Studies on the synthesis of carbon-carbon initiator diisobutyl 2,3-dicyano-2,3-diphenyl succinate and its crystal structural and initiating behavior

A novel carbon-carbon bond free radical initiator diisobutyl 2,3-dicyano-2, 3-diphenyl succinate (DBCPS) was synthesized and characterized by elemental analysis, IR, FAB-MS and H-1 NMR spectroscopy. The crystal structure of th e compound DBCPS was determined by single crystal X-ray diffraction techniq ues. The analytical results show that this crystal belongs to triclinic wit h space group P-1, and the cell parameters are a=1.060 3(2) nm, b=1.470 2(3 ) nm, c=0.794 4 nm, alpha =93.40(3)degrees, beta =99.12(3)degrees, gamma =1 03.90 (3)degrees, V=1.180 8(4) nm(3), D-c=1.216 Mg/m(3), Z=2, F(000)=452. T he molecular structure of DBCPS exhibits as a central symmetry, anti-confor mation and mesomer and the severe steric hindrance in the molecule also exe rts a distinct tension, abnormal bond angle and bond length. Its central C- C bond length is 0.159 2 nm, there is 0.048 nm elongated, and the elongatio n ratio 3.11% ( the normal bond length is 0.154 4 nm; and its corresponding ethyl derivative is 0.158 5 nm, the elongation ratio is 2.66%). There are two isomers, both Meso and DL, can be found for dimethyl and diethyl deriva tives respectively. However, because of the bigger steric hindrance, only o ne isomer, meso-form which has a lower potential energy was obtained for DB CPS. The polymerization of methyl methacrylate(MMA) initiated by DBCPS show ed the number-average molecular weight of the polymer (PMMA) increased whil e both conversion and polymerization time were increased, and the molecular weight distribution decreased with the increasing of reaction time corresp ondingly. Hence, it is inferred that DBCPS can serves as a thermal iniferte r and follows "living" free radical polymerization. The PMMA capped with th e fragments initiated the polymerization of styrene to yield block copolyme r PMMA-b-PSt.