A Technical Study On Synthesis Of1,2-diols

1,2-diols are an important chemical raw material. Technical study on synthesis of1,2-diols was rarely reported in the literature at home and abroad. The report that terminal olefins (1-hexene and1-octene)、 organic acids (HCOOH) and hydrogen peroxide (H2O2) as the main raw material synthesized1,2-diols was even less. So this paper provide a more systematic technical study for synthesis of1,2-diols, terminal olefins (1-hexene and1-octene), organic acids (HCOOH), hydrogen peroxide (H2O2) as the basic raw material, using phosphotungsticacid quaternary ammonium salts [(C18H37)2N(CH3)2]3[PW4O16] as a reaction-controlled phase transfer catalyst. The main research contents and results about synthesis of1,2-diols are as follows:(1) In allusion to the system of oxidating terminal alkenes, several heteropolyacid quaternary ammonium phase transfer catalysts were prepared, some important reaction conditions during the catalyst preparation were examined such as on the first step of reaction time and reaction temperature. The experimental results show the high yield of heteropolyacid quaternary ammonium phase transfer catalyst under the optimal synthesis conditions:n(H3PO4):n(H2WO4)=1:4, the first step of the reaction time of15min, the reaction temperature of60℃. Meanwhile, the experiments showed that the catalyst for the oxidation terminal alkene synthesis of1,2-diol has better catalytic activity. The structures of the synthesized four catalysts were characterized by FTIR, by comparison of catalytic reactive oxygen species,[(C18H37)2N(CH3)2]3[PW4O16] and [π-C5H5NC16H33]3[PW4O16] have a great catalytic activity.(2) Analytical methods of terminal alkene oxidation reaction and hydrolysis reactions were established. Qualitative analysis method was performed using terminal alkenes oxides directly into the gas chromatography analysis to take online program product composition temperature method, the desired products1,2-diols take constant GC testing. On the basis of the qualitative analysis, the pass yield of target products1,2-diols are accurately calculated. Meantime, the target products were characterized by FTIR and NMR.(3) Optimization of reaction process conditions about preparation of high purity1,2-diols were found. Use single factor experiment were investigated the synthesis of organic peroxy acid, the reaction temperature, the dropping terminal alkene rate, the effect of hydrolysis reaction, the amount of catalyst and cycle times of catalyst and other fators. The experimental results show that the catalyst reveals high catalytic performance with the yield of high purity1,2-diols under the optimal conditions:the organic peroxy acid synthesis reaction at25℃1.5h, the molar ratio of n(1-hexene):n(H2O2):n(HCOOH)=1:1.4:5,1-hexene dropping rate control0.03mol/h, the temperature of the oxidation reaction is controlled25℃, n(catalyst)/n(1-hexene)=1:200, the pH of the hydrolysis reaction is maintained11to12, the hydrolysis reaction at40℃2h, the desired product1,2-hexanediol yield is up to90.4%.1,2-octanediol optimum synthesis conditions of the organic peroxy acid synthesis reaction at25℃1.5h, the molar ratio of n(1-octene):n(H202):n(HCOOH)=1:1.4:5,1-octene dropping rate control0.045mol/h, the temperature of the oxidation reaction is controlled40℃, n (catalyst):n(1-octene)=1:250, hydrolysis reaction maintains the pH at12to13, the hydrolysis reaction temperature is40℃, the hydrolysis reaction time is2h, the desired product1,2-octanediol yield is up to91.2%.