4-[2,4,6-Tris(1-methylethyl)benzoyl]benzoic Acid (S)-(-)-Proline

The title compound, C₂₃H₂₈O₃.C₅H₉NO₂, is a 1:1 complex of the benzoic acid derivative and the (S)-proline zwitterion, with two formula units in the asymmetric unit (with pseudo-symmetry relationships between the separate components). The ketone carbonyl group in each benzoic acid molecule deviates slightly from a position normal to the plane of the triisopropylphenyl ring; the deviations (of about 16°) are in opposite senses in the two molecules, so that the molecules have opposite conformational chiralities, leading to a nearly racemic photoproduct on solid-state photolysis.

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