A. Perjessy et al., INFRARED-SPECTRA AND THEORETICAL-STUDY OF THE CONFORMATIONS OF SUBSTITUTED BENZOYLKETENE-S,S-ACETALS, Monatshefte fuer Chemie, 125(12), 1994, pp. 1389-1396
The C=O stretching frequencies of substituted benzoylketene-S,S-dimeth
ylacetals (1a-1o) and benzoylketene-S,S-ethyleneacetals (2a-2m) were m
easured in CHCl3 and CCl4 and correlated with the Hammett substituent
constants. The correlations were split into two different and well sep
arated lines for compounds containing electron donor and electron acce
ptor substituents, which were assigned to s-trans and s-cis quasiplana
r conformations. The correlations of carbonyl stretching frequencies w
ith C=O bond orders and oxygen atom charge densities calculated using
the semiempirical AM1 method reveal similar results consistent with as
signments of structures 1 and 2 to two quasiplanar conformations. The
preparation of some new benzoylketene-S,S-acetals is reported as well.