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A simple preparative synthesis of 8-hydrazino-3-methyl-7-b-methoxyethylxanthine was developed. Reaction of the obtained hydrazinoxanthine with aldehydes and ketones produced several previously undescribed 8-ylidenehydrazino derivatives of 3-methyl-7-b-methoxyethylxanthine. PMR spectroscopy confirmed the structures of the synthesized compounds. Biological tests established that several of the synthesized compounds had pronounced antimicrobial, antifungal, and antioxidant activity and could be recommended for further research.

The extraction characteristics of amino acids and mono-amides of acids were studied using copolymers of N-vinylformamide with 1-vinyl- and 1-methacryloyl-3,5-dimethylpyrazole as extractants. Synthesis of water-soluble copolymers was carried out by radical copolymerization in dioxane with thermoinitiation with dinitro-azobisisomoic acid. The distribution coefficients and the degree of extraction of analytes for a single extraction in the presence of a salting out agent are calculated. To determine the representatives of amino acids, the method of capillary electrophoresis was used. The most effective extraction systems for the extraction of amino acids and monoamides of acids are proposed: the intrinsic viscosity of polymers, the concentration of polymer and analyte solution, the ratio of phase volumes, the ratio of the mole fractions of N-vinylformamide to 1-vinyl and 1-methacryloyl-3,5-dimethylpyrazole. The results of the most effective interfacial distribution of lysine between a water-salt solution and an extractant are presented, which is a copolymer of N-vinylformamide with 1-methacryloyl-3,5-dimethylpyrazole. The concentration of the copolymer and the ratio of the volumes of equilibrium phases at which the maximum degree of lysine extraction is reached are established. A copolymer of N-vinylformamide with 1-vinyl-3,5-dimethylpyrazole is used for simultaneous extraction of cystine, asparagine and glutamine. The established extraction characteristics allowed a successful separate determination of the amino acid cystine and monoamides (asparagine and glutamine) in a joint presence in an aqueous solution. When choosing the conditions for separate electrophoretic determination of amino acids, the optimal composition of the buffer solution, the type and concentration of the micelle was found. The dependence of the structure of the analytes on their interphase distribution was established, and the complexing power of the copolymers of N-vinylformamide with 1-vinyl- and 1-methacryloyl-3,5-dimethylpyrazole was revealed with respect to the representatives of amino acids. The extraction systems used on the basis of N-vinylformamide copolymers are distinguished by ecological and economic expediency, good metrological indices.

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