| 摘要 |
<p>Fumaric acid is obtained by contacting aqueous maleic acid solution with a bromine-providing material wherein the oxidation state of the bromine is less than plus 5, and an oxidizing agent, the initial concentration of the maleic acid solution being from 10% to 70% by weight, the bromine-providing material being present in an amount equivalent in bromine content to at least 0.001% of ammonium bromide based on the weight of maleic acid, the oxidizing agent having a standard oxidation reduction potential of at least 1.23 volts and being present in an amount oxidatively equivalent to from 0.003% to 10% of ammonium persulphate based on the weight of the maleic acid. The process is carried out at 70 DEG to 100 DEG C. and the mixture is then cooled to form crystalline fumaric acid. In examples fumaric acid is obtained from maleic acid using cadmium ammonium bromide, ammonium bromide, and ammonium persulphate. Other bromine-containing materials mentioned are sodium bromide, hydrogen bromide, manganese bromide, elemental bromine, and N-bromosuccinimide. Other oxidizing agents mentioned are hydrogen peroxide, peracetic acid, perbenzoic acid, cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, lauroyl peroxide, t-butyl peroxide, sodium perborate and chlorates. Specification 958,695 is referred to.</p> |
