Centro de Investigación y Desarrollo Tecnológico en Electroquímica, Parque Tecnológico Querétaro Sanfandila , 76703 Sanfandila, Pedro Escobedo, Querétaro, Mexico.
Departamento de Química del Centro de Investigación y Estudios Avanzados del I.P.N., Av. Instituto Politécnico Nacional 2508 , Apdo. Postal 14-740, C. P. 07360, Mexico City, Mexico.
J Org Chem. 2016 Aug 5;81(15):6329-35. doi: 10.1021/acs.joc.6b00962. Epub 2016 Jul 21.
Competition between hydrogen bonding and proton transfer reactions was studied for systems composed of electrogenerated dianionic species from dinitrobenzene isomers and substituted dihomooxacalix[4]arene bidentate urea derivatives. To analyze this competition, a second-order ErCrCi mechanism was considered where the binding process is succeeded by proton transfer and the voltammetric responses depend on two dimensionless parameters: the first related to hydrogen bonding reactions, and the second one to proton transfer processes. Experimental results indicated that, upon an increase in the concentration of phenyl-substituted dihomooxacalix[4]arene bidentate urea, voltammetric responses evolve from diffusion-controlled waves (where the binding process is at chemical equilibrium) into irreversible kinetic responses associated with proton transfer. In particular, the 1,3-dinitrobenzene isomer showed a higher proton transfer rate constant (∼25 M(-1) s(-1)) compared to that of the 1,2-dinitrobenzene (∼5 M(-1) s(-1)), whereas the 1,4-dinitrobenzene did not show any proton transfer effect in the experimental conditions employed.
研究了由电化学产生的二硝基苯异构体和取代的二氢同氧杂杯[4]芳烃双齿脲衍生物的二阴离子物种组成的体系中氢键和质子转移反应之间的竞争。为了分析这种竞争，考虑了二阶 ErCrCi 机制，其中结合过程随后是质子转移，伏安响应取决于两个无维参数：第一个与氢键反应有关，第二个与质子转移过程有关。实验结果表明，随着苯基取代的二氢同氧杂杯[4]芳烃双齿脲浓度的增加，伏安响应从扩散控制波（其中结合过程处于化学平衡）演变为与质子转移相关的不可逆动力学响应。特别是，1,3-二硝基苯异构体显示出比 1,2-二硝基苯（约 5 M(-1) s(-1))更高的质子转移速率常数（约 25 M(-1) s(-1))，而在实验条件下，1,4-二硝基苯没有显示出任何质子转移效应。
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