The effect of using a methanol-water solvent mixture on pH oscillations in the palladium-catalyzed phenylacetylene oxidative carbonylation reaction
The effect of using a methanol-water solvent mixture on pH oscillations in the palladium-catalyzed phenylacetylene oxidative carbonylation reaction
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DOI：
10.1007/s11144-017-1282-z
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发表时间：
2018-02-01
影响因子：
1.8
通讯作者：
Novakovic, Katarina
中科院分区：
文献类型：
--
作者：
Parker, Julie;Novakovic, Katarina
钯催化的苯乙炔氧化羰基化反应在以甲醇为溶剂间歇进行时，在pH值、反应热和浊度上产生规律的振荡。以往对催化体系的研究表明，水在催化循环的行为中起着重要作用。进一步研究了这一作用，在甲醇-水混合物中进行了反应。实验表明，在所研究的条件下，当系统中的水浓度增加（0-30 V%）时，pH值的振荡是可行的。同时，振荡在视觉上发生了变化，随着水的比例增加，振荡从规则振荡转变为更逐步的行为。通过建立记录的pH值与HI浓度之间的关系，发现水浓度的增加抑制了HI的形成，从而减缓了反应中的自催化作用。当HI浓度在1 × 10(-3) mol L-1区域时，振荡开始。此外，随着系统中水量的增加，当振荡开始时，HI浓度略有下降。
The palladium-catalyzed phenylacetylene oxidative carbonylation reaction has been shown to produce regular oscillations in pH, reaction heat, and turbidity when conducted in batch with methanol as solvent. Previous studies of the catalytic system showed that water plays an important role in the behavior of the catalytic cycle. Investigating this role further, the reaction was performed in methanol-water mixtures. Experiments demonstrated that, under the conditions studied, oscillations in pH are feasible when the water concentration in the system is increased (0-30 V%). At the same time oscillations visually changed, being transformed from regular oscillations to more stepwise behavior as the proportion of water is increased. By establishing the relationship between the recorded pH and HI concentration it was found that increased water concentration suppresses HI formation and hence slows the autocatalysis in the reaction. It was also found that oscillations begin when the HI concentration is in the region of 1 x 10(-3) mol L-1. Additionally, as the amount of water in the system increases a slight decrease in the concentration of HI when oscillations start was noted.