Hollow, mesoporous, eutectic Zn1−xMgxO nano-spheres as solid acid–base catalysts for the highly regio-selective O-methylation of 1, 2-diphenols. Issue 22 (15th October 2021)

• Record Type: Journal Article
• Authors: Wang, Xuri; Zhang, Jianing; Xie, Guangxin; Yin, Zuyong; Liu, Jie; Ma, Xuebing
• Is Part Of: Catalysis science & technology. Volume 11:Issue 22(2021)
• Page Start: 7454
• Page End: 7466
• Publication Date: 2021-10-15
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/d1cy01236c
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : Hollow, mesoporous and eutectic Zn1− x Mg x O nanospheres promote the highly selective O -methylation of 1, 2-diphenols to afford mono-ethers in complete conversion together with excellent mono-ether selectivities via single-site activation model. Abstract : The highly regio-selective O -methylation of catechol with dimethyl carbonate (DMC), catalyzed by a solid acid–base catalyst, is an environmentally friendly chemical process for industrial production of guaiacol. However, a guaiacol yield below 84% and high reaction temperature above 280 °C limit its industrial application. Here, hollow, mesoporous Zn1− x Mg x O nano-spheres with a eutectic structure, denoted as Zn1− x Mg x O HMNSs ( x = 0.012–0.089), are facilely fabricated via the calcination of Mg 2+ /Zn 2+ ion-adsorbing carbon spheres at 500 °C in air. In the O -methylation of catechol with DMC at 180 °C, Zn1− x Mg x O HMNSs ( x = 0.052) afford guaiacol in 95.5% yield with a complete catechol conversion. Furthermore, 89.0–95.3% mono-ether yields with high 1, 2-diphenol conversions (94.5–100%) are also obtained for the other 1, 2-diphenols bearing –CH3 and –Br groups. Moreover, a plausible mechanism for highly selective O -methylation of catechol with DMC is proposed, in which the single-site activation and double-site activation of phenolic hydroxyls by the basic oxygen of Mg–O afford guaiacol and veratrole, respectively.