Venture Chemicals, Inc.

Tammy L Rodrigue

Jack C Cowan

Roy F House

Andre′ N Blanchard

Catherine G Benoit

Disclosed is a process for the deacetylation of chitin and a process for the treatment of chitinaceous materials to obtain chitin which processes are conducted in a non-saponifiable, non-aqueous, water insoluble liquid having a flash point greater than about 100&#xb0; C., preferably a non-aromatic hydrocarbon. The process for the deacetylation of chitin comprises suspending chitin in the hydrocarbon liquid, preferably from about 0.02 g/cc to about 0.2 g/cc, mixing therewith an alkali metal hydroxide solution, and heating the suspension at a temperature at least about 70&#xb0; C. for a period of time sufficient to obtain the desired degree of deacetylation. The concentration of alkali metal hydroxide in the alkali metal hydroxide solution is at least 30% by weight, preferably at least 40% by weight, and most preferably at least 50% by weight, and the quantity of alkali metal hydroxide is sufficient to provide an alkali metal hydroxide to chitin weight ratio from about (0.35)(AMHMW)/40 to about (2.5)(AMHMW)/, 40 where AMHMW is the molecular weight of the alkali metal hydroxide.

Process for the treatment for chitinaceous materials and for the deacetylation of chitin

The invention provides an organic diacid anhydride-modified chitosan and a method of preparing the same under high shear conditions which eliminates the use of solvents and excessive amounts of aqueous liquids. Also provided are organic diacid anhydride-modified chitosans containing an inorganic basic material which enhances the aging stability thereof. The invention also provides fluids useful in various well drilling and servicing operations comprising an alkaline aqueous liquid containing an organic diacid anhydride-modified chitosan, as well as a method of drilling wells therewith.

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St. Martinville, LA, United States of America

Tammy L Rodrigue