A process for preparing an ester of a cellulose ether comprises the steps of reacting a cellulose ether with a dicarboxylic acid anhydride or with a combination of a dicarboxylic acid anhydride and an aliphatic monocarboxylic acid anhydride, wherein the esterification is conducted i) in the absence of an esterification catalyst or in the presence of no more than 0.1 mole of an esterification catalyst per mole of anhydroglucose units of cellulose ether, and ii) in the presence of an aliphatic carboxylic acid, wherein the molar ratio [aliphatic carboxylic acid/anhydroglucose units of cellulose ether] is up to 12/1.

A process for preparing an ester of a cellulose ether comprises the steps of reacting a cellulose ether with a dicarboxylic acid anhydride or with a combination of a dicarboxylic acid anhydride and an aliphatic monocarboxylic acid anhydride, wherein the esterification is conducted i) in the absence of an esterification catalyst or in the presence of no more than 0.1 mole of an esterification catalyst per mole of anhydroglucose units of cellulose ether, and ii) in the presence of an aliphatic carboxylic acid, wherein the molar ratio [aliphatic carboxylic acid/anhydroglucose units of cellulose ether] is up to 12/1.

The present invention relates to esters of diacids and cellulosic materials and methods for making thereof. The ester has the chemical composition of Formula (I) Formula I where R1, R2, and R3 can be the same or different, and each of which is selected from H, COR, R, or COR COOH, with the proviso that at least one of the R1, R2, or R3 is COR COOH; R is an alkyl, alkenyl, alkynyl, or aromatic group; R is an alkyl, alkenyl, or alkynyl group having 4 or more carbon atoms (C.sub.4); and R is an alkyl, alkenyl, alkynyl, polyol, or aromatic group.

The present invention relates to esters of diacids and cellulosic materials and methods for making thereof. The ester has the chemical composition of Formula (I) Formula I where R1, R2, and R3 can be the same or different, and each of which is selected from H, COR, R, or COR COOH, with the proviso that at least one of the R1, R2, or R3 is COR COOH; R is an alkyl, alkenyl, alkynyl, or aromatic group; R is an alkyl, alkenyl, or alkynyl group having 4 or more carbon atoms (C.sub.4); and R is an alkyl, alkenyl, alkynyl, polyol, or aromatic group.

An aqueous composition useful for producing capsules shells comprises a) at least one dispersed esterified cellulose ether comprising (i) groups of the formula C(O)RCOOA or (ii) a combination of aliphatic monovalent acyl groups and groups of the formula C(O)RCOOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, and b) from 0.05 to 20 percent of at least one salt of a fatty acid, based on the weight of the dispersed esterified cellulose ether, wherein the median particle size, d50, of the dispersed esterified cellulose ether particles is up to 7 micrometers, such median particle size (d50) being the size at which 50 mass percent of the particles have a smaller equivalent diameter and 50 mass percent have a larger equivalent diameter.

An aqueous composition useful for producing capsules shells comprises a) at least one dispersed esterified cellulose ether comprising (i) groups of the formula C(O)RCOOA or (ii) a combination of aliphatic monovalent acyl groups and groups of the formula C(O)RCOOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, and b) from 0.05 to 20 percent of at least one salt of a fatty acid, based on the weight of the dispersed esterified cellulose ether, wherein the median particle size, d50, of the dispersed esterified cellulose ether particles is up to 7 micrometers, such median particle size (d50) being the size at which 50 mass percent of the particles have a smaller equivalent diameter and 50 mass percent have a larger equivalent diameter.

An esterified cellulose ether which comprises (i) aliphatic monovalent acyl groups or (ii) groups of the formula C(O)RCOOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, or (iii) a combination of aliphatic monovalent acyl groups and groups of the formula C(O)RCOOA, and which has a) a viscosity of from 1.2 to 1.8 mPaos, measured as a 2.0 wt % solution of the esterified cellulose ether in 0.43 wt % aqueous NaOH at 20 C., or b) a viscosity of up to 5 mPa.Math.s, measured as a 10 wt % solution of the esterified cellulose ether in acetone at 20 C., or c) a combination of the viscosities of a) and b), is useful for preparing solid dispersions comprising drugs.

An esterified cellulose ether which comprises (i) aliphatic monovalent acyl groups or (ii) groups of the formula C(O)RCOOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, or (iii) a combination of aliphatic monovalent acyl groups and groups of the formula C(O)RCOOA, and which has a) a viscosity of from 1.2 to 1.8 mPaos, measured as a 2.0 wt % solution of the esterified cellulose ether in 0.43 wt % aqueous NaOH at 20 C., or b) a viscosity of up to 5 mPa.Math.s, measured as a 10 wt % solution of the esterified cellulose ether in acetone at 20 C., or c) a combination of the viscosities of a) and b), is useful for preparing solid dispersions comprising drugs.

A process for recovering an esterified cellulose ether from a reaction product mixture obtained from a reaction of (a) a cellulose ether with (b) an aliphatic monocarboxylic acid anhydride or a di- or tricarboxylic acid anhydride or a combination of an aliphatic monocarboxylic acid anhydride and a di- or tricarboxylic acid anhydride, comprises the steps of (i) contacting the reaction product mixture with an aqueous liquid to precipitate the esterified cellulose ether from the reaction product mixture, (ii) isolating the precipitated esterified cellulose ether from the mixture obtained in step (i), and (iii) suspending the isolated esterified cellulose ether in an aqueous liquid to provide a suspension having a temperature of at least 28 C., and (iv) recovering the esterified cellulose ether from the suspension of step (iii).

A process for recovering an esterified cellulose ether from a reaction product mixture obtained from a reaction of (a) a cellulose ether with (b) an aliphatic monocarboxylic acid anhydride or a di- or tricarboxylic acid anhydride or a combination of an aliphatic monocarboxylic acid anhydride and a di- or tricarboxylic acid anhydride, comprises the steps of (i) contacting the reaction product mixture with an aqueous liquid to precipitate the esterified cellulose ether from the reaction product mixture, (ii) isolating the precipitated esterified cellulose ether from the mixture obtained in step (i), and (iii) suspending the isolated esterified cellulose ether in an aqueous liquid to provide a suspension having a temperature of at least 28 C., and (iv) recovering the esterified cellulose ether from the suspension of step (iii).