Amylose pyridine with

Although this article is primarily concerned with gas-liquid chromatography of simple carbohydrates, it is worth noting that certain polysaccharides have been trimethylsilylated. Thus, chlorotrimethyl-silane in pyridine yielded fully trimethylsilylated amylose, cellulose, and pullulan, but failed with dextran and amylopectin.196 Cellulose, amylose, and polyvinyl alcohol have also been trimethylsilylated in molten N-(trimethylsilyl)acetamide.197 As examples of a new class of... 

Amylose [9005-82-7] (CgHjoOsln (for use in iodine complex formation). Amylopectin was removed from impure amylose by dispersing in aqueous 15% pyridine at 80-90 (concn 0.6-0.7%) and leaving the soln stand at 44-45" for 7 days. The ppte was re-dispersed and recrystd during 5 days. After a further dispersion in 15% pyridine, it was cooled to 45°, allowed to stand at this temperature for 12hours, then cooled to 25° and left for a further lOhours. The combined ppte was dispersed in warm water, ppted with EtOH, washed with absolute EtOH, and vacuum dried [Foster and Paschall JACS 75 1181 7955]. 

Common starch esters include the acetates. High d.s. starch acetates have been formed by using acetic anhydride with either sodium acetate or pyridine catalysts at 90-100 °C [158,159,160]. The major use of starch acetates have been in the study of the stmctures of amylose and amylopectin after acid hydrolysis. Acetylation of granular starch in aqueous suspension by acetic anhydride at pH 10-11 is used to produce low d.s. starch acetates that are primarily used for the stabilization of their viscosity and for their water-soluble clarity. The acetylation decreases the hydrophilic character and increases the hydrophobic character of starch. The major uses of starch acetates is in the paper industry for surface sizing to give improved print quality, uniform porosity, surface strength, and resistance to various solvents [161]. 

The derivatives are formed by reacting the polysaccharides with the substituted isocyanates in pyridine and the desired material is isolated as the methanol-insoluble fraction. Prior to coating, the silica particles are treated with 3 -aminopropyltriethoxysilane using the standard procedure. The polysaccharides derivatives are then dissolved in tetrahydrofuran and adsorbed on the aminopropylsilica. The stationary phase loading should be about 25% w/w. The derivatized cellulose and amylose have been used extensively in the separation of chiral drugs of all types. 

Synthesis of cellulose and amylose cyclohexyl carbamates was performed with a similar process amylose derivative was prepared by dissolving amylose (1 g) in A,Af-dimethylacetamide (10 ml), containing LiCl (1 g), at 80°C for 24 h then, an excess of cyclohexyl isocyanate (3.3 g, 26 mmol) and 20 ml pyridine were added to the amylose solution. The reaction was continued at 80°C for 24 h. 

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