The photoinitiated isomerization and addition reactions of liquid 2-butenes in the presence of hydrogen sulfide

Abstract

The near ultraviolet photolysis (λ > 280 nm) of liquid cis-2-butene in the presence of hydrogen sulfide was shown to result in isomerization and addition reactions. The former was monitored by the formation of trans-2-butene as a function of time and hydrogen sulfide concentration. The latter was observed by the presence of s-butyl mercaptan and di-s-butyl sulfide as products. The total amount of addition products as well as the relative amounts of mercaptan and sulfide were determined as a function of time. Using the foregoing information the extent of the isomerization reaction was shown to be greater than that of the addition reaction during the course of the irradiation at a concentration ratio of H2S/cis-2-butene equal to 0.15.It was also shown that hydrogen sulfide was a more effective sensitizer than s-butyl mercaptan and di-s-butyl sulfide but less effective than di-s-butyl disulfide in the isomerization of liquid cis-2-butene. The extent of isomerization and addition reactions were shown to be greater starting with cis-2-butene than with trans-2-butene in the presence of hydrogen sulfide.