Isomerization of a-Pinene, Limonene, aa-Terpinene and Terpinolene on Sulfated Zirconia

NORA A. COMELLIA, ESTHER N. PONZI, MARTA I. PONZIA

Journal American Oil Chemical Society

Lugar: Estados Unidos; Año: 2005 vol. 82 p. 532 - 535

Transformations of a-pinene, limonene, terpinolene, and a-terpinene were studied in liquid phase on sulfated zirconia having 15% H2SO4, with the aim to identify the pathway of a-pinene isomerization. The principal products obtained in a-pinene isomerization are camphene, tricyclene, limonene, and terpinolene; the concentration maxim observed at 120°C  and 180 min are 53, 6.1, 7.7, and 3.0%, respectively. The principal products formed in the limonene transformation after 20-min reaction time are terpinolene, a-terpinene, and g-terpinene; then the concentration of these products decreases. The terpinolene reaction yields principally m-cymenene, whereas the a-terpinene transformation produces p-cymene. Studies of the initial rates of transformation of terpenes indicate a very high rate for a-pinene, intermediate for limonene and a-terpinene, and very low for terpinolene. The scheme proposed to interpret the results of the a-pinene isomerization reaction on sulfated zirconia is in agreement with reaction schemes proposed by A. Allahverdiev et al.