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Studies on Synthesizing P-Tert-Butyl Benzoic Acid(II)

Nitric acid oxidation method

Preparation of crude PTBBA: Adding 26mL (0.2mol,29.6g) p-tert-butyl toluene (PTBT), 26mL 68%(0.4mol,37g) Nitric acid, and then 215mL water into the 500 mL autoclave. Closing the lid and starting the stirrer. The temperature is heated to 180℃ and the traction time is kept to be 8 h. After water cooling off, the cover was removed. Majority of the solids deposited at the autoclave bottom, and some was attaching to the cooling pipes. Collecting the solid, filtrating and drying, the weight is 34.5 g and productivity is 95.5%.
Purifying P-tert-butyl benzoic acid: Weighting 10g Sodium Hydroxide and making it into 10% solution with 90 mL water. Adding above solid into the solution. After completely dissolved, filtrating it. Adjusting the filtrate’s ph value to be around 3 with Hydrochloric acid. Then there is large quantity of crystalline happening. Stewing and filtrating, 33.4g material will be yielded and the productivity is 98.2%.
Even if the productivity is high with Nitric acid oxidation method to prepare P-tert-butyl benzoic acid, the causticity of nitric acid to the devices is great. During the reaction, the side products, such as nitrogen oxides, have great effect on the environment.
Acetate solvent catalytic oxidation method:
This method takes p-tert-butyl toluene (PTBT) as raw material, Cobalt Acetate as the catalyst and acetate acid as solvent. 250 mL stainless steel autoclave is the main reaction device, with mechanical stirrer. The air inlet and products outlet are at the bottom of the autoclave. The reaction is free redical chain reaction. The theory is below:

High temperature make p-tert-butyl toluene (PTBT) oxidized to yield P-tert-butyl benzoic acid with suitable catalyst. The productivity is high, but there is too many side products and the reaction takes too long time.