Ethylbenzene


 * Ethylbenzene ** is an organic compound with the formula C 6 H 5 CH 2 CH 3 . This aromatic hydrocarbon is important in the petrochemical industry as an intermediate in the production of styrene, which in turn is used for making polystyrene, a common plastic material.

Ethylbenzene is a colorless organic liquid with a sweet, gasoline-like odor. The greatest use for ethylbenzene, more than 99% of the times, is to made styrene. Styrene is another organic liquid used as a building block for many plastics. It is also used as a solvent for coatings, and in the making of rubber and plastic wrap.

The MCLG for ethylbenzene is 0.7 mg/L or 700 ppb. EPA has set this level of protection based on the best available science to prevent potential health problems. EPA has set an enforceable regulation for ethylbenzene, called a maximum contaminant level (MCL), at 0.7 mg/L or 700 ppb. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. In this case, the MCL equals the MCLG, because analytical methods or treatment technology do not pose any limitation. When routine monitoring indicates that ethylbenzene levels are above the MCL, your water supplier must take steps to reduce the amount of ethylbenzene so that it is below that level. Water suppliers must notify their customers as soon as practical, but no later than 30 days after the system learns of the violation. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health. Although often present in small amounts in crude oil, ethylbenzene is produced in bulk quantities by combining benzene and ethylene in an acid-catalyzed chemical reaction:

C6H6 + C2H4 → C6H5CH2CH3 Approximately 24,700,000 tons were produced in 1999. Catalytic dehydrogenation of the ethylbenzene then gives hydrogen and styrene:

C6H5CH2CH3 → C6H5CH=CH2 + H2 Ethylbenzene has been used as a solvent for aluminum bromide in the anhydrous electrodeposition of aluminium. Ethylbenzene is also an ingredient in some paints, and solvent grade xylene (xylol) is nearly always contaminated with a few percent of ethylbenzene.