Development of novel membranes with optimal performance, selectivity, and stability is a key research area in membrane technology. In the present work aromatic polyamidoimideurea (PAIU) is synthesized and tested as promising membrane material for separation of water and alcohol mixtures. The PAIU membrane structure, density, and transport properties are studied. Mass transfer of water and isopropanol through the membrane is estimated by sorption and pervaporation tests to determine equilibrium sorption degree, diffusion coefficients, flux through the membrane, and separation factor. Two techniques of sorption study from liquid and from vapor phases are used as novel approach to experimental study of mass transfer. The vapor sorption calorimetry permits to analyze the behavior of the polymer material in sorption process. In pervaporation of water–isopropanol mixture, almost pure water mainly permeates through PAIU membrane. To improve the performance, a double layer membrane containing a thin PAIU layer on the surface of porous poly(phenylene oxide) support is developed. The double layer membrane is extremely effective in dehydration of isopropanol.

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The structure of the condensation products of 2-hydroxy-and 2-sulfanylbenzohydrazides with a series of aldoses (L-arabinose, D-ribose, L-ramnose, D-galactose, D-glucose, D-mannose) was studied by 1 H and 13 C NMR spectroscopy. The condensation products of monosaccharides with 2-hydroxybenzohydrazide in DMSO-d 6 solution exist as equilibrium mixtures of linear hydrazone and cyclic pyranose and furanose forms, the cyclic tautomers being represented by two stereoisomers (α-and β-anomers). The aldose condensation products with 2-sulfanylbenzohydrazide in the crystalline state have cyclic 1,3,4-benzothiadiazepine structure, while in DMSO-d 6 solution they undergo complete or partial isomerization into cyclic pyranose tautomer.Condensation products of 2-sulfanylbenzohydrazide with monocarbonyl compounds tend to undergo intramolecular cyclization via nucleophilic addition of the SH group at the C=N bond with formation of seven-membered benzo-1,3,4-thiadiazepine ring [1-3]. In some cases this process is reversible, so that equilibrium mixture of linear 2-sulfanylbenzoylhydrazone and cyclic benzothiadiazepine tautomers may exist in solution.In continuation of our previous studies [1-3], in the present work we examined the structure of the condensation products obtained from 2-hydroxy-and 2-sulfanylbenzohydrazides IIa and IIb and a series of aldoses Ia-If. Compounds IIIa-IIIl were synthesized in good yields (55-90%) by heating equimolar amounts of the corresponding monosaccharide (L-arabinose, D-ribose, L-ramnose, D-galactose, D-glucose, D-mannose) and hydrazide in boiling methanol for a short time (see Experimental).2-Hydroxy-and 2-sylfanylbenzoylhydrazones IIIaIIIl are complex tautomeric systems that are capable of existing as cyclic five-and six-membered tautomers A and C and linear hydrazone structure B. In addition, condensation products IIIg-IIIl derived from aldoses and 2-sulfanylbenzohydrazide (IIb) could give rise to seven-membered 1,3,4-benzothiadiazepine form D as a result of attack by the SH group on the C=N bond. It should be also taken into account that each cyclic form A, C, and D may be a mixture of two stereoisomers [α-and β-anomers for structures A and C and (2R)-and (2S)-stereoisomers for structure D]. The formation of analogous seven-membered cyclic 1,3,4-benzoxadiazepine tautomers for 2-hydroxybenzoylhydrazones IIIa-IIIf via attack by the OH group on the C=N bond should be ruled out. It is known that condensation products of 2-hydroxybenzohydrazide with aldehydes and ketones have exclusively linear structure and they do not tend to undergo the above cyclization [4,5].In all experiments, the 1 H and 13 C NMR spectra were recorded at definite time intervals starting from the moment of dissolution until the end of transformations. In addition, the structure of the compounds under study in the crystalline state was confirmed by solid-phase high-resolution 13 C NMR spectroscopy

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