Organic solvents, swelling ratio

Table I. Swelling of Four Pyridine-Extracted Coals with a Series of Organic Solvents Ratio of Weight of Swollen Coal at Equilibrium to...

The swelling/shrinking starts if thermodynamically conditions for a volume phase transition, e.g., temperature, pH, appropriate mixing ratio of water with a hydrophobic agent, like an organic solvent, are given. 

However, up to now no subsequent modification of the 2-0-acetyl starch is known. We have found that the 2-0-acetyl starch samples are not soluble in common organic solvents but they swell to a certain extend. Heterogeneous conversions of 2-0-acetyl starch swollen in DMA with Tos-C1/N(C2Hs)3 leads to a small DSt< only (Tab. 3). On the other hand, 2-0-acetyl starch can be dissolved in DMA in combination with LiCl which is an appropriate reaction medium for tosylation as discussed for unmodified starch in detail above. As shown in Tab. 3, the homogeneous procedure in DMA/LiCl is suitable to prepare products of high DStos- At a molar ratio Tos-Cl modified AGU of 2 1 respectively 5 1 using a 2-0-acetyl starch with DSac = 0.7 a DSto of 0.53 respectively 1.37 is reached. From C-NMR )ectroscopy a preferred tosylation of 0-6 can be concluded. 

Three other chiral polymers have been synthesised by copolymerization of the chiral monomer 126 with styrene in the presence or not of crosslinking agent (Scheme 66). Chiral polymer 133 was prepared by suspension copolymerization of aminoalcohol 125 with styrene and DVB in a 1/7/2 molar ratio. Polymer 133 swelled well in organic solvents such as toluene, benzene and THF and that unusual swellability could be due to the bulkyness and polarity of the chiral monomer 125. The replacement of DVB by 127 as the crosslinking agent afforded chiral polymer 134 after copolymerization. This one also swelled well in... 

Organic solvents cause a shift in the ratio of saturated to unsaturated fatty acids. " In a solvent-tolerant strain, an increase in the saturation degree has been observed during adaptation to the presence of toluene. Solvent-tolerant strains also have the ability to synthesize tran -unsaturated fatty acids from the m-form in response to the presence of organic sol-vents. Increases in the saturation degree and the ratio of trans-(orm change the fluidity of the membrane and the swelling effects caused by solvents are depressed. 

Cellulose is soluble or partially soluble in mixtures of nitrogen dioxide with certain organic solvents (Shon gin Khait, 1937). High mole ratios of nitrogen dioxide to cellulose during an oxidation reaction can partially swell the cellulose fibrils. Upon removal of the oxidant, the fibrils fuse together producing stiff oxidized fabric. 

Magnesium alumimun silicate is insoluble in water or alcohol, but swells to many times its original volume to form colloidal dispersions. It is practically insoluble in organic solvents. Dispersions in water at the 1% to 2% level are thin colloidal dispersions. At 3% or above the dispersions are opaque, and as the concentration is increased above 3% the viscosity of the dispersions increases rapidly and exhibits thixotropic behavior. Magnesium aluminum silicate forms a gel at levels of 10% and above. Several different grades are available differentiated by Al Mg ratio (montmorillonite saponite ratio), particle size, dispersion viscosity, and degree of chemical activity. 

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