Propylene polymerization sulfides

Chain transfer to monomer is much less prevalent for polymerizations with most of the anionic coordination initiators. Much higher molecular weights are thus possible in these polymerizations. For example, molecular weights of the order of 10 are reported for propylene polymerization by an initiator derived from diphenyltin sulfide and bis(3-dimethylaminopropyl)zinc. 

The cadmium chalcogenide semiconductors (qv) have found numerous appHcations ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds, eg, sulfide, tungstate, selenide, teUuride, and oxide, are used as phosphors in luminescent screens and scintiUation counters. Glass colored with cadmium sulfoselenides is used as a color filter in spectroscopy and has recently attracted attention as a third-order, nonlinear optical switching material (see Nonlinear optical materials). DiaLkylcadmium compounds are polymerization catalysts for production of poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVA), and poly(methyl methacrylate) (PMMA). Mixed with TiCl, they catalyze the polymerization of ethylene and propylene. 

Extensive studies of stereoselective polymerization of epoxides were carried out by Tsuruta et al.21 s. Copolymerization of a racemic mixture of propylene oxide with a diethylzinc-methanol catalyst yielded a crystalline polymer, which was resolved into optically active polymers216 217. Asymmetric selective polymerization of d-propylene oxide from a racemic mixture occurs with asymmetric catalysts such as diethyzinc- (+) bomeol218. This reaction is explained by the asymmetric adsorption of monomers onto the enantiomorphic catalyst site219. Furukawa220 compared the selectivities of asymmetric catalysts composed of diethylzinc amino acid combinations and attributed the selectivity to the bulkiness of the substituents in the amino acid. With propylene sulfide, excellent asymmetric selective polymerization was observed with a catalyst consisting of diethylzinc and a tertiary-butyl substituted a-glycol221,222. ... 

Anionic polymerization of alkylene sulfides was extensively studied by Sigwalt and collaborators. In contrast to propylene oxide, anionic polymerization of pro-... 

An optimal reaction-temperature of 65°C was claimed. The blackish brown TiSCl is very sensitive to oxygen and humidity. As no X-ray measurements have been made, additional work is needed. Titanium sulfide halides have also been claimed as catalysts for the polymerization of propylene (363). 

The range of monomers that can be incorporated into block copolymers by the living anionic route includes not only the carbon-carbon double-bond monomers susceptible to anionic polymerization but also certain cyclic monomers, such as ethylene oxide, propylene sulfide, lactams, lactones, and cyclic siloxanes (Chap. 7). Thus one can synthesize block copolymers involving each of the two types of monomers. Some of these combinations require an appropriate adjustment of the propagating center prior to the addition of the cyclic monomer. For example, carbanions from monomers such as styrene or methyl methacrylate are not sufficiently nucleophilic to polymerize lactones. The block copolymer with a lactone can be synthesized if one adds a small amount of ethylene oxide to the living polystyryl system to convert propagating centers to alkoxide ions prior to adding the lactone monomer. 

Kinetics of anionic ring-opening polymerization has hitherto been quantitatively studied and gave for two monomers, namely ethylene oxide [IS,12] and propylene sulfide [8.20]. Studies on these systems revealed that the living conditions can be achieved, facilitating quantitative determination of rateconstants of propagation on various kinds of ionic growing species. 

These ligands form extremely stable cation inclusion complexes, called cryptates, In which the cation Is completely surrounded by the ligand and hidden Inside the molecular cavity, and this leads to a considerable Increase of the interionic distance In the ion pairs. It has been shown that such ligands have a marked activating effect on anionic polymerizations (4,5,6). Moreover, the aggregates are destroyed and simple kinetic results have been obtained In the case of propylene sulfide (7,8,9). ethylene oxide (9,10,11) and cycloelloxanes (12) polymerizations. Though the... 

Propagation Constants of Free Ions and Ion Pairs for the Anionic Polymerization of Propylene Sulfide in THF at -30 C... 

Figure 2. Plot of log k vj. the reciprocal of interionic distance parameter of ion pairs for the anionic polymerization of propylene sulfide at —30°C in THF ( ) ...

In conclusion, it has been shown that use of cryptates for the anionic polymerization of heterocyclic monomers leatis to a tremendous increase of the rates of polymerization. There are two main causes to the higher reaction rates observed with cryptates. The first one is a suppression of the association between ion pairs in the non polar media, and the second one is the possibility of ion pairs dissociation into free ions in ethereal solvents like THP or THF. By this way, it has been possible to make detailed studies of the propagation reaction for propylene sulfide, ethylene oxide, and cycloslloxanes. 

With Na+, as a cation, the activation energies for the anionic polymerization of acrolein and propylene sulfide (11) are approximately the same. On the other hand, with Li+, it is impossible to compare the acrolein activation energy with the same monomer or another polar monomer because no result is found in the literature. Moreover, for the acrolein polymerization, (Raj u+) lower than ( > +). 

Propylene sulfide can be resolved more efficiently by using a mixture of diethylzinc and (S)-binaphthol (179). The polymerization affords, at 67% conversion, unreacted monomer, [a]D25 +51.8°, in 92% ee, together with optically active polymer, [a]D25 —103°. 

Ethylene sulfide,8 propylene sulfide,88 3-ohloropropylene sulfide,18 and cyclohexene sulfide1 have been converted into 2-chlarothioIs in 33, 60, 72, end 67% yields respectively by reaction with concentrated hydrochloric add. Dilute hydrochloric add, however, leads to more extensive polymerization. 3ft... 

Propylene sulfide (174) can also be polymerized enantiomer-selectively [252-262], In the polymerization with a ZnEt2-(-)-binaphthol initiator system at room temperature, the... 

Copper compounds are catalysts for the Michael addition reaction (249), olefin dimerizations (245, 248), the polymerization of propylene sulfide (142), and the preparation of straight-chain poly phenol ethers by oxidation of 2,6-dimethylphenol in the presence of ethyl- or phenyl-copper (209a). Pentafluorophenylcopper tetramer is an intriguing catalyst for the rearrangement of highly strained polycyclic molecules (116). The copper compound promotes the cleavage of different bonds in 1,2,2-tri-methylbicyclo[1.1.0]butane compared to ruthenium or rhodium complexes. Methylcopper also catalyzes the decomposition of tetramethyllead in alcohol solution (78, 81). 

The Step 2 product was dissolved in THF and treated with one equivalent of 0.5 M sodium methoxide in methanol at ambient temperature. The mixture was then treated with between 25 and 50 equivalents of propylene sulfide and polymerized for 30 minutes. It was further treated with approximately 10 equivalents of poly (ethylene glycol) monoacrylate as the end-capping agent. The reaction mixture was stirred overnight at ambient temperature and isolated by precipitation in methanol. 

Cationic polymerization of propylene sulfide provides a good example of a ocess in which, at the first, non-stationary stage, the originally formed active species (strained tertiary sulphonium fons holding a monomer molecule) are converted into the dormant species (non-strained sulfonium fons) which are at equilibrium with the strained ones ... 

In the cationic polymerization of heterocycles, a similar phenomenon was observed by Goethals in the polymerization of propylene sulfide and trans 2,3-dimethyl-thiirane. The latter monomer polymerizes rapidly and quantitatively to a linear polymer which is then relatively slowly converted into 3,4,6,7-tetramethyl-l, 2,5-tri-thiepane (J67a). In this particular process, the macroring formation is a practically irreversible reaction and differs in this sense from the equilibrium processes discussed so far. The irreversibility is due to the formation of one molecule of cis-butene per one molecule of a cyclic trithiepane ... 

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