Nitration of pyridine by dinitrogen pentoxide, a study of the reaction mechanism †
作者:Jan M. Bakke、Eli Ranes
DOI:10.1039/a703079g
日期:——
The nitration of pyridine and substituted pyridines by dinitrogen pentoxide (DNP) has been studied. The reaction of DNP with pyridine in either liquid SO2 or an organic solvent produces N-nitropyridinium nitrate (4). On reaction of this with aqueous solutions of SO2 or NaHSO3 three transient species are formed: N-nitro-1,4-dihydropyridine-4-sulfonic acid (5), N-nitro-1,2-dihydropyridine-2-sulfonic
研究了五氧化二氮(DNP)对吡啶和取代的吡啶的硝化作用。DNP与吡啶在液态SO 2或有机溶剂中的反应生成硝酸N-硝基吡啶鎓(4)。将其与SO 2或NaHSO 3的水溶液反应后,形成三个瞬时物质:N-硝基-1,4-二氢吡啶-4-磺酸(5),N-硝基-1,2-二氢吡啶-2-磺酸酸(6)和1,2,3,6-四氢-3-硝基吡啶-2,6-二磺酸(7)。化合物6和7可以是亚硫酸酯而不是磺酸。化合物5通过一级反应进行反应[ ΔH ‡ = 32(1)kcal mol –1,ΔS‡ = 31(4)cal K –1 mol –1 ],并形成3-硝基吡啶。化合物6快速转化为7,通过一级pH依赖反应 k obs = 1.9(4)×10 –4 s –1 + 3.5(2)×10 –2 [H + ] M –1 s –1进行反应}得到3-硝基吡啶。根据现有证据,反应是分子内反应或在溶剂笼中进行。根据报道的证据发现