4-Acetamido-TEMPO

4-Acetamido-TEMPO
Names
	Preferred IUPAC name (4-acetamido-2,2,6,6-tetramethylpiperidin-1-yl)oxyl
Identifiers
CAS Number	14691-89-5;
ECHA InfoCard	100.102.239
PubChem CID	518988;
CompTox Dashboard (EPA)	DTXSID60932959 ;
Properties
Chemical formula	C11H21N2O2
Molar mass	213.30 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

4-acetamido-TEMPO (short for (4-acetamido-2,2,6,6-tetramethylpiperidin-1-yl)oxyl) is a stable radical used for oxidation reactions in organic chemistry. It is a derivative of TEMPO, from which it differs by the additional acetamide group.

Preparation

4-acetamido-TEMPO can be prepared from 4-amino-2,2,6,6-tetramethylpiperidine. By reaction with acetic anhydride, the amino group is acetylated, and an acetate salt is formed. The free base can be regenerated with potassium carbonate. Oxidation to the nitroxyl radical occurs with hydrogen peroxide in the presence of sodium tungstate and ethylenediaminetetraacetic acid.^[1]

Properties

4-acetamido-TEMPO is a stable radical and exists as a crystalline, orange-colored solid.^[2]

Reactions

4-acetamido-TEMPO is suitable as a catalyst for oxidation reactions. This includes the oxidation of primary amines to nitriles with potassium peroxymonosulfate as the stoichiometric oxidizing agent.^[3] Additionally, it can be used to oxidize alcohols to aldehydes and ketones.^[1] A closely related reagent is the Bobbitt's salt, an oxidized derivative of 4-acetamido-TEMPO.^[2] The Bobbitt salt can be prepared starting from 4-acetamido-TEMPO by reacting it first with tetrafluoroboric acid and then with sodium hypochlorite.^[4]

References

^ ^a ^b Zhenkun Ma, James M. Bobbitt (October 1991), "Organic oxoammonium salts. 3. A new convenient method for the oxidation of alcohols to aldehydes and ketones", The Journal of Organic Chemistry, vol. 56, no. 21, pp. 6110–6114, doi:10.1021/jo00021a027
^ ^a ^b Jean M. Bray, Shannon M. Stephens, Shayne M. Weierbach, Karen Vargas, Kyle M. Lambert (2023), "Recent advancements in the use of Bobbitt's salt and 4-acetamidoTEMPO", Chemical Communications, vol. 59, no. 95, pp. 14063–14092, doi:10.1039/D3CC04709A{{citation}}: CS1 maint: multiple names: authors list (link)
^ Kyle M. Lambert, James M. Bobbitt, Sherif A. Eldirany, Liam E. Kissane, Rose K. Sheridan, Zachary D. Stempel, Francis H. Sternberg, William F. Bailey (2016-04-04), "Metal‐Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles", Chemistry – A European Journal, vol. 22, no. 15, pp. 5156–5159, doi:10.1002/chem.201600549{{citation}}: CS1 maint: multiple names: authors list (link)
^ James M. Bobbitt, Nicholas A. Eddy, Clyde X. Cady, Jing Jin, Jose A. Gascon, Svetlana Gelpí-Dominguez, Jerzy Zakrzewski, Martha D. Morton (2017-09-15), "Preparation of Some Homologous TEMPO Nitroxides and Oxoammonium Salts; Notes on the NMR Spectroscopy of Nitroxide Free Radicals; Observed Radical Nature of Oxoammonium Salt Solutions Containing Trace Amounts of Corresponding Nitroxides in an Equilibrium Relationship", The Journal of Organic Chemistry, vol. 82, no. 18, pp. 9279–9290, doi:10.1021/acs.joc.7b00846{{citation}}: CS1 maint: multiple names: authors list (link)

[:0-1] Zhenkun Ma, James M. Bobbitt (October 1991), "Organic oxoammonium salts. 3. A new convenient method for the oxidation of alcohols to aldehydes and ketones", The Journal of Organic Chemistry, vol. 56, no. 21, pp. 6110–6114, doi:10.1021/jo00021a027

[:1-2] Jean M. Bray, Shannon M. Stephens, Shayne M. Weierbach, Karen Vargas, Kyle M. Lambert (2023), "Recent advancements in the use of Bobbitt's salt and 4-acetamidoTEMPO", Chemical Communications, vol. 59, no. 95, pp. 14063–14092, doi:10.1039/D3CC04709A{{citation}}: CS1 maint: multiple names: authors list (link)

[3] Kyle M. Lambert, James M. Bobbitt, Sherif A. Eldirany, Liam E. Kissane, Rose K. Sheridan, Zachary D. Stempel, Francis H. Sternberg, William F. Bailey (2016-04-04), "Metal‐Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles", Chemistry – A European Journal, vol. 22, no. 15, pp. 5156–5159, doi:10.1002/chem.201600549{{citation}}: CS1 maint: multiple names: authors list (link)

[4] James M. Bobbitt, Nicholas A. Eddy, Clyde X. Cady, Jing Jin, Jose A. Gascon, Svetlana Gelpí-Dominguez, Jerzy Zakrzewski, Martha D. Morton (2017-09-15), "Preparation of Some Homologous TEMPO Nitroxides and Oxoammonium Salts; Notes on the NMR Spectroscopy of Nitroxide Free Radicals; Observed Radical Nature of Oxoammonium Salt Solutions Containing Trace Amounts of Corresponding Nitroxides in an Equilibrium Relationship", The Journal of Organic Chemistry, vol. 82, no. 18, pp. 9279–9290, doi:10.1021/acs.joc.7b00846{{citation}}: CS1 maint: multiple names: authors list (link)

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