Crystal structure of 2,2-diphenylethyl 2,4,6-trimethylphenyl ketone: Kohler's ketone. Mechanism of stereospecific enolization reaction with grignard reagents

The title compound crystallizes in the monoclinic space group P2₁/n with a = 10.875(2), b = 6.039(5), c- 29.015(8)A, and β = 91.29(2). The observed density for Z = 4 la 1.14(1) Mgm^-3 (D_c - 1.155 Mgm^-3). The reliability factors for 1127 unique reflections are R - 0.066 and R_w = 0.064. The dihedral angle between the mesityl ring and the carbonyl to α- carbon plane is 114.4° in contrast to an angle of 89.9° reported earlier for a substituted t-butyl mesityl ketone. A mechanism is proposed for the formation of an E-magnesium enolate from the reaction of Kohler's ketone with Grignard reagents.