01860nas a2200253 4500008004100000022001400041245012300055210006900178260007300247300001200320490000600332520095300338653001501291653001501306653001101321653002401332653002301356653002801379100001901407700001701426700001701443700001801460856012801478 2005 eng d a1566-736700aInfluence of alkali metal doping on selectivity behaviour of platinum catalysts for hydrogenation of 2-butyne-1,4-diol0 aInfluence of alkali metal doping on selectivity behaviour of pla aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV a725-7300 v63 a

Hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol (B(2)D) and butane-1,4-diol (B(1)D) using Pt catalysts doped with alkali metals was studied. These catalysts showed higher selectivity to the olefinic diol (B2D) compared to that with monometallic platinum catalyst. Among various alkali metals, Cs-doped catalyst showed highest selectivity (>99%) to B(2)D. The selectivity to B(2)D increased (up to 99.9%) with increase in the concentration of Cs from 0.25% to 1%. The increase in the basic strength of alkali doped catalysts measured by CO(2)-TPD, would be responsible for the increase in electron density of Pt hence, faster desorption and higher selectivity to the intermediate olefinic diol (B(2)D). The reaction parameters; such as temperature, H(2) pressure and substrate concentration haye strong influence on the catalyst activity but almost no effect on the selectivity to B(2)D. (c) 2005 Elsevier B.V. All rights reserved.

10a2-butene-110a2-butyne-110a4-diol10aalkali metal doping10aplatinum catalysts10aSelective hydrogenation1 aTelkar, M., M.1 aRode, C., V.1 aRane, V., H.1 aChaudhari, R. uhttps://library.ncl.res.in/content/influence-alkali-metal-doping-selectivity-behaviour-platinum-catalysts-hydrogenation-2-001222nas a2200229 4500008004100000022001400041245005200055210004800107260010600155300001400261490000700275520043200282653001100714653001900725653003800744653001900782653002800801653004100829100002400870700001600894856008200910 2005 eng d a0040-403900aStereoselective synthesis of (-)-microcarpalide0 aStereoselective synthesis of microcarpalide aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR a1939-19410 v463 a

A highly convergent and efficient synthesis of (-)-microcarpalide, a 10-membered lactone displaying remarkable microfilament disrupting activity is described. Ring-closing metathesis and Sharpless asymmetric dihydroxylations are the key steps. Our strategy highlights the application of novel hydroxy lactone precursors for the stereoselective synthesis of (-)-microcarpalide. (C) 2005 Elsevier Ltd. All rights reserved.

10a4-diol10acis-2-butene-110aClaisen ortho ester rearrangement10amicrocarpalide10aRing-closing metathesis10asharpless asymmetric dihydroxylation1 aChavan, Subhash, P.1 aPraveen, C. uhttps://library.ncl.res.in/content/stereoselective-synthesis-microcarpalide-002888nas a2200229 4500008004100000022001400041245009300055210006900148260010800217300001200325490000700337520201400344653001502358653001502373653001102388653002402399653002602423653002802449653002802477100002902505856012402534 2008 eng d a1346-880400aCatalytic hydrogenation of 2-butyne-1,4-diol: activity, selectivity and kinetics studies0 aCatalytic hydrogenation of 2butyne14diol activity selectivity an aYOYU-KANDA BLDG. 4F, 1-8-4 KANDASUDA-CHO, CHIYODA-KU, TOKYO, 108-0041, JAPANbJAPAN PETROLEUM INSTcMAY a119-1330 v513 a

The reaction pathway for hydrogenation of 2-butyne-1,4-diol involves parallel and consecutive isomerization as well as hydrogenation reactions forming other side products along with cis-2-butene-1,4-diol and butane-1,4-diol. Hence, achieving the highest selectivity to butene- and/or butanediol is critical from industrial point of view. Hydrogenation of butynediol is also of fundamental significance, due to its adsorption characteristics leading to the formation of active species and their role in determining the product distribution. Studies on designing various catalyst systems including colloidal as well supported palladium nanoparticles for the hydrogenation of butynediol, role of additives, catalyst pretreatment, kinetic studies carried out in our group has been presented in this review. Interestingly, almost complete selectivity to the intermediate olefinic diol was achieved with 1% Pd/CaCO3-NH3 catalyst system. This could be due to the competitive adsorption of ammonia on the palladium surface along with the substrate 2-butyne-1,4-diol. Studies on catalyst pretreatment and kinetics using palladium catalyst have also been presented here. Nanostructure palladium both colloidal as well as supported catalysts showed a very high catalytic activity (10-40 times more) in the hydrogenation 2-butyne-1,4-diol to cis-2-butene-1,4-diol compared with the corresponding conventional Pd catalysts. For platinum based catalysts, formation of side products was completely eliminated in the hydrogenation of butyne diol. The increase in the basic strength of alkali metal doped Pt catalysts measured by CO2-TPD, led to the increase in electron density of Pt hence, faster desorption and higher selectivity to butenediol. In the case of continuous hydrogenation, the selectivity pattern was completely different from that found in the case of batch slurry reactor and by varying the contact time, the selectivity to both butene- and butanediols could be varied over a wide range of conditions.

10a2-butene-110a2-butyne-110a4-diol10aalkali metal doping10acatalyst pretreatment10anano palladium catalyst10aSelective hydrogenation1 aRode, Chandrashekhar, V. uhttps://library.ncl.res.in/content/catalytic-hydrogenation-2-butyne-14-diol-activity-selectivity-and-kinetics-studies-0