Propanediol-water system

If 1 1 complexes are formed (1) in the ground state, then two types of photoreactions will occur parallel to each other, that of the bare and that of the complexed solute, each in its own type of cage. Mixed alcohol/ alkane systems, for example, show an indication of preformed solute-solvent complexes as evidenced by the picosecond experiments of Wang and Eisenthal80 81 on DMABN. Planar model systems like the indolines 3 and 5 (Sec. II.A.l) indicate that an additional channel opens for the B state in alcoholic solvents which increases the nonradiative decay path. This can explain the observed reduction of the fluorescence quantum yield in jirotic solvents about 0.1 in the aprotic polar solvent n-butyl chloride, about 0.01 in 1,2-propanediol, and about 0.001 in water.228... 

In addition to its use in PTT, 1,3-propanediol can replace traditional glycols in urethane-based polymer systems, improving thermal and hydrolytic stability. As a partial substitute for traditional glycols in polyester systems, 1,3-propanediol can improve coating flexibility without affecting other key properties. Other applications include engine coolants and water-based inks (33). 

In contrast to aqueous methods, the polyol approach resulted in the synthesis of metallic nanoparticles protected by surface-adsorbed glycol, thus minimizing the oxidation problem The use of polyol solvent also reduces the hydrolysis problem of ultrafine metal particles, which often occurs in aqueous systems. Oxide nanoparticles can be prepared, however, with the addition of water, which makes the polyol method act more like a sol—gel reaction (forced hydrolysis). For example, 5.5-nm CoFe204 has been prepared by the reaction of ferric chloride and cobalt acetate in 1,2- propanediol with the addition of water and sodium acetate. 

For the water-propanediol system, the number of water molecules coordinated to chromium (III) in each species cannot be taken as six minus the number of coordinated molecules of glycol. This quantity has been determined by considering the dependence of the species concentration upon the solvent composition. The extents of formation of the two species containing one glycol molecule can be expected to show... 

For chromium (III) species in the water-1,3 propanediol system, the statistical correlation of stabilities of species with different compositions involves two adjustable parameters, qi, an intrinsic equilibrium constant for replacement of one water molecule by a glycol molecule (to give a monodentate species) and q2, an intrinsic equilibrium constant for replacement of two water molecules by a glycol molecule (to give a chelate species). Table V presents a correlation of values of QffW for g =... 

HM pectin/sucrose systems Schizophyllan/sorbitol Xanthan/aluminum Xanthan/carob gum mixtures Alginate/calcium Chitosan/acetic acid-water-propanediol... 

Sanz MT, Blanco B, Beltran S, Beltran S, Cabezas JL, Coca J. (2001). Vapor liquid equihbiia of binary and ternary systems with water, 1,3-propanediol, and glycerol. J Chem Eng Data, 46, 635-639. 

Note Liquid preparations are solutions of enzyme in a solvent system consisting of 1,2-propanediol and water. 

Mun, S. Y Lee, H. Vapor-liquid equilibria for the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems. J. Chem. Eng. Data 1999, 44, 1231-1234. 

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