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Reactivity of some tertiary chlorides with olefinic and methoxy neighboring groups. A case of extended π, n‐participation
Author(s) -
Jurić Sandra,
Kronja Olga
Publication year - 2002
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.492
Subject(s) - chemistry , solvolysis , kinetic isotope effect , deuterium , enthalpy , aqueous solution , reactivity (psychology) , medicinal chemistry , ethanol , stereochemistry , reaction rate constant , kinetics , organic chemistry , hydrolysis , thermodynamics , medicine , physics , alternative medicine , quantum mechanics , pathology
Tertiary 2‐chloro‐2‐methyl‐5‐methoxypentane ( 2 ) solvolyzes with a significantly reduced secondary β‐deuterium kinetic isotope effect (substrate with two trideuteromethyl groups), and with smaller entropy and enthalpy of activation than the reference saturated analog 4 [ k H / k D = 1.35 ± 0.01 VS k H / k D = 1.79 ± 0.01; ΔΔ H ≠ = −11 kJ mol −1 ; ΔΔ S ≠ = −30 J mol −1 K −1 , in 80% (v/v) aqueous ethanol], indicating participation of the methoxy group in the rate‐determining step. 2‐Chloro‐2,5‐dimethyl‐8‐methoxy‐5( E )‐octene ( 3 ) solvolyzes with a further reduction of the isotope effect, and drastically smaller activation parameters [ k H / k D = 1.16 ± 0.01; ΔΔ H ≠ = −33 kJ mol −1 ; ΔΔ S ≠ = −106 J mol −1 K −1 , in 80% (v/v) aqueous ethanol], suggesting that the solvolysis of 3 proceeds with extended π, n‐participation, i.e. the assistance of both neighboring groups occurs in the rate‐determining step. Copyright © 2002 John Wiley & Sons, Ltd.