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Elevated reaction order of 1,3,5-tri-tert-butylbenzene bromination as evidence of a clustered polybromide transition state : a combined kinetic and computational study. / Shernyukov, Andrey V.; Genaev, Alexander M.; Salnikov, George E. и др.
в: Organic and Biomolecular Chemistry, Том 17, № 15, 21.04.2019, стр. 3781-3789.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - Elevated reaction order of 1,3,5-tri-tert-butylbenzene bromination as evidence of a clustered polybromide transition state
T2 - a combined kinetic and computational study
AU - Shernyukov, Andrey V.
AU - Genaev, Alexander M.
AU - Salnikov, George E.
AU - Shubin, Vyacheslav G.
AU - Rzepa, Henry S.
PY - 2019/4/21
Y1 - 2019/4/21
N2 - The kinetics and mechanism of concurrent bromo-de-protonation and bromo-de-tert-butylation of 1,3,5-tri-tert-butylbenzene at different bromine concentrations were studied experimentally and theoretically. Both reactions have high order in bromine (experimental kinetic orders ∼5 and ∼7, respectively). According to quantum chemical DFT calculations, such high reaction orders are caused by participation of clustered polybromide anions Br 2n−1 - in transition states. Bromo-de-tert-butylation has a higher order due to its bigger reaction center demanding clusters of extended size. A significant primary deuterium kinetic isotope effect (KIE) for bromo-de-protonation is measured indicating proton removal is rate limiting, as confirmed by computed DFT models. The latter predict a larger value for the KIE than measured and possible explanations for this are discussed.
AB - The kinetics and mechanism of concurrent bromo-de-protonation and bromo-de-tert-butylation of 1,3,5-tri-tert-butylbenzene at different bromine concentrations were studied experimentally and theoretically. Both reactions have high order in bromine (experimental kinetic orders ∼5 and ∼7, respectively). According to quantum chemical DFT calculations, such high reaction orders are caused by participation of clustered polybromide anions Br 2n−1 - in transition states. Bromo-de-tert-butylation has a higher order due to its bigger reaction center demanding clusters of extended size. A significant primary deuterium kinetic isotope effect (KIE) for bromo-de-protonation is measured indicating proton removal is rate limiting, as confirmed by computed DFT models. The latter predict a larger value for the KIE than measured and possible explanations for this are discussed.
KW - ACID SYSTEMS
KW - SUBSTITUTIONS
KW - DENSITY
KW - CATIONS
UR - http://www.scopus.com/inward/record.url?scp=85064129451&partnerID=8YFLogxK
U2 - 10.1039/C9OB00607A
DO - 10.1039/C9OB00607A
M3 - Article
AN - SCOPUS:85064129451
VL - 17
SP - 3781
EP - 3789
JO - Organic and Biomolecular Chemistry
JF - Organic and Biomolecular Chemistry
SN - 1477-0520
IS - 15
ER -
ID: 19355395