Réaction #92953

Équation de réaction

acetic acid anhydride

Et3N

isocinchomeronic acid-N-oxide

→

6-hydroxy nicotinic acid

Rendement 79.1%

Solvants

CCl4

Conditions de réaction

Traitement

1. 1
   Autrerose to 50° C
2. 2
   AutreAfter completion of the reaction the solvents
3. 3
   workup.DISTILLATIONwere distilled off
4. 4
   workup.ADDITIONAbout 100 ml of 20 percent KOH was added drop by drop to the viscous residue
5. 5
   AutreAfter removal of the Et3N
6. 6
   Extractionby extraction
7. 7
   Lavagewashed with water
8. 8
   Autredried under a vacuum

Mode opératoire

20.4 g of acetic acid anhydride (0.2 mole), 20.2 g of Et3N (0.2 mole) and 50 ml of CCl4 were put up in a flask. 18.3 g of isocinchomeronic acid-N-oxide (0.1 mole) was added by portions to this solution. The temperature rose to 50° C. After completion of the reaction the solvents were distilled off. About 100 ml of 20 percent KOH was added drop by drop to the viscous residue and the acetate was saponified over a 15 minute period at 80° C. After removal of the Et3N by extraction, the aqueous solution was acidified with concentrated HCl. The precipitate was sucked off, washed with water and dried under a vacuum. 11.0 g of 6-hydroxy nicotinic acid was obtained, which was pure according to NMR. The crude yield was about 79 percent.

Source