钌催化降冰片烯开环移位聚合的研究

1. 华东理工大学金属有机化学研究室
• 发布日期:2000-08-15

Ruthenium-Catalyzed ring-opening metathesis polymerization of norbornene initiated by O~2

Qian Yanlong;Chen Bin;Jin Junting;Huang Jiling

• Published:2000-08-15

CpRuCl(PPh~3)~2/O~2和CH~3OCH~2CH~2CpRuCl(PPh~3)~2/O~2体系对降冰片(NBE)开环移位聚合(ROMP)有活性，降冰片烯的转化率和聚降冰片烯主链双键顺反比与气氛催化剂摩尔比及催化剂本身性质有关。在实验的基础上提出了钌催化降冰片烯开环移位聚合的可能机理。

Katayama and coworkers used TpRuCl(＝C＝CHPh)(PPh~3)[Tp=hydridotris (pyrazolyl)borate] as a catalyst precursor for ring-opening metathesis polymerization (ROMP) of norbornene (NBE). As Cp'RuCl·(PPh~3)[Cp'= (un)substituted cyclopentadienyl] compounds also can reacted with HC≡ CPh to form vinylideneruthenium complexes which might be active for the ROMP of NEB, we examined the activity of CpRuCl(PPh~3)~2 and HC≡ CPh system for the polymerization of NBE. But the activity of this system was poor. Lately, O~2 was used as cocatalyst instead of HC≡ CPh and found to form in situ an efficient catalyst system for the ROMP of NBE. The catalytic activity of another Ru complex [ (CH~3OCH~2CH~2Cp)RuCl(PPh~3)~2] was also examined in this article. The influence of different monomer/catalyst, O~2/catalyst and polymerization temperature is stuided. The polymerization conversion is a function of O~2/catalyst ratio, when the ratio is between 1 to 3, the polymerization conversion is high, when the ratio is higher or lower, the polymerization conversion is decreased. The ratio of monomer/catalyst has a little effect on the conversion, and the conversion can slightly be improved by elongating the polymerization time to 72 hour. the higher polymerization temperature is beneficial to the polymerization conversion. This implies that the catalytic centers are stable at higher temperature. The trans-content of the PNBE is dependent on O~2/catalyst molar ratio, polymerization temperature and the nature of the catalyst. Three typical polymer samples were characterized by ^1H NMR (CDCl~3). There were two signals at δ=9～10 in the ^1H NMR spectrum, these peaks may be the absorption of protons on aldehyde group formed in the polymerization process. According to our experiment and the work of Ivin and coworkers, we suggest a possible mechanism of polymerization of NBE catalyzed by Cp'RuCl(PPh~3)~2. First the ruthenium complex and oxygen react to form a ruthenium oxygen complex, then the complex reacts with NBE to钌催化降冰片烯开环移位聚合的研究