Propionaldehyde

Not to be confused with propanol.
Propionaldehyde
Names
IUPAC name
Propanal
Systematic IUPAC name
Propanal
Other names
  • Methylacetaldehyde
  • Propionic aldehyde
  • Propaldehyde
Identifiers
123-38-6 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:17153 YesY
ChEMBL ChEMBL275626 YesY
ChemSpider 512 YesY
ECHA InfoCard 100.004.204
PubChem 527
UNII AMJ2B4M67V YesY
UN number 1275
Properties
C3H6O
Molar mass 58.08 g·mol−1
Appearance Colorless liquid
Pungent, fruity 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)
20 g/100 mL
Viscosity 0.6 cP at 20 °C
Structure
C1, O: sp2

C2, C3: sp3

2.52 D
Hazards
F+ Xi
R-phrases R11, R36/37/38
S-phrases S9, S16, S29
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
3
2
2
Flash point −26 °C (−15 °F; 247 K)
175 °C (347 °F; 448 K)
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).
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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 colorless liquid with a slightly irritating, fruity odor.

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 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.[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]

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.[4][5][6]

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.[7][8][9]

References

  1. 1 2 Anthony J. Papa "Propanal" In Ullmann's Encyclopedia of Industrial Chemistry, 2011, WIley-VCH, Weinheim. doi:10.1002/14356007.a22_157.pub2
  2. ↑ Charles D. Hurd and R. N. Meinert (1943). "Propionaldehyde". Org. Synth.; Coll. Vol., 2, p. 541
  3. ↑ 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.
  4. ↑ Scientists Discover Two New Interstellar Molecules: Point to Probable Pathways for Chemical Evolution in Space, National Radio Astronomy Observatory, June 21, 2004
  5. ↑ Two newly found space molecules. By: Goho, Alexandra, Science News, 00368423, 7/24/2004, Vol. 166, Issue 4
  6. ↑ Chemical Precursors to Life Found in Space Scientists say that a universal prebiotic chemistry may be at work
  7. ↑ Jordans, Frank (30 July 2015). "Philae probe finds evidence that comets can be cosmic labs". The Washington Post. Associated Press. Retrieved 30 July 2015.
  8. ↑ "Science on the Surface of a Comet". European Space Agency. 30 July 2015. Retrieved 30 July 2015.
  9. ↑ 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. Retrieved 30 July 2015.
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