Polar dissolvent dimethylformamide

The Japanese researchers report [ 175-179] on the syntheses of aromatic polysulfones via the method of polycondensation in the environment of polar dissolvent (dimethylformamide, dimethylacetamide, and dimethylsulfoxide) at 60-400 °C in the presence of alkali metal carbonates within 10 min to 100 h. The s mthesized thermoplastic polysulfones possess good melt fluidity [175]. 

Polyestersulfoneketones have been produced be means of electrophyl-ic Friedel-Crafts acylation in the presence of dimethylformamides and anhydrous AICI3 in enviromnent of 1,2-dichlorethane on the basis of simple 2- and 3-methylbisphenyl esters and 4,4 -bis(4-chloroformylpheoxy) bisphenylsulfone. The copolymer has the molecular weight of 57,000-71,000, its temperatures of glassing and decomposition are 160.5-167,0 C and > 450 °C, respectively, the coke end is 52-57% (N2). Copolyestersul-foneketones are well soluble in chloroform and polar dissolvents (dimethylformamide and others) and form transparent and elastic films [426]. 

Allyl thiocyanate isomerizes at similar rates in toluene, nitrobenzene, dimethylformamide, cyclohexane, and acetonitrile The reaction is slowest in the two most polar solvents, dimethylformamide and acetonitrile, and its rate is not appreciably affected by dissolved potassium thiocyanate. 

The solvent. The solvent should be chosen to best dissolve the sample, to be compatible with the column packing and to permit detection. The most commonly used eluents in SEC are tetrahydrofuran (for polymers that dissolve at room temperature), <9-dichlorobenzene and trichlorobenzene at 130 C and 150°C (for crystalline polyolefins) and phenolic solvents at 100 C (for condensation polymers, such as polyamides and polyesters). For the more polar polymers, dimethylformamide and aqueous eluents may be employed, but care is required in avoiding interactions between the polymer (sample) and the gel (packing). Flow rates of 1 ml/min are typical for SEC analysis. 

The drugs in water or N,2V-dimethylformamide appear to enter SC by partitioning according to their relative solubilities. The ionized salt is more soluble than the base in water therefore, the base moves out of water and enters SC more readily than the salt does. N,]V-Dimethyl-formamide is less polar than water. It therefore dissolves the base more readily than water, and the base moves less readily out of the solvent or into SC. 

Polymerization conducted in aqueous interfaeial systems suffers from hydrolytic decomposition. The decomposition reaction can be minimized when contact with water is avoided. In the case of polymerization in nonaqueous interfacial environments, products with number average molecular weights up to 5000 can be obtained. Various aromatic polymers were prepared from the reaction of equimolar amounts of the acid dissolved in an aqueous base and the corresponding diacid chloride dissolved in an organic solvent. Reaction occurred between dibasic acid in one phase and an acid chloride in the other. Polar solvents for this reaction include dimethylformamide and 1,4-dicya-nobutane. 

There are various options to overcome the reagent incompatibility problem. One way is to use a solvent or a solvent combination capable of dissolving both the organic compound and the inorganic salt. Polar, aprotic solvents, such as dimethylsulphoxide (DMSO), dimethylformamide (DMF) and tetrahydrofuran (THF), are sometimes useful for this purpose but many of these are unsuitable for large-scale work due to toxicity and/or difficulties in removing them by low vacuum evaporation. 

PVDF parts can be welded using a PVDF powder base bonding agent, dissolved in a polar solvent such as dimethylformamide. This technique, which at first sight appears easy to apply, nevertheless has certain disadvantages. 

The autoxidation of simple thiols is also very dependent on the basicity of the solvent and high polar solvents such as dimethylformamide [108— 110] and tetramethylguanidine [108] accelerate the reaction. The first detailed investigation was carried out with the thiols dissolved in aqueous sodium hydroxide solution [111]. Although the apparatus was crude, stoichiometric conversion to the disulphide was observed with the ease of oxidation of different thiols decreasing in the order n-propyl > n-butyl > n-amyl > benzyl > phenyl. 

The compound Pd(bpy)Cl2 is obtained as fine light orange needles. It is insoluble in water and organic solvents, but soluble (with solvolysis) in polar solvents such as dimethyl sulfoxide (DMSO) and Af,N-dimethylformamide (DMF). It dissolves in 2 M sodium hydroxide solution with hydrolysis of the chloro groups. The Pd—Cl stretching vibrations occur at 340 and 347 cm ... 

Water is the most common solvent system used for polarography but many other solvents such as dimethylformamide (DMF), acetonitrile, dimethyl sulphoxide (DMSO) are also widely used. In general polar solvents must be used as they must be able to dissolve a suitable ionic salt, such as tetraalkylammonium salts, to act as a supporting electrolyte. The effect of the solvent is often profound as it greatly affects the stability of electrolytic intermediates. The biggest contra.st is between protic solvents such as water and the alcohols which readily supply hydrogen ions and the aprotic solvents which do not. 

Because polyurethane is a polar material, it is resistant to nonpolar organic fluids such as oils, fuels, and greases, but it will be readily attacked and even dissolved by polar organic fluids such as dimethylformamide and dimethyl sulfoxide. 

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