2765-11-9Relevant academic research and scientific papers
Triphasic liquid systems for improved separations. Trioctylmethylammonium chloride-immobilised rhodium trichloride: A phosphine-free hydroformylation catalytic system
Paganelli, Stefano,Perosa, Alvise,Selva, Maurizio
, p. 1858 - 1862 (2007)
A liquid triphasic system made of isooctane, water, and trioctylmethylammonium chloride allows one to carry out the hydroformylation of model olefins using neat RhCl3 as catalyst precursor. By using the triphasic system, the catalyst is kept separate from the reagents and products. This allows one to simply remove the product and to recycle the catalyst numerous times. No leaching of rhodium into the organic phase is observed.
Hydrolytic Stable Ammonium Salts of Sulfonated Organic Phosphites and their Use as Cocatalysts in the Rhodium-catalyzed Hydroformylation of Olefins
Fell, Bernhard,Papadogianakis, Georgios,Konkol, Werner,Weber, Juergen,Bahrmann, Helmut
, p. 75 - 82 (1993)
Ammonium salts of sulfonated organic phosphites, which are resistant to hydrolysis, have been prepared by transesterification of triphenylphosphite with mono-ammonium salt of p-hydroxyphenylsulfonic acid in yields between 66 and 76percent.A mixture containing triisooctylammonium salts of sulfonated triphenylphosphite was submitted to a test for stability to hydrolysis.The time required for hydrolysis of 7.4percent of the TPPp-SO3HN(i-octyl)3 was 3 hours under drastic conditions.Triphenylphosphite was in the same test hydrolyzed quantitatively within three hours.Tetradec-1-ene was hydroformylated by means of the catalytic systems consisting of rhodium-2-ethylhexanoate with either TPPp-SO3HN(i-octyl)3, triphenylphosphite (TPPp) or triphenylphosphine (TPP) at 125 deg C, 0.6 MPa and a rhodium concentration of 50 ppm.Higher reaction selectivities for linear aldehydes were achieved with the rhodium/TPPp-SO3HN(i-octyl)3 catalytic system.Reaction rates increased with the Rh/TPPp-SO3HN(i-octyl)3 catalyst at lower temperature (110 deg C).Using this catalyst at 110 deg C, higher yields are achieved than with the Rh/TPP or Rh/TPPp catalysts.Hex-1-ene was hydroformylated by using the catalytic systems Rh4(CO)12 with TPPp-SO3HN(i-octyl)3, Rh4(CO)12 with TPP or Rh4(CO)12 with TPPp at 125 deg C, 2.5 MPa and a rhodium concentration of 20 ppm.This confirms the above experiments which indicated that higher linear: branched aldehyde ratios were obtained with the rhodium/TPPp-SO3HN(i-octyl)3 catalyst.
Mn(VII) Oxidation using Cetyltrimethylammonium Permanganate: Self-Oxidation of CTAP and Oxidation of Benzyl Alcohol
Dash, Sukalyan,Mishra, Bijay K.
, p. 627 - 636 (1995)
Cetyltrimethylammonium permanganate (CTAP) has been prepared and characterized from IR and NMR data.At room temperature the compound is stable when kept in dark but at 115 deg C it undergoes a violent thermal decomposition.In different organic solvents self-oxidation takes place giving rise to pentadecanal.The rate of self-oxidation in different solvents are in the order: benzonitrile > benzene > chloroform > carbon tetrachloride.A mechanism involving proton transfer from the β-methylene group to the permanganate ion, thereby forming an olefinic intermediate, has been suggested.The oxidation kinetics of benzyl alcohol have been st udied in chloroform medium.The thermodynamic parameters for the oxidation reactions have been evaluated.
β-CD assisted dissolution of quaternary ammonium permanganates in aqueous medium
Bank, Suraj Prakash,Guru, Partha Sarathi,Dash, Sukalyan
, p. 806 - 812 (2014)
The non-polar internal cavity of β-cyclodextrin (β-CD) has been exploited for the entrapment of the hydrophobic tails of two water insoluble quaternary ammonium permanganates (QAPs): cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), for solubilization in aqueous medium. The solubilization and organizational behavior of the QAPs in aqueous β-CD solution have been determined from the comparison of their rates of self-oxidation in presence and in absence of β-CD. Effect of QAP concentration on their observed rate constants (kobs) at a fixed β-CD concentration, phase solubility analysis in varying β-CD concentration, impact of quaternary ammonium bromides (QABs) on the k obs values of CTAP and TBAP at fixed QAP and β-CD concentrations, and the temperature effect have been reported. A scheme to explain the solvation of QAPs in aqueous β-CD has been proposed based on dynamic light scattering (DLS) analysis of the samples.
Hydroformylation with Water- and Methanol-soluble Rhodium Carbonyl/phenyl-sulfonatoalkylphosphine Catalyst Systems - A New Concept for the Hydroformylation of Higher Molecular Olefins
Kanagasabapathy, S.,Xia, Zhigao,Papadogianakis, Georgios,Fell, Bernhard
, p. 446 - 450 (1995)
The heterogenization of the homogenous hydroformylating catalyst system enables the recorvery of the catalyst from the reaction products by a simple phase separation but it is unfavourable that many advantages of the homogeneous catalysis are given up by this procedure.To avoid this drawback we used rhodium carbonyl/tert. phosphine catalyst systems soluble as good in methanol as in water for the homogeneously catalyzed hydroformylation of the olefin in methanolic solution.Only after reaction the product mixture is heterogenized by adding water forming an aqueous phase containing the catalyst system.It was shown by the hydroformylation of n-tetradecene-1 with rhodium carbonyl/phenylsulfonatoalkyl-phosphine catalyst systems that this new conception is very useful for the oxo reaction of high-molecular olefins.
RP-HPLC-fluorescence analysis of aliphatic aldehydes: Application to aldehyde-generating enzymes HACL1 and SGPL1
Mezzar, Serena,De Schryver, Evelyn,Van Veldhoven, Paul P.
, p. 573 - 582 (2014)
Long-chain aldehydes are commonly produced in various processes, such as peroxisomal α-oxidation of long-chain 3-methyl-branched and 2-hydroxy fatty acids and microsomal breakdown of phosphorylated sphingoid bases. The enzymes involved in the aldehyde-generating steps of these processes are 2-hydroxyacyl-CoA lyase (HACL1) and sphingosine-1-phosphate lyase (SGPL1), respectively. In the present work, nonradioactive assays for these enzymes were developed employing the Hantzsch reaction. Tridecanal (C13-al) and heptadecanal (C17-al) were selected as model compounds and cyclohexane-1,3-dione as 1,3-diketone, and the fluorescent derivatives were analyzed by reversed phase (RP)-HPLC. Assay mixture composition, as well as pH and heating, were optimized for C13-al and C17-al. Under optimized conditions, these aldehydes could be quantified in picomolar range and different long-chain aldehyde derivatives were well resolved with a linear gradient elution by RPHPLC. Aldehydes generated by recombinant enzymes could easily be detected via this method. Moreover, the assay allowed to document activity or deficiency in tissue homogenates and fibroblast lysates without an extraction step. In conclusion, a simple, quick, and cheap assay for the study of HACL1 and SGPL1 activities was developed, without relying on expensive mass spectrometric detectors or radioactive substrates. Copyright
Enantioselective syntheses of xylo-C18-phytosphingosines using double stereodifferentiation
Fernandes, Rodney A.,Kumar, Pradeep
, p. 129 - 135 (2003)
The concept of double stereodifferentiation in Sharpless asymmetric dihydroxylation has been studied and the results obtained are applied to the diastereoselective syntheses of xylo-isomers of C18-phytosphingosine. The diastereomeric mixture obtained could be separated by column chromatography. Thus, the L-xylo-(2R,3S,4S)-C18- and D-xylo-(2S,3R,4R)-C18-phytosphingosines as their tetraacetate derivatives were synthesized in diastereomerically pure form.
Double stereodifferentiation in asymmetric dihydroxylation: Application to the first diastereoselective synthesis of L-xylo-[2R,3S,4S]-C18-phytosphingosine
Fernandes, Rodney A.,Kumar, Pradeep
, p. 10309 - 10312 (2000)
The first diastereoselective synthesis of L-xylo-(2R,3S,4S)-C18-phytosphingosine (1) has been achieved by double stereodifferentiation of enantiomerically enriched terminal olefin 14 using (DHQD)2-PHAL ligand in an asymmetric dihydroxylation with a diastereomeric ratio of 83:17. This phytosphingosine was fully characterized by the physical and spectral data of the corresponding tetraacetate 21. (C) 2000 Elsevier Science Ltd.
Free-of-loss catalyst recycling in the hydroformylation of higher molecular olefins by a novel process technology
Xia, Zhigao,Fell, Bernhard
, p. 140 - 144 (1997)
In this paper a novel homogenous-heterogeneous procedure for the hydroformylation reaction of higher molecular olefins is presented, at which the reaction itself is homogeneously catalyzed and only after the reaction the catalyst complex is heterogenized only for separation. This procedure is achieved by using the lithium salt of triphenylphosphine monosulfonic acid (Li-TPPMS) as complex ligand for the hydroformylation catalyst and methanol as solubilizer. Li-TPPMS and its complexes with metal carbonyls are highly soluble in water and methanol, but completely insoluble in almost all other organic solvents. After the reaction the methanol is distilled off. The catalyst system becomes insoluble and can be separated from the reaction product by filtration or by extraction with water. The aqueous catalyst solution is evaporated to dryness and the catalyst system dissolved in methanol for a new reaction. Johann Ambrosius Barth 1997.
VOLATILES FROM WINTER WHEAT: IDENTIFICATION OF ADDITIONAL COMPOUNDS AND EFFECTS OF TISSUE SOURCE
Hamilton-Kemp, Thomas R.,Andersen, Roger A.
, p. 241 - 243 (1986)
Sixteen volatile compounds have been identified in oil prepared from winter wheat by reduced pressure steam distillation-extraction.Most of these compounds were found in relatively small quantities (0.5percent or less) with the exception of pentadecanal.Comparisons were also made of the relative amounts of C9 alcohols and aldehydes obtained from fresh versus frozen plants, cut versus intact plants and leaves versus culms. Key Word Index - Triticum aestivum; Gramineae; wheat; volatiles; pentadecanal; host-parasite interactions.
