two carbon atoms are alwaysattached to the carbonyl carbon.

C

O

C

O

H C

O

CC

carbonyl group aldehyde group ketone group

26–6 ©1997, A.J. Girondi

It is helpful to note that in an aldehyde the carbonyl carbon is always a terminal carbon, which means italways occurs at one end of the carbon chain. In ketones, the carbonyl carbon is never a terminal carbon.The nomenclature of aldehydes requires a few rule modifications:

Additional Rules for the Nomenclature of Aldehydes:

RULE 1: The longest continuous chain containing the aldehyde group is considered to be the parent compound.

RULE 2: The carbonyl carbon is part of the parent chain and is always considered to be in the #1 position.

RULE 3: The suffix "al" is added to the name of the parent compound to indicate that the compound is analdehyde.

Note the examples of aldehydes shown below. You see that no number is needed to indicate theposition of the functional group since it is always at position #1.

CH3–CH2 O

H

C CH3–CH–CH2–CH2 O

H

C

CH3

CH2–CH2–CH2–CH–CH2–CH2–CH–CH2–CH3C

O

H

CH2–CH3 CH3

propanal 4–methylpentanal

5–ethyl–8–methyldecanal

The nomenclature of ketones also requires a few rule modifications.

Additional Rules for the Nomenclature of Ketones:

RULE 1: The longest continuous chain containing the ketone group is considered to be the parentcompound.

RULE 2: A number is included before the name of the parent compound to indicate the position of theketone group. The chain is always numbered so that the carbonyl carbon has the lowestpossible number.

RULE 3: The suffix "one" is added to the name of the parent compound to indicate that the compound is a ketone.

For example:

C

O

CH3CH3 C

O

CH2CH2

CH3

CH3 CH3–CH–CH2–CH2–CH2–C O

CH3CH3

2–propanone 3–pentanone 6–methyl–2–heptanone

26–7 ©1997, A.J. Girondi

Why would it be impossible for a ketone to have a name like 3–methyl–1–hexanone? {3}_____________

_____________________________________________________________________________

Problem 4. Name the molecules shown below.

C

O

CH3CH2CH3a.

C

O

HCH2CHCH3

CH3

b.

CH3–CH2–CH–CH–CH3

CH3

O

H

C

c.

CH3–CH–CH–CH2– OC

CH3

CH3

CH2–CH3

d.

OC

CH3–CH2–CH2

CH2–CH2–CH–CH3

CH3e.

Section 26.4 Organic Acids

Organic acids are molecules that contain a carboxyl group (sometimes called a carboxylic acidgroup). This functional group consists of a carbon which is doubled bonded to an oxygen atom, as wasthe case with aldehydes and ketones. However, in an acid a hydroxy group (–OH) is also bonded to thatsame carbon. Be careful not to confuse organic acids with alcohols, aldehydes, or ketones. As was thecase with aldehydes, this functional group always occurs on a terminal carbon of the parent chain.Therefore, a number is not used in the name to locate the carboxyl group.

Additional Rules for the Nomenclature of Carboxylic Acids:

RULE 1: The longest continuous chain containing the carboxyl group is considered to be the parent compound.

RULE 2: The carboxyl carbon is part of the parent chain and is always considered to be in the #1 position.

RULE 3: The suffix "oic" is added to the name of the parent compound, and the word "acid" is added to the name.

26–8 ©1997, A.J. Girondi

For example:

COH

H

O

COH

O

CH3 CH3–CH–CH2–CH2 COH

OCH3

methanoic acid ethanoic acid 4–methylpentanoic acid

Acids also have common names. For example, ethanoic acid is also called acetic acid or "vinegar." We willwork only with the IUPAC names.

As you attempt to name the carboxylic acids, note that the carboxyl group is written in shorthand as–COOH in the condensed structural formulas.

Problem 5. Name the organic acids below.

b. CH3–CH2–CH2–CH2–CH2–COOH __________________________________

c.__________________________________

d.__________________________________

e. __________________________________

f. __________________________________

CH3–CH2–CH2

CH3–CH2–CH–CH2–COOH

CH3–CH–CH2–CH2–CH–CH2–CH2–COOH

CH3 CH3

CH–CH2–COOH

CH3

CH3

CH3–C–CH2–CH2–COOH

CH2–CH2–CH2–CH3

CH2–CH2–CH2–CH3

a. CH3–CH2–CH–CH2–CH2–COOH __________________________________

CH2 – CH3

Section 26.5 Esters

CO

O R

Esters are organic compounds which are very common in nature. Forexample, fats and oils are esters. Esters are also responsible for many of the odorsand flavors of fruits. Oil of wintergreen and aspirin are esters. Esters can beconsidered to be derivatives of carboxylic acids. The functional group of esters lookssimilar to the carboxyl group of acids, except that the hydrogen atom on the hydroxygroup is replaced with an organic group such as an alkyl group. The letter "R" in thestructure at right represents some organic group (methyl, ethyl, etc.).

26–9 ©1997, A.J. Girondi

carboxyl group general ester group sample ester group

C

O

O R

C

O

O CH3

C

O

O H

Esters are named by first naming the "R" group followed by the name of the acid portion. The suffix of theacid derivative is then changed from "–ic" to "–ate." For example, in the leftmost structure below, theparent acid is ethanoic acid. The "R" group is methyl, so the name of the ester is methyl ethanoate. In thecenter structure, the parent acid is butanoic, while the "R" group is ethyl, so the ester is named ethylbutanoate. Notice that the names of esters consist of two words, while the names of most of the previoustypes of compounds you have studied consisted of only one word.

CO

O– CH3

CH3 – CO

O– CH2 – CH3

CH3 – CH2 – CH2 – CO

O– CH2 – CH3

H –

methyl ethanoate ethyl butanoate ethyl methanoate (pineapples) (artificial rum flavor)

Artificial flavors of strawberry, apple, raspberry, cherry, etc., are made from esters.

Additional Rules for the Nomenclature of Esters:

RULE 1: Determine the name of the "R" group.

RULE 2: Place the name of the "R" group in front of the name of the parent acid, forming two words.

RULE 3: Determine the name of the parent acid, and change its suffix from "–ic" to "–ate." Drop the word "acid."

Problem 6. Name the esters below.

CO

O – CH2 – CH2 – CH3

CH3 – CH2 – CH2 –a. CO

O– CH3

CH3 – CH2 – CH2 – CH2 –b.

CO

O – CH2 – CH2 – CH2 – CH3

CH3 – CH2 – c. CO

O– CH – CH3

CH3 –

CH3

d.

26–10 ©1997, A.J. Girondi

CO

O– CH2 – CH2 – CH3

CH3 – CH2 – CH2 – CH2 –e. CO

O– CH2 – CH2 – CH2 – CH2 – CH3

H –f.

Section 26.6 Amines

Amines are organic compounds which are related to ammonia (NH3). All amines have the elementnitrogen in them. There are three basic kinds of amines:

1. In primary amines one hydrogen atom in ammonia has been replaced by an alkyl group.

2. In secondary amines two hydrogen atoms in ammonia have been replaced by two alkyl groups.

3. In tertiary amines all three hydrogen atoms in ammonia have been replaced by three alkyl groups. Examine the examples below:

CH3 N H

H

CH3 CH2 N

H

CH2 CH3 N CH2 CH3CH3

CH CH3CH3

A Primary Amine A Secondary Amine A Tertiary Amine

According to the IUPAC system, primary amines are named by treating the –NH2 (amino) group inthe molecule as a substituent group on the longest (parent) chain of carbon atoms. For example, theprimary amine shown above is called aminomethane . Two more examples are shown below.

CH3 – CH2 – CH – CH2 – CH2 – CH3

N HH CH3 – CH – CH2 – CH – CH2 – CH2 – CH3

CH3 NH2

3–aminohexane 4–amino–2–methylheptane (a primary amine) (a primary amine)

Secondary and tertiary amines are named according to a "common" naming system. Primaryamines can have either IUPAC or common names. Amines are the only organic compounds for which wewill learn common names. In the common system, amines are named by adding the names of the alkylgroup(s) attached to the nitrogen atom to the word "amine." In the past, the alkyl groups were named inorder of size (smallest first) instead of in alphabetical order is normally done in the IUPAC system.However, today we follow the IUPAC rules and name the alkyl groups in alphabetical order. For example,the name of the secondary amine shown above is diethylamine. The name of the tertiary amine above isethylisopropylmethylamine. Study the examples below. Note that the primary amine can have two names.

26–11 ©1997, A.J. Girondi

CH3 N CH3

CH3

NH

CH2

CH3

CH2 CH3

NH

CH3CH2 CH2 CH2 CH2

H trimethylamine methylpropylamine pentylamine (common)

1–aminopentane (IUPAC)a tertiary amine a secondary amine a primary amine

Additional Rules for the Nomenclature of Amines:

RULE 1: In primary amines only, the IUPAC system treats the NH2 (amino) group as a substituent group on the parent chain.

RULE 2: When using the common naming system, the names of the alkyl groups which are attached to the nitrogen atom are listed in alphabetical order and are attached to the suffix "amine" to form one word. Greek prefixes are used if specific alkyl groups occur more than once in a molecule. Name the amines below. Where two lines are present, give two names.

Problem 7. Name the amines below. Where two lines are present, give two names.

CH2CH3 N CH3

CH3a.

CH2CH3 N CH3

Hb.

c. CH3 – CH2 – CH2 – CH – CH2 – CH – CH3

CH3 NH2

CH2CH3 CH2 CH2 CH2

NH CH3

d.

CH3 CH2 N CH2 CH3

CH2 CH3e.

CH3 – CH – CH2 – CH2 – CH2 – CH2 – CH2 – NH2

CH2 CH3f.

g.CH3 CH3

NH2

CH

26–12 ©1997, A.J. Girondi

h.NH2

Section 26.7 Amides

You are already familiar with the carboxyl group which is the functional group of a carboxylic acid. Ifyou replace the hydroxy group (–OH) in the carboxyl group with an amino group (–NH 2), you get thefunctional group of a class of organic compounds known as primary amides.

CO

O H

CO

NH2

carboxyl group amide group

There are three classes of amides just as there were for amines, but we will consider only primaryamides, and we will name them according to the IUPAC system. Amides are considered to be derivativesof carboxylic acids, which means they are formed from acids. Thus, the amides are named as derivatives ofacids. To name an amide, simply identify the name of the organic acid from which the amide was derived,and change the "–oic" suffix in the acid's name to "–amide." The examples of amides shown below werederived from ethanoic, propanoic, and butanoic acids.

C

O

CH3

NH2

C

O

CH2

NH2

CH3 C

O

CH2

NH2

CHCH3

CH3

ethanamide propanamide 3–methylbutanamide

Additional Rules for the Nomenclature of Amides:

RULE 1: Identify the carboxylic acid from which the amide was derived and change the suffix of the acidname from "–oic" to "–amide," and drop the word acid.

RULE 2: Add the names of any alkyl groups to the name of the parent compound, forming one word.

Problem 8. Name the amides shown below. Note that the amide functional group is written inshorthand as CONH2.

a. HCONH2 b. CH3–CH2–CH2–CH2–CONH2

__________________________________ ____________________________________

26–13 ©1997, A.J. Girondi

CH3–CH2–CH–CH2–CH2–COHN2

CH2–CH3 CH3–C–CH2–CONH2

CH3

CH3

__________________________________ ____________________________________

c. d.

CH3–CH2–CH–CH2–CH–CH2–CONH2

CH2–CH3

CH3

CH3–CH–CH2–C–CH2–CONH2

CH3 CH3

CH3

e. f.

__________________________________ ____________________________________

Section 26.8 Halogenated Hydrocarbons

The last group of compounds we are going to discuss includes some that are of great importanceand interest today. Included are the chlorofluorocarbons that are used in refrigeration and air conditioningsystems and which are thought to be involved in the depletion of ozone in the upper atmosphere.

This class of organic compounds is known as the halogenated hydrocarbons. In addition to theiruse in refrigerants they are used as solvents, aerosol sprays, antiseptics, dry cleaning fluids, insecticides,herbicides, and anesthetics. Most of these compounds are synthetic (human– made).

In these compounds, the functional group is a single atom of a halogen such as fluorine, chlorine,bromine, or iodine. In the IUPAC system, the halogen atoms are considered to be substituents on theparent chain. The "–ine" suffix of the halogen's name is dropped and the letter "o" is added before beingadded to the name of the parent compound. For example, fluorine becomes "fluoro," chlorine becomes"chloro", bromine becomes "bromo," and iodine becomes "iodo." Note the examples below.

H–C–I

H

H

H–C–C–Cl

H H

HH

H–C–C–C–Br

H H

HH

H

H

H–C–C–C–C–C–C–C–C–H

H F

HH

H

H

H I H H H

F H H H H

iodomethane chloromethane 1–bromopropane 2,4–difluoro–5–iodooctane

CH3–I CH3–CH2–Cl CH3–CH2–CH2–Br CH3–CHF–CH2–CHF–CHI–CH2–CH2–CH3

Numbers are not used to indicate the position of a single halogen atom substituent unless the parentcarbon chain is longer than 2 atoms; however, if more than one halogen atom substituent is present, thennumbers are needed on a two–carbon chain, too! Study the following examples.

H–C–C–Cl

H

HH

Cl

Cl–C–C–Cl

H H

HH

H–C–H

Br

F1,1–dichloroethane 1,2–dichloroethane bromofluoromethane

26–14 ©1997, A.J. Girondi

Additional Rules for the Nomenclature of Halogenated Hydrocarbons:

RULE 1: Drop the "–ine" suffix from the name of the halogen atom(s) and add a suffix consisting of the letter "o".

RULE 2: Add the altered name(s) of the halogen atom(s) to that of the parent compound.

Problem 9. Name the halogenated compounds below.

a. CH3 – CH2 – CH – CH – CH3

Cl

Cl

b. F – C – F

H

H

c. CH3 – CH – CH – CH – CH2 – CH3

I

F Br

d. CH3 – CH – CH = CH2

Br

e. CH2 – CH2 – CH2 – Br

CH2 – CH2 – CH2 – CH3

f. Cl – C – Cl

F

F

Problem 10. Write condensed structural formulas (such as those shown above) for the following.

a. tetrafluoromethane

b. 1,1,1–trichloroethane

26–15 ©1997, A.J. Girondi

c. chlorocyclopentane

d. 1,3–difluoro–2–iodocyclohexane

e. 3,4–dibromo–6–methyl–1–heptyne

f. 3–chlorocyclopentene

g. 2,3–dichlorocyclobutene

Section 26.9 A Review of Organic Nomenclature

The remainder of this chapter consists of a review of nomenclature of the various classes oforganic compounds which you have studied.

Problem 11. Some of the names of the six compounds listed below are incorrect. If the name iscorrect, respond with "O.K." If the name is incorrect, provide the correct name.

a. 3–chloropentane ___________________________________

b. 1,1–dimethyl–1–propanol ___________________________________

c. 2,2,3–trimethyl–4–bromoheptane ___________________________________

d. 4–methyl–4–hexanol ___________________________________

e. 2,2–dimethyl–3–chloro–3–butanol ___________________________________

f. 1–ethyl–2–ethanol ___________________________________

26–16 ©1997, A.J. Girondi

Problem 12. Draw condensed structural formulas for the compounds named below.

a. 1,3,5–tribromocyclohexane b. 2,3–dichlorobutane

c. 2–ethyl–3–methyl–1–pentanol d. 1–ethoxypropane

e. 2–iodo–3–isopropylcyclohexanol f. 3,3–dimethylbutanal

g. 2–methoxy–3–heptanone h. 3–pentanone

i. 3,4–diethylhexanal j. 2,4–difluorohexanoic acid

k. 2–hydroxybutanoic acid l. ethyl ethanoate

m. n–propyl octanoate n. 4–bromo–3–chloroheptane

26–17 ©1997, A.J. Girondi

o. ethylmethylamine p. isopropyldimethylamine

q. propanamide r. 3–methylbutanamide

s. 4–chloro–2–pentanone t. 2,3,4–triiodopentanoic acid

Problem 13. Give another name for each of the following:

a. ethylamine _____________________________________________

b. isopropylamine _____________________________________________

Section 26.11 Learning Outcomes

Before leaving this chapter, read through the learning outcomes listed below. Place a checkbefore each outcome when you feel you have mastered it. When you have completed this task, arrangeto take any quizzes or exams on this chapter.

_____1. Given their names or condensed structural formulas, distinguish between alcohols, ethers, aldehydes, ketones, organic acids, esters, amines, amides, and halogenated compounds.

_____2. Given their names, draw condensed structural formulas for the classes of compounds given in outcome 1 above.

_____3. Given their condensed structural formulas, give the IUPAC names of molecules belonging to the classes of compounds listed in outcome 1 above.

_____4. Given their condensed structural formulas, give the common names of secondary and tertiary amines.

26–18 ©1997, A.J. Girondi

Section 26.12 Answers to Questions and Problems

Questions:

{1} Only one position is possible for the –OH group; {2} Whatever position the –OH group occupies isautomatically #1 if the compound is named as an alcohol; {3} Such a compound would be an aldehyde, nota ketone

Problems:

1. a. 3-pentanol; b. 2-butanol; c. 3-methyl-2-butanol; d. 4,5-dimethyl-2-hexanol;e. 4-ethyl-1-hexanol; f. cyclobutanol; g. 2-methylcyclohexanol; h. 3,4-dimethylcyclopentanol;i. 2-ethyl-3-methylcyclopropanol; j. 2-propanol

CH3 – CH – CH2 – C – CH2 – CH3

OH CH3

CH3

OH

CH2 – CH3

CH2 – CH3

OH

CH3 – CH – CH – CH – CH2 – CH2 – CH3

CH2 – CH3

CH2 – CH3

OH

2. a. b.

c. d.

3. a. 1-methoxybutane; b. 1-propoxypropane; c. 2-ethoxypentane

– O – CH3 – O – CH3

CH3 – CH2 – CH2 – CH – CH2 – CH2 – CH2 – CH2 – CH3

O

CH2 – CH3 CH3 – CH – CH2 – CH3

O

CH3 – CH – CH3

d. e.

f. g.

4. a. 2-butanone; b. 3-methylbutanal; c. 2,3-dimethylpentanal; d. 5,6-dimethyl-3-heptanone;e. 7-methyl-4-octanone

5. a. 4-ethylhexanoic acid; b. hexanoic acid; c. 3-ethylhexanoic acid; d. 4,7-dimethyloctanoic acid;e. 3-methylbutanoic acid; f. 4-n-butyl-4-methyloctanoic acid (The "-n-" is optional.)

6. a. n-propyl butanoate (the n is optional here and in parts c, e, and f); b. methyl pentanoatec. n-butyl propanoate; d. isopropyl ethanoate; e. n-propyl pentanoate; f. n-pentyl methanoate

7. a. ethyldimethylamine; b. ethylmethylamine; c. 2-amino-4-methylheptane;d. methylpentylamine; e. triethylamine; f. 1-amino-6-methyloctane;g. isopropylamine (or 2-aminopropane); h. cyclobutylamine (or aminocylcobutane)

8. a. methanamide; b. pentanamide; c. 4-ethylhexanamide; d. 3,3-dimethylbutanamidee. 5-ethyl-3-methylheptanamide; f. 3,3,5-trimethylhexanamide

26–19 ©1997, A.J. Girondi

9. a. 2,3-dichloropentane; b. difluoromethane; c. 4-bromo-2-fluoro-3-iodohexane;d. 3-bromo-1-butene; e. 1-bromoheptane; f. dichlorodifluoromethane

F – C – F

F

F

Cl – C – C – H

Cl

Cl H

H

Cl

F

F

I

CH C – CH – CH – CH2 – CH – CH3

Br

Br

CH3

ClCl

Cl

10. a. b. c. d.

e. f. g.

11. a. OK; b. 2-methyl-2-butanol; c. 4-bromo-2,2,3-trimethylheptane; d. 3-methyl-3-hexanol;e. 2-chloro-3,3-dimethyl-2-butanol; f. 1-butanol

Br Br

Br

CH3 – CH – CH – CH3

Cl

Cl

CH3 – CH2 – CH – CH – CH2 – OH

CH3

CH2 – CH3

CH3 – CH2 – CH2 – O – CH2 – CH3 CO

HCH3 – C – CH2 –

CH3

CH3

CH3 – CH – C – CH2 – CH2 – CH2 – CH3

O

O – CH3

CH3 – CH2 – C – CH2 – CH3

O

CO

HCH3 – CH2 – CH – CH – CH2 –

CH2 – CH3

CH2 – CH3

CO

HCH3 – CH2 – CH – CH2 – CH –

F

F

12. a. b. c.

d.

OH

I

CH – CH3

CH3

e. f.

g. h.

i. j.

12. k. CH3–CH2 –CH COH

OOH

CO – CH2 – CH3

O

CH3

CO – CH2 – CH2 – CH3

O

CH3 – (CH2)6 CH3 – CH2 – CH – CH – CH2 – CH2 – CH3

Cl

Br

l.

m. n.

26–20 ©1997, A.J. Girondi

C

NH2

O

CH3 – CH2 H – N – CH3

CH2 – CH3

H – C – N – CH3

CH3

CH3

H3C

C

NH2

O

CH3 – CH – CH2

CH3

CH3 – CH – CH2 – C – CH3

Cl O

CH3 – CH – CH – CH COH

O

I I

I

12. o. p. q.

r. s.

t.

13. a. aminoethane; b. 2-aminopropane

26–21 ©1997, A.J. Girondi