Hydrochloric Acid → 8-methoxy-1-oxo-1H-2-benzothiopyran-3-carboxylic acid

Reaktionsgleichung

[C:1]([C:4]1[C:17]([O:18][CH3:19])=[CH:16][CH:15]=[CH:14][C:5]=1[CH:6]=[C:7]1[S:11]C(=S)N[C:8]1=[O:13])([OH:3])=O.[OH-:20].[Na+].Cl>>[CH3:19][O:18][C:17]1[C:4]2[C:1](=[O:3])[S:11][C:7]([C:8]([OH:20])=[O:13])=[CH:6][C:5]=2[CH:14]=[CH:15][CH:16]=1

Komponenten

Edukt 3

HCID 313Hydrochloric Acid

HCID 14798Sodium Hydroxide

HCID 543067415-(2-Carboxy-3-methoxybenzylidene)rhodanine

Produkt 1

HCID 214407508-methoxy-1-oxo-1H-2-benzothiopyran-3-carboxylic acid

Versuchsvorschrift

A solution of the benzylidenerhodanine of Example 10 in 46 ml. of 15% NaOH is refluxed for 0.75 hour, cooled, and poured into dilute HCl. The resulting tan precipitate is collected and air-dried. Two recrystallizations from methanol (charcoal) give 8-methoxy-1-oxo-1H-2-benzothiopyran-3-carboxylic acid as a pale yellow solid, m.p. 275° (dec.).