Styrene and aromatic hydrocarbons

Styrene is not only used as a monomer in the production of polystyrene but also as a reactive solvent in the manufacture of unsaturated polyester resins. The hepatic metabolism of styrene involves the formation of the reactive intermediate styrene 7,8-oxide. In rat models, styrene 7,8-oxide binds to hepatic macromolecules and lipids causing hepatocellular in- 

David K. Bonauto, C. Andrew Brodkin, William O. Robertson 

Toluene, benzene and xylenes are generally eonsidered to have limited hepatotoxieity. Exposure to xylene is reported to eause mild steatosis. Exposure to a mixture of solvents, inelusive of xylene and toluene have been reported to produce elevated serum bile aeids.  

Epidemiologic investigations of workers exposed to high concentrations (greater than 50 ppm) of styrene have shown elevations in GGT, AST, and serum biliru- 

---

Jackson and Walker [7] studied the applicability of pyrolysis combined with capillary column GC to the examination of phenyl polymers (e.g., styrene-isoprene copolymer) and phenyl ethers e.g., bis[w-(w-phenoxy phenoxy)phenyl]ether. In the procedure the polymer sample is dissolved in benzene. The pyrolysis Curie point temperature wire is dipped 6 mm into the polymer solution. The polymer-coated wires are then placed in a vacuum oven at 75-80 °C for 30 minutes to remove the solvent. Figure 6.2 shows a characteristic pyrogram of the copolymer (isoprene-styrene) resulting from a 10-second pyrolysis at 601 °C. When the polyisoprene is pyrolysed, C2, C3, C4, isoprene, and CjoHig dimers are produced. When PS is pyrolysed, styrene and aromatic hydrocarbons are the products. Figure 6.2 shows that the copolymer product distribution and relative area basis resemble the two individual polymer product distributions. 

A pyrogram of the copolymer (isoprene-styrene) resulting from a 10 s pyrolysis at 601°C yields product distributions similar to the sum of the two constituent product distributions. For example, when the polymer polyisoprene is pyrolyzed, C2, C3, C4, isoprene and Cjo dimers are produced. When polystyrene is pyrolyzed, styrene and aromatic hydrocarbons are the products. The copolymer product distribution and relative area basis resemble the two individual polymer product distributions. 

The first resins to be produced on a commercial scale were the coumarone—indene or coal-tar resins (1) production in the United States was started before 1920. These resins were dominant until the development of petroleum resins, which were estabHshed as important raw materials by the mid-1940s. Continued development of petroleum-based resins has led to a wide variety of aHphatic, cyclodiene, and aromatic hydrocarbon-based resins. The principal components of petroleum resins are based on piperylenes, dicyclopentadiene (DCPD), styrene, indene, and their respective alkylated derivatives. 

More than half of approximately 200 employees working with composite plastic materials in the building of an aircraft manufacturing plant reported CNS, respiratory, heart, and gastrointestinal symptoms. Phenol (1.46), formaldehyde (0.35), styrene (2.95), methylene chloride (1.25), methanol (-0.77), as well as several lipophilic aliphatic and aromatic hydrocarbons were found in the air of the building. All exposures were at levels below PEL)24... 

Properties Clear, water-white liquid. D 0.791 (25/ 25C), fp -40C, bp 111C, refr index 1.389 (20C), flash p 65F (18.3C) (CC). Soluble in styrene, ketones, most aliphatic and aromatic hydrocarbons insoluble in water. 

Many chemicals can be made from two or more building blocks. For example, styrene can be made from two building blocks of ethylene and aromatic hydrocarbons. 

The controlled oxygenation of alkanes, alkenes, and aromatic hydrocarbons is one of the most important technologies for the conversion of crude oil and natural gas to valuable commodity chemicals. Biomimetic studies of metalloporpltyrins have led to important advances in practical catalysis, especially with ruthenium porphyrins. Reaction of wj-CPBA, periodate, or iodosylbenzene with Ru(II)(TMP)(CO) produced RuCVIjfTMPXOjj . Remarkably, Ru(VI)(TMP)(0)2 was found to catalyze the aerobic epoxidation of olefins under mild conditions. Thus, for a number of olefins including cyclooctene, norbomene, cis-, and trans- -methyl styrene 16-45 equivalents of epoxide were... 

Soluble Polystyrene. Styrene homopolymers (generally in admixture with other binders) are used in special applications such as zinc dust primers and bronze lacquers, in paints for mineral substrates and paper, as well as in adhesives. Polystyrene and poly(a-methylstyrene) have good water resistance, low permeability, resistance to chemicals and light, and also dry quickly. Suitable solvents include aliphatic and aromatic hydrocarbons, in some cases containing ketones or esters. 

The solvency of cycloaliphatic hydrocarbons is between that of aliphatic and aromatic hydrocarbons. They have a high solvency for fats, oils, oil-modified alkyd resins, styrene-modified oils and alkyd resins, bitumen, rubber, and other polymers. Polar resins (e.g., urea-, melamine-, and phenol-formaldehyde resins), as well as alcohol-soluble synthetic resins and cellulose esters are, however, insoluble. 

Polystyrene-supported iodosylbenzene (22) (loading of -lO groups up to 1.50 mmol g" ) has been prepared by a solvent-free reaction of poly[(diacetoxyiodo)styrene] (4) with sodium hydroxide (Scheme 5.11) [22]. Elemental analysis of polymer 22 indicates that the -lO groups are partially hydrated as shown in structure 23. This resin has been successfully used for efficient oxidation of a diverse collection of alcohols to aldehydes and ketones in the presence of BF3-Et20. Reagent 22 can also be employed as efficient co-catalyst in combination with RuCls in the catalytic oxidation of alcohols and aromatic hydrocarbons, respectively, to the corresponding carboxylic acids and ketones using Oxone as the stoichiometric oxidant [22]. 

Dietiker and Chen investigated the reaction of iridium complexes [(PHOX)IrL] (PHOX = chiral phosphanylox-azoline, L = H2, styrene) toward aromatic hydrocarbons. [(PHOX)IrH2] was generated by electrospray and reacted with ethylbenzene, affording [(PHOX)Ir(PhEt)] in the gas phase. This complex readily loses H2 upon collision with Ar, and [(PHOX)Ir(styrene)] is formed. In the reverse experiment, [(PHOX)Ir(styrene)] was... 

Rare-earth complexes of porphyrins also show catalytic activity in the radical oxidation of unsaturated hydrocarbons by various oxidizing agents such as potassium hydrochlorite and tezt-butyl hydroperoxide (Knchnev et al. 1991). Styrene, for example, undergoes oxidation to give a mixture of the aldehydes PhCHO and PhCH2CHO, and the epoxide PhCHCH20. The oxidation of saturated and aromatic hydrocarbons is also promoted by... 

Classification Organic peroxide Empirical C8H18O2 Formula (CH3)3COOC(CH3)3 Properties Clear water-wh. liq. distinctive odor sol. in styrene, ketones, ethanol, most resin monomers, most aliphatic and aromatic hydrocarbons pract. insol. in water m.w. 146.23 dens. 0.791 (25/25 C) vapor pressure 19.51 mm (20 C) f.p. -40 C b.p. Ill C dec. 190C flash... 

The similarity in chemical structure to isoprene explains why these are quite compatible with natural rubber and synthetic isoprene-based polymers (or block copoljuners). The C-9 aromatic hydrocarbon resins include indene- and styrene-based oligomers. Because of the difference in chemical structure these will associate with the end-blocks in S-I-S copolymers, and thus have a reinforcing effect and improve high temperature performance. Finally, mixtures of aliphatic and aromatic hydrocarbon resins are commonly used as a way to tailor compatibility and physical properties of the resultant PSAs. 

Another metallocene, namely, decamethylosmocene, (Mc5C5)20s (catalyst 1.2), turned out to be a good precatalyst in a very efficient oxidation of alkanes with hydrogen peroxide in acetonitrile at 20 — 60 °C [9]. The reaction proceeds with a substantial lag period that can be reduced by the addition of pyridine in a small concentration. Alkanes, RH, are oxidized primarily to the corresponding alkyl hydroperoxides, ROOH. TONs attain 51,000 in the case of cyclohexane (maximum turnover frequency was 6000 h ) and 3600 in the case of ethane. The oxidation of benzene and styrene afforded phenol and benzaldehyde, respectively. A kinetic study of cyclohexane oxidation catalyzed by 1.2 and selectivity parameters (measured in the oxidation of n-heptane, methylcyclohexane, isooctane, c -dimethylcyclohexane, and trans-dimethylcyclohexane) indicated that the oxidation of saturated, olefinic, and aromatic hydrocarbons proceeds with the participation of hydroxyl radicals. 

The chemical properties of the block copolymers are similar to those of unvulcanized styrene-butadiene rubber. Thus the block copolymers are soluble in a range of solvents, including chlorinated and aromatic hydrocarbons, esters and ketones. 

V, Cr, and Mn ions were the most active. V-MCM-41 catalyst, with a better structural pattern, showed a better conversion in the oxidation of ethyl benzene and diphenyl methane than Ti- and Cr-MCM-41 catalysts [80]. The catalytic activity of MCM-41 modified with V, Co, Nb, and La was evidenced in the oxidation with H2O2 of alcohok (hexanol, cyclohexanol, and hexanediol) and aromatic hydrocarbons (styrene, benzene, and toluene). The effect of synthesis method on catalytic properties was evidenced for all of them [35,79]. 

Polystyrene is resistant to hot and cold water, weak acids and bases, aqueous solutions of inorganic salts, amines, alcohols, fats, and oils. Polystyrene is not resistant to oxidizing acids, halogens, aliphatic and chlorinated (saturated and unsaturated) hydrocarbons, esters, ketones, ethers, aldehydes, and aromatic hydrocarbons [86]. Table A. 14 Appendix compiles the chemical resistance of polystyrene and styrene copolymers. 

Determination of Styrene Monomer and Aromatic Hydrocarbons in Aqueous and Fatty (Liquid Paraffin) Extractants... 

The range of solvents that can be used for the living anionic polymerization of styrene is limited due to the highly reactive anionic initiators and the propagating chain-end carbanions. The solvents of choice are mainly aliphatic and aromatic hydrocarbons and ethers. Typically, the following two polymerization conditions are used in the living anionic polymerization of styrene. In the first condition, the polymerization is carried out in nonpolar hydrocarbon media such as cyclohexane, benzene, toluene, and similar hydrocarbons at... 

An interesting reaction related to the selective dimerization of styrene may be the oxo-acid catalyzed addition of styrene to aromatic hydrocarbons to yield 1,1 -diphenyl-ethane derivatives (37) (Eq. (26)). This process differs from the cationic dimerization of styrene in that the unsaturated bond to be attacked by the styryl cation is aromatic, not vinylic as in the latter. Mechanistically, however, these reactions are quite similar, particularly in that both require rapid and efficient deprotonation of the carbo-cationic intermediate formed by the addition of the styryl cation. The high proton-... 

Saturated and unsaturated, aliphatic and aromatic hydrocarbons are produced with benzene and toluene in high yield In helium quantitative yield of HCl, remainder residue and hydrocarbons benzene is major volatile hydrocarbons product Aliphatic hydrocarbons, benzene (major product), toluene, ethylbenzene, o-xylene, monochlorobenzene, styrene, vinyl toluene, p-dichlorobenzene, o-dichlorobenzene, indene, 1,3,5-trichlorobenzene, 1,2,4-trichlorobenzene, naphthalene, a-methylnaphthalene, P-methylnaphthalene effect of ZnO, Sn02, and AI2O3 on the yields of products is also recorded HCl, CO 2, ethene, ethane, propane, 1-butene, 2-butene, 1-pentene, 267... 

Compatible with most polyolefins, styrenics, polycarbonate, thermoplastic polyesters and elastomers. Very soluble in chlorinated and aromatic hydrocarbons. Moderate solubility in ketones and esters. Low solubility in aliphatic hydrocarbons and alcohols. Insoluble in water. 

---