New evidence supporting the mechanism of Gilch polymerization from an extremely twisted biphenyl monomer.
نویسندگان
چکیده
A p-biquinodimethane species formed during the Gilch polymerization of an extremely twisted biphenyl monomer has been identified by in situ(1)H-NMR spectroscopy for the first time. From the identification of chain ends, we conclude that the chain growth during Gilch polymerization of biphenyl type monomers is both radical and anionic in nature.
منابع مشابه
Synthesis and characterization of an oligomeric conjugated metal-containing poly(p-phenylenevinylene) analogue.
A new nickel-containing bis(bromobenzyl)salphen monomer suitable for Gilch polymerization was prepared. Reaction with KO(t)Bu in THF-DMF afforded primarily gels, but also soluble, conjugated oligomers that are red-shifted in the absorption spectrum when compared to the monomer. This spectral change, consistent with an enhanced conjugation length, was also compared with a suitable model compound...
متن کاملKINETICS AND MECHANISM OF GRAFT POLYMERIZATION OF ACRYLONITRILE ONTO STARCH INITIATED WITH POTASSIUM PERSULFATE
A new potassium persulfate redox system has been investigated for the graft polymerization of vinyl monomers. In this study potassium persulfate system was used for initiation the polymerization. Graft polymerization of acrylonitrile (AN) onto starch (Sta) was carried out in aqueous solution using potassium persulfate (I) redox system. It was found that the percentage of grafting and rate of gr...
متن کاملRecent advances in the polymerization of butadiene over the last decade
The stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining TiCl4 or TiCl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. Subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...
متن کاملModelling the catalyst fragmentation pattern in relation to molecular properties and particle overheating in olefin polymerization
A two-dimensional single particle finite element model was used to examine the effects of particle fragmental pattern on the average molecular weights, polymerization rate and particle overheating in heterogeneous Ziegler-Natta olefin polymerization. A two-site catalyst kinetic mechanism was employed together with a dynamic two-dimensional molecular species in diffusion-reaction equation. The i...
متن کاملPolymerization of propylene in a minireactor: Effect of polymerization conditions on particle morphology
Gas phase polymerization of propylene was carried out in a semi-batch minireactor using a commercially supported Ziegler–Natta (ZN) catalyst. The influence of variables including monomer partial pressure, external electron donor, reaction temperature and time on the particle morphology and size distribution was investigated. Generally, more uniform fragmentation and particle densities were obta...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Chemical communications
دوره 48 62 شماره
صفحات -
تاریخ انتشار 2012