In organic chemistry, the acetoxy group (abbr. AcO or OAc; IUPAC name: acetyloxy[1]), is a functional group with the formula −OCOCH3 and the structure −O−C(=O)−CH3. As the -oxy suffix implies, it differs from the acetyl group (−C(=O)−CH3) by the presence of an additional oxygen atom. The name acetoxy is the short form of acetyl-oxy.
Functionality
[edit]An acetoxy group may be used as a protection for an alcohol functionality in a synthetic route although the protecting group itself is called an acetyl group.
Alcohol protection
[edit]There are several options of introducing an acetoxy functionality in a molecule from an alcohol (in effect protecting the alcohol by acetylation):
- Acetyl halide, such as acetyl chloride in the presence of a base like triethylamine[2]
- Activated ester form of acetic acid, such as a N-hydroxysuccinimide ester, although this is not advisable due to higher costs and difficulties.[3]
- Acetic anhydride in the presence of base with a catalyst such as pyridine with a bit of DMAP added.[4]
An alcohol is not a particularly strong nucleophile and, when present, more powerful nucleophiles like amines will react with the above-mentioned reagents in preference to the alcohol.[5]
Alcohol deprotection
[edit]For deprotection (regeneration of the alcohol)
- Aqueous base (pH >9)[6]
- Aqueous acid (pH <2), may have to be heated[7]
- Anhydrous base such as sodium methoxide in methanol. Very useful when a methyl ester of a carboxylic acid is also present in the molecule, as it will not hydrolyze it like an aqueous base would. (Same also holds with an ethoxide in ethanol with ethyl esters)[8]
See also
[edit]References
[edit]- ^ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 805. doi:10.1039/9781849733069-00648. ISBN 978-0-85404-182-4.
The systematic name 'acetyloxy' is preferred to the contracted name 'acetoxy' that may be used in general nomenclature.
- ^ Ouellette, Robert J.; Rawn, J. David (2019). "22 - Carboxylic Acid Derivatives". Organic Chemistry (2nd ed.). pp. 665–710. doi:10.1016/C2016-0-04004-4. ISBN 978-0-12-812838-1. Retrieved 2024-05-08.
- ^ Cali, Khasim; Tuccori, Elena; Persaud, Krishna C. (2020-08-19). "Chapter Eighteen - Gravimetric biosensors". In Pelosi, Paolo; Knoll, Wolfgang (eds.). Odorant Binding and Chemosensory Proteins. Methods in Enzymology. Vol. 642. pp. 435–468. doi:10.1016/bs.mie.2020.05.010. ISSN 0076-6879. Retrieved 2024-05-08.
{{cite book}}: CS1 maint: date and year (link) - ^ Nishihara, Shoko; Angata, Kiyohiko; Aoki-Kinoshita, Kiyoko F.; Hirabayashi, Jun, eds. (2021). Glycoscience Protocols (GlycoPODv2). Saitama (JP): Japan Consortium for Glycobiology and Glycotechnology. PMID 37590565.
- ^ Wall, Leo A.; Pummer, Walter J.; Fearn, James E.; Antonucci, Joseph M. (1963-09-01). "Reactions of polyfluorobenzenes with nucleophilic reagents" (PDF). Journal of Research of the National Institute of Standards and Technology. 67A (5): 481. doi:10.6028/jres.067A.050. ISSN 0022-4332. PMC 5319811. PMID 31580596.
- ^ Matyjaszewski, Krzysztof; Möller, Martin (2012). "8.03 - Photoresists and Advanced Patterning". Polymer Science: A Comprehensive Reference. Vol. 8. Elsevier Science. pp. 37–76. doi:10.1016/B978-0-444-53349-4.00201-6. ISBN 978-0-08-087862-1.
- ^ Howard, Kyle T.; Chisholm, John D. (2016-01-02). "Preparation and Applications of 4-Methoxybenzyl Esters in Organic Synthesis". Organic Preparations and Procedures International. 48 (1): 1–36. doi:10.1080/00304948.2016.1127096. ISSN 0030-4948. PMC 4989276. PMID 27546912.
- ^ Banyikwa, Andrew Toyi; Miller, Stephen E.; Krebs, Richard A.; Xiao, Yuewu; Carney, Jeffrey M.; Braiman, Mark S. (2017-10-31). "Anhydrous Monoalkylguanidines in Aprotic and Nonpolar Solvents: Models for Deprotonated Arginine Side Chains in Membrane Environments". ACS Omega. 2 (10): 7239–7252. doi:10.1021/acsomega.7b00281. ISSN 2470-1343. PMC 6645140. PMID 31457300.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction