Hydration Of α-Pinene Over Heteropoly Acid Ionic Liquids

Aiming at the insufficiency and the problems of a-pinene catalytic hydration process, regarding environmentally friendly technology of catalysis as the goal, taking the simplicity and the effectiveness of both reaction and separation into account, a variety of ionic liquids which had the structures of ionic liquids and heteropoly organic salts were designed and synthesised, and were used into the hydration of a-pinene. Four kinds of green catalytic processes were developed, and behaved good catalytic effects. The structure of the catalysts which were optimized was characterized by’H NMR and FT-IR, and the acids were investigated by adopting the method of n-butylamine potentiometric titration. Each component of anion and cation was studied to reveal the rule of structure-activity relationship, such as melting point, solubility.In the use of chloroacetic acid which was aided catalyst, the effects of different cations and anions of heteropoly acid ionic liquids were studied in hydration reaction. The results showed that the catalysts with sulfonic group had high acidic strength, although the activity was very high, but these catalysts were not good for hydration reaction, isomerized products accounted for a very large proportion; The low of the acid strength, the activities of the catalysts were low. Heteropoly acid ionic liquid [HPY]4SiW12O40 which acid strength was at about 300 mv had better catalytic effect. The reaction conditions as follows:the a-pinene 8.2 g, n (a-pinene):n (catalyst):n (chloroacetic acid):n (water)= 6:0.1:6:30, reaction time 8 h, reaction temperature 80℃, the conversion of a-pinene was 89.7%, and the selectivity a-terpineol was 54.2%. The catalyst not only showed a good catalytic effect, but at the end of the reaction, it was a three-phase system, the catalyst was at the bottom of the reaction vessel. It did not dissolve in oil and water, so the catalyst almost had no loss, and it could be easily recycled. Thus it could have a good reusable performance.In order to avoid the use of cocatalyst of chloroacetic acid which might lead to environmental problems, polyether type octadecylamine heteropoly ionic liquids which had surface-active action were designed and synthesized, and were used in the hydration of a-pinene in the absence of chloroacetic acid, which was in microemulsion form, oil-water two phase could contact sufficiently, set aside for a long time after the hydration reaction, the microemulsion could demulsify gradually, the catalyst dissolved in water phase and had a good response to the separation performance. The effects on hydration reaction by different degrees of polymerization were studied, it was concluded that, with increasing degrees of polymerization, the conversion of a-pinene was reduced, and the selectivity of a-terpineol first and decreased afterwards. Combining with the conversion, selectivity and system to the difficulty of the demulsification, the best degree of polymerization was 100. The conditions were optimized:reaction temperature 80℃, reaction time 8 h, a-pinene 8.2 g, water 5.4 g, dosage of catalyst 7.6 g, selectivity of a-terpineol was 44.3%, and the conversion of a-pinene was 76.9%. Moreover, the catalyst could be repeated using.In view of the present hydration process of a-pinene, the chloroacetic acid with carboxyl played a decisive role, so carboxyl was introduced in cationic structure of ionic liquids. Using amino acids and phosphotungstic acid as raw materials, a series of amino acids functionalized heteropoly ionic liquids were synthesized. In the absence of chloroacetic acid, the effects of different cations and anions in hydration reaction were studied. [Asp]3PW12O40, [Thr]3PW12O40 and [Ser]3PW12O40 showed good catalytic effects, both the conversion and selectivity were at around 50%. In addition, these kinds of catalysts could dissolve in water, and the system was a two phase reaction, so it was convenient for separation and recycling.With chloroacetic acid, dichloroacetic acid and N-methyl imidazole as raw materials, a series of carboxyl functionalized ionic liquids were synthesized to simulate the function of chloroacetic acid, and used them to catalyze the hydration reaction. Results showed that the carboxyl functionalized ionic liquids of [MIMCH(Cl)COOH]HSO4 which used dichloroacetic acid as material had relatively good catalytic effects, and by changing the dosage of catalyst, the catalytic effects were promoted, When the dosage of [MIMCH(Cl)COOH]HSO4 was 8.2 g, the conversion of a-pinene was 80.4%, the selectivity of a-terpineol was 34.7%, it showed better catalytic effects. The ionic liquids were stability in the water, and could dissolve in water. It was a two phase reaction with simple post-processing. A new environmentally friendly method for making a-terpineol by α-pinene was developed.