107-89-1Relevant academic research and scientific papers
Online ATR-IR investigations and mechanistic understanding of the carbonylation of epoxides - The selective synthesis of lactones or polyesters from epoxides and CO
Allmendinger, Markus,Zintl, Manuela,Eberhardt, Robert,Luinstra, Gerrit A.,Molnar, Ferenc,Rieger, Bernhard
, p. 971 - 979 (2004)
In situ ATR-IR spectroscopy is applied as a powerful tool to study the factors that control the reaction of epoxides with carbon monoxide in the presence of [Lewis acid]+ [Co(CO)4]- salts. Based on these investigations, a consistent mechanistic scheme is presented, comprising the main lactone and polyester products and minor components, e.g., acetone and crotonic acid derivatives. β-Alkoxy-acyl-cobalttetracarbonyl species are shown to be key intermediates from which two reaction routes start in dependence of the applied Lewis acid (LA). Labile LA-alkoxy combinations favor a backbiting process of the oxygen function on the Co-acyl bond, primarily producing lactone products. More stable LA-alkoxy entities are unreactive toward PO conversion and afford a polymerization reaction after the addition of a nucleophile. In that case, the Lewis acid remains bonded to the chain end.
Selective catalytic oxidation of glycerol to dihydroxyacetone
Painter, Ron M.,Pearson, David M.,Waymouth, Robert M.
, p. 9456 - 9459 (2010)
High selectivity and high yield characterize the oxidation of glycerol into dihydroxyacetone using catalyst 1, with benzoquinone or air as the oxidant. The mechanism proposed involves reversible palladium-alkoxide formation with the turnover-limiting reoxidation of the palladium complex. Copyright
Acid-Catalyzed Enolization and Aldol Condensation of Acetaldehyde
Baigrie, Lynn M.,Cox, Robin A.,Slebocka-Tilk, Henryka,Tencer, Michal,Tidwell, Thomas T.
, p. 3640 - 3645 (1985)
The condensation of acetaldehyde (1) to an equilibrium mixture of aldol (2) and crotonaldehyde (3) is second order in 1.An excess acidity analysis reveals that a water molecule is also involved in the rate-limiting step; the reaction is actually the base-assisted addition of vinyl alcohol to protonated 1, even in concentrated H2SO4.A previous report of a kinetically first-order conversion of 1 to 3 is shown to be due to the presence of a fast-reacting oligomer of 1.The reaction of 1 in D2SO4 leads to partially deuterated 3, a result ascribed to partial conversion of vinyl alcohol to deuterated 1.Hydrogen isotop exchange of 3 was also observed, but at a slower rate.The rates of enolization of 1 were studied by iodination and are consistent with previous results and the proposed mechanism.The interconversion of 2 and 3 is shown to proceed via the enol of 2; in this case the rate-limiting step is water attack on/water loss from protonated 3/2, not proton transfer at carbon.
Conversion of diols by dehydrogenation and dehydration reactions on silica-supported copper catalysts
Torresi,Díez,Luggren,Di Cosimo
, p. 119 - 129 (2013)
The gas-phase conversion of a 1,3-polyol (1,3-butanediol) containing primary and secondary OH functions was studied on a series of copper-silica catalysts, ZCuSiO2 (Z = 1-25 wt.% Cu), and thoroughly characterized by several techniques such as BET surface area, TPR, XRD, N2O chemisorption, and UV-vis-DRS. The physicochemical properties of the ZCuSiO 2 catalysts depended on whether the metal loading was above or below the copper monolayer surface coverage (Z = 13.5 wt.% Cu). Copper species presenting different degrees of interaction with the silica support were detected. At low Z values Cu0 dispersion was high (D ≈ 40%) due to a predominant contribution of nano-sized Cu species (3 nm) which are difficult to reduce, but for Z > 13.5 wt.%, D abruptly dropped to 3-8% because of formation of larger tridimensional Cu clustered species (30 nm) that reduced at lower temperatures because of a decreased copper-silica interaction. On ZCuSiO2 catalysts, dehydrogenation of the 1,3-butanediol secondary OH function prevailed over that of the primary one and therefore valuable ketones were the main reaction products. Consecutively to dehydrogenation, dehydration and hydrogenation reactions also took place. Products of the tandem reaction were the β-hydroxy ketone (4-hydroxy-2-butanone), the α,β- unsaturated ketone (methyl vinyl ketone) and the saturated ketone (methyl ethyl ketone). A direct 1,3-butanediol dehydration pathway toward methyl ethyl ketone was also found. Reaction pathways were strongly dependent on the Cu loading and therefore on the kind of Cu species (isolated or clustered). When compared at similar conversion levels, selectivity to the dehydrogenation product 4-hydroxy-2-butanone increased with Z suggesting that on large Cu0 particles 4-hydroxy-2-butanone was released to the gas phase before being converted in consecutive steps. On the contrary, on highly dispersed Cu 0 crystals of low Cu loading catalysts, 1,3-butanediol was readily dehydrated giving the saturated ketone. Kinetically relevant reaction steps of 1,3-butanediol conversion by dehydrogenation and dehydration were promoted on Cu0 sites. Dehydration of the intermediate 4-hydroxy-2-butanone also occurred on Cu0 sites. Turnover rates were constant on Cu0 nano particles and slightly higher on clustered species.
Chemoselective Oxidation of the Primary Alcohol Function of Diols Catalyzed by Zirconocene Complexes
Nakano, Tatsuya,Terada, Takanobu,Ishii, Yasutaka,Ogawa, Masaya
, p. 774 - 776 (1986)
Zirconocene complexes, Cp2ZrH2 and Cp2Zr2, catalyze the Oppenauer-type oxidation of alcohol functions to the corresponding carbonyl compounds in the presence of an appropriate hydrogen acceptor such as benzophenone.In the oxidation of primary α,ω-diols and of diols containing two secondary alcohol functions, one of the alcohol functions is selectively oxidized to form hydroxy aldehydes and hydroxy ketones, respectively, in substantial yields.The chemoselective oxidation of the primary alcohol function can be achieved in the oxidation of diols containing both the primary and secondary alcohol functions.
Kinetics and Mechanism of the Oxidation of Diols by Pyridinium Bromochromate
Rao, P. Surya Chandra,Suri, Deepa,Kothari, Seema,Banerji, Kalyan K.
, p. 285 - 290 (1998)
The kinetics of oxidation of four vicinal diols, four nonvicinal diols, and one of their monoethers by pyridinium bromochromate (PBC) have been studied in dimethyl sulfoxide.The main product of oxidation is the corresponding hydroxyaldehyde.The reaction is first-order with respect to each the diol and PBC.The reaction is acid-catalyzed and the acid dependence has the form: kobs = a + b+>.The oxidation of ethanediol exhibited a primary kinetic isotope effect (kH/kD = 6.70 at 298 K).The reaction has been studied in 19 organic solvents including dimethyl sulfoxide and the solvent effect has been analyzed using multiparametric equations.The temperature dependence of the kinetic isotope effect indicates the presence of a symmetrical transition state in the rate-determining step.A suitable mechanism has been proposed.
Oxidation of Olefins by Palladium(II). 12. Product Distributions and Kinetics of the Oxidation of 3-Buten-2-ol and 2-Buten-1-ol by PdCl42- in Aqueous Solution
Zaw, Kyaw,Henry, Patrick M.
, p. 1842 - 1847 (1990)
The rate expression for oxidation of both allyl alcohols was determined to be rate = k2->/+>->2, an expression identical in form with that found previously for the oxidation of ethene, allyl alcohol, and other acyclic olefins, indicating similar mechanisms.Contrary to previous reports, the product distribution from 3-buten-2-ol (6) was completely different from that for 2-buten-1-ol (7), indicating that fast isomerization into an equilibrium mixture before oxidation was not occuring.A short study of the rate of isomerization using deuteriated 6 and 7 confirmed that isomerization was slow under the oxidation conditions.The distributions gave considerable information on the effects of steric and electronic factors on the modes of hydroxypalladation.While allyl alcohol gave a 3/1 preference for addition of the Pd(II) to the center carbon due to the directing influence of the hydroxyl group, 6 gave 4/1 preference for addition of Pd(II) to the end carbon.The steric effect of the methyl is thus appreciable.With 7 the double bond is internal so steric factors are not important and the directing influence of the hydroxyl will be the important effect.The ratio of Pd(II) addition next to the carbon containing the hydroxyl group to addition to the other side of the double bond is 34/1, indicating considerable directing influence of the hydroxyl.The preference for secondary over primary hydride shift is 1.25, a value which indicates almost no carbonium ion character and considerable Pd(II)-H character.Using a specifically deuterated 7, the value of the deuterium isotope effect, kH/kD, can be determined by internal competitive hydride transfer by taking into account the positional preferance for secondary hydride shift.This value of 2.2 is close to values previously determined for ethene and allyl alcohol.
Rate constants for the gas-phase reactions of OH radicals with a series of hydroxyaldehydes at 296 ± 2 K
Baker, Jillian,Arey, Janet,Atkinson, Roger
, p. 7032 - 7037 (2004)
Using a relative rate method with in situ generation of the hydroxyaldehydes, rate constants for the reactions of the OH radical with 2-hydroxybutanal [CH3CH2CH(OH)CHO], 3-hydroxybutanal [CH3CH(OH)CH2CHO], 2-hydroxypropanal [CH 3CH(OH)CHO], 2-hydroxy-2-methylpropanal [(CH3) 2C(OH)CHO], and 3-hydroxy-propanal [HOCH2CH 2CHO] have been measured at atmospheric pressure and 296 ± 2 K. The hydroxy-aldehydes were generated in situ from the OH radical-initiated reactions of precursor compounds (1,2- and 1,3-butanediol, 2-methyl-2,4-pentanediol, 2-methyl-3-buten-2-ol, and cis-3-hexen-1-ol) and the rate constants for the reaction of OH radicals with the hydroxyaldehydes were determined relative to those for reaction of OH radicals with the precursor compound. The rate constants obtained (in units of 10-11 cm 3 molecule-1 s-1) were CH3CH 2CH(OH)CHO, 2.37 ± 0.23; CH3CH(OH)CH 2CHO, 2.95 ± 0.24; CH3CH(OH)CHO, 1.70 ± 0.20; (CH3)2C(OH)CHO, 1.40 ± 0.25; and HOCH 2CH2CHO, 1.99 ± 0.29.
Exploring the biocatalytic scope of alditol oxidase from Streptomyces coelicolor
Van Hellemond, Erik W.,Vermote, Linda,Koolen, Wilma,Sonke, Theo,Zandvoort, Ellen,Heuts, Dominic P. H. M.,Janssen, Dick B.,Fraaije, Marco W.
, p. 1523 - 1530 (2009)
The substrate scope of the flavoprotein alditol oxidase (AldO) from Streptomyces coelicolor A3(2), recombinantly produced in Escherichia coli, was explored. While it has been established that AldO efficiently oxidizes alditols to D-aldoses, this study revealed that the enzyme is also active with a broad range of aliphatic and aromatic alcohols. Alcohols containing hydroxy groups at the C-1 and C-2 positions like 1,2,4-butanetriol (Km=170 mM, k cat -4.4s-1), 1,2-pentanediol (Km=52 mM, k cat=0.85 s-1) and 1,2-hexanediol (Km=97 mM, kcat=2.0s-1) were readily accepted by AldO. Furthermore, the enzyme was highly enantioselective for the oxidation of 1,2-diols [e.g., for l-phenyl-1,2-ethanediol the (R)-enantiomer was preferred with an Is-value of 74]. For several diols the oxidation products were determined by GC-MS and NMR. Interestingly, for all tested 1,2-diols the products were found to be the a-hydroxy acids instead of the expected α-hydroxy aldehydes. Incubation of (R)-1-phenyl-1,2-ethanediol with 18O-labelled water (H 218O) revealed that a second enzymatic oxidation step occurs via the hydrate product intermediate. The relaxed substrate specificity, excellent enantioselectivity, and independence of coenzymes make AldO an attractive enzyme for the preparation of optically pure 1,2-diols and α-hydroxy acids.
Fructose 1,6-Diphosphate Aldolase Catalyzed Stereoselective Synthesis of C-Alkyl and N-Containing Sugars: Thermodynamically Controlled C-C Bond Formations.
Durrwachter, John R.,Wong, Chi-Huey
, p. 4175 - 4181 (1988)
Fructose 1,6-diphosphate aldolase catalyzed aldol condensations have been used in syntheses of several new N-containing and C-alkyl sugars on 4-20 mmol scales.The enzyme is highly specific for dihydroxyacetone phosphate as donor but accepts a number of achiral and chiral aldehydes (both D and L isomers) as acceptors.Due to the reversible nature of the aldol reaction, a thermodynamically controlled approach was employed for the syntheses in which racemic aldehydes were used as substrates and thermodynamically more stable products were preferentially produced.
