ORGANIC COMPOUNDS

1.17

If there is a choice between components of the same size containing

the same number and kind

of heteroatoms, choose as the base component that one with the lower numbers for the heteroatoms

before fusion. When a fusion position is occupied by a heteroatom, the

names of the

component

rings to be fused are selected to contain the heteroatom.

1.1.2.1

Substitutive Nomenclature.

The first step is to determine the kind of characteristic (func-

tional) group for use as the principal group of the parent compound. A characteristic group is a

recognized combination of atoms that confers characteristic chemical properties on the molecule in

which it occurs. Carbon-to-carbon unsaturation and heteroatoms in rings are considered nonfunc-

tional

for nomenclature purposes.

Substitution

means the replacement

of one or more hydrogen atoms in a given compound by

to which it is attached; the latter is denoted the parent compound

(or parent

group if a radical).

In Table 1.7 are listed the general classes of compounds in

descending

order of

preference

for

citation as suffixes, that is, as the parent or characteristic compound. When oxygen

is replaced

by

Structure I

Structure II

1.18

SECTION 1

earliest in Table 1.7, (b) the maximum number of

double and triple bonds considered together,

(c) the maximum length of the chain, and (d) the maximum number of double bonds. Additional

criteria, if needed for complicated compounds, are given in the IUPAC nomenclature rules.

2. If the characteristic group occurs only in a chain

that carries a cyclic substituent, the compound

is named as an aliphatic compound into which the

cyclic component is substituted; a radical

prefix is used to denote the cyclic component. This

chain need not be the longest chain.

TABLE 1.7

Characteristic Groups for Substitutive Nomenclature

Listed in order of decreasing priority for citation as principal group or parent name.

Class

Formula*

Prefix

Suffix

1.

Cations:

-onio-

-onium

H4N

Ammonio-

-ammonium

H3O

Oxonio-

-oxonium

H3S

Sulfonio-

-sulfonium

H3Se

Selenonio-

-selenonium

H2Cl

Chloronio-

-chloronium

H2Br

Bromonio-

-bromonium

2.

Acids:

H2I

Iodonio-

-iodonium

Carboxylic

9COOH

Carboxy-

-

carboxylic acid

9(C)OOH

-oic acid

9C( "O)OOH

-peroxy···carboxylic

acid

9(C "O)OOH

-peroxy···oic acid

Sulfonic

9SO

3H

Sulfo-

-sulfonic acid

Sulfinic

9SO

2H

Sulfino-

-sulfinic acid

Sulfenic

9SOH

Sulfeno-

-sulfenic acid

Salts

9COOM

Metal···carboxylate

9(C)OOM

Metal···oate

9SO

3M

Metal···sulfonate

9SO

2M

Metal···sulfinate

9SOM

Metal···sulfenate

3.

Derivatives of

acids:

Anhydrides

9C( "O)OC( "O)

9

-carboxylic anhydride

9(C "O)O(C "O)

9

-oic anhydride

Esters

9COOR

R-oxycarbonyl-

R···carboxylate

9C(OOR)

R···oate

Acid halides

9CO 9halogen

Haloformyl

-carbonyl halide

Amides

9CO 9NH 2

Carbamoyl-

-carboxamide

(C)O

9NH 2

-amide

1.20

SECTION 1

which (a)

carries the largest number of the principal group or, failing to reach a decision, (b) is

the senior

ring system.

in

which the principal group occurs in largest number. If the numbers are the same, that portion

is

chosen which is considered to be the most important or is the senior ring system.

as prefixes, (m) the lowest-numbered locant

for substituents named as prefixes, hydro prefixes,

-ene, and -yne, all considered together in one series in ascending numerical order independent of

their nature, and (n) the lowest-numbered locant for the substituent named as prefix which is cited

first in the name.

Numbering of Compounds.

If the rules for aliphatic chains and ring systems leave a choice, the

starting point and direction of numbering of a compound are chosen so as to give lowest-numbered

locants to these structural factors, if present,

considered successively in the order listed below until

4.

The

lowest-numbered locant for substituents named as prefixes, hydro prefixes, -ene, and -yne,

all

considered together in one series in ascending numerical order

5.

The

lowest locant for that substituent named as prefix which is cited first in the name

For cyclic radicals, indicated hydrogen and thereafter the point of attachment (free valency) have

priority

for the lowest available number.

Prefixes and Affixes.

Prefixes are arranged alphabetically and placed before the parent name;

multiplying affixes, if necessary, are inserted and

do not

alter the alphabetical order already attained.

The parent name includes any syllables denoting a change of ring member or relating to the structure

of

a carbon chain. Nondetachable parts

of parent names

include