Preparation of an improved sulfonated carbon-based solid acid as a novel, efficient, and reusable catalyst for chemoselective synthesis of 2-oxazolines and bis-oxazolines

A highly sulfonated carbon as an efficient, recyclable, nontoxic, and green solid acid catalyst was readily synthesized by simultaneous sulfonation, dehydration, and carbonization of sucrose in sulfuric acid and was characterized by FT-IR, TG-DTG, XRD, and CHNS analysis, neutralization potentiometric titration, and SEM techniques. This new catalyst was used for preparation of 2-oxazolines and bis-oxazolines by reaction of beta-aminoethanol with nitriles under reflux conditions. Sonication of this system enhanced the catalytic activity of the carbon-based solid acid and led to higher product yields and shorter reaction times. Another advantage of the system under ultrasonic irradiation is the ability to carry out large-scale reactions. In two cases, the catalyst was reused several times without loss of its activity.