Editing Ketone (section)

==Characterization==
An aldehyde differs from a ketone in that it has a hydrogen atom attached to its carbonyl group, making aldehydes easier to oxidize. Ketones do not have a hydrogen atom bonded to the carbonyl group, and are therefore more resistant to oxidation. They are [[oxidized]] only by powerful [[oxidizing agents]] which have the ability to [[Bond cleavage|cleave]] carbon–carbon bonds.

===Spectroscopy===
Ketones (and aldehydes) absorb strongly in the [[infrared spectroscopy|infra-red spectrum]] near 1750 [[wavenumber|cm<sup>−1</sup>]], which is assigned to ν<sub>C=O</sub> ("carbonyl stretching frequency"). The energy of the peak is lower for aryl and unsaturated ketones.<ref>{{cite journal |last1=Smith |first1=Brian |title=The C=O Bond, Part VIII: Review |url=https://www.spectroscopyonline.com/view/co-bond-part-viii-review |website=Spectroscopy |series=November 2018 |date=November 2018 |volume=33 |pages=24–29 |access-date=12 February 2024 |archive-date=13 February 2024 |archive-url=https://web.archive.org/web/20240213050000/https://www.spectroscopyonline.com/view/co-bond-part-viii-review |url-status=live }}</ref>

Whereas [[Proton NMR|<sup>1</sup>H NMR]] [[spectroscopy]] is generally not useful for establishing the presence of a ketone, [[Carbon-13 NMR|<sup>13</sup>C NMR]] spectra exhibit signals somewhat downfield of 200 [[Parts-per notation#ppm|ppm]] depending on structure. Such signals are typically weak due to the absence of [[nuclear Overhauser effect]]s. Since aldehydes resonate at similar [[chemical shift]]s, multiple resonance experiments are employed to definitively distinguish aldehydes and ketones.

===Qualitative organic tests===
{{Redirect|Methyl ketone|the specific compound|acetone}}
Ketones give positive results in [[Brady's test]], the reaction with 2,4-dinitrophenylhydrazine to give the corresponding hydrazone. Ketones may be distinguished from aldehydes by giving a negative result with [[Tollens' reagent]] or with [[Fehling's solution]]. Methyl ketones give positive results for the [[iodoform test]].<ref>{{VogelQuantitative6th}}</ref> Ketones also give positive results when treated with ''m''-dinitrobenzene in presence of dilute sodium hydroxide to give violet coloration.