Simple and facile synthesis of aryl benzoates from stabilized arenediazonium tetrafluoroborate using a recyclable polymer-supported benzoate ion

Abstract

Aryl benzoates are important intermediates with a variety range of applications in organic and bioorganic chemistry. In this article, cross-linked poly (4-vinylpyridine) supported benzoate ion, [P4-VP]PhCO2, is easily prepared and used in an efficient, and simple method for, synthesis of aryl benzoates from aryl amines. In this procedure diazotization of aromatic amine is occurred, by using sodium nitrite in the presence of concentrated H2SO4 at low temperature (0–5 °C). Then the in situ generated aryl diazonium salts, are stabilized by addition of a cold aqueous solution of NaBF4 and dediazoniation is followed by using cross-linked poly (4-vinylpyridine) supported benzoate ion, [P4-VP]PhCO2, in water at room temperature. After addition the [P4-VP]PhCO2, nitrogen gas is removed and the corresponding aryl benzoate product is obtained (Sandmeyer type reaction). Various aromatic amines, with electron-withdrawing groups as well as electron-donating groups, were transformed into aryl benzoates in good yields. The aryl benzoate products were characterized by Fourier transform infrared (FT-IR), and some of them were also characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, and the physical properties were compared to the literature values of known compounds. The advantages of the present method over conventional classical methods are; mild reaction conditions, safe handling, rapid, and very simple work-up. The spent polymeric reagents can also be regenerated and reused for several times without significant loss of their activity.