Propionaldehyde
| Propanal | |
|---|---|
 |
 |
 | |
| IUPAC name Propanal | |
| Systematic name Propionaldehyde | |
| Other names Methylacetaldehyde; propionic aldehyde; propaldehyde | |
| Identifiers | |
| CAS number | 123-38-6  |
| PubChem | 527 |
| ChemSpider | 512 |
| UNII | AMJ2B4M67V |
| UN number | 1275 |
| ChEBI | CHEBI:17153 |
| ChEMBL | CHEMBL275626 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular 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 |
| Hazards | |
| EU classification | Highly flammable (F) Irritant (Xi) |
| R-phrases | R11, R36/37/38 |
| S-phrases | S9, S16, S29 |
| NFPA 704 |
 3
2
2
|
| Flash point | −26 °C; −15 °F; 247 K |
| Autoignition temperature | 175 °C; 347 °F; 448 K |
| Related compounds | |
| Related aldehydes | Acetaldehyde Butyraldehyde |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
| 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.[1]
Laboratory preparation
Propionaldehyde may also be prepared by oxidizing 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.[2]
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.[1]
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.[3]
Interstellar occurrence
Astronomers have detected propionaldehyde in the molecular cloud Sagittarius B2 near the center of the Milky Way Galaxy, about 26,000 light years from Earth.[4][5][6] Because molecules emit energy at specific frequencies, researchers were able to identify propionaldehyde and the related compound, propenal, by measuring radio waves emitted by the cloud.
References
- ↑ 1.0 1.1 Anthony J. Papa "Propanal" In Ullmann's Encyclopedia of Industrial Chemistry, 2011, WIley-VCH, Weinheim. doi:10.1002/14356007.a22_157.pub2
- ↑ Charles D. Hurd and R. N. Meinert (1943), "Propionaldehyde", Org. Synth.; Coll. Vol. 2: 541
- ↑ Peralta, M. M. "Propionaldehyde t-Butylimine" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
- ↑ Scientists Discover Two New Interstellar Molecules: Point to Probable Pathways for Chemical Evolution in Space, National Radio Astronomy Observatory, June 21, 2004
- ↑ Two newly found space molecules. By: Goho, Alexandra, Science News, 00368423, 7/24/2004, Vol. 166, Issue 4
- ↑ Chemical Precursors to Life Found in Space Scientists say that a universal prebiotic chemistry may be at work