Reactions of 1-aryl-2,5-dimethylpyrroles with ketones

1-Aryl-2,5-dimethylpyrroles react with acyclic ketones with acid catalysis to give geminal di-2-pyrrolyl derivatives independently of the ratio of the reagents. The reaction of cyclohexanone and cycloheptanone occurs analogously with 21 ratio of pyrrole to ketone. With an excess of cyclohexanone a cycloheptanone 1-aryl-2,5-dimethyl-3,4-dicyclohexenylpyrroles and substituted 4,5,6,7,8,9-hexahydro-2H-azulene[1,2-c]pyrrol-4-spirocycloheptane are produced respectively.Institute of Organic Chemistry, Ukraine National Academy of Sciences, Kiev 253660; e-mail: dov@fosfor.kiev.ua. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1506–1511, November, 1999.     

The Effect of Flow Ratio between Elements of Groups III and V on the Structure and Properties of InGaAs Layers Grown by Low-Temperature Molecular-Beam Epitaxy

InGaAs layers grown by low-temperature molecular-beam epitaxy on InP substrates at variable flow ratios between elements of groups III and V are investigated. Layers with a defect structure and low electrophysical parameters are shown to grow with an excess of the components of group III. Growth with high As flows gives rise to trapping of excess arsenic and generation of point defects (As_III antistructural defects and V_III vacancies). High-quality InGaAs layers at low growth temperatures are produced under near-stoichiometric conditions (V/III = 1–4).     

C‐phosphorylation of N‐arylpyrroles

Phosphorylation of N‐arylpyrroles with phosphorus tribromide proceeds regioselectively at the position 2 of the heterocyclic system. A 2‐to‐3 migration of the dibromophosphino group has been discovered, with its ease depending on the electronic nature of a substituent on the phenyl ring, solvent polarity, and the presence of pyridine hydrobromide in the reaction mixture. Further phosphorylation of 2‐ and 3‐monophosphorylated N‐arylpyrroles regioselectively involves the respective positions 4 and 5 of the heterocycle and is governed by the electron‐acceptor effect of the phosphorus‐containing substituent. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:223–228, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10012     

Defect formation in LT MBE InGaAs and GaAs

Results are obtained from the experimental studies (atomic force and transmission microscopy) of the influence of III/V flux ratio on the topography and internal structure of LT MBE films of InGaAs and GaAs. The layers are shown to contain both the surface growth defects — the volcano-like pits and microdrops of III group elements, and the bulk defects — dislocations, stacking faults, microtwins, and phase microheterogeneities. A high-temperature annealing results in the additional formation of thermal etching pits at the surface and the nanosized arsenic clusters in the bulk. The origin of the defects is discussed.     

Mass-spectral behavior and thermal stability of hetaryl analogs of unsymmetrical benzoins

The main path in the mass-spectral dissociation of the hetaryl analogs of unsymmetrical benzoins is β-fragmentation with cleavage of the central C-C bond. Here, the strongest peak in the mass spectra of α-benzoins is the peak of the hydroxymethylhetaryl cation, and in β-benzoins it is the peak of the hetaroyl cation. The thermal α → β isomerization of the hetaryl analogs of benzoin was studied. In the case of indole and pyrrole derivatives the formation of polyheterocyclic systems is observed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 515–521, April, 2006.     

Analysis of methods of determining the interlaminar shear strength of composite materials

Conclusions The range of geometrical dimensions of a sample in which the values of the interlaminar shear strength determined by four of the five methods discussed are practically constant has been established. Good agreement is shown in the values of the characteristic being determined which are obtained by each of the four methods. It has been established that the experimental data obtained by the method of three-point deflection of short beams does not characterize their interlaminar shear strength. It is shown that the interlaminar shear strength of glass-plastic and the shear strength of the adhesive with which it is prepared are very similar in value.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 640–648, July–August, 1976.     

Interaction of 3-Substituted Indoles with Phenylglyoxal

The interaction of 3-substituted indoles with phenylglyoxal has been studied. It was shown that a methyl group directs attack to the nitrogen atom, but hydrazonomethyl to position 2 of the indole. The reasons for the difference in regioselectivity are discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1653–1656, November, 2005.     

Influence of crystallization temperature on growth rate of epitaxial gallium arsenide layers in the system GaAs-AsCl3-H2

Conclusions Thus, consideration of the temperature dependences of the growth rate of singular and vicinal GaAs faces made it possible to determine the activation energy of the growth process in the kinetic region, to demonstrate the changes in the activation energy on passing from singular to vicinal faces, to estimate the magnitude of these changes, and also to analyze some distinctive features of the crystallization process which are related to the crystal chemistry of growing planes. The growth of GaAs epitaxial layers near the <111>B and <001> poles over a wide range of deposition temperatures is limited by the rate of the surface stage while for layers grown on substrates near the <111>A and <110> poles at high temperatures a significant role is played by outward-diffusion limitations which are associated primarily with the arsenic supply.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii., Fizika, No. 9, pp. 101–104, September, 1982.