The bromochlorofluoromethane saga.

Abstract

Synthesis of optically active samples of bromochlorofluoromethane (CHFClBr) was performed via fractional crystallisation of the strychnine salts of bromochlorofluoroacetic acid (FClBrCCO2H). The S-(+) (R-(-)) absolute configuration of the acid was established by X-ray crystallography and the S-(+) (R-(-)) absolute configuration of the haloform was determined using Raman Optical Activity (ROA) and molecular modelling of the enantioselective molecular recognition process of CHFClBr by the chiral cryptophane-C. From these stereochemical assignments it was observed that the decarboxylation used to obtain S-(+)- and R-(-)-CHFClBr from respectively S-(+)- and R-(-)-FClBrCCO2H occurred with retention of configuration. Finally, the first parity violation (PV) test on CHFClBr was performed and yielded an upper bound for this small stereophysical effect.