TY JOUR TI THEORETICAL STUDY OF THE MECHANISM OF THIACROWNEFIR FORMATION KW reaction mechanisms KW nucleophilic substitution KW thiacrown ether KW acetylene-allene allylic rearrangement KW electron density functional theory KW B3LYP JO Modern Technologies and Scientific and Technological Progress AU Chirkina, E.A. PY 2026 IS 2026 PB Federal State Funded Educational Establishment of Higher Education «Angarsk State Technical University»