Butyraldehyde, also known as butanal, is an
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
with the formula CH
3(CH
2)
2CHO. This compound is the
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
derivative of
butane. It is a colorless flammable
liquid with an unpleasant smell. It is miscible with most organic solvents.
Production
Butyraldehyde is produced almost exclusively by the
hydroformylation
Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon d ...
of
propylene
Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petro ...
:
: CH
3CH=CH
2 + H
2 + CO → CH
3CH
2CH
2CHO
Traditionally, hydroformylation was catalyzed by
cobalt carbonyl
Dicobalt octacarbonyl is an organocobalt compound with composition . This metal carbonyl is used as a reagent and catalyst in organometallic chemistry and organic synthesis, and is central to much known organocobalt chemistry. It is the parent me ...
and later
rhodium
Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring i ...
complexes of
triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists ...
. The dominant technology involves the use of rhodium catalysts derived from the water-soluble ligand
tppts. 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. Butyraldehyde can be produced by the catalytic
dehydrogenation
In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...
of
''n''-butanol. At one time, it was produced industrially by the catalytic
hydrogenation
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organ ...
of
crotonaldehyde
Crotonaldehyde is a chemical compound with the formula CH3CH=CHCHO. The compound is usually sold as a mixture of the ''E''- and ''Z''-isomers, which differ with respect to the relative position of the methyl and formyl groups. The ''E''-isomer ...
, which is derived from
acetaldehyde.
Reactions
Butyraldehyde undergoes reactions typical of alkyl
aldehyde
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...
s, and these define many of the uses of this compound. Important reactions include
hydrogenation
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organ ...
to the alcohol,
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
to the acid, and base-catalyzed condensation.
Uses
Aldol condensation
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to ...
in the presence of a base forms 2-ethyl-2-hexenal, which is then hydrogenated to form
2-ethylhexanol
2-Ethylhexanol (abbreviated 2-EH) is an organic compound with formula CHO. It is a branched, eight-carbon chiral alcohol. It is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. It is produced on a large scal ...
, a precursor to the plasticizer
bis(2-ethylhexyl) phthalate.
Butyraldehyde is a precursor in the two-step synthesis of
trimethylolpropane 300 C-->
Trimethylolpropane (TMP) is the organic compound with the formula CH3CH2C(CH2OH)3. This colourless to white solid with a faint odor is a triol. Containing three hydroxy functional groups, TMP is a widely used building block in the polyme ...
, which is used for the production of
alkyd resins.
References
External links
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Flavors
Aldehydes
Foul-smelling chemicals