Cumene (isopropylbenzene) is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

that contains a

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

ring with an isopropyl

substituent A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as '' side ...

. It is a constituent of

crude oil Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...

and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 °C. Nearly all the cumene that is produced as a pure compound on an industrial scale is converted to

cumene hydroperoxide Cumene hydroperoxide is the organic compound with the formula C6H5CMe2OOH (Me = CH3). An oily liquid, it is classified as an organic hydroperoxide. Products of decomposition of cumene hydroperoxide are methylstyrene, acetophenone, and cumyl al ...

, which is an intermediate in the synthesis of other industrially important chemicals, primarily

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...

and

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscibl ...

(known as the

cumene process The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It w ...

Production

Commercial production of cumene is by Friedel–Crafts alkylation of

with

propylene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petro ...

. Cumene producers account for approximately 20% of the global demand for benzene. The original route for manufacturing of cumene was by alkylation of benzene in the liquid phase using sulfuric acid as a catalyst, but because of the complicated neutralization and recycling steps required, together with corrosion problems, this process has been largely replaced. As an alternative, solid

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...

(SPA) supported on alumina was used as the

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

Industrial synthesis of cumene (gas-phase)

Since the mid-1990s, commercial production has switched to

zeolite Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These p ...

-based catalysts. In this process, the efficiency of cumene production is generally 70-75%. The remaining components are primarily polyisopropyl benzenes. In 1976, an improved cumene process that uses

aluminum chloride Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contam ...

as a catalyst was developed. The overall conversion of cumene for this process can be as high as 90%. The addition of two equivalents of propylene gives

diisopropylbenzene In organic chemistry, the diisopropylbenzenes constitute a group of aromatic hydrocarbons, whose chemical structure consists of a benzene ring () with two isopropyl groups () as substituents. Through their different arrangement, they form three st ...

(DIPB). Using transalkylation, DIPB is comproportionated with benzene to give cumene.

Autoxidation

Depending on the conditions,

autoxidation Autoxidation (sometimes auto-oxidation) refers to oxidations brought about by reactions with oxygen at normal temperatures, without the intervention of flame or electric spark. The term is usually used to describe the gradual degradation of organic ...

of cumene gives

dicumyl peroxide Dicumyl peroxide is an organic compound with the formula (Me = CH3). Classified as a dialky peroxide, it is produced on a large scale industrially for use as an initiator for the production of low density polyethylene. Production It is synth ...

. Both reactions exploit the weakness of the tertiary C-H bond. The tendency of cumene to form peroxides by autoxidation poses safety concerns.CDC - NIOSH Pocket Guide to Chemical Hazards
/ref> Tests for peroxides are routinely conducted before heating or distilling.

References

External links

National Pollutant Inventory - Cumene fact sheetCumene Production from Benzene and Propylene Using Aluminum Chloride Catalyst
{{Hydrocarbons Hazardous air pollutants Alkylbenzenes C3-Benzenes Commodity chemicals Suspected carcinogens IARC Group 2B carcinogens Isopropyl compounds

Production

Autoxidation

See also

References

External links