The rate constants for addition of the radical anion [O4S]•– at C=C and C=O double bonds of N,N-dimethylacrylamine have been evaluated by the electron paramagnetic resonance technique.

N -Acryloyl derivatives of histamine, monoethanolamine, and β-alanine, which contain imidazole, hydroxyl, and carboxyl functional groups, respectively, are synthesized and characterized. Copolymers, which are further divided into thermally precipitable and thermally nonprecipitable (soluble) fractions, are obtained via the free-radical copolymerization of N -vinylcaprolactam and the specified comonomers that is initiated by a persulfate–tertiary amine redox system in a medium of 10% aqueous dimethyl sulfoxide (DMSO) at 65°C. It is shown that the soluble fractions of the synthesized copolymers exhibit catalytic activity in the reaction of hydrolysis of 4-nitrophenyl propionate (NPP) at a temperature above the coil-to-globule transition.

We present a new concept for designing biomimetic analogs of enzymatic proteins; these analogs are based on the synthetic protein-like copolymers. α-Chymotrypsin is used as a prototype of the artificial catalyst. Our experimental study shows that in the course of free radical copolymerization of hydrophobic and hydrophilic monomers the target globular nanostructures of a “core-shell” morphology appear in a selective solvent. Using a mesoscale computer simulation, we show that the protein-like globules can have a large number of catalytic centers located at the hydrophobic core/hydrophilic shell interface.

The redox-initiated homopolymerization of N,N-dimethylacrylamide in a moderately-frozen aqueous medium yields cross-linked high-swelling cryogels instead of soluble polymers that are formed in water solutions at positive temperatures or both at positive and negative temperatures in formamide media. The comparison of swelling characteristics of the cryogels and especially synthesized cross-linked model hydrogels showed that the amount of crosslinks in the cryogels thus prepared was rather small, no more than 0.05-0.10 mol.% with respect to the total quantity of monomer units. The studies performed with NMR and EPR spectroscopies revealed that the crosslinks in such cryogels were formed owing to the generation of certain unexpected by-radicals via coupling of the initiating sulfate-anion-radical with the monomer at the carbonyl group of N,N-dimethylacrylamide. These radicals acted as bifunctional cross-linking agents. (C) 2014 Elsevier Ltd. All rights reserved.

The free-radical polymerization of N,N-dimethylacrylamide initiated by the redox pair ammonium persulfate-N,N,N′,N′-tetramethylethylenediamine in moderately frozen and liquid formamides is studied at temperatures 10–30°C below or above the temperature of crystallization (2.9°C) of the pure solvent at various monomer concentrations in the initial solution. When polymerization is conducted at temperatures below the temperature of crystallization of formamide, the frozen systems, as is evident from their phase diagrams, include the crystallized main bulk of the solvent and the noncrystallizing monomer concentrated in the unfrozen liquid microphase where the reaction occurs. It is found that, in the case of this cryopolymerization variant, the temperature dependences of the yield of the polymer and its viscosity-average molecular mass show an extremum pattern and the positions of maximum points relative to the temperature scale depend on the initial monomer concentration. It is shown that the molecular masses of cryopolymerization products are much higher and their molecular-mass distribution is wider than that of poly(N,N-dimethylacrylamide) samples synthesized through solution polymerization (above the temperature of crystallization of formamide) at the same concentration of the monomer.

Determination of metals in and experiments with inhibition and reactivation of 6-chlorohydroxyhydroquinone 1,2-dioxygenase from Streptomyces rochei 303 suggest that iron is the metal functioning in the active site of the enzyme. The substrate specificity of this enzyme was studied and its position among the enzymes mediating the beta-ketoadipate pathway of cleavage of hydroxylated aromatic compounds was determined. We suggest that there are both the simple and the modified ortho pathway of degradation of hydroxyhydroquinones and chlorohydroxyhydroquinones, in addition to the simple and ortho pathways of degradation of pyrocatechol and chloropyrocatechols.

We investigated the degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by cells of Streptomyces rochei 303 immobilized on various carriers. Polycaproamide fibre was chosen as the optimal carrier for immobilization. The cells immobilized on this carrier degraded high-concentrations of individual chlorophenols and their mixtures: from mono- to pentachlorophenol including the most persistent meta-substituted derivatives. During continuous fermentation in a column with continuous substrate and air flow at a maximal degraded concentration of 2,4,6-TCP of 1 g/l and the specific flow rate of 0.08 h−1, the efficiency of degradation was 720 mg 2,4,6-TCP/day (36 mg 2,4,6-TCP/day per gram of carrier). The above system of immobilized cells was operated continuously without any loss of activity for 2.5 months, the amount of degraded 2,4,6-TCP being 54 g. At a lower concentration of the reagent (150 mg/l) the system was operated without any decrease in its degradability and without any additional carbon source for 11 months.