Propyne

Source: Wikipedia, the free encyclopedia.
Propyne
Methylacetylene
Names
Preferred IUPAC name
Other names
Methylacetylene
Methyl acetylene
Allylene
Identifiers
3D model (
JSmol
)
878138
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
100.000.754 Edit this at Wikidata
EC Number
  • 200-828-4
MeSH C022030
UNII
  • InChI=1S/C3H4/c1-3-2/h1H,2H3
    Key: MWWATHDPGQKSAR-UHFFFAOYSA-N
  • InChI=1/C3H4/c1-3-2/h1H,2H3
    Key: MWWATHDPGQKSAR-UHFFFAOYAI
  • CC#C
Properties
C3H4
Molar mass 40.0639 g/mol
Appearance Colorless gas[2]
Odor Sweet[2]
Density 0.53 g/cm3
Melting point −102.7 °C (−152.9 °F; 170.5 K)
Boiling point −23.2 °C (−9.8 °F; 250.0 K)
Vapor pressure 5.2 atm (20°C)[2]
Hazards
Explosive limits
1.7%-?[2]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1000 ppm (1650 mg/m3)[2]
REL (Recommended)
TWA 1000 ppm (1650 mg/m3)[2]
IDLH
(Immediate danger)
1700 ppm[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Propyne (methylacetylene) is an

gas welding. Unlike acetylene, propyne can be safely condensed.[3]

Production and equilibrium with propadiene

Propyne exists in equilibrium with propadiene, the mixture of propyne and propadiene being called MAPD:

The coefficient of equilibrium Keq is 0.22 at 270 °C or 0.1 at 5 °C. MAPD is produced as a side product, often an undesirable one, by

feedstock in the chemical industry.[3] MAPD interferes with the catalytic polymerization
of propene.

Laboratory methods

Propyne can also be synthesized on laboratory scale by reducing

vapors over magnesium.

Use as a rocket fuel

European space companies have researched using light

rocket fuel for craft intended for low Earth orbital operations. They reached this conclusion based upon a specific impulse expected to reach 370 s with oxygen as the oxidizer, a high density and power density—and the moderate boiling point, which makes the chemical easier to store than fuels that must be kept at extremely low temperatures. (See cryogenics
.)

Organic chemistry

Propyne is a convenient three-carbon building block for

carbonyl groups, producing alcohols and esters.[6] Whereas purified propyne is expensive, MAPP gas could be used to cheaply generate large amounts of the reagent.[7]

Propyne, along with

The chemical shift of an alkynyl proton and propargylic proton generally occur in the same region of the 1H NMR spectrum. In propyne, these two signals have almost exactly the same chemical shifts, leading to overlap of the signals, and the 1H NMR spectrum of propyne, when recorded in deuteriochloroform on a 300 MHz instrument, consists of a single signal, a sharp singlet resonating at 1.8 ppm.[9]

Notes

  1. ^ "Prop-1-yne" mistake fixed in the errata Archived 2019-08-01 at the Wayback Machine. The locant is omitted according to P-14.3.4.2 (d), p. 31.

References

  1. .
  2. ^ a b c d e f g NIOSH Pocket Guide to Chemical Hazards. "#0392". National Institute for Occupational Safety and Health (NIOSH).
  3. ^ ).
  4. . Retrieved 20 February 2014.
  5. ^ Reiser, Edward II. (1896). "The preparation of Allylene, and the Action of Magnesium upon Organic Compounds". The Chemical News and Journal of Industrial Science. LXXIV: 78–80. Retrieved 20 February 2014.
  6. ^ Michael J. Taschner; Terry Rosen; Clayton H. Heathcock (1990). "Ethyl Isocrotonate". Organic Syntheses; Collected Volumes, vol. 7, p. 226.
  7. ^ US patent 5744071, Philip Franklin Sims, Anne Pautard-Cooper, "Processes for preparing alkynyl ketones and precursors thereof", issued 1996-11-19 
  8. .
  9. .

External links