Chemistry- Organic 1

free radicals

atoms or groups of atoms which have a single unpaired electron.

How are free radicals formed?

when a bond splits easily by homolytic fission

What happens when alkanes under go free-radical substitution?

a hydrogen atom gets substituted by a halogen using UV

How do you draw mechanisms?

use half arrows

Homologous series

A series of organic compounds that have the same functional group but with each successive member differing by CH2

Functional group

A group of atoms responsible for the characteristic reactions of a compound

General formula for Alkanes

CnH2n+2

General formula for Alkenes

CnH2n

Saturated

only single bonds

Unsaturated

at least one double carbon bond

Addition

the reactants combine to form a single product

Substitution

one functional group is replaced by a different functional group

Oxidation

A species looses atleast one electron and is oxidised

Reduction

A species gains atleast one electron and is reduced

Polymerisation

A reaction in which many monomers join to form a polymer

Displayed formulae

shows every atom and bond seperately

Structural formulae

groups all the atoms joined to a particular carbon atom together

skeletal formula

A zig-zag line that only shows the bonds between carbon atoms

Molecular formulae

only shows the number of each type of atom in a molecule but not its structure

Empirical formulae

shows its molecular formula in its simplest ratio

Structural isomerism

same molecular formula, different structural formulae

Chain isomerism

molecules with different carbon chains

Position isomerism

molecules with the same functional group attached in different positions in the same carbon chain

Stereo isomers

same molecular formula and structural formula but different arrangements

Geometric isomers

Cis or trans or E/Z

Meth

1C

eth

2C

prop

3C

but

4C

pent

5C

hex

6C

Bio fuels

Fuels obtained from living matter that has died recently

Carbon neutrality

no carbon dioxide released

Biodiesel

found in vegetable oils

Bio alcohols

most common is bioethanol

Points to compare fuels

Land use, Yield, manufacturing and transport and carbon neutrality

Substitution reactions; formation of chloromethane

CH4 + Cl2 — CH3Cl +HCl

Substitution reactions; the formation of dichloromethane

CH3Cl + Cl2 — CH2Cl + HCl

Substitution reactions; the formation of trichloromethane

CH2Cl2 + Cl2 — CHCl3 + HCl

Substitution reactions; the formation of tetrachloromethane

CHCl3 + CCl4 + HCl

Chemical tests for a C=C bond formula (Addition of alkenes)

C2H4 + Br — C3H4Br

How do you test for a C=C bond?

Add bromine

Results for a colourless C=C bond test with bromine?

colourless if positive

Hydrogenation

an addition reaction in which hydrogen is added to an alkane

How does hydrogenation take place?

using nickel as a catalyst and heat

How is margarine formed?

unsaturated vegetable oils react with hydrogen to from a solid

What is the product of halogenation?

halogenoalkanes

Hydration

adding water

How is hydration done?

By adding steam and passing the mixture over a catalyst

What is the product of the addition of hydrogen halides

halogen alkane

Formula for addition of halogen halides

CH2=CH2 + H-Br — CH3 - CH3Br

How are alkanes converted into more helpful smaller hydrocarbons?

Fractional distillation, cracking and reforming

Fractional distillation

A process that relies on differences in the boiling temperature of the different hydrocarbons in crude oil

What is the trend boiling temperature in fractional distillation

longer chain and larger molecules = higher boiling temperature

What is the process of Fractional distillation?

Crude oil is heated in a furnace which turns it into vapour which is then passed through a series of bubble caps

What does Cracking do?

converts longer alkane chains into smaller hydrocarbon chains