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preface to fifteenth edition

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7.52 SECTION 7<br />

TABLE 7.23<br />

Absorption Frequencies of Carbonyl Bands (Continued)<br />

Groups Band,cm 1 Remarks<br />

Ke<strong>to</strong>nes C O(continued)<br />

o-Amino-aryl or o-hydroxyaryl<br />

ke<strong>to</strong>nes 1655–1635 Low because of intramolecular H bonding.<br />

Other substituents and steric hindrance affect<br />

the position of the band.<br />

Quinones 1690–1660 C"C band is strong and is usually near<br />

1600 cm 1 .<br />

Extended quinones 1655–1635<br />

Tropone 1650 Near 1600 cm 1 when lowered by H bonding<br />

as in tropolones<br />

Carboxylic acids 9CO 2 H<br />

All types 3000–2500 OH stretching; a characteristic group of small<br />

bands due <strong>to</strong> combination bands<br />

Saturated 1725–1700 The monomer is near 1760 cm 1 ,but is rarely<br />

observed. Occasionally both bands,the free<br />

monomer,and the H-bonded dimer can be<br />

seen in solution spectra. Ether solvents<br />

give one band near 1730 cm 1 .<br />

,-Unsaturated 1715–1690<br />

Aryl 1700–1680<br />

-Halo- 1740–1720<br />

Carboxylate ions 9CO <br />

2<br />

Most types 1610–1550<br />

1420–1300<br />

Antisymmetrical and symmetrical stretching,<br />

respectively<br />

Amides CO N<br />

(See also Table 7.49 for<br />

NH stretching and bending.)<br />

Primary 9CONH 2<br />

In solution ca 1690 Amide I; C"O stretching<br />

Solid state ca 1650<br />

In solution ca 1600 Amide II: mostly NH bending<br />

Solid state ca 1640 Amide I is generally more intense than amide<br />

II. (In the solid state,amides I and II may<br />

overlap.)<br />

Secondary 9CONH9<br />

In solution 1700–1670 Amide I<br />

Solid state 1680–1630<br />

In solution 1550–1510 Amide II; found in open-chain amides only<br />

Solid state 1570–1515 Amide I is generally more intense than amide<br />

II.<br />

Tertiary 1670–1630 Since H bonding is absent,solid and solution<br />

spectra are much the same.<br />

Lactams<br />

Six-ring and larger rings ca 1670<br />

Five-ring<br />

Four-ring<br />

ca 1700<br />

ca 1745<br />

Shifted <strong>to</strong> higher frequency when the N a<strong>to</strong>m<br />

is in a bridged system<br />

R9CO9N9C"C<br />

Shifted 15 cm 1 by the additional double<br />

bond<br />

C"C9CO9N<br />

Shifted by up <strong>to</strong> 15 cm 1 by the additional<br />

double bond. This is an unusual effect by<br />

, unsaturation. It is said <strong>to</strong> be due <strong>to</strong> the<br />

inductive effect of the C"C on the wellconjugated<br />

CO9N system,the usual conjugation<br />

effect being less important in such<br />

a system.

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