1225-01-0Relevant academic research and scientific papers
Self-aldol condensation of unmodified aldehydes catalysed by secondary-amine immobilised in FSM-16 silica
Shimizu, Ken-Ichi,Hayashi, Eidai,Inokuchi, Takuro,Kodama, Tatsuya,Hagiwara, Hisahiro,Kitayama, Yoshie
, p. 9073 - 9075 (2002)
Self-aldol condensation of unmodified aldehydes was catalysed effectively by N-metlyl-3-aminopropylated FSM-16 mesoporous silica, whose activity was higher than that of homogeneous amine catalyst.
Condensation reactions of propanal over CexZr 1-xO2 mixed oxide catalysts
Gangadharan, Anirudhan,Shen, Min,Sooknoi, Tawan,Resasco, Daniel E.,Mallinson, Richard G.
, p. 80 - 91 (2010)
Vapor phase condensation reactions of propanal were investigated over CexZr1-xO2 mixed oxides as a model reaction to produce gasoline range molecules from short aldehydes found in bio-oil mixtures. Several operating parameters were investigated. These included the type of carrier gas used (H2 or He) and the incorporation of acids and water in the feed. Propanal is converted to higher carbon chain oxygenates on Ce xZr1-xO2 by two pathways, aldol condensation and ketonization. The major products of these condensation reactions include 3-pentanone, 2-methyl-2-pentenal, 2-methylpentanal, 3-heptanone and 4-methyl-3-heptanone. It is proposed that the primary intermediate for the ketonization path is a surface carboxylate. The presence of acids in the feed inhibits the aldol condensation pathway by competitive adsorption that reduces the aldehyde conversion. Water also promotes ketonization and inhibits aldol condensation by increasing the concentration of surface hydroxyl groups that enhance the formation of surface carboxylates with the aldehyde. Hydrogen enhances cracking and production of light oxygenates and hydrocarbons. The light oxygenates may in turn be reincorporated into the reaction path, giving secondary products. However, the hydrocarbons do not react further. Analysis of the fresh and spent catalysts by XPS showed varying degrees of reduction of the oxide under different operating conditions that were consistent with the reaction results. Changing the proportion of the parent oxides showed that increased Zr favored formation of aldol products while increased Ce favored ketonization. This occurs by shifting the balance of the acid-base properties of the active sites.
Self-aldol condensation of aldehydes over Lewis acidic rare-earth cations stabilized by zeolites
Yan, Tingting,Yao, Sikai,Dai, Weili,Wu, Guangjun,Guan, Naijia,Li, Landong
, p. 595 - 605 (2021)
The self-aldol condensation of aldehydes was investigated with rare-earth cations stabilized by [Si]Beta zeolites in parallel with bulk rare-earth metal oxides. Good catalytic performance was achieved with all Lewis acidic rare-earth cations stabilized by
Development and evaluation of a candidate reference measurement procedure for the determination of 19-norandrosterone in human urine using isotope-dilution liquid chromatography/tandem mass spectrometry
Tai, Susan S.-C.,Xu, Bei,Sniegoski, Lorna T.,Welch, Michael J.
, p. 3393 - 3398 (2006)
19-Norandrosterone (19-NA) is the major metabolite of the steroid nandrolone, one of the most commonly abused anabolic androgenic agents. 19-NA exists mainly as the glucuronide form in human urine. A candidate reference measurement procedure for 19-NA in urine involving isotope dilution coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been developed and critically evaluated. The 19-NA glucuronide was enzymatically hydrolyzed, and the 19-NA along with its internal standard (deuterated 19-NA) was extracted from urine using liquid-liquid extraction prior to reversed-phase LC/MS/MS. The accuracy of the measurement of 19-NA was evaluated by a recovery study of added 19-NA. The recovery of the added 19-NA ranged from 99.1 to 101.4%. This method was applied to the determination of 19-NA in urine samples fortified with 19-NA glucuronide at three different concentrations (equivalent to 1, 2, and 10 ng/mL 19-NA). Excellent reproducibility was obtained with within-set coefficients of variation (CVs) ranging from 0.2 to 1.2%, and between-set CVs ranging from 0.1 to 0.5%. Excellent linearity was also obtained with correlation coefficients of all linear regression lines (measured intensity ratios vs mass ratios) ranging from 0.9997 to 0.9999. The detection limit for 19-NA at a signal-to-noise ratio of ～3 was 16 pg. The mean results of 19-NA yielded from hydrolysis of 19-NA glucuronide compared well with the theoretical values (calculated from the conversion of 19-NA glucuronide to 19-NA) with absolute relative differences ranging from 0.2 to 1.4%. This candidate reference measurement procedure for 19-NA in urine, which demonstrates good accuracy and precision and low susceptibility to interferences, can be used to provide an accuracy base to which routine methods for 19-NA can be compared and that will serve as a standard of higher order for measurement traceability.
Accelerating Amine-Catalyzed Asymmetric Reactions by Intermolecular Cooperative Thiourea/Oxime Hydrogen-Bond Catalysis
Afewerki, Samson,Córdova, Armando,Ibrahem, Ismail,Ma, Guangning,Zhang, Kaiheng
supporting information, p. 3043 - 3049 (2021/07/22)
The ability of intermolecular cooperative thiourea/oxime hydrogen-bond catalysis for improving and accelerating asymmetric aminocatalysis is presented. The two readily available hydrogen-bond-donating catalysts operates in synergy with a chiral amine catalyst to accomplish highly stereoselective transformations. The synergistic catalyst systems simultaneously activate both electrophiles and nucleophiles, and make the transformations more chemo- and stereoselective. This was exemplified by performing co-catalytic enantioselective direct intermolecular α-alkylation reactions of aldehydes, direct aldol reactions, and asymmetric conjugate reactions, which gave the corresponding products in high yields and enantiomeric ratios.
Kinetic Treatments for Catalyst Activation and Deactivation Processes based on Variable Time Normalization Analysis
Martínez-Carrión, Alicia,Howlett, Michael G.,Alamillo-Ferrer, Carla,Clayton, Adam D.,Bourne, Richard A.,Codina, Anna,Vidal-Ferran, Anton,Adams, Ralph W.,Burés, Jordi
supporting information, p. 10189 - 10193 (2019/06/25)
Progress reaction profiles are affected by both catalyst activation and deactivation processes occurring alongside the main reaction. These processes complicate the kinetic analysis of reactions, often directing researchers toward incorrect conclusions. We report the application of two kinetic treatments, based on variable time normalization analysis, to reactions involving catalyst activation and deactivation processes. The first kinetic treatment allows the removal of induction periods or the effect of rate perturbations associated with catalyst deactivation from kinetic profiles when the quantity of active catalyst can be measured. The second treatment allows the estimation of the activation or deactivation profile of the catalyst when the order of the reactants for the main reaction is known. Both treatments facilitate kinetic analysis of reactions suffering catalyst activation or deactivation processes.
Organic compound as well as preparation method and application thereof
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Paragraph 0039; 0041; 0058; 0060, (2019/10/04)
The invention relates to an organic compound as well as a preparation method and application thereof. The organic compound has a structural formula I shown in the specification, in the formula, R4 is H; R1, R2 and R3 are alkyl or H of which the carbon number is an integer; the total carbon number of R1, R2, R3 and R4 is 0-3; R5 and R6 are of an identical structure and are both saturated alkyl with 1-3 carbon atoms; A is a polyoxy alkenyl ether group, a sulfation polyoxy alkenyl ether group, an aliphatic, alicyclic or aromatic group which forms an ester group with adjacent oxygen atoms, or an aliphatic, alicyclic or aromatic group which comprises other ester groups. Due to a carbon chain structure similar to Guerbet alcohol and an alcoholic hydroxyl derivative structure at a para-site in the organic compound, the organic compound has excellent low-temperature properties and good degradability in a surfactant, ester type lubricating oil or a plasticizer.
Method for preparing high-carbon branched-chain secondary alcohol
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Paragraph 0037; 0038, (2019/10/01)
The invention relates to a method for preparing high-carbon branched-chain secondary alcohol. The method comprises the steps: preparing branched-chain olefin aldehyde through self-condensation of linear aliphatic aldehyde or branched-chain aliphatic aldehyde without tertiary carbon, performing a gas-liquid heterogeneous condensation reaction on the branched-chain olefin aldehyde and aliphatic ketone without tertiary carbon under the catalysis action of organic base so as to prepare branched-chain dienone, and performing hydrogenation on the branched-chain dienone so as to prepare unsaturated or saturated branched-chain secondary alcohol. The method has wide sources of raw materials and low cost, and the product has a certain structure, and is particularly suitable for preparation of secondary alcohol polyoxyethylene ether and secondary alcohol polyoxyethylene ether derivatives which have narrow molecular weight distribution; and the alcoholic hydroxyl group of the product is secondary alcohol which has a branched-chain structure but no tertiary carbon, the low temperature performance is excellent, and the biodegradability is good.
Catalytic Reactions of Homo- and Cross-Condensation of Ethanal and Propanal
Martsinkevich,Bruk,Dashko,Afaunov,Flid,Sedov
, p. 1032 - 1035 (2019/01/03)
Abstract: Processes of catalytic homocondensation of propanal and its cross-condensation with ethanal and methanal in the presence of aniline and amino acids have been studied. The dependence of the conversion of the reactants and selectivity of the homo/heterocondensation process on the catalyst nature and temperature has been revealed. It has been shown that the maximum acrolein selectivity is reached in the case of using benzoyl-substituted derivatives in water, with the proportion of the products of further condensation decreasing. The selectivity for the ethanal homocondensation product 2-butenal decreases simultaneously as a result of the formation of linear and branched oligomers of successive condensation.
Inter- and intramolecular aldol reactions promiscuously catalyzed by a proline-based tautomerase
Rahimi, Mehran,Geertsema, Edzard M.,Miao, Yufeng,Van Der Meer, Jan-Ytzen,Van Den Bosch, Thea,De Haan, Pim,Zandvoort, Ellen,Poelarends, Gerrit J.
supporting information, p. 2809 - 2816 (2017/04/03)
The enzyme 4-oxalocrotonate tautomerase (4-OT), which in nature catalyzes a tautomerization step as part of a catabolic pathway for aromatic hydrocarbons, was found to promiscuously catalyze different types of aldol reactions. These include the self-condensation of propanal, the cross-coupling of propanal and benzaldehyde, the cross-coupling of propanal and pyruvate, and the intramolecular cyclizations of hexanedial and heptanedial. Mutation of the catalytic amino-terminal proline (P1A) greatly reduces 4-OT's aldolase activities, whereas mutation of another active site residue (F50A) strongly enhances 4-OT's aldolase activities, indicating that aldolization is an active site process. This catalytic promiscuity of 4-OT could be exploited as starting point to create tailor-made, artificial aldolases for challenging self- and cross-aldolizations.
