Alkylbenzene

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Toluene (or methylbenzene) is a common chemical found in chemistry laboratories.

An alkylbenzene is a chemical compound that contains a monocyclic aromatic ring attaching to one or more saturated hydrocarbon chains.[1] 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 CnH2n-6.[2]

Safety hazards of toluene. Oftentimes, toluene is used as an organic solvent.

Alkylbenzenes are a very important class of

synthetic sulfonates. However, LABs are more industrially favoured since the discovery of its extensive biodegradable yield over BAB-based sulfonates in the 1960s.[3]

Examples of alkylbenzenes

Parent compound:

Benzene

Alkylbenzenes
Benzene Toluene
Xylenes
o-xylene
m-xylene
p-xylene
Trimethylbenzenes
hemimellitene
pseudocumene
 mesitylene
Tetramethylbenzenes
prehnitene isodurene durene
Miscellaneous
Ethylbenzene Cumene p-Cymene
Xylene isomers are also used as solvents in laboratories. Note that in the photo, o-xylene, not being stored in a brown glass bottle, appears to have auto-oxidized.

Reactions

  • alkyl halides with aromatic compounds in the presence of a catalyst such as AlCl3, HF, or H2SO4.[4]

Spectroscopy

Alkylbenzene isomers can be differentiated by observing the position of alkyl

chemical ionization-proton exchange mass spectrometry. Conventional GC-MS yields limited results because the isomers have identical molecular weight and substituents.[6]

Production

Some alkylbenzenes such as toluene, trimethylbenzenes, and tetramethylbenzenes occur naturally in coal tar oil and as byproducts of the crude oil refinery process. Others can be prepared by Friedel-Crafts alkylation.[3]

Alkylbenzenes used to be synthesized from

tetrapropylene, however, the reaction is now rarely used because of the low biodegradable alkylbenzene sulfonates it yields.[3]

Safety hazards

Alkylbenzenes are flammable. Most of them are eye and skin irritants and pose an acute health hazard when ingested. Alkylbenzenes are toxic to aquatic life with long-lasting effects.

Application

Synthetic sulfonates

Alkylbenzenes are the primary raw material in making synthetic alkylbenzene sulfonates. Synthetic sulfonates are the most widely used

rust inhibitors, dispersants, surfactants for enhanced oil recovery, ore-floatation agents, and wetting agents, among others. LABs such as alkylbenzene, dialkylbenzene, and alkyltoluene are most commonly used to prepare sulfonate detergents.[4]

Solvent use

Some less substituted alkylbenzenes such as toluene and xylene are commonly used as solvents industrially.

Literature

References

  1. PMID 18904921
    .
  2. OCLC 1333919856
    .
  3. ^
    S2CID 242394133
    , retrieved 2023-04-12
  4. ^
    OCLC 1003859957.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link
    )
  5. S2CID 242435919
    .
  6. ISSN 0003-2700
    .
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