Unit 3 Advanced Higher Learning outcomes
Organic Chemistry

Identify and give an example of the following type of reactions;
Substitution
Addition
Elimination
Condensation
Hydrolysis
Oxidation
Reduction

Be familiar with writing reaction mechanisms with curly arrows representing electron
shifts for the following reaction types;
Substitution of alkanes involving free radicals
Electrophilic addition to alkenes, both carbocation and cyclic ion intermediate
mechanisms.
Nucleophilic substitution, both SN1 and SN2
Hydrocarbons and Halogenoalkanes

Describe bonding in alkanes in terms of sp 3 hybridisation

Describe hybridisation as the process of mixing atomic orbitals in an atom to generate a
new set of atomic orbitals called hybrid orbitals.

Describe a sigma bond () as a covalent bond formed by end on overlap of two atomic
orbitals lying along the axis of a bond.

Identify the substitution reactions of alkenes as chain reactions with three distinct steps
in the mechanism;
1.Initiation by homolytic fission to produce radicals
2.propagation
3.termination

Describe bonding in ethene in terms of sp2 hybridisation

Describe a pi () bond as a covalent bond formed by the sideways overlap of two
parallel atomic orbitals lying perpendicular to the axis of the bond.

Preparation of alkenes
1. Dehydration of alcohols using aluminium oxide, conc. sulphuric acid or
orthphosphoric acid.
2. Base–induced elimination of hydrogen halides from monohalogenoalkanes.

Reactions of alkenes
1. Catalytic addition with hydrogen to form alkanes
2. Addition with halogens to form dihalogenoalkanes (cyclic ion intermediate)
3. Addition with hydrogen halides according to Markovnikov’s rule to form
monohalogenoalkanes. (carbocation intermediate)
4. Acid-catalysed addition with water according to Markovnikov’s rule to form alcohols
(carbocation intermediate)
Monohalogenoalkanes;
can be primary, secondary or tertiary,
undergo nucleophilic substitution reactions
undergo elimination reactions to form alkenes


Monohalogenoalkanes react with;
alkalis to form alcohols,
alcoholic alkoxides to form ethers
ammonia to form amines
ethanolic cyanide to form nitriles which can be hydrolysed to carboxylic acids
Alcohols

Properties of alcohols:
1.They exhibit hydrogen bonding and as a result have higher boiling points than
compounds of comparable formula mass and shape.
2.The lower alcohols are miscible with water but as their chain length increases, their
solubility in water decreases.

Preparation of alcohols;
1. hydration of alkenes
2. substitution of monohalogenoalkanes

Reactions of alcohols
1. They react with some reactive metals to form alkoxides
2. They can be dehydrated to form alkenes
3. They undergo condensation reactions with acids and more vigorously with acid
chlorides to form esters
Properties and characteristics of ethers

They have the general formula R-O-R’ where R and R’ are alkyl groups

They have lower boiling points than the corresponding isomeric alcohols due to lack of
hydrogen bonding.

They can hydrogen bond with water molecules, explaining the solubility in water of
some ethers of low formula mass.

They are highly flammable and on exposure to air may form explosive peroxides

They can be prepared by the reaction of Halogenoalkanes with alkoxides.

They are used as solvents since they are relatively inert chemically and will dissolve in
many organic compounds.