104870-56-6Relevant articles and documents
Diiodosamarium, a unique catalyst precursor for ene reactions of unsaturated carbonyl compounds
Sarkar, Tarun K.,Nandy, Sandip K.
, p. 5195 - 5198 (1996)
SmI2 presents catalytic activity for ene cyclizations of a series of unsaturated carbonyl compounds, some of which are prone to rearrangement or polymerization under standard conditions.
Comparison of acidic site quantification methods for a series of nanoscopic aluminum hydroxide fluorides
Hemmann, Felix,Jaeger, Christian,Kemnitz, Erhard
, p. 56900 - 56909 (2014)
Quantitative determination of acidic surface sites is highly important for the characterization of solid acids because the activity of a catalyst is often related to the concentration of these sites. A recently developed method using 15N Nuclear Magnetic Resonance spectroscopy (NMR) for the quantification of acidic Lewis and Bronsted sites has been tested for a series of nanoscopic aluminum hydroxide fluorides. Comparison with other methods for the quantitative determination of acidic sites shows that this 15N NMR quantification method is a promising technique for the comprehensive investigation of acidic sites. Three different acidic sites, one Bronsted and two Lewis sites, can be distinguished by their 15N chemical shifts of pyridine and simultaneously quantified under conditions corresponding to catalytic reaction conditions. Determination of the individual concentrations of acidic sites allows further insight into the catalytic process. It was found that the concentration of Bronsted sites correlates with catalyzed conversion of citronellal to isopulegol in the investigated series of catalysts. Additionally, investigations indicate that one of the Lewis sites become blocked during the reaction of citronellal.
Metal Nanoparticles Supported on Perfluorinated Superacid Polymers: A Family of Bifunctional Catalysts for the Selective, One-Pot Conversion of Vegetable Substrates in Water
Moreno-Marrodan, Carmen,Liguori, Francesca,Barbaro, Pierluigi,Caporali, Stefano,Merlo, Luca,Oldani, Claudio
, p. 4256 - 4267 (2017)
We describe the rational design of a new versatile family of bifunctional catalytic materials based on the combination of supported metal nanoparticles (Pd, Rh, Ru) and the superacid, perfluorinated Aquivion PFSA polymer. The heterogeneous catalysts were tested in the multi-step valorisation of representative plant derivatives to high-added-value chemicals. Particularly, the conversion of (+)-citronellal to (-)-menthol and levulinic acid to γ-valerolactone was achieved in one pot and in one stage in the water phase and shows full selectivity at a high conversion level under mild reaction conditions. The results are discussed in terms of the catalyst micro-structure.
Cyclization of citronellal over zeolites and mesoporous materials for production of isopulegol
Maeki-Arvela, Paeivi,Kumar, Narendra,Nieminen, Ville,Sjoeholm, Rainer,Salmi, Tapio,Murzin, Dmitry Yu.
, p. 155 - 169 (2004)
Cyclization of (+)-citronellal was investigated over zeolites and mesoporous materials as well as on silica under a nitrogen atmosphere in cyclohexane as a solvent. The highest cyclization rates were observed over mesoporous materials and 12-membered ring zeolites with high Bronsted acid concentration, while very low cyclization rates were achieved over silica with low or no Bronsted acidity, respectively. At the same a time low cyclization rate was observed over 10-membered ring pore H-ZSM-5 with a high Bronsted acid site concentration, which is due to diffusional limitation of the product in the narrow pores. The selectivity to cyclization products was very high over all the catalysts, being independent of the conversion of citronellal. Neither concentration of the Bronsted nor Lewis acid sites influenced the stereoselectivity to isopulegol. The support structure had only a minor effect on the stereoselectivity. Quantum mechanical calculations were carried out to explain the experimental results. The calculated stabilities of the carbocationic reaction intermediates correlated well with the observed stereoselectivity. The stereoselectivities were analogous when starting from racemic citronellal mixture or enantiopure (+)-citronellal; the former one gave 8 different pulegols, whereas only 4 pulegols were formed from (+)-citronellal.
Highly selective menthol synthesis by one-pot transformation of citronellal using Ru/H-BEA catalysts
Pl?sser, Jutta,Lucas, Martin,Claus, Peter
, p. 189 - 197 (2014)
The one-pot transformation of citronellal to menthol requires a combined cyclization-hydrogenation step for which Ru/H-BEA catalysts were identified as highly active and selective catalysts. After identifying zeolite H-BEA as the most promising heterogeneous catalyst for the cyclization of citronellal to the intermediate isopulegol, bifunctional metal/H-BEA catalysts were investigated in the one-pot transformation of citronellal to menthols. Using Pd undesired defunctionalization prevailed, while using Pt and Ru, the formation of menthols predominated. Finally, for Ru/H-BEA catalysts, the effect of catalyst composition (Si:Al ratio, Ru content) and reaction conditions (temperature, hydrogen pressure, and solvent) was investigated to diminish citronellal hydrogenation, dimerization, and defunctionalization. Accordingly, with a 1%Ru/H-BEA-25 catalyst (Ru particle size = 1 nm) in dioxane at 15 bar hydrogen pressure and 373 K, a very high selectivity to menthols of 93% at nearly full conversion was obtained. The catalyst is also highly diastereoselective producing 79% of the desired (±)-menthol.
Synergy between Bronsted acid sites and Lewis acid sites
Telalovic, Selvedin,Ng, Jeck Fei,Maheswari, Rajamanickam,Ramanathan, Anand,Chuah, Gaik Khuan,Hanefeld, Ulf
, p. 4631 - 4633 (2008)
Synergy between Bronsted acid sites and Lewis acid sites in mesoporous Al-Zr-TUD-1 was demonstrated to exist in Bronsted acid catalysed reactions, but not in Lewis acid catalysed reactions. The Royal Society of Chemistry.
Cyclization of citronellal to p-menthane-3,8-diols in water and carbon dioxide
Cheng, Haiyang,Meng, Xiangchun,Liu, Ruixia,Hao, Yufen,Yu, Yanchun,Cai, Shuxia,Zhao, Fengyu
, p. 1227 - 1231 (2009)
A clean process has been developed for the synthesis of p-menthane-3,8-diols from cyclization of citronellal in CO2-H 2O medium without any additives. With the addition of CO2, the reaction rate could be enhanced about 6 t
Zr-zeolite beta: A new heterogeneous catalyst system for the highly selective cascade transformation of citral to (±)-menthol
Nie, Yuntong,Jaenicke, Stephan,Chuah, Gaik-Khuan
, p. 1991 - 1999 (2009)
The transformation of citral to menthols involves hydrogenation steps as well as cyclisation of the intermediate, citronellal. The ability of Zrzeolite beta to catalyse the cyclisation with high diastereoselectivity to (±)-isopulegol is the critical step
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Dolby,L.J.,Debono,M.
, p. 2306 - 2310 (1964)
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Zr-TUD-1: A lewis acidic, three-dimensional, mesoporous, zirconium-containing catalyst
Ramanathan, Anand,Carmen Castro Villalobos,Kwakernaak, Cees,Telalovic, Selvedin,Hanefeld, Ulf
, p. 961 - 972 (2008)
A three-dimensional, mesoporous, silicate containing zirconium, Zr-TUD-1, was synthesized by a direct hydrothermal treatment method with triethanolamine as a complexing and templating reagent to ensure that zirconium was incorporated as isolated atoms. The mesoporosity of Zr-TUD-1 was confirmed by X-ray diffraction (XRD), N2 sorption and high-resolution transmission electron micrograph (HR-TEM) studies. The nature and strength of the Lewis acid sites present in Zr-TUD-1 were evaluated by FTIR studies of pyridine adsorption and temperature-programmed desorption of ammonia. FTIR, X-ray photoelectron spectroscopic (XPS) and UV/Vis spectroscopic studies showed that, at Si/Zr ratios of 25 and higher, all the zirconium was tetrahedrally incorporated into the mesoporous framework, while at low Si/Zr ratios, a small part of the zirconium was present as ZrO2 nanoparticles. Zr-TUD-1 is a Lewis acidic, stable and recyclable catalyst for the Meerwein-Ponndorf-Verley (MPV) reaction and for the Prins reaction.
Unveiling reactive metal sites in a Pd pincer MOF: Insights into Lewis acid and pore selective catalysis
Reiner, Benjamin R.,Kassie, Abebu A.,Wade, Casey R.
, p. 9588 - 9595 (2019)
A porous Zr metal-organic framework, 1-PdBF4 [Zr6O4(OH)4(OAc)2.4{(PNNNP)Pd(MeCN)}2.4(BF4)2.4; PNNNP = 2,6-(HNPAr2)2C5H3N; Ar = p-C6H4CO2-], has been synthesized via postsynthetic oxidative I-/BF4- ligand exchange using NOBF4. 1-PdBF4 enjoys markedly superior catalytic activity and recyclability to its trifluoracetate-exchanged analogue, 1-PdTFA, for the intramolecular cyclization of o-alkynyl anilines and the carbonyl-ene cyclization of citronellal. Moreover, 1-PdBF4 demonstrates a rare example of pore selective catalysis for the cyclization of 2-ethynyl aniline.
One-pot synthesis of menthol catalyzed by a highly diastereoselective Au/MgF2 catalyst
Negoi, Alina,Wuttke, Stefan,Kemnitz, Erhard,MacOvei, Dan,Parvulescu, Vasile I.,Teodorescu,Coman, Simona M.
, p. 8134 - 8138 (2010)
No toxic compounds such as KCN and no thermal activation is required for the preparation of Au/MgF2 complexes by a simple and facile incipient wetness impregnation method in which hydrogen tetrachloroaurate (HAuCl 4) is the gold precursor. One of the complexes prepared exhibits unique catalytic properties and serves as a heterogeneous catalyst for the highly diastereoselective one-pot synthesis of (±)-menthol from citronellal (see picture).
Electronic effects of linker substitution on Lewis acid catalysis with metal-organic frameworks
Vermoortele, Frederik,Vandichel, Matthias,Van De Voorde, Ben,Ameloot, Rob,Waroquier, Michel,Van Speybroeck, Veronique,De Vos, Dirk E.
, p. 4887 - 4890 (2012)
Functionalized linkers can greatly increase the activity of metal-organic framework (MOF) catalysts with coordinatively unsaturated sites. A clear linear free-energy relationship (LFER) was found between Hammett m values of the linker substituents X and the rate kX of a carbonyl-ene reaction. This is the first LFER ever observed for MOF catalysts. A 56-fold increase in rate was found when the substituent is a nitro group (see picture). Copyright
Cyclisation of citronellal over heterogeneous inorganic fluorides - Highly chemo- and diastereoselective catalysts for (±)-isopulegol
Coman, Simona M.,Patil, Pratap,Wuttke, Stefan,Kemnitz, Erhard
, p. 460 - 462 (2009)
Based on a fluorolytic sol-gel synthesis, nanoscopic metal fluorides and partly hydroxylated metal fluorides were synthesized; varying the F: OH ratio inside these solids yielded catalysts with different combinations and variable strength Lewis and Br?nsted acid sites, which demonstrated unexpected catalytic properties for the diastereoselective synthesis of (±)-isopulegol. The Royal Society of Chemistry.
Flow Pickering Emulsion Interfaces Enhance Catalysis Efficiency and Selectivity for Cyclization of Citronellal
Chen, Huan,Zou, Houbing,Hao, Yajuan,Yang, Hengquan
, p. 1989 - 1995 (2017)
Cyclization of citronellal is a necessary intermediate step to produce the important flavor chemical (?)-menthol. Here, a continuous-flow Pickering emulsion (FPE) strategy for selective cyclization of citronellal to (?)-isopulegol by using water droplets hosting a heteropolyacid (HPA) catalyst to fill a column reactor is demonstrated. Owing to the large liquid–liquid interface and the excellent confinement ability of droplets toward HPA, the FPE system exhibited a much higher catalysis efficiency than its batch counterpart (2–5-fold) and an excellent durability (two months). Moreover, a remarkably enhanced selectivity was observed from 34.8 % for batch reactions to 64 % for the FPE reactions. It was found that the water droplet size and the flow rate significantly impact the catalysis selectivity and efficiency. This study not only represents an unprecedented and sustainable process for the selective cyclization of citronellal but also demonstrates a new flow-interface catalysis effect that can be useful for designing innovative catalysis systems in the future.
B-TUD-1: A versatile mesoporous catalyst
Ranoux, Adeline,Djanashvili, Kristina,Arends, Isabel W.C.E.,Hanefeld, Ulf
, p. 21524 - 21534 (2013)
Novel amorphous mesoporous borosilicate, B-TUD-1, was prepared to test its performance for different sustainable reactions. The structure of the material, the effective incorporation of boron into the framework as well as the nature of incorporated boron were verified by N2-sorption, XRD, ICP-OES, TEM, NH3-desorption, MAS NMR and FTIR. The potential of these materials as catalysts was tested in two reactions under different conditions. They showed an apparently good activity and recycling potential for HMF (5-hydroxymethyl- furfural) synthesis. However leaching of boron occurred during this aqueous reaction. We could demonstrate that the leached boron was actually the catalyst of the reaction. In a second reaction, this time in organic solvent, the B-TUD-1 materials were tested for the Prins cyclisation of citronellal. A very promising activity was obtained. The catalyst could be recycled and no boron leached, as demonstrated by hot filtration experiments. The Royal Society of Chemistry 2013.
Selectivity in the Cyclization of Citronellal Introduced by Squalene Hopene Cyclase Variants
Bastian, Silke A.,Hammer, Stephan C.,Kre?, Nico,Nestl, Bettina M.,Hauer, Bernhard
, p. 4364 - 4368 (2017)
The squalene hopene cyclase from Alicyclobacillus acidocaldarius (AacSHC) is a highly efficient enzyme catalyst for stereoselective Br?nsted acid catalysis. We engineered AacSHC to catalyze the selective Prins cyclization of citronellal. Four active site variants were identified for the diastereoselective cyclization of (S)-citronellal to stereoisomers (?)-iso-isopulegol, (+)-isopulegol and (?)-neo-isopulegol, respectively. The replacement of active site residues resulted in two triple variants that catalyzed the transformation of (R)-citronellal to give the isomers (+)-neo-isopulegol and (?)-isopulegol with up to >99 % de, respectively. The newly designed library of functionally diverse active site geometries exhibits high selective control during citronellal cyclization, leading exclusively to a single diastereomer of the desired isopulegol. Whereas the cyclization of citronellal with chemical catalysts was observed to produce the isopulegol isomer with the lowest energy, the reaction with AacSHC variants proceeded with higher product selectivity. The results of this study show that variants of AacSHC are excellent catalysts for the highly selective formation of isopulegol stereoisomers.
Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalyst
Er?nen, Kari,M?ki-Arvela, P?ivi,Martinez-Klimov, Mark,Muller, Joseph,Murzin, Dmitry Yu.,Peurla, Markus,Simakova, Irina,Vajglova, Zuzana
, (2022/04/03)
One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties.
Method for improving optical purity of L-isopulegol through chiral resolution
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Paragraph 0056; 0057; 0058, (2019/02/10)
The invention provides a method for improving the optical purity of L-isopulegol through chiral resolution. The method comprises the following steps: putting D,L-isopulegol and a resolution agent L-linalool into a dispersant and an auxiliary agent and reacting for 3 to 4 hours at 70 to 80 DEG C; after cooling to 10 to 25 DEG C, centrifuging and separating to obtain an intermediate L-isopulegol.L-linalool; carrying out alkali analysis on the intermediate; decomposing the intermediate; then carrying out gel chromatography to obtain the high-purity L-isopulegol. The method has the advantages of low raw material cost and low reaction energy consumption and is applicable to large-scale industrialized production.
