Linear free energy relationships in the thiophen series. Part I. Leaving group effect in piperidino-substitution in methanol of some 2-L-3-nitro-5-X-thiophens
- 1 January 1975
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 10,p. 989-993
- https://doi.org/10.1039/p29750000989
Abstract
The reaction rates at various temperatures for piperidino-substitution of some 2-L-3-nitro-5-X-thiophens (L = Cl, Br, I, OC6H4NO2-p, or SO2Ph; X = H, Br, CONH2, CO2Me, SO2Me, Ac, CN, or NO2) have been measured in methanol to give information on the influence of the leaving group and the substituent at C-5 on the position of the rate-determining transition state (r.d.t.s.) on the reaction co-ordinate. Taking into account the effects (electronic and steric) of the leaving group, the data obtained have been explained by a modified interpretation of the ρ values obtained. The ρ values give a measure of the sensitivity of the reaction to the changes in the position of the r.d.t.s. on the reaction coordinate as a function of the substituent at C-5. Dependence on the type of t.s. (early or late) is also shown.Keywords
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