Raman Scattering Study of Natural and Synthetic Compounds Containing Polyene Chains

Doklady Physics - The dependence of Raman spectra of the molecules containing polyene chains on the conjugation length, structure of side and end groups, and isomer type is analyzed theoretically.     

Sorption of Copper(II) Ions by Apple Pectin Modified with Organic Pharmacophores

Russian Journal of Physical Chemistry A - The sorption properties of apple pectin, native and modified by pharmacophores (nicotinic, salycilic, 5-aminosalycilic, and anthroic acids), are...     

A New Approach to Producing Metaphosphates and Phosphorylating in Mild Conditions

Abstract

The fomation of monomeric metaphosphate has been postulated before, mainly i pyrolytic [1,2] or photolytic [3] fragmentation reactions. Meantime, these reactive intermediats are presumed to participate in the processes of electrophilic phosphorylation in living organisms [4]. In this connection it is reasonable that an active interest is being shown in the development of methods of generating metaphosphates in mild conditions [4–7] compatible with biological systems in order to simulate biological phosphoryl-transfer reactions.     

Raman Structural Study of Copolymers of Propylene with Ethylene and High Olefins

Nascent form of random copolymers of propylene with ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene was studied by Raman spectroscopy. The most significant spectral alterations with a change in propylene content were observed in two lines at 809 and 841 cm⁻¹. The first line corresponds to vibrations of polypropylene helical chains in the crystalline phase, while the second one is associated with vibrations of polypropylene helical chains having isomeric defects. Raman data confirm that conformational composition and phase state of copolymer macromolecules strongly depend on the comonomer content as well as on the size of the comonomer units.     

Copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with ethylene glycol vinyl ether in aqueous medium

The radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride (AMAC) (M₁) with ethylene glycol vinyl ether (M₂) in an aqueous medium proceeds at a high rate to afford random copolymers. The reactivity ratios equal to r ₁ = 2.18 and r ₂ = 0.01 indicate that AMAC is a more active comonomer. The overall reaction order in comonomers is 2.4, and the effective activation energy is 97.4 ± 2 kJ/mol. The monomer M₁ enters into copolymerization by both of the double bonds with the formation of pyrrolidinium structures in the chain through the cyclization stage.     

Effect of solvent nature on free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride and maleic acid

The free-radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid in DMSO proceeds to yield statistical copolymers. When the reaction is carried out in methanol, the copolymers of constant compositions (N,N-diallyl-N,N-dimethylammonium chloride: maleic acid = 2: 1) are formed over a wide range of comonomer ratios in the starting mixture. The formation of alternating copolymers in this case may be attributed to formation of donor-acceptor complexes between the comonomers in the methanol solution, as evidenced by UV spectrophotometry. The kinetic features of the process have been investigated, and the relative activities of the monomers have been assessed. ¹³C NMR studies have demonstrated that, regardless of the solvent nature, both double bonds of N,N-diallyl-N,N-dimethylammonium chloride are involved in copolymerization via intermolecular cyclization accompanied by formation of pyrrolidinium structures.     

Radical copolymerization of <Emphasis Type="Italic">N,N</Emphasis>-diallyl-<Emphasis Type="Italic">N,N</Emphasis>-dimethylammonium chloride and maleic acid in various solvents

Radical copolymerization of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid in various solvents was studied. The solvent effect on the relative activity of the monomers and the possibility of preparing copolymers of preset composition were examined.     

Quantitative characterization of the orientation of macromolecules in intercalated nanocomposites of polyolefins/layered silicates by Raman spectroscopy

Raman spectroscopy is used to study variations in the orientational order of macromolecules in the uniaxially drawn intercalated nanocomposites based on two polymer matrices (polyethylene (PE) and isotactic polypropylene (PP)) and a filler (modified clay (MC)). The orientation parameters of macromolecules measured using Raman spectroscopy are compared with the X-ray data. It is demonstrated that, for the uniaxially drawn PE-MC and PP-MC intercalated nanocomposites, the filler impedes the orientation along the draw direction for the macromolecules localized in the noncrystalline phase of the polymer matrix. The orientational ability of the PE and PP crystallites in nanocomposites is not affected by the filler.     

Electrochemical behavior of nickel bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 dibromide in an aprotic solvent

The electrochemical behavior of bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 and its nickel dibromide complex on dropping mercury and glassy carbon electrodes in an aprotic solvent was studied by AC polarography and cyclic voltammetry. Both the ligand and the nickel ion complex were shown to undergo electroreduction. The electrochemical reduction of nickel bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 dibromide occurred stepwise and formed intermediate nickel(I) species.     

Acylethynylpyrroles as a platform for the one-pot access to 2-(pyrrol-2-yl)-3-acylpyridines via the dihydrogenative annelation with propargylamine

Acylethynylpyrroles, available via the transition metal-free coupling of pyrroles with acylhaloacetylenes are readily annelated with propargylamine in a one-pot step-wise procedure: catalyst-free heating (60–65?°C, 6–16?h) in DMSO and then keeping for 2.5?h with CuI at the same temperature. The products are pyrrolyl-pyridines isolated in good to excellent yields (56–94%). It is experimentally shown that dehydrogenation of intermediate dihydropyridine moiety is not resulted from the oxidation with DMSO (Me₂S was not detected) or air (argon blanket) and is likely associated with the CuI catalysis.