Oxidation of heavy 1- olefins (C12= - C20=) with TBHP using a modified Wacker system
Oxidation of heavy 1- olefins (C12= - C20=) with TBHP using a modified Wacker system
复制标题
DOI：
10.1016/j.jcat.2009.12.001
复制
发表时间：
2010-03
影响因子：
7.3
通讯作者：
J. M. Escola;J. Botas;C. Vargas;M. Bravo
中科院分区：
文献类型：
--
作者：
J. M. Escola;J. Botas;C. Vargas;M. Bravo
采用改进的Wacker体系，以TBHP为氧化剂，乙腈为溶剂，在80°C下进行重质烯烃（C12-C20）的氧化。该系统允许1-十八烯氧化，2小时后转化率达到90%，对2-十八酮的选择性为60%，而添加β-环糊精并没有增加2-十八酮的产量。正十二烷+1-十二烯的等摩尔混合物的氧化显著增强了对2-十二烷酮的选择性，在不存在正链烷烃的情况下，2小时后产生63%而不是34%，这可能是由于正十二烷的稀释效应，其降低了异构化反应的程度。等摩尔混合物C12=+C16=+C20=在等摩尔量的它们相应的正构烷烃的存在下的氧化导致几乎完全的转化率和对2-甲基酮的选择性在70-90%内，由于它们在两相体系中的较高溶解度，随着链长的减小而增强。催化剂的活性下降后，两个反应周期表明其失活的钯簇的形成。然而，通过将（1-十二碳烯）/（PdCl 2）比增加到100，可以在活性和选择性方面获得类似的结果，这预期通过降低钯聚集的程度来增加催化剂寿命。在这方面，所报道的系统是相当有前途的重1-烯烃氧化为甲基酮。
The oxidation of heavy olefins (C12–C20) was carried out using a modified Wacker system with TBHP as oxidant and acetonitrile as solvent at 80°C. This system allowed the oxidation of 1-octadecene giving rise to 90% conversion with 60% selectivity towards 2-octadecanone after 2h while the addition of β-cyclodextrins did not increase the production of 2-octadecanone. The oxidation of a equimolar mixture of n-dodecane+1-dodecene enhanced markedly the selectivity towards 2-dodecanone yielding 63% instead of 34% in the absence of n-paraffin after 2h, likely due to a dilution effect of the n-dodecane which reduces the extent of the isomerization reactions. The oxidation of a equimolar mixture C12=+C16=+C20=in the presence of equimolar amounts of their corresponding n-paraffins gave rise to practically complete conversion and selectivities toward 2-methylketones within 70–90% enhancing with decreasing chain length due to their higher solubility in the biphasic system. The activity of the catalyst dropped after two reaction cycles indicating its deactivation by the formation of palladium clusters. However, it was possible to obtain similar results in terms of activity and selectivity by increasing the (1-dodecene)/(PdCl2) ratio to 100, which is expected to increase the catalyst lifetime by decreasing the extent of palladium aggregation. In this regard, the reported system is rather promising for the oxidation of heavy 1-olefins towards methyl ketones.