Nicotinic acid N oxide
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| Surname | Nicotinic acid N-oxide | ||||||||||||||||||
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| Molecular formula | C 6 H 5 NO 3 | ||||||||||||||||||
| Brief description |
white to yellowish red crystal powder |
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| Molar mass | 139.11 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| solubility |
Slightly soluble in cold, very easily soluble in hot water, in hot methanol and hot glacial acetic acid |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Nicotinic acid N oxide is a derivative of the pyridine N -oxide , one in the 3-position carboxy group carries. The most important use of 3-pyridine carboxylic acid-1-oxide as a starting material for 2-chloronicotinic that several major drugs and pesticides is based.
Occurrence and representation
The synthesis of nicotinic acid- N -oxide from nicotinic acid and 30% hydrogen peroxide in glacial acetic acid by heating at 100 ° C. for 3 h was reported in a short note in 1949 .
The reaction gives the end product in a yield of 70-80%.
Nicotinic acid- N -oxide is also accessible by oxidation of nicotinic acid amide with meta- chloroperbenzoic acid and subsequent hydrolysis of the amide group or, less risky, by oxidation of nicotinic acid methyl ester with carbamide peroxide UHP in formic acid and subsequent hydrolysis of the ester group .
properties
Nicotinic acid- N -oxide is a beige-colored solid that crystallizes as a pure substance in yellowish to white needles. The compound is very easily soluble in hot water and methanol, less readily in ethanol and insoluble in non-polar solvents such as e.g. B. petroleum ether or chloroform .
Applications
The most important application of nicotinic acid N -oxide is as a precursor of 2-chloronicotinic acid, which is produced by reacting with phosphorus oxychloride POCl 3 in excess and - based on 3-pyridinecarboxylic acid 1-oxide - equimolar amounts of the base triethylamine NEt 3 .
Under the reaction conditions, the N -oxide is reduced, and yields of 2-chloronicotinic acid of 65 to 70% are achieved.
2-chloronicotinic acid is the starting compound for the non-steroidal anti-inflammatory drug niflumic acid and its metabolic precursor ( prodrug ) Morniflumate, for which in the veterinary medicine employed non-opioid analgesic , flunixin and antiviral nevirapine , also for the herbicides diflufenican and nicosulfuron , as well as the fungicide boscalid .
Individual evidence
- ↑ a b c Entry on Nicotinic Acid N-oxide at TCI Europe, accessed on January 7, 2020.
- ↑ a b c d G.R. Clemo, H. Koenig: Notes: The N-oxides of nicotinic acid and its esters . In: J. Chem. Soc. 1949, p. 231-232 , doi : 10.1039 / JR949000S228 .
- ^ William M. Haynes: CRC Handbook of Chemistry and Physics, 97th Edition . CRC Press, Boca Raton, FL, USA 2017, ISBN 978-1-4987-5429-3 , pp. 3-474 .
- ↑ EC Taylor, Jr., AJ Crovetti: Pyridine-1-oxides. I. Synthesis of some nicotinic acid derivatives . In: J. Org. Chem. Band 19 , no. 10 , 1954, pp. 1633-1640 , doi : 10.1021 / jo1375a012 .
- ^ DH Bremner, KR Sturrock, G. Wishart, SR Mitchell, SM Nicoll, G. Jones: A comparison of methods for N-oxidation of some 3-substituted pyridines . In: Synth. Commun. tape 27 , no. 9 , 1997, pp. 1535-1542 , doi : 10.1080 / 00397919708006090 .
- ↑ R. Balicki, J. Golinski: A simple and efficient method for the preparation of N-heteroaromatic N-oxides . In: Synth. Commun. tape 30 , no. 8 , 2000, pp. 1529-1534 , doi : 10.1080 / 00397910008087182 .
- ↑ Patent DE80209 : Process for the production of 2-chloronicotinic acid. Registered November 25, 1969 , published March 5, 1971 , inventor: E. Kretzschmar, H.-J. Heidrich, G. Dietz, S. Henker.