02717nas a2200301 4500008004100000022001400041245010700055210006900162260007300231300001200304490000800316520171400324653001202038653001802050653002302068653001002091653000702101653001302108653002002121653001802141653002302159100001802182700001602200700002802216700001802244700003002262856012302292 2005 eng d a1381-116900aInsight into the mechanism of selective mono-N-methylation of aniline on Cu1-xZnxFe2O4: a DRIFTS study0 aInsight into the mechanism of selective monoNmethylation of anil aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a169-1800 v2313 a

Mechanism of selective mono-N-methylation of aniline with methanol on Cu1-xZn2FeO4 catalysts was investigated in detail. The interaction of reactants (aniline. methanol and methanol: aniline) and possible products (N-methylaniline (NMA), N,N-dimethylaniline (DMA) and o-toluidine (OT)) on catalysts surface was studied by temperature-dependent in situ FTIR spectroscopy. Methanol adsorbs dissociatively over catalysts surface at 373 K as methoxy species and is oxidized to formate species at high temperature through dioxymethylene and/or formaldehyde as a surface intermediate species. On the other hand, adsorption of aniline:methanol mixtures shows that methanol oxidation was completely hindered in the presence of aniline. Aniline adsorbs on the Lewis acid sites at <= 373 K with phenyl ring oriented in a perpendicular manner to the catalyst surfaced however, N-H bond scission occurs above 373 K. A comparison of adsorbed NMA and methanol: am line (3:1) mixture on Cu0.5Zn0.5Fe2O4 shows NMA forms from the reaction mixture at 473 K. However, maximum activity at 573 K in catalytic reaction studies suggests that desorption limits the methylation kinetics. FTIR study displays stable aniline and methyl species on ZnFe2O4 even at 573 K; however. no methyl species is detected on Cr0.95Zn0.05Fe2O4 at 473 K due to methanol reforming reaction and that limits the overall reaction and hence low catalytic activity. It is proposed that methanol is protonated on catalysts surface by the labile H+ due to N-H bond scission. Co-adsorption of acidity probes with aniline and methanol indicates that aniline methylation takes place at single acid-base site. (c) 2005 Elsevier B.V. All rights reserved.

10aAniline10aCu1-xZnxFe2O410adesorption limited10aDRIFT10aIR10aMethanol10aN-methylaniline10aN-methylation10areaction mechanism1 aVijayaraj, M.1 aMurugan, B.1 aUmbarkar, Shubhangi, B.1 aHegde, S., G.1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/insight-mechanism-selective-mono-n-methylation-aniline-cu1-xznxfe2o4-drifts-study-002227nas a2200265 4500008004100000022001400041245014400055210006900199260009500268300001000363490000800373520126800381653001201649653001201661653002001673653001801693653001101711653001501722653002501737653000801762653000801770100002401778700003001802856012901832 2006 eng d a0021-951700aOn the ``Active spacer and stabilizer'' role of Zn in Cu1-xZnxFe2O4 in the selective mono-N-methylation of aniline: XPS and catalysis study0 aActive spacer and stabilizer role of Zn in Cu1xZnxFe2O4 in the s a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcJUL a83-950 v2413 a

A systematic catalytic methylation study on ferrospinel materials led to the selective production of N-methylaniline (NMA) with Cu1-xZnxFe2O4. Aniline methylation was carried out on Cu1-xZnxFe2O4 with a feed composition of CH3OH:PhNH2:H2O = 3:1:1 at 513-633 K. NMA was formed selectively on all of the catalyst compositions, with trace amounts of secondary products under most of the conditions. Cu0.5Zn0.5Fe2O4 composition showed high catalytic activity and stability up to 100 h. Although the Cu2+ was responsible for methylation activity, Zn2+ enhanced the overall stability of the catalyst system. XPS investigations revealed that the degree of Cu2+ reduction decreased dramatically from x = 0.05/0.25 to 0.5/0.75 on spent catalysts. TPR studies indicated that the reducibility of Cu2+ decreased from fully reducible at 523 K with Cu-rich compositions to partially reducible at 573 K on x = 0.5. Stable activity observed on Cu0.5Zn0.5Fe2O4 can be attributed to the highly heterogeneous distribution of metal ions. This heterogeneous distribution indicates an important role of zinc, likely as an ``active spacer cum stabilizee' that hinders the reduction of active Cu2+ and contributes to prolonged activity. (c) 2006 Elsevier Inc. All rights reserved.

10aAniline10aFerrite10aN-methylaniline10aN-methylation10aspacer10astabilizer10asurface distribution10aTPR10aXPS1 aVijayaraj, Munusamy1 aGopinath, Chinnakonda, S. uhttps://library.ncl.res.in/content/active-spacer-and-stabilizer-role-zn-cu1-xznxfe2o4-selective-mono-n-methylation-aniline-102410nas 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

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 > o-toluidine > 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.

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-xznxfe2o401737nas a2200217 4500008004100000022001400041245009700055210006900152260007300221300001200294490000700306520095500313653001501268653001201283653001901295653002401314653002001338100001801358700002201376856012101398 2009 eng d a0169-131700aSelective N-alkylation of aniline with methanol over a heteropolyacid on montmorillonite K100 aSelective Nalkylation of aniline with methanol over a heteropoly aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY a255-2580 v443 a

N-methylaniline is an industrially important product in the manufacture of paper, textile dyes, drugs, perfumes and explosives. The vapour phase alkylation of aniline with methanol forming N-methylaniline is advantageous over liquid phase alkylation. In present study, vapour phase methylation of aniline over dodecatungestophosphoric acid supported on K10 montmorillonite was systematically studied and optimization of process parameters was carried out. The 20% m/m DTPA/K10 was found to be optimum with 79% aniline conversion and 99% N-methylaniline selectivity. The reaction required milder operating conditions than reported for commercial catalysts. We also studied the feasibility of 20% m/m DTPA/K10 as a catalyst for the alkylation of aniline with other alcohols like ethanol, n-propanol, iso-propanol and n-butanol. The activity of 20% m/m DTPA/K10 decreased with increasing carbon number. (C) 2009 Elsevier B.V. All rights reserved.

10aAlkylation10aAniline10aHeteropolyacid10amontmorillonite K1010aN-methylaniline1 aNehate, Manoj1 aBokade, Vijay, V. uhttps://library.ncl.res.in/content/selective-n-alkylation-aniline-methanol-over-heteropolyacid-montmorillonite-k10-001711nas a2200253 4500008004100000022001400041245009700055210006900152260005700221300001200278490000800290520085800298653001201156653001501168653001301183653002001196653001101216100002201227700001801249700001801267700002701285700002201312856012301334 2009 eng d a1011-372X00aSynthesis of N-methylaniline by aniline alkylation with methanol over Sn-MFI molecular sieve0 aSynthesis of Nmethylaniline by aniline alkylation with methanol  a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcNOV a175-1840 v1333 a

Sn-MFI molecular sieves (Tin silicalite-1) with SiO(2)/SnO(2) molar ratio of 50-150 were synthesized and characterized. Elemental analysis, XRD and DRUV-vis confirmed that prepared samples were of MFI zeolite structure and Sn was incorporated in MFI framework. Vapor phase methylation of aniline over Sn-MFI was systematically studied and optimizations of process parameters were carried out. Sn-MFI (SiO(2)/SnO(2) = 50) was found to be optimum catalyst with 55% aniline conversion and 60% N-methylaniline selectivity. At lower space velocity (higher contact time) of 1 h(-1), aniline conversion was found to be increased to 71% with reduction in N-methylaniline selectivity to 39% and increased in N,N-dimethylaniline selectivity to 58%. The reaction follows first order kinetics with respect to aniline having activation energy of 7.3 kcal/mol.

10aAniline10aLewis acid10aMethanol10aN-methylaniline10aSn-MFI1 aNiphadkar, P., S.1 aJoshi, P., N.1 aGurav, H., R.1 aDeshpande, Suvarna, S.1 aBokade, Vijay, V. uhttps://library.ncl.res.in/content/synthesis-n-methylaniline-aniline-alkylation-methanol-over-sn-mfi-molecular-sieve-002289nas a2200241 4500008004100000022001400041245013400055210006900189260007300258300001200331490000800343520139200351653001401743653001201757653002801769653001301797653002001810100002201830700001801852700002701870700002201897856012801919 2011 eng d a0926-860X00aInfluence of Al3+ insertion in the stannosilicate MFI framework on the catalytic performance in vapor phase aniline N-methylation0 aInfluence of Al3 insertion in the stannosilicate MFI framework o aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL a182-1880 v4013 a

Silica-based Sn-MFI, Al-MFI and Al-Sn-MFI molecular sieves were synthesized by hydrothermal crystallization of gels having molar compositions SiO2:xSnO(2):yAl(2)O(3):0.23 (TPA)(2)O:35H(2)O, where x ranges from 1/0 to 1/200 and y from 1/0 to 1/400. Keeping molar Si/(Al + Sn) = 50, the amount of tin and aluminum in hydrogel was varied (Sn:Al molar ratios = 1:0, 1:0.33, 1:1, 1:3, 0:1) to investigate the synergy between Lewis and Bronsted acid sites in acid catalyzed aniline N-methylation reaction. Catalyst characterization was done by Powder X-ray diffraction, DRUV-vis spectroscopy, temperature programmed ammonia desorption (TPAD) and FTIR spectroscopy. An increase in the Al3+ insertion in Sn-MFI framework resulted in the increase in the stronger acid sites. Al-Sn-MFI showed higher aniline conversion than their monometallic counterparts. A sample having B/L ratio in between 0.67 and 0.91 was found to be optimum for maximizing the NMA yield, indicating the existence synergistic properties of Al-Sn-MFI. Upon process parameter optimization, the optimum sample M50 [Si/Al = 50.2, Si/Sn = 93.8, Si/(Al + Sn) = 43.2] showed the maximum aniline conversion (67%) and NMA selectivity (81%) at reaction temperature = 220 degrees C, weight hourly space velocity (WHSV) = 3 h(-1), molar ratio (aniline to methanol) = 1:8 and TOS = 4 h. (C) 2011 Elsevier B.V. All rights reserved.

10aAl-Sn-MFI10aAniline10aBronsted and Lewis acid10aMethanol10aN-methylaniline1 aNiphadkar, P., S.1 aJoshi, P., N.1 aDeshpande, Suvarna, S.1 aBokade, Vijay, V. uhttps://library.ncl.res.in/content/influence-al3-insertion-stannosilicate-mfi-framework-catalytic-performance-vapor-phase-0