Benzene, alkylation toxicity

In order to achieve high yields, the reaction usually is conducted by application of high pressure. For laboratory use, the need for high-pressure equipment, together with the toxicity of carbon monoxide, makes that reaction less practicable. The scope of that reaction is limited to benzene, alkyl substituted and certain other electron-rich aromatic compounds. With mono-substituted benzenes, thepara-for-mylated product is formed preferentially. Super-acidic catalysts have been developed, for example generated from trifluoromethanesulfonic acid, hydrogen fluoride and boron trifluoride the application of elevated pressure is then not necessary. 

Benzene is a flammable liquid and its vapors are toxic and explosive. Low concentrations are dangerous on continued inhalation because benzene affects the blood forming function of the bone marrow and it is a cancirogen. Dermatitis may result from repeated skin contact. Alkyl derivatives such as toluene and xylenes are far less toxic and are, therefore, much safer than benzene for use in solvents. Some of the symptoms of benzene poisoning are dizziness, constriction of the chest, and tightening of the leg muscles. 

Friedel-Crafts alkylations are among the most important reactions in organic synthesis. Solid acid catalysts have advantages in ease of product recovery, reduced waste streams, and reduction in corrosion and toxicity. In the past, people have used (pillared) clays (18), heteropolyacids (19) and zeohtes (20) for Friedel-Craft alkylations, with mixed success. Problems included poor catalyst stabihty and low activity. Benzylation of benzene using benzyl chloride is interesting for the preparation of substitutes of polychlorobenzene in the apphcation of dielectrics. The performance of Si-TUD-1 with different heteroatoms (Fe, Ga, Sn and Ti) was evaluated, and different levels of Fe inside Si-TUD-1 (denoted Fei, Fe2, Fes and Feio) were evaluated (21). The synthesis procedure of these materials was described in detail elsewhere (22). 

The toxicities of nine alkyl aromatics (4) are appreciably less than those of the polycyclic aromatics. No signihcant retardation is observed in benzene-deuterium oxide exchange reactions at 30° even when the poisons are present in benzene in concentrations of 3.6 mole %. The high temperature exchange rate (Table II) of sterieally unhindered ring positions in the alkylbenzenes indicates that adsorption strength... 

The normal-propylamine NPT has been made by the oxalylamide route, with the amide with a mp 179-181 °C (75%) from benzene and NPT hydrochloride mp 186-187 °C (33%) from MeOH/benzene. An attempt to make NPT by the alkyl halide procedure failed. Using these same ratios of reactants, there was the formation of a sizable quantity of DPT with appreciable unreacted tryptamine presence (T NPT DPT/1 5 4). A recycling under the same conditions gave T NPT DPT/0 3 7) and a third cycle gave only DPT, but with a loss of almost 90% of the material presumably to quaternary salt formation. Interestingly NPT is less toxic than DPT in experimental mice, but has not been assayed yet in man. 

You are interested in the well-being of Ampelisca abdita, living in a harbor whose sediments are contaminated with 4-nonylphenol. You remember that the lethal volume fraction of narcotic chemicals in membranes is about 0.01 L compound L I lipid. If the sediment contains 2% organic carbon by weight, and the amphipod is assumed to accumulate body burdens up to equilibrium with the sediments on which it lives, what sediment concentration of 4-nonylphenol should be deemed acceptable with respect to baseline toxicity Assume a log ,lipsw = 5.5 for 4-nonylphenol. Use Eq. 9-26c (alkylated and chlorinated benzenes ) for estimating Kioc. Compare your result with the findings of Fay et al. (2000), who observed a die-off of half the amphipods when they were exposed to about 0.16 g 4-nonylphenol - kg-1 sediment. 

Roberts, D.W. 1989. Aquatic toxicity of linear alkyl benzene sulfonates (LAS)—A QSAR analysis. Communicaciones presentadas a las Jornadas Espanol de la Detergencia 29, 35-43. 

Dimethylsulfide is an alkyl sulfide or thioether. It is a volatile liquid (bp, 38°C) that is moderately toxic by ingestion. Thiophene is the most common cyclic sulfide. It is a heat-stable liquid (bp, 84°C) with a solvent action much like that of benzene. It is used in the manufacture of pharmaceuticals and dyes, as well as resins that also contain phenol or formaldehyde. Its saturated analog is tetrahydrothiophene, or thiophane. 

Treatment of carboxylic acids with Pb(OAc)4 can also be used for the alkylation of heteroaromatics, but it is toxic. Eq. 5.8 shows the introduction of a phenyl group to the cubane by the treatment of 1,4-cubanedicarboxylic acid monoester (13) with Pb(OAc)4 in benzene [20]. 

Roberts, D.W. 1989. Aquatic toxicity of linear alkyl benzene sulphonates (LAS) - a QSAR analysis. Communicaciones Presentadas a las Jomadas del Comite Espanol de la Detergencia, 20 (1989) 35-43. Also in J.E. Turner, M.W. England, T.W. Schultz and N.J. Kwaak (eds.) QSAR 88. Proc. Third International Workshop on Qualitative Structure-Activity Relationships in Environmental Toxicology, 22-26 May 1988, Knoxville, Tennessee, pp. 91-98. Available from the National Technical Information Service, US Dept, of Commerce, Springfield, VA... 

Scope of the Problem. Petroleum hydrocarbons are the principal components in a wide variety of commercial products (e.g., gasoline, fuel oils, lubricating oils, solvents, mineral spirits, mineral oils, and crude oil). Because of widespread use, disposal, and spills, environmental contamination is relatively common. It is important to understand that petroleum products are complex mixtures, typically containing hundreds of compounds. These include various amounts of aliphatic compounds (straight-chain, branched-chain, and cyclic alkanes and alkenes) and aromatic compounds (benzene and alkyl benzenes, naphthalenes, and PAHs). In addition, many petroleum products contain nonhydrocarbon additives such as alcohols, ethers, metals, and other chemicals that may affect the toxicity of the mixture. 

As solvent, either kerosene or mixtures of alkyl benzenes like toluene or xylene have been proposed. Due to the toxicity of the latter, kerosene is widely preferred. 

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