摘要
苯基异氰酸酯(ArNCO)是一种重要的工业原料,它的商品生产方法是通过硝基苯还原成苯胺,苯胺再与光气发生羰基化反应. 这种方法存在两个缺点,(1)生产中要利用光气;(2)有副产物HCl生成.
The oxidative alkoxycarbonylation of aniline catalyzed by three inorganic polymer- palladium complexes [silica- supported polytitazane-palladium (Ti-N-Pd) , polyalumazane-palladium (Al-N-Pd), polysilazane-palladium (Si-N-Pd)] have been investigated (Reaction 2). It has been found that the oxidative alkoxycarbonylation of aniline could be carried out under relatively mild conditions by using a small amount of palladium complex of inorganic polymer instead of palladium chloride described in reference (1), and the turnover numbers could amount to 300 at 160℃ after 6 hours, 2100 after 23 hours.
Inorganic polymers, silica-supported polytitazane(Ti-N), polyalumazane(Al-N)and polysilazane(Si-N)were prepared. They were reacted with PdCl2 ?2H2O respectively to give palladium complexes of these inorganic polymers, Ti-N-Pd, Al-N-Pd and Si-N-Pd. The results indicated that the catalytic activety of Ti-N-Pd is similar to that of Al-N-Pd, and that of Si-N-Pd is relatively low at 140℃. The catalytic activity is affected by reaction temperature, the ratio of CO to O2 and the amount of CuCl2. For example, in the presence of Al-N-Pd, the turnover numbers increase from 40 to 300 as temperature rises from 120℃ to 160℃ under 2.5 MPa CO and 1 MPa O2 after 6 hours. But the turnover numbers decrease with increasing the pressure of CO from 2.5 to 5 MPa under O2 1 MPa, i.e.with increasing the ratio of CO to O2.The amount of CuCl2 influences not only the yield of methyl phenylcarbamate (ArNHCOOCH3), but also the composition of products. The best amount of CuCl2 is found under the condition Cu2+ / Pd2+ = 2. In addition, hydrochlor ide plays an important role in this system. The catalytic mechanism of this reaction is believed to be similar to that for the Wacker reaction.
出处
《分子催化》
EI
CAS
CSCD
1989年第1期76-79,共4页
Journal of Molecular Catalysis(China)
