Styrene benzene system

The butyllithium-styrene-benzene system is the only one to the present time in which it has been possible to carry out such a detailed... 

Mixed dimerization also affects the kinetics of anionic copolymerization of styrene and para-methyl styrene, a system studied by O Driscoll(24). The reaction was performed in benzene with lithium counter-ions and the plots of In.[styrene] or In(para-methyl styrene] vs. time were both linear. Their slopes,... 

Recently it was found possible (10) actually to determine the value of Ke from physical measurements, and Equation 2 could be resolved for the two systems—isoprene (hexane) (10) and styrene (benzene). Typical data obtained in the latter system are shown in Table I. By measuring Ke at different temperatures, it is possible to determine the actual concentration of active species,... 

As shown In Figure 4, the rate of polymerization of styrene was retarded by good nonvlscous solvents such as benzene, cyclohexane, and octane whose solubility parameters (6) were within 1.5H of that of polystyrene at styrene to additive ratios of 3 to 1. The absolute rates were slightly Increased In poorer nonvlscous solvents such as heptane and hexane and were fastest In viscous nonsolvents such as dllsoctyl phthalate and Nujol. Rate studies Indicated a Rp dependency on [E] substantially greater than unity for the styrene emulsion systems modified with viscous poor solvents. 

Lovley, D.R., Anaerobic benzene degradation, Biodegradation 11, 107—116, 2000 Snyder, R., Xenobiotic metabolism and the mechanism(s) of benzene toxicity. Drug Metab. Rev. 36, 531—547, 2004 Rana, S.V. and Verma, Y., Biochemical toxicity of benzene, J. Environ. Biol. 26,157—168, 2005 Lin, Y.S., McKelvey, W., Waidyanatha, S., and Rappaport, S.M., Variability of albumin adducts of 1,4-benzoquinone, a toxic metabolite of benzene, in human volunteers. Biomarkers 11,14-27, 2006 Baron, M. and Kowalewski, V.J., The liquid water-benzene system, J. Phys. Chem. A Mol. Spectrosc. Kinet. Environ. Gen. Theory 100, 7122-7129, 2006 Chambers, D.M., McElprang, D.O., Waterhouse, M.G., and Blount, B.C., An improved approach for accurate quantiation of benzene, toluene, ethylbenzene, zylene, and styrene in blood, Anal. Chem. 78, 5375-5383, 2006. 

Design a reactor system to produce styrene by the vapor-phase catalytic dehydrogenation of ethyl benzene. The reaction is endothermic, so that elevated temperatures are necessary to obtain reasonable conversions. The plant capacity is to be 20 tons of crude styrene (styrene, benzene, and toluene) per day. Determine the bulk volume of catalyst and number of tubes in the reactor by the one-dimensional method. Assume that two reactors will be needed for continuous production of 20 tons/day, with one reactor in operation while the catalyst is being regenerated in the other. Also determine the composition of the crude styrene product. 

Reynolds and co-workers (61,62,95-100) have used ab initio and other theoretical and nmr chemical shift data to examine substituent effects in substituted benzenes. Systems studied in this way include substituted benzoic acids (61), styrenes (62,98), phenylacetylenes (99), and phenylalkanes (96). Particular emphasis has been placed on the separation of field, inductive, and resonance effects. 

In the St. Clair River Area of Concern, Dow Chemical Canada, Inc. of Sarnia, Ontario has expanded the process water collection system at its EB/Styrene plant to maximize the recovery of organic compounds. The EB/Styrene plant uses ethyl benzene, styrene, benzene, and toluene in the production of more complex organic compounds. During the manufacturing process, these four compounds end up in the wastewater. The wastewater collection system has been expanded recently to recover all process wastewater and divert it to the purification tower where these four contaminants are steam stripped out and then reused as part of the fuel stream to produce steam and electricity (P. Murphy, pers. comm., Dow Chem. Can. Inc., Sarnia, Ontario, 1989). This project was implemented in 1986 at a cost of 270,000. The tower removes approximately 250 kg/d of contaminants (Mackinnon 1989) which are then added to other fuel streams providing a savings in displaced fuel cost of approximately 20,000 per year (P. Murphy, pers. comm., Dow Chem. Can. Inc., Sarnia, Ontario, 1989). 

W. Trochimezuk, Changes in Structure of Polyethylene/Styrene divinyl benzene System, presented at the Structure and Properties of Polymer Networks, Jablonna, Poland, April 1979. Polyethylene/poly(styrene-co-divinyl benzene) semi-II IPNs. Scanning electron microscopy of etched samples. Morphology goes from PS discontinuous to PS continuous as DVB level is increased passed 2%. Polyethylene crystal size is decreased with increasing DVB content. 

W. Trochimezuk, Polyethylene-Poly(styrene-co-divinyl benzene) System. II. Swelling and Specific Volume Measurements, Presented at the lUPAC Sponsored Conference,... 

Rhenium oxides have been studied as catalyst materials in oxidation reactions of sulfur dioxide to sulfur trioxide, sulfite to sulfate, and nitrite to nitrate. There has been no commercial development in this area. These compounds have also been used as catalysts for reductions, but appear not to have exceptional properties. Rhenium sulfide catalysts have been used for hydrogenations of organic compounds, including benzene and styrene, and for dehydrogenation of alcohols to give aldehydes (qv) and ketones (qv). The significant property of these catalyst systems is that they are not poisoned by sulfur compounds. 

Figure 5 illustrates a typical distillation train in a styrene plant. Benzene and toluene by-products are recovered in the overhead of the benzene—toluene column. The bottoms from the benzene—toluene column are distilled in the ethylbenzene recycle column, where the separation of ethylbenzene and styrene is effected. The ethylbenzene, containing up to 3% styrene, is taken overhead and recycled to the dehydrogenation section. The bottoms, which contain styrene, by-products heavier than styrene, polymers, inhibitor, and up to 1000 ppm ethylbenzene, are pumped to the styrene finishing column. The overhead product from this column is purified styrene. The bottoms are further processed in a residue-finishing system to recover additional styrene from the residue, which consists of heavy by-products, polymers, and inhibitor. The residue is used as fuel. The residue-finishing system can be a flash evaporator or a small distillation column. This distillation sequence is used in the Fina-Badger process and the Dow process. 

Styrene. Commercial manufacture of this commodity monomer depends on ethylbenzene, which is converted by several means to a low purity styrene, subsequendy distilled to the pure form. A small percentage of styrene is made from the oxidative process, whereby ethylbenzene is oxidized to a hydroperoxide or alcohol and then dehydrated to styrene. A popular commercial route has been the alkylation of benzene to ethylbenzene, with ethylene, after which the cmde ethylbenzene is distilled to give high purity ethylbenzene. The ethylbenzene is direcdy dehydrogenated to styrene monomer in the vapor phase with steam and appropriate catalysts. Most styrene is manufactured by variations of this process. A variety of catalyst systems are used, based on ferric oxide with other components, including potassium salts, which improve the catalytic activity (10). 

The bulk of commercial styrene is prepared by the Dow process or some similar system. The method involves the reaction of benzene and ethylene to ethylbenzene, its dehydrogenation to styrene and a final finishing stage. It is therefore useful to consider this process in each of the three stages. 

The initiation of polymerization of styrene and isoprene in benzene by t-butyl lithium reveals some complexities129) (e.g. zero order kinetics in monomer) not observed in the reaction proceeding in cyclohexane. Further studies of that system are needed. 

Harano and colleagues [48] found that the reactivity of the Diels-Alder reaction of cyclopentadienones with unactivated olefins is enhanced in phenolic solvents. Scheme 6.28 gives some examples of the cycloadditions of 2,5-bis-(methoxycar-bonyl)-3,4-diphenylcyclopentadienone 45 with styrene and cyclohexene in p-chlorophenol (PCP). Notice the result of the cycloaddition of cyclohexene which is known to be a very unreactive dienophile in PCP at 80 °C the reaction works, while no Diels-Alder adduct was obtained in benzene. PCP also favors the decarbonylation of the adduct, generating a new conjugated dienic system, and therefore a subsequent Diels-Alder reaction is possible. Thus, the thermolysis at 170 °C for 10 h of Diels-Alder adduct 47, which comes from the cycloaddition of 45 with 1,5-octadiene 46 (Scheme 6.29), gives the multiple Diels-Alder adduct 49 via decarbonylated adduct 48. In PCP, the reaction occurs at a temperature about 50 °C lower than when performed without solvent, and product 49 is obtained by a one-pot procedure in good yield. 

Betzemeier et al. (1998) have used f-BuOOH, in the presence of a Pd(II) catalyst bearing perfluorinated ligands using a biphasic system of benzene and bromo perfluoro octane to convert a variety of olefins, such as styrene, p-substituted styrenes, vinyl naphthalene, 1-decene etc. to the corresponding ketone via a Wacker type process. Xia and Fell (1997) have used the Li salt of triphenylphosphine monosulphonic acid, which can be solubilized with methanol. A hydroformylation reaction is conducted and catalyst recovery is facilitated by removal of methanol when filtration or extraction with water can be practised. The aqueous solution can be evaporated and the solid salt can be dissolved in methanol and recycled. 

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