Dihalogen Derivatives
Dihalogen Derivatives
1. When both halogen atoms are attached to the same
carbon atom, they are said to be in the germinal (gem-) position.
Since the loss of two hydrogen atoms from the same carbon atom gives the alkylidene
group, gem-dihalides are named as the alkylidene same carbon atom gives
the alkylidene group, gem-dihalides are named as the alkylidene dihalides, e.g.,
CH3CHBr2 ethylidene dibromide; CH3CCl2CH3
isopropylidene dichloride.
2. When the two halogen atoms are on adjacent carbon
atoms they are said to be in the vicinal (vic-) position, and
these dihalides are named as the dihalide of the alkene from which they may be
prepared by the addition of halogen, e.g., CH2ClCH2Cl
ethylene dichloride; (CH3)CBrCH2Br isobutene dibromide.
3. When there is a halogen atom on each of the terminal
carbon atoms of the chain, i.e., in the α,ω-position, the
compound is named as the polymethylene dihalide, e.g., CH2ClCH2CH2CH2Cl
tetramethylene dichloride.
4. When the two halogen atoms occupy position other than
those mentioned above, the compounds are named as dihalogen derivatives
of the parent hydrocarbon, the positions of the halogen atoms being indicated
by numbers (us principle of lowest numbers), e.g.,
CH3CHClCH2CHClCH2CH3 2,4-dichlorohexane
The alkyl halides, gem-, vic- and α,ω-dihalides
may also be named by this (I.U.P.A.C.) system, e.g., CH3CH2CHBrCH3
2-bromobutane; CH2ClCH2CH2Cl 1,3-dichloropropane.
It was just short and sweet 🙂🙂🙂
ReplyDelete