Synthesis Of Degradable Polymer Monomer Based On CO₂

CO2is not only one kind of greenhouse gas, but also a C1resource which has most abundant storage capacity in the world. It possesses quite some advantages, such as nontoxic, noncombustible and inexpensive, etc. Therefore, it is a green and innovative method to synthesize chemicals by utilizing fixation of carbon dioxide.CO2is used to synthesize δ-lactone by reacting with1,3-butadiene, and (5-lactone can be polymerized to generate macromolecular compounds due to its special molecular structures, containing double-bond and ester functional group. This is a very interesting research work which extended the applications of δ-lactone in materials preparation.It is reported that direct ring-opening polymerization of δ-lactone is difficult to occur, therefore, the monomer is synthesized firstly via alcoholysis reaction which leads to ring cleavage of δ-lactone, after that, the biodegradable polyester can be prepared via repolymerization eventually.Firstly, the reaction conditions have been optimized through a model reaction between compound52and acetyl acetone. Through the optimization work in catalysts and solvents etc., it was found that the best catalytic activities have been obtained when using Pd(dba)2/PPh3as catalyst and CH2Cl2as solvent.Secondly, other active methylene compounds have been chosen to generate monomer. It was indicated that maximum yield93%has been achieved, when using a cyclic compound,1,3-dimethylpyr-imidine-2,4,6(1H,3H,5H)-trione57as nucleophile reagent. Subsequently, the corresponding bi-substituted compounds have been produced via diethyl malonate53reacting with ethyl acetoacetate54, but the yields were decreased a bit. Only single substitution was achieved if using nitro methane55, and no desired reaction occurred by using malononitrile56.