2.2. Epoxidation of TOFA with Ion Exchange Resin Amberlite IR-120 H

The epoxidation of TOFA was carried out in a four-necked round bottom flask. A thermocouple, mechanical stirrer, dropping funnel and a reflux condenser were attached to the necks of the flask. The epoxidation of TOFA was achieved by in-situ generated peroxyacetic acid, which forms from acetic acid and hydrogen peroxide in the presence of an acidic catalyst. During the epoxidation, the molar ratio of TOFA (double bonds-155 g I₂/100 g) to H₂O₂ and AcOH was 1.0:1.5:0.5. At first, the calculated amount of TOFA (700.0 g), acetic acid (128.5 g) and ion exchange resin Amberlite IR-120 H (140.0 g, 20 wt.% of TOFA weight), as the catalyst, was added to the flask. The flask was immersed in a thermostatic water bath (preheated to 40 °C). The speed of the mechanical stirrer was set to 600 rpm, and the mixture was started to stir. A hydrogen peroxide/water (35%/65%) solution (638.5 g) was poured into a dropping funnel. When the content of the flask reached 40 °C, hydrogen peroxide solution was added dropwise to the round bottom flask in a time interval of 30 min. Meanwhile, the temperature of the reaction medium was slowly increased to 60 °C. After the complete addition of hydrogen peroxide, the reaction medium was continued to stir for 6 h at 60 °C and 600 rpm [18]. Afterwards, the reaction mixture was poured into a separating funnel and washed four times with warm (T = 60 °C) distilled water. The product was dried using a rotatory vacuum evaporator to remove water residues. As a result, ETOFA were obtained exhibiting the acid value of 144 mg KOH/g, oxirane content of 2.30 mmol/g and iodine value of 27.0 g I₂/100 g and characterised by pomegranate red colour. An acronym ETOFA_IR is used for the ETOFA synthesised via TOFA epoxidation with ion exchange resin Amberlite IR-120 H.