Tetrabromo-o-xylene

Tetrabromo-o-xylene
Names
	Preferred IUPAC name 1,2-Bis(dibromomethyl)benzene
Identifiers
CAS Number	13209-15-9;
3D model (JSmol)	Interactive image;
ChemSpider	75099;
ECHA InfoCard	100.032.873
EC Number	236-176-2;
PubChem CID	83234;
UNII	3WG2H68VX4;
CompTox Dashboard (EPA)	DTXSID7022255 ;
	InChI InChI=1S/C8H6Br4/c9-7(10)5-3-1-2-4-6(5)8(11)12/h1-4,7-8H Key: LNAOKZKISWEZNY-UHFFFAOYSA-N;
	SMILES C1=CC=C(C(=C1)C(Br)Br)C(Br)Br;
Properties
Chemical formula	C8H6Br4
Molar mass	421.752 g·mol−1
Appearance	off white solid
Melting point	115–116 °C (239–241 °F; 388–389 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314, H335, H400
Precautionary statements	P260, P261, P264, P271, P273, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P363, P391, P403+P233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

α,α,α',α'-Tetrabromo-o-xylene is an organobromine compound with the formula C₆H₄(CHBr₂)₂. Three isomers of α,α,α',α'-Tetrabromoxylene exist, but the ortho derivative is most widely studied. It is an off-white solid. The compound is prepared by the photochemical reaction of o-xylene with elemental bromine:^[1]

C₆H₄(CH₃)₂ + 4 Br₂ → C₆H₄(CHBr₂)₂ + 4 HBr

Reaction of α,α,α',α'-tetrabromo-o-xylene with sodium iodide affords α,α'-dibromo-o-xylylene, which can be trapped with dienophiles to give naphthylene. In the absence of trapping agents, the xylylene relaxes to α,α'-dibromobenzocyclobutane:^[2]

C₆H₄(CHBr₂)₂ + 2 NaI → C₆H₄(=CHBr)₂ + 2 NaBr + I₂

C₆H₄(=CHBr)₂ → C₆H₄(CHBr)₂

Cycloadditions of these xylylenes provides a pathway to acenes.^[3]

References

^ Bill, J. C.; Tarbell, D. S. (1954). "o-Phthalaldehyde". Organic Syntheses. 34: 82. doi:10.15227/orgsyn.034.0082.
^ Cava, M. P.; Deana, A. A.; Muth, K. (1959). "Condensed Cyclobutane Aromatic Compounds. VIII. The Mechanism of Formation of 1,2-Dibromobenzocyclobutene; A New Diels-Alder Synthesis". Journal of the American Chemical Society. 81 (24): 6458–6460. doi:10.1021/ja01533a032.
^ Paddon-Row, Michael N.; Patney, Harish K. (1986). "An Efficient Synthetic Strategy for Naphthalene Annellation of Norbornenylogous Systems". Synthesis. 1986 (4): 328–330. doi:10.1055/s-1986-31603. S2CID 94212857.

[OS-1] Bill, J. C.; Tarbell, D. S. (1954). "o-Phthalaldehyde". Organic Syntheses. 34: 82. doi:10.15227/orgsyn.034.0082.

[2] Cava, M. P.; Deana, A. A.; Muth, K. (1959). "Condensed Cyclobutane Aromatic Compounds. VIII. The Mechanism of Formation of 1,2-Dibromobenzocyclobutene; A New Diels-Alder Synthesis". Journal of the American Chemical Society. 81 (24): 6458–6460. doi:10.1021/ja01533a032.

[3] Paddon-Row, Michael N.; Patney, Harish K. (1986). "An Efficient Synthetic Strategy for Naphthalene Annellation of Norbornenylogous Systems". Synthesis. 1986 (4): 328–330. doi:10.1055/s-1986-31603. S2CID 94212857.

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