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Nucleophilic Solvent Participation in the Solvolysis of Tertiary Bromoalkanes
Author(s) -
Liu KwangTing,
Hou SuJiun,
Tsao MengLin
Publication year - 2009
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200900063
Subject(s) - solvolysis , chemistry , nucleophile , reactivity (psychology) , solvent , medicinal chemistry , solvent effects , nucleophilic substitution , stereochemistry , organic chemistry , catalysis , hydrolysis , medicine , alternative medicine , pathology
The solvolysis of 2‐bromo‐2‐methylpropane ( 1B ), 2‐bromo‐2‐methylbutane ( 2B ), 2‐bromo‐2, 3‐di‐methylbutane ( 3B ), 2‐bromo‐2, 3, 3‐trimethylbutane ( 4B ), 3‐bromo‐3‐methylpentane ( 5B ), 3‐bromo‐2, 3‐dimethylpentane ( 6B ), 3‐bromo‐2, 2, 3‐trimethylpentane ( 7B ), 3‐bromo‐3‐ethylpentane ( 8B ), 3‐bromo‐3‐ethyl‐2‐methylpentane ( 9B ) and 2‐bromo‐2, 4, 4‐trimethylpentane ( 11B ) in 15 to 21 solvents was studied, and correlation analyses by using the single‐ and dual‐parameter Grunwald‐Winstein equations (Eqns 1 and 2) were examined. Substrates 7B, 9B and 11B showed excellent linear relationship ( R ≥ 0.997) in the log k ‐ Y Br plots and indicated limiting S N 1 mechanism for the solvolysis. On the other hand, bromides 1B‐6B and 8B gave linear correlations ( R = 0.987–0.996) with the dual‐parameter ( Y Br and N OTs ) equation (2) only, which indicated the presence of significant nucleophilic solvent participation. Normal trends of reactivity due to the relief of B‐strain could be found in the poorly nucleophilic trifluoroethanol. Similar to the corresponding chlorides, the overwhelming influence of nucleophilic solvent assistance results in the observed inverse order of reactivity: k ( 2B ) > k ( 3B ), k ( 5B ) > k ( 6B ) and k ( 8B ) > k ( 9B ).