Xylylene_dibromide

Xylylene dibromide

Xylylene dibromide

Chemical compound

Xylylene dibromide is an organic compound with the formula C6H4(CH2Br)2. It is an off-white solid that, like other benzyl halides, a strong lachrymator. It is a useful reagent owing to the convenient reactivity of the two C-Br bonds.[1] Two other isomers are known, para- and meta-xylylene dibromide.

Quick Facts Identifiers, Properties ...

Synthesis

It is prepared by the photochemical reaction of ortho-xylene with bromine:[2]

C6H4(CH3)2 + 2 Br2 → C6H4(CH2Br)2 + 2 HBr

Reactions

Further bromination gives the tetrabromide:[3]

C6H4(CH2Br)2 + 2 Br2 → C6H4(CHBr2)2 + 2 HBr

Upon reaction with thiourea followed by hydrolysis of the intermediate bisisothiouronium salts, xylylene dibromide can be converted to the dithiol C6H4(CH2SH)2.[4]

Xylylene dibromide is a precursor to the ephemeral molecule ortho-quinonedimethane, also known as xylylene. This species can be trapped when the dehalogenation is conducted in the presence of iron carbonyl.[5]

Coupling of xylylene dibromide by treatment with lithium metal gives dibenzocyclooctane, precursor to dibenzocyclooctadiene.[6]

References

  1. [1]
    Bornstein, J.; Shields, J. E. (1967). "2-(p-Tolylsulfonyl)dihydroisoindole". Organic Syntheses. 47: 110. doi:10.15227/orgsyn.047.0110.
  2. [2]
    Emily F. M. Stephenson (1954). "o-Xylylene Dibromide". Organic Syntheses. 34: 100. doi:10.15227/orgsyn.034.0100.
  3. [3]
    Bill, J. C.; Tarbell, D. S. (1954). "o-Phthalaldehyde". Organic Syntheses. 34: 82. doi:10.15227/orgsyn.034.0082.
  4. [4]
    Mayerle, J. J.; Denmark, S. E.; Depamphilis, B. V.; Ibers, James A.; Holm, R. H. (1975). "Synthetic Analogs of the Active Sites of Iron-Sulfur Proteins. XI. Synthesis and Properties of Complexes Containing the Iron Sulfide (Fe2S2) Core and the Structures of Bis[o-Xylyl-α,α'-Dithiolato-μ-Sulfido-Ferrate(III)] and bis[p-Tolylthiolato-μ-Sulfido-Ferrate(III)] Dianions". Journal of the American Chemical Society. 97 (5): 1032–1045. doi:10.1021/ja00838a015.
  5. [5]
    Kerber, Robert C.; Ribakove, Everett C. (1991). "Formation of Iron Carbonyl Complexes of Reactive Polyenes from Dihalides involving the Free Polyene". Organometallics. 10 (8): 2848–2853. doi:10.1021/om00054a059.
  6. [6]
    Géraldine Franck, Marcel Brill, Günter Helmchen (2012). "Dibenzo[a,e]cyclooctene: Multi-gram Synthesis of a Bidentate Ligand". Organic Syntheses. 89: 55. doi:10.15227/orgsyn.089.0055.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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