Condensation Of Acetaldehyde Research Articles

Template synthesis and characterization of 16-membered octaazamacrocyclic complexes: a photoelectron spectroscopic study

A novel series of complexes of the type [MLX_2] where M= Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); X= C^- or NO_3^- were synthesized by template condensation of hydrazine hydrate, acetaldehyde, 2,4-pentanedione, and thiocarbohydrazide in the presence of divalent metal salt in methanolic solution. The complexes were characterized with the help of elemental analysis, conductance measurements, magnetic measurements, electronic, NMR, XPS, and infrared and far infrared spectral studies. Electronic spectra along with magnetic moments suggest 6-coordinated octahedral geometry for these complexes. The low value of molar conductance indicates them to be non-electrolytes.

Inorganic ammonium salts and carbonate salts are efficient catalysts for aldol condensation in atmospheric aerosols

In natural environments such as atmospheric aerosols, organic compounds coexist with inorganic salts but, until recently, were not thought to interact chemically. We have recently shown that inorganic ammonium ions, NH(4)(+), act as catalysts for acetal formation from glyoxal, a common atmospheric gas. In this work, we report that inorganic ammonium ions, NH(4)(+), and carbonate ions, CO(3)(2-), are also efficient catalysts for the aldol condensation of carbonyl compounds. In the case of NH(4)(+) this was not previously known, and was patented prior to this article. The kinetic results presented in this work show that, for the concentrations of ammonium and carbonate ions present in tropospheric aerosols, the aldol condensation of acetaldehyde and acetone could be as fast as in concentrated sulfuric acid and might compete with their reactions with OH radicals. These catalytic processes could produce significant amounts of polyconjugated, light-absorbing compounds in aerosols, and thus affect their direct forcing on climate. For organic gases with large Henry's law coefficients, these reactions could also result in a significant uptake and in the formation of secondary organic aerosols (SOA). This work reinforces the recent findings that inorganic salts are not inert towards organic compounds in aerosols and shows, in particular, that common ones, such as ammonium and carbonate salts, might even play important roles in their chemical transformations.

Alkaline hydrolysis of cinnamaldehyde to benzaldehyde in the presence of β‐cyclodextrin

AbstractA facile, novel, and cost‐effective alkaline hydrolysis process of cinnamaldehyde to benzaldehyde under rather mild conditions has been investigated systematically in the presence of β‐cyclodextrin (β‐CD), with water as the only solvent. β‐CD could form inclusion complex with cinnamaldehyde in water, with molar ratio of 1:1, so as to promote the reaction selectivity. The complex has been investigated experimentally and with computational methods. 1H‐NMR, ROESY, UV–Vis, and FTIR have been utilized to analyze the inclusion complex. It shows that the equilibrium constant for inclusion (Ka) is 363 M−1, and the standard Gibbs function for the reaction, ΔγG (298 K), is −14.6 kJ mol−1. In addition, the structures of the proposed inclusion compounds were optimized with hybrid ONIOM theory. Benzaldehyde could be obtained at an yield of 42% under optimum conditions [50°C, 18 h, 2% NaOH (w/v), cinnamaldehyde:β‐CD (molar ratio) = 1:1]. To explain the experimental data, NMR, FTIR, and elemental analysis results were used to determine the main reaction by‐product 1‐naphthalenemethanol. A feasible reaction mechanism including the retro‐Aldol condensation of cinnamaldehyde and the Aldol condensation of acetaldehyde and cinnamaldehyde in basic aqueous β‐CD solution has been proposed. The calculated activation energy for the reaction was 45.27 kJ mol−1 by initial concentrations method. © 2009 American Institute of Chemical Engineers AIChE J, 2010

3-Penten-2-one, a novel aldehyde adduct, is a biomarker for increased acetaldehyde in urine

Diagnostic profiling of urine for volatile compounds of around 400 patients using headspace solid-phase microextraction (HS-SPME) in alkaline conditions identified 3-penten-2-one (approximately 1 to >6.3 μmol/L) in 26 patients. Five were in barbiturate coma. 3-Penten-2-one, previously of unknown origin, was shown to be formed by aldol condensation of acetaldehyde with acetone or acetoacetate during analysis. Semi-quantification of acetaldehyde using in-fibre derivatisation HS-SPME, showed high concentrations in five urine (33–348 μmol/L) and two plasma (17 and 43 μmol/L) samples. Hence, urinary 3-penten-2-one is a useful biomarker for increased accumulation of acetaldehyde during abnormal metabolic stress.

Synthesis of chiral benzacridone derivatives by three-component condensation

A three-component condensation of (2-bornylidene)acetaldehyde and 2-naphthylamine with various, in particular, dissymmetrical, cyclic β-diketones afforded derivatives of 12-(2-bornylidene)methyl-8,9,10,12-tetrahydro-7H-benzo[a]acridin-11-one containing in the structure three and more asymmetrical carbon atoms. Steric factors govern the prevailing formation of (12R)-isomers of benzacridones (R/SH ≈ 7: 5) and the orientation of the substituents of the cyclohexenone fragment. These factors ensure also the regiospecificity of the reaction leading exclusively to the formation of 8,9-disubstituted benzacridones at the use of 4,5-disubstituted cyclohexane-1,3-diones.

Amine functional chloroaniline acetaldehyde condensate‐modified epoxy networks

AbstractAn investigation was carried out to modify the fracture toughness of cured diglycidyl ether of bisphenol‐A (DGEBA) resin networks with amine functional chloroaniline acetaldehyde condensate (AFCAC) as toughening agent. The resulting networks displayed significantly improved fracture toughness. The AFCAC was synthesized by the condensation reaction of chloroaniline and acetaldehyde in the acid medium (pH‐4) and characterized by FTIR and NMR spectroscopy, elemental analysis, viscosity measurements, and mole of primary and secondary amine analysis. The DGEBA and AFCAC were molecularly miscible but developed a two‐phase microstructure upon network formation. Epoxy/AFCAC compositions were systematically varied to study the effect of concentration on the impact, adhesive, tensile, and flexural properties of modified networks. The dynamic mechanical analysis and scanning electron microscopy studies showed two‐phase morphology in the cured networks where AFCAC particles were dispersed. The AFCAC‐modified epoxy network was thermally stable up to around 338°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A Kinetic and Mechanistic Study of the Amino Acid Catalyzed Aldol Condensation of Acetaldehyde in Aqueous and Salt Solutions

The amino acid catalyzed aldol condensation is of great interest in organic synthesis and natural environments such as atmospheric particles. However, kinetic and mechanistic information on these reactions is limited. In this work the kinetics of the aldol condensation of acetaldehyde in water and aqueous salt solutions (NaCl, CaCl2, Na2SO4, MgSO4) catalyzed by five amino acids (glycine, alanine, serine, arginine, and proline) at room temperature (295 +/- 2 K) has been studied. Monitoring the formation of three products, crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal, by UV-vis absorption over 200-1100 nm revealed two distinct kinetic regimes: at low amino acid concentrations (in all cases, below 0.1 M), the overall reaction was first-order with respect to acetaldehyde and kinetically limited by the formation of the enamine intermediate. At larger amino acid concentrations (at least 0.3 M), the kinetics was second order and controlled by the C-C bond-forming step. The first-order rate constants increased linearly with amino acid concentration consistent with the enamine formation. Inorganic salts further accelerated the enamine formation according to their pKb plausibly by facilitating the iminium or enamine formation. The rate constant of the C-C bond-forming step varied with the square of amino acid concentration suggesting the involvement of two amino acid molecules. Thus, the reaction proceeded via a Mannich pathway. However, the contribution of an aldol pathway, first-order in amino acid, could not be excluded. Our results show that the rate constant for the self-condensation of acetaldehyde in aqueous atmospheric aerosols (up to 10 mM of amino acids) is identical to that in sulfuric acid 10-15 M (kI approximately 10-7-10-6 s-1) clearly illustrating the potential importance of amino acid catalysis in natural environments. This work also demonstrates that under usual laboratory conditions and in natural environments aldol condensation is likely to be kinetically controlled by the enamine formation. Notably, kinetic investigations of the C-C bond-forming addition step would only be possible with high concentrations of amino acids.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Toughening of epoxy resin with amine functional aniline acetaldehyde condensate

AbstractThe diglycidyl ether of bisphenol‐A (DGEBA) resin was modified with amine functional aniline acetaldehyde condensate (AFAAC) and cured with an ambient temperature curing agent triethylene tetramine. The resulting networks displayed significantly improved fracture toughness. The AFAAC was synthesized by the condensation reaction of aniline and acetaldehyde in the acid medium (pH 4) and characterized by FTIR and NMR spectroscopy, elemental analysis, viscosity measurements, and mole of primary and secondary amine analysis. The DGEBA and AFAAC were molecularly miscible but developed a two‐phase microstructure upon network formation. Epoxy/AFAAC compositions were systematically varied to study the effect of AFAAC concentration on the impact, adhesive, tensile, and flexural properties of modified networks. The dynamic mechanical analysis and scanning electron microscopy studies showed two phase morphology in the cured networks, where AFAAC particles were dispersed. The AFAAC modified epoxy network was thermally stable up to around 280°C. POLYM. ENG. SCI., 47:1695–1702, 2007. © 2007 Society of Plastics Engineers

Synthesis of 4-Hydroxyisoleucine by the Aldolase–Transaminase Coupling Reaction and Basic Characterization of the Aldolase fromArthrobacter simplexAKU 626

Arthrobacter simplex AKU 626 was found to synthesize 4-hydroxyisoleucine from acetaldehyde, alpha-ketobutyrate, and L-glutamate in the presence of Escherichia coli harboring the branched chain amino acid transaminase gene (ilvE) from E. coli K12 substrain MG1655. By using resting cells of A. simplex AKU 626 and E. coli BL21(DE3)/pET-15b-ilvE, 3.2 mM 4-hydroxyisoleucine was produced from 250 mM acetaldehyde, 75 mM alpha-ketobutyrate, and 100 mM L-glutamate with a molar yield to alpha-ketobutyrate of 4.3% in 50 mM Tris-HCl buffer (pH 7.5) containing 2 mM MnCl(2) x 4H(2)O at 28 degrees C for 2 h. An aldolase that catalyzes the aldol condensation of acetaldehyde and alpha-ketobutyrate was purified from A. simplex AKU 626. Mn(2+) and pyridoxal 5'-monophosphate were effective in stabilizing the enzyme. The native and subunit molecular masses of the purified aldolase were about 180 and 32 kDa respectively. The N-terminal amino acid sequence of the purified enzyme showed no significant homology to known aldolases.

A novel strategy for enzymatic synthesis of 4-hydroxyisoleucine: identification of an enzyme possessing HMKP (4-hydroxy-3-methyl-2-keto-pentanoate) aldolase activity

A two-step enzymatic synthesis process of 4-hydroxyisoleucine is suggested. In the first step, the aldol condensation of acetaldehyde and alpha-ketobutyrate catalyzed by specific aldolase results in the formation of 4-hydroxy-3-methyl-2-keto-pentanoate (HMKP). In the second step, amination of HMKP by the branched-chain amino acid aminotransferase leads to synthesis of 4-hydroxyisoleucine. An enzyme possessing HMKP aldolase activity (asHPAL) was purified 2500-fold from a crude extract of Arthrobacter simplex strain AKU 626. Sequencing of the asHPAL structural gene showed that the purified enzyme belongs to the HpcH/HpaI aldolase family. The 4-hydroxyisoleucine was synthesized in vitro from acetaldehyde, alpha-ketobutyrate and l-glutamate using a coupled aldolase/branched-chain amino acid aminotransferase bienzymatic reaction.

Method for Mineralization Control of Acetaldehyde Condensation Urea by Additives

Method for Mineralization Control of Acetaldehyde Condensation Urea by Additives

Solvent and temperature effects on the electronic transitions of 3- H-indolo-2-dimethinehemicyanine dyes

Solvent effects on the UV/vis absorption spectra of five hemicyanine dyes 1, obtained by the condensation of (1,3,3-trimethylindolin-2-ylidene)acetaldehyde 2 with different substituted anilines 3, have been investigated. Analysis of the observed hypsochromic shifts using Reichardt's single parameter solvent polarity scale ( E T N) revealed that the dye obtained with 4-aminophenol is the most sensitive to solvent effects. Multiple regression analysis based on the Kamlet–Taft equation indicated that (i) the hydrogen bond donor properties and the dipolarity/polarizability of the solvent have an equal contribution to the solvatochromic behavior of the dye obtained with aniline, and (ii) the hydrogen bond accepting properties of the solvent have a significant contribution to the solvatochromic behavior of the 3-hydroxy-substituted dye. UV/vis absorption spectra were also recorded in mixtures of water and 2-propanol. A preferential solvation in 2-propanol was observed and quantified for all dyes. Finally, the effects of the temperature on the solvatochromism in binary mixtures were also investigated in order to reveal the susceptibilities of dye–water–propanol interactions. Increasing temperatures produced a depletion of the 2-propanol in the solvation shell of the hemicyanines.

Synthesis, characterization, and curing of {2,6–bis‐[2‐(bis‐oxiranylmethyl‐amino)‐methylbenzyl]‐phenyl}‐bis‐oxiranylmethylamine (BPBOMA)

AbstractThe curing behavior of epoxy resin prepared by reacting epichlorohydrin with amine functional aniline acetaldehyde condensate (AFAAC) was investigated using AFAAC as a curing agent. The epoxy resin, {2,6‐bis‐[2‐(bis‐oxiranylmethyl‐amino)‐methylbenzyl]‐phenyl}‐bis‐oxiranylmethylamine (BPBOMA), was characterized by FTIR and 1H‐NMR spectroscopy, viscosity measurement, and determination of epoxy content. Analysis of the curing reaction was followed by differential scanning calorimetry (DSC) analysis. To investigate the curing kinetic with AFAAC, dynamic DSC scans were made at heating rates of 5, 10, 15, and 20°C/min. The activation energy and frequency factor of the AFAAC formulation were evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3168–3174, 2006

Synthesis and characterisation of 3-H-indolo-2-dimethinehemicyanine dyes obtained by the condensation of (1,3,3-trimethylindolin-2-ylidene)acetaldehyde with anilines in acetic acid

Twenty, 1,3,3- trimethyl-2-[2-(2-Y-, 3- or 4-X-phenylamino)ethenyl]-3-H-indolium salts 1c– 1z were synthesised and characterised by their spectroscopic properties (UV–VIS, IR and NMR), ionisation constants (p K a), and solvatochromic behaviour. The assigned 3-H-indolo-2-dimethinehemicyanine structure was proven on the basis of NMR data; the strong deshielding of the NH proton from the phenylamino moiety and of the N(1)CH 3 protons from the 3-H-indole moiety (11.5–13.43 and 3.59–3.74 ppm, respectively) indicates partial positive charge at the nitrogen atoms of these groups. Such partial positive charge at both nitrogen atoms from the end of the trimethine chain is compatible with an electron delocalization through the cationic polymethine chain, which is characteristic of hemicyanine dyes. The positive charge at the mentioned NH group is also sustained by the obtained p K a values (8.05–9.37). The study concerning the solvatochromic behaviour revealed a small hypsochromic shift for all investigated dyes.

Aldol condensation of aldehydes over semicrystalline zeolitic-mesoporous UL-ZSM-5

The acid properties of UL-ZSM-5 materials were studied and found to be improved by a treatment in aqueous ammonia solutions. The catalytic properties in the aldol condensation of acetaldehyde with formaldehyde were examined after this treatment. The UL-ZSM-5 were found to be less sensitive to coke deactivation than ZSM-5 of comparable Si/Al ratio and more active than the mesostructured precursor.

Concurrent Phenomena Contributing to the Formation of the Aroma of Wine during Aging in Oak Wood: An Analytical Study

Red wine was stored in different oak barrels or in stainless steel, and samples were taken for two years to determine 79 aroma compounds. Aging in oak affects 41 compounds. The type of wood affects 11 compounds. At least seven different processes seem to take place concurrently in aroma evolution, and five such processes, affecting 37 compounds, are linked to the oak cask. These are extraction from the wood, oxidation of wine alcohols and amino acids, microbiological formation of ethyl phenols, sorption processes, and condensation of acetaldehyde with polyphenols. The wood can release linear gamma- and delta-lactones, beta-damascenone, and ionones. Some compounds are released very fast from wood, which suggests they lie in the external part of the wood. Some extraction profiles are too complex to be explained by physical processes. Finally, the levels of 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2-ethyl-5-methyl-4-hydroxy-3(2H)-furanone increase even in the reference wine, which suggests the presence of a precursor.

Standardization of catalyst preparation using reference catalyst: ion exchange of mordenite type zeolite: 1. Remarkable dealumination accompanying ion exchange

A joint study was organized to establish a standard set of conditions for the ion exchange of zeolite from sodium into proton-form. The sodium-form mordenite with Si/Al 2 = ca. 15 was ion exchanged into an NH 4-form, followed by calcination according to various recipes. Then various advanced techniques for characterization (ICP, TG, XPS, SEM, XRD, N 2 adsorption, 29Si and 27Al NMR, benzene diffusion, IR of OH and adsorbed pyridine and CO, ammonia TPD) were applied, and some test reactions (cracking of cumene, isopropylation of biphenyl, oligomerization of propene and chichibabin condensation of acetaldehyde and ammonia into picoline) were conducted. The ion exchange (removal of sodium) proceeded as expected, but remarkable differences were observed in physicochemical and catalytic properties of the thus-prepared proton-form samples. Exceptionally high temperature (383 K) for the ion exchange resulted in the structural degradation, while most samples exchanged at 333–353 K maintained the crystallinity and pore volume. The use of NH 4Cl slightly changed the crystal morphology. Extra-framework aluminum species was formed on most samples after calcination above 773 K. In contrast, calcination at 673 K maintained the framework aluminum. Therefore, the dealumination is considered to proceed after complete removal of ammonia from the ammonium-form zeolite. However, the proton-form zeolite was stable under dry conditions, so it is speculated that the dealumination was induced by the contact of the proton-form zeolite to atmosphere with humidity. The total and Brønsted acidity decreased with the dealumination, while Lewis acidity increased. On the other hand, rapid heating of the ammonium type zeolite caused narrowing of the micropores. These structural changes seriously affected the catalytic activities for various reactions.

Aldol condensation of the inferior aldehydes over dealuminated clinoptilolite

The catalytic performances of dealuminated clinoptilolite in the vapour-phase condensation of acetaldehyde and formaldehyde were investigated. The activity of dealuminated clinoptilolite in terms of the overall conversion of the acetaldehyde is comparable with that of the cation-exchanged forms (Na+, Ni2+, Fe3+). The dealumination process of clinoptilolite exhibits a favourable effect on the catalytic selectivity toward crotonaldehyde formation.

NOx reduction from diesel emissions over a non-transition metal zeolite catalyst: Effect of water in the feed

NO reduction activity with acetaldehyde over BaY is low in a dry feed, but significantly higher in the presence of water vapor. Aldol condensation of acetaldehyde takes place, polymerization of the resulting crotonaldehyde deactivates the catalyst. Water vapor prevents the formation of large amounts of carbonaceous deposits, either by suppressing the dehydration of aldol to crotonadehyde or by interacting with carbonaceous deposits or their precursors, transforming them to CO, CO2 and H2. Temperature-programmed oxidation (TPO) shows much lower coke formation after tests in the presence of water vapor. TPD–MS data show that nitromethane, a possible intermediate in the NOx reduction process, reacts with water on BaY forming NH3, COx and isocyanic acid HNCO. NOx conversion over BaY reaches values near 90% at 200°C and a GHSV of 30,000h−1 if the NOx initially contains both NO and NO2. No transition metal is involved in the reduction of NOx to NH3 and N2 over BaY.