Methyloxirane reaction

Propylene oxide [75-56-9] (methyloxirane, 1,2-epoxypropane) is a significant organic chemical used primarily as a reaction intermediate for production of polyether polyols, propylene glycol, alkanolamines (qv), glycol ethers, and many other useful products (see Glycols). Propylene oxide was first prepared in 1861 by Oser and first polymerized by Levene and Walti in 1927 (1). Propylene oxide is manufactured by two basic processes the traditional chlorohydrin process (see Chlorohydrins) and the hydroperoxide process, where either / fZ-butanol (see Butyl alcohols) or styrene (qv) is a co-product. Research continues in an effort to develop a direct oxidation process to be used commercially. 

Lewis acid SnCLj-assisted reaction between the l,3-thiazole-5-thione 434 and /ra r-2,3-dimethyloxirane led to the m 4,5-dimethyl-l,3-oxathiolane 435 The same Lewis acid enabled a second addition of /ra/ -2,3-dimcthyloxirane onto the C—N bond of the 1,3-thiazole ting of 434, leading to the formation of the tetrahydro-2//-thiazolo[2,3- ]-oxazole adduct 436 (Equation 200) <2000HCA3163>. Condensation of 2,4-dinitroimidazole, 8-bromotheophylline, and 8-bromoadenine with substituted methyloxiranes involved sequential A -alkylation-r/wo-substitution and furnished a series of 2,3-dihydro-imidazo[2,l- ]oxazole derivatives 437, 438, and 439 (Equations 201-203) <2000CCC1126, 2000EJ03489, 2005TL3561, 2004JHC51>. 

A novel aromatic substitution reaction with electron-deficient radicals, which avoids the use of stannanes, is promoted by the addition of tetra-n-butylammonium bromide [54]. Iodoacetonitrile and iodoacetic esters react with pyrroles and indoles in good to high yield upon photolysis in the presence of 2-methyloxirane and sodium thiosulphate (Scheme 6.34). 

A mixture of the cell suspension (2.2 mL), glycerol (0.67 mL) and (S)-l-benzylox-ymethyl-1-methyloxirane (0.50 g, 2.81 mmol) was stirred at room temperature. The progress of the actual enzymatic reaction was monitored occasionally by HPLC as described in Section 5.6.3.2, step 4. 

Polymerization in which a tactic polymer is formed. However, polymerization in which stereoisomerism present in the monomer is merely retained in the polymer is not to be regarded as stereospecific. For example, the polymerization of a chiral monomer, e.g., R)-propylene oxide ((i )-methyloxirane), with retention of configuration is not considered to be a stereospecific reaction however, selective polymerization, with retention, of one of the enantiomers present in a mixture of R)- and (S)-propylene oxide molecules is so classified. 

When simple aliphatic epoxides such as methyloxirane react with hydrogen halides, the dominant mode of reaction introduces halide at the less substituted primary carbon.88... 

Cyclic carbonates. Reaction with MoCl5-(C6H5)3P (1 6) allows the insertion of C02 into methyloxirane to proceed at 20° and 1 atm. This reaction had been... 

A detailed study271 on the reaction of 2,3-dimethyl-2-butene with ozone revealed that epoxide formation strongly depends on alkene concentration and temperature. Under appropiate reaction conditions (neat alkene, 0°C) the corresponding tetra-methyloxirane was the main product. Dimethyldioxirane formed from energy-rich acetone oxide (a cleavage product of the alkene) was postulated to be responsible for epoxidation. 

The data in Table 1 show that the transformation of methyloxirane is a structure-sensitive reaction, since the total turnover frequency (TOF) in the transformation of methyloxirane varies appreciably with increasing dispersion. The rate of transformation passes through a maximum as a function of dispersion. Since the theoretical calculations of van Hardeveld and Hartog (ref. 12) indicate that the number of step sites changes via a maximum curve as a function of the dispersion, this maximum curve may be an indication that... 

The same Pt/SiC catalysts were poisoned by CS2 the hydrogenation of (+)-apopinene was used as an indicator reaction (ref. 14). The amount of CS2 necessary to eliminate the hydrogenation activity permits calculation of the fraction of metal sites active in olefin hydrogenation. This fraction correlates with the number of step sites. Similarly, a good correlation is found between this fraction and the rate of methyloxirane transformation (Table 1). These results reveal that the structure-sensitivity is caused by the variation in the number of active sites, and the steps appear to be the active sites for the regioselective hydrogenation of methyloxirane. 

The transformation of methyloxirane on various Pt catalysts is a structure-sensitive reaction. The total TOF of the reaction exhibits a maximum curve as a function of dispersion. The structure sensitivity is caused by the change in the number of active sites. 

The hydrogenolysis and isomerization of methyloxirane take place via a mechanism in which hydrogen is involved in the rate-determining step. This reaction occurs on the step sites. 

Takeda and coworkers showed that the reaction of a silylmethyllithium with a halo-methyloxirane gave the corresponding cyclobutane derivatives via a 1,4-silyl migration of the initial lithium alkoxide followed by an intramolecular nucleophilic substitution of the resulting carbanion (equation 151)370. 

Turning to current work employing gold catalysts, the reaction that has attracted most attention is the oxidation of propene to methyloxirane (propene oxide or 1,2-epoxypropane).2 While silver catalysts work very well for epoxidising ethene, they fail utterly with propene, because the selective intermediate is more reactive than the reactant, and carbon dioxide alone... 

Initial addition reaction of methyloxirane to 4-methyl-l-oxa-4-azaspiro[4.5]decane 164 is followed by ring expansion under thermal conditions. O-Nucleophilic attack is directed on quaternary carbon of the spiro system rather than on C-4 carbon of the oxazolidine ring, and 8,10-dimethyl-7,13-dioxa-10-azaspiro[5.7]tridecane 165 is a major product of the transformation (Scheme 42 <1995IZV1838>). 

The reaction of 4,4 -dimethoxythiobenzophenone with (A)-2-methyloxirane in the presence of ZnCl2 leads to the corresponding 1 1 adduct, that is, 1,3-oxathiolane 177. A 1 2 adduct, (46,86 )-l,3,6-dioxathiocane 14, was formed as a minor product. Treatment of the mixture of 1 1 adduct and (A)-2-methyloxirane with BF3 etherate gives the 1 2 adduct 14 in low yield (Scheme 47 <2001HCA3319, 2003HCA2833 . 

Deprotonation of indoles 128 followed by alkylation with 2-methyloxirane led to the secondary alcohols 129 that were used as starting compounds in the preparation of substituted 2-(l//-indol-l-yl)-l-methylethylamines 130, novel agonists of 5HT2C receptors. Sn2 reaction of the corresponding mesylates with sodium azide and reduction of the azides with either hydrogen or LiAlH4 produced amines 130 in excellent yields (Scheme 28) <1997JME2762>. 

Reaction of ethyl iodoacetate with an excess (5 equiv) of pyrrole in the presence of 2-methyloxirane and BusSnSnBus led to the desired substitution product 1011 in 43% yield, in addition to an undetermined quantity of ethyl phenyl-acetate 1012 (Equation 239), indicating reactivity with the benzene solvent under the reaction conditions <1999TL2677>. The less toxic solvent, methyD-butyl ether (MTBE), provided product 1011 in improved (64%) yield. 

Sokolskii et al. [233] noticed that ZN coordination centres spontaneously change to cationic centres during polymerization. In our laboratory we have attempted to obtain quantitative data on a similar reaction by means of models [232], Tsuchyia and Tsuruta [234] pointed out the possibility of choice between anionic and cationic polymerization of methyloxirane with diethylzinc —HzO (see Chap. 3, Sect. 2.1). 

The ratio of back- and end-biting reactions depends on the reaction conditions, and may differ considerably in polymerizations of various monomers. In cationic polymerization, methyloxirane produces mainly a mixture of cyclic tetramers [335] and chloromethyloxirane yields both dimers and tetramers [336]. Under similar conditions, 1,3-dioxolane or 1,3-dioxepane yield a number of cyclic derivatives [337], the distribution of cyclics being in agreement with the Jacobson-Stockmayer theory [338],... 

Tire reaction of carbon dioxide, hydrogen and methyloxirane Iras been desenbed by Koiiiunra (173, 174]. I, 2 Propanedtol formates were prepared in the presence of iri (triphenylphosphine)chlororhodium or tris (tripheny I phosphine) dichlororutheniunr as catalysts. No cocatalysl is required. 

The prototype for this structural class is 2-methyl-2-propen-l-ol (methallyl alcohol) firom which asymmetric epoxidation generates optically active 2-methyloxiranemethanol. Like glycidol, 2-methyloxirane-methanol has been difficult to obtain by stoichiometric asymmetric epoxidation, but with the use of the catalytic version reasonable quantities now are produced and the compound has become commercially available. In situ derivatization also can be used to recover this epoxy alcohol from the epoxidation reaction. Progress in the isolation of 2-methyloxiranemethanol is reflected in entries 1-3 of Table 3, and... 

Cyclododecanone has been synthesized from epoxycyclododecane on a Pd catalyst.Comprehensive work has been carried out on the hydrogenolysis and isomerization of methyloxirane on various metals. The results have been compared with those for oxacycloalkanes with larger rings.The transformations of 1,1-dimethyloxirane and 1-methylepoxycyclopentene have been followed on Pd, Pt, Rh, Cu, and Ni catalysts. The mechanisms of the catalytic reactions have been dealt with in detail. It has been demonstrated that the isomerization of the oxiranes on metals is the primary process, occurring in parallel with hydrogenolysis. The pathway of the reaction depends on the nature of the metal. Deuteration has been utilized to establish the role of hydrogen. 

The results of solvolysis in acidic medium in comprehensive examination of methyloxirane, phenyloxirane, and their derivatives have been interpreted on the basis of activity parameters,Studies on the reactions of methyloxirane, 1,1-dimethyloxirane, and epichlorohydrin have led to the proposal of a new mechanism, denoted From research on dimethyloxirane in aqueous and non-... 

The great variety of transformations that can occur with other sulfur-containing nucleophiles are illustrated by the following experimental observations. Oxiranes react with sulfurated borohydrides in a similar way as the hydrogen sulfide in a basic medium symmetric bis hydroxyethyl disulfides are formed. c/s-benzene trioxide gives di- and triadducts with A, A-diphenylthiocarbamide. Reports have appeared on the reactions between oxirane and -decylmercaptan, butadiene-monooxirane derivatives and mercaptans, and methyloxirane and sulfite ion. ... 

A comprehensive study has been made of the kinetics of the reaction of oxiranes and amines, with special regard to the side-reactions and the role of the secondary products.The reaction of methyloxirane and dibutylamine has been investigated in an aprotic solvent to acquire information on the orientation of the ring scission.Some kinetic studies relating to this field are also worth of men-... 

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