Housane

Summary

Housane or bicyclo[2.1.0]pentane is a saturated cycloalkane with the formula C5H8. It is a colorless volatile liquid at room temperature. It was named "housane" because of its shape. Structurally, the molecule consists of cyclopropane fused to cyclobutane. The synthesis of molecules containing multiple strained rings, such as housane, is a traditional endeavor in synthetic organic chemistry.

Housane
Housane.svg
Housane.png
Names
Preferred IUPAC name
Bicyclo[2.1.0]pentane
Identifiers
  • 185-94-4
3D model (JSmol)
  • Interactive image
ChemSpider
  • 8747
  • 9101
  • InChI=1S/C5H8/c1-2-5-3-4(1)5/h4-5H,1-3H2
    Key: MHLPKAGDPWUOOT-UHFFFAOYSA-N
  • InChI=1/C5H8/c1-2-5-3-4(1)5/h4-5H,1-3H2
    Key: MHLPKAGDPWUOOT-UHFFFAOYAN
  • C1C2CCC12
Properties
C5H8
Molar mass 68.119 g·mol−1
Appearance colorless liquid
Boiling point 45.5 ′C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

PreparationEdit

The first synthesis of housane was reported by Criegee in 1957, where housane was obtained from the pyrolysis of 2,3-diazabicyclo[2.2.1]hept-2-ene.[1]

 

Housane can be prepared in several steps starting with cyclopentadiene. Other methods include photolysis of 2,3-diazabicyclo[2.2.1]hept-2-ene, pyrolysis of N-Phenyl-2-oxo-3-azabicyclo[2.2.1]heptane, and addition of methylene to cyclobutene.[2]

Structure and propertiesEdit

The two rings are fused in a cis configuration—this meso compound formally has (1R,4S) absolute stereochemistry. The small size of the two rings prevents the trans isomer from existing, so the stereochemistry is not usually mentioned when discussing this structure.

Housane is easily attacked by bromine or iodine. In the presence of a platinum catalyst at room temperature, it is hydrogenated to cyclopentane. Reaction with hydrogen bromide at lower temperatures affords bromocyclopentane. Housane also reacts with lead tetraacetate, forming cis-1,3-diacetoxycyclopentane among other products.[1]

 

Housane is thermally quite stable, isomerizing to cyclopentene at 330 °C.[1]

ReferencesEdit

  1. ^ a b c Criegee, Rudolf; Rimmelin, Annemarie (1957). "Darstellung und Eigenschaften von Bicyclo‐[0.1.2]‐Pentan" [Preparation and Properties of Bicyclo-[0.1.2]-pentane]. Chemische Berichte. 90 (3): 414–417. doi:10.1002/cber.19570900319. ISSN 0009-2940.
  2. ^ P. G. Gassman, K. T. Mansfield "Bicyclo[2.1.0]pentane" Org. Synth. 1969, volume 49, pp. 1. doi:10.15227/orgsyn.049.0001