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以苄基苯基醚为模型分子,氧气为氧化剂,考察了N-羟基邻苯二甲酰亚胺(NHPI)对分子氧氧化木质素醚键(α-O-4)的催化作用和多种可溶性过渡金属盐的助催化作用,探究了NHPI和硝酸铜用量、反应温度、反应时间和氧气分压对反应的影响。结果表明:NHPI催化分子氧氧化苄基苯基醚生成苯甲醛和苯酚,在可溶性的钴、锰、镍和铜盐中,铜盐对NHPI的助催化作用最好。在NHPI/Cu(NO3)2催化下,当氧分压高于0.5 MPa时,苄基苯基醚的氧化反应对氧气为0级。过高温度会加剧目标产物苯甲醛和苯酚的深度氧化。优化的工艺条件为,以乙酸为溶剂,n(苄基苯基醚)∶n(NHPI)∶n(硝酸铜)=1.0∶0.2∶0.02,氧气分压为1.0 MPa时,在110℃下反应15h,苄基苯基醚的转化率为37.2%。
Using benzyl phenyl ether as model molecule and oxygen as oxidant, the catalytic activities of N-hydroxyphthalimide (NHPI) on the molecular oxygen-oxidation of lignin ether bond (α-O-4) The catalytic effect of soluble transition metal salts was investigated. The effects of NHPI and Cu (superscript 2 +) content, reaction temperature, reaction time and partial pressure of oxygen on the reaction were investigated. The results showed that NHPI catalyzed the molecular oxidation of benzyl phenyl ether to benzaldehyde and phenol. Among the soluble cobalt, manganese, nickel and copper salts, copper salts had the best catalytic activity for NHPI. Under the NHPI / Cu (NO3) 2 catalysis, when the partial pressure of oxygen is higher than 0.5 MPa, the oxidation reaction of benzyl phenyl ether is 0 on oxygen. Excessive temperature exacerbates the deep oxidation of the target benzaldehyde and phenol. The optimized process conditions were as follows: the reaction was carried out at 110 ℃ with acetic acid as solvent, n (benzylphenylether): n (NHPI) :n (cupric nitrate) = 1.0: 0.2: 0.02 and oxygen partial pressure of 1.0 MPa 15h, the conversion of benzyl phenyl ether was 37.2%.