Haloalkanes and Haloarenes

• No.of Halogens

  Monohalo, dihalo, trihalo
• Hybridisation of C in C-X (monohalo composition)

  C-X (C= sp³)

  • Haloalkanes C(sp3)-C(sp3)-X
  • Allylic C=C(sp2)-C(sp3)-X
  • Benzylic - same as allylic but in benzene
• Common names

  • n alkyl (C-C-C-C-C)
  • 2° alkyl (C-CX-C-C)
  • 3° alkyl
  • iso alkyl
  • neo alkyl (4°)
• C=C(sp2)-X

  • Vinylic -C=C(sp2)-X
  • Haloarenes (same as vinylic but with benzene)
• Physical properties of alkyl halides

  Depend upon

  • nature of intermolecular source of attraction
  • mass
• Boiling point

  The one with the least branching will have a higher boiling point as when branching increases, the SFA decreases meaning the area of contact also decreases, this results in reducing of vanderwaal forces and the boiling point of more branched structure will be low.
• RI, RCl, RBr, RF

  RI- heaviest

  RF- most electronegative

  RF<RCl<RBr<RI
• Why RI is considered

  Mass is considered because I has much more mass as compared to the rest
• Solubility

  • like dissolves like
  • bond broken - energy req.
  • bond formed- energy release
• Why are alkyl halides partially soluble/ insoluble in water?

  • H bonding > dp-dp
  • Energy req to break h bond wont be compensated by the energy released by the dp-dp bond of the new bond formed
• Preparation of alkyl halides

  By:

  • alkenes
  • alkynes
  • alkanes
  • alcohol
  • halogen replacement
• By alkenes

  • alkene + hcl = alkane
  • alkene + hbr in presence of organic peroxide= alkane
  • alkene + Br2 in +nce of CCl4= alkane

  same for alkyne, just double the steps
• Alcohol

  • ROH+ H2SO4+NaCl/Br= RCl+ H20+NaHSO4
  • ROH+H2SO4+NaI= not give RI
  • ROH+H3PO4+NaI= RI
  • ROH+HCl in +nce of ZnCl2= RCl + H2O (also used for differentiating b/w 1°,2° and 3°alcohol)