100-55-0Relevant articles and documents
Mild Selective Deoxygenation of Amine Oxides by Tin-Tin Bonded Derivatives
Jousseaume, Bernard,Chanson, Evelyne
, p. 55 - 56 (1987)
A new method of deoxygenation of amine oxides with tin reagent is proposed.It utilizes the reductive properties of the tin-tin bond in hexabutyldistannane or 1,2-dichlorotetrabutyldistannane.Oxides of tertiary amines are reduced into amines by hexabutyldistannane in high yields, whereas pyridine N-oxides react cleanly with 1,2-dichlorotetrabutyldistannane to give the corresponding pyridines.These reactions occur under mild conditions and are very selective.
Hydrolysis of nicotinyl 6-aminonicotinate
Wang,Patel
, p. 204 - 207 (1986)
The degradation kinetics of nicotinyl 6-aminonicotinate in aqueous buffer solutions were studied over the pH range from 4.0 to 10.0. In all cases, pseudo-first-order kinetics were observed at constant hydronium ion concentration. The pH-rate profile indic
Mild and selective reduction of aldehydes utilising sodium dithionite under flow conditions
Neyt, Nicole C.,Riley, Darren L.
, p. 1529 - 1536 (2018)
We recently reported a novel hybrid batch-flow synthesis of the antipsychotic drug clozapine in which the reduction of a nitroaryl group is described under flow conditions using sodium dithionite. We now report the expansion of this method to include the reduction of aldehydes. The method developed affords yields which are comparable to those under batch conditions, has a reduced reaction time and improved space-time productivity. Furthermore, the approach allows the selective reduction of aldehydes in the presence of ketones and has been demonstrated as a continuous process.
Towards practical earth abundant reduction catalysis: Design of improved catalysts for manganese catalysed hydrogenation
Widegren, Magnus B.,Clarke, Matthew L.
, p. 6047 - 6058 (2019)
Manganese catalysts derived from tridentate P,N,N ligands can be activated easily using weak bases for both ketone and ester hydrogenations. Kinetic studies indicate the ketone hydrogenations are 0th order in acetophenone, positive order in hydrogen and 1st order in the catalyst. This implies that the rate determining step of the reaction was the activation of hydrogen. New ligand systems with varying donor strength were studied and it was possible to make the hydrogen activation significantly more efficient; a catalyst displaying around a 3-fold increase in initial turn-over frequencies for the hydrogenation of acetophenone relative to the parent system was discovered as a result of these kinetic investigations. Ester hydrogenations and ketone transfer hydrogenation (isopropanol as reductant) are first order for both the substrate and catalysts. Kinetic studies also gained insight into catalyst stability and identified a working range in which the catalyst is stable throughout the catalytic reaction (and a larger working range where high yields can still be achieved). The new more active catalyst, combining an electron-rich phosphine with an electron-rich pyridine is capable of hydrogenating acetophenone using as little as 0.01 mol% catalyst at 65 °C. In all, protocols for reduction of 21 ketones and 15 esters are described.
REDUCTION WITH POLYMER-BOUND NADH MODELS.
Dupas, G.,Bourguignon, J.,Ruffin, C.,Queguiner, G.
, p. 5141 - 5144 (1982)
We have performed numerous reductions with a NADH model grafted on a Merrifield resin.The yields are generally excellent and in all cases always superior to those obtained with "free" models.
Air-stable gold nanoparticles ligated by secondary phosphine oxides for the chemoselective hydrogenation of aldehydes: Crucial role of the ligand
Cano, Israel,Chapman, Andrew M.,Urakawa, Atsushi,Van Leeuwen, Piet W. N. M.
, p. 2520 - 2528 (2014)
The synthesis of air-stable and homogeneous gold nanoparticles (AuNPs) employing tert-butyl(naphthalen-1-yl)phosphine oxide as supporting ligand is described via NaBH4 reduction of a Au(I) precursor, [(tert-butyl(naphthalen-1-yl)phosphine oxide)AuCl]2. This highly reproducible and simple procedure furnishes small (1.24 ± 0.16 nm), highly soluble nanoparticles that are found to be highly active catalysts for the hydrogenation of substituted aldehydes, giving high conversions and chemoselectivities for a wide variety of substrates. In addition to catalytic studies the role of the novel stabilizer in the remarkable activity and selectivity exhibited by this system was interrogated thoroughly using a wide range of techniques, including ATR FT-IR, HRMAS NMR, XPS, and EDX spectroscopy. In particular, isotopic labeling experiments enabled us to probe the coordination mode adopted by the SPO ligand bound to the nanoparticle surface by ATR FT-IR spectroscopy. In combination with a series of control experiments we speculate that the SPO ligand demonstrates ligand-metal cooperative effects and plays a seminal role in the heterolytic hydrogenation mechanism.
Partial photocatalytic oxidations of 3-pyridinemethanol and 3-picoline by TiO2 prepared in HCl, HNO3 and H2SO4 at different temperatures
?etinkaya, S?d?ka,Yurdakal, Sedat
, p. 237 - 247 (2021)
Home prepared TiO2 photocatalysts were prepared from TiCl4 precursor in the absence and presence of HCl (1?6 M), HNO3 (1 M) or H2SO4 (1 M) at room temperature (RT), 60 or 100 °C. The TiO2 catalysts were characterised by XRD, BET, SEM and TGA techniques. TiO2 catalyst could not form at low temperature (up to 60 °C) in the presence of H2SO4. Just rutile phase was obtained for all TiO2 samples prepared at RT and 60 °C in HCl or HNO3. At 100 °C mainly both brookite and rutile phases were obtained in the presence of HCl or HNO3, whilst mainly anatase phase appeared in the presence of H2SO4. Nanorod structured TiO2 was formed in the presence of 1 M HCl or HNO3 at RT and 60 °C. The prepared TiO2 catalysts were used for partial oxidation of 3-pyridinemethanol to 3-pyridinemethanal and vitamin B3 in water under UVA irradiation. Moreover, photocatalytic oxidation of 3-picoline, precursor of 3-pyridinemethanol, was also performed, but much lower product selectivity values were obtained with respect to 3-pyridinemethanol oxidation. However, selective 3-picoline oxidation could be performed at pH 2 with low activity. Degussa P25 was used for comparison and almost all home prepared catalysts showed a higher selectivity, but they showed to be less active than Degussa P25. The high selectivity of the home prepared samples was not due to the type of TiO2 phase, but mainly to the hydrophilicity of the TiO2 surface which allowed desorption of valuable products instead of their over-oxidation.
Silver-catalyzed hydrogenation of aldehydes in water
Jia, Zhenhua,Zhou, Feng,Liu, Mingxin,Li, Xingshu,Chan, Albert S. C.,Li, Chao-Jun
, p. 11871 - 11874 (2013)
Silver bullet: The first silver-catalyzed hydrogenation in water was developed. A silver complex containing a bulky monodentate phosphine ligand was used to generate alcohols from a broad range of aldehydes, including aliphatic, aromatic, and heterocyclic aldehydes. This method provides a direct and efficient route to alcohols from aldehydes and opens a new avenue in silver catalysis. Copyright
Synthesis of 1,5-bis(triphenylphosphonium)pentan-3-ol dichloride and its application to the preparation of 1,7-di(pyridin-3-yl)heptan-4-ol
Stivanello, Mariano,Leoni, Lucia,Bortolaso, Roberto
, p. 807 - 810 (2002)
The preparation of 1,7-di(pyridin-3-yl)-heptan-4-ol (1), an important intermediate in the synthesis of a series of novel cancer multidrug resistance (CMR) chemosensitizers, has been accomplished in high overall yield via the new bis-Wittig reagent 1,5-bis(triphenylphosphonium)pentan-3-ol dichloride (6), that can also be used in the preparation of other members of the class of CMRs.
Highly dispersed ruthenium hydroxide supported on titanium oxide effective for liquid-phase hydrogen-transfer reactions
Yamaguchi, Kazuya,Koike, Takeshi,Kim, Jung Won,Ogasawara, Yoshiyuki,Mizuno, Noritaka
, p. 11480 - 11487 (2008)
Supported ruthenium hydroxide catalysts (Ru(OH)x/support) were prepared with three different TiO2 supports (anatase TiO2 (TiO2(A), BET surface area: 316 m2g-1), anatase TiO2 (TiO2(B), 73m2 g-1), and rutile TiO2 (TiO2(C), 3.2 m2 g-1)), as well as an Al2O3 support (160 m2g -1). Characterizations with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and X-ray absorption fine structure (XAFS) showed the presence of monomeric ruthenium(III) hydroxide and polymeric ruthenium(III) hydroxide species. Judging from the coordination numbers of the nearest-neighbor Ru atoms and the intensities of the ESR signals, the amount of monomeric hydroxide species increased in the order of Ru(OH)x x/ TiO2(C) x/Al2O3 x/ TiO 2(B) x/TiO2(A). These supported ruthenium hydroxide catalysts, especially Ru(OH)x/TiO2(A), showed high catalytic activities and selectivities for liquid-phase hydrogen-transfer reactions, such as racemization of chiral secondary alcohols and the reduction of carbonyl compounds and allylic alcohols. The catalytic activities of Ru(OH)x/TiO2(A) for these hydrogen-transfer reactions were at least one order of magnitude higher than those of previously reported heterogeneous catalysts, such as Ru(OHx/Al2O 3. These catalyses were truly heterogeneous, and the catalysts recovered after the reactions could be reused several times without loss of catalytic performance. The reaction rates monotonically increased with an increase in the amount of monomeric ruthenium hydroxide species, which suggests that the monomeric species are effective for these hydrogen-transfer reactions.
