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Efficient process of preparing an esterified cellulose ether

A technology for esterifying cellulose ether and cellulose ether, which is applied in the field of preparing esterified cellulose ether and can solve the problems of affecting the color of esterified cellulose ether, etc.

Inactive Publication Date: 2019-05-24
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Disadvantageously, very harsh conditions have to be applied to obtain cellulose ethers of less than 3 mPa s, which affects the color of partially depolymerized cellulose ethers and correspondingly the color of esterified cellulose ethers produced therefrom

Method used

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  • Efficient process of preparing an esterified cellulose ether
  • Efficient process of preparing an esterified cellulose ether
  • Efficient process of preparing an esterified cellulose ether

Examples

Experimental program
Comparison scheme
Effect test

example

[0046] All parts and percentages are by weight unless otherwise indicated. In the examples, the following test procedure was used.

[0047] Viscosity of hydroxypropylmethylcellulose acetate succinate (HPMCAS)

[0048] A 10 wt% solution of esterified cellulose ether in acetone was determined by first determining the loss on drying of HPMCAS according to "Hypromellose Acetate Succinate USP and National Formulary, NF 29, pp. 1548-1550" preparation. 10.00 g of HPMCAS by dry weight were then mixed with 90.0 g of acetone at room temperature under vigorous stirring. The mixture was rolled on a roller mixer for about 24 hours. The solution was centrifuged at 2000 rpm for 3 minutes using a Megafuge 1.0 centrifuge (available from Heraeus Holding GmbH, Germany), followed by Ubbelohde viscosity measurements according to DIN 51562-1:1999-01 (January 1999). Measurement.

[0049] Ether group and ester group content of HPMCAS

[0050] The content of ether groups in the esterified cel...

example 2

[0076] HPMCAS of Production Example 2

[0077] Example 1 was repeated except that the amounts of HPMC, acetic acid, sodium acetate, acetic anhydride, and succinic anhydride were as listed in Table 1 below.

[0078] HPMCAS of Production Example 3

[0079] Example 1 was repeated except that the amounts of HPMC, acetic acid, sodium acetate, acetic anhydride, and succinic anhydride were as listed in Table 1 below.

[0080] Production of the HPMCAS of Comparative Example B

[0081] The same mixture of HPMC, glacial acetic acid and sodium acetate as in Example 2 was heated to 85°C. Then, succinic anhydride was added to the mixture in the amount listed in Table 1 below, and three minutes later acetic anhydride was added to the mixture. The amounts of succinic anhydride and acetic anhydride were selected to achieve about the same degree of substitution with acetyl groups and about the same degree of substitution with succinyl groups as in Example 2.

[0082] The reaction was...

example 5

[0100] Example 5 demonstrates that even when HPMC with a viscosity of 5.3 mPa·s is used as starting material, a low weight average molecular weight and a rather low viscosity in acetone of HPMCAS is obtained. It is desirable to use this type of HPMC; less severe depolymerization conditions are required than for the production of lower viscosity HPMC. This favorably affects the color of HPMC and the HPMCAS produced therefrom.

[0101] The comparison between Examples 3, 2 and 1 demonstrates that the molar ratio of aliphatic carboxylic acid, such as acetic acid, to anhydroglucose units of cellulose ether can be reduced in the process of the invention without increasing the weight average molecular weight and the HPMCAS produced. Viscosity in acetone.

[0102] In contrast, comparisons between Comparative Examples C and B and between Comparative Examples E and D, respectively, show that the weight average molecular weight and the produced The viscosity of HPMCAS in acetone is sig...

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Abstract

An esterified cellulose ether is produced in a highly efficient manner in a process for reacting a cellulose ether with an aliphatic monocarboxylic acid anhydride and a dicarboxylic acid anhydride, wherein the process comprises the steps of a) preparing a reaction mixture comprising the cellulose ether, the aliphatic monocarboxylic acid anhydride and the aliphatic carboxylic acid such that the molar ratio of aliphatic carboxylic acid to anhydroglucose units of cellulose ether is up to 9.0:1 and heating the reaction mixture to a temperature of from 60 DEG C to 110 DEG C prior to, during or after mixing the components of the reaction mixture, and b) keeping the reaction mixture at least 15 minutes at the temperature of from 60 DEG C to 110 DEG C before adding dicarboxylic acid anhydride to the reaction mixture.

Description

technical field [0001] The present invention relates to an efficient process for the preparation of esterified cellulose ethers. Background technique [0002] Esters of cellulose ethers, their use and methods for their preparation are generally known in the art. Known methods of producing cellulose ether-esters include the reaction of cellulose ethers with aliphatic mono- or dicarboxylic anhydrides or combinations thereof, as described, for example, in US Patent Nos. 4,226,981 and 4,365,060. [0003] Esters of various known cellulose ethers are suitable as enteric polymers for pharmaceutical dosage forms, such as methylcellulose phthalate, hydroxypropylmethylcellulose phthalate, methylcellulose Succinate or hydroxypropylmethylcellulose acetate succinate (HPMCAS). Enteric polymers are those that resist dissolution in the acidic environment of the stomach. Dosage forms coated with such polymers protect the drug from inactivation or degradation in an acidic environment or pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B13/00
CPCC08B13/00C08B15/04
Inventor M·布拉克哈根O·彼得曼R·凯琳
Owner DOW GLOBAL TECH LLC
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