一种对钯催化剂有害杂质的光谱鉴定

Optical Spectral Verification of A Harmful Impurity to Palladium Catalyst

乙二醛和苄胺在甲酸的催化作用下,可以合成六苄基六氮杂异伍兹烷(HBIW),但是产物中含有的少量杂质会对HBIW氢解脱苄时使用的钯催化剂产生危害,致使氢解产率降低或失败。采用多次重结晶的方法提取了HBIW中的杂质,用常压制备色谱分离得到一种主要杂质晶体;应用FTIR,1H-NMR,ESI-MS,元素分析等方法分析鉴定了该杂质是N,N’-草酰二苄胺;按文献中的方法合成了N,N’-草酰二苄胺,用FTIR,1H-NMR,EI-MS进行了表征,其光谱分析图谱与分离杂质一致;在钯催化的HBIW氢解脱苄反应体系中,当加入其量的0.9%合成的N,N’-草酰二苄胺时钯催化剂将完全失效。

The condensation of glyoxal with benzylamine leaded to hexabenzyl-hexaazaisowurtzitane（HBIW） with formic acid catalyst, and at the same time some side products were produced. Some impurities in HBIW would be harmful to the palladium catalyst used in the hydrogenolysis of HBIW, subsequently resulting in the low yield or failure of the catalytic reaction. The impurities in hexabenzylhexaazaisowurtzitane were distilled by means of recrystal technic, which were isolated by preparative chromatograph. The structure of the main impurity was studied with FTIR, ^1H-NMR, ESI-MS, and element analysis. The result shows that the structure is comfirmed as N,N＇-dibenzyl-oxalamide. which was synthesized in the way reported in the literature, and was charactered by FTIR, 1H-NMR and EI-MS. And the optical spectra data of the sample synthesized and the substance isolated from the impuries were the same, testifying that the substance isolated was N, N＇-dibenzyl-oxalamide ulteriorly. N, N＇- dibenzyl-oxalamide was added in the hydrogenolysis system of HBIW catalyzed by Pd catalyst. The result shows that N, N＇- dibenzyl-oxalamide can reduce the activity of Pd catalyst, and when the quantity of N,N＇-dibenzyl oxalmine added achievs 0. 9% of the weight of HBIW, the reaction of catalytic hydrogenolysis fails.