Propionaldehyde

Not to be confused with propanol.

Propanal

Flat structure
Ball-and-stick model
Names
IUPAC name Propanal
Systematic IUPAC name Propanal
Other names Propionaldehyde; Methylacetaldehyde; propionic aldehyde; propaldehyde
Identifiers
CAS Number	123-38-6 Y
ChEBI	CHEBI:17153 Y
ChEMBL	ChEMBL275626 Y
ChemSpider	512 Y
Jmol 3D model	Interactive image
PubChem	527
UNII	AMJ2B4M67V Y
UN number	1275
InChI InChI=1S/C3H6O/c1-2-3-4/h3H,2H2,1H3 Y Key: NBBJYMSMWIIQGU-UHFFFAOYSA-N Y InChI=1/C3H6O/c1-2-3-4/h3H,2H2,1H3 Key: NBBJYMSMWIIQGU-UHFFFAOYAZ
SMILES CCC=O
Properties
Chemical formula	C3H6O
Molar mass	58.08 g mol−1
Appearance	Colorless liquid Pungent, malty odor
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)
Solubility in water	20 g/100 mL
Viscosity	0.6 cP at 20 °C
Structure
Molecular shape	C1, O: sp2 C2, C3: sp3
Dipole moment	2.52 D
Vapor pressure	{{{value}}}
Related compounds
Related aldehydes	Acetaldehyde Butyraldehyde
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Propionaldehyde or propanal is the organic compound with the formula CH₃CH₂CHO. It is a saturated 3-carbon aldehyde and is a structural isomer of acetone. It is a colourless liquid with a slightly irritating, fruity odour.

Production

Propionaldehyde is mainly produced industrially through hydroformylation, by combining synthesis gas (carbon monoxide and hydrogen) with ethylene using a metal (typically rhodium) catalyst:

CO + H₂ + C₂H₄ → CH₃CH₂CHO

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

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.

Uses

It is principally 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. Other applications include reduction to propanol and oxidation to propionic acid.

Condensation of propionaldehyde with tert-butylamine gives CH₃CH₂CH=N-t-Bu, a three-carbon building block used in organic synthesis. Deprotonation of this imine with LDA produces CH₃CHLiCH=N-t-Bu, which in turn condenses with aldehydes.

Extraterrestrial occurrence

Astronomers have detected propionaldehyde (along with acrolein) in the molecular cloud Sagittarius B2 near the center of the Milky Way Galaxy, about 26,000 light years from Earth.

On 30 July 2015, scientists reported that upon the first touchdown of the Philae lander on comet 67/P's surface, measurements by the COSAC and Ptolemy instruments revealed sixteen organic compounds, four of which were seen for the first time on a comet, including acetamide, acetone, methyl isocyanate and propionaldehyde.