Abstract:

The preparation of heteropolytungstoborate, a green and highly active catalyst for the synthesis of limonene-
1,2-epoxide, by chemical reaction was optimized in order to obtain increased yield of limonene-1,2-epoxide. The effects
of molar ratio of dilute sulphuric acid to sodium tungstate, molar ratio of sodium tungstate to boric acid, molar ratio of
cetyl trimethyl ammonium chloride (CTMA) to sodium tungstate, reaction temperature and time on the yield of limonene-
1,2-epoxide were investigated by one-factor-at-a-time method. Further, all process parameters except reaction time were
optimized using an orthogonal array design. Results showed that when the synthesis of limonene-1,2-epoxide was carried out
using the heteropolytungstoborate catalyst obtained after 1 h reaction at 80 ℃ with a molar ratio of dilute sulphuric acid to
sodium tungstate, sodium tungstate to boric acid, and CTMA to sodium tungstate of 1.5:1, 3:1, and 1:3 respectively, the yield
of product was as high as 4.351 6%. These results suggested that the optimized process produced a catalyst that allowed a
remarkable increase in product yield in the synthesis of limonene-1,2-epoxide.

Key words: heteropolytungstoborate, limonene, limonene-1,2-epoxide, catalytic oxidation