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Chitin xanthate and some xanthate ester derivatives

1994; Elsevier BV; Volume: 256; Issue: 2 Linguagem: Inglês

10.1016/0008-6215(94)84218-3

1873-426X

Shigehiro Hirano, Akihiro Usutani, Min Zhang,

Nanocomposite Films for Food Packaging

A viscous orange-red aqueous solution of @(sodium thiojthiocarbonyl cellulose (sodium cellulose xanthate) is well known as “viscose”, which is an intermediate for the manufacture of rayon and cellophane [l-3]. 0-(Sodium thiojthiocarbonyl starch (sodium starch xanthate) is also known [4]. Chitin and chitosan structurally resemble cellulose and are widely distributed as the main structural components in cuticles of crustaceans, insects, and mollusks, and in cell walls of microorganisms. Noguchi et al. [5] first reported 0-(sodium thiojthiocarbonyl chitin [sodium chitin xanthate (2) (Fig. l)] without detailed analytical data and attempted to use it for the preparation of chitin fibers and for a composite with cellulose. Since then, almost no studies have dealt with 2 and its derivatives. Compound 2 is a key intermediate for the preparation of novel composites or blended materials with other organic and inorganic compounds. For analysis of the chemical structure of 2, which is quite unstable, it is desirable to convert it into stable derivatives. We now report the preparation and structural analysis of 2 by preparing its 0-(benzylthiojthiocarbonyl and 0-(alkylthiojthiocarbonyl derivatives. In earlier methods [6-lo] for the preparation of “alkaline chitin” (11, natural chitin was treated repeatedly with concentrated NaOH, resulting in an inefficient use of the alkaline solution. Recently, we found that N-acetylchitosan xerogel (a regenerated chitin) [11,12] was an excellent starting material for the preparation of 1 (alkaline N-acetylchitosan), because the xerogel has intramolecular hydrogen bonds weaker than natural chitin, resulting in easy solubilization into 14% aq NaOH, with little waste of the concentrated alkaline solution. Compound 1, in 14% aq NaOH, was treated with carbon disulfide (40 mol equiv NAc) to afford a viscous orange-red solution of 2, which was unstable in EtOH, in MeOH, and in aq acetic acid, giving N-acetylchitosan. The chemical structure of 2