6214-01-3Relevant articles and documents
Formation and characterisation of a physical chitin gel
Vachoud, Laurent,Zydowicz, Nathalie,Domard, Alain
, p. 169 - 177 (1997)
The formation of N-acetyl chitosan gels in anacetic acid-water-propanediol solution was studied. Side reactions arising from the esterification of 1,2-propanediol by acetic anhydride, and hydrolysis of acetic anhydride were studied, as well as their possible role on the gel formation. The gels were studied by FTIR and 1H NMR spectroscopy. Independently of the initial acetylation degree of chitosan, a minimal acetylation degree is required for gelation (80%). The final acetylation degree of the gels increases with the molar ratio acetic anhydride/amine, but does not reach 100%. An increase in temperature favours the molecular mobility, inter- and intra-molecular hydrogen bondings and hydrophobic interactions, responsible for gelation which appears to depend on two parameters: a critical acetylation degree and a critical molecular weight allowing the aggregation of the polymer chains. The nature of the solvent used to avoid chitosan side reactions during gelation (ethanol or propanediol) does not influence the chemical structure of the gel but only the kinetics of gelation.
Homogeneous and silica-supported zinc complexes for the synthesis of propylene carbonate from propane-1,2-diol and carbon dioxide
Comerford, James W.,Hart, Sam J.,North, Michael,Whitwood, Adrian C.
, p. 4824 - 4831 (2016/07/11)
Three organozinc complexes have been synthesised and found to catalyse the carbonylation of propylene glycol with carbon dioxide to form propylene carbonate. A similar tethered organozinc complex was supported onto high loading aminopropyl functionalised hexagonal mesoporous silica and was also found to be catalytically active.
Regio- and stereoselective transacylation of polyhydric alcohols using pronase in organic solvents
Bhattacharya, A,Ali, E
, p. 898 - 899 (2007/10/02)
Pronase a mixture of proteases from Streptomyces griseus has been found to be a good catalyst for transacylation in organic solvents.With equimolar concentrations of p-nitrophenyl acetate as acyl donor in pyridine, aliphatic diols give predominantly the monoacetates.Glucose and isomeric hexoses give the 6-O-acetates in good yield. 6-Deoxy-sugars however, yield mixtures of acetates indicating that regioselectivity among the secondary hydroxyl groups are poor.Racemic trans-1,2-cyclohexanediol affords the (1R, 2R)-monoacetate in 44percent yield with greater than 90percent enantiomer ic purity. cis-1,2-cyclohexanediol and cis-1,2-cyclohexanedimethanol also give optically active monoacetates.