The Preparation And Application Of Porous Organic Polymer Based On Functionalization Of N-heterocyclic Carbene

Since the first isolation of “free” N-heterocyclic carbene(NHC) by Arduengo in1990, N-heterocyclic carbene(NHC) has attracted considerable attention owing to its excellent characters. It could coordinate with varies of metals to form stable NHC-transition metal complexes, which were extensively applied to homogeneous catalysis. For example, the famous Grubss-II catalyst was highly efficient in olefin metathesis reactions. N-heterocyclic carbene(NHC) could also be applied to various catalytic reaction as catalyst alone, such as N-heterocyclic carbene named IPr was used to catalyze the formylation of amines. Compared with system of NHC-metal complexes, this system is greener and cleaner. However, low selectivity of reaction and unrecyclability of catalyst in NHC monomer catalytic system, limit its efficient application in catalysis. In order to solve the above problems, through functional modification of N-heterocyclic carbene, porous organic polymer based on functionalized N-heterocyclic carbene was synthestised in this paper and was applied to the formylation of amines, to realize the high selectivity of reaction and recycling of catalyst. During the experiment, it is discovered that the reaction can proceeded smoothly under the catalyst-free condition and aprotic polar solvent as reaction medium. Base on the interesting phenomenon, we also studied alone and developed the catalyst-free system.1. Porous organic polymer based on functionalization of N-heterocyclic carbene:preparation and catalytic application in the formylation of amines.Start from simple materials, porous organic polymer was conveniently synthesized through functional modification of N-heterocyclic carbene and trimerization reaction of terminal alkyne groups. The material exhibited high catalytic activity and selectivity in the formylation of amines and carbon dioxide. After the end of the reaction, products and catalyst were separated by centrifugation, recycled catalyst could be used for at least four times with a slight loss of activity.2. Mechanism study of the formylation of amines and carbon dioxide in catalyst-free systemAs is reported, the nucleophilicity and basicity of amines could be tuned by solvation and polarization in different solvents, based on this, a simple reaction system used formylation of amines and carbon dioxide was developed, aprotic polar solvent plays a vital role in the system. Throughout in situ NMR, probable reaction path was speculated and proved, finally a plausible mechanism involving silyl carbamates intermediate is proposed.