Automorphism subgroups for designs with $$\lambda =1$$ λ = 1

Designs, Codes and Cryptography - Given an integer $$k\ge 3$$ and a group G of odd order,  if there exists a 2-(v, k, 1)-design and if v is sufficiently large then there...     

Chlorination and oxidation products formed from 1,2,4-trimethylbenzene in aqueous solution under the action of chlorine dioxide

Products of the reaction of 1,2,4-trimethylbenzene with chlorine dioxide in aqueous solution were studied. A scheme of 1,2,4-trimethylbenzene transformations was suggested. The influence exerted on the number of the reaction products by the ClO₂ dosage and time of its contact with the substrate was examined.     

2,4-diazapenta-1,4-dienes in the synthesis of 2,6-diaryl-3,5-dinitropiperidines

2,4,6-Triphenyl-and 2,6-diaryl-3,5-dinitropiperidines were synthesized in 70–79% yields by reaction of 1,3,5-triaryl-2,4-diazapenta-1,4-dienes with 2,2-dimethyl-and 2-phenyl-1,3-dinitropropanes.     

Reactions of 2-(2-Furyl)-1,3-dioxacycloalkanes with Triethylsilane

Russian Journal of Organic Chemistry -     

Homolytic telomerization of vinyltrimethylsilane with 5,5-dimethyl-1,3-dioxane

The homolytic telomerization of vinyltrimethylsilane by 5,5-dimethyl-1,3-dioxane follows three principal routes, with the formation of 2- and 4-substituted 5,5-dimethyl-1, 3-dioxanes and a formate ester. The rings in the reaction products (2-trimethylsilylethyl- and 4-trimethylsilylethyl-5,5-dimethyl-1,3-dioxane) exist in the chair conformation. The substituants in the 2- and 4-positions of the dioxane ring occupy equatorial positions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1035, August, 1986.     

Sensing the physicochemical nature of he and ne in micropores by adsorption measurements

He and Ne in contact with molecular sieves in the form of crystalline A zeolites and amorphous carbon molecular sieves fibers (CMSF) were studied by adsorption measurements. Classification of the effective enclosure of zeolitic apertures and of graphitic constrictions, as determined by recent temperature-programmed desorption mass spectrometry (TPD-MS) studies of adsorption of He and Ne onto these materials, was utilized in making a prudent choice of samples and experimental conditions. In view of the former TPD information, the behaviors of adsorption and volumetric measurements reported herein are straightforwardly interpreted. The combined TPD, adsorption isotherms, and dead volume data deepen the understanding of the physicochemical nature of adsorbed gas, where gas adsorption in the vicinity of pore constrictions and/or apertures as well as on the inner surface areas of pores and/or cages could be resolved. Previous conclusions that the huge activation energies measured for Ne/CMSF at high temperatures are unlikely to characterize chemical desorption but reflect those required for overcoming the barrier of effectively constricted apertures were confirmed by the volumetric data presented here. At 77 K, considerable He adsorption was observed in the porous solids and found to be responsible for abnormal deduced values of dead volumes. The occurrence of significant adsorption of He onto A zeolites and CMSF at 77 K warrants the realization that in cases concerning porous materials, volumetrically deduced quantities should not be taken for granted, but should be carefully considered and uniquely interpreted in relation to the specific experimental conditions under which they are taken.     

Synthesis and properties of heterocyclic analogs of 4-azidochalcone

A study has been made of the spectral and photochemical properties of a series of heterocyclic analogs of 4-azidochalcone, specifically the pyridine, quinoline, isoquinoline, and quinoxaline derivatives. It has been shown that the absorption spectra of most of the 4-azidocinnamoylarenes are shifted bathochromically in comparison with 4-azidochalcone. The quantum yields of photodissociation of the compounds that were investigated were found to vary within the limits 0.70±0.15. With steric hindrance for the planar conformation of the molecule, a hypsochromic shift of the absorption spectra is observed, along with a slight decrease of the quantum yield.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1340–1343, October, 1991.