Propylene/propene polymerization reaction

Many simple alkenes called vinyl monomers undergo polymer-forming (polymerization) reactions Ethylene yields polyethylene, propylene (propene) yields polypropylene, styrene yields polystyrene, and so forth. The polymer molecules that result may have anywhere from a few hundred to many thousand monomer units incorporated into a long chain. Some commercially important polymers are listed in Table 23.3. 

Polyolefins belong to a group of thermoplastics polymerized through polyaddition reactions of olefins (unsaturated hydrocarbons). The most important polyolefins are ethylene (ethene), CH2=CH2, which gives polyethylene, and propylene (propene), CH2=CHCH3, which gives polypropylene when polymerized. 

There has been some initial success in forming block copolymers using singlesite catalysts. These catalysts have to show no or only a slow chain transfer reaction, like living systems [132]. In a first step, only propylene is polymerized, forming a hard polypropylene block, then by addition of ethene a soft ethene/propene copolymer or a polyethylene block follows because ethene is inserted much faster. 

Although the reactivity increase caused by crown ethers and cryptands in anionic polymerizations has already found a wide range of application, more details have been reported and a number of questions concerning the type and the behavior of the different species present, both in the initiation and in the propagation steps, have been clarified by, for example, kinetic studies [235], Special polymerization reactions that were effected in the presence of crown compounds are those starting with butadiene, propene, styrene, 2-vinyl pyridine, ethylene oxide, propylene sulfide, isobutylene sulfide, methyl methacrylate, p-propyllactone, or e-caprolactone as monomers and alkali metals as initiators [238-246],... 

Small olefins, notably ethylene (ethene), propene, and butene, form the building blocks of the petrochemical industry. These molecules originate among others from the FCC process, but they are also manufactured by the steam cracking of naphtha. A wealth of reactions is based on olefins. As examples, we discuss here the epoxida-tion of ethylene and the partial oxidation of propylene, as well as the polymerization of ethylene and propylene. 

Propene undergoes little polymerization when treated with 96% sulfuric acid, the chief product being isopropyl hydrogen sulfate which yields isopropyl alcohol on hydrolysis. When 98% sulfuric acid is used, propylene is converted to conjunct polymer. Ethylene cannot be polymerized by sulfuric acid because the stable ethyl hydrogen sulfate and ethyl sulfate are formed attempts to obtain the polymerization by increasing the reaction temperature are unsuccessful because oxidation occurs. 

Similarly, the reaction of propene with 90% orthophosphoric acid at 125° at an initial pressure of 10 atmospheres yielded a homogeneous liquid product which presumably contained isopropyl phosphate (Ipatieff, 56). When this liquid was heated at 150° two layers were formed. The upper layer consisted of propylene polymer and the lower layer was phosphoric acid which was capable of polymerizing additional propene. 

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