Ring Transformation of γ-Butyrolactone into γ-Thiobutyrolactone over Alkaline Cation Exchanged Zeolites

Abstract

Abstract The reaction of γ-butyrolactone and hydrogen sulfide to give γ-thiobutyrolactone over zeolites was studied. Alkaline cation exchanged zeolites have high catalytic activity for the ring conversion, acidic zeolites very low activity. γ-Thiobutyrolactone was obtained in 99% yield with CsY at 330 °C. There is no decay of catalytic activity with time. The reaction kinetics over LiY, NaY, and CsY are expressed by r=\frack(aLPL)(aHPH)(1+aLPL+aHPL)2, where r is the rate of reaction, PL and PH are the partial pressure of γ-butyrolactone and hydrogen sulfide, respectively, and k, aL, aH are constants. The activation energies for k are 39, 31, and 26 kcal mol−1 with LiY, NaY, and CsY, respectively. Catalytic activity is enhanced by addition of pyridine but almost completely depressed by addition of hydrogen chloride. It is concluded that basic sites play an important role in the ring transformation.