| Description | Butanal, also known as butyral or butyl aldehyde, belongs to the class of organic compounds known as alpha-hydrogen aldehydes. These are aldehydes with the general formula HC(H)(R)C(=O)H, where R is an organyl group. It is miscible with most organic solvents. Butanal exists in all living organisms, ranging from bacteria to humans. Upon prolonged exposure to air, butyraldehyde oxidizes to form butyric acid. Butanal is an apple, bready, and chocolate tasting compound. Outside of the human body, Butanal is found, on average, in the highest concentration within cow milk and carrots. Butanal has also been detected, but not quantified in several different foods, such as hard wheats, borages, ostrich ferns, skunk currants, and fennels. This could make butanal a potential biomarker for the consumption of these foods. The dominant technology involves the use of rhodium catalysts derived from the water-soluble ligand Tppts. Butyraldehyde is produced almost exclusively by the hydroformylation of propylene:CH3CHCH2 + H2 + CO → CH3CH2CH2CHO. Traditionally, hydroformylation was catalyzed by cobalt carbonyl and later rhodium complexes of triphenylphosphine. At one time, it was produced industrially by the catalytic hydrogenation of crotonaldehyde, which is derived from acetaldehyde. Butyraldehyde can be produced by the catalytic dehydrogenation of n-butanol. This compound is the aldehyde derivative of butane. An aqueous solution of the rhodium catalyst converts the propylene to the aldehyde, which forms a lighter immiscible phase. About 6 billion kilograms are produced annually by hydroformylation. It is a colourless flammable liquid with an unpleasant smell. |
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