摘要
本文首次报导了丝氨酸-BrO_3^--Mn^(2+)-Fe(phen)_3^(2+)-H_2SO_4体系的化学振荡反应,测定了振荡反应的浓度范围及最佳反应条件;分析了反应产物;研究了反应物浓度、反应温度、Cl^-、自由基抑制剂、CCl_4、丙酮等对振荡反应的影响;讨论了Br^-及Br_2在振荡反应中的作用,并对振荡反应机理作了研究。在此基础上,进一步研究了Br_2在振荡反应中的动力学行为,研究了三种BZ反应中常用作催化剂的金属离子(Ce^(3+)、Mn^(2+)及Fe(phen)_3^(2+))单独存在时的振荡现象。实验发现,当Mn^(2+)存在时,体系可发生三次振荡,而Ce^(3+)或Fe(phen)_3^(2+)存在时,均不能发生振荡。在Mn^(2+)存在时,加入Fe(phen)_3^(2+)可使振荡次数大为增加,此时Fe(phen)_3^(2+)为振荡反应的催化剂。文中对金属离子的催化机理作了系统的研究。
A new chemical oscillating reaction in the serine-BrO-3-lMn2+-Fe ( phen ) 32 + -H2SO4 system has been studied and its oscillating phenomena has been described in detail. The effects of many factors such as chloride, bromide and bromine on the oscillation have been studied. The results of reaction products analysis show that, the oxidized products of serine are CO2 and ( COOH )2, and the reduced products of bromate are Br- and Br2. The effects of temperature and concentration of the reactants on the oscillating parameters-the oscillating induction period ( tin ), the oscillating period (tp)and the oscillating life time ( t1 ) have been determined. A-ccordingly, the activation energy in the induction period and in the oscillating period has been calculated. The experimental results showed that the oscillation in the Ser-BZ system are controlled by both Br- and Br2, but Br2 plays the key role in this oscillation. Unlike the classical BZ oscillators in which Br2 was consumed by the bromination, Br2 was consumed by the reduction of serine in this system. The joint action of two metal ions, such as Mn2+ and Fe(phen)32+ , has been analyzed. It was found that the system can produce oscillation only when Mn2+ existed in the Ser-BZ system, and Fe(phen)32+ was also necessary for the sustained oscillation. In the Ser-BZ oscillating reaction, Fe(phen)32+ was the oscillating catalyst which took part in the autocatalytic reaction and Mn2+ catalyzed the oxidation of serine by bromate to produce some intermediates which could reduce bromine easily to reproduce bromide ion, and reduce Fe ( phen ) 33+ to reproduce the oscillating catalyst.
出处
《分子催化》
EI
CAS
CSCD
1991年第2期125-130,共6页
Journal of Molecular Catalysis(China)
