Mercerization intermediates

Dinsmore and Mercer further investigated this reaction using DBU as a base and n-Bu3P/DBAD (di-tert-butyl azodicarboxylate) as Mitsunobu s reactants, and found an unexpected steroselectivity in the Mitsunobu transformation [75b], In fact, the stereochemical course of the Mitsunobu reaction (Scheme 6.11) depended on whether the carbamic acid intermediate was N-substituted with hydrogen (retention) or with carbon (inversion). 

Alkali celluloses are extremely important intermediates because they exhibit a markedly enhanced reactivity compared with original cellulose. The reagents can penetrate more easily into the swollen cellulose structure and thus react with the hydroxyl groups. For instance, preparation of alkali cellulose, named mercerization after its inventor John Mercer (1844), is an important step when producing cellulose xanthate, from which viscose fibers and cellophane are prepared. 

Sarko, A., Nishimura, H., and Okano, T., Crystalline alkali-cellulose complexes as intermediates during mercerization, in The Structures of Cellulose, Atalla, R.H., Ed., ACS Symposium Series, No. 340, American Chemical Society, Washington, D.C., 1987, p. 169. 

Strong alkali solutions acting on cellulose (at room temperatures) produce alkali cellulose. The studies on the structure of alkali cellulose [43] obtained with 20-40% NaOH solutions indicated that the substance is not a true alcoholate but an addition complex, RceiiOH NaOH. A true alcoholate can be obtained, for example, from dry cellulose and Na in liquid ammonia. Alkali cellulose has a large range of applications as an intermediate product in the preparation of cellulose ethers, and xanthate (dithiocarbonate), as well as in cellulose mercerization. 

Fogel M, Lifschitz-Mercer B, Moll R, et al. Heterogeneity of intermediate filament expression in human testicular seminomas. Differentiation. 1990 45 242-249. 

Crystalline Alkali-Cellulose Complexes as Intermediates During Mercerization... 

II allomorph is known by the term regenerated cellulose. Regeneration involves either preparing a solution of cellulose in an appropriate solvent or of an intermediate derivative followed by coagulation and recrystallization. This process is used to produce rayon fibers. Mercerization involves intracrystalline swelling of cellulose in concentrated aqueous sodium hydroxide (NaOH), followed by washing and recrystallization. This process is used to improve the properties of natural yams and fabrics. The transition from cellulose I to cellulose II is not reversible, and fliis implies that cellulose II is a stable form as compared with the metastable cellulose I. 

T. Okano and A. Sarko, Mercerization of eellulose. II. Alkali-cellulose intermediates and a possible mercerization meehanism, J. Appl. Polym. Sci, 30 (1985) 325-332. 

Okano,T. and Sarko, A. (1985) Mercerization of ceUulose. II. AlkaU-ceUulose intermediates and a possible mercerization mechanism. Journal of Applied Polymer Science, 30,325-332. 

Mellor traced this idea of association of molecules by residual affinities to Mercer and Playfair it was adopted by H. E. Armstrong, and J. W. Walker. The idea of an intermediate complex appears in the work of W. Higgins (1789 see Vol. HI, p. 745) and in Dalton s note-books. Kekule s scheme of reaction (3) implies the modern theory of the intermediate complex , since he said ... 

The intermediate compound theory of catalysis was extended and clarified by Mercer and Playfair. ... 

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