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Carbon-13 NMR spectral investigations on allenic esters: Rationalization of carbon-13 NMR chemical shifts and relaxation times (T1)

✍ Scribed by R. P. Gandhi; M. P. S. Ishar

Publisher: John Wiley and Sons
Year: 1991
Tongue: English
Weight: 389 KB
Volume: 29
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1260290706

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✦ Synopsis

Abstract

Carbon‐13 NMR chemical shifts (CDCl~3~ and C~6~D~6~ solvents) and relaxation times (T~1~) were determined for carbons in a series of allenic esters [RR~1~CCCHCO~2~ Et; (1) R = R~1~ = H; (2) R = H, R~1~ = CH~3~; (3) R = H, R~1~ = CH~3~CH~2~; (4) R = R~1~ = CH~3~; (5) R = CH~3~, R~1~ = CH~3~CH~2~]. A comparison of the experimental δ^13^C values with those obtained by semi‐empirical additivity relationships revealed the inadequacy of these relationships to explain the obtained results. A rationalization of δ^13^C and relaxation time data is offered, inter alia, in terms of rotameric conformational preferences of the ester function.

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