- Triphasic liquid systems for improved separations. Trioctylmethylammonium chloride-immobilised rhodium trichloride: A phosphine-free hydroformylation catalytic system
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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.
- Paganelli, Stefano,Perosa, Alvise,Selva, Maurizio
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- Hydrolytic Stable Ammonium Salts of Sulfonated Organic Phosphites and their Use as Cocatalysts in the Rhodium-catalyzed Hydroformylation of Olefins
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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.
- Fell, Bernhard,Papadogianakis, Georgios,Konkol, Werner,Weber, Juergen,Bahrmann, Helmut
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- Mn(VII) Oxidation using Cetyltrimethylammonium Permanganate: Self-Oxidation of CTAP and Oxidation of Benzyl Alcohol
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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.
- Dash, Sukalyan,Mishra, Bijay K.
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- β-CD assisted dissolution of quaternary ammonium permanganates in aqueous medium
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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.
- Bank, Suraj Prakash,Guru, Partha Sarathi,Dash, Sukalyan
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- Hydroformylation with Water- and Methanol-soluble Rhodium Carbonyl/phenyl-sulfonatoalkylphosphine Catalyst Systems - A New Concept for the Hydroformylation of Higher Molecular Olefins
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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.
- Kanagasabapathy, S.,Xia, Zhigao,Papadogianakis, Georgios,Fell, Bernhard
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- RP-HPLC-fluorescence analysis of aliphatic aldehydes: Application to aldehyde-generating enzymes HACL1 and SGPL1
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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
- Mezzar, Serena,De Schryver, Evelyn,Van Veldhoven, Paul P.
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- Enantioselective syntheses of xylo-C18-phytosphingosines using double stereodifferentiation
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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.
- Fernandes, Rodney A.,Kumar, Pradeep
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- Double stereodifferentiation in asymmetric dihydroxylation: Application to the first diastereoselective synthesis of L-xylo-[2R,3S,4S]-C18-phytosphingosine
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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.
- Fernandes, Rodney A.,Kumar, Pradeep
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- Free-of-loss catalyst recycling in the hydroformylation of higher molecular olefins by a novel process technology
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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.
- Xia, Zhigao,Fell, Bernhard
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- VOLATILES FROM WINTER WHEAT: IDENTIFICATION OF ADDITIONAL COMPOUNDS AND EFFECTS OF TISSUE SOURCE
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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.
- Hamilton-Kemp, Thomas R.,Andersen, Roger A.
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- Integration of phosphine ligands and ionic liquids both in structure and properties-a new strategy for separation, recovery, and recycling of homogeneous catalyst
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The major limitation of classic biphasic ionic liquid (IL) catalysis is the heavy use of solvent ILs, which not only violates green chemistry principles but also even worsens catalytic efficiency. So it has always been a challenge finding ways to use ILs more efficiently, economically, and greenly to construct highly effective and long term stable IL catalytic systems. In this work, we synthesized a class of room temperature phosphine-functionalized polyether guanidinium ionic liquids (RTP-PolyGILs) by a convenient ion exchange reaction of polyether guanidinium ionic liquids (PolyGILs) with phosphine-sulfonate ligands based on the concept of the integration of both the phosphine ligand and IL. The resulting RTP-PolyGILs existed as liquids at room temperature and possessed dual functions of both the phosphine ligand and solvent IL; therefore they could both form catalysts by complexing with transition metals and act as catalyst carriers, thus achieving the integration of phosphine ligands with ILs both in structure and properties. Based on the unique properties of these multi-functional integrated RTP-PolyGILs, we constructed a highly effective homogeneous catalysis-biphasic separation (HCBS) system for Rh-catalyzed hydroformylation of higher olefins using only a catalytic amount of RTP-PolyGILs (equivalent to 0.025-0.4 mol% of 1-alkenes). Our HCBS system could be flexibly regulated with regard to catalytic performance (activity and linear selectivity) by changing the structure or type of the sulfonated ligand anion on RTP-PolyGILs. Specifically, it presented a TOF value of 3000-26000 h-1 and a linear selectivity of 68%-98% (corresponding to the l/b ratio of 2.2-37.5) with a total turnover number (TTON) of 11000-45000 and an extremely low Rh leaching of only 0.02-0.4 ppm. Therefore, the HCBS system can effectively combine the advantages of both homogeneous (high activity and good selectivity) and biphasic catalysis (easy catalyst separation). We additionally extended the application of the HCBS system to the hydrogenation of olefins to demonstrate the universality of the RTP-PolyGILs in catalytic reactions.
- Jin, Xin,Feng, Jianying,Song, Hongbing,Yao, Jiajun,Ma, Qingqing,Zhang, Mei,Yu, Cong,Li, Shumei,Yu, Shitao
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p. 3583 - 3596
(2019/07/10)
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- Based on [...] functionalized polyether alkyl guanidine salt ion liquid of the two-phase hydroformylation of olefins method
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The present invention relates to a method for biphasic hydroformaylation of olefins based on a phosphine-functionalized polyether alkyl guanidine salt ionic liquid. A biphasic catalytic system is used in the method, wherein the catalytic system consists of the phosphine-functionalized polyether alkyl guanidine salt ionic liquid, a rhodium catalyst, a reaction substrate - olefins and a reaction product - aldehydes; liquid/liquid biphasic hydroformylation of olefins is performed at a certain reaction temperature and syngas pressure; the phosphine-functionalized polyether alkyl guanidine salt ionic liquid acts both as a phosphine ligand and as a rhodium catalyst carrier; there is no need to add any other ionic liquid to the system; separation and recycling of the rhodium catalyst are realized by liquid/liquid biphasic separation after the reaction; the rhodium catalyst is capable of being recycled for multiple times with no obvious decrease in catalytic activity or selectivity; the TOF value of the system reaches 240-2700h-1; and the highest catalytic cycle cumulative TON value reaches 47138.
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Paragraph 0053; 0063; 0064; 0065
(2018/09/26)
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- A kind of [...] functionalized polyether pyridine salt ion liquid and its olefin hydroformylation reaction in the application of the
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The present invention relates to a phosphine-functionalized polyether pyridinium salt ionic liquid and a method for biphasic hydroformaylation of olefins based on the phosphine-functionalized polyether pyridinium salt ionic liquid. A biphasic catalytic system is used in the method, wherein the catalytic system consists of a phosphine-functionalized polyether pyridinium salt ionic liquid, a rhodium catalyst, a reaction substrate, olefins, and a reaction product, aldehydes; liquid/liquid biphasic hydroformylation of olefins is performed at a certain reaction temperature and syngas pressure; the phosphine-functionalized polyether pyridinium salt ionic liquid acts both as a phosphine ligand and as a rhodium catalyst carrier; there is no need to add any other ionic liquid to the system; and separation and recycling of the rhodium catalyst are realized by liquid/liquid biphasic separation after the reaction. The catalytic system provided by the present invention is high in catalytic activity. The rhodium catalyst is capable of being recycled for many times with no obvious decrease in catalytic activity or selectivity.
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Paragraph 0063; 0064; 0074; 0076
(2018/05/24)
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- Convergent synthesis of a deuterium-labeled serine dipeptide lipid for analysis of biological samples
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Bacterial serine dipeptide lipids are known to promote inflammatory processes and are detected in human tissues associated with periodontal disease or atherosclerosis. Accurate quantification of bacterial serine lipid, specifically lipid 654 [((S)-15-methyl-3-((13-methyltetradecanoyl)oxy)hexadecanoyl)glycyl-l-serine, (3S)-l-serine] isolated from Porphyromonas gingivalis, in biological samples requires the preparation of a stable isotope internal standard for sample supplementation and subsequent mass spectrometric analysis. This report describes the convergent synthesis of a deuterium-substituted serine dipeptide lipid, which is an isotopically labeled homologue that represents a dominant form of serine dipeptide lipid recovered in bacteria.
- Dietz, Christopher,Clark, Robert B.,Nichols, Frank C.,Smith, Michael B.
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p. 274 - 285
(2017/05/29)
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- Water-soluble phosphane-substituted cyclodextrin as an effective bifunctional additive in hydroformylation of higher olefins
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In cyclodextrin (CD)-mediated aqueous biphasic catalysis, favoring contacts between the CD ("host"), the organic substrate ("guest") and the water-soluble catalyst is crucial for the reaction to proceed efficiently at the aqueous/organic interface. Grafting the catalyst onto the CD backbone thus appears as an attractive approach to favor the molecular recognition of the substrate and its subsequent catalytic conversion into products. In this context, a new water-soluble β-CD-based phosphane was synthesized and characterized by NMR, tensiometric and ITC measurements. The β-CD-based phosphane consisted of a 3,3′-disulfonatodiphenyl phosphane connected to the primary face of β-CD by a dimethyleneamino spacer. Intra- and intermolecular inclusion processes of one of the two sulfophenyl groups into the β-CD cavity were identified in water. However, the association constant (Ka) related to the β-CD/sulfophenyl group couple was low. Accordingly, the inclusion process was easily displaced upon coordination to rhodium complexes. The efficacy of the resulting Rh-complex coordinated by β-CD-based phosphanes was assessed in Rh-catalyzed hydroformylation of higher olefins. The catalytic system proved to be far more successful and efficient than a system consisting of supramolecularly interacting phosphanes and CDs. The catalytic activity was up to 30-fold higher while the chemo- and regioselectivities remain rather unchanged.
- Leblond,Potier,Menuel,Bricout,Machut-Binkowski,Landy,Tilloy,Monflier,Hapiot
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p. 3823 - 3830
(2017/09/07)
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- A kind of [...] functionalized polyether quaternary phosphonium ionic liquid and its olefin hydroformylation reaction in the application of the (by machine translation)
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The invention relates to a functionalized polyether quaternary phosphonium salt [...] ionic liquid, and a functionalized polyether quaternary phosphonium salt based on [...] ionic liquid two-phase hydroformylation of olefins of the method, the method uses a two-phase catalytic system, the catalytic system is composed of [...] functionalized polyether quaternary phosphonium ion liquid, rhodium catalyst and reaction substrate olefin and reaction aldehyde composition, in a certain reaction temperature and the synthesis gas is conducted under a pressure liquid/liquid two-phase hydroformylation reaction, [...] functionalized polyether quaternary phosphonium ionic liquid is phosphine, at the same time also acts as the rhodium catalyst carrier, system do not need in in addition introducing other ionic liquid, after the reaction through a simple liquid/liquid two-phase separation [...] separation and recycle of the catalyst, the catalytic system has higher catalytic activity, rhodium catalyst can be circulated many times, catalytic activity and selectivity without significant decrease. (by machine translation)
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Paragraph 0070-0072
(2017/11/16)
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- Tetronics/cyclodextrin-based hydrogels as catalyst-containing media for the hydroformylation of higher olefins
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The rhodium-catalyzed hydroformylation of alkenes has been investigated under biphasic conditions using combinations of α-cyclodextrin (α-CD) and poloxamines (Tetronics). Thermo-responsive hydrogels containing the Rh-catalyst are formed under well-defined conditions of concentration. Hydrogels consisting of the reverse-sequential Tetronic 90R4 prove to be more effective than those containing the conventional sequential Tetronic 701. The presence of α-CD is crucial to provoke the decantation of the multiphasic system once the reaction is complete. Optimized conditions (CO/H2 pressure, Rh-precursors, phosphanes, etc.) show that the catalytic system is especially applicable to the hydroformylation of terminal alkenes. The catalytic performance remains unchanged upon recycling as the hydrogel matrix prevents the oxidation of the phosphane.
- Chevry,Vanbésien,Menuel,Monflier,Hapiot
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p. 114 - 123
(2017/08/14)
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- A kind of [...] functionalized polyether piperidine salt ion liquid and its olefin hydroformylation reaction in the application of the
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The present invention relates to a phosphine-functionalized polyether piperidine salt ionic liquid and a method for biphasic hydroformaylation of olefins based on the phosphine-functionalized polyether piperidine salt ionic liquid. The method uses a biphasic catalytic system, wherein the catalytic system consists of a phosphine-functionalized polyether piperidine salt ionic liquid, a rhodium catalyst, the reaction substrate, olefins and the reaction product, aldehydes; liquid/liquid biphasic hydroformylation of olefins is performed at a certain reaction temperature and syngas pressure; the phosphine-functionalized polyether piperidine salt ionic liquid acts both as a phosphine ligand and as a rhodium catalyst carrier; there is no need to add any other ionic liquid to the system; and separation and recycling of the rhodium catalyst are realized by liquid/liquid biphasic separation after the reaction. The catalytic system provided by the present invention is high in catalytic activity. The rhodium catalyst is capable of being recycled for many times with no obvious decrease in catalytic activity and selectivity.
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Paragraph 0067-0069; 0079-0081
(2017/11/16)
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- Chemo- and Diastereoselective N-Heterocyclic Carbene-Catalyzed Cross-Benzoin Reactions Using N-Boc-α-amino Aldehydes
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N-Boc-α-amino aldehydes are shown to be excellent partners in cross-benzoin reactions with aliphatic or heteroaromatic aldehydes. The chemoselectivity of the reaction and the facial selectivity on the amino aldehyde allow cross-benzoin products to be obtained in good yields and good diastereomeric ratios. The developed method is utilized as the key step in a concise total synthesis of d-arabino-phytosphingosine.
- Haghshenas, Pouyan,Gravel, Michel
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supporting information
p. 4518 - 4521
(2016/09/28)
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- Method for high-selectivity preparation of normal aldehyde through olefin two-phase hydroformylation on basis of polyether alkyl guanidinium ionic liquid
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The invention relates to a method for high-selectivity preparation of normal aldehyde through olefin two-phase hydroformylation on the basis of a polyether alkyl guanidinium ionic liquid. According to the method, a two-phase catalytic system is adopted, the catalytic system comprises a polyether alkyl guanidinium ionic liquid PGILs with room temperature liquid-solid phase change characteristics, a rhodium catalyst, diphosphine ligands, a reaction substrate olefin and a reaction product aldehyde, a liquid/liquid two-phase hydroformylation reaction is performed at certain reaction temperature and under certain synthesis gas pressure, and the rhodium catalyst is recovered and cycled through simple two-phase separation after the reaction ends. The catalytic system has high catalytic activity with, high selectivity, ultralong service life and very low rhodium catalyst loss amount, wherein the TOF value reaching 130-240 h; the area selectivity of normal aldehyde reaches 96%-98%; the catalytic cycle accumulated TON value is 40,000 or above at most; the rhodium catalyst loss amount is only 0.02%-0.1%.
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Paragraph 0076-0078
(2017/01/09)
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- Method for high-selectivity preparation of normal aldehyde through olefin two-phase hydroformylation on basis of polyether pyridinium ionic liquid
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The invention relates to a method for high-selectivity preparation of normal aldehyde through olefin two-phase hydroformylation on the basis of a polyether pyridinium ionic liquid. According to the method, a two-phase catalytic system is adopted, the catalytic system comprises a polyether pyridinium ionic liquid PPYILs with room temperature liquid-solid phase change characteristics, a rhodium catalyst, diphosphine ligands, a reaction substrate olefin and a reaction product aldehyde, a liquid/liquid two-phase hydroformylation reaction is performed at certain reaction temperature and under certain synthesis gas pressure, and the rhodium catalyst is recovered and cycled through simple two-phase separation after the reaction ends. The catalytic system has high catalytic activity, high selectivity, ultralong service life and very low rhodium catalyst loss amount, wherein the TOF value reaches 160-220 h; the area selectivity of normal aldehyde reaches 96%-98%; the catalytic cycle accumulated TON value is approximately 40,000; the rhodium catalyst loss amount is only 0.06%-0.2%.
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Paragraph 0025-0027; 0070-0072; 0079-0081
(2017/03/08)
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- Method of preparing normal aldehyde in highly selective manner through olefin two-phase hydroformylation on basis of phosphine functionalized polyether quaternary phosphorus salt ion liquid
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The invention relates to a method of preparing normal aldehyde in a highly selective manner through olefin two-phase hydroformylation on the basis of phosphine functionalized polyether pyrrolidine salt ion liquid. The method includes: adopting a two-phase catalysis system which is composed of phosphine functionalized polyether quaternary phosphorus salt ion liquid, rhodium catalyst, reaction substrate olefin and reaction product aldehyde; performing liquid/liquid two-phase hydroformylation at certain reaction temperature and synthetic gas pressure; after reaction is finished, separation and circulating the rhodium catalyst through simple two-phase separation, wherein the rhodium catalyst can be circulated for use for dozens of times without obviously lowering catalytic activity and selectivity. TOF value of the system reaches 300-2800 h, catalytic circulating accumulated TON value reaches 30856.
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Paragraph 0072-0074
(2017/03/14)
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- Method of preparing normal aldehyde in highly selective manner through olefin two-phase hydroformylation on basis of polyether piperidine salt ion liquid
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The invention relates to a method of preparing normal aldehyde in a highly selective manner through olefin two-phase hydroformylation on the basis of polyether piperidine salt ion liquid. The method includes: adopting a two-phase catalysis system which is composed of polyether piperidine salt ion liquid with room temperature liquid-solid phase transition characteristics, rhodium catalyst, diphosphine ligand, reaction substrate olefin and reaction product aldehyde; performing liquid/liquid two-phase hydroformylation at certain reaction temperature and synthetic gas pressure; after reaction is finished, recycling and circulating the rhodium catalyst through simple two-phase separation, wherein the rhodium catalyst can be circulated for use for dozens of times without obviously lowering catalytic activity and selectivity. TOF value of the system reaches 300-2400 h, catalytic circulating accumulated TON value reaches higher than 32489 to maximum extent, regioselectivity of the normal aldehyde is up to 96-98%, an rhodium loss is only 0.02-0.10%.
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Paragraph 0029; 0080-0082
(2017/04/11)
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- Method for highly selectively preparing normal aldehyde through alkene two-phase hydroformylation based on polyether pyrrolidine salt ion liquid
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The invention relates to a method for highly selectively preparing normal aldehyde through alkene two-phase hydroformylation based on polyether pyrrolidine salt ion liquid. A two-phase catalytic system is used herein and comprises polyether pyrrolidine salt ion liquid having indoor temperature liquid-solid phase change characteristics, a rhodium catalyst, diphosphine ligand, a reaction substrate alkene and a reaction product aldehyde; liquid/liquid two-phase hydroformylation is carried under certain reaction temperature and synthetic gas pressure, the rhodium catalyst is recycled through simple two-phase separation after reacting, the rhodium catalyst can be recycled tens of times, there is no significant decrease in catalytic activity and selectivity, TOF value of this system reaches 260-2000 h, catalytic circulatory accumulative TON value is up to higher than 34000, regioselectivity of the normal aldehyde is up to 96-98%, and rhodium loss is just 0.05-0.15%.
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Paragraph 0027; 0074; 0081-0083
(2017/06/02)
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- Method of preparing normal aldehyde in highly selective manner through olefin two-phase hydroformylation on basis of phosphine functionalized polyether pyrrolidine salt ion liquid
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The invention relates to a method of preparing normal aldehyde in a highly selective manner through olefin two-phase hydroformylation on the basis of phosphine functionalized polyether pyrrolidine salt ion liquid. The method includes: adopting a two-phase catalysis system which is composed of phosphine functionalized polyether pyrrolidine salt ion liquid, polyether pyrrolidine salt ion liquid, rhodium catalyst, reaction substrate olefin and reaction product aldehyde; performing liquid/liquid two-phase hydroformylation at certain reaction temperature and synthetic gas pressure; after reaction is finished, separation and circulating the rhodium catalyst through simple two-phase separation, wherein the rhodium catalyst can be circulated for use for dozens of times without obviously lowering catalytic activity and selectivity. TOF value of the system reaches 500-2700 h, catalytic circulating accumulated TON value reaches 32215.
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Paragraph 0051; 0075; 0076-0078
(2017/06/08)
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- Method for highly selectively preparing normal aldehyde through alkene two-phase hydroformylation based on phosphine functionalized polyether pyrrolidine salt ion liquid
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The invention relates to a method for highly selectively preparing normal aldehyde through alkene two-phase hydroformylation based on phosphine functionalized polyether pyrrolidine salt ion liquid. A two-phase catalytic system is used herein and comprises phosphine functionalized polyether pyrrolidine salt ion liquid, polyether pyrrolidine salt ion liquid, a rhodium catalyst, a reaction substrate alkene and a reaction product aldehyde; liquid/liquid two-phase hydroformylation is carried under certain reaction temperature and synthetic gas pressure, the rhodium catalyst is recycled through simple two-phase separation after reacting, the rhodium catalyst can be recycled multiple times, there is no significant decrease in catalytic activity and selectivity, TOF value of this system reaches 490-2900 h, catalytic circulatory accumulative TON value is up to higher than 33334.
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Paragraph 0051; 0076-0077
(2017/07/01)
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- Method for highly selective preparation of linear aldehyde by olefin two-phase hydroformylation based on phosphine functionalized polyether alkyl guanidine salt ionic liquid
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The invention relates to a method for highly selective preparation of linear aldehyde by olefin two-phase hydroformylation based on a phosphine functionalized polyether alkyl guanidine salt ionic liquid. The method adopts a two-phase catalytic system, the catalytic system is composed of the phosphine functionalized polyether alkyl guanidine salt ionic liquid, a polyether alkyl guanidine salt ionic liquid, a rhodium catalyst, a reaction substrate olefin and a reaction product aldehyde, liquid/liquid two-phase hydroformylation reaction is carried out under certain reaction temperature and synthesis gas pressure, simple two-phase separation is carried out at the end of the reaction to realize separation and circulation of the rhodium catalyst, the rhodium catalyst can be used repeatedly, and the catalytic activity and selectivity do not decrease significantly. The TOF value of the system reaches 300-3400h, and the catalytic cycle cumulative TON value reaches 30832.
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Paragraph 0079; 0080; 0081
(2017/01/02)
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- Method of preparing normal aldehyde in highly selective manner through olefin two-phase hydroformylation on basis of polyether morpholine salt ion liquid
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The invention relates to a method of preparing normal aldehyde in a highly selective manner through olefin two-phase hydroformylation on the basis of polyether morpholine salt ion liquid. The method includes: adopting a two-phase catalysis system which is composed of polyether morpholine salt ion liquid with room temperature liquid-solid phase transition characteristics, rhodium catalyst, diphosphine ligand, reaction substrate olefin and reaction product aldehyde; performing liquid/liquid two-phase hydroformylation at certain reaction temperature and synthetic gas pressure; after reaction is finished, recycling and circulating the rhodium catalyst through simple two-phase separation, wherein the rhodium catalyst can be circulated for use for dozens of times without obviously lowering catalytic activity and selectivity. TOF value of the system reaches 260-2000 h-1, catalytic circulating accumulated TON value reaches higher than 35000 to maximum extent, regioselectivity of the normal aldehyde is up to 96-98%, an rhodium loss is only 0.01-0.10%.
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Paragraph 0025-0027; 0082-0084
(2017/06/24)
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- From alkenes to alcohols by cobalt-catalyzed hydroformylation-reduction
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The cobalt-catalyzed hydroformylation of alkenes in the presence of a range of novel cyclic phosphine ligands was investigated. The effect of various parameters such as solvents, additives, cobalt/phosphine ratio, CO/H2 (1:2), and nature of the alkenes was examined. The results revealed that both terminal and internal alkenes are hydroformylated in high yields to give mainly linear products at moderate temperature and syn gas pressure. The linearity ranges from 43 to 85%, with Lim-10 giving the highest proportion of linear product.
- Achonduh, George,Yang, Qian,Alper, Howard
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supporting information
p. 1241 - 1246
(2015/03/05)
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- Oxidation of plasmalogen, low-density lipoprotein and raw 264.7 cells by photoactivatable atomic oxygen precursors
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The oxidation of lipids by endogenous or environmental reactive oxygen species (ROS) generates a myriad of different lipid oxidation products that have important roles in disease pathology. The lipid oxidation products obtained in these reactions are dependent upon the identity of the reacting ROS. The photoinduced deoxygenation of various aromatic heterocyclic oxides has been suggested to generate ground state atomic oxygen (O[3P]) as an oxidant; however, very little is known about reactions between lipids and O(3P). To identify lipid oxidation products arising from the reaction of lipids with O(3P), photoactivatable precursors of O( 3P) were irradiated in the presence of lysoplasmenylcholine, low-density lipoprotein and RAW 264.7 cells under aerobic and anaerobic conditions. Four different aldehyde products consistent with the oxidation of plasmalogens were observed. The four aldehydes were: tetradecanal, pentadecanal, 2-hexadecenal and hexadecanal. Depending upon the conditions, either pentadecanal or 2-hexadecenal was the major product. Increased amounts of the aldehyde products were observed in aerobic conditions. The photodeoxygenation of dibenzothiophene S-oxide has been suggested to generate ground state atomic oxygen (O[3P]). The reactivity of the putative O(3P) is distinct from other reactive oxygen species (ROS) and little is known about its reactivity with lipids and other biomolecules. In this work, exposure of low-density lipoprotein (LDL) to O(3P) yielded four aldehyde products. The same aldehydes were observed after the oxidation of an isolated plasmalogen by O(3P).
- Bourdillon, Max T.,Ford, Benjamin A.,Knulty, Ashley T.,Gray, Colleen N.,Zhang, Miao,Ford, David A.,McCulla, Ryan D.
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p. 386 - 393
(2014/04/03)
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- Synergetic effect of randomly methylated β-cyclodextrin and a supramolecular hydrogel in Rh-catalyzed hydroformylation of higher olefins
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A significant improvement in Rh-catalyzed hydroformylation of very hydrophobic alkenes was achieved using a biphasic catalytic system consisting of a substrate-containing organic phase and a catalyst-containing hydrogel phase [consisting of poly(ethylene glycol) 20000 (PEG20000) and α-cyclodextrin (α-CD)]. The catalytic performance of the Pickering emulsion that resulted from the formation of α-CD/PEG20000 crystallites at the oil droplet surface proved to be greatly dependent upon the presence of additives. We showed that controlled uploads of randomly methylated β-cyclodextrin (RAME-β-CD) within the supramolecular hydrogel could positively affect both the catalytic activity and chemoselectivity of the hydroformylation reaction. Conversely, no Pickering emulsion could be observed using excess RAME-β-CD, resulting in the subsequent degradation of the catalytic performance. Optical microscopy and optical fluorescence microscopy supported the catalytic results and allowed us to explain the role of RAME-β-CD. Indeed, controlled uploads of RAME-β-CD prevented the saturation of the oil droplet surface. RAME-β-CD acted as a fluidifier of the Pickering emulsion and accelerated the dynamics of exchange between the substrate-containing organic phase and the catalyst-containing hydrogel phase. Morever, RAME-β-CD acted as a receptor that participated in the conversion of the alkene by supramolecular means.
- Potier, Jonathan,Menuel, Stephane,Monflier, Eric,Hapiot, Frederic
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p. 2342 - 2346
(2014/07/21)
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- Probing the mechanism of cyanobacterial aldehyde decarbonylase using a cyclopropyl aldehyde
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Cyanobacterial aldehyde decarbonylase (cAD) is a non-heme diiron oxygenase that catalyzes the conversion of fatty aldehydes to alkanes and formate. The mechanism of this chemically unusual reaction is poorly understood. We have investigated the mechanism of C1-C2 bond cleavage by cAD using a fatty aldehyde that incorporates a cyclopropyl group, which can act as a radical clock. When reacted with cAD, the cyclopropyl aldehyde produces 1-octadecene as the rearranged product, providing evidence for a radical mechanism for C-C bond scission. In an alternate pathway, the cyclopropyl aldehyde acts as a mechanism-based irreversible inhibitor of cAD through covalent binding of the alkyl chain to the enzyme.
- Paul, Bishwajit,Das, Debasis,Ellington, Benjamin,Marsh, E. Neil G.
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supporting information
p. 5234 - 5237
(2013/05/22)
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- Pickering emulsions based on supramolecular hydrogels: Application to higher olefins' hydroformylation
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Supramolecular hydrogels elaborated from a mixture of native α-cyclodextrin and poly(ethylene glycol)s in water proved to be effective media for higher olefins Rh-catalyzed hydroformylation due to the formation of Pickering emulsions.
- Potier, Jonathan,Menuel, Stephane,Chambrier, Marie-Heleine,Burylo, Laurence,Blach, Jean-Francois,Woisel, Patrice,Monflier, Eric,Hapiot, Frederic
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p. 1618 - 1621
(2013/07/26)
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- Total synthesis of (-)-goniotrionin
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A stereoselective total synthesis of the reported structure of goniotrionin (4) has been accomplished. The key steps involved the opening of a chiral epoxide, a highly diastereoselective Mukaiyama aerobic oxidative cyclization, a selective 1,2-syn Mukaiyama aldol reaction, and a Noyori reduction.
- Dias, Luiz C.,Ferreira, Marco A. B.
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experimental part
p. 4046 - 4062
(2012/06/29)
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- Cyclodysidins A-D, cyclic lipopeptides from the marine sponge-derived Streptomyces strain RV15
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Four new cyclic lipopeptides, cyclo-(AFA-Ser-Gln-Asn-Tyr-Asn-Ser-Thr), named cyclodysidins A-D, were isolated from the broth culture of Streptomyces strain RV15 associated with the marine sponge Dysidea tupha. The sequences of the amino acid building blocks in the compounds and their structures were determined by 1D- and 2D-NMR techniques and CID-MS/MS experiments. The absolute configurations of all α-amino acids were determined by HPLC analysis after derivatization with Marfey's reagent and comparison with commercially available reference samples, while those two of the β-amino fatty acids were determined by using racemic and enantiopure reference samples synthetically prepared.
- Abdelmohsen, Usama Ramadan,Zhang, Guoliang,Philippe, Allan,Schmitz, Werner,Pimentel-Elardo, Sheila Marie,Hertlein-Amslinger, Barbara,Hentschel, Ute,Bringmann, Gerhard
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body text
p. 23 - 29
(2012/01/17)
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- Rh nanoparticles catalyzed hydroformylation of olefins in a thermoregulated ionic liquid/organic biphasic system
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Rh nanoparticles were investigated as a catalyst for hydroformylation of olefins in thermoregulated ionic liquid/organic biphasic systems composed of an ionic liquid, namely [CH3(OCH2CH2) 16N+Et3][CH3SO3 -] (ILPEG750), and an organic solvent. This enables not only a homogeneous reaction but also easy biphasic separation. Under the optimized reaction conditions, the conversion of 1-octene and yield of aldehyde were 99 and 91, respectively. The catalyst was easily separated from the product by phase separation and used eight times without evident loss of activity.
- Zeng, Yan,Wang, Yanhua,Xu, Yicheng,Song, Ying,Zhao, Jiaqi,Jiang, Jingyang,Jin, Zilin
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scheme or table
p. 402 - 406
(2012/07/14)
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- Aqueous biphasic hydroformylation in the presence of cyclodextrins mixtures: Evidence of a positive synergistic effect
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Mixtures of randomly methylated cyclodextrins of various sizes have been evaluated in the rhodium-catalysed hydroformylation of higher olefins in an aqueous biphasic medium. A marked positive non-linear effect on 1-tetradecene conversion is observed when the CD molar ratio in the mixture is modified. The formation of 2:1 ternary inclusion complexes between RAME-CDs and the olefin is supposed to be responsible for the extra conversion observed. The Royal Society of Chemistry.
- Ferreira, Michel,Legrand, Francois-Xavier,MacHut, Cecile,Bricout, Herve,Tilloy, Sebastien,Monflier, Eric
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experimental part
p. 8643 - 8647
(2012/10/08)
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- Super long-term highly active and selective hydroformylation in a room temperature-solidifiable guanidinium ionic liquid with a polyether tag
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Here we report a novel room temperature-solidifiable guanidinium methanesulfonate with a polyether tag and its use in Rh-catalysed biphasic hydroformylation of higher olefins. This novel ionic liquid can efficiently immobilize the Rh-TPPTS catalyst and render super long-term high activity and chemoselectivity, and no significant loss of activity, selectivity or Rh was observed after thirty-five cycles.
- Jin, Xin,Yang, Daoxing,Xu, Xinfu,Yang, Zhiqiang
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supporting information
p. 9017 - 9019,3
(2020/08/31)
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- Modulation of the activity of histone acetyltransferases by long chain alkylidenemalonates (LoCAMs)
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A novel class of KAT modulators (long chain alkylidenemalonates, LoCAMs) has been identified. Variations of the alkyl chain length can change the activity profile from inhibition of both KAT3A/KAT2B (as derivative 2a) to the peculiar profile of pentadecylidenemalonate 1b, the first activator/inhibitor of histone acetyltransferases. Together with the powerful apoptotic effect (particularly notable if considering that anacardic acid and other KAT inhibitors are not cell permeable) appoint them as valuable biological tools to understand the mechanisms of lysine acetyltransferases.
- Milite, Ciro,Castellano, Sabrina,Benedetti, Rosaria,Tosco, Alessandra,Ciliberti, Carmen,Vicidomini, Caterina,Boully, Ludovic,Franci, Gianluigi,Altucci, Lucia,Mai, Antonello,Sbardella, Gianluca
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experimental part
p. 3690 - 3701
(2011/08/03)
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- Two new fatty acid derivatives from the stem bark of alchornea laxiflora (euphorbiaceae)
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Euphorbiaceae is a family of plants used in traditional remedies in central Africa to treat selected diseases. Some of the phytochemical components in the stem bark of Alchornea laxiflora that have biochemical activity were identified. A number of novel compounds were isolated, including a new fatty acid ester, (1) a new ceramide, (2) some triterpenoids, (3-5), ellagic acid (6) and its derivatives (7, 8) were isolated. The structures of these compounds were determined on the basis of spectroscopic methods as well as HR-ESI-TOF-MS analysis, chemical transformation and by comparison of their physical and spectral data with those reported in the literature. The cytotoxicity of some isolated compounds was investigated against human promyelocytic leukaemia (HL60) cell line by using the MTT method. Compounds 1, 4 and 5 showed a cytotoxic activity with IC50 at 58.7, 6.6 and 6.8 μM, respectively.
- Sandjo, Louis Pergaud,Poumale, Hervé M. Poumale,Siwe, Xavier Noudou,Ntede, Hippolyte Nga,Shiono, Yoshihito,Ngadjui, Bonaventure Tchaleu,Krause, Rui M. W.,Ndinteh, Derek Tantoh,Mbafor, Joseph Tanyi
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p. 1153 - 1159
(2011/11/12)
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- Catalytic mechanism of a heme and tyrosyl radical-containing fatty acid α-(di)oxygenase
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The steady-state catalytic mechanism of a fatty acid α-(di)oxygenase is examined, revealing that a persistent tyrosyl radical (Tyr379 ?) effects O2 insertion into Cα-H bonds of fatty acids. The initiating Cα-H homolysis step is characterized by apparent rate constants and deuterium kinetic isotope effects (KIEs) that increase hyperbolically upon raising the concentration of O 2. These results are consistent with H? tunneling, transitioning from a reversible to an irreversible regime. The limiting deuterium KIEs increase from ～30 to 120 as the fatty acid chain is shortened from that of the native substrate. In addition, activation barriers increase in a manner that reflects decreased fatty acid binding affinities. Anaerobic isotope exchange experiments provide compelling evidence that Tyr379 ? initiates catalysis by H? abstraction. C α-H homolysis is kinetically driven by O2 trapping of the α-carbon radical and reduction of a putative peroxyl radical intermediate to a 2(R)-hydroperoxide product. These findings add to a body of work which establishes large-scale hydrogen tunneling in proteins. This particular example is novel because it involves a protein-derived amino acid radical.
- Mukherjee, Arnab,Angeles-Boza, Alfredo M.,Huff, Gregory S.,Roth, Justine P.
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experimental part
p. 227 - 238
(2011/03/16)
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- A short enantioselective synthesis of guggultetrol, a naturally occurring lipid
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An enantioselective synthesis of the naturally occurring lipid, guggultetrol, is described with an overall yield of 24% starting from commercially available l-pentadecanol in ten linear steps. The key chiral-inducing steps include a Sharpless asymmetric epoxidation of allylic alcohol and a dihydroxylation of an α,β-unsaturated ester.
- George, Shyla,Suryavanshi, Gurunath,Sudalai, Arumugam
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experimental part
p. 558 - 561
(2010/08/06)
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- A general and concise asymmetric synthesis of sphingosine, safingol and phytosphingosines via tethered aminohydroxylation
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A novel, practical and efficient enantioselective synthesis of sphingoid bases, l-threo-[2S,3S]-sphinganine (safingol), l-threo-[2S,3S]-sphingosine, l-arabino-[2R,3S,4R] and l-xylo-[2R,3S,4S]-C18-phytosphingosine is described. The synthetic strategy features the Sharpless kinetic resolution and tethered aminohydroxylation (TA) as the key steps.
- Kumar, Pradeep,Dubey, Abhishek,Puranik, Vedavati G.
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experimental part
p. 5074 - 5086
(2010/12/25)
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- Metathesis reactions of β-acyloxysulfones: synthesis of 1,6- and 1,7-dienes
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A novel alkene-masking strategy has been developed that allows for a metathesis approach to 1,6- and 1,7-dienes. This method was successfully applied to the synthesis of a long-chain alkenone natural product.
- O'Neil, Gregory W.,Moser, Daniel J.,Volz, Erasmus O.
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supporting information; experimental part
p. 7355 - 7357
(2010/03/01)
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- A tethered aminohydroxylation route to l-arabino-[2R,3S,4R] and l-xylo-[2R,3S,4S]-C18-phytosphingosines
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A concise and highly efficient synthesis of l-arabino-[2R,3S,4R] and l-xylo-[2R,3S,4S]-C18-phytosphingosines has been achieved. The synthetic strategy features the Sharpless kinetic resolution and tethered aminohydroxylation as the key steps.
- Dubey, Abhishek,Kumar, Pradeep
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scheme or table
p. 3425 - 3427
(2009/09/06)
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- Identification of long chain alkylidenemalonates as novel small molecule modulators of histone acetyltransferases
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Pentadecylidenemalonate 1b, a simplified analogue of anacardic acid, was identified as the first mixed activator/inhibitor of histone acetyltransferases (HATs). It potentiates PCAF HAT activity while inhibiting those of p300/CBP and recombinant CBP. The remarkable apoptotic effect together with the ability to selectively acetylate histone versus non-histone substrates appoint 1b as a lead for the development of anticancer drugs.
- Sbardella, Gianluca,Castellano, Sabrina,Vicidomini, Caterina,Rotili, Dante,Nebbioso, Angela,Miceli, Marco,Altucci, Lucia,Mai, Antonello
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p. 2788 - 2792
(2008/12/23)
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- A novel stereoselective synthesis of pachastrissamine (jaspine B) starting from 1-pentadecanol
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A novel stereoselective synthesis of pachastrissamine (jaspine B), starting from commercially available 1-pentadecanol is described. Sharpless asymmetric dihydroxylation and a chelation controlled vinyl Grignard reaction are the key steps in this synthetic strategy.
- Venkatesan,Srinivasan
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p. 209 - 215
(2008/09/19)
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- Binuclear ruthenium(III) Schiff base complexes bearing N4O4 donors and their catalytic oxidation of alcohols
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An interesting series of binuclear ruthenium(III) Schiff base complexes bearing bis-salophen/bis-naphophen units of the general composition [(EPh3)(X)Ru-L-Ru(X)(EPh3)] (where E = P or As; X = Cl or Br; L = binucleating dianionic tetradentate ligands) have been synthesized and characterized by analytical (elemental analysis, magnetic susceptibility measurements), spectral (FT-IR, UV-vis and EPR) and electrochemical methods. These ruthenium(III) complexes have two N2O2 metal binding sites, which are linked to each other with a biphenyl bridge and acts as potential catalyst for oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO). The formation of high-valent RuV = O species as a catalytic active intermediate is proposed for the catalytic processes.
- Venkatachalam,Raja,Pandiarajan,Ramesh
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experimental part
p. 884 - 891
(2009/02/06)
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- Aldehydes substituted in alpha position by alkyl residues as odoriferous and aroma substances
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The present invention primarily relates to the use of an aldehyde, substituted in alpha position by an alkyl residue, of the formula having (I) a total of 13 C atoms, wherein R means an unbranched alkyl residue having 6, 7, 8 or 9 C atomsandR′ means an unbranched alkyl residue having 2, 3, 4 or 5 C atoms, or (II) a total of 15 C atoms, wherein R means an unbranched alkyl residue having 8, 9, 10 or 11 C atomsandR′ means an unbranched alkyl residue having 2, 3, 4 or 5 C atoms,or a blend comprising or consisting of two, three or more such aldehydes of type (I) and/or (II),as an odoriferous or aroma substance.
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Page/Page column 10
(2010/11/29)
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- Structural confirmation of the dihydrosphinganine and fatty acid constituents of the dental pathogen Porphyromonas gingivalis
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Porphyromonas gingivalis, a recognized periodontal pathogen, is a source of sphinganine bases, fatty acids, free ceramides as well as complex lipids that potentiate interleukin-1b-mediated secretory responses in gingival fibroblasts. The purpose of this study is the structural verification of the sphinganine bases and fatty acids that had been proposed as major components of the complex lipids found in P. gingivalis. The putative C17, C18, and C19 sphinganine bases were prepared from Garner's aldehyde (1) or from a protected serine Weinreb's amide (2). We confirmed that isobranched sphinganine bases are the major structural feature of the ceramides observed from P. gingivalis. We also prepared a C17 unsaturated fatty acid, along with an isobranched C17 3-hydroxy fatty acid, and determined that the major component of the active lipids was the latter. The Royal Society of Chemistry 2007.
- Mun, JiYoung,Onorato, Amber,Nichols, Frank C.,Morton, Martha D.,Saleh, Abdullah I.,Welzel, Morgan,Smith, Michael B.
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p. 3826 - 3833
(2008/10/09)
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- Sensory-directed identification of creaminess-enhancing volatiles and semivolatiles in full-fat cream
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Aimed at defining the chemical nature of creaminess-related flavor compounds in dairy products on a molecular level, a full-fat cream was analyzed for sensorially active volatiles and semivolatiles by means of activity-guided screening techniques. Application of the aroma extract dilution analysis on an aroma distillate prepared from pasteurized cream (30% fat) revealed δ-decalactone, (Z)-6-dodeceno-γ-lactone, γ-dodecalactone, δ-dodecalactone, and 3-methylindole with by far the highest flavor dilution (FD) factors among the 34 odor-active volatiles identified. Using a complementary approach involving silica column chromatography and fractionated high-vacuum distillation combined with sensory experiments enabled the additional identification of δ-tetradecalactone, δ-hexadecalactone, γ-tetradecalactone, γ-hexadecalactone, and δ-octadecalactone as semivolatile flavor components in the cream fat. Although a series of lactones is present in dairy cream, spiking of cream samples with individual lactones revealed that only the δ-tetradecalactone is able to enhance the typical retronasal creamy flavor of the product when added in amounts above its theshold level of 66 μmol/kg. Rather than contributing to the retronasal aroma of cream, first evidence was found that, particularly, γ- and δ-octadecalactones and γ- and δ-eicosalactones are able to influence the melting behavior of cream in the oral cavity.
- Schlutt, Birgit,Moran, Noelia,Schieberle, Peter,Hofmann, Thomas
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p. 9634 - 9645
(2008/03/17)
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- An efficient conversion of carboxylic acids to one-carbon degraded aldehydes via 2-hydroperoxy acids
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After the formation of dianions of a carboxylic acid with lithium diisopropylamide, oxygen was bubbled into the solution to produce 2-hydroperoxy acid. Then the reaction mixture was acidified with a 2N HCl solution and subsequently elevated to 50°C to afford the aldehyde with the loss of one carbon atom. Even saturated (C10-C20) and unsaturated (C18:1) carboxylic acids were converted into the odd aldehydes (C9-C19, C17:1) in high yields. This conversion was found to be an efficient method for the preparation of carboxylic acids (Cn) to one-carbon degraded aldehydes (Cn-1) via 2-hydroperoxy acids.
- Akakabe, Yoshihiko,Nyuugaku, Takeshi
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p. 1370 - 1371
(2008/02/07)
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- Tyrosine-selective protein alkylation using π-allylpalladium complexes
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A new protein modification reaction has been developed based on a palladium-catalyzed allylic alkylation of tyrosine residues. This technique employs electrophilic π-allyl intermediates derived from allylic acetate and carbamate precursors and can be used to modify proteins in aqueous solution at room temperature. To facilitate the detection of modified proteins using SDS-PAGE analysis, a fluorescent allyl acetate was synthesized and coupled to chymotrypsinogen A and bacteriophage MS2. The tyrosine selectivity of the reaction was confirmed through trypsin digest analysis. The utility of the reaction was demonstrated by using taurine-derived carbamates as water solubilizing groups that are cleaved upon protein functionalization. This solubility switching technique was used to install hydrophobic farnesyl and C17 chains on chymotrypsinogen A in water using little or no cosolvent. Following this, the C17 alkylated proteins were found to associate with lipid vesicles. In addition to providing a new protein modification strategy targeting an under-utilized amino acid side chain, this method provides convenient access to synthetic lipoproteins. Copyright
- Tilley, S. David,Francis, Matthew B.
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p. 1080 - 1081
(2007/10/03)
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- Oxidative photo-decarboxylation in the presence of mesoporous silicas
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FSM-16, a mesoporous silica, was found to catalyze oxidative photo-decarboxylation of α-hydroxy carboxylic acid, phenyl acetic acid derivatives and N-acyl-protected α-amino acids to afford the corresponding carbonyl compounds. Furthermore, FSM-16 proved to be re-usable by re-calcination at 450°C after the reaction.
- Itoh, Akichika,Kodama, Tomohiro,Masaki, Yukio,Inagaki, Shinji
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p. 1571 - 1575
(2007/10/03)
-
- First total synthesis of the irciniasulfonic acids
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A flexible and concise first total synthesis of the irciniasulfonic acids is reported.
- Dobbs, Adrian P.,Venturelli, Alberto,Butler, Laura A.,Parker, Robert J.
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p. 652 - 654
(2007/10/03)
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- Stereoselective synthesis of the antiprotozoal lactone passifloricin A and seven isomers thereof
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The conjugated δ-lactone passifloricin A, a natural product with antiprotozoal activity, and seven isomers thereof have been synthesized in enantiopure form. It has been shown in this way that the proposed structure for the natural compound was erroneous. The correct structure is now evidenced. Key steps of the syntheses were asymmetric Brown-type aldehyde allylations and ring-closing metatheses.
- Murga, Juan,Garcia-Fortanet, Jorge,Carda, Miguel,Marco, J. Alberto
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p. 7277 - 7283
(2007/10/03)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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