Activated aromatic substitution by piperidine or [1-2H]piperidine in benzene. Dependence of kinetic deuterium isotope effect on the group displaced
作者:Francesco Pietra、Dario Vitali、Sergio Frediani
DOI:10.1039/j29680001595
日期:——
concentration in benzene. Both the extent of rate acceleration by piperidine and the value of the kinetic deuterium isotope effect vary with the leaving group. When the leaving group is chloride, contrary to a previous report, the reactions are found to be only very mildly accelerated, and in a linear fashion, by piperidine. Moreover, substitution of deuteriated amine (90% deuteriated) for piperidine does not
1-氯-4,7-二硝基萘(A),4-氯-3-硝基三氟甲苯(B,B'),2,4-二硝基苯基环己基醚(C),1-氟-4-硝基苯( D)或1-氟-4,7-二硝基萘(E)与哌啶或[ 1-2 H]哌啶仅形成N -4,7-二硝基萘-(A,E),N -2-nitro-4 -三氟甲基苯基-(B,B'),N -2,4-二硝基苯基-(C)或N已经测量了-4-硝基苯基-哌啶(D)作为苯中亲核试剂浓度的函数。哌啶加速速率的程度和动力学氘同位素效应的值都随离去基团而变化。当离去基团是氯时,与先前的报道相反,发现哌啶仅以线性方式非常缓慢地促进了反应。此外,用氘代胺(90%氘代)代替哌啶不会明显改变动力学。当为环己氧基-(C)或氟化物(D,E)时,获得三级动力学(胺浓度为二级)。轻胺在氘代化合物上的相对反应性对于反应C为1·49±0·03,对于反应E为1·03±0·04,并且ca。对于反应D,为1·1。这些事实在中间体