Dissolving cellulose ether

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. 

Mefhyl farmafe is o colorless Flammable liquid with o pleasant ethereal odor. It will dissolve cellulose ethers ond esters but will dissolve them more readily when mixed with other solvent esters or the less volatile halogenated hydrocarbons. 

Methyl propionate has been advocated as a solvent for cellulose derivatives. When it is admixed with other propionates (such as ethyl, propyl, butyl and amyl) the mixture will dissolve cellulose ethers and esters. 

Ethyl hydroxy-isobutyrate is o water-white, stable liquid af a mild odar. and when mixed with other solvents it will also dissolve cellulose ethers, that of ethyl lactate, differing in the fallowing aspects ... 

Cellulosics. CeUulosic adhesives are obtained by modification of cellulose [9004-34-6] (qv) which comes from cotton linters and wood pulp. Cellulose can be nitrated to provide cellulose nitrate [9004-70-0] which is soluble in organic solvents. When cellulose nitrate is dissolved in amyl acetate [628-63-7] for example, a general purpose solvent-based adhesive which is both waterproof and flexible is formed. Cellulose esterification leads to materials such as cellulose acetate [9004-35-7], which has been used as a pressure-sensitive adhesive tape backing. Cellulose can also be ethoxylated, providing hydroxyethylceUulose which is useful as a thickening agent for poly(vinyl acetate) emulsion adhesives. Etherification leads to materials such as methylceUulose [9004-67-5] which are soluble in water and can be modified with glyceral [56-81-5] to produce adhesives used as wallpaper paste (see Cellulose esters Cellulose ethers). 

Sir Joseph Swan, as a result of his quest for carbon fiber for lamp filaments (2), learned how to denitrate nitrocellulose using ammonium sulfide. In 1885 he exhibited the first textiles made from this new artificial sHk, but with carbon fiber being his main theme he failed to foUow up on the textile possibihties. Meanwhile Count Hilaire de Chardoimet (3) was researching the nitrocellulose route and had perfected his first fibers and textiles in time for the Paris Exhibition in 1889. There he got the necessary financial backing for the first Chardoimet silk factory in Besancon in 1890. His process involved treating mulberry leaves with nitric and sulfuric acids to form cellulose nitrate which could be dissolved in ether and alcohol. This collodion solution could be extmded through holes in a spinneret into warm air where solvent evaporation led to the formation of soHd cellulose nitrate filaments. 

As solvents, the amyl alcohols are intermediate between hydrocarbon and the more water-miscible lower alcohol and ketone solvents. Eor example, they are good solvents and diluents for lacquers, hydrolytic fluids, dispersing agents in textile printing inks, industrial cleaning compounds, natural oils such as linseed and castor, synthetic resins such as alkyds, phenoHcs, urea —formaldehyde maleics, and adipates, and naturally occurring gums, such as shellac, paraffin waxes, rosin, and manila. In solvent mixtures they dissolve cellulose acetate, nitrocellulose, and ceUulosic ethers. 

Both the sulfite and alkaline (kraft) methods can be modified to produce high purity chemical ceUulose. These pulps, usuaUy in the form of "dissolving pulps," are not only mosdy free of lignin and hemiceUulose, but the molecular weight of the ceUulose is degraded. This increases solubUity in alkah and provides desired viscosity levels in solution. These dissolving pulps are used to make derivatives such as sodium ceUulose xanthate [9051 -13-2] via alkah ceUulose, and various esters and ethers (see Cellulose esters Cellulose ethers). 

Cyclohexanoae is miscible with methanol, ethanol, acetone, benzene, / -hexane, nitrobenzene, diethyl ether, naphtha, xylene, ethylene glycol, isoamyl acetate, diethylamine, and most organic solvents. This ketone dissolves cellulose nitrate, acetate, and ethers, vinyl resias, raw mbber, waxes, fats, shellac, basic dyes, oils, latex, bitumea, kaure, elemi, and many other organic compounds. 

Of somewhat greater technical interest are the addition compounds and the cellulose esters and ethers. Of the apparent addition compounds the most important is alkali cellulose produced by steeping cellulose in caustic soda and considered to be of general form (CgHioOs), (NaOH) ) rather than a sodium alcoholate compound. Alkali cellulose is a particularly important starting point in the manufacture of cellulose ethers. The ability of aqueous cuprammonium hydroxide solutions to dissolve cellulose appears to be dependent on addition compound formation. 

Fluidized aqueous suspensions of 15% by weight or more of hydroxyethyl-cellulose, hydrophobically modified cellulose ether, hydrophobically modified hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, and polyethylene oxide are prepared by adding the polymer to a concentrated sodium formate solution containing xanthan gum as a stabilizer [278]. The xanthan gum is dissolved in water before sodium formate is added. Then the polymer is added to the solution to form a fluid suspension of the polymers. The polymer suspension can serve as an aqueous concentrate for further use. 

Substituted Cellulose Ethers. Since their introduction for ophthalmic use, MC and other substituted cellulose ethers such as hydroxyethylcellulose, hydroxypropylcel-lulose, hydroxypropyl methylcellulose (HPMC), and carboxymethylcellulose (CMC) have been used in artificial tear formulations.These colloids dissolve in water to produce colorless solutions of varying viscosity. They have the proper optical clarity, a refractive index similar to the cornea, and are nearly inert chemically. Their relative lack of toxicity, their viscous properties, and their beneficial effects on tear film stability have made cellulose ethers useful components of artificial tear preparations. Historically, the most frequently used representative of this group was MC. 

A very frequently described family of polymers subjected to simple coacervation are cellulose derivatives, particularly ethyl cellulose (EC). ° While most cellulose ethers are soluble in water, EC and the cellulose esters are insoluble or only partly soluble in water, e.g., as a function of pH. For coacervation of EC, toluene is a preferred good solvent and cyclohexane a poor solvent. Gradual addition of cyclohexane to a solution of EC desolvates the polymer. Alternatively, EC can be dissolved in hot cyclohexane cooling to room temperature induces polymer phase separation. In both these cases, the coacervate film or droplets can be hardened by exposing the coacervate to a large volume of cyclohexane, whereby physical cross-links are formed. 

Chlorobenzene [108-90-7] is a colorless, neutral liquid with a weak, benzene-like odor. It is insoluble in water and miscible with organic solvents. Chlorobenzene has a good solvency for fats, oils, resins, polymers, binders, rubber, and chlorinated rubber. Cellulose ethers dissolve in the presence of small amounts of alcohols cellulose nitrate is insoluble. Chlorobenzene is a solvent in the production of bitumen and asphalt coatings for building protection. 

Ethanol is a colorless, clear liquid with a characteristic, pleasant odor. It is miscible in all proportions with water and readily miscible with many organic solvents (e.g., ethers, hydrocarbons, acids, esters, ketones, carbon disulfide, glycols, and other alcohols). Ethanol dissolves castor oil, cellulose nitrate with a low nitrate content, polar resins, and polymers. Ethanol in combination with aromatic compounds dissolves cellulose acetate. Mixtures of ethanol, aromatic hydrocarbons, and water are good solvents for some polyamides. Ethanol is extensively used in the chemical and pharmaceutical industries. It is employed as a raw material for many chemical syntheses (e.g., esterification, as an ethylating agent, and reaction medium). Ethanol is an excellent solvent, diluent, and extracting agent for fats, oils, paints, and... 

Butanol [ 71-36-3] (1 -butanol) is a colorless neutral liquid that has a limited miscibility with water and a characteristic odor. It is miscible with organic solvents. Butanol has a high solvency for most known natural and synthetic resins, fats, oils, linseed oil, saturated polyesters, and poly(vinyl acetate). It considerably increases the dilutability of cellulose nitrate solutions with non-solvents. Cellulose esters, cellulose ethers, chlorinated rubber, poly(vinyl chloride), vinyl chloride copolymers, and polystyrene are not dissolved by butanol. 

Benzyl alcohol [100-51-6] is miscible with organic solvents apart from aliphatic hydrocarbons. It dissolves cellulose esters and ethers, fats, oils, alkyd resins, natural and synthetic resins, and colorants. Polymers—with the exception of lower poly(vinyl ethers) and poly(vinyl acetates)—are not dissolved. Small amounts of benzyl alcohol improve the flow and gloss paints, delay the evaporation of other solvent components, and have a plasticizing effect in physically drying paints. It is used in ballpoint pen inks. Benzyl alcohol reduces the viscosity in two-pack epoxy resin systems. 

Isophorone [14.268], [14.269] is an unsaturated cyclic ketone. It consists of a-isophorone [78-59-1] (3,5,5-trimethyl-2-cyclohexen-l-one), which contains about 1-3% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). Isophorone is a stable, water-white liquid with a mild odor that is miscible in all proportions with organic solvents. It dissolves many natural and synthetic resins and polymers, such as poly(vinyl chloride) and vinyl chloride copolymers, poly(vinyI acetate), polyacrylates, polymethacrylates, polystyrene, chlorinated rubber, alkyd resins, saturated and unsaturated polyesters, epoxy resins, cellulose nitrate, cellulose ethers and esters, damar resin (dewaxed), kauri, waxes, fats, oils, phenol-, melamine-, and urea-formaldehyde resins, as well as plant protection agents. However, isophorone does not dissolve polyethylene, polypropylene, polyamides. 

Ethyl acetate [79-20-9] is a colorless, neutral liquid that is partially miscible with water and has a pleasant, fruity odor. It has a good solvency for cellulose nitrate, cellulose ethers, chlorinated rubber, poly(vinyl acetate), vinyl chloride copolymers, polyacrylates, polystyrene, fats, oils, and many natural and synthetic resins (alkyd resins, saturated polyesters, ketone resins). Cellulose acetate is, however, dissolved only in the presence of small amounts of ethanol. Poly(vinyl chloride) is insoluble. 

Isobutyl acetate [110-19-0] is a colorless, neutral liquid with a pleasant, fruity odor. It is miscible with organic solvents, but immiscible with water. Isobutyl acetate has a high solvency for cellulose nitrate, colophony, damar resin, ketone and ketone-formaldehyde resins, maleate resins, urea and melamine resins, and phenolic and alkyd resins. Polymers such as polystyrene, poly(vinyl ethers), poly(vinyl acetate), polyacrylates, chlorinated rubber and vinyl chloride copolymers, as well as fats, greases, and oils are readily dissolved. Postchlorinated poly(vinyl chloride) is less soluble. Polyisobutene, cellulose ethers, polymethacrylates, poly(vinyl butyrals), natural rubber, and manila copal are swollen. Shellac, cellulose acetate, cellulose acetobutyrate, poly(vinyl chloride), and poly(vinyl formal) are insoluble. 

Ethyl triglycol [112-50-5] [2-(2-ethoxyethoxy)ethoxy]ethanol, triethylene glycol monoethyl ether] is an almost colorless, neutral, mild-smelling liquid with a low hygroscopicity. It is soluble in water and most organic solvents, but is only partially miscible with aromatic and aliphatic hydrocarbons. Ethyl triglycol dissolves cellulose nitrate, shellac, colophony, ketone resins, maleate resins, chlorinated rubber, alkyd resins, and many other paint resins. It does not dissolve cellulose acetate, poly(vinyl chloride), vinyl chloride copolymers, fats, oils, and rubber. 

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