Vilanculo Castelo Bandane, José da Silva Márcio
Chemistry Department, Pedagogic University of Mozambique, FCNM, Campus of Lhanguene Av. De Moçambique, Km 1 Maputo 4040 Mozambique
Chemistry Department, Federal University of Viçosa Minas Gerais State 36590-000 Brazil.
RSC Adv. 2021 Oct 28;11(55):34979-34987. doi: 10.1039/d1ra06718d. eCollection 2021 Oct 25.
The activity of the sodium salts of vanadium-doped phosphomolybdic acid was assessed in the oxidative esterification reaction of benzaldehyde with hydrogen peroxide in alkyl alcohol solutions. The effect of main reaction parameters, such as temperature, catalyst load, vanadium doping level, and reactant stoichiometry, on the conversion and reaction selectivity was investigated. Among the tested heteropoly salts, NaPMoVO was the most active and selective catalyst, achieving almost complete conversion of benzaldehyde and high ester selectivity regardless of the alcohol investigated. The efficiency of the catalyst was correlated with its vanadium content. The size of the carbon chain of alcohol and the steric hindrance on the hydroxyl group played a key role in the reaction selectivity. While methyl and ethyl alcohols selectively provided the ester as the main product ( 90-95%) and benzoic acid as a subproduct, the other alcohols also afforded acetal, a condensation product, and benzaldehyde peroxide, an oxidation reaction intermediate, as secondary products. The use of an inexpensive, environmentally benign, and atom-efficient oxidant, mild conditions, and short reaction times were the positive aspects of this one-pot process.
在烷基醇溶液中，评估了钒掺杂磷钼酸的钠盐在苯甲醛与过氧化氢的氧化酯化反应中的活性。研究了温度、催化剂负载量、钒掺杂水平和反应物化学计量比等主要反应参数对转化率和反应选择性的影响。在所测试的杂多盐中，NaPMoVO是活性最高且选择性最好的催化剂，无论研究的是哪种醇，都能使苯甲醛几乎完全转化，并具有较高的酯选择性。催化剂的效率与其钒含量相关。醇的碳链长度和羟基上的空间位阻在反应选择性中起关键作用。甲醇和乙醇选择性地以酯作为主要产物（90 - 95%），苯甲酸作为副产物，而其他醇还会生成缩醛（一种缩合产物）和过氧化苯甲醛（一种氧化反应中间体）作为次要产物。使用廉价、环境友好且原子经济的氧化剂、温和的条件以及较短的反应时间是该一锅法工艺的积极方面。
