Styrenes oxidative

Ethylenic compounds when oxidised with perbenzoic acid or perphthalic acid in chloroform solution yield epoxides (or oxiranes). This Is sometimes known as the Prileschajew epoxidation reaction. Thus pyrene affords styrene oxide (or 2-plienyloxirane) ... 

The use of epoxides as alkylating agents for diethyl malonate provides a useful route to y lactones Wnte equations illustrating such a sequence for styrene oxide as the starting epoxide Is the lactone formed by this reaction 3 phenylbutanohde or is it 4 phenylbutanohde ... 

Styrene undergoes many reactions of an unsaturated compound, such as addition, and of an aromatic compound, such as substitution (2,8). It reacts with various oxidising agents to form styrene oxide, ben2aldehyde, benzoic acid, and other oxygenated compounds. It reacts with benzene on an acidic catalyst to form diphenylethane. Further dehydrogenation of styrene to phenylacetylene is unfavorable even at the high temperature of 600°C, but a concentration of about 50 ppm of phenylacetylene is usually seen in the commercial styrene product. 

Catalytic hydrogenation of styrene oxide (86—99) is another process currendy used for the manufacture of PEA. The main requirements for this reaction are a low operating temperature to avoid side reactions and a good quaUty of styrene oxide [76-09-3] starting material. 

N-Unsubstituted pyrazoles and imidazoles add to unsaturated compounds in Michael reactions, for example acetylenecarboxylic esters and acrylonitrile readily form the expected addition products. Styrene oxide gives rise, for example, to 1-styrylimidazoles (76JCS(P1)545). Benzimidazole reacts with formaldehyde and secondary amines in the Mannich reaction to give 1-aminomethyl products. 

Styrene oxide [96-09-3] M 120.2, b 84-86 /16.5mm, d 1.053, n 1.535. Fractional distn at reduced pressure does not remove phenylacetaldehyde. If this material is present, the styrene oxide is treated with hydrogen under 3 atmospheres pressure in the presence of platinum oxide. The aldehyde, but not the oxide, is reduced to 6-phenylethanol) and separation is now readily achieved by fractional distn. [Schenck and Kaizermen J Am Chem Soc 75 1636 1953.]... 

Styrene oxide Sulphate Sulphite Sulprofos Sulphur dioxide Sulphur hexafluoride Sulphuric acid Sulphuryl fluoride Systox... 

Adduct 100 is formed from the 1,4 cycloaddition of o-quinone (99) with the morpholine enamine of cyclohexanone (125). Treatment of styrene oxide with cyclic enamines at elevated temperatures (about 230°C) produces O.N-ketals possessing a furan nucleus (125a). 

Condensation of normeperidine (81) with 3-chloropropan-l-ol affords the compound possessing the alcohol side chain (88). The hydroxyl is then converted to chlorine by means of thionyl chloride (89) displacement of the halogen by aniline yields pimino-dine (90). ° Condensation of the secondary amine, 81, with styrene oxide affords the alcohol, 91 removal of the benzyllic hydroxyl group by hydrogenolysis leads to pheneridlne (92). ... 

Trepipam (69) is a sedative agent apparendy acting via dopaminergic mechanisms. It can be synthesized by attack on the less hindered terminus of styrene oxide (66) by 4,5-dimethoxyphe-nethylamine (65) to give 67. Cyclodehydration catalyzed by strong acid then leads to 68 and N-... 

Hydrogenation of styrene oxide over palladium in methanol 66 gives exclusively 2-phenylethanol, but in buffered alkaline methanol the product is l-phenylelhanol. If alcoholysis of the epoxide by the product is troublesome, the problem can be eliminated by portion-wise addition of the epoxide to the reaction, so as always to maintain a high catalyst-to-substrate ratio. The technique is general for reactions in which the product can attack the starting material in competition with the hydrogenation. 

A mixture containing 186 g (0.20 mol) of 2-aminopyridine, 0.55 g of lithium amide and 75 cc of anhydrous toluene was refluxed for 1.5 hours. Styrene oxide (12.0 g = 0.10 mol) was then added to the reaction mixture with stirring over a period of ten minutes. The reaction mixture was stirred and refluxed for an additional 3.5 hours. A crystalline precipitate was formed during the reaction which was removed by filtration, MP 170°C to 171°C, 1.5 g. The filtrate was concentrated to dryness and a dark residue remained which was crystallized from anhydrous ether yield 6.0 g. Upon recrystallization of the crude solid from 30 cc of isopropyl alcohol, 2.0 g of a light yellow solid was isolated MP 170°C to 171°C. 

In an attempt to prepare sulfonium-ylide polymer, Tani-moto and coworkers [57,58] carried out the reaction of a sulfonium salt polymer with benzaldehyde in the presence of a base and obtained styrene oxide. The reaction was considered to process via a ylide polymer formation (Scheme 24), which may be unstable and has not been isolated. 

If the styrene oxide is distilled over a free flame some... 

Styrene oxide has previously been prepared by the action of iodine, water and mercuric oxide on styrene.1 A description of Hibbert s method 2 using benzoylhydroperoxide has appeared... 

Styrene, 8, 84,102 Styrene oxide, 8,102 Sublimation under reduced pressure, 6, 80... 

Unfortunately, the highest enantioselectivity so far obtained for the synthesis of styrene oxide by this route is only 57 % ee with Goodman s sulfide 30 [21]. Thus methylidene transfer is not yet an effective strategy for the synthesis of terminal epoxides. 

Florio et al. demonstrated that the lithiation/electrophile trapping of enantio-pure styrene oxide, as well as the (3-substituted styrene oxides 180 and 182, is totally stereoselective (Scheme 5.42) [66]. These results demonstrate that the intermediate benzylic anions are configurationally stable within the timescale of depro-tonation/electrophile trapping. 

A major limitation of this method is the low pH at which the reactions are performed, which resulted in substantially lower yields in reactions with substrate progenitors of acid-sensitive epoxides, in which competing ring-opening processes effectively reduced the usefulness of the method. As an example, the oxidation of styrene had proceeded with 70% conversion after 3 h at 70 °C, but the observed yield of styrene oxide was only 2% (Table 6.5, Entry 5). 

Bartoli recently discovered that by switching from azide to p-anisidine as nucleophile, the ARO of racemic trans- 3-substituted styrene oxides could be catalyzed by the (salen)Cr-Cl complex 2 with complete regioselectivity and moderate selectivity factors (Scheme 7.36) [14]. The ability to access anti-P-amino alcohols nicely complements the existing methods for the preparation of syn-aryl isoserines and related compounds [67] by asymmetric oxidation of trans-cinnamate derivatives [68]. 

Optically pure (S)-benzyl methyl sulfoxide 139 can be converted to the corresponding a-lithio-derivative, which upon reaction with acetone gave a diastereomeric mixture (15 1) of the /S-hydroxysulfoxide 140. This addition reaction gave preferentially the product in which the configuration of the original carbanion is maintained. By this reaction, an optically active epoxy compound 142 was prepared from the cyclohexanone adduct 141181. Johnson and Schroeck188,189 succeeded in obtaining optically active styrene oxide by recrystallization of the condensation product of (+ )-(S)-n-butyl methyl sulfoxide 143 with benzaldehyde. 

Styrene glycol is available from Aldrich Chemical Company, Inc. or from Eastman Organic Chemicals. Alternatively, it may be prepared by hydrolysis of styrene oxide.3 If the glycol melts at lower than 63°, it should be recrystallized before use. 

Furstoss et al. have reported their studies on the use of an epoxide hydrolase with four styrene oxide derivatives (Figure 5.26) [39]. The (R)-diol (43) was obtained in 91% ee at 100% conversion from racemic (42), demonstrating an enantioconvergent... 

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