In this paper we compare two different reactions, aimed at the synthesis of 1,2-cyclohexanediol.Specifically: (a) the direct epoxidation and hydrolysis (dihydroxylation) of cyclohexene to trans-1,2-cyclohexanediol, with an aqueous solution of hydrogen peroxide, and (b) the hydrogenation of catecholto a mixture of cis and trans-1,2-cyclohexanediol, in an attempt to establish green protocols for the syn-thesis of diols. Both reactions, the dihydroxylation of cyclohexene and the hydrogenation of catechol,were carried out without organic solvents. In the former case, an unprecedented 97.4% yield to the glycolwas obtained, by selecting proper reaction conditions and using a tungstic acid/phosphoric acid catalyst,in a biphasic system with a phase-transfer agent. In the second approach, a heterogeneous alumina-supported Ru(OH)xcatalyst was used, and a 90% yield to the glycol was obtained. A comparison of thetwo processes allowed to show the lower environmental impact of the catechol hydrogenation route.
Two alternative routes for 1,2-cyclohexanediol synthesis by means of green processes: Cyclohexene dihydroxylation and catechol hydrogenation
RAABOVÁ, KATERINA;ROZHKO, ELENA;CALDARELLI, AURORA;RIGHI, PAOLO;CAVANI, FABRIZIO;
2013
Abstract
In this paper we compare two different reactions, aimed at the synthesis of 1,2-cyclohexanediol.Specifically: (a) the direct epoxidation and hydrolysis (dihydroxylation) of cyclohexene to trans-1,2-cyclohexanediol, with an aqueous solution of hydrogen peroxide, and (b) the hydrogenation of catecholto a mixture of cis and trans-1,2-cyclohexanediol, in an attempt to establish green protocols for the syn-thesis of diols. Both reactions, the dihydroxylation of cyclohexene and the hydrogenation of catechol,were carried out without organic solvents. In the former case, an unprecedented 97.4% yield to the glycolwas obtained, by selecting proper reaction conditions and using a tungstic acid/phosphoric acid catalyst,in a biphasic system with a phase-transfer agent. In the second approach, a heterogeneous alumina-supported Ru(OH)xcatalyst was used, and a 90% yield to the glycol was obtained. A comparison of thetwo processes allowed to show the lower environmental impact of the catechol hydrogenation route.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.