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A method is proposed for the determination of anhydride groups by their reaction with piperidine in acetonitrile. This method exhibits some advantages over those known previously, which are determined by the use of a more basic amine as the amide-forming agent and of acetonitrile, which is indifferent to anhydride groups and miscible with water, as solvent. It is demonstrated that solvents that were previously used for the determination of anhydrides are not indifferent to the latter. This method provides the titrimetric determination of strong acids. © 1998 MAHK Hayka/Interperiodica Publishing.

The formation of molecular complexes of maleic anhydride with some substituted imidazoles in acetonitrile, dimethylformamide, and dimethyl sulfoxide was studied. The selection of 2-methylimidazole as a reagent for the photometric determination of maleic anhydride in the dimethyl sulfoxide medium was substantiated using kinetic and spectrometric techniques.

The reaction of esterification by maleic anhydride in methyl ethyl ketone in the presence of triethylamine is proposed for the determination of alcohol hydroxyl groups. The equivalent amount of maleic anhydride that entered into the reaction is determined spectrophotometrically by the reaction with 2-methylimidazole. In the determination of hydroxyl groups in epoxy-dian resins, maleic anhydride is determined by the potentiometric titration with alkali after hydrolysis with water by the first potential jump.

A procedure is developed for the determination of maleic anhydride in the presence of endic anhydride by potentiometric titration in aqueous-organic solutions. It is found that separate titration of a hydrolyzed mixture of anhydrides is most efficient in the system acetonitrile-water (3:2).

A procedure is developed for the determination of maleic anhydride in maleinized adducts based on natural oils by the reaction yielding molecular complexes of 2-methylimidazole and maleic anhydride in dimethyl sulfoxide. The procedure can be used for the determination of maleic anhydride in polymers based on a mixture of anhydrides in the presence of acid.

A reaction of maleic anhydride with epoxy-dian resins in methyl ethyl ketene was investigated. It was shown by potentiometric titration that the resulting maleic esters are stable to hydrolysis in acid and weakly acid organic solutions. This reaction can be used for the quantitative determination of hydroxyl groups in epoxy resins. Epoxy groups do not interfere with the formation of maleic esters under the conditions of determination. The optimal reaction conditions were found. The reaction kinetic was investigated, the reaction rate constants were determined at various temperatures, and the activation energy was found. The value of the activation energy indicates that the reaction is characterized by a low potential barrier. © 2001 MAIK "Nauka/Interperiodica".

Reaction of epoxy-diane resin with complex based on monoamide of phosphonic acid and ammonium chloride (MODAF) is studied. It is established that the MODAF equivalent in the reaction with epoxy resin is equal to 1/5 of its molecular weight. Epoxy resin is cured via the reactions of both monoamide and ammonium chloride. The dependence of the epoxide and hydroxyl groups has a stepped character over time, which is probably due to the existence of certain threshold concentrations of the curing coefficients. The investigated reaction is a new example of macroscopic coherence manifestation. © 2010 Pleiades Publishing, Ltd.

The optical and protolytic properties of 2,4,6-tris[(dimethylamino)methyl] phenol were studied. The use of nonaqueous solvents provides the determination of the ratio of functional groups by potentiometric titration. A procedure is proposed for the determination of the functional composition of the compounds.

Analytical reactions for the determination of epoxy and isocyanate groups in the presence of each other in epoxy-isocyanate compositions were studied. For the determination of epoxy groups in the presence of isocyanate groups, a test with HBr in glacial acetic acid was proposed; acetic acid reacts with isocyanate groups and, hence, masks them. Isocyanate groups in the presence of epoxy groups were determined by potentiometric titration with a solution of piperidine in ethyl methyl ketone. The addition of toluene to the test solution decreases the fraction of the enol form of ethyl methyl ketone, which interferes with the determination.

Selective reactions for the determination of epoxy groups in the presence of acrylic acids and aromatic amines were studied. Factors affecting results of the determination of epoxy groups were revealed. Procedures were developed for the determination of epoxy and carboxylic groups and epoxy and amine (aromatic) groups in the presence of each other. The reaction is conducted in excess HCl in the former case and in excess tetraethylammonium bromide in the latter case. Performance characteristics of the procedures were estimated.