A new algorithm for accurate evaluation of the generalized Bloch–Gruneisen function and its applications to MgB2 superconductor

The objective of this Letter is to provide an efficient and reliable analytical procedure for the generalized Bloch–Gruneisen function with the Debye temperatures for the wide temperature range using the binomial expansion theorems. As will be seen, the present formulation yields compact closed-form expressions which enable the ready calculation of Bloch–Gruneisen function for integer and noninteger values of parameter m. The proposed procedure guarantees the reliable application of the contribution of electron–photon interaction to the electrical resistivity of metals. Finally, the algorithm is used to simulate the variation of the resistivity and thermal conductivity against temperature sintered polycrystalline MgB₂. Furthermore, the comparison of the method with numerical calculations demonstrates the applicability and accuracy of the method.     

Asymmetric Synthesis of Chiral Norbornenes from Polybromocyclopentadienes

Effect of the conditions on the enantiomeric purity, overall yield, isomeric composition ofchiral polybromonorbornene Diels-Alder adducts of polybromocyclopentadienes and (-)-menthyl acrylatewas studied. Enantiomerically pure polybromonorbornenecarboxylic acids were obtained by resolution of the corresponding racemates through diastereoisomeric salts with l-ephedrine. The structure of the products was confirmed by the IR and ¹H NMR spectra.     

Six-membered cyclic semiaminal as intermediate in the synthesis of thiazoles from thiosemicarhazide and α-haloketones

Cyclization of thiosemicarbazide with methyl 3-chloro-2-oxo-3-phenylpropionate in MeCN results in 5-hydroxy-2-imino-5-methoxycarbonyl-6-phenylperhydro-1,3,4-thiadiazine. The structure of the product has been confirmed using spectral (IR,¹H,¹³C,¹³C{¹H} NMR) methods and chemical transformations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1962–1965, November, 1993.     

Infrared spectra of menthoxyalkylchloro-(alkoxy)silanes and chlorosilylpropionic and chlorosilylisobutyric acid menthyl esters

Conclusions The IR spectra of methyl- and phenylchloromenthoxysilanes, menthoxypropylalkylehlorosilanes, menthoxypropyl- and menthoxyethylmethylethoxysilanes, and also chlorosilylpropionic and chlorosilylisobutyric acid menthyl esters were studied. Assignments of the frequencies for a number of vibrations were made.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2151–2155, September, 1968.