Abstract

A procedure was developed for preparing glyoxylic acid by glyoxal oxidation with nitric acid in the presence of hydrohalic acids with selective isolation of glyoxylic acid from the reaction mixture in the form of magnesium and calcium salts. Specific features of the synthesis of glyoxylic acid were demonstrated, and optimum conditions for each step of the process were determined. The highest yield of glyoxylic acid was obtained in oxidation of glyoxal with an HNO₃ : HCl mixture. Oxidation in the presence of HF and HBr is characterized by lower yields because of low dissociation constant of HF and side redox reactions with HBr. Dilute solutions of glyoxylic acid were obtained by an exchange reaction of its calcium salt with a hydrofluoric acid solution at room temperature. An increase in the reaction temperature leads to an increase in the content of glycolic and oxalic acids formed by disproportionation of glyoxylic acid in the initial step of the exchange reaction.

中文翻译：

---

在氢卤酸存在下乙二醛氧化合成乙醛酸

摘要

开发了一种在氢卤酸存在下通过用硝酸乙二醛氧化乙醛酸制备乙醛酸的方法，并从反应混合物中选择性地分离出镁盐和钙盐形式的乙醛酸。证明了乙醛酸合成的具体特征，并确定了该方法每个步骤的最佳条件。在用HNO ₃氧化乙二醛中获得最高的乙醛酸收率：HCl混合物。由于HF的解离常数低以及与HBr的副氧化还原反应，因此在HF和HBr存在下的氧化特征是产率较低。乙醛酸的稀溶液通过其钙盐与氢氟酸溶液在室温下的交换反应获得。反应温度的升高导致在交换反应的初始步骤中由乙醛酸歧化形成的乙醇酸和草酸含量的增加。