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Skeletal formula of propionaldehyde (propanal) Skeletal formula of propionaldehyde.svg
Skeletal formula of propionaldehyde (propanal)
Flat structure Propionaldehyde flat structure.png
Flat structure
IUPAC name
Preferred IUPAC name
Other names
  • Methylacetaldehyde
  • Propionic aldehyde
  • Propaldehyde
3D model (JSmol)
ECHA InfoCard 100.004.204 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 204-623-0
PubChem CID
RTECS number
  • UE0350000
UN number 1275
  • InChI=1S/C3H6O/c1-2-3-4/h3H,2H2,1H3 Yes check.svgY
  • CCC=O
Molar mass 58.080 g·mol−1
AppearanceColourless liquid
Odor Pungent, fruity
Density 0.81 g cm−3
Melting point −81 °C (−114 °F; 192 K)
Boiling point 46 to 50 °C (115 to 122 °F; 319 to 323 K)
20 g/100 mL
-34.32·10−6 cm3/mol
Viscosity 0.6 cP at 20 °C
C1, O: sp2

C2, C3: sp3

2.52 D
GHS pictograms GHS-pictogram-flamme.svg GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
GHS Signal word Danger
H225, H302, H315, H318, H332, H335 [1]
P210, P261, P280, P304+P340+P312, P305+P351+P338, P310, P403+P235 [1]
NFPA 704 (fire diamond)
Flash point −26 °C (−15 °F; 247 K)
175 °C (347 °F; 448 K)
Related compounds
Related aldehydes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)
Infobox references

Propionaldehyde or propanal is the organic compound with the formula CH3CH2CHO. It is the 3-carbon aldehyde. It is a colourless, flammable liquid with a slightly fruity odour. It is produced on a large scale industrially.



Propionaldehyde is mainly produced industrially by hydroformylation of ethylene:

CO + H2 + C2H4 → CH3CH2CHO

In this way, several hundred thousand tons are produced annually. [2]

Laboratory preparation

Propionaldehyde may also be prepared by oxidizing 1-propanol with a mixture of sulfuric acid and potassium dichromate. The reflux condenser contains water heated at 60 °C, which condenses unreacted propanol, but allows propionaldehyde to pass. The propionaldehyde vapor is immediately condensed into a suitable receiver. In this arrangement, any propionaldehyde formed is immediately removed from the reactor, thus it does not get over-oxidized to propionic acid. [3]


Propionaldehyde exhibits the reactions characteristic of alkyl aldehydes, e.g. hydrogenation, aldol condensations, oxidations, etc. It is the simplest aldehyde with a prochiral methylene such that α-functionalized derivatives (CH3CH(X)CHO) are chiral.


It is predominantly used as a precursor to trimethylolethane (CH3C(CH2OH)3) through a condensation reaction with formaldehyde. This triol is an important intermediate in the production of alkyd resins. It is used in the synthesis of several common aroma compounds (cyclamen aldehyde, helional, lilial). Other applications include reduction to propanol and oxidation to propionic acid. [2]

Laboratory uses

Propionaldehyde is a common reagent, being a building block to many compounds. [4] Many of these uses exploit its participation in condensation reactions. [5] [ verification needed ] With tert-butylamine it gives CH3CH2CH=N-t-Bu, a three-carbon building block used in organic synthesis. [6]

Extraterrestrial occurrence

Propionaldehyde along with acrolein has been detected in the molecular cloud Sagittarius B2 near the center of the Milky Way Galaxy, about 26,000 light years from Earth. [7] [8] [9]

Measurements by the COSAC and Ptolemy instruments on comet 67/P 's surface, revealed sixteen organic compounds, four of which were seen for the first time on a comet, including acetamide, acetone, methyl isocyanate and propionaldehyde. [10] [11] [12]


With an LD50 of 1690 mg/kg (oral), [2] propionaldehyde exhibits low acute toxicity.

Related Research Articles

Alkyne Acyclic hydrocarbon

In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are generally hydrophobic.

Ketone Class of organic compounds having structure RCOR

In chemistry, a ketone is a functional group with the structure R2C=O, where R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond). The simplest ketone is acetone (R = R' = methyl), with the formula CH3C(O)CH3. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids (e.g., testosterone), and the solvent acetone.

Ethanal (common name acetaldehyde) is an organic chemical compound with the formula CH3CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. Consumption of disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for the metabolism of acetaldehyde, thereby causing it to build up in the body.

A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.

In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group -COCl. Their formula is usually written RCOCl, where R is a side chain. They are reactive derivatives of carboxylic acids. A specific example of an acyl chloride is acetyl chloride, CH3COCl. Acyl chlorides are the most important subset of acyl halides.

Acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl functional group into a chemical compound. Such compounds are termed acetate esters or acetates. Deacetylation is the opposite reaction, the removal of an acetyl group from a chemical compound.

Acetamide (systematic name: ethanamide) is an organic compound with the formula CH3CONH2. It is the simplest amide derived from acetic acid. It finds some use as a plasticizer and as an industrial solvent. The related compound N,N-dimethylacetamide (DMA) is more widely used, but it is not prepared from acetamide. Acetamide can be considered an intermediate between acetone, which has two methyl (CH3) groups either side of the carbonyl (CO), and urea which has two amide (NH2) groups in those locations. Acetamide is also a naturally occurring mineral with the IMA symbol: Ace.

Nitro compound

Nitro compounds are organic compounds that contain one or more nitro functional groups (−‹The template Nitrogen is being considered for deletion.› NO2). The nitro group is one of the most common explosophores (functional group that makes a compound explosive) used globally. The nitro group is also strongly electron-withdrawing. Because of this property, C−H bonds alpha (adjacent) to the nitro group can be acidic. For similar reasons, the presence of nitro groups in aromatic compounds retards electrophilic aromatic substitution but facilitates nucleophilic aromatic substitution. Nitro groups are rarely found in nature. They are almost invariably produced by nitration reactions starting with nitric acid.

The Bouveault–Blanc reduction is a chemical reaction in which an ester is reduced to primary alcohols using absolute ethanol and sodium metal. It was first reported by Louis Bouveault and Gustave Louis Blanc in 1903. Bouveault and Blanc demonstrated the reduction of ethyl oleate and n-butyl oleate to oleyl alcohol. modified versions of which were subsequently refined and published in Organic Syntheses.

Iminium Functional group in organic chemistry

An iminium cation in organic chemistry is a functional group with the general structure [R1R2C=NR3R4]+. They are common in synthetic chemistry and biology.

Ethyl acetoacetate Chemical compound

The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds. It is used as a flavoring for food.

1,4-Benzoquinone Chemical compound

1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic or formaldehyde. This six-membered ring compound is the oxidized derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.

Propiophenone Chemical compound

Propiophenone is an aryl ketone. It is a colorless, sweet-smelling liquid that is insoluble in water, but miscible with organic solvents. It is used in the preparation of other compounds.

In nitrile reduction a nitrile is reduced to either an amine or an aldehyde with a suitable chemical reagent.

Jones oxidation

The Jones oxidation is an organic reaction for the oxidation of primary and secondary alcohols to carboxylic acids and ketones, respectively. It is named after its discoverer, Sir Ewart Jones. The reaction was an early method for the oxidation of alcohols. Its use has subsided because milder, more selective reagents have been developed, e.g. Collins reagent.

Hydroxylamine-<i>O</i>-sulfonic acid Chemical compound

Hydroxylamine-O-sulfonic acid ("HOSA") is the inorganic compound with molecular formula H3NO4S that is formed by the sulfonation of hydroxylamine with oleum. It is a white, water-soluble and hygroscopic, solid, commonly represented by the condensed structural formula H2NOSO3H, though it actually exists as a zwitterion and thus is more accurately represented as +H3NOSO3. It is used as a reagent for the introduction of amine groups (–NH2), for the conversion of aldehydes into nitriles and alicyclic ketones into lactams (cyclic amides), and for the synthesis of variety of nitrogen-containing heterocycles.


In organic chemistry, an ynone is a compound containing a ketone function and a C≡C triple bond. Many ynones are α,β-ynones, where the carbonyl and alkyne groups are conjugated. Capillin is a naturally occurring example. Some ynones are not conjugated.

Propionyl chloride Chemical compound

Propionyl chloride is the organic compound with the formula CH3CH2C(O)Cl. It is the acyl chloride derivative of propionic acid. It undergoes the characteristic reactions of acyl chlorides. It is a colorless, corrosive, volatile liquid.

(Chloromethylene)triphenylphosphorane is the organophosphorus compound with he formula Ph3P=CHCl (Ph = phenyl). It is a white solid but is usually generated and used in situ as a reagent in organic synthesis. It is structurally and chemically related to methylenetriphenylphosphorane.

Hydroxymethylation is a chemical reaction that installs the CH2OH group. The transformation can be implemented in many ways and applies to both industrial and biochemical processes.


  1. 1 2 Record of Propanal in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 22 March 2020.
  2. 1 2 3 Hensel, A. (2018). "Propanal". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_157.pub3.
  3. Hurd, Charles D.; Meinert, R. N. (1932). "Propionaldehyde". Organic Syntheses. 12: 64. doi:10.15227/orgsyn.012.0064.
  4. Wehrli, Pius A.; Chu, Vera (1978). "Y-Ketoesters from Aldehydes Via Diethyl Acylsuccinates: Ethyl 4-Oxohexanoate". Organic Syntheses. 58: 79. doi:10.15227/orgsyn.058.0079.
  5. Sessler, Jonathan L.; Mozaffari, Azadeh; Johnson, Martin R. (1992). "3,4-Diethylpyrrole and 2,3,7,8,12,13,17,18-Octaethylporphyrin". Org. Synth. 70: 68. doi:10.15227/orgsyn.070.0068.
  6. Peralta, M. M. "Propionaldehyde t-Butylimine" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi : 10.1002/047084289X.
  7. Scientists Discover Two New Interstellar Molecules: Point to Probable Pathways for Chemical Evolution in Space, National Radio Astronomy Observatory, June 21, 2004
  8. Two newly found space molecules. By: Goho, Alexandra, Science News, 00368423, 7/24/2004, Vol. 166, Issue 4
  9. Chemical Precursors to Life Found in Space Scientists say that a universal prebiotic chemistry may be at work
  10. Jordans, Frank (30 July 2015). "Philae probe finds evidence that comets can be cosmic labs". The Washington Post. Associated Press. Archived from the original on 23 December 2018. Retrieved 30 July 2015.
  11. "Science on the Surface of a Comet". European Space Agency. 30 July 2015. Retrieved 30 July 2015.
  12. Bibring, J.-P.; Taylor, M.G.G.T.; Alexander, C.; Auster, U.; Biele, J.; Finzi, A. Ercoli; Goesmann, F.; Klingehoefer, G.; Kofman, W.; Mottola, S.; Seidenstiker, K.J.; Spohn, T.; Wright, I. (31 July 2015). "Philae's First Days on the Comet - Introduction to Special Issue". Science . 349 (6247): 493. Bibcode:2015Sci...349..493B. doi: 10.1126/science.aac5116 . PMID   26228139.