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Thiophene series. XV The effect of leaving groups on the reactivity of nitro‐activated thiophene derivatives with sodium thiophenoxide
Author(s) -
Guanti Giuseppe,
Dell'Erba Carlo,
Macera Paola
Publication year - 1971
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.5570080402
Subject(s) - chemistry , reactivity (psychology) , thiophene , leaving group , nitro , medicinal chemistry , sodium , stereochemistry , group (periodic table) , organic chemistry , catalysis , medicine , alkyl , alternative medicine , pathology
The effect of leaving groups on the reactivity of 3‐X‐2‐nitrothiophene (1), 2‐X‐3‐nitrothiophene (II) and 2‐X‐5‐nitrothiophene (III) (X = Cl, Br, I, OC 6 H 4 NO 2 ( p ), SO 2 C 6 H 5 ) with sodium thiophenoxide has been examined. The results show that the reactivity ratio kIII/kII is always greater than unity and is relatively uninfluenced by changing leaving groups compared to the ratio kI/kII. The ratio kI/kII is greater or smaller than unity, according to following patterns of leaving groups\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm OC}_6 {\rm H}_4 {\rm NO}_2 (p) < {\rm Cl} < {\rm Br} < {\rm SO}_2 {\rm C}_6 {\rm H}_5 $$\end{document}Examination of the reactivity of the three series of compounds having Cl, Br, I and C 6 H 4 NO 2 ( p ) as leaving groups showed the absence of an “element effect” which indicates that in the transition states of these displacement reactions there is little breaking of the bond to the group being displaced.