24.1 Classes of Organic compounds

24.2 Alphatic hydrocarbons

Alkane

cycloalkane

Alkenes

Alkynes

Aromatic hydrocarbon

Chemistry of functional groups

Alcohol , ethers , aldhyde and ketones ,carboxylic

acid , esters

Dr.Laila Al-Harbi

The chemistry of carbon compounds.

Carbon has the ability to form long chains and ring

structure.

Dr.Laila Al-Harbi

Alkanes have the general formula CnH2n+2 where n = 1,2,3,…

only single covalent bonds (C-C), sp3 hybridization

saturated hydrocarbons because they contain the maximum

number of hydrogen atoms that can bond with the number of

carbon atoms in the molecule.

Boiling point increase with increase molecular size because of

the increasing dispersion.

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

24-2

IUPAC International Union of Pure and Applied Chemistry.

each name consist of 3 parts

prefix

indicates position (1,3,…etc.) , number (di,tri, tetra …etc.) and type of branches (alkyl or substituent groups table 24-3)

parent

indicates the length of the longest carbon chain or ring

suffix

indicates the type of hydrocarbon

ane, ene, yne

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

24-2

Dr.Laila Al-Harbi

1 2 3 4 52-methylpentane

CH3 CH CH2 CH2 CH3

CH3

1 2 3 4 5

4-methylpentane

CH3 CH2 CH2 CH CH3

CH3

CH3 CH CH CH2 CH2 CH3

CH3

1 2 3 4 5 6

CH3

2,3-dimethylhexane

CH3 CH C CH2 CH2 CH3

CH3

1 2 3 4 5 6

CH3

3,3-dimethylhexane

Use prefixes di-, tri-, tetra-,

when there is more

than one alkyl branch

of the same kind.

Dr.Laila Al-Harbi

CH3 CH CH2 CH2CH CH3

CH3Br

2-bromo-5-methylhexane

CH3 CH CH CH3

Br

1 2 3 4

NO2

2-bromo-3-nitrobutane

CH2 CH2 CH CH3

Br

1 2 3 4

NO2

3-bromo-1-nitrobutane

The substituent group are

listed alphabetically

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

What is the IUPAC name of the following compound?

1 2 3 4 5 6 7 8CH3 CH CH2 CH CH2 CH2 CH3

C2H5

CH2

CH3

4-ethyl-2-methyloctane

What is the structure of 2-propyl-4-methylhexane?

1 2 3 4 5 6CH3 CH CH2 CH CH2 CH3

CH3C3H7

Dr.Laila Al-Harbi

Molecular formulae: A molecular formula simply counts the numbers of

each sort of atom present in the molecule, but tells you nothing about the

way they are joined together.

Example:

the molecular formula of butane is C4H10, and the molecular formula of

ethanol is C2H6O.

Structural formulae: A structural formula shows how the various atoms

are bonded.

Example:

ethanoic acid would be shown in a fully displayed form and asimplified

form as:

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

How many structural isomers does pentane, C5H12, have?

C C C C C

H H H H H

H

HHHHH

H

C C C C

H CH3 H H

H

HHHH

H

C C C

H CH3 H

H

HH

H

CH3

2,2-dimethylpropanen-pentane

2-methylbutane

Reactions of Alkanes

CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) ∆H0 = -890.4 kJ

1-Combustion ( exothermic)

2- Halogenations

CH4 (g) + Cl2 (g) CH3Cl (g) + HCl (g)light

2C2H6 (g) + 7O2 (g) → 4CO2 (g) + 6H2O (l) ∆H0 = -3119 kJ

If an excess of chlorine gas is present, the reaction can proceed further:

CH3Cl(g) + Cl2(g) → CH2Cl2(l) + HCl(g)

methylene chloride

CH2Cl2(l) + Cl2(g) → CHCl3(l) + HCl(g)

chloroform

CHCl3(l) + Cl2(g) → CCl4(l) + HCl(g)

carbon tetrachlorideDr.Laila Al-Harbi

Alkane not very reactive

Cycloalkanes

Alkanes whose carbon atoms are joined in rings are called cycloalkanes.

The general formula is Cn H2n where n = 3,4,… ( cycloalkane)

Dr.Laila Al-Harbi

AlkenesAlkenes have the general formula CnH2n where n = 2,3,… (sp2)

contain at least one carbon-carbon double bond ( also called olefins)

CH2CH CH2 CH3 CH3 CH CH CH3

cis-dichloroethylene trans-dichloroethylene

C C

Cl Cl

H H

C C

Cl H

H Cl

Geometric isomers of alkenes

2-butene1-butene

Cracking

C2H6 (g) CH2 = CH2 (g) + H2 (g)Pt

catalyst

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

Which of the following compounds has geometrical isomer ?

C C

H Cl

H HC C

H Cl

H Cl

C C

NO2 Cl

H HC C

NO2 Cl

H Cl

C C

Cl Cl

H H

NO ,Geometrical isomer NO ,Geometrical isomer

NO ,Geometrical isomer

yes ,it has geometrical isomer

yes ,it has geometrical isomer

Alkenes Reactions

Addition Reactions

CH2 = CH2 (g) + HBr (g) CH3- CH2Br (g)

CH2 = CH2 (g) + Br2 (g) → CH2B - CH2Br (g)

Symmetrical alkene

unsymmetrical alkene

Dr.Laila Al-Harbi

AlkynesAlkynes have the general formula CnH2n-2 where n = 2,3,4,…

• contain at least one carbon-carbon triple bond (sp)

1-butyne2-butyne

CH C CH2 CH3CH3 C C CH3

Production of acetylene

CaC2 (s) + 2H2O (l) → C2H2 (g) + Ca(OH)2 (aq)

Alkynes Reactions

1-Hydrogenation

CH ≡ CH (g) + H2 (g)→ CH2 ≡CH2 (g)

2-Addition Reactions

CH ≡ CH (g) + HBr (g) → CH2 ≡ CHBr (g)

CH ≡CHCH3 (g) + HBr (g) → CH2=CHCH3 (g)Br

-

3-oxidation

2C2H2 (g) + O2 (g)→ 4CO2 +2H2O

4-decomposition

C2H2 (g) → 2C(s) + H2 (g)

Dr.Laila Al-Harbi

C

CC

CC

C

H

H

H

H

H

H

C

CC

CC

C

H

H

H

H

H

H

Aromatic compound contain one or more benzene ring

Aromatic Compound Nomenclature

If one H atom has been replaced by another atom or a group of atom

>>the name of the atom or group then benzene

CH2CH3 Cl

chlorobenzene

NH2 NO2

nitrobenzeneethylbenzene aminobenzene

Dr.Laila Al-Harbi

Aromatic Compound Nomenclature

12

34

5

6

Br

Br

1,2-dibromobenzene

Br

Br

1,3-dibromobenzene

If more than one substituent is present >>we must indicate the location of the second

group relative to first then benzene

Br

Br

o-dibromobenzene m-dibromobenzene1,4-dibromobenzene

p-dibromobenzene

NO2

Br

m-bromonitrobenzene

CH3-CH-CH3

2-phenylpropane

Dr.Laila Al-Harbi

Aromatic Compound Reactions

H

H

H

H

H

H

Br

H

H

H

H

H

+ HBr+ Br2

FeBr3

catalyst

HH

H

H

HH

CH2CH3

H

H

H

HH

+ HCl+ CH3CH2ClAlCl3

catalyst

1- Substitution reaction

2- hydrogenation

Pt

catalyst

Dr.Laila Al-Harbi

Polymers are large molecules made up of repeating units

called Monomers

Proteins are polymers of amino acids ; they play a key role in

nearly all biological process. Proteins high molar mass;

ranging from about 5000 g.

The basic structural unit of protein is amino acids

Amino acid is a compound that contains at least one amino

group(-NH2) and at least one carboxyl group(-COOH)

C CH

H

NH2

O

OH

Dr.Laila Al-Harbi

Structure – an amino acid possesses both a carboxyl and an amino

group. The most common in the biological amino acids are the a-amino

acids. The amino acid exists as a dipolar ion , possessing both a positive

charge and a negative charge.

NH2

O

R

OHNH

3+

O

R

O

Dipolar ion

20 different amino acids are the building blocks of all proteins in the

human body

The amino group of one molecule condenses with the acid group of

another to gives Protein through peptide bonds

Dr.Laila Al-Harbi

Compounds Functional gp. Comments

1-alcohol R-OH

2-Ethers R-O-R’ R=R’ , R≠ R’

R (Hydrocarbon , aromatic )

3-ketone R=R’ , R≠ R’

R (Hydrocarbon , aromatic )

4-aldhyde

5-carboxilic acid

6- ester R=R’ , R≠ R’

R (Hydrocarbon , aromatic )

7- amine R3N R2NH , RNH2

8-Amino acid

Dr.Laila Al-Harbi

Term used to refer to parts of organic molecules where reactions tend to occur.

R - C - H

O=

R - C – R’

O=

R - C - OH

O=

R - C – OR’

O=

R-CH - C - OH

O=NH2-

Dr.Laila Al-Harbi

CH3 O CH2 CH3

CH3 CH2 NH2

CH3 CH2 C

O

H

CH3 C CH2 CH3

O

H C

O

OH

CH3 CH2CH2 OH

CH2 C

NH2

H

C

O

OH

(a)

(b)

(c)

(d)

(e)

(f)

(g)

(Ether)

(Amine)

(Aldehyde)

(Ketone)

(Carboxylic Acid)

(Alcohol)

(Amino Acid)