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preface to fifteenth edition

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SPECTROSCOPY 7.51<br />

TABLE 7.23<br />

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

Groups Band,cm 1 Remarks<br />

Aldehydes 9CHO<br />

(See also Table 7.49 for<br />

C9H.) All values given<br />

below are lowered in liquid-film<br />

or solid-state<br />

spectra by about 10–20<br />

cm 1 . Vapor-phase spectra<br />

have values raised<br />

about 20 cm 1 .<br />

Saturated 1740–1720<br />

Aryl 1715–1695 o-Hydroxy or amino groups shift this value <strong>to</strong><br />

1655–1625 cm 1 because of intramolecular<br />

H bonding.<br />

,-Unsaturated 1705–1680<br />

,,,-Unsaturated 1680–1660<br />

-Ke<strong>to</strong>aldehyde in enol<br />

form 1670–1645 Lowering caused by chelate-type H bonding<br />

Ke<strong>to</strong>nes C O<br />

All values given below<br />

are lowered in liquid-film<br />

or solid-state spectra by<br />

about 10–20 cm 1 . Vapor-phase<br />

spectra have<br />

values raised about 20<br />

cm 1 .<br />

Saturated 1725–1705<br />

Aryl 1700–1680<br />

,-Unsaturated 1685–1665<br />

,,,-Unsaturated and<br />

diaryl 1670–1660<br />

Cyclopropyl 1705–1685<br />

Six-ring ke<strong>to</strong>nes and larger Similar values <strong>to</strong> the<br />

corresponding<br />

open-chain ke<strong>to</strong>nes<br />

Five-ring ke<strong>to</strong>nes 1750–1740 , Unsaturation, ,,, unsaturation,etc.,<br />

have a similar effect on these values as on<br />

those of open-chain ke<strong>to</strong>nes.<br />

Four-ring ke<strong>to</strong>nes ca 1780<br />

-Halo ke<strong>to</strong>nes 1745–1725 Affected by conformation; highest values are<br />

obtained when both halogens are in the<br />

same plane as the C"O.<br />

,-Dihalo ke<strong>to</strong>nes 1765–1745<br />

1,2-Dike<strong>to</strong>nes, syn-transopen<br />

chains 1730–1710 Antisymmetrical stretching frequency of both<br />

C"O’s. The symmetrical stretching is inactive<br />

in the infrared but active in the<br />

Raman.<br />

syn-cis-1,2-Dike<strong>to</strong>nes, sixring<br />

1760 and 1730<br />

syn-cis-1,2-Dike<strong>to</strong>nes, five<br />

ring 1775 and 1760

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