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In commercial applications, the alkylating agents are generally alkenes, some of the largest scale reactions practiced in industry.Such alkylations are of major industrial importance, e.g. for the production of ethylbenzene, the precursor to polystyrene, from benzene and ethylene and for the production of cumene from benzene and propene in cumene process:
Benzene is sufficiently nucleophilic that it undergoes substitution by acylium ions and alkyl carbocations to give substituted derivatives. Electrophilic aromatic substitution of benzene. The most widely practiced example of this reaction is the ethylation of benzene. Approximately 24,700,000 tons were produced in 1999. [73]
Chemical synthesis plays a crucial role across various industries, enabling the development of materials, medicines, and technologies with significant real-world impacts. Catalysis : The development of catalysts is vital for numerous industrial processes, including petroleum refining, petrochemical production, and pollution control.
First performed by Justus von Liebig in 1838, [1] it is the first reported example of a rearrangement reaction. [2] It has become a classic reaction in organic synthesis and has been reviewed many times before. [3] [4] [5] It can be viewed as an intramolecular redox reaction, as one carbon center is oxidized while the other is reduced. Scheme 1.
The term stems from cumene (isopropyl benzene), the intermediate material during the process. It was invented by R. Ūdris and P. Sergeyev in 1942 (USSR), [1] and independently by Heinrich Hock in 1944. [2] [3] This process converts two relatively cheap starting materials, benzene and propylene, into two more valuable ones, phenol and acetone.
Steam distillation apparatus. Steam distillation is used in many of the recipes given in the Kitāb al-Taraffuq fī al-ʿiṭr ('Book of Gentleness on Perfume'), also known as the Kitāb Kīmiyāʾ al-ʿiṭr wa-l-taṣʿīdāt ('Book of the Chemistry of Perfume and Distillations'), attributed to the early Arabic philosopher al-Kindi (c. 801 –873). [5]
Alkylbenzenes are derivatives of benzene, in which one or more hydrogen atoms are replaced by alkyl groups. The simplest member, toluene (or methylbenzene), has the hydrogen atom of the benzene ring replaced by a methyl group. The chemical formula of alkylbenzenes is C n H 2n-6. [2] Safety hazards of toluene.
In organic chemistry, some dehydration reactions are subject to unfavorable but fast equilibria. One example is the formation of dioxolanes from aldehydes: [9] RCHO + (CH 2 OH) 2 RCH(OCH 2) 2 + H 2 O. Such unfavorable reactions proceed when water is removed by azeotropic distillation.