The effects of. alpha.-substituents on the kinetic and thermodynamic stability of 4-methoxybenzyl carbocations: carbocation lifetimes that are independent of their …

TL Amyes, IW Stevens, JP Richard

Index: Amyes, Tina L.; Stevens, Ishmael W.; Richard, John P. Journal of Organic Chemistry, 1993 , vol. 58, # 22 p. 6057 - 6066

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Citation Number: 58

Abstract

The following new rate constants for reaction of a-substituted 4-methoxybenzyl carbocations, 4-MeOC6H&R1 (R2)+, with a solvent of 5050 (v/v) trifluoroethanol/water at 25" C and ionic strength 0.50 (NaC104) are reported 4-MeOCeH&H (OMe)+, k,= 2.2 X lo7 sl; 4-MeOCsHrCH (Ns)+, k,= 3.3 X lo6 sl; 4-MeOCeH4C (CH3) 2+, k,= 1.3 X lo7 sl; 4-MeOCeH&H (COzEt)+, k,= 1.4 X lo7 sl; 4-MeOCsH&CH3 (CF3)+, k,= 2.5 X lo7 sl. The values of k, for reaction of 4- ...