Catalytic behavior of melamine glyoxal resin owards consecutive oxidation and oxy-Michael iddition

摘要

Synthesis of melamine glyoxal resin involves a catalyst-free, one pot eaction between melamine and glyoxal in DMF. The synthesized resins have a imilar morphological arrangement to that of layered materials as depicted by their KRD pattern and Raman spectra. The catalytic behavior of melamine glyoxal resin MGR) have been studied in allylic oxidation of cyclohexene and simultaneous Aichael addition. The MGR/solvent/02 oxidant system can be regarded as a metalree, additive-free, cost-effective and environmentally benign catalytic system. The xidative behavior of MGR is attributed to its ability to generate in situ organic eroxide species during the course of reaction. Generation of peroxide species is onfirmed by the KI/starch test and further confirmed by the complete suppression ffect of TEMPO (2,2,6,6-tetramethylpiperidine-l-oxyl) over oxidation. The ctivity for Michael addition can be attributed to the presence of a higher content of itrogen atoms, which serves as the active site. In oxidation, 28.1% conversion of yclohexene with 37.19 and 62.81% selectivities for cyclohexenol and cyclohexeone were observed, respectively. In consecutive oxidation and oxy-Michael ddition, 31.5% conversion of cyclohexene was observed with selectivities of 1.6% for cyclohexenone and 38.4% for alkoxy product