高等学校化学学报 ›› 1982, Vol. 3 ›› Issue (2): 243-250.

• 论文 • 上一篇    下一篇

重稀土与偶氮氯膦Ⅲβ型反应动力学研究及机理的探讨

林智信, 曾云鹗   

  1. 武汉大学化学系
  • 收稿日期:1980-11-07 出版日期:1982-04-24 发布日期:1982-04-24

STUDIES ON THE KINETICS AND MECHANISMOF β-TYPE REACTION OF HEAVIER RAREEARTHS WITH CHLOROPHOSPHONAZO (Ⅲ)

Lin Zhixin, Zeng Yune   

  1. Department of Chemistry, Wuhan University, wuhan
  • Received:1980-11-07 Online:1982-04-24 Published:1982-04-24

摘要: 一定条件下,偶氮氯膦Ⅲ的重稀土螯合物可由α型转化成β型。连续扫描的谱图表明:α型是瞬时形成的。随着反应进行,α峰下降而β峰上升。在恒溫、Yb:R=1:1和pH=3.2时,测得非缓冲体系和缓冲体系(NaAc—HCl)的反应级数分别为2和1,表观活化能分别为71.1KJ/mol和49.8KJ/mol。对于许多缓冲体系,具有亲核基团的缓冲介质能够加速此转化过程。在此缓冲体系中,β型螯合物的生成速率随氢离子浓度的增大而减小,随缓冲介质浓度增大而增大。实验还表明:两个α型分子形成一个β型分子并释放出一个质子。据此,对缓冲体系和非缓冲体系分别拟出了合理的机理,稳态处理后的动力学速率方程满意地解释了所有实验事实。最后讨论了反应机理的可能模式。

Abstract: Under a certain experimental condition, a-type of heavier rare earths chelates of chlorophosphonazo (III) can be converted to β-type. In continuous scanning spectrogram, it is shown that α-type is formed instantaneously. The α-peaks decline and the β-peak raises when the reaction is in process. when Yb:R = l:1 and pH = 3.2, we had determinated at constant temperature that the order of reaction is equal to 2 and 1 for nonbuffer system and buffer system (NaAc-HCl) while apparent activation energy is equal to 71.7 KJ/mol and 49.8KJ/mol, respectively. For many buffer systems of interest, it is clear that buffer medium of having nucleophilic groups can accelerate the converted process. In these buffer systems the observed formation rate of β-type chelates decreases with increasing of hydrogen ion concentration and increases with the buffer medium concentration. The experimental result tells us that two a-type molecules combine into a β-type molecule and liberate a proton at the same time.