Cellulose alkaline, oxidation

McKelvey etal. (1959) investigated the reaction of epoxides with cellulose in alkaline conditions, reporting that alkaline cellulose reacted readily once the concentration of sodium hydroxide was sufficiently high. However, no evidence was found of reaction between cotton yarn and cellulose with a range of epoxides under a variety of reaction conditions. It was concluded that the apparent reactivity of cellulose with epoxides was primarily due to alkaline swelling of the cellulose, self-polymerization of the epoxide monomers then occurring within the interior structure of the fibres. It was also noted that the reactivity with phenol OH groups was very low (e.g. only 1 % conversion of ethylene oxide with various phenols). 

Vat dyes are insoluble in water and applied to cellulose as dispersions. They are reduced to a water soluble leuco form which has an affinity for cellulose in an alkaline dyebath. Oxidation returns vat dyes to an insoluble form and fixes them to cellulose. Vat dyes are often anthraquinone or indigoid structures. 

While some of the above can occur with cellulose treated with the alkaline earth hydroxides or carbonates, their tendency to insolubilize compounds with carboxyl groups will work against swelling and the increase in accessibility. For example, cellulose oxidized with N204 swells and dissolves in sodium hydroxide but is not soluble in lime solution. 

The methyl ester of oxycellulose, produced by alkaline permanganate oxidation of cuprammonium cellulose followed by treatment with diazomethane, has been reacted with protein by the azide method [34]. Acidic oxyce]]uloses are aiso able to react with alcohols and amines, including proteins, to form esters or amide derivatives. 

Low-substituted hydroxypropyl cellulose is manufactured by reacting alkaline cellulose with propylene oxide at elevated temperature. Following the reaction, the product is recrystallized by neutralization, washed, and milled. 

In 1873, it was first reported that cellulose that has been oxidized with chromic acid or potassium permanganate is weakened in alkaline solutions, and several years later these findings were confirmed. By 1899, it was known that cellulose that had been oxidized with nitric acid, or bromine in the presence of calcium carbonate, afforded oxidized celluloses from which D-glucoisosaccharinates were formed on suitable treatment with lime-water.Hydrocelluloses, alkaline-hypobromite oxycelluloses, and alkaline-hypochlorite oxycelluloses have no internal, alkali-sensitive links. Cellulose oxidized with neutral hypochlorite, acidic hypochlorite, potassium dichromate and sulfuric acid, potassium dichromate and oxalic acid, periodic acid, or metaperiodate gives products which are alkali-sensitive. Periodic acid oxycellulose and metaperiodate oxycellulose are much more alkali-sensitive than the others. ... 

Cellulose, oxidized with nitric acid, yields isosaccharinates and dihy-droxybutanoates when the product is treated with lime-water. Cellulose which has been oxidized with acidic potassium permanganate solution contains some uronic acid groups, and, when placed in dilute alkaline solutions, forms chains with a degree of polymerization (D. P.) of about 90. In more concentrated alkaline solutions, the chains are shortened more, and have a D. P. of about 35. 

No dialdehyde groups are detectable in modified celluloses obtained by oxidation of cellulose with persulfate, hypobromite, hypochlorite, permanganate, nitric acid, or dichromate. " Alkaline-hypochlorite oxidized starches, which have already been partially degraded by alkali, are more resistant to alkaline degradation than are unmodified starches, and the alkali-lability slowly decreases with increasing oxidation because of the resulting oxidation of reducing ends."... 

Alkaline Hypochlorite Oxidation of Cellulose Analogs, M. L. Wolfrom and W. E. Lucke, Tappi, 47, 189-192 (1964). 

In alkaline solutions, oxidation produces celluloses with a high content of carboxylic groups, but the hemiacetal end group is not oxidized to an appreciable extent. 

Prepared by etherification of alkaline cellulose with ethylene oxide. Commercial samples have MS values of 1.8 - 3.5. Worldwide production in 1987 38,500 t. Thickener, binder, stabiliser and suspending agent with widespread uses in the paint, oil and polymer industries. 

Poly (2-hydroxypropyl. Me) ether Hydro-xypropyl methyl cellulose. HPMC. E463. Hypromellose, USAN. Hydroxypropyl-methylcellulose, JAN. Cellulose hydro-xypropyl methyl ether, BAN, INN [9(X)4-65-3] Prepared by etherification of alkaline cellulose with methyl chloride and propylene oxide. Commercial samples have methyl DS values of 1.1-2.0 and hydroxypropyl MS values of 0.1 - 1.0. Thickening and binding agent with widespread industrial uses in adhesives, building products, films, protective creams and colloids. Approved for food use in US and EU. Used in deep fried batters. Shows better water solubility and electrolyte tolerance than methylcellulose. Component of artificial tears. 

Made from alkaline cellulose by etherification with methyl chloride and butylene oxide either stepwise or... 

Desizing by chemical decomposition is applicable to starch-based sizes. Since starch and its hydrophilic derivatives are soluble in water, it might be assumed that a simple alkaline rinse with surfactant would be sufficient to effect removal from the fibre. As is also the case with some other size polymers, however, once the starch solution has dried to a film on the fibre surface it is much more difficult to effect rehydration and dissolution. Thus controlled chemical degradation is required to disintegrate and solubilise the size film without damaging the cellulosic fibre. Enzymatic, oxidative and hydrolytic degradation methods can be used. 

The stripping of cellulosic materials dyed with reactive dyes is carried out by alkaline reduction followed by hypochlorite oxidation, preceded by a boiling treatment with EDTA if metal-containing dyes have been used. For example, a treatment with 5 gA sodium carbonate or sodium hydroxide and 5g/l sodium dithionite at the boil is followed by a treatment in 0.5-1 °Tw hypochlorite, an antichlor and thorough rinsing. 

Brown et al.68 have developed a cellulose plate with a fluorescent indicator. Compounds are developed in 3.0% (w/v) NHfc.Cl and detected by fluorescence quenching. These authors also use 0.5% mercaptoethanol in their mobile phase, but this is only to prevent oxidation of the labile reduced pteridines, which are not adequately protected by substitution at the N5 position. Since neutral or alkaline solutions of leucovorin are relatively stable in air, this precaution may not be required for routine assay. 

The vat dyes section of the Colour Index incorporates a subgroup called solubilised vat dyes. These are sodium salts of sulphuric acid esters of the parent leuco vat dyes, such as Cl Solubilised Vat Blue 6 (1.50). In contrast to the leuco compounds, the vat leuco esters dissolve readily in water at neutral pH. They have relatively low substantivity for cellulose and thus have been used mainly in continuous dyeing and printing. In the presence of an oxidant in mineral acid solution (sodium nitrite and sulphuric acid, for example) the leuco ester is rapidly decomposed and the insoluble vat dye regenerated. Thus application of a vat leuco ester represents a simpler (but more costly and less versatile) alternative to conventional dyeing methods via the alkaline leuco compound. 

In more recent times Juettner [18] has worked extensively on the oxidation of various types of coal, including charcoal. He examined the action of various oxidizing agents such as potassium permanganate in an alkaline medium and nitric acid. On such oxidation of the charcoal obtained by carbonization of cellulose at 1000°C mellitic acid in a yield of 25 % by weight resulted. 

Nitrotoluenes, Van No strand, NY(1918) 2)M.Kostevitch, "Tarry Matter of Alpha Trinitrotoluene, Part II, Imprd Art Vol-taire,P aris( 1927), 8 3)Sidgwick( 19 37), 259 et seq 4)Davis(1943), 136-7, 147, 149-51 170-1 5>negering( 1950), 139 seq 6) Dept of the Army TM 9-1910( 1955), 146 Alkalies, Action on Nitric Esters. Organic nitrates in general are readily saponified by alkaline solns. A simple metathetical reaction to yield the alkali nitrate and alcohol does not take place instead, as a result of simultaneous oxidation and reduction, alkali nitrite and a variety of products are formed depending on the conditions of the reaction. The resistance of different nitric esters to alkalies varies considerably. Thus, starch nitrate is decomposed much more slowly than cellulose nitrate and amylopectin nitrate still more alowly... 

Anthraquinone vat dyes are water-insoluble dyes. They arc converted til leuco compounds (anthrahydroquinone.s) by reducing agents such as sodium hydrosulfite in alkaline conditions. These water-soluble leuco compounds have an affinity to cellulose fibers and penetrate them. After reoxidation by means of air or other oxidizing agents, the dye becomes water-insoluble again and fixes firmly on the fiber. 

Table I shows that aliphatic products in reaction liquors from both alkaline nitrobenzene and nitric acid oxidations have been largely neglected. The oligosaccharides listed were isolated from reaction of regenerated cellulose with oxygen under alkaline conditions. Table II lists references to the aromatic products isolated from the same three types of oxidations.

---