Ethers of cellulose

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. 

Etherification. Carbohydrates are involved in ether formation, both intramoleculady and intermoleculady (1,13). The cycHc ether, 1,4-sorbitan, an 1,4-anhydroalditol, has already been mentioned. 3,6-Anhydro-a-D-galactopyranosyl units are principal monomer units of the carrageenans. Methyl, ethyl, carboxymethyl, hydroxyethyl, and hydroxypropyl ethers of cellulose (qv) are all commercial materials. The principal starch ethers are the hydroxyethyl and hydroxypropylethers (see Cellulose ethers Starch). 

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... 

These thermotropic cellulose derivatives are of course of interest from the viewpoint of their structure and properties and might be considered for such applications as chiroptical filters. However, they are unlikely to be considered for fiber formation and certainly not for regenerated fibers, as essenti dly they are ethers of cellulose and desubstitution woiild be difficult. Pawlowski et al. (I2fi) prepared a series of cellulose derivatives, namely phenylacetoxy, 4-meflioxyphenyl-acetoxy-, and p-tolylacetoxy cellulose and tnmethylsilyl cellulose that... 

The particular array of chemical shifts found for the nuclei of a given polymer depends, of course, on such factors as bond orientation, substituent effects, the nature of nearby functional groups, solvation influences, etc. As a specific example, derivatives of the carbohydrate hydroxyl moieties may give rise to chemical shifts widely different from those of the unmodified compound, a fact that has been utilized, e.g., in studies (l ) on commercially-important ethers of cellulose. Hence, as illustrated in Fig, 2, the introduction of an 0-methyl function causes (lU,15) a large downfield displacement for the substituted carbon. This change allows for a convenient, direct, analysis of the distribution of ether groups in the polymer. Analogously, carboxymethyl, hydroxyethyl and other derivatives may be characterized as well... 

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... 

The ethyl ether of cellulose contains no less than 45% and not more them 50% ethoxy groups. It is available as a free-flowing stable white powder, insoluble in water, glycerol, and other hydrophilic solvents, but soluble in organic solvents such as ethanol, ethylacetate, and chloroform. This cellulose derivative is mainly used as a tablet binder. 

Esters and ethers of cellulose, and especially nitrocellulose, are most widely used in the form of a colloidal solution. This technique is applied in the manufacture of smokeless powder, nitrocellulose varnishes, film and celluloid. 

Taking into consideration both the work of Ostwald, and that of Papkov, extended investigations into the ability of solvents to dissolve esters and ethers of cellulose have been carried out by Moll [53] who has linked the results of his experiments both with the electrostatic constants and with surface tension. The results of Moll s... 

Methylcellulose occurs as a white, fibrous powder or granules. It is the methyl ether of cellulose. It is soluble in water and in a limited number of organic solvent systems. Aqueous solutions of Methylcellulose are surface active, form films upon drying, and undergo a reversible transformation from sol to gel upon heating and cooling, respectively. 

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]. 

In addition to crosslinked resins, insoluble ion exchangers may also be obtained with good results by suitable functionalization of fibers based on cellulose" ° or other materials. In this connection, product 541 is 541 a notable example of a Mannich derivative of the pro-pargylic ether of cellulose." ... 

PROP Ethyl ether of cellulose. White to light tan powder. Sol in some org solvs insol in water, glycerin, and propylene glycol. 

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