Editing Acetic anhydride (section)

==Structure and properties==
[[File:Acetic anhydride.jpg|thumb|left|Acetic anhydride in a glass bottle]]
Acetic anhydride, like most organic acid anhydrides, is a flexible molecule with a nonplanar structure. The C=O and C-O distances are 1.19 and 1.39 Å.<ref>{{Citation | doi = 10.1107/S2053229616015047 | title = Acetic anhydride at 100 K: the first crystal structure determination | year = 2016 | last1 = Seidel | first1 = R. W. | last2 = Goddard | first2 = R. | last3 = Nöthling | first3 = N. | last4 = Lehmann | first4 = C. W. | journal = Acta Crystallographica Section C | volume = 72 | issue = 10 | pages = 753–757 | pmid = 27703123 | postscript = .}}</ref> The [[Pi bond|pi system linkage]] through the central oxygen offers very weak resonance stabilization compared to the [[dipole|dipole-dipole]] repulsion between the two [[carbonyl]] oxygens. The energy barriers to bond rotation between each of the optimal aplanar conformations are quite low.<ref>{{Citation | doi = 10.1021/jp993131z | title = Acetic Anhydride in the Gas Phase, Studied by Electron Diffraction and Infrared Spectroscopy, Supplemented with ab Initio Calculations of Geometries and Force Fields | year = 2000 | last1 = Wu | first1 = Guang | last2 = Van Alsenoy | first2 = C. | last3 = Geise | first3 = H. J. | last4 = Sluyts | first4 = E. | last5 = Van Der Veken | first5 = B. J. | last6 = Shishkov | first6 = I. F. | last7 = Khristenko | journal = The Journal of Physical Chemistry A | volume = 104 | issue = 7 | pages = 1576–1587 | bibcode = 2000JPCA..104.1576W | postscript = .}}</ref>