alkyl halides

14
Alkyl Halides King Saud University Chemistry Department 145 Chem 1

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King Saud University Chemistry Department. Alkyl Halides. King Saud University Chemistry Department. Classes and Names of Halogen Compounds. CH 3 -X and R-CH 2 -X : Primary alkyl halide. (R) 2 -CH-X : Secondary alkyl halide. (R) 3 -C-X : Tertiary alkyl halide. - PowerPoint PPT Presentation

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Page 1: Alkyl Halides

Alkyl Halides

King Saud University Chemistry Department

145 Chem 1

Page 2: Alkyl Halides

145 Chem 2

King Saud University Chemistry Department

• 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): 2-Allylic halides 3-Vinylic halides 4-Benzylic halides 5-Aryl halides

Page 3: Alkyl Halides

King Saud University Chemistry Department

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 Iodocyclohexane

2-Bromo-2-methylpropane

1-Chloro-1-methylcyclopentane

Class 2° 3° 3° 145 Chem 3

CH3

H3C

CH3

Br

CH3ClI

Page 4: Alkyl Halides

145 Chem 4

3-Allyl halides C=C-C- XCH2=CHCH2ClAllyl chloride

3-Chloro-1-propene

Cl

3-Chlorocyclopentene

4-Benzylic halides:Ar-C-X ( halogen one carbon away from aromatic ring)

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

CLCH3Chlorobenzene p-Bromo toluene

Page 5: Alkyl Halides

145 Chem 5

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

organic solvents.

• 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)

King Saud University Chemistry Department

Page 6: Alkyl Halides

145 Chem 6

PREPARATION OF HALOGEN COMPOUNDS1- Direct halogenation of hydrocarbonsa- Halogenation of alkanes

b- Halogenation of alkenes

King Saud University Chemistry Department

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+

Page 7: Alkyl Halides

145 Chem 7

King Saud University Chemistry Department

CH-CH3H2C Br2 BrCH2-CH=CH2 HBr UV

CH3CH=CHCH3 + H-Cl CH3CHHCHClCH3 (one)

CH3CH=CH2 + Cl2 CH3CHClCH2Cl CCl4

CCl4

c- Halogenation of alkynesCH 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+

Page 8: Alkyl Halides

d- Halogenation of alkyl benzenes and aromatic ring

145 Chem 8

King Saud University Chemistry Department

X2+

CH2RUV or heat

CHXR

X2+

XFeX3

+ HX

+ HX

+ Br2

BrBr

+ Br2

Br

Br

Br

Br

HCl

ClH

HCl

Cl

Cl

H

H

Page 9: Alkyl Halides

145 Chem 9

King Saud University Chemistry Department

CH2CH3 CH2CH2Cl CHCl-CH3

HCl UVCl2

CH3 CH2Br

HBrBr2 UV

Page 10: Alkyl Halides

145 Chem 10

2- Conversion of alcohols

King Saud University Chemistry Department

HCl/ZnCl2OH Cl

or SOCl2or PCl3or PCl5

R R

H3COH

PCl3 H3CCl + H2O

OH SOCl2 Cl+ SO2 + HCl

HCl/ZnCl2OH Cl

PCl3+ P(OH)3

CH3

OH

CH3

Cl

CH3-OH + HBr CH3-BrHeat H2O

C

C2H5

C2H5

C2H5 OHHCl

C C2H5

C2H5

C2H5 Cl H2OZnCl2

Page 11: Alkyl Halides

Reactions of Organic Halides1- Nucleophilic Subtitution Reactions

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

145 Chem 11

King Saud University Chemistry Department

X NuR R+ Nu- + X-

Br

dil KOH

OH primary and secondary

Cl NaCN CN

PhO-Na+Cl OPh

R-C C

HC C-Na+Br

Br

HC CNa

CH

Page 12: Alkyl Halides

2- Elimination Reactions

145 Chem 12

King Saud University Chemistry Department

Cl

O

NaNH2 NH2

O

Br I

NaIAcetone

CH3CH3

Br

conc KOH or C2H5O-Na

+ or PhO

-Na

+

EtOH / heat

CH3 CH3

CH3

CH3

CH3

ClC2H5O

-Na

+

EtOH / heatCH2

CH3

CH3

Page 13: Alkyl Halides

3- Reaction of Grignared reagenta- Formation of Grignard reagent

b- Reaction of Grignard reagent

145 Chem 13

King Saud University Chemistry Department

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

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

R MgX

OH2 R H + Mg(OH)X

R'OH R H + Mg(OR')X

CH CHR H + Mg(HCC)X

Page 14: Alkyl Halides

145 Chem 14

King Saud University Chemistry Department

CH3CH2Br + Mg2+ Dry ether CH3CH2MgBr

Grignard reagent

CH3CH2MgBrH3O

+

CH3CH3 + Mg(OH)Br