OH?-induced β-elimination reactions with 1-(2-Xethyl)-4-nitrobenzene substrates in solvent mixture H2O/CH3CN and H2O/DMSO: Reactivity and mechanism |
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| Authors: | Sergio Alunni Roberto Melis Laura Ottavi |
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| Institution: | (1) Dipartimento di Chimica, sez. Chimica Organica, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia, Italy |
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| Abstract: | The behaviour of 1-(2-bromoethyl) 4-nitrobenzene (1), N,N,N-triethyl-2-(4-nitrophenyl)ethanaminium bromide (2) and N,N-diethyl-N-2-(4-nitrophenyl)ethyl]octan-1-aminium bromide (3) in the OH−-induced elimination reactions with formation of 1-nitro-4-vinylbenzene in mixtures of DMSO/H2O or CH3CN/H2O has been investigated. With all three substrates an increase in dipolar aprotic solvent content implies a limited increase
of the second-order rate constant k
OH up to ≅605, and then an exponential increase is observed. The variation of activation parameters ΔH
# and dGS
#, measured in DMSO/H2O mixtures, is parallel for 1 and 2. This similar behaviour of 1 and 2 with respect to variation in solvent composition is evidence that it is not possible to use this technique of solvent effect
for the mechanistic diagnosis of elimination reactions. |
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| Keywords: | 1-(2-Bromoethyl) 4-nitrobenzene N N N-triethyl-2-(4-nitrophenyl)ethanaminium bromide N N-diethyl-N-[2-(4-nitrophenyl_ethyl]octan 1-aminium bromide OH− -induced elimination dipolar aprotic solvent |
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