Premium
Effects of ring substituents on the reactivity of thionphenoxide ions towards some nitro‐activated thiophene derivatives
Author(s) -
Guanti Giuseppe,
Dell'Erba Carlo,
Macera Paola
Publication year - 1973
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570100623
Subject(s) - chemistry , nucleophile , medicinal chemistry , thiophene , bromine , substrate (aquarium) , reactivity (psychology) , ring (chemistry) , nucleophilic substitution , ion , nitro , chlorine , inorganic chemistry , organic chemistry , catalysis , alkyl , medicine , oceanography , alternative medicine , pathology , geology
The rates of nucleophilic substitution of bromine on 3‐bromo‐2‐nitrothiophene (1) and 2‐bromo‐3‐nitrothiophene (II) by o‐, m ‐, and p ‐substituted thiophenoxide ions bave been measured in methanol at 20.02°. The rate of thiophenoxy‐debromination is always higher when the reaction center is in the β‐position (substrate I) rather than in α‐position (substrate II). Plots of the log k against σ°‐constants for the reaction of the substituted thiophenoxides towards I and II have ρ‐values of ‐0.78 (for substrate I) and ‐0.76 (for substrate II). Deviations from linearity for p ‐substituents with strong +M and ‐M effect are discussed. A comparison of proton basicity, carbon basicity, and nucleophilicity of the thiophenoxide ions has also been made.