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-002410nas a2200217   4500008004100000022001400041245007200055210006900127260007300196300001000269490000800279520165000287653002301937653002001960653001801980653002801998653001102026100002402037700003002061856010102091       2007                        eng d  a0926-860X00aSelective mono-N-methylation of aniline substrates on Cu1-xZnxFe2O40 aSelective monoNmethylation of aniline substrates on Cu1xZnxFe2O4  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR  a64-680 v3203 a<p>Selective mono-N-methylation of substituted anilines (o-, m- and p-toluidines, 2,6-xylidine, p-anisidine and p-aminoacetophenone) was carried out with methanol as methylating agent under vapor phase reaction conditions on Cu1-xZnxFe2O4 systems. The catalytic reactions with each aniline substrate were carried out at optimum reaction conditions (MeOH:anilines:water = 3: 1: 1, space velocity = 3.58 h(-1)) between 543 and 603 K. The presence of a ring-directing group did not have any significant influence on the N-methylaniline(s) selectivity, which remains very high; the same initial conversion/yield was observed for at least 11 h. Electronic effects due to different groups in the above aniline substrates influence the reactivity of the substrates in terms of conversion and yield. Toluidine reactivity varies with respect to the position (ortho, meta and para) of the methyl group on the phenyl ring. Para-substituted anilines (p-toluidine and p-anisidine) exhibit comparable catalytic activity, while p-aminoacetophenone shows higher conversion. The perpendicular orientation of toluidine substrates on catalyst surfaces influences the conversion and N-methyltoluidine yield. Increased crowding at ortho-position and hence steric hindrance (aniline &gt; o-toluidine &gt; 2,6-xylidine) restrict the substrates interaction with the catalyst surface, and 2,6-xylidine shows no reactivity. The best catalytic activity observed with Cu0.5Zn0.5Fe2O4 was due to a heterogeneous distribution of metal ions on the surface with Zn serving as active spacer group as well as methyl species source. (c) 2007 Elsevier B.V. All rights reserved.</p>10amono-N-methylation10aN-methylaniline10aN-methylation10aselective N-methvlation10aspinel1 aVijayaraj, Munusamy1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/selective-mono-n-methylation-aniline-substrates-cu1-xznxfe2o4