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Paracetamol (acetaminophen) is one of the most frequently used analgesic and antipyretic drugs. This work deals with ultrasound assisted synthesis (UAS) of paracetamol from hydroquinone using ammonium acetate as an amidating agent. The optimization of various reaction and ultrasound parameters was performed to minimize the energy and time requirement. UAS of paracetamol was achieved at a lower temperature (60 °C) and the time (150 min) without formation of salt as a byproduct, making reaction green and inherently safer. On the other hand, the conventional process requires high reaction temperature (220 °C) and time (15 h). The quantification of the product was done by using high performance liquid chromatography (HPLC). Optimization of parameters revealed that the percent yield of 57.72% can be obtained in 150 min by performing the reaction in the ultrasound bath at 22 kHz frequency, 60 °C temperature, hydroquinone to ammonium acetate and acetic acid in a molar ratio of 1:6:5, 125 W power, 50% duty cycle and agitation speed of 300 RPM. Hence, ultrasound assisted synthesis can be considered as a process intensification tool for the synthesis of paracetamol and possibly other pharmaceutical compounds.

The extraction of rice bran proteins from rice mill industry waste was performed using alkali and NaCl combined with alkali (at pH of 9) as the extracting medium. Initially, residual oil was extracted from the crude rice bran followed by removal of solvent used for oil extraction. The optimum processing conditions for the alkaline extraction were established as pH of 9, solute to solvent ratio as 1:50, agitation speed as 400 rpm and recovery time of 2 h. Using these optimized conditions, the yield obtained was around 76%, but some undesired phenolic compounds were also extracted along with proteins giving bitter taste and dark color to the recovered protein. To eliminate this issue, extraction was also performed using NaCl solution in combination with alkali and the optimum parameters for this combined approach were established as NaCl concentration of 0.5 M, solute to solvent ratio as 1:50, recovery time of 2 h and agitation speed of 400 rpm. Under these conditions, 70% recovery of proteins was achieved but most importantly with the desired quality characteristics. PRACTICAL APPLICATIONSCurrent industrial processes use harsh conditions to extract oil and recovery of hexane after oil extraction, which denatures the proteins in rice bran, due to high temperatures used in processing. Also, there are some protein extraction processes, in which extraction is performed with higher alkaline pH giving bitterness and dark color to the final protein concentrate. A modified process was developed using low temperature (608C) for oil extraction and hexane recovery with application of vacuum (200 mbar). Protein extraction was performed using alkaline extraction at optimum pH of 9 and combined NaCl and alkaline extraction, which helped to eliminate the problem of bitterness and color. The development of process with higher extraction in a lower time and improved protein quality is of great importance from an industrial point of view.

The study was designed to investigate the use of ultrasound-assisted extraction (UAE) of rapamycin (sirolimus) from bacterial strain of Streptomyces rapamycinicus NRRL 5491. To achieve the maximum extraction yield, various parameters were optimized which include S. rapamycinicus (10 g) of biomass in toluene (50 mL), temperature (20°C), acoustic intensity (35.67 W/cm), and duty cycle (40%) for 4 min extraction time with probe tip length of 0.5 cm dipped into extraction solvent from the surface. The maximum extraction yield 60.15 ± 0.01 mg/L was attained under the mentioned optimum parameters. The use of ultrasound for the extraction of rapamycin shows about twofold increase in the yield as compared to the conventional solid-liquid extraction (29.7 ± 0.2 mg/L). The study provides the effective UAE technique to produce potential value-added products.