Aktualʹnì Pitannâ Farmacevtičnoï ì Medičnoï Nauki ta Praktiki (May 2020)
The ozonolytic synthesis of acetophenone - a by-product for the production of drugs of calming effect
Abstract
Acetophenone is an important by-product for the manufacture of drugs of calming effect. Known methods of its production don't have the future due to technological complexity, harsh synthesis conditions and low processing coefficients of raw materials. Therefore, the development of low-waste, low-temperature synthesis of acetophenone with ozone is an urgent task. The purpose of the work was to study the kinetic regularities of the reaction of ozone with ethylbenzene in acetic acid and to create the ozonolytic synthesis of acetophenone. Materials and methods. Glacial acetic acid of “Sigma” firm of qualification "Ch. P."; ethylbenzene, acetophenone of “Acros Organics” firm of qualification “Ch. P.”; acetates of metals of qualification “Ch. P.” were applied. The concentration of O3 in the gas phase was determined by a spectrophotometric absorption method in the range of 254–290 nm on spectrophotometer SF-46, which was designed to measure the transmittance of liquid and solid transparent substances in the spectral range from 190 to 1100 nm. Identification of the components of the reaction mass and their quantitative analysis in solution was performed by gas-liquid chromatography. Results. The kinetic regularities of the oxidation of ethylbenzene with ozone in a solution of glacial acetate have been investigated. It is shown that ozone occurs at a temperature of 15 °C, mainly by the aromatic ring. The addition into the catalyst system - manganese (II) acetate has increased the selectivity of oxidation on the side chain from 34.0 to 87.7 %. Acetophenone (76.5 %) and methylphenylcarbinolacetate (11.2 %) are formed as the main products. Conclusions. Ozonation of ethylbenzene in acetic acid was taken place mainly on the aromatic ring, and it was not possible to obtain acetophenone in high yield. The addition of transition metals allowed to be directed the process along the side ring to form 76 % acetophenone.
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