“…7,10,13,14 The inserted functional groups, particularly carboxyls, are also basis for subsequent functionalization, such as amidation, alkylation, esterification and thiolation. 6,7,15,16 SO 4 , which are based on a single step treatment or a two-step sequence. The most common processes use ultrasonic bath, [17][18][19][20] reflux at high temperatures 9,12,13,[20][21][22][23][24][25][26] (occasionally under magnetic stirring) 10,27,28 or ultrasonic bath followed by reflux.…”