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Spectroscopic studies on N, N-dimethylamides—IV An NMR total line shape study of substituent effects and medium effects on amide-rotational barriers of N,N-dimethylbenzamides and -cinnamamides

✍ Scribed by K. Spaargaren; P. K. Korver; P. J. Der Van Haak; Th. J. de Boer

Publisher
John Wiley and Sons
Year
1971
Tongue
English
Weight
472 KB
Volume
3
Category
Article
ISSN
0749-1581

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✦ Synopsis

Amide-rotational barriers obtained with a total line shape analysis of a series of parasubstituted N,N-dimethylbenzamides and -cinnamamides are correlated with the result of an H.M.O.

(a ~~1 . 4 )

calculation. There is no difference in the activation parameters at a concentration of 0.25 M and 1 M in CDCl, as a solvent.

Despite the lower solvent polarity of chloroform ( E = 4.7) compared with acetonitrile ( E = 37.5) the rotational barriers in both solvents are about equal, probably due to hydrogen bonding in chloroform.

The amide rotation rate appears to be very sensitive to traces of hydrochloric acid in a non-basic solvent like chloroform.

I N T R O D U C T I O N

FROM the conjugated N,N-dimethylamides, the benzamides have been investigated most thoroughly. Reported values are presented in Tables 1 and2. Very recently, Spassov et a1.

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