STEREOCHEMICAL CONSEQUENCES OF RECOIL HALOGEN ATOM SUBSTITUTION .6. CL-38 FOR-X (X = CL,F) REACTIONS IN GASEOUS, LIQUID AND SOLID DIASTEREOMERIC DIHALOALKANES

The substitution reactions of hot Cl-38-for-X (X = F,Cl) produced by r adiative neutron capture were studied in (2S,3R)-dl-and (2S,3S)-dl-chl orofluorobutane (CFB's), (2S,3R)-meso- and (2S,3S)-dl-dichlorobutane ( DCB's), (2S,3S)-dl-2-chlorofluoropentane and (2S,3S)-dl-3-chlorofluoro pentane (CFP's) and in (3S,4R)-dl- and (3S,4S)-dl-chlorofluorohexane ( CFH's). Experiments were carried out in the gas, neat liquid, in solut ions of n-hexane and acetonitrile, and in the solid phases. Both Cl-38 -for-Cl and Cl-38-for-F substitutions at the chiral carbons occur main ly by substitutions with retention of configuration but with significa nt yields for the inversion of configuration products for gas, liquid and solid phase systems. A test for conformational effects by comparin g free space or accessibility of each chiral center for substitution b y attack of a hot atom with retention and inversion to experimentally determined values showed no significant correlation. While steric hind rance is an important factor for these substitution reactions, other p arameters such as mass, size, polarizability and electronegativity, et c. must be considered.