| dc.description | THE STUDYOFTHEELECTRONICSTRUCTURE ANDREACTIVITYOF 5-(ADAMANTANE-1-YL)-4R-1,2,4-TRIAZOLE-3-THIOLES DERIVATIVESV. M. OdyntsovaZaporizhzhуa State Medical University,ZaporizhzhуaSummary:The electronic absorption spectra of 5-(adamantane-1-yl)-4-phenyl-1,2,4-triazole-3-thiole (I) and 5-(adamantane-1-yl)-4-methyl-1,2,4-triazole-3-thiole (II) in solvents of different polarity (water, 95 % ethanol, 0.1 M HCl, 0.1 M H2SO4, 0.1 M NaOH, n-hexane) are studied. It is established that the absorption band of compound I is characterized by the presence of only one maximum of the average intensity in the range from 250 to 262 nm, while compound II is in the range from 236 to 255 nm.Keywords: UV spectra, electronic structure, reactivity, derivatives of 5-(adamantane-1-yl)-4R-1,2,4-triazole-3-thioles.Introduction. The study of UV spectra of organic compounds that are derivatives of 1,2,4-triazole, untilrecently, little attention had been paid. In scientific publications to date there aren’t theoretical conclusions on the impact of the substitutes on the nature of the UV spectra of various derivatives of 1,2,4-triazole, and some publication sare devoted only to the study of the existence of the thion-thiole tautomerism derivatives of 1,2,4-triazole-3(5)-thione. We have investigated the change in the UV absorption spectra and the positions of maxima of the investigated substances, depending on the polarity of the used solvents. Additionally, we have studied the reactivity’s ability of the compounds І and II in order to predict the possible directions of the reaction.The aim of our study was to study the absorption’s spectra of 5-(adamantane-1-yl)-4R-1,2,4-triazole-3-thiolеs derivatives, namely: 5-(adamantane-1-yl)-4-phenyl-1,2,4-triazole-3-thiolе (І) and 5-(adamantane-1-yl)-4-methyl-1,2,4 - triazole-3-thiolе (ІІ) in the solvents of different polarity (water, 95 % ethanol, 0,1 M solutions of hydrochloric and sulphuric acids, 0,1 M solution of sodium hydroxide and n-hexane).Methods. To investigate the purity of the compounds І and II, we used a thin-layer chromatography method, and the identity of the intended composition of compounds – their actual composition was checked by elemental analysis using elemental GmbHanalyzer, from Germany. All used solvents and reagents were the qualification«chemically pure» and fully complied with the requirements of pharmacopoeial analysis. UV spectra were measured with a spectrophotometer «Specord 200».Results and discussion. Taking into account the chemical structure of the studied compound sand their absorption’s spectra is shown that the absorption band of the compound I is the result of applying π → πx transitions 1,2,4-triazole cycleon 1Lb– band of the phenyl radical. The absorption band of compound II is caused only by π→πx – transitions in parental chromophor, namely in 1,2,4-trizole. The use of the Extended Hückel method is based on the linear combination of atomic orbitals according to the program Chem office 11.0.1 Free Trial allowed us to predict the reactivity of the investigated compounds on the basis of quantum-chemical calculations of their atoms’ charges. The calculations indicate that 1,2,4-trіasole cycle of the compound I is π redundant due to the impact of the substitutes which are in the positions 3-SH – (-Ι, + M), 4-phenyl – (-Ι, + M), 5-adamantyl – (+ І). The acidic nature of SH-centre occurs due to the electron capture’s influence of the triazole ring. The sulphur atom shows a negative inductivee ffect (-I), but mesomeone effect is positive (+ M) + M > I. A deficiency of electron density (+ 0,0314774) is noted on the sulfur atom, and the charge (+0,0232612) is focused on the hydrogen atom of thiole group, resulting in the reaction of alkylation (SF) is gone according to the SH-acidic center.Conclusions. The absorption band of the compound І is the result of applying π→πх– transition triazole cycle on 1Lb– band of the phenyl radical and the absorption band of compound II is caused by π→πх– transitions only in the triazole cycle. The study of the results of quantum-chemical calculations of the compound I shows that 1,2,4-triazoline cycle is π redundant due to the impact of the substitutes inposition of 3-SH – (-I,+M), 4-phenyl – (-I,+M), 5-adamantyl – (+І).On the basis of quantum chemical calculations of compound II on Heukelem is found that the presence of a methyl radical inposition 4 has an impact on the distribution of electron density. In this case a methyl radical shows a positive inductivee ffect (+I). | uk-UA |
