物理化学学报 >> 1987, Vol. 3 >> Issue (04): 351-356.doi: 10.3866/PKU.WHXB19870404

研究论文 上一篇    下一篇

高效液相色谱法对烷基黄原酸合钴(Ⅲ)与二甲胺反应动力学的研究

王安周; 霍宁钦*   

  1. 河北大学化学系
  • 收稿日期:1985-12-25 修回日期:1986-07-05 发布日期:1987-08-15
  • 通讯作者: 霍宁钦

STUDY ON THE KINETICS OF THE REACTIONS BETWEEN TRIS (ALKYLXANTHATO) COBALT (Ⅲ) AND DIMETHYLAMINE BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Wang Anzhou; Huo Shouqin*   

  1. Department of chemistry; Hebei University; Baoding
  • Received:1985-12-25 Revised:1986-07-05 Published:1987-08-15
  • Contact: Huo Shouqin

摘要: 本文用高效液相色谱法研究了黄原酸合钴(Ⅲ)[Co(RXan)_3(R=Et, Me, Bz)]与二甲胺HNMe_2在正己烷中的反应动力学。首次用液相色谱分离了钴(Ⅲ)与取代黄原酸RXan及二甲基二硫代氨基甲酸Me_2DTC生成的混合配体络合物。发现Co(RXan)_3与HNMe_2反应生成Co(Me_2DTC)_3的取代反应是分三步进行的。另外发现反应有Me_2NCSOR生成。对第一步取代反应的动力学研究发现, 反应对Co(RXan)_3是一级, 对HNMe_2是三级。反应是由两个平行反应组成的。最后讨论了反应机理, 进一步证明了反应是亲核取代反应。

Abstract: The reactions between cobalt xanthates, CoA_3(A=RXan), and dimethylamine are investigated by means of high-performance liquid chromatography(HPLC). The reaction mixtures, containing CoA_3, CoA_2B, CoAB_2, and CoB_3(B=dimethyl dithiocarbamate), are separated on a Zorbax-sil column by mixed eluent of n-hexane and isopropanol (90:10). The retention times of the complexes are found to be increasing with the increase of the number of dimethyldithiocarbamate ligand in the complexes, i.e. CoB_>CoB_2A>CoBA_2>CoA_3(Fig.1, Fig.2). Further HPLC study shows that the reaction involve three steps of substitutions. The -OR groups are replaced one after another by-NMe_2 group (Fig.3). A new reacton product, dimethylthiourethane, is also discovered. Kinetic study on the first step of substitution in n-hexane reveals that the reactions are first order to cobalt complexes and 3rd order to dimethylamine (Fig.4, Table 1). The rate constants at 298 K for the complexes increase in the series, Co(EtXan)_3, Co(MeXan)_3, Co(BzXan)_3. The reaction mechanism is discussed and the present results favour the nucleophilic substitution prediction.