Diazotisation Mechanism of Heteroaromatic Amines. Diazotisation of 2-aminothiazole as an equilibrium
作者:Heinz Diener、Bilge Güleç、Peter Skrabal、Heinrich Zollinger
DOI:10.1002/hlca.19890720421
日期:1989.6.14
2-aminothiazole was measured in 65 to 75% (w/w) aqueous H2SO4. The kinetic solvent isotope effect of the diazotization in 72% D2SO4/D2O was determined (kH/kD = 5.8 ± 0.2). These data are consistent with a mechanism in which the 2-aminothiazole, protonated at the ring N-atom, but not at the NH2 group, is attacked by the NO+ ion. The reaction does not go to completion, but to an equilibrium. The equilibrium concentration
在65至75%(w / w)的H 2 SO 4水溶液中测定了2-氨基噻唑的重氮化率。确定了在72%D 2 SO 4 / D 2 O中重氮化的动力学溶剂同位素效应(k H / k D = 5.8±0.2)。这些数据与其中在环N-原子而不是在NH 2基上质子化的2-氨基噻唑被NO +离子攻击的机理一致。反应不会完全完成,而是达到平衡。重氮离子的平衡浓度在30,50,70和90%(w/ w)试剂的三种初始浓度(0.001、0.01和0.1m)下的H 2 SO 4。试剂和重氮离子的最终浓度与可逆过程一致。这是首次发现重氮化的定量证据。在所用酸度的很大范围内(H o = -1.73至-9.01),不可能计算独立于酸度的有意义的平衡常数。