Selective Oxidation Of Cyclopentene To Glutaraldehyde Catalyzed By Heteropoly Organic-inorganic Salt

Glutaraldehyde?GA?is widely used as a disinfectant bactericide in many fields.A strong competitive synthesis method of GA has been developed in a one-step route through the selective oxidation of cyclopentene?CPE?.Catalytic process generally includes homogeneous catalysis and heterogeneous catalysis.Homogeneous catalysts usually exhibit high activity but have difficulty in separation,recovery and reuse.On the contrary,heterogeneous catalysts exhibit facile separation and recycling but always suffer from inferior activity,long reaction time,leaching of the active species,which limits its further application.The reaction-controlled phase-transfer catalysis system not only realizes the catalyst recovery from the product over homogeneous catalysis but also avoids the low reaction rate,leaching of the active species and low selectivity in heterogeneous catalysis.Several new reaction-controlled phase-transfer catalysis systems have been developed for the preparation of GA from the oxidation of CPE,and several heterogeneous catalysis systems with high catalytic activity for the oxidation of CPE have also been established.This paper mainly includes four parts as follows:?1?Byusingmethylimidazole,pyridine,N,N-dimethylbenzylamine,or hexadecylpyridinium chloride as cations,and phosphotungstic acid or Dawson's structure PW₄O₁₆^3-and PW₄O₃₂^3-as anions,nine kinds of ionic liquid catalysts were synthesized and used to catalyze the selective oxidation of cyclopentene?CPE?to glutaraldehyde?GA?.The selected optimum catalyst is[?-C₅H₅NC₁₆H₃₃]₃PW₄O₁₆6 and it was characterized by FT-IR,³¹P MAS NMR,and elementary analysis.Then,the reaction-controlledphase-transfercatalysisof[?-C₅H₅NC₁₆H₃₃]₃PW₄O₁₆in1,2-dichloroethane was studied.The optimum reaction conditions obtained are as follows:n?Cat.?:n?H₂O₂?:n?CPE?=0.05:1.2:1,t=8 h,T=35^oC.Under the optimum reaction conditions,a high GA yield of 78%with complete conversion of CPE is obtained.After recycling the catalyst five times,the GA yield is still higher than 60%.Furthermore,the heterogeneous catalysis for catalytic selective oxidation of CPE to GA in ethyl acetate over the[?-C₅H₅NC₁₆H₃₃]₃PW₄O₁₆6 catalyst was fully investigated.Under the optimum reaction conditions?n?Cat.?:n?H₂O₂?:n?CPE?=0.03:1.5:1,t=18 h,T=35^oC?,the conversion of CPE is 100%,and the yield of GA is 87%.After the catalyst was recycled seven times,the yield of GA was still higher than 80%.?2?By using the intermediate synthesized by methylimidazole,pyridine,N,N-dimethylbenzylamine or N,N-dimethylhexadecane-1-amine,and 1,3-propyl sulfonic acid lactone as the cations,and phosphotungstic acid or Dawson's structure PW₄O₁₆^3-and PW₄O₃₂^3-as the anions,16 kinds of acidic-oxidative dual functional ionic liquid catalysts were synthesized and used to catalyze the selective oxidation of CPE to GA.Among these catalysts,[C₁₆H₃₃N?CH₃?₂?CH₂?₃SO₃H]₃PW₄O₁₆6 exhibited the best catalytic activity and then was characterized by FT-IR,¹H NMR,and TG.By using[C₁₆H₃₃N?CH₃?₂?CH₂?₃SO₃H]₃PW₄O₁₆6 as the catalyst,the effects of various factors,i.e.,the amount of the catalyst,molar ratio of H₂O₂ to CPE,type and dosage of solvent,reaction temperature,and reaction time,on the catalytic behaviors were fully investigated and discussed.The results showed that the best reaction conditions are as follows:5 m L of acetone,n?Cat.?:n?H₂O₂?:n?CPE?=0.05:2.2:1,t=8 h,T=35 ^oC.The conversion of CPE could reach 97%,and the yield of GA was 65%.?3?A series of heteropoly organic-inorganic salts doped with metal ions such as Ti???,Mn???,Co???,and Zr???with the function of reaction-controlled phase-transfer were synthesized and used to catalyze the selective oxidation of CPE to GA.Among these catalysts,[?-C₅H₅NC₁₆H₃₃]₂Ti_1/4PW₄O₃₂2 exhibited the best catalytic activity.The results showed that the best reaction conditions as follows:n?Cat.?:n?H₂O₂?:n?CPE?=0.05:1.5:1,t=12 h,T=35^oC.The conversion of CPE could reach 100%and the yield of GA was 81%.After recycling five times,the yield of GA was still above 76%.?4?A series of heteropoly organic-inorganic salts doped with metal ions Fe???and Ti???were synthesized and used to catalyze the selective oxidation of CPE to get GA.Amongthesecatalysts,[C₆H₅N?CH₃?₂?CH₂?₃SO₃H]₂Fe_1/3PW₄O₁₆and[C₆H₅N?CH₃?₂?CH₂?₃SO₃H]Ti_1/2PW₄O₁₆6 exhibited the best catalytic activity.By using[C₆H₅N?CH₃?₂?CH₂?₃SO₃H]₂Fe_1/3PW₄O₁₆6 as the catalyst,the effects of various factors on the catalytic behaviors were fully investigated and discussed.The results showed that the best reaction conditions are as follows:n?Cat.?:n?H₂O₂?:n?CPE?=0.05:2:1,t=6 h,T=35^oC.The conversion of CPE could reach 99%,and the yield of GA was 64%.By using[C₆H₅N?CH₃?₂?CH₂?₃SO₃H]Ti_1/2PW₄O₁₆6 as the catalyst,the effects of various factors,i.e.,the amount of the catalyst,molar ratio of H₂O₂ to CPE,type and dosage of solvent,reaction temperature,and reaction time were fully investigated and discussed.The results showed that the best reaction conditions are as follows:5 mL of acetone,n?Cat.?:n?H₂O₂?:n?CPE?=0.05:2:1,t=3 h,T=35 ^o C.The conversion of CPE could reach 99%,and the yield of GA was 69%.This thesis presents many routes for the catalytic oxidation of cyclopentene to glutaraldehyde by reaction-controlled phase-transfer catalysis and heterogeneous catalysis of organic-inorganic heteropoly acid salts as catalysts.The study has important theoretical significance and wide application prospect.