Abstract: The copper sulfate-loaded on silica gel was used as a catalytic agent for the dehydration of nopol to prepare nopadiene. Major factors influencing the reaction, such as the composition of the copper sulfate-loaded silica-gel, dosage of the dehydrating agent to nopol, reaction time and amount of water-carrying solvent, were investigated and optimized in detail. Under the optimum reaction conditions, i.e the mass ratio of silica gel to copper sulfate 4:1, the molar ratio of copper sulfate in the dehydrating agent to nopol 1:4, reaction time 4h, and using toluene as a water-carrying solvent (14 times to nopol in mass), nopadiene was prepared at a yield of 83.0% with a GC purity of 91.0%. The structure of nopadiene was characterized and identified by FT-IR, GC-MS and ¹HNMR. The reaction mechanism was also proposed.

Key words: nopadiene, nopol, copper-sulfate-loaded silica-gel