Wikipedia

Benzocyclobutene

Benzocyclobutene (BCB) is a benzene ring fused to a cyclobutane ring. It has chemical formula C8H8.[1]

Benzocyclobutene
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
Bicyclo[4.2.0]octa-1,3,5-triene
Other names
Benzocyclobutane
BCB
Benzocyclobutene (not in accordance with IUPAC nomenclature)
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.161.355 Edit this at Wikidata
UNII
  • InChI=1S/C8H8/c1-2-4-8-6-5-7(8)3-1/h1-4H,5-6H2 ☒N
    Key: UMIVXZPTRXBADB-UHFFFAOYSA-N ☒N
  • InChI=1/C8H8/c1-2-4-8-6-5-7(8)3-1/h1-4H,5-6H2
    Key: UMIVXZPTRXBADB-UHFFFAOYAR
  • C12=CC=CC=C1CC2
Properties
C8H8
Molar mass 104.152 g·mol−1
Density 0.957 g/cm3
Boiling point 150 °C (302 °F; 423 K)
1.541
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

BCB is frequently used to create photosensitive polymers. BCB-based polymer dielectrics may be spun on or applied to various substrates for use in Micro Electro-Mechanical Systems (MEMS) and microelectronics processing. Applications include wafer bonding, optical interconnects, low-κ dielectrics, or even intracortical neural implants.

Reactions

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Benzocyclobutene is a strained system which, upon heating to approximately 180 °C, causes the cyclobutene to undergo a conrotatory ring-opening reaction, forming o-xylylene. Since this process destroys the aromaticity of the benzene ring, the reverse reaction is highly favored.

Thermal generation of o-xylylene from benzocyclobutene
Thermal generation of o-xylylene from benzocyclobutene

o-Xylylenes generated in this way have been used prolifically in cycloaddition reactions, which restore the aromaticity to the benzene ring, while forming a new annulated species.[2]

Derivatives

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Cyclized phenethylamine psychedelic drugs containing the benzocyclobutene ring system, including TCB-2, tomscaline, bromotomscaline, and 2CBCB-NBOMe (NBOMe-TCB-2), have been described.[3] A benzocyclobutene-derived amphetamine has been patented as well,[4] and a benzocyclobutene containing designer drug, the substituted cathinone derivative 3,4-EtPV, has been sold in Europe.[5] The benzocyclobutene derivative 2C-G-2 has also been claimed in a patent as an antiinflammatory,[6] but no synthesis or activity data is provided so it is unclear if it has actually been made.

The benzocyclobutene moiety also appears in the FDA approved medication ivabradine.

See also

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References

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  1. ↑ 164410 Benzocyclobutene 98%
  2. ↑ Mehta, G.; Kotha, S. (2001). "Recent chemistry of benzocyclobutenes" (PDF). Tetrahedron Lett. 57 (4): 625–659. doi:10.1016/s0040-4020(00)00958-3.
  3. ↑ Trachsel, D.; Lehmann, D.; Enzensperger, C. (2013). Phenethylamine: von der Struktur zur Funktion [Phenethylamines: From Structure to Function]. Nachtschatten-Science (in German) (1 ed.). Solothurn: Nachtschatten-Verlag. ISBN 978-3-03788-700-4. OCLC 858805226. Archived from the original on 12 August 2025. Retrieved 30 November 2025.{{cite book}}: CS1 maint: bot: original URL status unknown (link)
  4. ↑ US 3149159, "Substituted 7-aminoalkylbicyclo-[4. 2. 0]octa-1,3,5-trienes"
  5. ↑ "European Drug Report 2025 – Full Book" (PDF). European Union Drugs Agency (euda.europa.eu). 6 June 2025.
  6. ↑ Halpert M. Substituted phenethylamine for treating inflammation and psychological disorders. WO 2022/271982
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