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Organic-Nomenclature


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NOMENCLATURE IN ORGANIC CHEMISTRY Contents

A. Halogen and Nitro- Substituted Aromatics

24

B. Carboxylic Acids and Derivatives

24

C. Phenols and Thiophenols

25

D. Aldehydes and Ketones

26

1. INTRODUCTION

3

E. Sulfonic acids and Sulfonic Acid Derivatives

27

2. HYDROCARBONS

3

F. Aromatic Amines

28

(i)

(ii)

G. Diazonium Salts

29

Alkanes

3

A. Unbranched Chains

3

B. Unbranched chains

4

A. Alkyl Halides

29

Alkenes

5

B. Alcohols

29

A. One double bond

5

C. Ketones

30

6. RADICOFUNCTIONAL NAMING

29

B. More than one double bond

5

D. Nitriles (or Cyanides)

30

C. E/Z Isomers in Alkenes

6

E. Grignard Reagents

30

(iii)

Alkynes

8

(iv)

Combined Alkenes and Alkynes

8

(v)

Cyclic Hydrocarbons

9

3. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS

10

4. COMPOUNDS WITH FUNCTIONAL GROUPS NAMED AS SUFFIXES

12

(i)

(ii)

General Naming Scheme

12

A.

Choosing the Principal Chain

13

B.

Naming the Principal Chain

13

C. Numbering the Principal Chain

13

Naming Various Classes of Organic Compounds

14

A. Ethers and Thioethers

14

B.

14

Alcohols and Thiols

C. Acids, Salts of Acids and Acid Anhydrides

15

D. Esters

17

E. Acid Halides

18

F.

18

Amides

G. Nitriles

19

H. Aldehydes

19

I.

21

Ketones

J. Amines and Ammonium Salts 5. AROMATIC COMPOUNDS

22

Revised and updated

23

Professor L D Field May 2004

(i)

General Notes

23

(ii)

Aromatic Hydrocarbons

23

(iii)

Substituted Aromatic Hydrocarbons

24

1

2

B.

NOMENCLATURE IN ORGANIC CHEMISTRY 1.

INTRODUCTION

It is important that organic compounds are corrrectly and unambiguously named so that there can be absolutely no confusion about what compounds are actually being reported or described. There have been many conventions for naming organic compounds - some have had limit scope or become embedded in common usage and some have persisted over time The International Union of Pure and Applied Chemistry (I.U.P.A.C.) periodically reviews naming practice, attempting to standardise nomenclature. The following guidelines for organic nomenclature are based on the definitive rules published by I.U.P.A.C.1 (the International Union of Pure and Applied Chemistry).

2.

HYDROCARBONS

(i)

The Alkanes (CnH2n+2)

A.

Unbranched Chains

Branched Chains

The following steps are taken in naming an alkane with a branched chain: (a)

Find the longest continuous carbon chain and select the appropriate alkane name from Table 1. (Side chains are not included in the carbon count.)

(b)

Name all of the side chains (carbon chains attached to the longest chain) and list them in alphabetical order. Ignore multiplicative prefixes such as “di-“ (2), “tri-“ (3), "tetra-" (4) etc. Also ignore "sec-" and "tert-" but not "iso".

(c)

Number the longest chain so that substituents have the lowest possible numbers and insert location numbers before each of the side chain names.

Special Note: The following groups have the special names indicated:

CH 3

CH3 isopropyl

CH

CH CH2 CH3

CH3

The first four (n=1-4) unbranched chain saturated hydrocarbons are called methane, ethane, propane and butane. After this, there is a numerical term (of Greek origin) followed by the ending "-ane". The first twelve members are given in Table 1.

CH 3

secondary-butyl

CH

sec-butyl

Table 1.

CH 3

The names of the first 12 linear alkanes

n

Name

Molecular formula

1

methane

CH4

CH4

Constitutional formula

2

ethane

C2H6

CH3CH3

3

propane

C3H8

CH3CH2CH3

4

butane

C4H10

CH3CH2CH2CH3

5

pentane

C5H12

CH3CH2CH2CH2CH3

6

hexane

C6H14

CH3CH2CH2CH2CH2CH3

7

heptane

C7H16

CH3CH2CH2CH2CH2CH2CH3

8

octane

C8H18

CH3CH2CH2CH2CH2CH2CH2CH3

tert-butyl t-butyl

3-methylpentane

CH3 CH3 CH

CH2 CH CH CH2 CH3

CH3

C9H20

CH3CH2CH2CH2CH2CH2CH2CH2CH3

decane

C10H22

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

11

undecane

C11H24

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3

12

dodecane

C12H26

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3

2,4,5-trimethylheptane (not 3,4,6-)

CH3 CH3 CH3

CH3 CH2

CH2 CH

CH2 CH CH3

CH CH3

CH3

4-isopropyl-2,2-dimethylheptane

CH3

4-ethyl-5-methyloctane

CH3 CH2

The group derived from one of these alkanes by removal of a terminal (end) hydrogen is called an alkyl group. The group name is found by removing "ane" from the alkane name and adding "yl".

CH3 CH2 CH2 CH CH CH2 CH2

CH3

(not 5-ethyl-4-methyloctane)

CH3

butane

CH3-CH2-CH2-CH2-

CH3

CH3 CH2 CH CH2 CH3

nonane

becomes

CH3 C

s-butyl

tertiary-butyl

Examples

9

CH3-CH2-CH2-CH3

CH3

CH3

10

Example:

isobutyl

butyl

Note: The free valence must be on the terminal carbon. 1

I.U.P.A.C. Nomenclature for Organic Chemistry, Sections A, B and C (combined edition), Butterworths Scientific Publications, London, 1971.

3

4

The following compounds have special names: CH3 CH

CH3

CH3 CH3 CH

isobutane

CH3 CH CH

isopentane

CH3 C CH CH

4,4-dimethyl-2-pentene

CH3

CH3

CH3 C

2-butene

CH3

CH3

CH2CH3

CH3

CH3

propene

CH3 CH CH2

Special Note

neopentane

CH3

Branched side chains are named by renumbering the alkyl group giving the carbon with the free valence (i.e. point of attachment to the main chain) the number 1 and giving substituents the appropriate number in the usual way.

B.

Examples CH3CH2 CH

has the special name “ethylene”.

CH2 CH2

CH3

More than one double bond (a)

Find and name the longest carbon chain containing the maximum number of double bonds.

(b)

Change the "ane" of the alkane name to:

CH2

2-methylbutyl group

CH3

CH3 CH CH CH2 CH CH3

1,3,4-trimethylpentyl group

"adiene"

2 double bonds

"atriene"

3 double bonds

"atetraene"

4 double bonds etc.

(c)

Number the chain so as to give the double bonds the lowest possible numbers.

(d)

Name the alkyl side chains in the usual way.

CH3 CH3 (note position of numbers and punctuation)

Examples The following example gives the name of an alkane having a branched side chain:

CH2 CH

CH3 CH CH C CH CH

CH2 CH3

CH3 CH2 CH2 CH CH2 CH CH2 CH2 CH2 CH3 CH2

CH3 CH2 CH2 CH2

CH2 CH3

The Alkenes (CnH2n)

A.

One double bond (a)

Find and name the longest carbon chain containing the double bond.

(b)

Change the “ane" of the alkane name to “ene".

(c)

Number the carbon chain giving the double bond the lowest possible location number.

(d)

Name side chains in the usual way.

Examples

CH3

CH2 4-butyl-2-methyl-1,3,5-heptatriene

Special Note

4-ethyl-6-(2-methylbutyl)undecane

(ii)

1,3-butadiene

CH2 CH CH CH2

CH3

CH2 C CH2

C.

has the special name “allene”.

E/Z Isomers in Alkenes

In the past, the terms cis and trans have been used to differentiate the isomers; cis to indicate the isomer in which the substituents are on the same side of the double bond, trans when they are on opposite sides. This nomenclature is still used in some older texts, however, the approved nomenclature for alkene stereoisomers involves the prefixes Z- or E-. There are two substituents attached to each of the carbon atoms which form a C=C. The carbon atoms at either end of the C=C are considered separately and at each end, the two attached substituents are ranked according to a simple set of priority rules (or sequence rules). The priority of the two groups attached to each carbon atom of the C=C is based initially on the atomic number of the atom at the point of attachment. For example, a chlorine

(note position of numbers and punctuation)

5

6

substituent would have a higher priority than a CH3- which in turn would have a higher priority than a H-.

CH3

When the C=C is considered as a whole, if the groups with the highest priorities are on the same side of the double bond then the name of the alkene is prefixed with a Z (from the German 'zusammen' meaning 'together'). If they are on opposite sides then the prefix is E (from 'entgegen' meaning 'opposite'). high priority

high priority

high priority

A C

B

priority X > Y

Y

low priority

C

B

low priority

CH3

E-3-chloro-2-methyl-2-penten-1-ol

CH2OH

(note that –Cl has higher priority than –CH3 and -CH2OH has higher priority than -CH3)

C C CH3

priority X < Y

Y

low priority

Z- alkene

Cl

X C

priority A > B

(note that –CH2CH3 has greater priority than – CH3)

CH2CH3

H

low priority

A

X C

priority A > B

E-3-methyl-2-pentene

CH3 C C

(iii)

high priority

The Alkynes (CnH2n-2)

These are named in identical fashion to alkenes except that "ene" in the alkene name is replaced by:

E- alkene

Priority Rules Each of the atoms attached directly to the C atom of a C=C is assigned a priority based on its atomic number: the higher the atomic number, the higher the priority. In terms of priority, if there is a hydrogen attached to one carbon of the C=C, it must always have the lowest priority. Groups which have an oxygen atom attached directly to the C=C (eg. -OH, -OCH3) have higher priority than groups which have a nitrogen atom attached directly to the C=C atom (eg. –NH2, -N(CH3)2) and so on. -I > -Br > -Cl > -OH > -NH2 > -CH3 > -H

"yne"

1 triple bond

"adiyne"

2 triple bonds

"atriyne"

3 triple bonds etc.

(note position of numbers and punctuation)

Example

CH3

C

CH2

2-pentyne

CH3

Special Note has the special name “acetylene”.

H C C H

If two of the groups attached to the same carbon of a C=C begin with the same element (eg. –CH3, -CH2CH3), then look to the next atoms away from the C=C. If the groups at this point are still the same, then move further from the C=C until the point of difference is found (there must be a point of difference somewhere). The group priority is then assigned based on the atomic numbers of the atoms at the point of difference.

C

Salts of Alkynes The salts of hydrocarbon anions are named by adding the ending "-ide" together with a location number. Examples

So for example –CH2Cl has a higher priority than –CH2OH.

CH3

-CH2Br > -CH2Cl > -CH(CH3)2 > -CH2CH3 > -CH3 For the purposes of assigning group priorities, double bonds or multiple bonds are expanded to be an equivalent number of atoms attached by single bonds. So a -CH=CH2 group is considered as equivalent to -CH(-CH2)2.

H3C

C

CH2

-

C C

Li

lithium 1-propyn-1-ide (from propyne)

+

-

+ Na

-C

C

C

sodium 1-butyn-1-ide (from 1-butyne)

Special Note:

Examples

CH3

CH3 C C H

H

H

CH3 C C

(iv) E-2-butene

CH3

Cl

C

C

-

+ Na

+ Na

-

+ Na

C C

are called monosoium acetylide and disodium acetylide respectively

Combined Alkenes and Alkynes

If a compound has double and triple bonds then the longest chain is selected so as to contain the maximum number of double and triple bonds and is named by replacing the "ane" of the corresponding alkane by "en(e)", "adien(e)" etc. followed by "yne", "diyne" etc. The "e" is omitted before a vowel or a "y".

H

CH3

CH3

H Z-2-butene

Z-2-chloro-2-butene

The chain is numbered so as to give the lowest numbers to the double bonds, then triple bonds.

(note –Cl has higher priority than -CH3)

H

7

8

(note positions of numbers and punctuation)

Examples

CH2

CH

C C

CH

C

H

1-buten-3-yne

CH2 CH C CH

CH3

CH2

5-methyl-1,5-heptadien-3-yne

H2C

CH3

C C C CH CH

4-chloro-3-methyl-1-cyclohexene

H C

CH

CH3 H C

Cl C

CH

2-hepten-4,6-diyne

CH2 CH3

Groups derived from alkenes, alkynes or combined hydrocarbons are named by dropping the final "e" and replacing it by "yl". The chain is renumbered to give the carbon with the free valence the number 1 position:

CH3

CH2

(CH2)6 HC

CH2 CH2

CH2

1-cyclohexylheptane (note that the carbon chain has more carbons than the ring)

(note positions of numbers and punctuation)

Examples

CH2

H C C CH CH H C

CH3

2-propynyl group

C CH2

CH CH

H C

2-penten-4-ynyl group

2-butenyl group

CH2

ethynyl group

C

Special Note: The following have special names: vinyl group

CH2 CH CH2 CH H C

(v)

allyl group

CH2

propargyl group

C CH2

Cyclic Hydrocarbons

Compounds with hydrocarbon rings are named by the insertion of "cyclo"- before the name of the hydrocarbon corresponding to the open chain compound containing the same number of carbons. Examples

CH2 H2C

CH2

CH2

CH2

H2C

CH2 CH2

Cyclopropane

Cyclohexane

CH2

9

10

3. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS

3

COMPOUNDS WITH FUNCTIONAL GROUPS NAMED AS SUFFIXES

The halogens (F, Cl, Br, I) and the nitro group (-NO2) are always named as prefixes in the same way as side chains on hydrocarbons. The prefixes are as follows:

(i)

General Naming Scheme

Group

Prefix

F-

fluoro

Cl-

chloro

Br-

bromo

I-

iodo

NO2-

nitro

The name of every organic molecule containing a functional group whose name appears as a suffix may be thought of as made up of four parts:

Numbers Locates the substituents in the molecule

Prefixes

Stem

Substituents in alphabetical order

The name of the pricipal (longest) chain

Suffix Identifes the principal functional group

The Principal Functional Group (PFG) whose suffix name is used is selected from Table 2 The list is in order of decreasing priority. Examples

CH3

Table 2.

Iodomethane

I

CH3 CH CH3 2-chloropropane

Cl

CH3 2-bromo-2-methylpropane

CH3 C CH3 Br CH3 CH2 CH3 CH2 CH CH2 CH2 F

CH2 CH

Cation

ammonio-

-ammonium

Carboxylic acid

-COOH

carboxy-

-oic acid

Sulfonic acid

-SO2OH

sulfo-

-sulfonic acid

Salt of Carboxylic Acid

-COO- M+

carboxylato-

cation name ..-oate

Ester

-COOR

R-oxycarbonyl-

R-…-oate

Acid Halide

C X O

haloformyl-

-oyl halide

Amide

C NH2 O

carbamoyl-

-amide

N

cyano-

-nitrile

C H O

formyl-

-al

oxo-

-one

Aldehyde

Br

CH2 CH2 Cl

4-chloro-1-butene

fluoroform

Cl3C H

chloroform

Br3C H

bromoform

I3C H

Suffix

Nitrile

Special Note: The following have special names: F3C H

Prefix

-NR3+

1-bromo-3-chloropropane

CH2 CH2 CH2 Cl

Formula

3-ethyl-1-fluoropentane nitroethane

CH3 CH2 NO2

Table of Functional Groups (descending order of priority) Class

iodoform

CCl4

carbon tetrachloride

CBr4

carbon tetrabromide

C

Ketone

C O

Alcohol

-OH

hydroxy-

-ol

Thiol

-SH

mercapto-

-thiol

Amine

-NH2

amino-

-amine

Imine

=NH

imino-

-imine

Ether

-OR

R-oxy-

-

Thioether

-SR

R-thio-

-

Wherever "R" appears in the prefix or suffix table then the group name (i.e. alkyl, alkenyl, etc.) for the R group is used.

11

12

A.

Choosing the Principal Chain

The Principal Chain is chosen according to the following rules, applied in order: (a)

The chain must contain the (maximum number of) principal functional group(s); then

(b)

it must contain the maximum number of double and triple bonds; then

(c)

it must be the longest possible carbon chain (the carbons of the -CO2H, -CΞN, -C(=O)H etc. groups are counted when they form part of the principal chain).

B.

Naming Various Classes of Organic Compounds

A.

Ethers and Thioethers

In the naming of ethers as alkyloxy derivatives of alkanes, it is general practice to shorten the names of compounds containing four or less carbons to alkoxy derivatives (i.e., omit the syllable "-yl-°'), e.g., methyloxy becomes methoxy, ethyloxy becomes ethoxy, but pentyloxy (for CH3CH2CH2CH2CH2O-) is correct. An alternative system for naming ethers (or thioethers) is to name the alkyl groups on oxygen (sulfur) and list them in alphabetical order as separate words before the name "ether" (or sulfide).

Naming the Principal Chain

The principal chain is named after the alkane having the same number of carbon atoms, and is modified when unsaturated by the replacement of “ane" by "en(e)", "enyn(e)", "adiene", etc. The final “e” of the name is omitted before "y" or a vowel (e.g. methaneol becomes methanol). C.

(ii)

Examples

CH3 CH2

CH3 CH

The principal chain is numbered according to the following rules, taken in order: (a)

the PFG.'s must be given the lowest possible numbers; then

(b)

the double and triple bonds must be given the lowest possible numbers; then

(c)

the remaining functional groups and substituents must be given the lowest possible numbers.

CH

CH3

C

C

Cl

O

Principal group

Principal chain name plus principal group

C C C

-OH or -SH as the principle functional group

Examples

Modified name ("ane" becomes "en")

5

4

C C C

methanol

CH3

methanethiol

SH

CH3

hexane

2

2-hexanone

1

C C C

OH

3-hexen-2-one

SH

Complete name:

3-chloro

CH3

5-methyl

1,3-propanedithiol

CH3 CH CH CH2 OH

Cl OH

1,4-butanediol

CH2 CH2 CH2

O Prefixes (alphabetical with location number)

2-propanol

CH2 CH2 CH2 CH2

C C C

3

OH

OH

SH 6

CH3 OH

CH3 CH

O

ethyl propyl sulfide or 1-ethylthiopropane

(a)

-one

C C C

CH2 CH3

Alcohols and Thiols

O C C C

isopropyl methyl ether or 2-methoxypropane

B.

CH3

C

Principal chain

diethyl ether or ethoxyethane

CH3

O

CH3 CH2 CH2 S

The following example illustrates the basic approach to naming:

CH2 CH

CH3

CH3

Numbering the Principal Chain

HO

CH2

O

SH

6-hydroxy

2-buten-1-ol cyclohexanethiol

3-chloro-6-hydroxy-5-methyl-3-hexen-2-one

13

14

(b)

Table 3 lists the carboxylic acids that have have special (trivial) names which are preferred to the formal (systematic) names.

-OH or -SH as other than the principle functional group

Examples

CH2 CH2 CH2 CH2

C

OH

O

CH3 CH2 CH CH CH

C

OH

O

Table 3.

H

Special Names of Common Carboxylic Acids Formula

5-hydroxypentanal

H C

OH

CH3 C

OH

CH3 CH2 C

acetic acid

ethanoic acid

OH

propionic acid

propanoic acid

butyric acid

butanoic acid

oxalic acid

ethanedioc acid

malonic acid

propanedioic acid

succinic acid

butanedioic acid

fumaric acid

E-butenedioic acid

maleic acid

Z-butenedioic acid

lactic acid

2-hydroxypropionic acid

O

Alcohol and Thiol Salts The salts of alcohols and thiols are most simply named by adding "-ate" after the "-ol" of the name. Alternatively, the alcoholates may be named as alkyloxides (dropping the "yl" syllable for the first four members as in ether naming). Examples

CH3 CH2 CH2 C

CH3 CH2 CH2 CH2 CH2

O- K+

potassium pentyloxide or potassium pentanolate

Acids, Salts of Acids and Acid Anhydrides

Carboxylic acids are named by identifying the longest carbon chain containing the carboxylic acid functional group and using this carbon chain as the stem for the carboxylic acid name. The ending "-anoic acid" is added to the stem to indicate that the compound is a carboxylic acid.

OH

O HO C

C

O

O

sodium methoxide or sodium methanolate

CH3 O- Na+

C.

methanoic acid

O

3-mercapto-1-propanol

SH

Systematic Name

formic acid

O

4-hydroxy-2-hexenoic acid

CH2 CH2 CH2 OH

OH

Trivial Name

OH

HO C

CH2 C

O

O

OH

HO C CH2 CH2 C O

OH

O

H

COOH

Examples

CH3 CH2 CH2 CH2 CH2

C OH O

CH3 CH2 CH CH CH3 Br

CH2 CH

CH CH2 COOH

hexanoic acid

CH3

H

H

H

HOOC

C OH O

HOOC

2-bromo-3-methylpentanoic acid

COOH

CH3 CH C

OH

OH O 2-ethyl-3-butenoic acid The stem name formed by removal of "-ic" from the trivial name is also used in naming other acid derivatives and aldehydes.

15

16

Acid anhydrides are named when symmetrical by replacement of the word "acid" by anhydride. When unsymmetrical, the two acid groups are named as separate words in alphabetical order and the word anhydride is added.

E.

Acid Halides

Acid halides are maned by replacing the "-ic acid" ending of the parent carboxylic acid with "-yl halide”.

Examples

Examples acetic anhydride

CH3 C O C CH3 O O

CH3

CH3 CH2

sodium butyrate F. ammonium acetate

NH4+

CH3 C CH2 CH2 CH2 C O K O CH

+

Amides

Primary amides are named by identifying the carboxylic acid from which the amide is derived and replacing the "-ic acid" or "-oic acid" ending of the parent carboxylic acid name with the ending "-amide". When there are substituents on the N atom, these are named using N-alkyl or N,N-dialkyl as prefixes (note N or N,N are italicised) immediately before the main chain name.

CH3 -

potassium 5,5-dimethylhexanoate

Examples

3

2+

Ca

CH3 calcium formate (or calcium diformate)

(HCO 2-)2

2-methylpentanoyl bromide

C Br O

CH3 CH2 CH2 CH

Examples

CH3 CH2 CH2 C O- Na+ O

propionyl bromide

C Br O

CH3

Acid salts are named by replacicing the “ic” ending of the acid name with “ate”.

CH3 C O O

acetyl chloride

Cl

O acetic butyric anhydride

CH3 CH2 CH2 C O C CH3 O O

-

C

acetamide

C NH2 O

CH3 CH2 CH2 CH2 CH2 CH2 D.

Esters

The alkyl (alkenyl etc.) group on oxygen is named as a separate word and is followed by the acid salt name ("-ic acid" becomes "-ate").

CH3 CH2 CH2

Examples

CH3

H

CH2

C O

CH3 CH CH

O

C O

CH2 CH3

O

ethyl propionate

NH

O

CH3

propyl formate

C

N

O

CH3

CH3 CH CH2 CH2 CH2 CH2 C O

O

CH2 CH2 CH3

NH2

propyl 2-butenoate

CH3

heptanamide

N-methylbutyramide

N,N-dimethylformamide

CH3 H

CH2 CH2 CH3

C

C O

C

N CH2CH3

O

CH2CH2CH3

6-methyl-N-ethyl-Npropylheptanamide

CH3 CH3 CH2 CH2

C O

O

CH CH3

isopropyl butyrate

17

18

G.

Nitriles

Cl

The nitriles formed from acids with trivial names are named by replacing the “ic acid” ending of the parent carboxylic acid with "-onitrile". Otherwise, "-nitrile" is used as a suffix to the stem name of the parent alkane. Examples

CH3 CH2 CH2 CH2 CH2 CH2 CN

CH CH2

C

H

3-nonenal

O

Special Note: the compound

H

2-hydroxy-2-methylpropanenitrile

CN

OH Cl

hydrogen cyanide (not formonitrile)

H CN

C

C

O

O

has the special name glyoxal

H

Special Note: The prefix "formyl" is only used when a functional group of higher priority is present.

2-chloropentanenitrile

CH3 CH2 CH2 CH CN

H C CH2 CH2 CH2 CH2

C

Special Note: The prefix "cyano" is only used when a functional group of higher priority is present.

CH2 COOH

3-cyanopentanoic acid

C O

methyl cyanoacetate

OH

5-formylpentanoic acid

O

O

CH3CH2 CH

5-chlorohexanal

H

heptanenitrile

CH3 CH3 C

C O

CH3 CH2 CH2 CH2 CH2 CH

acetonitrile

CH3 CN

CH3 CH CH2 CH2 CH2

+ N(CH3)3 Br-

H C CH2 CH2 CH2 CH2

(4-formylbutyl)trimethylammonium bromide

O

CN

NC CH2

H.

OCH3

Derivatives of aldehydes and ketones, e.g. oximes or hydrazones are named simply by adding the word oxime etc. after the aldehyde or ketone name. Examples

CH3 CH2 CH2 C H

Aldehydes

N OH

Aldehydes formally derived from acids having a trivial name are named by adding "-aldehyde" to the trivial stem (see Section 3), otherwise the suffix “-al” is used.

CH3 C

Examples

H

C O

CH3

C

NHNH2 acetaldehyde

H

CH3CH2 C

O

CH3 CH2 CH2

CH3

C

H

acetone oxime

N OH

formaldehyde

H

butyraldehyde oxime

CH2CH3

cyclohexanone hydrazone

3-pentanone oxime

NOH

butyraldehyde (or butanal)

O

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I.

Ketones

J.

Ketones are named by adding the suffix "-one" to the stem of the parent carbon chain. Examples butanone

CH3 C CH2 CH3 O

Examples The following examples show this common naming in practice (together with the formal, systematic names in parenthesis):

3-pentanone

CH3 CH2 C CH2 CH3

Amines and Ammonium Salts

The systematic method of naming amines, whereby "-amine" is added to the principal chain name is, in practice, only rarely used and an older method is in common (I.U.P.A.C. accepted) use. Amines are named as derivatives of ammonia. The longest chain attached to the nitrogen atom is named in the usual way for an alkyl group (the carbon attached to the nitrogen is carbon 1). Any other N-substituents are named as N-alkyl, or N,N-dialkyl substituents. The alkyl name for the longest stem is then added to the suffix "amine".

O cyclopentanone

O

CH3 CH CH2 C CH2 CH3 CH3

CH3

NH2

methylamine (methanamine)

CH3

NH

dimethylamine (N-methylmethanamine)

CH3

5-methyl-3-hexanone

CH3

O

CH3 C CH2 CH2

CH2

C

CH3

CH3

O

O H CH3CH2

O

CH2CH3

4-ethylcyclohexanone

C

CH3

CH3 CH2CH3 CH3CH2CH2CH

acetone

C C

1-ethyl-N-methylbutylamine (N-methyl-3-hexanamine)

NH CH3

O

CH3

N-ethyl-N-methylpentylamine (N-ethyl-N-methyl1-pentanamine)

CH3CH2CH2CH2CH2 N

Special Note: the following compounds have special names:

CH3

dimethylamine (N,N-dimethylmethanamine)

CH3 NH

2,6-heptanedione

CH3

biacetyl Imines are best named systematically

O O

Examples Special Note: The prefix "oxo" is used when the ketone is not the principal functional group.

CH3CH CH3CH2CH2CH

Examples

CH3 C CH2 CH2 C H O

NCH2CH3

N-ethyl-1-butanimine

4-oxopentanal

O

CH3CH2 C CH2CH2COOH

ethanimine

NH

Ammonium Salts are named as alkyl derivatives of inorganic ammonium salts. Note that the N- system is not used and the four alkyl groups attaached to N are listed alphabetically.

4-oxohexanoic acid

Examples

O

tetramethylammonium iodide

(CH3)4N+ I-

CH3CH2CH2CH2CH2CH2

+

CH2CH3 N CH3

-

Cl

diethylhexylmethylammonium chloride

CH2CH3

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5

AROMATIC COMPOUNDS

(iii)

Substituted Aromatic Compounds

(i)

General Notes

A.

Halogen and Nitro- Substituted Aromatics

The use of numbers to indicate the position of substituents on aromatic rings is supplemented in the case of disubstituted derivatives of benzene by the terms:

These are named using halo- or nitro- prefixes before the name of the aromatic hydrocarbon in the usual way.

ortho- abbreviated o- indicating 1,2-disubstitution

Examples

meta- abbreviated m- indicating 1,3-disubstitution

Cl

NO2 chlorobenzene

para- abbreviated p- indicating 1,4-disubstitution

nitrobenzene

Examples

Br benzene

Cl

NO2

o-bromochlorobenzene

NO2 p-dinitrobenzene

O2N

Cl NO2

Cl

I

p-chloronitobenzene

m-iodonitrobenzene

B.

NO2

Carboxylic Acids and Derivatives

The following list gives the trivial (usually accepted) names for some of the common aromatic acids and derivatives.

NO2

COOH

(ii)

1-chloro-2,4dinitrobenzene

COOH CH3

benzoic acid

Aromatic Hydrocarbons

o-toluic acid

The following aromatic compounds have the special name and derived group names shown below: 1

COOH

phenyl group

2

6

benzene

(abbreviated –Ph)

OCH3

4

CH3

CH3 toluene

OCH3

tolyl group

OCH3

ethylbenzene 1

NO2

COOH

7

benzyl group (abbreviated -Bz)

O2N

naphthalene

5

2-naphthoic acid

COOH

COOH

(2-naphthyl shown)

3

6

NO2

2,4,6trinitrobenzoic acid

NO2

naphthyl group 2

3,5dibrombenzoic acid

Br

NO2

anisyl group (o-anisyl shown)

CH2

COOH

m-nitrobenzoic acid

COOH

CH2CH3

Br

COOH

(o-tolyl shown)

anisole

8

phthalic acid

COOH

3

5

COOH m-anisic acid

6-nitro-o-toluic acid

Br

6-bromo-2naphthoic acid

CH3

4

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Carboxylic acid Derivatives

When the -OH group is not the principal functional group, "hydroxy" is used in the usual way.

Acid derivatives, esters, anhydrides, amides and nitriles are named in the usual way, replacing "-oic" or "-ic" of the acid name with the appropriate endings.

Example

OH

Examples

OH p-hydroxybenzoic acid

-

p-hydroxybenzonitrile

COCl

+

COO Na

sodium benzoate

m-anisoyl chloride

COOH

(from m-anisic acid)

CN

OCH3 CN benzonitrile

CONH2 Cl

D. o-chlorobenzamide

Aldehydes and Ketones

Aldehydes are named by replacing the "-ic" or "-oic" of the acid name by "aldehyde”. Examples

O

O O

CH3CH2CH2

C

propyl benzoate

O

C

OCH3

C

methyl o-toluate

C

p-chlorophenyl benzoate

C

phthalic anhydride

O

H

o-tolualdehyde

C

H

salicylaldehyde

OH

O C

Phenols and Thiophenols

OH phenol

H

p-hydroxybenzaldehyde

HO

Phenols have an –OH group attached directly to an aromatic ring.

OH

H

O o-nitrobenzaldehyde

NO2

C O

C.

C

CH3 O

C

O

Cl

H

CH3

O

O

O benzaldehyde

Aromatic ketones are named by changing the "ic" or "oic" ending of the acid name corresponding to the acyl group attached to the benzene ring to "-ophenone"

2-naphthol

Examples

O

OH

OH

C

3,4-dibromophenol

m-cresol

CH3

Br

O

CH3

acetophenone

C

CH2CH3

propiophenone

O

Br

C

SH thiophenol (or benzenethiol)

CH2CH2CH3

m-nitrobutyrophenone

NO2

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Aldehydes and ketones in which the carbonyl group is not directly attached to the aromatic ring are named using the corresponding group name for the aromatic system as a prefix.

F.

Aromatic Amines

Special Names

Examples

NH2

CH2CHO

NH2 aniline

m-toluidine

phenylacetaldehyde

CH3

O CH2 C CH2CH3

NH2

1-(m-nitrophenyl)-2-butanone

NH2 p-anisidine

CH3O

NH2

o-phenylene diamine

NO2 E.

The remaining aromatic amines are named as derivatives of these or (in the presence of more important functional groups) as "amino-" derivatives, or as "phenylamines".

Sulfonic Acids and Sulfonic Acid Derivatives

Sulfonic acids are named by adding the suffix "-sulfonic acid".

Examples 2,4,6-tribromoaniline

NH2

Examples

Br

Br

SO3H benzenesulfonic acid

SO3H

o-hydroxybenzenesulfonic acid

Br

p-toluenesulfonic acid

N

diphenylamine

OH SO3H

H CH3

NHCH3 NO2

2,4-dinitro–N-methylaniline

Sulfonic Acid Derivatives. Derivatives of sulfonic acids (esters, amides and sulfonic acid chlorides) are named by analogy with carboxylic acids.

NO2

Examples

SO2OCH3 methyl o-toluenesulfonate

Ammonium Salts

CH3

These are named by changing the "-e" of the special names to “-ium".

SO2NH2

Examples benzenesulfonamide

-

+

NH3 Cl

SO2Cl m-nitrobenzenesulfonyl chloride +

(CH3)2NH Br

-

NO2

anilinium chloride 3-nitro-N,N-dimethylanilium bromide.

NO2

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Acyl Derivatives (Amides)

C.

Simple acyl derivatives are named by adding the trivial acid name stem to "-anilide" etc.

Ketones

CH3

Example

H N

C

CH3CH2

CH3 dimethyl ketone

O

acetanilide

CH3

C O

C

O

C O

CH3

O methyl phenyl ketone

CH3

CH2 CH C CH3

ethyl methyl ketone methyl vinyl ketone

Diazonium Ions (ArN2+)

G.

These are named in an analogous fashion to sulfonic acids; the syllable "-diazonium" is added to the aromatic name.

D.

Nitriles (Cyanides)

CH3CN

Examples

methyl cyanide

CH2CN benzyl cyanide

+

N2

benzenediazonium ion E.

+

N2

Grignard Reagents

CH3CH2MgBr

p-bromobenzenediazonium hydrogen sulfate

Br

6.

-

HSO4

ethyl magnesium bromide

MgCl

phenyl magnesium chloride

RADICOFUNCTIONAL NAMING

An alternate system of naming, which is still very common in many textbooks, consists of naming the alkyl or aryl groups attached to a certain functional group as separate words followed by the functional group name. The alternative naming of ethers and amines is a remnant of this system. The following examples suffice to illustrate the system. A.

Alkyl Halides

CH3

I

(CH3)3CCl

methyl iodide tert-butyl chloride

(CH3)2CHBr

isopropyl bromide

CH2Cl benzyl chloride

B.

Alcohols

CH3OH

methyl alcohol

(CH3)3COH

tert-butyl alcohol

CH2OH benzyl alcohol

Revised and updated Professor L D Field May 2004

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