SELECTIVE ELECTROCHEMICAL REDUCTIONS OF AROMATIC RINGS IN PRESENCE OF OLEFINIC BONDS

It was established that a nonconjugated, terminal, aliphatic olefin was not readily reduced when electrolyzed in a cell containing lithium chloride dissolved in methylamine as electrolyte. Under the same conditions, styrene was reduced quite cleanly to ethylbenzene. Nonconjugated, aromatic olefins (terminal or internal) with the double bond at least two carbon atoms removed from conjugation were reduced selectively to give 2,5-dihydro aromatic olefins as major products. Allylbenzene, depending upon the electrolysis conditions used, was reduced selectively to either n-propylbenzene or 2,5-dihydroallylbenzene. The latter olefin, in contrast to the behavior of other 2,5-dihydro aromatic types, was found to undergo a facile reduction to 2,5-dihydro-n-propylbenzene. When a terminal, aliphatic olefin was reduced in a divided electrochemical cell, appreciable alkane formation occurred accompanied by extensive isomerization of the double bond. A study of the basecatalyzed isomerization of 1-, cis-2-, and cis-4-octene was made. © 1969, American Chemical Society. All rights reserved.