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78-93-3Relevant articles and documents
Fluorescence excitation spectrum of the 2-butoxyl radical and kinetics of its reactions with NO and NO2
Lotz,Zellner
, p. 2607 - 2613 (2001)
The (A ← X) fluorescence excitation spectrum of the 2-C4H9O(X) (2-butoxyl) radical in the wavelength range 345-390 nm was obtained using a combined laser photolysis/laser-induced fluorescence (LIF) technique following the generation of the radicals by excimer laser photolysis of 2-butylnitrite at λ = 351 nm. The fluorescence excitation spectrum shows 5 vibronic bands, where the dominant progression corresponds to the CO-stretching vibration in the first electronically excited state with v′CO = (560 ± 10) cm-1. The transition origin was assigned at v00 = (26768 ± 10) cm-1 (λ00 = (373.58 ± 0.15) nm). The kinetics of the reactions of the 2-butoxyl radical with NO and NO2 at temperatures between T = 223-305 K and pressures between p = 6.5-104 mbar have been determined. The rate coefficients for both reactions were found to be independent of total pressure with kNO = (3.9 ± 0.3) × 10-11 cm3 s-1 and kNO2 = (3.6 ± 0.3) times; 10-11 cm3 s-1 at T = 295 K. The Arrhenius expressions have been determined to be kNO = (9.1 ± 2.7) × 10-12 exp((3.4 ± 0.6) kJ mol-1/RT) cm3 s-1 and kNO2 = (8.6 ± 3.3) × 10-12 exp((3.3 ± 0.8) kJ mol-1/RT) cm3 s-1. In addition, the radiative lifetime of the 2-C4H9O(A) radical after excitation at λ = 365.938 nm in the (0,1) band has been determined to be τrad(2-C4H9O(A)) = (440 ± 80) ns. Quenching rate constants of the 2-C4H9O(A) radical were measured to be kq = (4.7 ± 0.3) × 10-10 cm3 s-1 and kq = (5.0 ± 0.4) × 10-12 cm3 s-1 for 2-butylnitrite and nitrogen, respectively.
Homogeneous Hydrogenation of α,β-Unsaturated Ketones and Aldehydes Catalyzed by Co2(CO)8-Di(tertiary phosphine) Complexes
Murata, Kazuhisa,Matsuda, Akio
, p. 1899 - 1900 (1981)
The cobalt complexes modified by some di(tertiary phosphine)s as ligands were found to be much more active catalysts than Co2(CO)8 for the hydrogenation of α,β-unsaturated ketones and aldehydes under hydroformylation conditions.
Mutation of serine-39 to threonine in thermostable secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus changes enantiospecificity
Tripp, Allie E.,Burdette, Douglas S.,Zeikus, J. Gregory,Phillips, Robert S.
, p. 5137 - 5141 (1998)
The substrate specificity of wild-type and Ser39 → Thr (S39T) secondary alcohol dehydrogenase (SADH) from Thermoanaerobacter ethanolicus was examined. The S39T mutation increases activity for 2-propanol without any significant effect on NADP+ binding. There is no significant effect of the mutation on the primary and secondary alcohol specificity of SADH. However, an effect on the enantiospecificity of SADH by the S39T mutation is demonstrated. Throughout the temperature range from 15 to 55 °C, wild-type SADH exhibits a preference for (S)-2-pentanol. In contrast, a temperature- dependent reversal of enantiospecificity is observed for 2-butanol, with a racemic temperature of 297 K. Throughout the same range of temperatures, S39T SADH exhibits higher enantiospecificity for the (R)-enantiomers of both 2- butanol and 2-pentanol. Examination of individual k(cat)/K(m) values for each enantiomer of the chiral alcohols reveals that the effect of the mutation is to decrease (S)-2-butanol specificity, and to preferentially enhance (R)-2- pentanol specificity relative to (S)-2-pentanol. These results are the first step toward expanding the synthetic utility of SADH to allow efficient preparation of a range of (R)-alcohols.
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Arzoumanian,Metzger
, p. C1,C2 (1973)
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Fischer,Lehnig
, p. 3410 (1971)
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Syntheses of ketonated disulfide-bridged diruthenium complexes via C-H bond activation and C-S bond formation
Sugiyama, Hiroyasu,Hossain, Md. Munkir,Lin, Yong-Shou,Matsumoto, Kazuko
, p. 3948 - 3956 (2000)
The α-C-H bonds of 3-methyl-2-butanone, 3-pentanone, and 2-methyl-3-pentanone were activated on the sulfur center of the disulfide-bridged ruthenium dinuclear complex [{RuCl(P(OCH3)3)2}2(μ-S2)(μ-Cl)2] (1) in the presence of AgX (X = PF6, SbF6) with concomitant formation of C-S bonds to give the corresponding ketonated complexes [{Ru(CH3CN)2(P(OCH3)3)2}(μ-SSCHR1COR2){Ru(CH3CN)3( P(OCH3)3)2}]X3 ([5](PF6)3, R1 = H, R2 = CH(CH3)2, X = PF6; [6](PF6)3, R1 = CH3, R2 = CH2CH3, X = PF6; [7](SbF6)3, R1 = CH3, R2 = CH(CH3)2, X = SbF6). For unsymmetric ketones, the primary or the secondary carbon of the α-C-H bond, rather than the tertiary carbon, is preferentially bound to one of the two bridging sulfur atoms. The α-C-H bond of the cyclic ketone cyclohexanone was cleaved to give the complex [{Ru(CH3CN)2(P(OCH3)3)2}(μ-SS-1-cyclohexanon-2-yl){Ru(CH3CN)3(P(OC H3)3)2}](SbF6)3 ([8](SBF6)3). And the reactions of acetophenone and p-methoxyacetophenone, respectively, with the chloride-free complex [{Ru(CH3CN)3(P(OCH3)3)2}2(μ-S2)]4+ (3) gave [{Ru(CH3CN)2(P(OCH3)3)2}(μ-SSCH2COAr){Ru(CH3CN)3(P(OCH3)3)2}] (CF3SO3)3 ([9](CF3SO3)3, Ar = Ph; [10](CF3SO3)3, Ar = p-CH3OC6H4). The relative reactivities of a primary and a secondary C-H bond were clearly observed in the reaction of butanone with complex 3, which gave a mixture of two complexes, i.e., [{Ru(CH3CN)2(P(OCH3)3)2}(μ-SSCH2COCH2-CH3){Ru(CH3CN)3 (P(OCH3)3)2}](CF3SO3)3 ([11](CF3SO3)3) and [{Ru(CH3CN)2(P(OCH3)3)2} (μ-SSCHCH3COCH3){Ru(CH3CN)3(P(OCH3)3)2}](CF3SO3)3 ([12](CF3SO3)3), in a molar ratio of 1:1.8. Complex 12 was converted to 11 at room temperature if the reaction time was prolonged. The relative reactivities of the α-C-H bonds of the ketones were deduced to be in the order 2°> 1°> 3°, on the basis of the consideration of contributions from both electronic and steric effects. Additionally, the C-S bonds in the ketonated complexes were found to be cleaved easily by protonation at room temperature. The mechanism for the formation of the ketonated disulfide-bridged ruthenium dinuclear complexes is as follows: Initial coordination of the oxygen atom of the carbonyl group to the ruthenium center, followed by addition of an α-C-H bond to the disulfide bridging ligand, having S=S double-bond character, to form a C-S-S-H moiety, and finally completion of the reaction by deprotonation of the S-H bond.
High-turnover supramolecular catalysis by a protected ruthenium(II) complex in aqueous solution
Brown, Casey J.,Miller, Gregory M.,Johnson, Miles W.,Bergman, Robert G.,Raymond, Kenneth N.
, p. 11964 - 11966 (2011)
The design of a supramolecular catalyst capable of high-turnover catalysis is reported. A ruthenium(II) catalyst is incorporated into a water-soluble supramolecular assembly, imparting the ability to catalyze allyl alcohol isomerization. The catalyst is protected from decomposition by sequestration inside the host but retains its catalytic activity with scope governed by confinement within the host. This host-guest complex is a uniquely active supramolecular catalyst, capable of >1000 turnovers.
Greatly improved activity in ruthenium catalysed butanone synthesis
Van der Drift,Mul,Bouwman,Drent
, p. 2746 - 2747 (2001)
In situ mixing of ruthenium trichloride with one equivalent of 1,10-phenanthroline yields a highly active catalyst for synthesis of butanone from buta-1,3-diene.
Homogeneous Redox Catalysts Based on Heteropoly Acid Solutions: IV. Tests of Methyl Ethyl Ketone Synthesis Catalysts in the Presence of Equipment Corrosion Products (Metal Cations)
Gogin, L. L.,Zhizhina, E. G.
, p. 580 - 591 (2021/09/28)
Abstract: The effect of equipment corrosion products (transition metal cations) on the physicochemical and catalytic properties of a homogeneous Pd(II)+HPA-x (Mo–V–P heteropoly acid containing x vanadium atoms) catalyst developed for the two-stage oxidation of n-butene to methyl ethyl ketone (MEK) with oxygen has been studied. The thermal stability of a solution of a catalyst based on HPA-x in the presence of transition metal cations has been determined. The composition of the two-component catalyst recommended for pilot testing of the MEK process has been optimized.
Green oxidation of amines by a novel cold-adapted monoamine oxidase mao p3 from psychrophilic fungi pseudogymnoascus sp. p3
Bia?kowska, Aneta M.,Jod?owska, Iga,Szymczak, Kamil,Twarda-Clapa, Aleksandra
supporting information, (2021/10/25)
The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30? C, retains 75% of activity at 20? C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.