Collect. Czech. Chem. Commun. 1988, 53, 1260-1267

Conformations of molecules bearing two carbonyl groups on adjacent atoms

Otto Exnera, Václav Jehličkab and Bernard Tinantc

a Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6, Czechoslovakia
b Department of Physical Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czechoslovakia
c Laboratory of Physical Chemistry and Crystallography, University of Louvain, B-1348 Louvain-la-Neuve, Belgium


Conformation of α-acyloxyketones IIIa-IIIc was determined from their dipole moments in benzene solution. Around the C-O bond the ap conformation prevails over sc, around the C-C bond several conformations are present and those with a larger distance between the two carbonyl oxygens are preferred. The conformation in thus quite different than in crystal. Similarities of the crystal conformations of III to I or II are due mainly to crystal packing forces, while the interaction of the two carbonyl oxygen atoms is of little importance.