Method for producing conjugated diene

A method for producing a conjugated diene, the method consisting of:

• reacting an α-olefin and formaldehyde with each other to produce a reaction liquid comprising a γ,δ-unsaturated alcohol;
• washing the reaction liquid to obtain a washed reaction liquid, wherein the washing comprises contacting the reaction liquid with an alkaline aqueous solution, and wherein the washed reaction liquid comprises an upper organic layer comprising the γ,δ-unsaturated alcohol;
• separating the upper organic layer from the washed reaction liquid to obtain a separated organic layer, then;
• distilling the separated organic layer to obtain a purified γ,δ-unsaturated alcohol;
• then
• subjecting the γ,δ-unsaturated alcohol to a dehydration reaction at 135 to 210° C. in the presence of an aqueous solution of an acidic catalyst, to obtain a conjugated diene, and
• optionally, purifying the conjugated diene.