METHOD OF SYNTHESIS OF HYDROXYALKYLCARBOXYMETHYL-STARCH Russian patent published in 2002 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: method of synthesis of hydroxyalkylcarboxymethyl-starch involves the preparing a homogenized reactive mixture from starch, monochloroacetic acid sodium salt, sodium hydroxide an aqueous solution into high-effective mixers of blade of anger type and esterification. In the process of preparing the reactive mixture monochloroacetic acid sodium salt is added in the amount 0.1-0.2 mole per 1 anhydroglucose starch link. Then the prepared reactive mixture is fed into autoclave where a mixture is treated with a hydroxyalkylating agent taken in the amount 0.1-0.3 mole per 1 an anhydroglucose starch link at temperature from 35 to 82 C for 0.5-3.0 h. Then the obtained product is dried at temperature 60-90 C for 0.5-2.0 h. Method provides preparing water-swelling hydroxyalkylcarboxymethyl-starch with the substitution degree by carboxymethyl groups = 0.07-0.15 and the mole substitution by hydroxyalkyl groups = 0.05-0.10 that provides the required properties in their using as a water-retaining agent in drilling solutions, namely, high swelling rate, enhanced salt resistance, water loss and an uniform fine-grained structure and friability. EFFECT: improved method of preparing, valuable properties. 5 cl, 3 tbl