In this study, potential fungicides were prepared following the principles of green chemistry. The compounds were synthesized in deep eutectic solvents as an alternative medium and compared with syntheses in traditional solvents such as ethanol. The efficiency of the reaction was improved by ultrasonic synthesis in both eutectic solvents and ethanol, resulting in higher yields while reducing reaction energy and time. For the first time, deep eutectic solvents (DES) were used for quaternisation reactions, with choline chloride as a hydrogen bond acceptor and urea, glycerol, malic acid, malonic acid, and levulinic acid as donors. DES, composed of biodegradable, non-toxic, and renewable components, represented a greener alternative to conventional solvents. However, reactions in DES by the conventional method generally resulted in lower yields, probably due to solubility and viscosity limitations inherent in the eutectic medium. The combination of ultrasound and deep eutectic solvents proved to be a good alternative to organic solvents for the quaternisation reaction, as higher yields were achieved in a shorter time compared to conventional methods. The antifungal activity of all 18 synthesized compounds was tested. The compounds exhibited significant antifungal activity against all four pathogens, with varying levels of mycelial growth inhibition. B. cinerea was the most sensitive species (up to 70.7% inhibition), while F. culmorum was the least sensitive (≤32%).
Bušić et al. (Thu,) studied this question.