classification and nomenclature of organic halides

ORGANIC HALIDESCHAPTER 6

Presented By: Cyra Mae R. Soreda

CLASSIFICATION AND NOMENCLATURE OF ALKYL HALIDESCOMMERCIALLY AND INDUSTRIALLY IMPORTANCE OF HALIDES

What Is an Alkyl Halide

An organic compound containing at least one carbon-halogen bond (C-X) X (F, Cl, Br, I) replaces H

Can contain many C-X bonds

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Hydrocarbons can also contain other atoms, such as halogens (F, Cl, Br, I). Halogen atoms are treated like branching alkyl groups.

Halogen Group Name

F fluoro

C chloro

Br bromo

I iodo

CLASSIFICATION OF ALKYL HALIDES

An alkyl halide is classified according to the kind of carbon that bears the halogen.

Alkyl halides are classified into three classes: Primary Alkyl Halide (Iº RX) Secondary Alkyl Halide (2º RX)

Tertiary Alkyl Halide (3º RX)

PRIMARY ALKYL HALIDE    

When one hydrogen atom of methyl group is replaced by an alkyl group, then the carbon of the substituted methyl is called Primary carbon atom.

CH3-CH2-I (Ethyl iodide) 

For example:

SECONDARY ALKYL HALIDE

When two hydrogen atoms of methyl group are replace by any alkyl group, then the carbon atom of substituted methyl is called secondary carbon atom..

For example:

TERTIARY ALKYL HALIDE

  When three hydrogen atoms of methyl groups are replaced by any alkyl group, then the carbon atom of the substituted methyl is called Tertiary carbon atom.

For example:

Classify These:

Classify These:

CH3 CH CH3

ClCH3CH2F

(CH3)3CBr

NOMENCLATURE OF ALKYL HALIDES

The two that are most widely used are: SYSTEMATIC NAME (IUPAC name)

ALTERNATIVE NAME (common names)

Both types can be applied to alcohols and alkyl halides.

Naming Alkyl Halides

Find and name the parent chain. As naming alkanes, select the longest chain as the parent chain.

Number the parent chain. Always number the chain beginning at the end nearer the first substituent, regardless of whether t is alkyl or halo.

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If more than one of the same kind of halogen is present, number each and use of the prefixes di-, tri-, tetra-, and so on. For example,

1,3-dichloro-3-methylbutane

If different halogens are present, number each according to its position. List all substituents in alphabetical order .

Naming if Two Halides or Alkyl Are Equally Distant from Ends of Chain

Begin at the end nearer the substituent whose name comes first in the alphabet

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Learning Check:

Give names for the following:

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Solution:

Give names for the following:

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Iodobutane1-chloro-3-

methylbutane1,5-dibromo-2,2-dimethylpentane

1,3-dichloro-3-methylbutane

1-chloro-3-ethyl-4-iodopentane 2-bromo-5-

chlorohexane

ALTERNATIVE NAMES or COMMON NAMES

Treat halogen as parent with alkyl side group

Name as alkyl halide. Useful only for small alkyl groups.

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Prefixes – the Halides

The family called alkyl halides does not have a suffix.

Halides are always named as prefixes.

Fluorine is called “fluoro” Chlorine is called “chloro” Bromine is called “bromo” Iodine is called “iodo”

COMMON Nomenclature of Alkyl Halides

Name the alkyl group and the halogen asseparate words (alkyl + halide)

CH3FCH3CH2CH2CH2CH

2Cl

CH3CH2CHCH2CH2CH3

Br

H

I

Learning Check:

Give names for the following:

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butyl iodide)

(isopentyl chloride)

CH3 CH CH2CH3

ClCH3 CH

CH3

CH2F

Chapter 6 22

“Trivial” Names

CH2X2 called methylene halide. CHX3 is a haloform. CX4 is carbon tetrahalide. Examples:

CH2Cl2 is methylene chloride CHCl3 is chloroform CCl4 is carbon tetrachloride.

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Dihalides

Geminal dihalide: two halogen atoms are bonded to the same carbon

Vicinal dihalide: two halogen atoms are bonded to adjacent carbons.

C

H

H

H

C

H

Br

Br

geminal dihalide

C

H

H

Br

C

H

H

Br

vicinal dihalide

Uses of Alkyl Halides

Solvents - degreasers and dry cleaning fluid Reagents for synthesis of other compounds Anesthetic: Halothane is CF3CHClBr

CHCl3 used originally (toxic and carcinogenic) Freons, chlorofluorocarbons or CFC’s

Freon 12, CF2Cl2, now replaced with Freon 22, CF2CHCl, not as harmful to ozone layer.

Pesticides - DDT banned in U.S.

Some uses:Fire-resistant solventsRefrigerantsPharmaceuticals and precursors

To God be the Glory!

Thank you for listening!