Styrene oxide production

A potent disclosure by Pechukas1821 describes the condensation of methyl chJorccarbonate in pyridine at 5 with ethylene oxide and propylene oxide, epichlorohydrio. and styrene oxide. Products formed... 

Yamamoto has reported that ytterbium triisopropoxide, prepared in situ from Yb(OTf)3 and LiOPr in THF, can be used in a very mild, highly efficient, and widely applicable procedure for the azidolysis of epoxides. In every case except styrene oxide, products are derived from the attack of azide at the less hindered carbon atom. The method appears to be quite tolerant of functionality, leaving preexisting tosyl, acyl, and siloxy groups intact (e.g.,... 

The ethene-oxidizing microorganism Mycobacterium strain NBB4 contains an ethylene monooxygenase, which have recently been used in the synthesis of stereo-complementary (l )-styrene oxide with 98% ee [110]. The reaction efficiency was enhanced in a biphasic system with styrene as the organic phase, but the enantioselectivity of the reaction decreased and yielded the oxides with 66-86% ee. The authors proposed a possible mechanism that a second, less stereoselective monooxygenase might be induced that also contributed to styrene oxide production. 

Sales demand for acetophenone is largely satisfied through distikative by-product recovery from residues produced in the Hock process for phenol (qv) manufacture. Acetophenone is produced in the Hock process by decomposition of cumene hydroperoxide. A more selective synthesis of acetophenone, by cleavage of cumene hydroperoxide over a cupric catalyst, has been patented (341). Acetophenone can also be produced by oxidizing the methylphenylcarbinol intermediate which is formed in styrene (qv) production processes using ethylbenzene oxidation, such as the ARCO and Halcon process and older technologies (342,343). 

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. 

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. 

Polystyrene was first made by E. Simon in 1839 who at the time believed he had produced an oxidation product, which he called styrol oxide. Since that time the polymerisation of styrene has been extensively studied. In fact a great deal of the work which now enables us to understand the fundamentals of polymerisation was carried out on styrene. 

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. 

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. 

Figure 5.8 Environmental factors E (top figure) and cost indices Cl (bottom figure) for the biocatalytic (a) and chemical catalytic (b) syntheses of (5)-styrene oxide (Scheme 5.3) including the synthesis of the Jacobsen catalyst and of the bacteria (Scheme 5.4) as further syntheses. Waste produced during biocatalyst synthesis is indicated. However, it has to be considered that biocatalyst and product synthesis cannot be separated.

Parrke, S., Held, M., Wubbolts, M.G., Witholt, B., Schmid, A. (2002) Pilot-Scale Production of (S)-Styrene Oxide from Styrene by Recombinant Escherichia coli Synthesizing Styrene Monooxygenase. Biotechnology and Bioengineering, 80, 33M1. 

An extraordinary way of stabilizing RUO2-coated CdS colloids for H2 generation was chosen by Fendler and co-workers The colloidal particles were generated in situ in surfactant vesicles of dioctadecyldimethylammonium chloride and dihexa-decyl phosphate. Thiophenol as a membrane permeable electron donor acted as a sacrificial additive. Later, a surface active re-usable electron donor (n-C,gH3,)2N — (CHj)—CH2—CHj—SH, Br was incorporated into the vesicles. Its R—SS—R oxidation product could be chemically reduced by NaBH to regenerate the active electron donor. The H2 yields in these systems were only 0.5 %. However, yields up to 10% were later reported for a system in which CdS was incorporated into a polymerizable styrene moiety, (n-C,jH3jC02(CH2)2) N (CH3) (CH2CgH4CH=CH2>, CP, and benzyl alcohol was used as the electron donor. 

Oxidation of organic compounds by dioxygen is a phenomenon of exceptional importance in nature, technology, and life. The liquid-phase oxidation of hydrocarbons forms the basis of several efficient technological synthetic processes such as the production of phenol via cumene oxidation, cyclohexanone from cyclohexane, styrene oxide from ethylbenzene, etc. The intensive development of oxidative petrochemical processes was observed in 1950-1970. Free radicals participate in the oxidation of organic compounds. Oxidation occurs very often as a chain reaction. Hydroperoxides are formed as intermediates and accelerate oxidation. The chemistry of the liquid-phase oxidation of organic compounds is closely interwoven with free radical chemistry, chemistry of peroxides, kinetics of chain reactions, and polymer chemistry. 

Miller and Mayo studied the styrene oxidation and came to conclusion that this chain reaction occurs via addition of peroxyl radical to double bond of styrene with formation of polyperoxide as a product A.A. Miller and F.R. Mayo [54]... 

The radiochemical oxidation of PS in a chloroform solution is accompanied by its destruction and formation of products of styrene oxidation, namely, benzaldehyde and styrene oxide [136]. The radiochemical yield of these products was equal to the radiochemical yield of PS macromolecule cleavages. Butyagin [137] analyzed the products of decomposition of the peroxyl radicals of PS and polyvinyIcyclohexane. Alkyl macroradicals were produced mechano- or photochemically, volatile products were evaporated in vacuum, and alkyl radicals were converted into peroxyl radicals using labeled lsO. Peroxyl radicals were then... 

Numerous enantioselective transfer hydrogenation processes have now been developed and operated at commercial scale to give consistent, high-quality products, economically. These include variously substituted aryl alcohols, styrene oxides and alicyclic and aliphatic amines. Those discussed in the public domain include (S)-3-trifluoromethylphenylethanol [48], (f )-3,5-bistrifluorophenylethanol [64], 3-nitrophenylethanol [92], (S)-4-fluorophenylethanol [lc], (f )-l-tetralol [lc], and (T)-l-methylnaphthylamine [lc]. 

Fig. 51. Correlation between the intensity of Ti-superoxo ([A + A] and [B + C]) signals and selectivity for styrene oxide and non-selective products in the styrene epoxidation reaction. The effects of titanosilicates, oxidants, and solvent on the correlation are depicted [from Srinivas et al. (52)].

The lithium perchlorate-catalysed aminolysis of styrene oxide has been investigated. Amines of low nucleophilicity, such as aromatic amines, give almost exclusively products of type 30, sterically hindered amines (diisopropylamine, dicyclohexylamine etc.) give... 

The styrene oxide (26 mmol) is added with stirring to acetylcobalt tetracarbonyl, obtained at room temperature by the addition of an excess of Mel (9.0 g, 64 mmol) to CTMA-Br (0.2 g, 0.55 mmol) and Co2(CO)8 (0.19 g, 0.55 mmol) under CO (1 atmos.). The mixture is stirred at room temperature for 12 h and the products are isolated using a work-up procedure analogous to that described in 8.2.6. 

The ODH of ethylbenzene to styrene is a highly promising alternative to the industrial process of non-oxidative dehydrogenation (DH). The main advantages are lower reaction temperatures of only 300 500 °C and the absence of a thermodynamic equilibrium. Coke formation is effectively reduced by working in an oxidative atmosphere, thus the presence of excess steam, which is the most expensive factor in industrial styrene synthesis, can be avoided. However, this process is still not commercialized so far due to insufficient styrene yields on the cost of unwanted hydrocarbon combustion to CO and C02, as well as the formation of styrene oxide, which is difficult to remove from the raw product. 

During the overall biotransformation, the product formation rate reached a maximum of 61 U g cells dry weight (CDW) and decreased to 27 U g CDW towards the end of the process. This resulted in a final product concentration of 306 him (5)-styrene oxide in the... 

For instance, styrene oxide was resolved by whole cells of Aspergillus niger and Beauveria bassiana via two different pathways showing matching enantio- and regioselectivities with excellent results (Scheme 8). Combination of the two biocatalysts employing a deracemization process in a single reactor led to R) phenylethane-l,2-diol as the sole product in 98% ee and 85% isolated yield [58]. 

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