Esters cellulosics

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). 

Cellulose acids, cellulose esters, cellulose nitrates, cellulose ethers, cellulose xanthogenates... 

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). 

Phosphorus-Containing Cellulose Esters. Cellulose phosphate [9015-14-9] esters (CP) are of interest because of their inherent dame resistance and ion-exchange capabiUty. 

Clement and Riviere [59] also reported that cellulose acetate or a mixed ester — a nitrate-acetate — can be obtained by reacting cellulose nitrate with acetic anhydride, acetic acid, and sulphuric acid. According to more recent contributions, e.g. Wolfrom, Bower and Maker [60], the reaction should be performed as follows Cellulose nitrate is dissolved in the cold in a little sulphuric add and acetic anhydride, the surplus of acetic anhydride is then hydrolysed also in the cold, and cellulose acetate is extracted with a suitable solvent, such as chloroform. Other methods of acetylating nitrocellulose consist in reduction, for instance with zinc and hydrogen chloride, which entails denitration of the ester, followed by acetylation with acetic anhydride. All these reactions are carried out in the same vessel. Further, it is possible to synthesize mixed esters, cellulose nitrate-acetates, by subjecting cellulose to the action of a mixture that includes nitric acid, acetic add and acetic anhydride in the presence of sulphuric acid (Kruger [61]). The use of a large amount of nitric acid favours the formation of nitrocellulose only. Mixed esters are formed... 

Cellulose esters, Cellulose triacetate, Cellulose nitrate Modified insoluble collagen Polycarbonates, Polyamides, Polysulfonates... 

Cellulose is esterified with certain inorganic acids such as nitric acid, sulfuric acid, and phosphoric acid. A prerequisite is that the acids used can bring about a strong swelling thus penetrating throughout the cellulose structure. The esterification can be considered as a typical equilibrium reaction in which an alcohol and acid react to form ester and water. Of the inorganic esters cellulose nitrate is the only important commercial product. 

Cellulose Esters. Cellulose contains primary and secondary hydroxyl groups. Hence, cellulose esters can be made with all inorganic and organic acids. Traditionally, cellulose esters are made by a controlled acid-catalyzed reaction between an acid or acid anhydride and the hydroxyl groups of cellulose. The reaction requires the absence of water for completion because it is a reversible reaction. The general reaction scheme can be illustrated as shown in Scheme 1. 

PRYM 200 is a very effective stain release agent for poly-ester/cellulosic and 100% cellulosic fabrics. PRYM 200 also inhibits wet-soiling and improves absorbency and antistatic properties of polyester containing fabrics. 

CELLULOSE ACIDS CELLULOSE ESTERS CELLULOSE NITRATES CELLULOSE ETHERS CELLULOSE XANTHOGENATES... 

It is natural that with the growing interest in cellulose acetate, chemists have investigated other organic cellulose esters. Cellulose formate, the ester of the lowest member of the fatty acid series, has been studied. sufficiently to show that it is unlikely to be of commercial im-portance. It is difficult to produce a high degree of esterification of cellulose with this acid, and the ester which is obtained is very limited in solubility, and is highly unstable toward moisture and elevated temperatures. 

Cellulose Homopolysaccharides Hemicelluloses Heteropolysaccharides Crystallinity Cell wall architecture Molecular interactions Cellulose derivatives Cellulose esters Cellulose ethers... 

Acrylates Acrylonitriles Allyl Esters Cellulose esters Epoxies Ethylenic (unsaturated) hydrocarbons Poly-hydroxy esters(eg Pentaerythritol tetramethacrylate,Ethylene Glycol diacrylate) Polyolefins Vinyl compound esters, acids)... 

A recent interesting example of the use of alkane feedstocks to develop more sustainable processes is the direct conversion of ethane into acetic acid developed by Sabic. Acetic acid is the raw material for many key petrochemical intermediates and products, including vinyl acetate monomer (VAM), purified terephthalic acid (PTA), acetate esters, cellulose acetate, acetic anhydride, monochloroacetic acid (MCA), and so on. Acetic acid is produced commercially from several feedstocks and by several different technologies. 

Other important lyotropic cholesteric liquid crystalline polymer are the cellulose esters. Cellulose is a natural polymer. Their chemical formula is shown in Figure 6.24. 

It is required (usually as a condition of warranty) to minimize the rate of hydrolysis of the cellulose acetate ester. Cellulose acetate hydrolysis reduces the useful life of the membrane by increasing the flux and reducing the rejection of the membrane. 

ORIGIN/INDUSTRY SOURCES/USES manufacture of aniline, cellulose esters, cellulose acetate metal polishes soaps shoe polishes refining lubricating oils pyroxylin compound preservative in spray paints perfumes benzidine dyes pesticides rubber chemicals pharmaceuticals (acetaminophen)... 

R. Dicke, A straight way to regioselectively functionalized polysaccharide esters. Cellulose, 11 (2004) 255-263. 

Test for cellulose esters. Cellulose esters respond to the Molisch test for carbohydrates. The sample is dissolved in acetone and treated with 2-3 drops of 2% ethanolic solution of a-naphthol a volume of 2-2.5 ml of concentrated H2SO4 is so added as to form a lower layer. A red to red-brown ring at the interface of the liquids indicates cellulose (glucose). A green ring at the interface indicates nitrocellulose and differentiates it from other cellulose esters. 

---