IR spectra of substituted pyrroles

The IR spectra of 52 substituted pyrroles, including 24 1-vinylpyrroles, were thoroughly analyzed. The principal analytical bands of the pyrrole ring and the vinyl group were isolated. Doublet character of the bands of the stretching vibrations of the double bond ( ^v C=C) and the C-H (CH₂=) out-of-plane deformation vibrations, which indicates the presence of rotational isomerism relative to the N-vinyl bond, was detected. The integral intensify of the principal component of the ^v C=C doublet was measured for 12 of the 1-vinylpyrroles, and it is shown that it is practically independent of the structure of the alkyl substituents in the ring. Proof for the existence of a nonplanar gauche conformation for the 1-vinylpyrroles was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 910–914, July, 1977.     

Solvatochromism of Heteroaromatic Compounds: XVIII. Reversible Effect of the Medium on the UV spectra of 2-(2-Benzoyl-1-phenylethenyl)-5-phenylpyrrole

Theoretical (B3LYP/6-31G^*) and experimental (NMR, UV, and IR spectroscopy) data on the electronic and steric structure of 2-(2-benzoyl-1-phenylethenyl)-5-phenylpyrrole have been analyzed in the context of the hypothesis of the zwitter ionic nature of its ground state. The molecule involves a strong NH···O bond, and its ground state can be described as a hybrid of the neutral and zwitter ionic canonical forms; this conclusion was confirmed by the observation of a reversible medium effect on the electronic absorption spectrum of the substrate.     

Synthesis of 3- and 5-amino-5-(3)-(pyrrol-2-yl)isoxazoles

5-Amino-3-(pyrrol-2-yl)isoxazoles were selectively prepared by the reaction of 2-(2,2-dicyano-1-ethylthioethenyl)pyrroles with hydroxylamine in methanol. Under analogous conditions, 2-(2-carbamoyl-2-cyano-1-ethylthioethenyl) pyrroles with hydroxylamine gave 5-aminoisoxazoles and their structural isomers, 3-aminoisoxazoles (3-5% yield). The latter were selectively prepared by reacting 2-(2-carbamoyl-2-cyano-1-ethylthioethenyl)pyrroles with hydroxylamine in the presence of aqueous NaOH and from the products of intramolecular cyclization of 2-(2-carbamoyl-2-cyano-1-ethylthioethenyl)pyrroles, 1-ethylthio-3-iminopyrrolizines and hydroxylamine.     

Synthesis and modification of 1-vinylpyrrole-2-carbaldehyde polymers

1-Vinylpyrrole-2-carbaldehydes, viz., 5-phenyl-1-vinylpyrrole-2-carbaldehyde, 5-(2-thienyl)-1-vinylpyrrole-2-carbaldehyde, 1-vinyl-4,5,6,7-tetrahydroindole-2-carbaldehyde, and 1-vinyl-4,5-dihydrobenz[g]indole-2-carbaldehyde, are polymerized in the presence of 2,2-azobisisobutyronitrile to form soluble paramagnetic oligomers. A possibility of oligomer modification through the aldehyde moiety with amines and thiols was shown. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2134–2137, November, 2007.     

1,3,5-triphenylbenzene as unexpected by-product in the synthesis of 2,5-diphenylpyrrole from acetophenone oxime and phenylacetylene

Russian Journal of Organic Chemistry -     

Selective thermal oxidation of 2,3-dimethyl-5-(phenyldiazenyl)-1-vinyl-1H-pyrrole to the corresponding pyrrole-2-carbaldehyde: Stabilization of the pyrrole ring by phenylazo substituent

Russian Journal of Organic Chemistry -     

Copolymerization of N-Vinyl-4,5,6,7-tetrahydroindole with Acrylamide

Radical copolymerization of N-vinyl-4,5,6,7-tetrahydroindole with acrylamide in dimethylformamide was studied, and the relative activity constants of the monomers were determined.     

Electrocaloric effect in triglycine sulfate under equilibrium and nonequilibrium thermodynamic conditions

The direct and indirect measurements of intensive electrocaloric effect in a triglycine sulfate ferroelectric crystal are performed under equilibrium and nonequilibrium thermodynamic conditions implemented in the adiabatic calorimeter. The effect of the electric field parameters (frequency, profile, and strength) on the value of the effect and degree of its reversibility are studied. The difference between the temperature variation values in a switched-on and switched-off dc field under quasi-isothermal conditions is established. The low-frequency periodic electric field induces the temperature gradient along the electrocaloric element and heat flux from its free end to the thermostated base. A significant excess of the field switching-off rate over the switching-on rate leads to a noticeable intensification of the cooling effect.     

Phenol and anisol fluorescence quenching in aqueous micellar solutions

Phenol and anisol fluorescence quenching in aqueous micellar solutions is investigated on addition of H ₂ O ₂. It is established that the efficiency of interaction of the phenol molecule in water with hydrogen peroxide is higher than of anisol. In the phenol-H ₂ O ₂ system, the buildup of phenol fluorescence occurs in the presence of an anionic-reagent detergent. A decrease in the efficiency of phenol fluorescence quenching by hydrogen peroxide in aqueous solutions in the presence of CTAB and triton X-100 micelles is observed. The micellar media increase the efficiency of interaction of anisol with a quencher in comparison with phenol. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 73–79, April, 2006.