| 摘要 |
<p>Diesters of dibasic acids and tetraesters of tetrabasic acids, capable of forming internal anhydrides, are prepared by reaction of said anhydrides with sulphites derived from aliphatic primary alcohols having not more than 16 carbon atoms or phenols in the presence of, as catalyst, alkali metal salts of organic carboxylic acids or inorganic acids, at a temperature in the range of from 100 to 200 DEG C. Examples of anhydrides which may be used and the anhydrides of phthalicacid and its substitution and hydrogenation products, pyromellitic, naphthalic, prehnitic, diphenic, maleic and succinic acids and their substitution products. Suitable sulphites are dialkyl sulphites in which the alkyl groups may be the same or different and may contain substituents and/or may be interrupted by oxygen atoms, for example, dimethyl, diethyl, bismethoxyethyl, di-n-butyl, di-(2-ethylhexyl), diphenyl and ethylbutyl sulphite. From 0.1 to 5% by weight of catalyst may be used, examples of catalysts being lithium bromide and chloride; potassium fluoride, bromide, diphthalate, bicarbonate and sulphate. In carrying out the reaction, it is generally preferable to use a quantity of sulphite greater than that stoichiometrically required.</p> |
