PULSE-RADIOLYSIS OF BENZYL-CHLORIDE AND BENZYL-BROMIDE - THE UV-VISIBLE ABSORPTION-SPECTRUM OF THE BENZYL CATION

Pulse radiolysis study of liquid benzyl chloride has been carried out at room temperature. In order to identify transient species that absor b in the UV-vis region, various scavengers were used including oxygen, ethanol, pyrrole, biphenyl, and mesitylene (1,3,5-trimethylbenzene). The spectrum of the benzyl cation was obtained by subtracting the tran sient spectrum of the 0.6 M solutions of ethanol in O-2-saturated benz yl chloride from that for O-2-saturated benzyl chloride. The differenc e spectrum obtained has a strong absorption band at 303 +/- 2 nm and a weak broad band near 500 nm. The analyses of end products formed in t he y radiolysis of benzyl chloride were done in the presence and absen ce of scavengers. The formation of benzyl ethyl ether with a G value o f 0.9 from a 0.6 M solution of ethanol in O-2-saturated benzyl chlorid e was taken as evidence that added ethanol reacts with benzyl cations to give benzyl ethyl ether. Some pulse radiolysis experiments were per formed with benzyl bromide. Transient spectra observed in benzyl bromi de are similar to those observed in benzyl chloride. It is, however, i nferred from the product analysis that the radiolytic mechanisms of be nzyl bromide appreciably differ from those of benzyl chloride.