Ethylbenzene is an organic compound with the formula . It is a highly flammable, colorless liquid with an odor similar to that of gasoline. This monocyclic aromatic hydrocarbon is important in the petrochemical industry as an reaction intermediate in the production of styrene, the precursor to polystyrene, a common plastic material. In 2012, more than 99% of ethylbenzene produced was consumed in the production of styrene. Occurrence and applications Ethylbenzene occurs naturally in coal tar and petroleum. The dominant application of ethylbenzene is its role as an intermediate in the production of polystyrene. Catalytic dehydrogenation of ethylbenzene gives hydrogen and styrene: → C6H5CH=CH2 + As of May 2012, more than 99% of all the ethylbenzene produced is used for this purpose. Ethylbenzene hydroperoxide, a reagent and radical initiator, is produced by autoxidation of ethylbenzene: C6H5CH2CH3 + O2 → C6H5CH(O2H)CH3 Niche uses Ethylbenzene is added to gasoline as an anti-knock agent to reduce engine knocking and increase the octane rating. Ethylbenzene is often found in other products, including pesticides, cellulose acetate, synthetic rubber, paints, and inks. Used in the recovery of natural gas, ethylbenzene may be injected into the ground. Production Ethylbenzene is produced on a large scale by combining benzene and ethene in an acid-catalyzed chemical reaction: + → In 2012, more than 99% of ethylbenzene was produced in this way. Thus, makers of ethylbenzene are the major buyers of benzene, claiming more than half of total output. Small amounts of ethylbenzene are recovered from the mix of xylenes by superfractioning, an extension of the distillation process. In the 1980s a zeolite-based process using vapor phase alkylation offered a higher purity and yield. Then a liquid phase process was introduced using zeolite catalysts. This offers low benzene-to-ethylene ratios, reducing the size of the required equipment and lowering byproduct production. Industrial accidents On January 5, 2011 a major fire took place at the Chemie-Pack storage facility in the Dutch Moerdijk industrial area. The fire started in a chemical reactor operated by Shell which overheated due to an exothermal runaway reaction between the metal oxide catalyst and ethylbenzene. Firefighting activities lead to massive environmental pollution. Total damage is estimated at 70 million Euro. Health effects The acute toxicity of ethylbenzene is low, with an LD50 of about 4 grams per kilogram of body weight. The longer term toxicity and carcinogenicity is ambiguous. Eye and throat sensitivity can occur when high level exposure