Propanal Information
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.
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Production
Propionaldehyde is mainly produced industrially through hydroformylation, by combining synthesis gas (carbon monoxide and hydrogen) with ethylene using a metal catalyst:
- CO + H2 + C2H4 → CH3CH2CHO
Laboratory preparation
In the laboratory, it may be prepared by refluxing a mixture of propanol, 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.[1]
Uses
It is principally used as a precursor to trimethylolethane (CH3C(CH2OH)3) through a condensation reaction with methanol; this triol is an important intermediate in the production of alkyd resins.
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.[2]
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.[3][4][5] To identify the propionaldehyde and the related compound propenal, researchers looked for the emission of specific frequencies of radio waves from the cloud. They did this because different types of molecules emit energy at different frequencies, each producing a unique signal that researchers can detect with powerful telescopes.
References
- ^ Charles D. Hurd and R. N. Meinert (1943), "Propionaldehyde", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0541 ; 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
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