Benzocyclobutene

Benzocyclobutene

Names
IUPAC name Benzocyclobutene
Other names BCB
Identifiers
CAS Number	694-87-1 Y
ChEBI	CHEBI:87328 N
ChemSpider	62868 N
Jmol interactive 3D	Image
PubChem	24850072
InChI 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
SMILES C12=CC=CC=C1CC2
Properties
Chemical formula	C8H8
Molar mass	104.15 g·mol−1
Density	0.957 g/cm3
Boiling point	150 °C (302 °F; 423 K)
Refractive index (nD)	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 YN ?)
Infobox references

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

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-K dielectrics, or even intracortical neural implants.

Pharmaceuticals

The Benzocyclobutene moiety has also appeared in a number of drug molecules. As an example, the amphetamine derived compound appears in the following patent: Substituted 7-aminoalkylbicyclo-[4. 2. 0] octa-1, 3, 5-trienes.^[2]

Also see S33005 and the benzocyclobutene analog of 2-cb was prepared by Nichols et al.^[3]

Reactions

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 favoured.

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.^[4]

See also

• Benzocyclopropene
• Benzocyclobutadiene
• Xylylene

References