5-Hydroxy-2,3-dihydrobenzofuran-derived polyfunctional antioxidants 3. Synthesis and antioxidant activity of 2-dodecylthiomethyland 2-dodecylselenomethyl-5-hydroxy-4,6,7-trimethyl-2,3-dihydrobenzofurans

New sulfur- and selenium-containing analogs of α-tocopherol, namely, 2-dodecylthiomethyl- and 2-dodecylselenomethyl-5-hydroxy-4,6,7-trimethyl-2,3-dihydrobenzofurans were synthesized from 4-ethoxy-3,5-dimethylphenol through intermediate 2-allyl-4-ethoxy-3,5,6- trimethylphenol, 2-iodomethyl-, 2-dodecylthiomethyl-, and 2-dodecylselenomethyl-5-ethoxy- 4,6,7-trimethyl-2,3-dihydrobenzofurans. The compounds terminated oxidation chains of AIBN-initiated oxidation of styrene at 50 °C with rate constant of 5.0?10⁶ mol L^–1 s^–1 and stoichiometric coefficients of 1.9±0.1. The O—H bond dissociation energies for obtained compounds (326.5 kJ mol^–1) are calculated based on the measured rate constants.