ORGANIC CHEMISTRY

What is organic chemistry?The study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.All living things are made from organic compounds based on chains of carbon atoms which are not only covalently bonded to each other but also covalently bonded to hydrogen, oxygen and/or other elements.

Fractional distillation of Crude Oil (Petroleum)

Fractional distillation of Crude Oil (Petroleum) Steps1. The crude oil is heated to 400 degrees, vaporizing all parts.2. Each fraction will contain hydrocarbons within a certain range of boiling points. Eg

petrol contains hydrocarbons between 30 and 110 degrees (between 5 and 10 carbons long).

3. The liquids condensing at different levels are collected on trays.4. These liquids may need further refining by more distillation.

Big hydrocarbons = high boiling points condense in the lower part of the tower. Small hydrocarbons = low boiling points condense in higher parts of the tower

Fractional distillation of Crude Oil (Petroleum) Properties

Hydrocarbons : compounds having hydrogen and carbon only.

Homologous series: a group of compounds which have the same general formula,

functional group, similar chemical properties but a trend in physical properties.

Isomerism: isomers are compounds having same molecular formula but different structural

formula. All the three compounds shown above are isomers of each other. They have the

same molecular formula C4H8, but they have different structures.

Alkanes

Alkenes

Alcohols

Organic Families

Carboxylic Acids

Basic Names

ALKANES

General formula is CnH2n+2 (n=1,2,3….)

They are saturated hydrocarbons: containing carbon-carbon single bonds.

The first 5 alkanes are gases at room temperature and pressure.

Physical properties: as the molecules get larger (carbon number increases)

1. Molecular mass increases.

2. Melting and boiling point increases.

3. Viscosity increases.

4. Flammability decreases.

Chemical properties: alkanes are generally unreactive as they are saturated

compounds.

1. Combustion: alkanes undergo complete and incomplete combustion producing

either CO 2, CO or C and water (H 2O) as products.

Example:

Complete combustionCH4(g) + 2O2(g) CO2(g) + 2H2O(g)

Incomplete combustion2CH4(g) + 3O2(g) 2CO(g) + 4H2O(g)

CH4(g) + 2O2(g) C (s) + 2H2O(g)

NAMING ALKANES

1- Select the longest chain of C atoms.2- place the ending -ANE on the basic

name

DRAWING ALKANES1- Draw all the C atoms in a straight chain

linked with single bonds.2- Surrounding each C atom, add as

many single bonds to ensure each C atom has FOUR bonds.

3- Add H atoms

2. Substitution reactions: alkanes undergo substitution reaction with halogens like, Br2,Cl2, and F2 in the presence of UV light or sunlight.

Example: 1) methane reacts with chlorine in the presence of UV light and form

four products. CH4(g) + Cl2(g) CH3Cl(g) + HCl(g)

A chain reaction takes place and other products are CH2Cl2, CHCl3 and CCl4

2) ethane reacts with fluorine in the presence of UV light and form six products.

C2H6(g) + F2(g) C2H5F(g) + HF(g)

A chain reaction takes place and other products are C2H4F2 C2H3F 3 and C2H2F 4, C2HF5 and C2F6.

The reaction with fluorine is faster than chlorine due to its reactivity increases

down the group.

CRACKING 1. To break up large hydrocarbon molecules into smaller ones to produce fuel for motor

vehicles.

2. It is also a means of producing alkenes.

3. Cracking is also a chemical reaction of producing hydrogen gas.

Conditions for crackingCracking is done by passing the hydrocarbon vapour over catalyst

Al2O3 or SiO2 at a temperature 5000C

Example:

C8H18

C2H4 + C6H14

2C3H6 + C2H6

2C2H4 + C4H8 + H2

ALKENEGeneral formula: CnH2n (n=2,3,4…)Alkenes are unsaturated hydrocarbons. Contains at least one carbon= carbon double bonds.

NAMING ALKENES

1- Select the longest chain of C atoms containing the double bond. 2- Place the ending -ENE on the basic name.3- use a number to indicate the lower number

DRAWING ALKANES1- Draw all the C atoms in a straight chain linked with one double bond and the rest as single bonds2- Surrounding each C atom, add as many single bonds to ensure each C atom has

Physical properties are similar to that of alkanes.

Chemical reactions: alkenes are more reactive than alkanes , due to the presence of

double bonds

NAMING ALKENES

1- Select the longest chain of C atoms containing the double bond. 2- Place the ending -ENE on the basic name.3- use a number to indicate the lower number

DRAWING ALKANES1- Draw all the C atoms in a straight chain linked with one double bond and the rest as single bonds2- Surrounding each C atom, add as many single bonds to ensure each C atom has

1. Combustion reactions similar to alkanesComplete combustionC2H4(g) + 3O2(g) 2CO2(g) + 2H2O(g)

Incomplete combustion2C2H4(g) + 4O2(g) 4CO(g) + 4H2O(g)

C2H4(g) + 2O2(g) 2C (s) + 2H2O(g)

2. Addition reactions:Alkenes undergo addition reactions, due to the presence of double bonds,

Hydrogenation: addition of hydrogen to form an alkane in the presence of nickel catalyst and temperature 1500C to 3000C (conditions).

- C2H4(g) + H2(g) C2H6 (g)

- vegetable oil + H2 margarine

Halogenation: addition of bromine to form a halo alkane

C2H4(g) + Br2(g) C2H4Br2 (g)

Test for unsaturation: adding bromine water to alkane will not decolourise(orange

colour remain same) where as with alkene the bromine water will decolourise from

orange to colourless.

Hydration :catalytic addition of steam to alkene will produce alcohol

Conditions: 3000c temperature, 60 atm and phosphoric acid catalyst

- C2H4(g) + H2O(g) C2H5OH (l)

Polymerization: Alkene undergo addition polymerization due to the presence of double

bonds.

Polyunsaturated: presence of many double bonds between

carbon -carbon atom

ALCOHOLGeneral formula : CnH2n+1OH ( n = 1,2,3….)Alcohol contains the hydroxyl group –OH as a functional group.Physical properties few members (C1 –C4) are liquids and soluble in water. solubility decreases as the carbon atom increases.

NAMING ALCOHOL

1- Select the longest chain of C atoms containing the –OH group.

2- Place the ending -OL on the basic name.

DRAWING ALCOHOL1- Draw all the C atoms in a straight chain linked with single bonds.2- Surrounding each C atom, add as many single bonds to ensure each C atom has FOUR bonds. 3- Add one OH group.4- Add H atoms to the remaining bonds

Chemical reactions : 1. Dehydration of alcohol produces alkenes. Conditions are concentrated sulfuric

acid at 1700C

C2H5OH (l) C2H4(g) + H2O(g)

2. Oxidation : alcohol on oxidation produces alkanoic acid or carboxylic acid. using

oxidisng agent like acidified potassium permanganate or acidified potassium

dichromate

Eg: C2H5OH (l) + 2[O] CH3COOH + H2O

H+/KMnO4 (colour changes from purple to colourless)

-C3H7OH (l) + 2[O] C2H5COOH + H2O

3. Reaction with metals: alcohols on reacting with metals it form alkoxide2C2H5OH (l) + 2Na 2C2H5ONa + H2

sodium ethoxide

Manufacture of ethanol

Fermentation of sugar Catalytic addition of steam to ethene

C6H12O6 2C2H5OH + 2CO2

Conditions: yeast as a catalyst

-C2H4(g) + H2O(g) C2H5OH

Conditions: 3000c temperature,

and a optimum temperature 370C -

420C,

-slow process

- 14% concentration.

- get poisoned keeping for a long

period of time.

- obtain from a renewable

resources

60 atm and phosphoric acid

catalyst

-fast process

- 100% concentration..

- obtain from a non renewable

resources

Uses of ethanol: 1. As a solvent for medicines, perfumes, detergents, dyes and varnishes.

2. As a fuel, either by itself or mixed with petrol in cars.

3. As a constituent in alcoholic drinks.

4. To make esters, perfumes, food essences

CARBOXYLIC ACID

PropertiesGeneral formula : CnH2n+1 COOH ( n = 0,1,2,3….)Carboxylic acid contains the carboxyl group –COOH as a functional group.

Physical properties few solids are soluble in water. solubility decreases as the carbon

atom increases.

Weak acids ionizes partially when dissolved in water

Eg:1. CH3COOH(aq) CH3COO- (aq) + H+ (aq)

Eg.2.

Chemical reactions : 1, Carboxylic acids reacts with metals, metal oxides, metal hydroxides, metal

carbonates and metal hydrogen carbonates to form salts

2CH3COOH(aq) + 2Na(s) 2CH3COONa(aq) + H2(g)

Sodium ethanoate

Ethanoate ion

2CH3COOH(aq) + MgO(s) (CH3COO)2Mg(aq) + H2O(l)

2CH3COOH(aq) + Ca(OH)2(aq) (CH3COO)2Ca(aq) + 2H2O(l)

2C2H5COOH(aq) + Na2CO3(s) 2C2H5COONa(aq) + H2O(l)

2. ESTERIFIATION: Esters are sweet smelling liquid acid which are formed when a

reaction took place between an alcohol and carboxylic acid . Conditions: concentrated sulfuric acid H2SO4 and heat

CH3COOH(aq) + C2H5OH CH3COOC2H5(aq) + H2O(l)

Uses of esters:1) Esters are used as solvent in the manufacture of liquors and in nail polish.

2) They are used to make food essences and perfumes.

POLYMERISATION Addition polymerization

Unsaturated compounds only undergo addition polymerization.

The double bonds in monomers break and they joined together to form a long chain.

calcium ethanoate

Sodium propanoate

magnesium ethanoate

Ethanoic aicd ethanol ethyl ethanoate

Monomer Polymer UsesName Formula Name Formula Ethene Polyethene

(Polythene)Plastic bags, sheets, bowls, film, etc.

Propene Polypropene Crates, plastic ropes,bottles,containers,etc

Chloroethene(vinyl chloride)

Polychloroethene (PVC or polyvinylchloride)

Water proof and insulating material, pipes and guttering ,records

Phenyl ethene(styrene)

Polyphenylethene(polystyrene)

Insulation Packaging, (foam)celing tiles

Tetra fluoroethene

Polytetrafluoroethene(PTFE or Teflon)

Non-stick sauce-pans,bridge bearings

Acrylonitrile

polyacrylonitrile

Synthetic fibre for carpet,clothes,etc.

methymethacrylate

Polymethymethacrylate(Perspex)

Glass subsitute

Condensation polymerizationCondensation polymerization is a process where two monomers react together to

produce a large molecule, with the elimination of a small molecule like water, (H2O), ammonia. (NH3), hydrogen chloride. HCl

Example:

1) Nylon: Amide linkage–CONH- is found in nylon Monomers used: Dicarboxylic acid and Diamine

HOOC— —COOH + NH2— —NH2

- H2O

(polyamide)

Properties and uses of nylonNylon is strong yet light. It can be stretched without breaking.It is woven into cloth to manufacture raincoats, parachutes and tents.Nylon is made into fibers to produce strong ropes, fishing lines and carpets.It is used to make curtain rail fittings cupboard hinges and gear wheels.

2) Protein: Amide linkage(-CONH-) is found in protein (natural polymer)

Monomers used: amino acids

- H2O

(p

polyamide/polypeptide)

Hydrolysis of Proteins

Proteins can be broken down into their constituent amino acids by hydrolysis (addition of water).Hydrolysis is carried out by heating the protein with a dilute acid or alkali or even enzymes. Protein + water HCl amino acids

+

TERYLENE: a ester( linkage is -COO-) is found in terylene

Monomers used: Dicarboxylic acid and Diol

HOOC— —COOH + HO — —OH

-H2O

Properties and uses of Terylene

Terylene is made into fibres which are woven into cloth. This polymer lasts longer than cotton. It is easier to wash and dry. Therefore polyester is used widely to produce clothes such as “T” shirts.

Terylene can also be used to produce films which are then used for making recording tapes.

Fat: Ester linkage(-COO-) is found in fats Monomers used: fatty acids and glycerol

Hydrolysis of fatsFats can be hydrolysed with an acid or alkali.Alkaline hydrolysis of fats is also called saponification. When fats are boiled with an alkali like sodium hydroxide.

+ 3NaOH +

Monomers used: diol

-H2O

n( C6H12O6) (C6H12O6)n + nH2O Glucose units Starch chain

Hydrolysis of carbohydrates-Carbohydrates can be broken down into simple sugars such as glucose by hydrolysis with warm acids or alkalis.

Advantages of plasticsThey can be easily shaped in single step by mould.Plastics are much more resistant to chemical environments than most metal, wood or paper products.Light weight and not corrode.

Disadvantages of plasticsThey are made from petrochemicals, which are finite source.

Pollution caused by plastics.Plastics are non bio degradable and cannot be decomposed by bacteria in the environment.Plastic objects accumulate and pollute the environment.They are carbon based polymers which burn to produce sooty flame and release toxic fumes like carbon monoxide and hydrogen chloride, HCl from PVC causing air pollution.