Study On Synthetic Process Of Guaiacol And Vanillin

The preparation process of guaiacol and vanillin was investigated in this dissertation.O-nitrochlorobenzene was used as starting material by methoxylation, liquid-phase hydrogenation, diazotization and hydrolysis to afford guaiacol. In this paper, methoxylation was mainly studied and its catalysis, conditions and mechanism were studied in conventional liquid-liquid phase transfer catalysis systems (L-L PTC systems) and liquid-liquid-liquid phase transfer catalysis systems (L-L-L PTC systems). (1) Tetrabutylammonium bromide (TBTA) showed the best catalytic activity in conventional L-L PTC reaction, the optimal conditions for the methoxylation could be run smoothly at 70℃for 8 h, and the ratio of m(o-nitrochlorobenzene):m(NaOH):m(CH₃OH):m(TBTA) was 1:1.7:1:0.14. Yield of o-nitroanisole as high as 86.4%was obtained. (2) Tetrabutylammonium bromide(TBTA) showed the best catalytic activity in L-L-L PTC reaction. The optimal conditions for the methoxylation could be run smoothly at 75℃for 5 h, the ratio of m(o-nitrochlorobenzene):m(NaOH):m(CH30H):m(TBTA) was 1:2.1:3:1.53, and organic to aqueous volumes chosen was 40:50. Yield of o-nitroanisole as high as 90.5%was obtained. (3) L-L-L PTC was obviously better than conventional L-L PTC. L-L-L PTC increase methoxylation reaction rate, improved production selectivity and enabled recovery and reuse of catalysis.Guaiacol was used as starting material by acetylation, fries rearrangement, oxidation to afford vanillin. In this paper, oxidation was mainly studied. (1) CUSO₄ as catalyst showed the best catalytic activity. The optimal conditions for oxidation could be run smoothly at 195℃and 1.3MPa (air) for 3h, and the ratio of m(acetovanillone):m(NaOH):m(CuSO₄) wasl:4:0.05. Yield of vanillin as high as 89%was obtained. (2) acetovanillone as the waste from industry was used to prepare vanillin, which follows green chemistry requirement and therefore has great developing prospect.