M4 Organic chem , synthesis , analytical techniques

Saturated & unsaturated

saturated -Single C-C bonds

Unsaturated - C=C double bond

Aliphatic, Aromatic & Alicyclic

Aliphatic -contains carbon and hydrogen joined together in a straight/branched/non aromatic rings

Alicyclic - non aromatic rings with or without side chains

Aromatic - containing benzene rings

Effect of branching on boiling points

Weaker induced dipole dipole interactions

Less surface contact

Less energy needed to overcome the intermolecular forces

Carbon monoxide

Toxic colourless odourless

Combined irreversibly with haemoglobin in the blood meaning oxygen cannot be transported around the body

Radical substitution (conditions & steps)

Reagents = reactants

Conditions = Ultra violet radiation (UV)

Initiation , Propagation , Termination

Homolytic fission - ADD DEFINITION

Limitation of radical substitution in organic synthesis

Further substitution occurs

Substitution at different positions in a carbon chain

Radical

Species with an unpaired electron

Stereoisomerism

Same structural formula different arrangement of atoms in space

Structural isomerism

Same molecular formula different structural formula

E/Z isomerism

Arises from having 2 different groups on each carbon atom of the carbon to carbon double bond (C=C)

Restricted rotation about the C=C

Hydrogenation

Test for alkene

Bromine water

Orange to colourless

Hydrogen halides

Hydration

Elimination (dehydration of an alcohol)

Heat under reflux

OH is removed from carbon 2 & H is removed from carbon 2 & produces Z&E but-2-ene + H2O

OH is removed from carbon 2 & H is removed from carbon 1 & produces but-2-ene + H2O

Substitution reactions of alcohols

Electrophilic Addition Mechanism

Heterolytic fission

Covalent bond breaks, one atom recieves both electrons

Reflux diagram

Distillation diagram

Primary alcohols (partial oxidation)

Potassium dichromate (K2Cr2O7) + Dilute sulfuric acid (H2SO4)

Heat under distillation

Primary alcohols (full oxidation)

Potassium dichromate (K2Cr2O7) + Dilute sulfuric acid (H2SO4)

Heat under reflux

Secondary alcohols

Potassium dichromate (K2Cr2O7) + Dilute sulfuric acid (H2SO4)

Heat under reflux

Hydrolysis of a haloalkane (nucleophilic substitution)

Aqueous alkali (NaOH)

Warm/Reflux

Heterolytic Fission - covalent bond breaks , one atom receives both electrons

Reactivity of haloalkanes

As we go from CF-CI

Bond enthalpies decrease (get weaker)

Easier to break carbon - halogen bond

Easier to lose halide ion

Haloalkanes become more reactive

Major/Minor products

Major product forms from the most stable carbocation

Secondary carbocation intermediate (2°)

Disadvantages (& solutions) of polymers

Carbon monoxide is a poison formed by incomplete combustion.(supply more oxygen ensures complete combustion)

Chlorine containing polymers burn to produce HCl which is corrosive & toxic (remove HCl by reacting with bases to neutralise the acid)

Where is the ozone layer located

Upper atmosphere

Effect of chlorine radicals on the ozone layer

Cl• + O3 → ClO• + O2

ClO• + O → Cl• + O2

O3 + O → 2O2

Effect of nitrous oxides on the ozone layer

NO• + O3 → NO2• + O2

NO2• + O → NO• + O2

O3 + O → 2O2

Conditions for depletion of ozone layer

UV Light

Destruction of oxone layer

Radicals from CFCS & NO(x) from thunderstorms or aircraft may catalyse the breakdown of ozone

Uses of infrared spectroscopy (IR)

Monitor air pollution by measuring concentration/abundance of atmospheric pollutants (CO & NO)

Breathalysers when testing drivers over alcohol limit