Sodium Bromide → 4-(Pyridin-4-yl)benzoic acid

Participants

Reaction Conditions

Reaction Steps

177.2 g (0.75 mol) of 4-p-tolyl-N-pivaloyldihydropyridine, 1511.2 g of acetic acid, 3.74 g (15.0 mmol) of cobalt(II) acetate tetrahydrate, 3.68 g (15.0 mmol) of manganese(II) acetate tetrahydrate and 3.09 g (30.0 mmol) of sodium bromide are placed in a 3.5 l autoclave. The autoclave is made inert using nitrogen and is heated to 160-165° C. When this temperature has been reached, about 450 l/h of air are introduced and an internal pressure of 16-18 bar is maintained by means of a pressure maintenance device. Air is introduced for about 30-40 minutes, the autoclave is then once again made inert by injection of nitrogen and the mixture is cooled. The greenish solution (becomes orange-red on cooling) is taken from the autoclave and evaporated to a weight of 370 g on a rotary evaporator. The thick suspension is filtered on a suction filter and the crystals are washed 3 times with 50 g each time of 75% strength by weight acetic acid. The crude product obtained in this way is taken up in 75 ml of 0.4% strength by weight sodium bicarbonate solution, stirred for 30 minutes at about 50° C. and filtered off. Drying leaves 4-(4′-carboxyphenyl)pyridine in a yield of 90%. HPLC purity: >98% (a/a).

Provenance & Evidence