4,4′-Dimethylchalcone is an achiral molecule that crystallizes from ethyl acetate in the chiral space group P2 1 2 1 2 1 . Herein we report the effect of beta radiolysis and circularly and linearly polarized light on the crystallization of 4,4′-dimethylchalcone from ethyl acetate. Exposure of the evaporating solution to energetic beta particles from a Sr-90 source generated a random distribution of (+) and (-) crystals. Irradiation of the evaporating solution by intense right-or left-circularly polarized light (1064 nm) from a Nd:YAG laser afforded results that were comparable to the results of the beta radiolysis experiments. Linearly polarized light (LPL), on the other hand, had a profound influence on the distribution of crystals, yielding in this instance a large bifurcation of (+) and (-) crystals. A likely cause of this outcome may be due to the optical Kerr effect. The anisotropic polarizability of the chalcone molecule causes a preferential alignment in the direction of the E field when using LPL. This molecular alignment results in a sizable enantiomeric excess. Circularly polarized light does not produce the alignment of the chalcone and thus has no effect on the asymmetric induction. This alignment offers an opportunity for chirally autocatalytic secondary nucleation to occur, which is then able to amplify small initial asymmetry in the number of (+) and (-) crystals. The chirality of the chalcone crystals was determined via their reaction in water with pyridinium tribromide to yield the chiral compound erythro 1,2-dibromo-4,4′-dimethylchalcone, thus allowing the chirality of the crystal to be propagated to molecular chirality.

Racemic, optically active, and 2-deuterio-2-iodooctane were photolyzed in mixtures of acetonitrile (AN) and water ranging from 95% to 50% AN by volume. The major products in all cases were 1-, (E)-2-, and (Z)-2-octene. Minor products consisting of 2-, 3-, and 4-octanol and N-2-, N-3-, and N-4-(methylheptyl)acetamide were also formed in all cases. These products arise from the reaction of octyl cations with water and acetonitrile, with water being 4 -5 times more reactive with the cations than acetonitrile. Octane was also formed in small yields, but no meso nor d,l 7, 8-dimethyltetradecane, as was seen in significant amounts in previously reported solvents. The behaviour of the 2-deuterio-2iodooctane demonstrated that a small fraction of the reaction occurred through the 2-octyl carbene. The carbene was found to react with AN but not with water, an unusual result. Analysis of all these data showed that approximately 90% of the reaction occurred via the 2-octyl cation, 2 -4% through the 2-octyl radical, and 4 -6% through the 2-octyl carbene. F, the fraction of the intermediates going to 81 product, was determined by examining the behaviour of optically active 2iodoooctane in 95%, 90%, and 80% AN by volume. F goes up in value as the amount of water in the solvent increases, a result consistent with the photoreaction proceeding largely through ion pairs and free ions.