The AlCl3 catalyzed reaction of 1,1-d2-1-chloropropane with benzene was carried out in excess benzene at about 5° or in 1,2,4-trichlorobenzene as solvent at 0°. The products, n-propylbenzene and isopropylbenzene, were examined by nuclear magnetic resonance and mass spectrometry. The results indicated only very minor amounts of isotope position scrambling in the propyl side chain, suggesting no major involvement of protonated cyclopropane intermediates in the reaction. The mass spectral data, however, demonstrated that the products are quite labile in the reaction medium, with extensive intermolecular hydride and deuteride transfers taking place.