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preface to fifteenth edition

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ORGANIC COMPOUNDS 1.23<br />

such is present. Otherwise, lowest-numbered locants are assigned <strong>to</strong> the heteroa<strong>to</strong>ms considered<br />

<strong>to</strong>gether and, if there is a choice, <strong>to</strong> the heteroa<strong>to</strong>ms cited earliest in Table 1.3. An example is<br />

13-Hydroxy-9,12-dioxa-3,6-diazatridecanoic acid<br />

1.1.3 Specific Functional Groups<br />

Characteristic groups will now be treated briefly in order <strong>to</strong> expand the terse outline of substitutive<br />

nomenclature presented in Table 1.7. Alternative nomenclature will be indicated whenever desirable.<br />

1.1.3.1 Acetals and Acylals. Acetals, which contain the group C(OR) 2 , where R may be different,<br />

are named (1) as dialkoxy compounds or (2) by the name of the corresponding aldehyde or<br />

ke<strong>to</strong>ne followed by the name of the hydrocarbon radical(s) followed by the word acetal. For example,<br />

CH 3 9CH(OCH 3 ) 2 is named either (1) 1,1-dimethoxyethane or (2) acetaldehyde dimethyl acetal.<br />

A cyclic acetal in which the two acetal oxygen a<strong>to</strong>ms form part of a ring may be named<br />

(1) as a heterocyclic compound or (2) by use of the prefix methylenedioxy for the group<br />

9O9CH 2 9O9 as a substituent in the remainder of the molecule. For example,<br />

(1) 1,3-Benzo[d]dioxole-5-carboxylic acid<br />

(2) 3,4-Methylenedioxybenzoic acid<br />

Acylals, R 1 R 2 C(OCOR 3 ) 2 , are named as acid esters;<br />

Butylidene acetate<br />

propionate<br />

-Hydroxy ke<strong>to</strong>nes, formerly called acyloins, had been named by changing the ending -ic acid<br />

or -oic acid of the corresponding acid <strong>to</strong> -oin. They are preferably named by substitutive nomenclature;<br />

thus<br />

CH 3 9CH(OH)9CO9CH 3<br />

3-Hydroxy-2-butanone (formerly ace<strong>to</strong>in)<br />

1.1.3.2 Acid Anhydrides. Symmetrical anhydrides of monocarboxylic acids, when unsubstituted,<br />

are named by replacing the word acid by anhydride. Anhydrides of substituted monocarboxylic<br />

acids, if symmetrically substituted, are named by prefixing bis- <strong>to</strong> the name of the acid and replacing<br />

theword acid by anhydride. Mixed anhydrides are named by giving in alphabetical order the first<br />

part of the names of the two acids followed by the word anhydride, e.g., acetic propionic anhydride<br />

or acetic propanoic anhydride. Cyclic anhydrides of polycarboxylic acids, although possessing a

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