Phthalic acids from corresp. aldehydes by liquid phase oxidation - with oxygen and catalyst contg. manganese cpd. and bromine cpd.

摘要

Phthalic acid, isophthalic acid or terephthalic acid are prepd. by oxidising the corresp. tolualdehydes with an oxygen contg. gas in the liquid phase contg. a lower aliphatic monocarboxylic acid and =1 heavy metal salts comprising =1 Mn salt and =1 bromine cpd. as catalyst, the quantity of Mn in the reaction system being is not 40 ppm (based on the total weight of solvent and water). The process is used partic. to prepare terephthalic acid, which is an inter. for polyesters and plasticizers. Previously it has been found that when the acid is prepd. from the aldehyde, the quality of prod. is inferior to that obtd. from xylene oxidn. The above process overcomes this difficulty and gives a very white prod.