Xi:Irritant;
106-22-9Relevant academic research and scientific papers
Electrochemical hydrogenation of citral 1. The role of the copper cathode in the electroreduction of citral
Korotyaeva, L. M.,Rubinskaya, T. Ya.,Gultyai, V. P.
, p. 1830 - 1834 (1993)
Alcohols (citronellol and isomeric nerol and geraniol) are the main products of the electroreduction of citral at the copper cathode in the presence in the AcOH in a water-DMF medium.It has been suggested that under the conditions of the electrolysis at the hydrogen reduction potential (E = -1.2 V) electroreduction of citral occurs according to the electrochemical hydrogenation mechanism.The total yield of the alcohols and the selectivity of the process depend on the preliminary treatment of the cathode.The electroreduction of citral at a mechanically cleaned cathode gives alcohols in 54percent total yield, and unsaturated alcohols are the prevailing products.Preliminary annealing of the cathode results in an increase in the total yield of alcohols in the electrolysis to 86percent and in the predominant formation of citronellol. - Key words: copper cathode, citral, citronellol, electrochemical hydrogenation, electroreduction, recrystallization.
Bis(phosphine)cobalt dialkyl complexes for directed catalytic alkene hydrogenation
Friedfeld, Max R.,Margulieux, Grant W.,Schaefer, Brian A.,Chirik, Paul J.
, p. 13178 - 13181 (2014)
Planar, low-spin cobalt(II) dialkyl complexes bearing bidentate phosphine ligands, (P - P)Co-(CH2SiMe3)2, are active for the hydrogenation of geminal and 1,2-disubstituted alkenes. Hydrogenation of more hindered internal and endocyclic trisubstituted alkenes was achieved through hydroxyl group activation, an approach that also enables directed hydrogenations to yield contrasteric isomers of cyclic alkanes.
Chemoselective Hydrogenation of Aldehydes under Mild, Base-Free Conditions: Manganese Outperforms Rhenium
Glatz, Mathias,St?ger, Berthold,Himmelbauer, Daniel,Veiros, Luis F.,Kirchner, Karl
, p. 4009 - 4016 (2018)
Several hydride Mn(I) and Re(I) PNP pincer complexes were applied as catalysts for the homogeneous chemoselective hydrogenation of aldehydes. Among these, [Mn(PNP-iPr)(CO)2(H)] was found to be one of the most efficient base metal catalysts for this process and represents a rare example which permits the selective hydrogenation of aldehydes in the presence of ketones and other reducible functionalities, such as C=C double bonds, esters, or nitriles. The reaction proceeds at room temperature under base-free conditions with catalyst loadings between 0.1 and 0.05 mol% and a hydrogen pressure of 50 bar (reaching TONs of up to 2000). A mechanism which involves an outer-sphere hydride transfer and reversible PNP ligand deprotonation/protonation is proposed. Analogous isoelectronic and isostructural Re(I) complexes were only poorly active.
Homogeneous electro-mediated reduction of unsaturated compounds using Ni and Fe as mediators in DMF
da Silva, Aderivaldo P.,Mota, Saulo D.C.,Bieber, Lothar W.,Navarro, Marcelo
, p. 5435 - 5440 (2006)
The homogeneous electro-mediated reduction (HEMR) of several organic compounds (cyclohexene, cyclohexanone, acetophenone, benzaldehyde, styrene, linalool, 1,3-cyclohexadiene, citral, trans-4-phenyl-3-buten-2-one, and piperine) was carried out using Fe2+, Ni2+, and [NiII(bpy)]Br2 (bpy=2,2′-bipyridine) as electron mediators. An electrochemical system composed of sacrificial anode (Fe, Ni or Zn), nickel cathode, NaI (0.2 M) as supporting electrolyte in DMF and an undivided cell, was used. A constant current ≤100 mA was applied with a maximum cell potential of 2.0 V. Non-conjugated olefins are not reactive, but ketones may be easily reduced to the respective alcohol. In the case of conjugated olefins and ketones, [NiII(bpy)]Br2 or Ni2+ mediator presented good reactivity and selectivity in most cases. Fe2+ more efficiently mediates the reduction of carbonyl containing systems. Preliminary electroanalytical studies indicate the complexation of the organic substrate by Fe2+ and Ni2+ ions and [NiII(bpy)]Br2 complex.
Hydrogenation of alkenes with rhodium nanoparticles supported on SBA-15
Bhorali, Nayanmoni,Ganguli, Jatindra Nath
, p. 276 - 281 (2013)
Rhodium nanoparticles were prepared by chemical reduction of RhCl 3·3H2O in presence of polyvinyl pyrrolidone and then immobilized on SBA-15 by impregnation. The catalyst was used for hydrogenation of unsaturated hydrocarbons at room temperature. The progress of the reaction was monitored by GC-MS and 100 % conversion was achieved in all cases.
Biphasic reduction of unsaturated aldehydes to unsaturated alcohols by ruthenium complex-catalyzed hydrogen transfer
Joo, Ferenc,Benyei, Attila
, p. C19 - C21 (1989)
Unsaturated aldehydes can be reduced under very mild conditions (30-80 deg C) with good yields and excellent selcetivities to the corresponding unsaturated alcohols by hydrogen transfer from HCOONa/H2O catalyzed by a complex of RuII with sulphonated triphenylphosphine in aqueous/organic biphasic systems.
Reduction of carbonyl compounds by using polymethylhydrosiloxane: Reactivity and selectivity
Kobayashi, Yuichi,Takahisa, Eisuke,Nakano, Miwa,Watatani, Kengo
, p. 1627 - 1634 (1997)
Reduction of aldehydes and ketones with PMHS [Me3SiO-(SiMe(H)O)(n)-SiMe3] proceeded smoothly in the presence of Bu4NF at -70°C or 0°C within 60 min in THF. High stereo- and chemoselectivities as well as functional group tolerance of this system are also presented.
Effect of 2-propanol on the transfer hydrogenation of aldehydes by aqueous sodium formate using a rhodium(i)-sulfonated triphenylphosphine catalyst
Kathó, ágnes,Szatmári, Imre,Papp, Gábor,Joó, Ferenc
, p. 339 - 344 (2015)
In water/2-propanol mixtures [RhCl(mtppms)3] (mtppms = monosulfonated triphenylphosphine) was an efficient catalyst for the selective C=C reduction of trans-3-phenyl-2-propenal (trans-cinnamaldehyde) by hydrogen transfer from formate at temperatures as low as 30 °C. An outstandingly high catalyst turnover frequency of 1214 h-1 was determined at 70 °C. A possible mechanism of the reaction is suggested on the basis of kinetic studies and 1H- and 31P-NMR spectroscopic identification of the major Rh(i) species in the reaction mixtures as cis-mer-[H2RhX(mtppms)3] (X = HCOO- or H2O). It was established that a large part but not all of the rate increase observed in water/2-propanol mixtures in comparison with systems with neat water as solvent was the consequence of complete dissolution of trans-cinnamaldehyde on the effect of the co-solvent. Nevertheless, the rate showed a significant further increase with increasing 2-propanol concentration even in homogeneous solution and this was ascribed to changes in the solvent structure. The high catalyst activity in this solvent mixture allowed the transfer hydrogenation of citral. Although good to excellent conversions were observed at 30-70 °C, a useful degree of selectivity in hydrogenation of C=C vs. C=O bonds could not be achieved.
Hydrogenation of aldehydes and ketones to corresponding alcohols with methylamine borane in neat water
Duan, Yifan,Bai, Ruijiao,Tian, Jun,Chen, Ligong,Yan, Xilong
, p. 2555 - 2564 (2014)
GRAPHICAL ABSTRACT Chemoselective hydrogenation of various aldehydes and ketones with methylamine borane (MeAB) in neat water was investigated. MeAB is suitable for green organic reactions, for MeAB is a nontoxic, environmentally benign, and easily handled reagent. Aldehydes were selectively and rapidly hydrogenated in excellent yields (86-97%) for 30 min, but hydrogenation of aromatic ketones needed over 20 h at room temperature because of their poor water solubility and steric hindrance. Thus we investigated polyethylene glycol (PEG400) and acidic cation-exchange D072 resin as catalysts to accelerate the hydrogenation reaction of aromatic ketones and achieved excellent yields within several hours. PEG 400 and D072 resin are both suitable for green organic reactions. The D072 resin was reused up to four times without any significance loss in activity.
Synthesis, crystal structure, and catalytic properties of MgCo 6Ge6
Gieck, Christine,Schreyer, Martin,Faessler, Thomas F.,Cavet, Sylwia,Claus, Peter
, p. 1924 - 1930 (2006)
The ternary compound MgCo6Ge6 represents a novel member of the RM6X6 phases, which contains a graphite-type Ge network, Kagome nets of Co atoms, and Ge2 dumbbells with an unexpected short Ge-Ge contact in the range of a localized Ge-Ge single bond. The title compound shows a large variety of chemical bonding, which ranges from metallic to multi-center and covalent bonding. The role of polar intermetallic alloys as promising candidates for the application as catalysts for the selective hydrogenation of α,β-unsaturated aldehydes is discussed. MgCo6Ge6 possesses a remarkable activity and selectivity for the hydrogenation of cis/trans-citral to geraniol and nerol.
