Amylose acetates

Peterlin168 has shown that the viscometric data for potato amylose acetate in chloroform solution can be readily interpreted in terms of a random-coil model for the molecule, in which there is hindered rotation at the oxygen atom of the glucosidic linkage. 

Dombrow and Beckmann163 have carried out ultracentrifugal and viscometric studies of several amylose acetates in methyl acetate solution. Their data, shown in Table VI, were interpreted as supporting the idea of a helical configuration in solution. 

Ultracentrifugal and Viscometric Data for Amylose Acetates in Methyl Acetate Solution... 

Senti and Witnauer206 have reported studies on the fiber diagrams from various alkali-amyloses. Specimens were obtained by deacetylating clamped specimens of amylose acetate with the appropriate alkali. The positions of the alkali ions and the lateral packing of the amylose chains were determined with the aid of Patterson projections. In the A - and B -modifica-tions, the fiber period was 22.6 A. (extension of 6 D-glucose units), whilst in the V -modification it was 8.0 A. These authors have also studied in detail the addition compounds of amylose and inorganic salts with special reference to the structure of the potassium bromide-amylose compound.206 Oriented alkali fibers were treated with the appropriate salt solution. Stoichiometric compounds were formed. The x-ray patterns from these showed that the addition compounds with potassium salts crystallized in... 

Cnossen and co-workers measured tf of rhB on an aluminum mirror covered with amylose-acetate ester of a various thickness (1 to 6 nm) [114]. They found Eq. (1) to agree well with the experimental observations ... 

Schoondorp, M. A., Schouten, A. J., Hulshof, J. B. E., Feringa, B. L., and Oosteigetal, G. J. Langmuir-Blodgett Films of Amylose Acetal Dye Mixtures. 1. Monolayer Behaviour of Mixtures of Amylose Acetate and a Chiral p-Nitroazobis(benzene) Dye. Langmuir 8, 181 ... 

Physicochemical studies of other aliphatic, carboxylic esters of polysaccharides include (a) assessment of the gel-permeation properties of the series cellulose propionate-cellulose heptanoate, (b) dissolution of cellulose acetate phthalate, (c) monolayer properties of amylose acetate, and (d) melting and transition temperatures of the series amylose acetate-amylose hexanoate. Amylose acetate assumes a helical conformation at air-water interfaces and in oriented films, and the X-ray-analysis data for mannan acetate imply a threefold screw-axis... 

He was always a strong promoter of new uses for agrieultural erops and produets from them guar gum, hemieelluloses, and, in later years, banana stareh, along with compounds such as amylose acetate and 5-thio-D-glueose. 

A. Richter and W. Wagenknecht, Synthesis of amylose acetates and amylose sulfates with high structural uniformity, Carbohydr. Res., 338 (2003) 1397-1401. 

Amyloses.—Various parameters and techniques have been used to define the morphology of amylose acetates. Chemical modification of maltotriose has been reported.Periodate-oxidized and reduced (sodium borohydride) amylose has been used as the substrate in an assay of a-amylase. The susceptibility of amylose-Cibachron Blue 3G-A to a-amylase and the use of this dyed amylose derivative in assays of a-amylase have been discussed. ... 

A combination of stereochemical structural refinement and. T-ray diffraction analysis has been used to determine the crystal stracture of potassium hydroxide-complexed amylose, obtained by heterogeneous deacetylation of amylose acetate. The complex crystallizes as an orthorhombic unit cell with p2,2,2 symmetry and dimensions a = 8.84,6 = 12.31, and c = 22.41 A. The conformation of the amylose chain is a distorted left-hand helix with six o-glucose residues per turn. Each three-residue asymmetric unit is complexed with one molecule of potassium hydroxide and three molecules of water. Extension of the amylose chain probably arises because of the co-ordination of the K ion. 

Amyloses.—The diffusion of helium, oxygen, nitrogen, and carbon dioxide in amylose acetate has been studied in the temperature range 30—60 Arrhenius parameters were evaluated and the solubility of the gases in the polymer discussed in terms of the condensing tendency of the gases studied. 

A study has been made of the thermal stability of amylose and some of its derivatives, viz., amylose palmitate, amylose succinate, and sodium carboxy-methylamylose. Results indicated that except for amylose succinate, esterification increased the thermal stability of all the amylosic derivatives compared to amylose. The order of stability noted was amylose palmitate > amylose acetate > amylose propionate > amylose > sodium carboxymethyl-amylose > amylose succinate. 

Table 1. Partial specific volume of amylose acetate. ...

Table 1. Second virial coefficient of amylose acetate.

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