碳-碳键引发剂2,3-二氰基-2,3-二苯基丁二酸二异丁酯的合成、结构及引发性能研究

Studies on the Synthesis of Carbon-carbon Initiator Diisobutyl 2,3-Dicyano-2,3-diphenyl Succinate and Its Crystal Structural and Initiating Behavior

合成了具有较大空间位阻的碳 -碳键型引发剂 2 ,3-二氰基 -2 ,3-二苯基丁二酸二异丁酯 ,测定了其分子结构 ,其中心碳 -碳键长达 0 .1 5 92 nm.对其引发甲基丙烯酸甲酯进行自由基聚合的研究结果表明 ,聚合物分子量随反应时间的延长而逐步增大 ,而聚合物分子量分布则逐渐变小 .聚合反应按照自由基“活性”

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 \{\}\+1H NMR spectroscopy. The crystal structure of the compound DBCPS was determined by single crystal X ray diffraction techniques. The analytical results show that this crystal belongs to triclinic with 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, α =93 40(3)° , β =\{99 12(3)°\}, γ =103 90(3)°, V =1 180 8(4) nm 3, D c=1 216 Mg/m 3, Z =2, F (000)=452 The molecular structure of DBCPS exhibits as a central symmetry, anti conformation and mesomer and the severe steric hindrance in the molecule also exerts 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 elongation 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 derivatives respectively. However, because of the bigger steric hindrance, only one isomer, \%meso\% form which has a lower potential energy was obtained for DBCPS. The polymerization of methyl methacrylate(MMA) initiated by DBCPS showed the number average molecular weight of the polymer(PMMA) increased while both conversion and polymerization time were increased, and the molecular weight distribution decreased with the increasing of reaction time correspondingly. Hence, it is inferred that DBCPS can serves as a thermal iniferter and follows 'living' free radical polymerization. The PMMA capped with the fragments initiated the polymerization of styrene to yield block copolymer PMMA b PSt.