Oxidation of cashew tree gum exudate polysaccharide with TEMPO reagent

• Autor(a) principal: Cunha,Pablyana L. R.
• Data de Publicação: 2007
• Outros Autores: Maciel,Jeanny S., Sierakowski,Maria Rita, Paula,Regina C. M. de, Feitosa,Judith P. A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532007000100009
• topic: cashew gum; oxidation; TEMPO; Anacardium occidentale; polysaccharide

Cashew gum (CG), an exudate polysaccharide from Anacardium ocidentale trees, was oxidized with TEMPO reagent and the 7product (CGOX) characterized by spectroscopic techniques (FT-IR and NMR), chromatographic analyses (HPLC and GPC), viscosity measurements and thermal analysis (TGA). The yield of the reaction product was 96%. The uronic acid content in starting gum (7.2 m%) was increased to 36 m%. The degree of oxidation based on free galactose and glucose units was 68%. NMR data show that oxidation occurred preferentially at primary carbons of galactose units. High degradation degree after oxidation was estimated by the difference on the expected and observed etaCGOX/etaCG ratio. The presence of organic and inorganic impurities in the new polyelectrolyte was detected by TGA. A less thermally stable cashew gum is formed after the oxidation with TEMPO based on initial decomposition temperature and IPDT.