Cellulose ethers purification

Uses. May occur as an intermediate in the production of chlorinated ethylenes formerly used as a solvent for cellulose ethers, resins, and gums, for dry cleaning, coal purification, as a soil sterilizing agent, and as a chemical intermediate in the production of dichloroacetic acid... 

For the synthesis of cellulose ether esters at industrial scale, purified cellulose ether is reacted with carboxylic anhydrides in acetic acid as solvent system and sodium acetate as catalyst. The dissolved cellulose ether ester is being obtained then by precipitation after addition of water. Purification is performed by washing with water. 

Bulk cellulose is a poor affinity-chromatographic matrix its principal advantage is its low cost. This is rarely an overriding consideration since the enzymes to be purified are usually expensive. Cellulose was employed in 1953 in one of the earliest affinity-chromatography separations, where tyrosinase was purified on a column of aromatic cellulose ethers (27). Currently, cellulose (28) or related polysaccharides (29) are used in a number of applications as a bioselective adsorbent including DNA-cellulose for the purification of DNA-binding proteins. 

The purified form of cellulose, obtained from cotton linters or wood pulp, is treated with sodium hydroxide solution to produce swollen alkali cellulose that is chemically more reactive than untreated cellulose. Reaction of the alkali cellulose with chloro-methane and propylene oxide produces methyl hydroxypropyl ethers of cellulose. Further purification of the fibrous reaction product is done and is grounded to fine, uniform powder or granules. 

The manufacturing process for organo-soluble EHEC is similar to that for EC except that alkah cellulose reacts first with ethylene oxide to a low hydroxyethyl MS value of - 0.5 at a low temperature, - 50° C, followed by reaction of the ethyl chloride at a higher temperature. Additional by-products, which are removed during purification, include glycols and the reaction products of the glycols with ethyl chloride (glycol ethers). 

Cellulose for chromatography is purified by sequential washing with chloroform, ethanol, water, ethanol, chloroform and acetone. More extensive purification uses aqueous ammonia, water, hydrochloric acid, water, acetone and diethyl ether, followed by drying in a vacuum. Trace metals can be removed from filter paper by washing for several hours with O.IM oxalic or citric acid, followed by repeated washing with distilled water. 

CCOOC3Ha)2 mw 146.14, col, unstable aromatic liquid combustible but not flammable sp gr 1-079 at 20/4° (Lange), 1.09 at 20/20° (Ref 3), fr P -40.6°, bp 185-4-186° fl p 168°F v si isol in w with gradual deoompn miscible with ale, eth, eth acetate and other common org solvents. Can be prepd by standard esterification procedure using ethanol oxalic acid. The final purification, however calls for specific technique and equipment (Ref 3). Used as solvent for cellulose esters ethers and for synthetic resins also for radio tube cathode fixing lacquers, pharmaceuticals, etc... 

The methyl ether of cellulose has a methoxyl content which varies between 6 and 33 %. Methylcellulose can be prepared by the action of methyl chloride or methyl sulfate on cellulose that has been previously treated with alkali. Purification is accomplished by washing the reaction product with hot water. The degree of methylation can be controlled to yield products with varying viscosities. Seven viscosity types of methylcellulose are currently produced with centipoise values ranging from 10 to 4000. Methylated cellulose of low methoxy content is soluble... 

Without further purification, the compound is freed from the protective groups by standing for 1 hour in 80-90% trifluoroacetic acid containing some thioglycolic acid, and is subsequently precipitated by adding 150 ml of ether. Yield 3.06 g of crude peptide-trifluoroacetate. After purification on carboxymethyl cellulose, 1.45 g of the chromatographically pure peptide are obtained in the form of acetate. [a]D20 -68.6°-2° (c=0.5 in 1% acetic acid). Amino acid analysis ... 

The aralkyl celluloses, e.g., benzylcellulose and phenylethylcellulose, are made in a similar manner. Their purification may be accomplished by treating the crude alkylation mass with a selective solvent, e.g., propanol or diamyl ether, which removes organic impurities. The granular precipitate is then washed with methanol and finally with water. 

Materials. VEC was prepared by the catalyzed addition of CO2 to 3,4-epoxy-l-butene using conditions typical of that used industrially [77], then purified by vacuum distillation. Other raw materials were used as received without any additional purification. Mixed xylenes, vinyl acetate (VA), butyl acrylate (BA), butyl methacrylate (BMA), methyl methacrylate (MMA), styrene (St), and t-butyl hydroperoxide were obtained from Aldrich Chemical Company. Lupersol 575 (t-amyl peroxy (2-ethylhexanoate)) was supplied by Elf Atochem. Vazo 67 (2,2 -azobis(2-methylbutyronitrile)) was obtained from DuPont Chemical Company. Vinyl pivalate (NE05), vinyl 2-ethylhexanoate (V2EH), Tergitol NP-40 (non-ionic surfactant) and QP-300 (hydroxy ethyl cellulose) were obtained from Union Carbide Coq)oration. Aerosol OT-75 (surfactant) was obtained from Cytec. Sodium formaldehyde sulfoxylate was obtained from Henkel Corporation. Ethyl 3-ethoxy propionate (EEP), propylene glycol monomethyl ether (PM) and PM acetate (PM Ac) are Eastman Chemical Company products. 

Sulfolane is used as a polymerization solvent for the production of polysulfones, polysiloxanes, polyphenylene ethers, and other polymers. Sulfolane is said to increase the reaction rates, afford easier polymer purification, and improved thermal stability. Sulfolane is a solvent for dissolving a variety of polymers for use in the fiber-spinning process. Cellulose and cellulose ester polymers can be plasticized with sulfolane to give improved flexibility and other physical property improvements [12,13]. Other application areas that have used sulfolane include electronic and electrical, textile-dye uses, curing of polysulfide sealant, and as a catalyst in certain synthetic reactions. 

M. Niang and G. Luo, A triacetate cellulose membrane for the separation of methyl tert-butyl ether/methanol mixtures by pervaporation. Separation and Purification Technology 24 (2001) 427-435. 

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