Calculation of the electron structures and electronic spectra of 3-chloro- and 3-amino-1,2,4-triazole derivatives

3-Chloro- and 3-amino-1,2,4-triazole derivatives were subjected to a theoretical study by means of quantum-chemical calculation by the Pariser-Parr-Pople method. The experimentally observed electron transitions were assigned. The Cl atom and the NH₂ group in the 3 position of 1,2,4-triazole subject the electron system of the heteroring to substantial perturbation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 698–700, May, 1977.     

Electronic absorption spectra of 3-chloro- and 3-amino-1,2,4-triazole derivatives

The manifestation of acid-base interactions in the electronic absorption spectra of 32 1,2,4-triazole derivatives was studied. Ionization of the heteroring does not have a substantial effect on the energies of the electron transitions of 3-chloro-5-substituted 1,2,4-triazoles but causes changes in the extinctions of the absorption bands of 3-amino-5-substituted triazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 546–548, April, 1977.     

Chloro derivatives of 1,2,4-triazole

5-Substituted 3-chloro-1,2,4-triazoles were synthesized by diazotization of 5-substituted 3-amino-1,2,4-triazoles in hydrochloric acid. In addition to replacement of the amino group by a chloro group, diazotization of 5-aryl-3-aminotriazoles at high temperatures leads to chlorination of the aromatic ring.Translated from Khimiya Geterotsiklicheskikh Soedinenli, No. 3, pp. 421–423, March, 1976.     

Quantum-chemical analysis of the tautomerisim of 1,2,4-triazole and its amino and diamino derivatives

Calculation of the dipole moments and heats of formation for 1,2,4-triazole confirmed that it exists primarily in the unsymmetrical form, while similar calculations for 3-amino- and 3,5-diamino-1,2,4-triazoles showed that the amino tautomers with a hydrogen atom attached to the N-N bond are the preferred forms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 540–545, April, 1977.The authors thank S. P. Zacheslavskii for providing the program to determine optimization of geometry for the MINDO/2 method.     

1-(Triorganylsilyl)-2-(triethoxysilyl)ethanes

Conclusions The conditions were found for the hydrosilylation of CH₂=CHSi(OC₂H₅)₃ with triorganylsilanes in the presence of H₂PtCl₆ · 6H₂O in isopropanol, which assured a high yield (>90%) of the 1-(triorganylsilyl)-2-(tri-ethoxysilyl)ethanes. These conditions were used to synthesize 27 new 1-(triorganylsilyl)-2-(triethoxysilyl)-ethanes.The addition of (C₂H₅O)₃SiH to (CH₂=CHSi(CH₃)₃ in the presence of the same catalyst gave 1-(trimethyl-silyl)-2-(triethoxysilyl)ethane in 98.6% yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1622–1625, July, 1976.