GB755461A - Improvements in or relating to sulfation of amylaceous materials - Google Patents

Abstract

A sulphated amylaceous product is obtained by reacting an amylaceous material in the presence of at least 10 per cent water, based on the anhydrous amylaceous material, and sufficient alkali to achieve a pH of at least 9, with a reagent comprising the addition product of sulphur trioxide and a tertiary amine. The term "amylaceous material" includes starches obtained from corn, wheat, tapioca, waxy maize, sago, potato, sweet potato, and rice. The starch may be in its native state or it may have been converted by heat, acids, oxidizing agents or other chemical means to thin-boiling starch, dextrin, starch ethers, esters or other derivatives. The sulphur trioxide-tertiary amine addition product may be obtained by mixing the two components, or by reacting a tertiary amine with chlorsulphonic acid. The trimethylamine-sulphur trioxide addition product may be made by reaction of dimethyl sulphate and tetramethyl sulphamide. The tertiary amine may be aliphatic, aromatic, aryl aliphatic or heterocyclic. Suitable amines are trimethylamine, triethylamine, tripropylamine, tributylamine, N-ethyl morpholine, N-methyl morpholine, dimethyl benzylamine, diethyl benzylamine, methyl diethylamine and pyridine. The starch may be suspended or dispersed in water during the reaction, or the process may be effected on dry starch provided the reaction mass contains at least 10 per cent water. The alkali used may be an hydroxide or weak acid salt of an alkali metal or alkaline earth metal or a quaternary hydroxide. Thus, sodium, potassium or calcium hydroxide, trisodium phosphate, sodium carbonate or quaternary ammonium hydroxide may be used. The reaction may be effected at room temperature or with heating and agitation. The product may be neutralized to remove excess alkali. The product may be obtained in ungelatinized form by avoiding gelatinizing conditions, e.g. excessive heat or alkali, or by adding sodium sulphate. Alternatively gelatinized starch may be used initially or gelatinizing conditions may be employed. The sulphated starch product dispersion may be used as such, precipitated by pouring into alcohol, or dried, e.g. over heated drums. The amount of the sulphur trioxideamine addition product used may vary from 0.1 per cent to 450 per cent by weight based on the starch. Detailed examples are given in which corn starch in native form, reacted with epichlorhydrin, oxidized with hypochlorite, acid converted or acetylated, is reacted in the presence of sodium hydroxide or phosphate with a sulphur trioxide-tertiary amine addition product as described.