Preparation and Reactions of Furan

Preparation and Reactions of Furan | Chemical Properties of Furan

Preparations and Reactions of Furan

Furan is a oxygen containing five-membered planar heterocyclic compound with the formula C4H4O. it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a chloroform-like odor. In most of its reactions, it resembles benzene.

Preparation of Furan

Preparation of Furan from Mucic Acid

Dry distillation of mucic acid first gives Furoic acid which on decarboxylation by heating at 200-300°C gives Furan.
Preparation of Furan from Mucic Acid

Preparation of Furan from Furfural

By oxidation of furfural with potassium dichromate to give furoic acid which on decarboxylation by heating at 200-300°C gives Furan.
Preparation of Furan from Furfural

Preparation of Furan from Furfural (Commercial Method)

Decarboxylation of furfural in steam in the presence of silver oxide catalyst furan is obtained.
>Preparation of  Furan from Furfural (Commercial Method)

Preparation of Furan from Succinic dialdehyde


Dehydration of succinic dialdehyde by heating with P2O5 or ZnCl2.
Preparation of Thiophene from Sodium Succinate

Physical Properties of Furan

Furan is colorless liquid. Its boiling point is 31.4°C. It has an odour similar to Chloroform. It is insoluble in ether but soluble in most of the organic solvents.

Chemical Properties of Furan/Reactions of Furan

Resonance of Furan

Resonance of Thiophene

Basic Character of Furan

Furan, like pyrrole is a weak base. It forms unstable salts with mineral acids.

Electrophylic Substitution Reactions of Furan

Furan is an aromatic compound and more reactive than benzene. Because of the aromatic nature, furan gives all characteristic reactions (electrophilic substitution reactions) of aromatic compounds such as halogenation, nitration, sulphonation, Friedel-Crafts reactions etc.
Similar to pyrrole, furan also undergoes electrophilic substitution at the position Carbon-2. Approach of the electrophile at position Carbon-2 leads the formation of three resonating structures; however, only two resonating structures are obtained when the electrophile approaches at position Carbon-3.
Electrophilic Attack in Furan

Nitration of Furan

Furan is nitrated by solution of nitric acid in acetic anhydride to give 2-nitrofuran.
Nitration of Furan

Sulphonation of Furan

Furan reacts with sulfur trioxide – pyridine mixture in ethylene chloride at 100°C gives furan-2-sulphonic acid.
Sulphonation of Furan

Halogenation of Furan

Furan reacts vigorously with chlorine and bromine at room temperature to give polyhalogenated furan. For monohalogenated furan, much milder conditions to be used.
Halogenation of Furan

Friedel-Craft Acylation of Furan

Reaction of furan with acetic anhydride in presence of BF3 gives 2-acetylfuran.
Friedel-Craft Acylation of Furan

Mercuration of Furan

Furan undergoes mercuration with mercuric chloride in aqueous sodium acetate to produce 2-chloromercurifuran.
Mercuration of Furan

Reduction of Furan

Thiophene reduced under different conditions to give different products.
Reduction of Furan

Reaction of Furan with n-Butyl Lithium

Furan reacts with n-butyllithium in ether yields 2-furanlithium which when reacts with carbondioxide in HCl gives furan-2-carboxylic acid.
Reaction with n-Butyl Lithium of Furan

Reaction of Furan with Maleic Anhydride (Diels-Alder Reaction)

Furan reacts with maleic anhydride to form an addition product. Addition occurs at C-2 and C-5 positions.
Pyrrol and Thiophene does not give this reaction.
Reaction with Maleic Anhydride of Furan or Diels-Alder Reaction of Furan

Preparation and Reactions of Thiophene

Preparation and Reactions of Pyrrole