INVESTIGATION OF THE CATALYTIC EFFECT OF POTASSIUM TRET-BUTOXIDE IN THE AMIDATION REACTIONS OF RAPESEED OIL ACYLGLYCERIDES

Abstract

Background. Alkalis and metal alkoxides are used as catalysts for the amidation of vegetable oils. However, the use of known catalysts does not always allow to soften the conditions of the processes to the required level. The use of potassium tret-butoxide as a catalyst for these reactions can serve as a solution to the problem.Objective. Verification of the use of potassium tert-butoxide as a catalyst for the amidation reaction of vegetable oil acylglycerides.Methods. To achieve this goal, a series of syntheses of the amidation of rapeseed oil with ethylenediamine, diethanolamine and dibutylamine in the presence of potassium tert-butylate was carried out. The dependences of the yields of the target product on the catalyst content, temperature and reaction time were studied.Results. It is shown that with the introduction of potassium t-butoxide in the reaction mixture in amounts from 0.1 to 1 mole percent, the reaction rate increases dramatically. A further increase in the amount of catalyst even to the molar ratio of 1/1 in the same conditions increases the yields by only 20% and is not advisable. The optimal molar ratio of rapeseed oil/t-butoxide was 1/0.01. It was found that the optimal temperature for carrying out the amidation in the presence of potassium tert-butoxide is in the range of 60–90 °C, depending on the structure of the amine used. It was revealed that the reaction also takes place at room temperature, although the yields of the target products are too low. However, the use of potassium tert-butoxide allows syntheses to be carried out under conditions in which hydroxides and other metal alkoxides are not effective. It is established that the optimal time for the amidation of rapeseed oil at the revealed temperature is on average 6–8 hours, depending on the structure of the amine. With reduced in temperature, in order to obtain a satisfactory yield, the time for synthesis should be increased.Conclusions. Studies have shown that potassium tert-butoxide exhibits a significantly greater catalytic activity in the amidation reactions of oils than other alkaline catalysts. This significantly mitigates the conditions of amidation and reduces the energy costs of the process. In addition, the data obtained make it possible to further vary the temperature and time of synthesis of vegetable oil amides, depending on the tasks.