''N''-Oxoammonium salts are a class of

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

s with the formula ₁R₂=O⁻. The cation ₁R₂=Ois of interest for the dehydrogenation of alcohols. Oxoammonium salts are diamagnetic, whereas the nitroxide has a doublet ground state. A prominent nitroxide is prepared by oxidation of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl, commonly referred to as EMPOsup>+. A less expensive analogue is Bobbitt's salt.

Structure and bonding

Oxoammonium cations are isoelectronic with

carbonyl In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a ...

s and structurally related to

aldoxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substitute ...

s (hydroxylamines), and

aminoxyl Aminoxyl denotes a radical functional group with general structure R2N–O•. It is commonly known as a nitroxyl radical or a nitroxide, however IUPAC discourages the use of these terms, as they erroneously suggest the presence of a nitro group. ...

(nitroxide) radicals, with which they can interconvert via a series of

redox Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...

steps. According to

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

, the N–O distance in EMPOF₄ is 1.184 Å, 0.1 Å shorter than the N–O distance of 1.284 Å in the charge-neutral TEMPO. Similarly, the N in EMPOsup>+ is nearly planar, but the O moves 0.1765 Å out of the plane in the neutral TEMPO. RedoxNitroxide

The ''N''-oxoammonium salts are used for oxidation of

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

s to

groups, as well as other forms of

oxoammonium-catalyzed oxidation Oxoammonium-catalyzed oxidation reactions involve the conversion of organic substrates to more highly oxidized materials through the action of an N-oxoammonium species. Nitroxides may also be used in catalytic amounts in the presence of a stoichi ...

s. The nitroxyl

TEMPO In musical terminology, tempo (Italian, 'time'; plural ''tempos'', or ''tempi'' from the Italian plural) is the speed or pace of a given piece. In classical music, tempo is typically indicated with an instruction at the start of a piece (often ...

reacts via its ''N''-oxoammonium salt.

References

{{DEFAULTSORT:Oxoammonium Salt, N- Functional groups Oxycations

Structure and bonding

See also

References