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本文研究了在50％NaOH,CH_2Cl_2体系中相转移催化产生的二氯及二溴卡宾与对位取代的苯乙烯反应的相对速率常数k_(rel),并用Brown式(lgk_(rel)=lgk_0+σ~+P~+)进行了线性相关分析.在此条件下,二氯及二溴卡宾都具有亲电性,其中二氯卡宾的选择性大于二溴卡宾.本文还测定了上述相转移反应中,反应物烯烃、溴仿浓度随时间变化的情况,并用动力学公式对所得的曲线进行了分析,得出在此条件下,反应为二级,其中对烯烃和溴仿各为一级.溴仿过量时,反应对烯烃呈准一级.
In this paper, the relative rate constant k_ (rel) of the reaction of dichloro and dibromocarbene with para-substituted styrene produced by phase-transfer catalysis in 50% NaOH and CH_2Cl_2 system was studied and expressed as Brown’s equation of lgk_ (rel) = lgk_0 + σ ~ + P ~ +). Under these conditions, both dichloro and dibromocarbene have electrophilicity, and the selectivity of diclocarbene is greater than that of dibromocarbene.In this paper, the phase transfer reaction , The concentration of reactant and bromoform changed with time, and the kinetic equation was used to analyze the obtained curve. Under this condition, the reaction was of the second order, of which the order of the olefin and the bromoform was one order. For bromoform excess, the reaction is quasi-one level for the olefin.