ByNawaraj Kumar MahatoCOBASS +2 SCIENCE

Biratnagar

ORGANIC CHEMISTRY Organic chemistry is the study of carbon containing

compounds derived from living organisms.

Oil is formed over millions of years from the break down of dead creatures and plants.

80+ million compounds-

natural & synthetic.

Crude Oil (petroleum) is a mixture of many thousands of these different compounds and is the main source of many of these chemicals.

They are called hydrocarbons because they predominantly contain the elements hydrogen and carbon.

Distillation of Crude Oil

Distillation of Crude Oil

Homologous series

This is a series of compounds which all contain the same functional group, and have similar chemical properties. 

ALKANES ALKENES ALCOHOLS

CH4 CH2 =CH2 CH3OH

………………… …………………. ……………………

Each has a general formula:

ALKANES: …………………..

The members of the series differ by the number of CH2 units.

CH3-CH3, CH3-………-CH3, CH3-……………..-CH3

Graduation in physical properties:  eg: ………………..

CH4 (………), C8H18 (………….), C30H62 (……………)

Homologous series

This is a series of compounds which all contain the same functional group, and have similar chemical properties. 

ALKANES ALKENES ALCOHOLS

CH4 CH2 =CH2 CH3OH

CH3-CH3 CH2 =CH –CH3 CH3CH2OH

Each has a general formula:

ALKANES: CnH2n+2

The members of the series differ by the number of CH2 units.

CH3-CH3, CH3-CH2-CH3, CH3-CH2-CH2-CH3

Graduation in physical properties:  eg: boiling points.

CH4 (GAS), C8H18 (LIQUID), C30H62 (SOLID)

ALKANES SATURATED HYDROCARBONS – contain maximum

amount of ……………………………. - only ……………………….. bonds (no ……………………….. bonds)

GENERAL FORMULA …………………………

NAMING ALKANESNo of C atoms

Prefix

1

2

3

4

5

6

7

8

All alkanes end with ‘ANE’.

All belong to the same HOMOLOGOUS series

ALKANES SATURATED HYDROCARBONS – contain maximum

amount of hydrogen - only single bonds (no multiple bonds)

GENERAL FORMULA CnH(2n+2)

NAMING ALKANESNo of C atoms

Prefix

1 Meth

2 Eth

3 Prop

4 But

5 Pent

6 Hex

7 Hept

8 Oct

All alkanes end with ‘ANE’.

All belong to the same HOMOLOGOUS series

Alkenes

Esters

Amines

(alcohol)~yl

(acid)~oate

Amino -

CH3CONH2

Acylchlorides

Amides

~oyl Chloride

~amide

Aldehydes

Carboxylic Acids

~al

~oic acid

CH3- IHaloalkanes

Ketones

Halo~

~one

CH2 = CH2

Alcohols

~ene

~olFunctional

groups

The functional groups are

………………. or

………………….. of atoms which determine the

……………………. of organic molecules. 

Alkenes

Esters

Amines

(alcohol)~yl

(acid)~oate

Amino -

CH3CONH2

Acylchlorides

Amides

~oyl Chloride

~amide

Aldehydes

Carboxylic Acids

~al

~oic acid

CH3- IHaloalkanes

Ketones

Halo~

~one

CH2 = CH2

Alcohols

~ene

~olFunctional

groups

The functional groups are

atoms or

combinations of atoms which determine the

properties of organic molecules. 

STRUCTURES OF ALKANES

METHANE ……….

Bond Angle …………….

Shape ………………………

Can be illustrated as:

STRUCTURES OF ALKANES

METHANE CH4

Bond Angle 109.5o Shape Tetrahedral

Can be illustrated as:

H

H C H

H

ETHANE. Molecular formula …………...

Structural formula:……………………….. OR

………………… …………….

ETHANE. Molecular formula C2H6

Structural formula: CH3 CH3 or H H

H C C H

H H

PROPANE.

Both ethane and propane are “……………………” chain moleculesBUT!! Bonds are ……… 90o molecules are NOT…………….!!!

Schematic formula

....................formula: C3H8.....................formula: CH3 CH2 CH3 or H H H

H C C C H

H H H

PROPANE.

Molecular formula: C3H8Structural formula: CH3 CH2 CH3 or H H H

H C C C H

H H H

Both ethane and propane are “straight” chain moleculesBUT!! Bonds are NOT 90o molecules are NOT STRAIGHT!!!

Schematic formula

Molecular formula: ……………… - can have …………. different ………………………………

“Straight” chain. CH3 CH2 CH2 CH3BUTANE

Branched chain CH3 CH CH3

CH3

…………………………………….

IsomersIsomers

Compounds that have the same …………………….. formula but different ……………………………. formula.

BUTANE & ISOMERS.

Schematic formula

Molecular formula: C4H10 - can have two different structures

“Straight” chain. CH3 CH2 CH2 CH3 BUTANE

Branched chain CH3 CH CH3

CH3

METHYL PROPANE

IsomersIsomers

Compounds that have the same molecular formula but different structural formula.

branch

BUTANE & ISOMERS.

Schematic formula:

TASK:

Illustrate the structures of the three different isomers of C5H12.

Names & StructuresExamples2- methylbutane

CH3

CH3 CH CH2 CH3

CH3

CH3 C CH3

CH3

2,2 – dimethyl propane

TASK: illustrate the structures of:

2-methylpentane.

2,3 – dimethylbutane.

2,2,3 -trimethylpentane

CH3CH(CH3)CH2CH2CH3

CH3CH(CH3)CH(CH3)CH3

CH3C(CH3)2CH(CH3)CH2CH3

THE RULES FOR NAMING ORGANIC COMPOUNDS1. Choose the longest unbroken chain of Carbon atoms and assign a name

for the carbon chain using the prefixes; meth-1, eth-2 etc.

2. Identify any carbon chain branches (alkyl groups). These are assigned names using the same prefixes as above along with the suffix “-yl” – methyl, ethyl etc.

3. Identify the functional groups present in the molecule. Assign a prefix or suffix according to their homologous series. These will be written in front of the name of the carbon chain.

4. There is an order of precedence, to decide the suffix for the carbon chain:

COOH / C=C > OH > Br / Cl

5. Number the Carbon atoms in the longest chain so that the branches/functional groups have the lowest number possible. Allocate a number for every group/branch no matter how many times it occurs. Where groups are on the same carbon write their names in alphabetical order.

6. Numbering takes precedence "wins" over alphabetical spelling. Prefixes are used for groups that occur more than once.

Di – 2 Tri – 3 Tetra – 4 Penta – 5 etc.

7. The final name is written as one word with commas between numbers, hyphens separating numbers from words.

Give the names of the following alkanes(a)CH3 CH2 CH CH2 CH3

CH3

(b) CH3 CH CH2 CH CH3

CH3 CH3

(c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3

(d) CH3CH2CH(CH3)C(CH3)3

Give the names of the following alkanes

3-methyl pentane

2,4-dimethylpentane

2,2,4-trimethyl

hexane

(a)CH3 CH2 CH CH2 CH3

CH3

(b) CH3 CH CH2 CH CH3

CH3 CH3

(c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3

(d) CH3CH2CH(CH3)C(CH3)3 2,2,3-trimethylpentane

Cyclic Alkanes

C atoms can bond together to form a ‘ring’ – known as a ‘................................’ structure.

The molecular formula of this alkane?...........................Compare the molecular formula general formula for alkanes?.......................................It belong to the series of alkanes?...................................

Example

Illustrate the cyclic structures of (a) C4H8

and (b) C5H10 and name the molecules.

...................................

Can you think of a name for this molecule

Cyclic Alkanes

When C atoms bond together to form a ‘ring’ – known as a ‘cyclic’ structure.

What is the molecular formula of this alkane?

How does the molecular formula compare to the general formula for alkanes?Why does it belong to the series of alkanes?

Example

Illustrate the cyclic structures of (a) C4H8

and (b) C5H10 and name the molecules.

CYCLOHEXANE

Can you think of a name for this molecule

The shape around the double bond is …...................

The bond angle around the double bond is .................

C C bond

………………..

………..

Represented as C C

Structure of Alkenes

The shape around the double bond is planar.

The bond angle around the double bond is 120o

C C bond

PLANAR 120o

Represented as C C

Structure of Alkenes

Examples of Alkenes

………………, C2H4

H H

C C

H H

OR …………………….

PROPENE CH2 CH CH3

TASK: Use ball & stick models or sketches to construct and name 3 different structures for C4H8 each one with one double bond.

Examples of Alkenes

ETHENE, C2H4

H H

C C

H H

OR CH2 CH2

PROPENE CH2 CH CH3

TASK: Use ball & stick models or sketches to construct and name 3 different structures for C4H8 each one with one double bond.

CH3CH2CH CH2

CH3CH CHCH3

CH3C CH2

CH3

BUT-1-ENE

BUT-2-ENE

METHYL PROPENE

H H

C C

H CH3

More AlkenesIllustrate structures of the following alkenes:Pent-1-eneHex-3-ene

2-methylbut-1-ene

Cyclohexene

Name the following alkenesCH3CH CHCH2CH3

CH2 CHCH(CH3)CH2CH3CH3CH(CH3)CH CHCH2CH3(CH3)3CCH C(CH3)2

More AlkenesIllustrate structures of the following alkenes:Pent-1-eneHex-3-ene

2-methylbut-1-ene

Cyclohexene

CH2 CHCH2CH2CH3

CH3CH2CH CHCH2CH3

CH2 C(CH3)CH2CH3

Name the following alkenesCH3CH CHCH2CH3

CH2 CHCH(CH3)CH2CH3

Pent-2-ene3-methylpent-1-

eneCH3CH(CH3)CH CHCH2CH3

2-methylhex-3-ene

(CH3)3CCH C(CH3)2 2,4,4-trimethylpent-2-ene

GEOMETRIC ISOMERS There is ………………………….. about the double bond.

…………………………………….. isomerism is a form of STEREOISOMERISM –

Same molecular and structural formula but atoms are ……………………….. ……………………………………. in space.

……………………………………………… ISOMERISM each C atom in the double bond has two different atoms/groups attached.

BUT–2-ENE CH3 CH CH CH3

CH3 CH3

C C

H H

CH3 H

C C

H CH3

……… but-2-ene

……………. but-2-ene

GEOMETRIC ISOMERS There is no rotation about the double bond.

Geometric isomerism is a form of STEREOISOMERISM –

Same molecular and structural formula but atoms are arranged differently in space

GEOMETRIC ISOMERISM each C atom in the double bond has two different atoms/groups attached.

BUT–2-ENE CH3 CH CH CH3

CH3 CH3

C C

H H

CH3 H

C C

H CH3

cis but-2-enetrans but-2-ene

Alkynes

H-C≡C-H

H-C≡C-CH3

H-C≡C-CH2-CH3

CH3-C≡C-CH3

Ethyne

propyne

But–1-yne

But–2-yne

Very reactiveTriple bond unstable!Attracts electrophiles.

General formula CnH(2n+1)X

Substituted alkaneSubstituted alkane with at least one with at least one …………… …………… atomatom

Structures & Names

CH3Cl…………………………….1- bromopropane

2- iodobutane

General formula CnH(2n+1)X

Substituted alkaneSubstituted alkane with at least one with at least one halogen halogen atomatom

Structures & Names

CH3Cl chloromethaneCH3–CH2 –CH2Br 1- bromopropane

2- iodobutane CH3–CH–CH2 CH3

I

CH3–CH2–CH2–CH2Br PRIMARY 10

CH3–CH2–CH–CH3

Br

SECONDARY 20…………………………….

TERTIARY 30

………………………………………………..CH3 CH2–C–CH3

CH3

BrBr

………………………….

CH3–CH2–CH2–CH2Br PRIMARY 10

CH3–CH2–CH–CH3

Br

SECONDARY 202-bromobutane

TERTIARY 30

2-bromo-2-methylbutaneCH3 CH2–C–CH3

CH3

BrBr

1- bromobutane

General formula ……………………………….

•CH3OH …………………•CH3CH2OH ………………

•C3H7OH – two isomers

TASK: C4H9OH has 4 isomers. Draw the structures of each isomer giving the name and class of each one.

General formula CnH(2n+1)OH

•CH3OH Methanol •CH3CH2OH Ethanol

•C3H7OH – two isomers

CH3—CH2—CH2OH

Propan-1-ol 1o

Propan-2-ol 2o

CH3—CH—CH3

OH

TASK: C4H9OH has 4 isomers. Draw the structures of each isomer giving the name and class of each one.

Hydroxyl group

•FERMENTATION – ………………………………………………………………..C6H12O6

yeast ……………………….. +

…………..•HYDRATION OF ETHENECH2=CH2 + H2O

………………………………..Advantage Disadvantage

Fermentation

Hydration

Renewable sourcesLow

energyCheap

Batch

Slow

Impure/Low yieldFast

Pure

High yield /continuous

High energyNon-

renewableExpensive

•FERMENTATION – sugars (glucose)/yeast/25oC – 35OC C6H12O6

yeast 2C2H5OH + 2CO2

•HYDRATION OF ETHENECH2=CH2 + H2O CH3CH2OH

Advantage Disadvantage

Fermentation

Hydration

Renewable sourcesLow

energyCheap

Batch

Slow

Impure/Low yieldFast

Pure

High yield /continuous

High energyNon-

renewableExpensive

KNOWN AS ...................

STRUCTURE C O

BOND ANGLE ..............

ALDEHYDES

GENERAL STRUCTURE

R

C O

H

EXAMPLES

HCHO - .............................CH3CHO - ..................CH3CH2CHO - ................

Illustrate the structures of these examples

KNOWN AS CARBONYLS

STRUCTURE C O

BOND ANGLE 120O

ALDEHYDES

GENERAL STRUCTURE

R

C O

H

EXAMPLES

HCHO - methanalCH3CHO - ethanal

CH3CH2CHO - NAME?

Illustrate the structures of these examples

KETONES

GENERAL FORMULA....

C ....

.....

R and R1 may be the same or different

EXAMPLES

CH3COCH3 .......................CH3COCH2CH3 ..................

CH3CH2COCH2CH3 .........................

Illustrate the structures of these examples – show & name the corresponding aldehyde isomer.

NOTE: ALDEHYDES & KETONES EXHIBIT ............... .............ISOMERISM

KETONES

GENERAL FORMULAR

C O

R1

R and R1 may be the same or different

EXAMPLES

CH3COCH3 propanoneCH3COCH2CH3 butanoneCH3CH2COCH2CH3 pentan-3-one

Illustrate the structures of these examples – show & name the corresponding aldehyde isomer.

NOTE: ALDEHYDES & KETONES EXHIBIT FUNCTIONAL GROUP ISOMERISM

Carboxylic Acids

GENERAL FORMULA

EXAMPLESHCOOH ................... acidCH3COOH .................... acidCH3CH2COOH .......................... acid

Illustrate the structures of these examples – show & name the corresponding aldehyde isomer.

Acidic reaction

CH3COOH + H2O ……………………………. + H3O+

R

C O

OH

Carboxyl group

-COOH

Carboxylic Acids

GENERAL FORMULA

EXAMPLESHCOOH methanoic acidCH3COOH ethanoic acidCH3CH2COOH propanoic acid

Illustrate the structures of these examples – show & name the corresponding aldehyde isomer.

Acidic reaction

CH3COOH + H2O CH3COO- + H3O+

R

C O

OH

Carboxyl group

-COOH

FORMATION OF ESTERS• GENERALLY: .........+ ........... ESTER + WATER catalysed by H+ ions normally from conc. H2SO4

O O R C + H O R/ R C + H2O

OH O R/

O OH C + CH3OH H C + H2O

OH O CH3

methanoic methanol ............. ..........................

CH3CH2OH + CH3CH2COOH CH3CH2........CH2CH3 + H2O

ethanol propanoic ............ .........................

FORMATION OF ESTERS• GENERALLY: ACID + ALCOHOL ESTER + WATER catalysed by H+ ions normally from conc. H2SO4

O O R C + H O R/ R C + H2O

OH O R/

O OH C + CH3OH H C + H2O

OH O CH3

methanoic methanol methyl methanoate

CH3CH2OH + CH3CH2COOH CH3CH2COOCH2CH3 + H2O

ethanol propanoic ethyl propanoate

NAMING OF ESTERSGENERALLY:

ACID + ALCOHOL ESTER + WATER

ESTER NAME: .......................YL ............ANOATE

CH3CH2OH + CH3CH2COOH CH3CH2COOCH2CH3 +H2O

ethanol propanoic .........yl ............anoate

methanoic methanol..............hyl ..........anoate

NAMING OF ESTERSGENERALLY:

ACID + ALCOHOL ESTER + WATER

ESTER NAME: ALCOHOLYL ACIDANOATE

CH3CH2OH + CH3CH2COOH CH3CH2COOCH2CH3 +H2O

ethanol propanoic ETHyl PROPanoate

methanoic methanol METHyl METHanoate

HYDROLYSIS OF ESTERS• Hydrolysis can take place in either acid or alkaline

solution• Hot alkaline solution is usually preferred• Ester is hydrolysed to alcohol and sodium salt of

acid. Generally RCOOR’ + NaOH ROO-Na+ + R’OH

EXAMPLESCH3COOCH2CH3 + NaOH CH3COO-Na+ + CH3CH2OH

ethyl ethanoate sodium ethanoate ethanolCH3CH2COOCH3 + NaOH CH3CH2COO-Na+ + CH3OH

methyl propanoate sodium propanoate methanol

• Addition of dil.H2SO4 or dil. HCl to sodium salt regenerates the carboxylic acid.

USES OF ESTERS

esters have characteristic sweet smells and are used as food .................

they are also widely used as ............

and as ...................

USES OF ESTERS

esters have characteristic sweet smells and are used as food flavourings.

they are also widely used as solvents

and as plasticisers

NATURALLY OCCURING ESTERS

• Occur as fats and oils, known as triglycerides• Triesters of long-chain carboxylic acid and

propane –1,2,3-triol (glycerol).• On hydrolysis using hot NaOH, 3 moles of long

chain acid are produced together with 1 mole of glycerol.

C17H35COOCH2 CH2OH

C17H35COOCH + 3NaOH CHOH + 3C17H35COONa

C17H35COOCH2 CH2OH sodium

glycerol stearateSodium stearate is used in the manufacture of

soap.

AMINES

NC

H

HH

H

H

N H

H

H

N

H

H

H

NC

HH

H

H

H

AMIDESO

NCC

H

HH

H

H

C

O

NCC

H

H

H

H

H

HH C

O

NCC

H

C

H

H

H

HH

H

HH

Physical PropertiesRecognize and apply to particular examples the relationship between melting

points, boiling points, vapour pressure, viscosity and intermolecular forces (hydrogen bonding, Van der Waals forces including dispersion or London forces number and type of functional group, chain length, branched chains)

Addition reactions• Unsaturated compounds undergo addition reactions to form saturated

compounds e.g.

CH2=CH2 + Cℓ2 → CH2Cℓ-CH2Cℓ -

• hydrohalogentaion - addition of HX - halogenation - addition of X2 –

• hydration - addition of H2O –

• The X-atom or OH-group attaches to the more substituted C-atom.)

• hydrogenation - addition of H2 (During additon of HX and H2O to unsaturated hydrocarbons, the H-atom attaches to the C-atom already having the greater number of H-atoms. ·    

Elimination reactions• * Saturated compounds (haloalkanes, alcohols, alkanes) undergo

elimination reactions to form unsaturated compounds e.g. CH2Cℓ-CH2Cℓ → CH2=CHCℓ + HCℓ

• - dehydrohalogentaion - elimination of HX from a haloalkane (alkene with the more highly substituted double bond is the major product). –

• dehydration - elimination of H2O from an alcohol (alkene with the more highly substituted double bond is the major product). –

• dehydrogenation - elimination of H2 from an alkane. - cracking of alkanes. ·     

Substitution reactions• * Reactions of HX with alcohols e.g. (CH3)3OH + HBr → (CH3)3Br

+ H2O

• Reactions where the OH of alcohols are substituted with a halogen e.g. (CH3)3Br + KOH → (CH3)3OH + KBr

• Two types of saturated structure can be inter-converted by substitution as shown in the above two reaction equations.

• * Reactions of X2 with alkanes in the presence of light (prior knowledge from Grade 11).