Chemistry:Tetrabromo-o-xylene

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Tetrabromo-o-xylene
Tetrabromo-o-xylene.svg
Names
Preferred IUPAC name
1,2-Bis(dibromomethyl)benzene
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 236-176-2
UNII
Properties
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 pictograms GHS05: CorrosiveGHS07: HarmfulGHS09: Environmental hazard
GHS Signal word Danger
H314, H335, H400
P260, P261, P264, P271, P273, P280, P301+330+331, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P363, P391, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Tracking categories (test):

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]

C
6
H
4
(CH
3
)
2
+ 4 Br
2
→ C
6
H
4
(CHBr
2
)
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]

C
6
H
4
(CHBr
2
)
2
+ 2 NaI → C
6
H
4
(=CHBr)
2
+ 2 NaBr + I
2
C
6
H
4
(=CHBr)
2
→ C
6
H
4
(CHBr)
2

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

References

  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.