オキシ安息香酸アルカリ塩の溶媒中での熱安定性

石炭酸誘導体のカルボキシル化反応 (第16報)

抄録

The thermal rearrangement of alkali salts of hydroxy benzoic acids in various organic solvents under carbon dioxide pressure was investigated in order to get some information about the effect of solvents on carboxylation of alkali phenoxides with CO₂ in solution.
Potassium salts of p-hydroxybenzoic acid (POB) and salicylic acid (SA) were stable at 180°C and no isomerization from o-isomer to p-isomer and very little decarboxylation were observed. At 240°C, the recovery of the original acids was much less especially with monosalts of POB and SA.
Some solvents were found to affect the stability of the salts. However, the yields of acids and the ratio of p-isomer/o-isomer were not so easily related with the properties of the solvents.
The behavior of sodium salts was found to be quite similar to that with the potassium salts at low temperature.