Ethylene sulfide, oxidative polymerization

The polymerization tendencies of episulfideg are also encountered under acidic reaction conditions. Dilute hydrochloric acid, for example, instantly polymerizes ethylene sulfide to an amorphous powder. Under the same conditions ethylene oxide gives 2-chioroothanol in good yield. Hus may he attributed to tho greater tendency of sulfur as compared with oxygen to form onium ions. A comparison of the two reactions may he pictured as shown in Eqe. f3i>) and (40 . 

By nitric add and sulfuric add. The oxidation of ethylene sulfide with concentrated nitric acid leads to eulfoacetic add, HOaSCHjOOjH. and other condensed acids.8 Sulfuric acid, dilute or concentrated, appears to have only a polymerizing influence.18... 

Polymerization of ethylene oxide is a suitable example of the intramolecular tomina-tion. R)lyma ization of other thr -ntembwed monomers like ethylene sulfides and N-substituted aziridines also terminates intranwlecularly. This conclusion is based on the studio of the final monoma concentration and its dependence on the starting initiator concentration. 

These complexes lead to a considerable increase of the Interlonlc distance In the ion pairs and It has been shown that such ligands have a marked activating effect on anionic polymerizations (14,15, 16). Moreover, the aggregates are destroyed and simple kinetic results have been obtained in the case of propylene sulfide and ethylene oxide polymerizations (12). 

In a practical sense the hydrocarbon monomers that work best in anionic systems are styrene, a-methylstyrene, p-(tert-butyl)styrene, butadiene, isoprene, 2,3-dimethyIbutadiene, piperylene, stilbene, and 1,1-diphenylethylene. The latter two monomers give rise to alternating copolymers with other dienes but do not homopolymerize. Among the polar monomers (C) that can be polymerized are such monomers as 2-vinyIpyridine, pivalolactone, methacrylonitrile, methyl-methacrylate, ethylene oxide (not with Li-counterion), ethylene sulfide, and propylene sulfide. However, polymerization of many of these polar monomers suffers from side reactions and complicating termination or transfer reactions not present in the... 

Aliphatic ethylene sulfides often undergo the same ring-opening reactions as do the oxides, but polymerization usually prevents the isolation of much of the initial product of ring fission. However, good yields of 2-chlorothiols and 2-chlorothiolie acid esters are obtained by reaction with coned. HC1 and acyl chlorides.— E Cyclohexene sulfide — 2-chlorocyclohexyl thiolacetate. (F. e. and reactions s. W. Davies et al., Soc. 1949, 282 1950, 317.)... 

The polymerization of monomers with unbalanced enantiomeric composition was performed using achiral initiators in the case of propylene oxide [13, 29] and propylene sulfide [24, 29]. In both cases it was shown that the optical activity of nonpolymerized monomer was identical to that of the initial monomer introduced. This seems to eliminate, at least in these cases, a possible chain effect. Furthermore, in the copolymerization of propylene oxide [30] and propylene sulfide [31] with achiral monomers, such as ethylene oxide and ethylene sulfide using chiral initiators, the stereoelectivity ratio is not affected by the achiral comonomer. If an end-chain effect exists, a decrease of stereoelection should be observed with the incorporation of achiral ethylene oxide or ethylene sulfide units. 

Uses. Magnesium alkyls are used as polymerization catalysts for alpha-alkenes and dienes, such as the polymerization of ethylene (qv), and in combination with aluminum alkyls and the transition-metal haUdes (16—18). Magnesium alkyls have been used in conjunction with other compounds in the polymerization of alkene oxides, alkene sulfides, acrylonitrile (qv), and polar vinyl monomers (19—22). Magnesium alkyls can be used as a Hquid detergents (23). Also, magnesium alkyls have been used as fuel additives and for the suppression of soot in combustion of residual furnace oil (24). 

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. 

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. 

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. 

MC MDI MEKP MF MMA MPEG MPF NBR NDI NR OPET OPP OSA PA PAEK PAI PAN PB PBAN PBI PBN PBS PBT PC PCD PCT PCTFE PE PEC PEG PEI PEK PEN PES PET PF PFA PI PIBI PMDI PMMA PMP PO PP PPA PPC PPO PPS PPSU Methyl cellulose Methylene diphenylene diisocyanate Methyl ethyl ketone peroxide Melamine formaldehyde Methyl methacrylate Polyethylene glycol monomethyl ether Melamine-phenol-formaldehyde Nitrile butyl rubber Naphthalene diisocyanate Natural rubber Oriented polyethylene terephthalate Oriented polypropylene Olefin-modified styrene-acrylonitrile Polyamide Poly(aryl ether-ketone) Poly(amide-imide) Polyacrylonitrile Polybutylene Poly(butadiene-acrylonitrile) Polybenzimidazole Polybutylene naphthalate Poly(butadiene-styrene) Poly(butylene terephthalate) Polycarbonate Polycarbodiimide Poly(cyclohexylene-dimethylene terephthalate) Polychlorotrifluoroethylene Polyethylene Chlorinated polyethylene Poly(ethylene glycol) Poly(ether-imide) Poly(ether-ketone) Polyethylene naphthalate Polyether sulfone Polyethylene terephthalate Phenol-formaldehyde copolymer Perfluoroalkoxy resin Polyimide Poly(isobutylene), Butyl rubber Polymeric methylene diphenylene diisocyanate Poly(methyl methacrylate) Poly(methylpentene) Polyolefins Polypropylene Polyphthalamide Chlorinated polypropylene Poly(phenylene oxide) Poly(phenylene sulfide) Poly(phenylene sulfone)... 

We begin with the structure of a noble metal catalyst, where the emphasis is placed on the preparation of rhodium on aluminum oxide and the nature of the metal support interaction. Next, we focus on a promoted surface in a review of potassium on noble metals. This section illustrates how single crystal techniques have been applied to investigate to what extent promoters perturb the surface of a catalyst. The third study deals with the sulfidic cobalt-molybdenum catalysts used in hydrotreating reactions. Here, we are concerned with the composition and structure of the catalytically active surface, and how it evolves as a result of the preparation. In the final study we discuss the structure of chromium oxide catalysts in the polymerization of ethylene, along with the polymer product that builds up on the surface of the catalyst. 

In the anionic polymerization there are three monomers only that have been studied in more detail, namely ethylene oxide, propylene sulfide, and B-propiolactone. Some... 

Polymerizations of ethylene oxide and propylene sulfide were reviewed several times by the authors of the original results, namely the Paris and the Moscow groups (52), (40). One of us with Kazanski reviewed recently the recent Zita, including also polymerization of lactone s... 

References may be found in the literature to attempts made for the purpose of reacting ethylene in a variety of other ways to obtain useful products. Condensation and oxidation products are claimed to lie formed when ethylene mixed with steam, ammonia, or hydrogen sulfide is passed over catalysts at high temperatures.811 Unsuccessful attempts have been made to obtain acetone by reacting ethylene with hydrogen and carbon monoxide in a molal ratio of 1 2.5 1, respectively, at 300° C. and 150 to 250 atmospheres pressure in the presence of a basic zinc chromate catalyst. In this case methanol was formed, a portion of the ethylene polymerized, and a portion was reduced to ethane.888 No acetone was formed. 

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