Carboxymethyl ethers, preparation

Carboxymethylcellulose Sodium. Carboxymethyl ether of cellulose sodium salt (Citmcel) (8) is a white granular substance soluble in water depending on the degree of substitution. It is equally soluble in cold and hot water and may be prepared by treating alkaU cellulose with sodium chloroacetate. 

Carboxymethylcelluloses (CMC). CarboxymethylceUulose [9004 2-6] (CMC) is the carboxymethyl ether of cellulose. To prepare CMC, cellulose is steeped in sodium hydroxide solution, and the so-called alkaU cellulose is treated under controlled conditions with sodium monochloroacetate to form the sodium salt of CarboxymethylceUulose and sodium chloride. Therefore, the CMC of commerce is actuaUy sodium CarboxymethylceUulose... 

Calestani et al. [8] prepared dietylamide of the tetra-carboxymethyl ether of p-tert-h W.y calix[4]arene and reported alkali metal picrate extraction constants of 1.9... 

Total hydrolysis of the polymers gave D-glucose only. Water-soluble derivatives (ethyl or carboxymethyl ethers) of the polymers were unaffected by a-amylase, but were partially hydrolyzed by a ceUulase preparation from Acdobader xylinum. The optical rotations of several preparations of this polyglucose and of cellulose (P 1150) in tetraethylammonium hydroxide were all 0°, thereby strongly suggesting that the polyglucoses are /S-D-linked.109... 

A homolog of carboxymethylcellulose, the carboxyethyl derivative, can be prepared by the condensation of such acrylic derivatives as acrylamide with alkali-cellulose.30 The homolog is water-soluble, and gives a clear, viscous solution. Proposed uses are similar to those mentioned for the carboxymethyl ether. 

The only anionic group added to cellulose is the carboxymethyl (-0-CH2-C02 ) ether group. To introduce the carbox)miethyl group, alkali cellulose is reacted with chloroacetic acid. (The carboxymethyl ether is also the ether of glycolic acid.) Also prepared commercially is car-boxymethylhydroxyethylcellulose. 

Like cellulose and starch, locust bean gum is able to form derivatives through reaction of the hydroxyl groups. The methyl ether has been prepared for constitutional work. For the time being only the water-soluble derivatives (hydroxyethyl and carboxymethyl ether) are of practical interest. They are used as alkali-resistant printing thickeners. 

Investigation into the formation of carboxymethyl ethers of polysaccharides has continued, on account of the great utility of these derivatives as ion-exchange materials and polyelectrolytes. As expected, a whole series of polysaccharide derivatives of different degrees of substitution can be prepared by variation of the reaction conditions and molar proportions of monochloroacetic acid. " Published reports include the preparation of various carboxymethyl ethers of starches, amyloses, lichenan, pachymans, and chitin and introduction of the carboxymethyl group into polysaccharide derivatives constitutes a useful way of raising their solubility in water. By combining the introduction of alkyl and carboxy-... 

Derivatives of chitin, ethers, esters, and a sodio derivative, have been discussed, and the carboxymethyl ether of chitin has been prepared by the standard method of carboxymethylation. ... 

Sucrose ethers and esters were analyzed as tri-methylsilyl derivatives prepared by adding to 0,5 ml of reaction solution, 0,1 ml hexeimethyldisilazane and 0,05 ml dimethylchlorosilane. The carboxymethyl ethers were gas-chromatographically separated on a 12 ft 3% OV-17 glass column at first with the temperature programmed at 180°-280°C, 4°/min, and then isothermally. 

Carboxymethyl ethers can be prepared by reaction of alkaline polysaccharide with chloroacetate at 30-80°C to achieve d.s. values of 0.8 to 1.1 [8,10] (reaction 7.6). Carboxymethyl cellulose (CM-cellulose) was first developed in Germany in 1916, and then in 1935, it was found that it improved the performance of synthetic detergents [11]. CM-cellulose has since found wide application in textiles, detergents, foods, pharmaceuticals, cosmetics, oil and gas drilling muds, paper, adhesives, coatings, ceramics, suspending agents, and emulsions [11]. 

Sodium azide does not react with carbonyl sulfide to form 5-hydroxy-1,2,3,4-thiatriazole, nor with carboxymethyl xanthates, RO-CS SCH2COOH, to form 5-alkoxy-l,2,3,4-thiatriazoles. The latter, however, could be prepared from xanthogenhydrazides (RO-CS NHNH2) and nitrous acid. They are very unstable and may decompose explosively at room temperature only the ethoxy compound (6) has been examined in detail. This is a solid which decomposes rapidly at room temperature and even at 0°C is transformed after some months into a mixture of sulfur and triethyl isocyanurate. In ethereal solution at 20° C the decomposition takes place according to Eq. (16)... 

Carboxymethylcellulose Calcium (Calcium CMC) A calcium salt of polycar-boxymethyl ether of cellulose, calcium CMC is obtained by carboxymethylation of cellulose and conversion into calcium salt. Different molecular grades are prepared by changing the degree of carboxymethylation. It is available as a line powder, white to yellowish white in color, and hygroscopic in nature. Calcium CMC has swelling and viscosity-enhancing properties in water. It can swell twice its volume in water [25]. 

Testosterone-3-(0-carboxymethyl) Oxime. This compound is prepared according to the general method of Erlanger et al. Testosterone dissolved in ethanol is refluxed for 3 hr with a solution of 0-(carboxy-methyl)hydroxylamine in 2 N KOH. The ethanol is then removed by evaporation, water is added, and the mixture is washed with ethyl acetate. The aqueous solution is acidified to pH 2 with hydrochloric acid. The precipitate formed is filtered, washed with water, and recrystallized from ethyl acetate-petroleum ether. 

Carboxymethyl cellulose Usually prepared as the carboxylic salt of polycarboxymethyl ether of cellulose Dispersion of the free acid or its sodium salt is stable at a wide pH range (2-10) Thickening agent and tablet excipient... 

By use of a modification of the well-known Williamson synthesis it is possible to prepare a number of cellulose ethers. Of these materials ethyl cellulose has found a small limited application as a moulding material and somewhat greater use for surface coatings. The now obsolete benzyl cellulose was used prior to World War II as a moulding material whilst methyl cellulose, hyroxyethyl cellulose and sodium carboxymethyl cellulose are useful water-soluble polymers. 

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