Cross and Bevan

In 1891, British chemistry Cross and Bevan discovered that wood pulp when treated with sodium hydroxide solution and carbon disulphide, gets converted into cellulose xanthate. When cellulose xanthate is dissolved in caustic soda solution it gives a viscous solution that could be spun to form fibres called Viscose Rayon. Rayon is produced in large scale today in many countries including India. Rayon (also know as viscose) is in fact regenerated cellulose. 

In 1894, Cross and Bevan acetylated cellulose to get cellulose acetate. In 1921, cellulose acetate fibres were marketed for the first time as Celanese. ... 

Hydrated Cellulose, C,2 Hx 0,0 -H2 0, mw 342.30 name proposed by Cross and Bevan for substances recovered from cellulose that has been mercerized (by treatment with aqueous NaOH) and then washed out, or that which has been converted into viscose and then regenerated... 

Cross and Bevan [59] suggested defining the pure cellulose content of a commercial cellulose in terms of its behaviour in the presence of a 17-18% aqueous sodium hydroxide solution. That part of commercial cellulose which is insoluble in this solution bears the name of a-cellulose and is the true cellulose, ft- and y-cellulose remain dissolved in the caustic soda solution. The difference between... 

Cross and Bevan Cellulose- An impure cellulose isolated from the complex it forms with lignin, in materials such as wood straw. The method of isolation is described by Doree (Ref 1) Ott (Ref 2). Cross Bevan cellulose contains both furfural-yielding substances (pentosans), and hexosans of the mannan type. It retains, in the case of coniferous woods, 40-60% of the total furfural-yielding substances in the original wood, and about 55 66% iq the case of hard woods. 

The basic substance is viscose (cellulose xanthate), suggested by C. H. Steam and manufactured by the Cross and Bevan method. 

Cross and Bevan first succeeded in fixing dyes covalently onto cellulose fibers (in 1895) [1], but their multistep process was too complicated for practical application. Early work by Schroter with sulfonyl chloride-based dyes was unsuccessful [2], but Gunther later did succeed in fixing derivatives of isatoic anhydride onto cellulose fibers [3],... 

Fremery and Urban "copper cellulose" 1892 Cross and Bevan viscose process, regenerated cellulose 1894 Cross and Bevan cellulose acetate.)... 

The xanthate is soluble in a dilute solution of sodium hydroxide—a characteristic discovered by Cross and Bevan in 1892—and this property makes the spinning of rayon possible. It is a yellow solid when dissolved in a dilute solution of alkali, it becomes a... 

Although it was known in the years following the discovery by Cross and Bevan that a viscose type of solution could be used in the preparation of regenerated cellulose, the conversion of this solution into useful fibers was not possible until the discovery that the solution required aging until ripe. Ripening is the first part of the actual chemical decomposition of cellulose xanthate, which, if allowed to proceed unhampered, would result in gelation of the viscose solution. 

The steps in the Cross and Bevan reaction may be depicted as follows (Migita and Nakano 1955) ... 

In his introduction to the Lehrbuch, Heuser states objectively Even the methods of treatment adopted by Schwalbe and by Heuser seem to be fundamentally unprofitable, because they do not lead to definite results. These authors have divided the subject along the lines of the various derivatives of cellulose, such as cellulose hydrate, hydrocellulose, oxycellulose, etc. Such discussions are of little value because the substances to which the above names have been applied are not homogeneous chemical individuals, but are mixtures of the most varied degradation products of cellulose and may react very differently under apparently similar conditions. Cross and Bevan have also made the same unfruitful and dangerous mistake of trying to build a system of cellulose chemistry on the basis of such mixtures.. . ... 

It is remarkable that neither of these workers appears to have investigated aqueous preparative methods, despite the fact that Cross and Bevan and their colleagues, from 1892 onward, had been developing the Viscose process for cellulose, and had, in 1907, applied similar reaction-conditions to starch. The formation of a starch viscose imder aqueous conditions was confirmed later by Ost and coworkers, who found that the solution decreased in viscosity on storage ( ripened ), like cellulose Viscose, but with no accompanying separation of starch. Various industrial uses for starch xanthate have since been suggested for example, as a frothing... 

Lignin can be removed by a number of other procedures, but these, in general, result in incomplete delignification or in serious loss or degradation of polysaccharides. The classical procedure of Cross and Bevan employs extraction with 1 % sodium hydroxide, followed by repeated chlorinations and extractions with hot 2 % sodium sulfite solution. The yields of cellulosic material obtained in this procedure are considerably lower than those obtained by the holocellulose procedure. Van Beckum and Ritter showed that hydrolysis of holocellulose with hot 1.3% sulfuric acid for 2 hours yields residues which are equal in amount, and similar in chemical properties, to Cross-and-Bevan cellulose obtained from the same wood. 

The early observation that many of the plant materials purified by the treatments described by Payen were composed of other carbohydrates, led to the rise of the second school of thought concerning the definition of cellulose. - This concept, expressed by Cross and Bevan in many publications, stated that the term cellulose did not denote a... 

By the treatment of Cross and Bevan cellulose, or cellulose isolated by some other purification procedure, with 17.5% sodium hydroxide under carefully controlled conditions, and then carefully washing, a fibrous product is obtained which is termed a-cellulose. As previously indicated, Cross and Bevan used this procedure for determining the purity of cellulose preparations. This product upon further similar treatments continues to lose weight, indicating the empirical nature of the treatment and terminology. Upon acidif3ring the alkaline filtrate a precipitate is formed. This fraction is known as /3-celIulose. The alkali-soluble extract which remains in solution after acidification of the solution is termed -y-cellulose. Since continued extraction of a-cellulose with caustic causes the formation of increasing amounts of /3-and y-cellulose, the incomplete removal of these fractions in one operation or the conversion of o-cellulose into 0- and -y-cellulose is indicated. In practice... 

Holo- cellu- lose Cross and Bevan Cellu- lose Alpha Cellu- lose Solubility ... 

Cross and Bevan cellulose is largely pure cellulose but contains some hemicelluloses. 

The holocellulose, lignin, and pentosans from Ref. 58 are percent extractive-free wood. f Cross and Bevan cellulose is largely pure cellulose but contains some hemicelluloses. 

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