02463nas a2200253   4500008004100000022001400041245009700055210006900152260009500221300001200316490000800328520157000336653002201906653002101928653001001949653001801959653000801977653001801985653002102003653000802024100002402032700003002056856012302086       2006                        eng d  a0021-951700aSelective production of methoxyphenols from dihydroxybenzenes on alkali metal ion-loaded MgO0 aSelective production of methoxyphenols from dihydroxybenzenes on  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcOCT  a376-3880 v2433 a<p>Selective O-methylation of dihydroxybenzenes (DHBs; catechol, resorcinol, and hydroquinone) to methoxyphenols (MPs) was carried out with dimethylcarbonate on MgO and alkali metal ion (Li, K, and Cs)-loaded MgO between 523 and 603 K. Catalytic activity and product selectivity varied with respect to DHB substrates. Selectivity for O-methylated products increased with increasing basicity of alkali ions; however, K-MgO showed high and stable activity toward MPs. Selectivity for MPs obtained from three substrates increased in the following order: catechol &lt; resorcinol &lt; hydroquinone. The mode of interaction of substrates on the catalysts surface influenced reactivity and product selectivity. It is likely that the low reaction temperatures used (&lt; 603 K) kinetically control and favor high MP selectivity from DHBs. Calcined and spent catalysts were characterized by XRD, surface area, SEM, thermal analysis, NMR, and XPS. XRD analysis revealed the formation of alkali oxide phases on alkali-loaded MgO. Crystallite size and surface area of the catalysts decreased after methylation reactions, except on K-MgO. TGA showed 4060 wt% coke deposition on spent catalysts. TGA in N-2 followed by air and C-13 CP-MAS NMR measurements indicated the nature of deposited carbon to be molecular species, graphite, MgCO3 and polyaromatics. XPS revealed the nature and availability of active sites on the spent catalysts, as well as the same changes with reaction conditions and correlated with catalytic activity. (c) 2006 Elsevier Inc. All rights reserved.</p>10aalkali-loaded MgO10adihydroxybenzene10aK-MgO10amethoxyphenol10aMgO10aO-methylation10athermal analysis10aXPS1 aVijayaraj, Munusamy1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/selective-production-methoxyphenols-dihydroxybenzenes-alkali-metal-ion-loaded-mgo-002242nas a2200217   4500008004100000022001400041245012000055210006900175260000800244300001400252490000800266520146600274653002001740653001701760653001801777653004101795100002301836700002101859700002101880856012301901       2022                        eng d  a1011-372X00aReusable and efficient polystyrene immobilized ionic liquid catalyst for batch and flow methylation of hydroquinone0 aReusable and efficient polystyrene immobilized ionic liquid cata  cNOV  a3304-33160 v1523 a<p>
	An environmentally benign process for synthesizing 4-methoxyphenol through methylation of hydroquinone using polystyrene immobilized Bronsted acidic ionic liquid is presented. The catalyst has been characterized by several techniques, such as solid-state NMR, FTIR, and XRD. The morphological properties were analyzed through SEM and TEM analysis. The elemental analysis was performed using EDS and XPS techniques. The catalyst was thermally stable up to 603 K, which was confirmed by TGA. The chemical interaction between ionic liquid and polystyrene was confirmed by measuring the glass transition temperature of pure polystyrene and catalyst. The BET analysis was performed to estimate the catalyst's surface area, pore size, and pore volume. The recyclability of the proposed new catalyst was established up to five recycle runs in the batch mode. In addition, continuous flow experiments were conducted to test the catalytic activity in terms of catalyst life span and showed excellent stability up to 20 h. The rapid separation, long-term stability, and efficient recycling of synthesized polymeric catalysts make an excellent alternative to the commonly used homogeneous catalysts for selective O-methylation of hydroquinone reaction. The newly developed continuous process for synthesizing 4-methoxyphenol with 100% selectivity suggests good opportunities to reduce energy consumption, which designates a cost-effective process. [GRAPHICS] .</p>
10a4-Methoxyphenol10aHydroquinone10aO-methylation10aPolystyrene immobilized ionic liquid1 aBhongale, Priyanka1 aJoshi, Sunil, S.1 aMali, Nilesh, A.  uhttps://library.ncl.res.in/content/reusable-and-efficient-polystyrene-immobilized-ionic-liquid-catalyst-batch-and-flow