Nitric Acid → 3-Methyl-5-isoxazolecarboxylic acid

A mixture of acetonylacetone (10 g, 88 mmol) and nitric acid (sp. gr. 1.42)/water (2:3) (50 ml) was cautiously brought to reflux under a stream of nitrogen and boiled for 1 h. The solution was cooled to room temperature and aged overnight. The resultant solid was collected by filtration, washed with chilled water (2×7 ml) and hexane, and dried in vacuo to give the title-acid (4.4 g, 40%), 1H NMR (CDCl3) δ 2.50 (3H, d, J=0.8 Hz, Me), 6.41 (1H, d, J=0.8 Hz, Ar—H).

1. temperatureto reflux under a stream of nitrogen
2. filtrationThe resultant solid was collected by filtration
3. washwashed with chilled water (2×7 ml) and hexane
4. customdried in vacuo
5. customto give the title-acid (4.4 g, 40%), 1H NMR (CDCl3) δ 2.50 (3H, d, J=0.8 Hz, Me), 6.41 (1H, d, J=0.8 Hz, Ar—H)

ORD record

ord-c1c56a0ae6b344cb83aae5085a3596d7

Source dataset

uspto-grants-2003_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06534505B2