Editing Ethylene oxide (section)

==Molecular structure and properties==
[[File:Ethylene-oxide.png|250px|thumb|right|class=skin-invert-image]]
[[File:Ethylene oxide refrigerated liquid.jpg|thumb|right|Condensed ethylene oxide]]

The epoxy cycle of ethylene oxide is an almost regular triangle with bond angles of about 60° and a significant angular [[strain (chemistry)|strain]] corresponding to the energy of 105 kJ/mol.<ref>{{cite encyclopedia |chapter=Voltage molecules |title=Chemical Encyclopedia |editor=Knunyants, I. L. |encyclopedia=Soviet encyclopedia |year=1988 |volume=3 |pages=330–334}}</ref><ref name="traven">{{cite book |author=Traven VF |title=Organic chemistry: textbook for schools |editor=V. F. Traven |publisher=ECC "Academkniga" |year=2004 |volume=2 |pages=102–106 |isbn=5-94628-172-0}}</ref> For comparison, in [[alcohol (chemistry)|alcohols]] the C–O–H angle is about 110°; in [[ether]]s, the C–O–C angle is 120°. The [[moment of inertia]] about each of the principal axes are ''I<sub>A</sub>''={{val|32.921|e=-40|u=g·cm{{sup|2}}}}, ''I<sub>B</sub>''={{val|37.926|e=-40|u=g·cm{{sup|2}}}} and ''I<sub>C</sub>''={{val|59.510|e=-40|u=g·cm{{sup|2}}}}.<ref>{{cite journal |author=Cunningham G. L. |author2=Levan W. I. |author3=Gwinn W. D. |title=The Rotational Spectrum of Ethylene Oxide |journal=Phys. Rev. |year=1948 |volume=74 |issue=10 |page=1537 |bibcode=1948PhRv...74.1537C |doi=10.1103/PhysRev.74.1537}}</ref>

The relative instability of the carbon-oxygen bonds in the molecule is revealed by the comparison in the table of the energy required to break two C–O bonds in the ethylene oxide or one C–O bond in [[ethanol]] and [[dimethyl ether]]:<ref>{{cite book |title=Energy of chemical bonds. Ionization potentials and electron affinity |editor=Kondrat'ev, VN |publisher=Nauka |year=1974 |pages=77–78}}</ref>
{| Class="wikitable" style="text-align:center"
! Reaction
! ΔH°<sub>298</sub>, kJ/mol
! Method
|-
| '''{{chem2|(C2H4)O -> C2H4 + O}}''' (cleavage of two bonds)
| 354.38
| Calculated, from atomic enthalpies
|-
|'''{{chem2|[[Ethanol|C2H5OH]] -> C2H5 + OH}}''' (breaking one bond)
| 405.85
| Electron impact
|-
|'''{{chem2|[[Dimethyl ether|CH3OCH3]] -> CH3O + CH3}}''' (breaking one bond)
| 334.72
| Calculated using enthalpies of radicals formation
|}

This instability correlates with its high reactivity, explaining the ease of its [[ring-opening reaction]]s (see [[#Chemical properties|Chemical properties]]).