Methyloxirane Propylene Oxide

A similar system was studied by Furukawa and Saegusa10). These authors found that modification of the initiating system with an amine considerably increases the yield of the high molecular weight polymer and concluded therefore that a coordinative anionic mechanism operates in the system. 

Propylene oxide-based elastomers became commercially available in 1972 under the trademark Parel 12). Parel elastomers are sulfur curable copolymers of PO and alkyl glycidyl ether prepared with an aluminumalkyl-water-acetylacetone catalyst. Thus, the polymerization mechanism should be classified as coordinative anionic. 

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Recently (79MI50500) Sharpless and coworkers have shown that r-butyl hydroperoxide (TBHP) epoxidations, catalyzed by molybdenum or vanadium compounds, offer advantages over peroxy acids with regard to safety, cost and, sometimes, selectivity, e.g. Scheme 73, although this is not always the case (Scheme 74). The oxidation of propene by 1-phenylethyl hydroperoxide is an important industrial route to methyloxirane (propylene oxide) (79MI5501). 

The manufacture and uses of oxiranes are reviewed in (B-80MI50500, B-80MI50501). The industrially most important oxiranes are oxirane itself (ethylene oxide), which is made by catalyzed air-oxidation of ethylene (cf. Section 5.05.4.2.2(f)), and methyloxirane (propylene oxide), which is made by /3-elimination of hydrogen chloride from propene-derived 1-chloro-2-propanol (cf. Section 5.05.4.2.1) and by epoxidation of propene with 1-phenylethyl hydroperoxide cf. Section 5.05.4.2.2(f)) (79MI50501). 

Methyloxirane (propylene oxide) is a colourless, water-miscible liquid, bp 35°C. It is produced commercially from propene and tert-hMtyX hydroperoxide in the presence of molybdenum acetylacetonate [8]. 

One method for the preparation of epoxides from alkenes involves (1) treating the alkene with chlorine or bromine in water to form a chlorohydrin (or bromohydrin) followed by (2) treating the halohydrin with a base to bring about intramolecular displacement of Cl . These steps convert propene first to l-chloro-2-propanol and then to methyloxirane (propylene oxide). 

Although the process is general, for the specific addition process shown in Scheme 8.62, that is, the addition of methanol (methyl alcohol, CH3OH) to 2-methyloxacyclopropane (2-methyloxirane, propylene oxide) (Table 8.6, item 22), it is seen that the acid-catalyzed reaction occurs by a mixture of what appears to be (substrate dependent) SnI and Sn2 processes with the protonated oxygen of the oxirane serving as the leaving group. As shown, both 2-methoxy-l-propanol and l-methoxy-2-propanol are obtained. 

Mono- and disaccharides are highly hydrophilic substances. They are produced in large volumes, are available in highly pure form, and are relatively cheap [4,5]. They may be, and indeed have been, used as hydrophilic substrates for the synthesis of nonionic surfactants. In 1999, the worldwide production of the latter was about 3.6 3.8 million metric tons, i.e., approximately 38% of total surfactant production [6]. The majority of the conventional nonionic surfactants are oligooxyethylene (and oxypropylene) chain-containing compounds obtained in the reaction of oxirane (ethylene oxide) or methyloxirane (propylene oxide) with hydrophobic intermediates that contain a functional group with an active hydrogen atom [7]. Only recently, the direct reaction of oxirane with fatty acid methyl esters in the... 

Impressive progress has been made in stereospecific polymerization of cyclic ethers and cyclic esters since the first edition of CPS was published. A novel ROP phenomenon called stereocomplexation, which is especially important when it involves homochiral macromolecules, poly(R)- and poly(S)- polylactides, is analyzed in detail (chapter devoted to cyclic esters). A breakthrough in the stereoregulation of methyloxirane (propylene oxide) polymerization is the subject of a chapter on stereospecific polymerization of oxiranes. 

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