New process for the synthesis of the 2-propyl pentane nitrile under ultrasonic irradiation
Résumé
The synthesis of 2-propyl pentane nitrile (DPAN) is a key step in the synthesis of a drug (valproic acid). The usual process is based on sodium-amide-mediated alkylation of valeronitrile. We describe a possible new process, which makes use of metallic sodium. The reaction has been carried out with ultrasound and the results compared with those obtained under “silent” conditions with different stirring systems. Under sonication, a several percentage improvement of the chemical yield and selectivity, and a low rate increase are observed. The optimum temperature (about 25 °C) and sodium particle size (about 2 mm) have been determined.