Styrene Production after

Invented in Germany during World War II by H. Hock and S. Lang in the course of developing cumene hydroperoxide for initiating the polymerization of butadiene-styrene mixtures. After the war the process was developed by the Distillers Company in England and Allied Chemical Corporation in the United States. Since 1954 this has been the main commercial process for the production of phenol and acetone. By 1987, 97 percent of the phenol made in the United States was produced via this route. In 1990, both resorcinol and hydro-quinone were produced commercially by this route as well. See also Cumox. 

After styrene production, approximately 20% of benzene production is used to produce cumene (isopropylbenzene), which is converted to phenol and acetone. Benzene is also converted to cyclohexane, which is used to produce nylon and synthetic fibers. Nitrobenzene derived from benzene is used to produce aniline, which has widespread use in dye production. Besides the benzene derivatives mentioned in this section, countless other products are based on the benzene ring. Cosmetics, drugs, pesticides, and petroleum products are just a few... 

Figure 19.13 shows the dynamic mechanical properties of such a blend of sPS with a mixture of Kraton G 1651 (15 %) and microsuspension rubber particles (20%) consisting of 60% butyl acrylate (BA) core grafted with 40% styrene shell (S//BA). The glass transition temperatures of the Kraton (-60 °C) and the butyl acrylate (-45 °C) phases can be easily distinguished from one another. The TEM image of such a product after deformation is shown in Figure 19.14. The annealed specimen is shown since the two rubber types are better discernible than in the nonannealed sample. As expected, crazing and voiding in the rubber particles dominate. The product had the following notched impact strengths (ISO 179/eA) injection moulded (80 °C mould temperature) 6.3, injection moulded (140 °C) 4.0 and annealed 3.7kJ/m2.

The development of the Ziegler-Natta catalysts has affected rubber production as well. Eirst, it facilitated the synthesis of all-c/s polyisoprene and the demonstration that its properties were nearly identical to those of natural rubber. (A small amount of synthetic natural rubber is produced today.) Second, a new kind of synthetic rubber was developed all-c/s polybutadiene. It now ranks second in production after styrene-butadiene rubber. 

The exit stream is condensed and, after addition of a polymerization inhibitor (usually sulfur), is successively distilled under reduced pressure to a styrene purity of better than 99.7%. A few ppm of 4-t-butylcatechol inhibitor is added to the purified product after which it is ready to be shipped. Industrial yield (selectively) of styrene from ethylbenzene is about 90%. 

The fate of diazirines on decomposition can be influenced by the addition of y -cyclodextrin (j6-CD). When 3-methyl-3-phenyl-3jf/-diazirine (3) was thermolyzed under argon, 1 -methyl-1,2-diphenylcyclopropane (4) was obtained as an isomeric mixture in close to 20% yield the main product (43% yield) was acetophenone azine (5). Cyclodextrin complexation prior to pyrolysis, however, increased the yield of 4 tremendously. The carbohydrate, therefore, facilitates both styrene (6) and cyclopropane formation.It is also interesting to note that the trans-41 cis-4 ratio increased concomitantly and that styrene appears as an isolable product after photochemical, but not after thermal degradation of the 3 /(-CD complex. 

Rh(sulphos)(cod)] (1 500 catalyst/substrate ratio). The hydrogen pressure was 3 MPa, and the temperature was 65 °C. After 3 h a conversion of more than 90% was obtained and complete disappearance of styrene occurred after a further 2 h of reaction. After cooling the reaction mixture to room temperature, separation of the two phases did not give complete organic product separation, whereas the rhodium catalyst remained in the alcohol phase. Simple addition of water resulted in complete elimination of ethylbenzene (and residual styrene) from the alcohol phase. Remarkable, the catalytic activity of [Rh(sulphos(cod)] in the biphasic system is the same as in pure methanol, indicating that at the reaction temperature a homogeneous phase is formed. 

The beneficial application of ultrasound was also demonstrated in the application of immobilized aryl halides. The air- and water-stable Merryfield-type resins could be reused without loss of activity [ 193]. A variety of olefins (e.g. styrene) were reacted to the expected products after cleavage from the resin in yields of up to 81% (purity >90%). 

Of far-reaching and more lasting importance for the industrial use of benzene was the commencement of the production of styrene by IG Farbenindustrie in 1929, and the hydrogenation of benzene to cyclohexane as a feedstock for nylon production, after the discovery of nylon synthesis from hexamethylenediamine and adipic acid by Wallace H.Carothers of Du Pont in 1935. 

After the reaction between the epoxy resin and the acid has been completed, styrene and additives are added to obtain the required characteristics of the finished product. After the dissolution in the styrene, the temperature of the mass has to be quickly lowered to below 30 °C to prevent the product curing. 

C, and styrene production was also more by 11 wt% in the case of waste expanded polystyrene. Oil yield increased from 24 to 98 wt% with increase in reaction temperature from 350 to 480 °C, while styrene selectivity, which was about 76 wt% up to 450 °C, decreased sharply to 49 wt% at 480 °C. This decrease in styrene selectivity takes place with increase in styrene dimer formation from 4 to 10 wt% and production of other chemicals. Also the production of toluene, ethylbenzene and methylstyrene decreased with the same rise in pyrolysis temperature. Thermal degradation of PS was reported to have started with random initiation to form polymer radicals, the main products being styrene and its corresponding dimers and trimers. These results were comparable with studies reported elsewhere on oil yield of 99 wt% with 60 wt% styrene monomer and 25 wt% for other aromatics. Another work has reported on recovery of 58 wt% styrene from thermal degradation of PS at 350 °C after a time of 60 min [a.379]. Furthermore, oil yields of 82 wt% with 70 wt% styrene selectivity and 77 wt% styrene recovery at 580 °C have been reported [a.380]. 

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