Alkyl Halides

145 Chem 1

145 Chem 2

Alkyl Halides

145 Chem 3

• CH3-X and R-CH2-X : Primary alkyl halide.

• (R)2-CH-X : Secondary alkyl halide.

• (R)3-C-X : Tertiary alkyl halide.

Classes and Names of Halogen Compounds

According to hydrocarbon gp.

1-Alkyl halides( R-X) has a halogen atom bonded to one sp3 hybrid C atom

2-Allylic halides has a halogen atom bonded to one sp3 hybrid C atom

3-Vinylic halides has a halogen atom bonded to one sp2 hybrid C atom

4-Benzylic halides has a halogen atom bonded to Carbone one away from aromatic ring

5-Aryl halides has a halogen atom bonded directly to an aromatic ring

Alkyl Halides

1-Alkyl halides ( R-X): CH3-Cl CH3-CH2-Br (CH3)2-CH-F

Common

Methyl Chloride Ethyl bromide Isopropyl fluoride

IUPAC Chloromethane Bromoethane 2-Fluoropropane

Class 1° 1° 2°

Common

Cyclohexyl Iodide t.Butyl bromide Methylcyclopentyl

chloride

IUPAC Iodocyclohexan

e2-Bromo-2-

methylpropane 1-Chloro-1-

methylcyclopentane

Class 2° 3° 3° 145 Chem 4

CH3

H3C

CH3

Br

CH3ClI

Alkyl Halides

145 Chem 5

3-Allyl halides

C=C-C- X

CH2=CHCH2ClAllyl chloride

3-Chloro-1-propene

Cl

3-Chlorocyclopentene

4-Benzylic halides: Ar-C-X

CH2Cl

Benzyl Chloride

Br

2-Vinylic halides

Bromocyclohexene

C=C-X

CH2=CHBr Vinyl bromideBromoethene

5-Aryl halides: Ar-X (X directly attached to )

ClBr

CLCH3

Chlorobenzene p-Bromo toluene

Notice

Alkyl Halides

145 Chem 6

PHYSICAL PROPERTIES OF ORGANIC HALIDES• All organic halides are insoluble in water and soluble in common

organic solvents.

• In an alkyl halide, the halogen is more electronegative that carbon

• The boiling points increases with increasing in molecular weights.

• Alkyl halides have higher melting point than the corresponding

alkanes, alkenes, and alkynes because:

1. Polarity

2. Molecular weight (In series of halides BP. F <Cl <Br <I)

Alkyl Halides

145 Chem 7

PREPARATION OF HALOGEN COMPOUNDS1- Direct halogenation of hydrocarbons

a- Halogenation of alkanes

b- Halogenation of alkenes

R H X2+UV or heat

R X HX+ (X= Cl, Br)

CH4 Cl2UV or Heat CH3Cl + HCl

CH2 CH CH2R + X2

UV or heatCH2 CH CHR

X

+ HX

CH2 CH CH2R X2 CH CH2RCH2

X X

CCl4+

CH2 CH CH2R CH CH2RCH3

X

CCl4HX+

Alkyl Halides

CH-CH3H2C Br2 BrCH2-CH=CH2 HBr UV

CH3CH=CHCH3 + H-Cl CH3CHHCHClCH3 (one)

CH3CH=CH2 + Cl2 CH3CHClCH2Cl CCl4

CCl4

145 Chem 8

c- Halogenation of alkynes

CH C CH2R + X2

UV or heatCH C CHR

X

+ HX

CH C CH2R X2 C CH2RCH

X X

X XCCl4+

CH C CH2R C CH2RCH3

X

XCCl4

HX+

Alkyl Halides

+ Br2

Br

Br

+ Br2

Br

Br

Br

Br

HCl

Cl

H

HCl

Cl

Cl

H

H

d- Halogenation of alkyl benzenes and aromatic ring

145 Chem 9

X2+

CH2R

UV or heat

CHXR

X2+

X

FeX3

+ HX

+ HX

Alkyl Halides

CH2CH3 CH2CH2Cl CHCl-CH3

HCl UVCl2

CH3 CH2Br

HBrBr2 UV

145 Chem 10

2- Conversion of alcoholsHCl/ZnCl2

OH Clor SOCl2or PCl3or PCl5

R R

H3COH

PCl3 H3CCl + H2O

OH SOCl2Cl

+ SO2 + HCl

HCl/ZnCl2OH Cl

PCl3+ P(OH)3

CH3

OH

CH3

Cl

CH3-OH + HBr CH3-BrHeat H2O

C

C2H5

C2H5

C2H5 OHHCl

CC2H5

C2H5

C2H5 Cl H2OZnCl2

Alkyl Halides

Reactions of Organic Halides1- Nucleophilic Subtitution Reactions

Nu- = -OH, -OR, -OCOR, -SH, -SR, -CN,

145 Chem 11

X NuR R+ Nu- + X-

Br

dil KOH

OH primary and secondary

Cl NaCN CN

PhO-Na+Cl OPh

R-C C

Alkyl Halides

145 Chem 12

Alkyl Halides

HC C-Na+Br

Br

HC CNa

CH

Cl

O

NaNH2 NH2

O

Br I

NaIAcetone

2- Elimination Reactions

145 Chem 13

Alkyl Halides

C C

XX

Strong base

- 2 HXC C

Br

Br

1,2-dihaloalkane

Excess NaNH2

- 2HBr

Br

Br

Br

KOH/ alcohol

heat

NaNH2

heat

3- Reaction of Grignared reagent

a- Formation of Grignard reagent

b- Reaction of Grignard reagent

145 Chem 14

dry etherR X + Mg R MgX (X= Cl, Br, I)

dry etherAr X + Mg Ar MgX (X= Cl, Br, I)

R MgX

OH2R H + Mg(OH)X

R'OHR H + Mg(OR')X

CH CHR H + Mg(HCC)X

Alkyl Halides

CH3CH2Br + Mg2+ Dry ether CH3CH2MgBr

Grignard reagent

CH3CH2MgBrH3O

+

CH3CH3 + Mg(OH)Br

15

Thank You for your kind attention !

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Alkyl Halides