
TY  - JOUR
A1  - Korsch, BH 
A1  - Riggs, NV 
T1  - Structure and Acid Strength of Opianic Acid and Its N-Methyl Oxime
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1963
VL  - 16
IS  - 4
SP  - 709
EP  - 716
KW  - 
UR  - https://doi.org/10.1071/CH9630709 
N2  - In water, undissociated opianic acid exists as an equilibrium mixture containing c. 30% of lactol form (Ia) in equilibrium with open-chain form (IIa); the carboxyl group is therefore a stronger acid by c. 0.5 pK units than the measured value (pK 3.06 ± 0.03) indicates. Opianic acid N-methyl oxime exists largely as the classical nitrone carboxylic acid (IIIa) in water, and is slightly weaker (pK 2.6-2.7) than opianic acid. Both compounds exist largely as cyclic forms, (Ia) and (IV), respectively, in chloroform. 
ER  -

