Ultrasound improves the synthesis of 5-hydroxymethyl-2-mercapto-1-benzylimidazole as a base compound of some pharmaceutical products

Application of ultrasound in synthesis appears to be a promising alternative for high-value chemicals and pharmaceuticals. This work describes the results of investigations carried out towards the synthesis of 5-hydroxymethyl-2-mercapto-1-benzylimidazole (HMMBI) in the presence of ultrasound (sono-synthetic) and in the absence of ultrasound (control method). Instead of mixing for long time in control method, the mixture was sonicated indirectly with 500 kHz and directly with 20 kHz apparatus. In some experiments the yield of the reaction was optimized by suitable manipulation of conditions such as temperature, vapor pressure of the solvent, ultrasonic intensity, and contact time. In control method, the yield of the reaction was increased by increasing the temperature but in sono-synthetic method, the thermal dependency was different in the range of temperature studied (7–25 °C). Kinetic results at 7 °C indicate that the yield of the reaction was reached to 90% after half an hour sonication but in control method it was reached to 70% after 72 h under the same conditions. Therefore, it is possible to reach a high yield of product under proper conditions of sonication.

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