02010nas a2200229 4500008004100000022001400041245012500055210006900180260007300249300001200322490000800334520115300342653001601495653002201511653001401533653002201547653002501569100002101594700002301615700001701638856012501655 2009 eng d a0926-860X00aSelective hydroxyalkylation of phenol to bisphenol F over dodecatungstophosphoric acid (DTP) impregnated on fumed silica0 aSelective hydroxyalkylation of phenol to bisphenol F over dodeca aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB a176-1820 v3543 a

The catalyst activity of various solid acids, such as fumed Silica (SiO(2)) dodecatungstophosphoric acid (DTP), DTP impregnated on SiO(2), amberlyst-15 and montmorillonite KSF/0, was studied for the hydroxyalkylation of phenol to bisphenol F. A well-dispersed DTP on SiO2 catalyst was prepared by the wet impregnation method. The effect of DTP loading on SiO(2) was also compared with bulk DTP and other solid acid catalysts. 20% DTP/SiO(2) catalyst gave the highest products yield of 34.2% and selectivity of 90.1% to bisphenol F, at 353 K and with a phenol-to-formaldehyde mole ratio of 5:1. Ammonia TPD studies of various catalysts showed that an appropriate combination of both strong and weak acid sites of DTP/SiO(2) Was mainly responsible, rather than only the stronger acidity of bulk DTP, for its highest catalytic activity and selectivity. The effect of various reaction parameters like mole ratio, catalyst concentration, temperature and reaction time on product yield and bisphenol F selectivity was also investigated. The catalyst recycle was established by catalyst activity testing. (C) 2008 Elsevier B.V. All rights reserved.

10aBisphenol F10aHydroxyalkylation10aNH(3)-TPD10aReaction pathways10asolid acid catalysts1 aGarade, Ajit, C.1 aKshirsagar, V., S.1 aRode, C., V. uhttp://library.ncl.res.in/content/selective-hydroxyalkylation-phenol-bisphenol-f-over-dodecatungstophosphoric-acid-dtp-002109nas a2200229 4500008004100000022001400041245012000055210006900175260007500244300001200319490000700331520122900338653001901567653002301586653002201609653003301631653002501664100001701689700002101706700002401727856012801751 2009 eng d a1571-101300aSolid acid catalysts: modification of acid sites and effect on activity and selectivity tuning in various reactions0 aSolid acid catalysts modification of acid sites and effect on ac a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGER/PLENUM PUBLISHERScSEP a205-2200 v133 a

The effects of acidity and variation in concentration of acid sites of dodecatungstophosphoric acid (DTP), supported DTP and montmorillonite-K catalysts were studied for various organic reactions such as the hydroxyalkylation of phenols to bisphenols, intramolecular rearrangement of benzyl phenyl ether (BPE) to 2-benzyl phenol (2-BP) and selective cleavage of tert-butyldimethylsilyl (TBDMS) ether into the corresponding alcohol. Both dodecatungstophosphoric acid (DTP) impregnated on silica (SiO(2)) and montmorillonite catalysts showed the highest catalyst activity with 90-95% selectivity to bisphenol for the hydroxyalkylation of phenols to give bisphenol. Temperature Programmed Desorption (TPD) of ammonia and activity results of various catalysts showed that an appropriate combination of both strong and weak acidic sites in the catalyst was highly desirable for high bisphenol selectivity. A 10% DTP/SiO(2) catalyst was found to be highly selective for the cleavage of TBDMS ether into the corresponding alcohol at room temperature giving a high TON of 9.5 x 10(5) even after the 4th recycle. DTP was also found to be a promising solid acid catalyst for the intramolecular rearrangement of BPE giving 2-BP.

10aAcidity tuning10aCatalytic cleavage10aHydroxyalkylation10aIntramolecular rearrangement10asolid acid catalysts1 aRode, C., V.1 aGarade, Ajit, C.1 aChikate, Rajeev, C. uhttp://library.ncl.res.in/content/solid-acid-catalysts-modification-acid-sites-and-effect-activity-and-selectivity-tuning-001558nas a2200241 4500008004100000022001400041245013200055210006900187260007300256300001200329490000700341520067600348653002001024653001401044653002201058653001301080653002501093100002101118700002301139700001401162700001701176856012301193 2010 eng d a1566-736700aStructure-activity studies of dodecatungstophosphoric acid impregnated bentonite clay catalyst in hydroxyalkylation of p-cresol0 aStructureactivity studies of dodecatungstophosphoric acid impreg aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUN a942-9450 v113 a

Bentonite clay impregnated with dodecatungstophosphoric acid (20% DTP/BNT) showed an excellent activity, selectivity and stability [95% product yield with 94% selectivity to 2, 2'-methylenebis (4-methylphenol), DAM] for the hydroxyalkylation of p-cresol with formaldehyde at 353 K and for a mole ratio of 5. Ammonia-TPD results showed that an increase in total concentration of acid sites from 4.9 of parent bentonite to 11.6 micromoles per surface area NH(3) (mu molS(-1) NH(3)) of 20% DTP/BNT was due to a strong interaction of protons of bulk DTP with surface hydroxyl groups of BNT as evidenced by (31)P NMR studies. (C) 2010 Elsevier B.V. All rights reserved.

10a(31)P CPMAS NMR10aBentonite10aHydroxyalkylation10ap-Cresol10asurface modification1 aGarade, Ajit, C.1 aKshirsagar, V., S.1 aJha, Ajay1 aRode, C., V. uhttp://library.ncl.res.in/content/structure-activity-studies-dodecatungstophosphoric-acid-impregnated-bentonite-clay-0