BiMo基复合氧化物催化剂丙烷直接氧化至丙烯醛研究

The effects of the available zoon above the catalyst bed on the performance of the catalyst were investigated. It has been suggested that propylene is an intermediate species in the reaction of propane to acrolein， and a two-step reaction scheme is proposed， the first step is oxidative dehydrogenation of propane to propylene in the gas phase then followed by the second step， the selective oxidation of propylene to acrolein on the surface of the catalyst. The performance of the catalyst depends on both the oxidative dehydrogenation of propane to propylene in the gas phase and the selective oxidation of propylene to acrolein on the catalyst surface. The thermal cracking， homogeneous oxidative dehydrogenation and heterogeneous catalytic dehydrogenation of propane as well as the selective catalytic oxidation of propane to acrolein over BiMoO based mixed oxides catalysts were studied. Under the optimum reaction conditions of propane dehydrogenation and selective oxidation of propylene， the selectivity and the yield of acrolein approached to 45mol% and 14mol%， respectively under about 30mol% propane conversion.     

Determination of Acrylamide and Acrolein in Smoke from Tobacco and E-Cigarettes

Acrylamide and acrolein are two short-chained hazardous compounds with neurotoxic, carcinogenic, and mutagenic effects. The aim of this paper is to describe a fast and simple procedure for simultaneous determination of both acrylamide and acrolein under standard conditions, suggest a suitable calibration protocol for custom analysis, and demonstrate its applicability to the analysis of gaseous products from, e.g., cigarettes, cigars, or electronic cigarettes. A gas chromatography–mass spectrometry (GC–MS) method was developed to quantify acrylamide and acrolein in smoke vapor from electronic cigarettes, tobacco cigarettes, and cigars. Nonionic and highly polar molecules with a low boiling point and molecular mass need a suitable derivatization method to achieve appropriate retention and selectivity on commonly used relatively nonpolar stationary phases and to enhance the molecular mass for easy MS detection. The derivatization of acrylamide and acrolein was carried out by a bromination method with elemental bromine. The dibromo derivatives were extracted into an organic solvent and following a dehydrobromination procedure the samples were injected into the GC–MS system. Important experimental parameters were varied, after which the bromination time was defined as 30 min, and the injector temperature and the starting temperature of gradient were set at 280 and 50 °C respectively. Acrolein was found in all tested samples, while acrylamide was detected only in smoke from normal tobacco. Possible mechanisms for the formation of these unsaturated compounds in the samples are discussed. After its validation the newly developed method was successfully and reliably applied to the analysis of both compounds. This short method provides an easy way to determine acrylamide and acrolein in gaseous samples.

     

不同材料滤嘴对卷烟主流烟气中挥发性羰基化合物截滤性能的研究

吸烟是引起肺癌及相关疾病的主要原因[1]。挥发性羰基化合物(如甲醛、乙醛、丙醛、丙酮、丙烯醛、巴豆醛、丁酮和丁醛)是卷烟主流烟气中含量较高的一类有害成分,含量从几十到几百微克不等[2-3]。这些挥发性羰基化合物特别是甲醛、丙烯醛及巴豆醛具有纤毛毒性,与氰化氢和氨一起,     

Radiation-induced crosslinking of cellulose with acrolein

The process of radiation-induced crosslinking of cellulose is found to be highly influenced by radiation dosage and dose as well as by the solvents used and their concentration. The best crease resistance has been obtained in cases when cellulose is crosslinked with acrolein in the vapor phase. Moreover, the process is entirely radiation-induced and practically no homopolymer is formed. Chemical analysis and investigations of infrared spectra indicate that crosslinking proceeds on vinyl as well as on aldehyde groups of acrolein.     

The cycloaddition of the 1,3-butadiene radical cation with acrolein and methyl vinyl ketone

The 1,3-butadiene radical cation reacts with acrolein and methyl vinyl ketone to produce ‘stable’ adducts. The nature of the reaction and the structures of the adducts were investigated by collisional activation decomposition (CAD) combined with tandem mass spectrometry (MS/MS), and also by Fourier transform mass spectrometry. The CAD spectra of gas-phase adducts were compared with those of suitable model compounds. On that basis, it was determined that the 1,3-butadiene radical cation undergoes a cycloaddition with these α,β-unsaturated carbonyl compounds. The butadiene radical cation serves as the ‘ene’, and the acrolein and methyl vinyl ketone react as dienes, forming cycloadducts having 2-ethenyl-2,3-dihydropyran radical cation structures.     

On the performance of quantum chemical methods to predict solvatochromic effects: the case of acrolein in aqueous solution

The performance of the Hartree-Fock method and the three density functionals B3LYP, PBE0, and CAM-B3LYP is compared to results based on the coupled cluster singles and doubles model in predictions of the solvatochromic effects on the vertical n-->pi* and pi-->pi* electronic excitation energies of acrolein. All electronic structure methods employed the same solvent model, which is based on the combined quantum mechanics/molecular mechanics approach together with a dynamical averaging scheme. In addition to the predicted solvatochromic effects, we have also performed spectroscopic UV measurements of acrolein in vapor phase and aqueous solution. The gas-to-aqueous solution shift of the n-->pi* excitation energy is well reproduced by using all density functional methods considered. However, the B3LYP and PBE0 functionals completely fail to describe the pi-->pi* electronic transition in solution, whereas the recent CAM-B3LYP functional performs well also in this case. The pi-->pi* excitation energy of acrolein in water solution is found to be very dependent on intermolecular induction and nonelectrostatic interactions. The computed excitation energies of acrolein in vacuum and solution compare well to experimental data.     

Evaluation of silica gel cartridges coated in situ with acidified 2,4-dinitrophenylhydrazine for sampling aldehydes and ketones in air

A procedure for coating in situ silica gel in prepacked cartridges with 2,4-dinitrophenylhydrazine (DNPH) acidified with hydrochloric acid is described. The coated cartridge was compared with a validated DNPH impinger method for sampling organic carbonyl compounds (aldehydes and ketones) in diluted automotive exhaust emissions and in ambient air for subsequent analysis of the DNPH derivatives by high performance liquid chromatography. Qualitative and quantitative data are presented that show that the two sampling devices are equivalent. The coated cartridge is ideal for long-term sampling of carbonyls at sub to low parts-per-billion level in ambient air or for short-term sampling of carbonyls at low ppb to parts-per-million level in diluted automotive exhaust emissions. An unknown degradation product of acrolein has been tentatively identified as x-acrolein. The disappearance of acrolein in the analytical sample matrix correlates quantitatively almost on a mole for mole basis with the growth of x-acrolein. The sum of the concentration of acrolein and x-acrolein appears to be invariant with time.     

Fragmentation of protonated thioether conjugates of acrolein using low collision energies

The protonated mercapturic acid conjugate of acrolein, S-(3-oxopropyl)-N-acetyl-L-cysteine (I), undergoes facile retro-Michael loss of acrolein in the gas phase. To determine whether extensive loss of acrolein would impede structural characterization of acrolein-peptide adducts, fragmentation reactions of a series of conjugates, formed by 1,4-Michael addition of acrolein to peptides and cysteine derivatives, were investigated at collision cell potentials up to ?50 V using a triple quadrupole mass spectrometer. Differences in fragmentation dynamics suggest protonation at the sulfur of the N-acetylcysteine conjugate I facilitates retro-Michael elimination of acrolein with a low activation energy relative to other fragmentations. Analogous fragmentation was eliminated after borohydride reduction of the aldehyde to an alcohol. Retro-Michael fragmentation was not significant for acrolein conjugates of glutathione derivatives, suggesting that proton sequestration occurs in peptides with multiple amide linkages even when the peptide does not contain a basic amino group. An unexpected outcome of these experiments was the observation of a facile gas-phase cleavage of peptides on the N-terminal side of S-(3-oxopropyl)cysteine residues. Such fragmentation behavior may prove useful for locating cysteine residues in peptides.     

Determination of Acrylamide and Acrolein in Smoke from Tobacco and E-Cigarettes

Acrylamide and acrolein are two short-chained hazardous compounds with neurotoxic, carcinogenic, and mutagenic effects. The aim of this paper is to describe a fast and simple procedure for simultaneous determination of both acrylamide and acrolein under standard conditions, suggest a suitable calibration protocol for custom analysis, and demonstrate its applicability to the analysis of gaseous products from, e.g., cigarettes, cigars, or electronic cigarettes. A gas chromatography–mass spectrometry (GC–MS) method was developed to quantify acrylamide and acrolein in smoke vapor from electronic cigarettes, tobacco cigarettes, and cigars. Nonionic and highly polar molecules with a low boiling point and molecular mass need a suitable derivatization method to achieve appropriate retention and selectivity on commonly used relatively nonpolar stationary phases and to enhance the molecular mass for easy MS detection. The derivatization of acrylamide and acrolein was carried out by a bromination method with elemental bromine. The dibromo derivatives were extracted into an organic solvent and following a dehydrobromination procedure the samples were injected into the GC–MS system. Important experimental parameters were varied, after which the bromination time was defined as 30 min, and the injector temperature and the starting temperature of gradient were set at 280 and 50 °C respectively. Acrolein was found in all tested samples, while acrylamide was detected only in smoke from normal tobacco. Possible mechanisms for the formation of these unsaturated compounds in the samples are discussed. After its validation the newly developed method was successfully and reliably applied to the analysis of both compounds. This short method provides an easy way to determine acrylamide and acrolein in gaseous samples.     

Acrolein detection based on alcohol dehydrogenase inhibition

This paper presents the effect of acrolein on three dehydrogenases and proposes a fast spectrometric method for acrolein analysis. We have found that alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AlDH) are inhibited by low acrolein concentrations (0.2?mM) while inhibition of glutamate dehydrogenase (GDH) is not observed even at higher acrolein concentrations (1?mM). Acrolein is a suicide substrate for AlDH and ADH inhibition by acrolein is competitive. Cysteine (L-Cys) and glutathione (GSH) react with acrolein and thus reduce its expected inhibitory effect. ADH was chosen to develop a spectrophotometric method for acrolein analysis based on enzyme inhibition. The calibration curve is linear between 0.2 and 1.0?mM acrolein.     

Quantitatively resolving mixtures of isobaric compounds using chemical ionization mass spectrometry by modulating the reactant ion composition

Acrolein (C(3)H(4)O) and 1-butene (C(4)H(8)) can both be individually detected by proton transfer chemical ionization mass spectrometry (CI-MS). However, because these compounds are isobaric, mixtures of these two compounds cannot be resolved since both compounds react with H(3)O(+) via a proton-transfer reaction to form a protonated molecule that is detected at a nominal mass-to-charge ratio of 57 (m/z 57). While both compounds react with H(3)O(+) only acrolein reacts to any significant extent with H(3)O(+)(H(2)O). Recognizing that the electrical potential applied to a drift tube reaction mass spectrometer provides a simple and effective means for varying the relative intensity of the H(3)O(+) and H(3)O(+)(H(2)O) reactant ions we have developed a method whereby we make use of this reactivity difference to resolve mixtures of these two compounds. We demonstrate a technique where the individual contributions of acrolein and 1-butene within a mixture can be quantitatively resolved by systematically changing the reagent ion from H(3)O(+) to H(3)O(+)(H(2)O) through control of the electric potential applied to the drift tube reaction region of a proton transfer reaction mass spectrometer.     

Methods for Preparation of Stable Gas-Vapor Mixtures with Fixed Concentration of Volatile Components on the Basis of Buffer Effect of Heterogeneous Systems

Theoretical concepts of multiple gas extraction are checked experimentally. The possibility is studied of preparing stable gas-vapor mixtures with fixed concentrations of styrene, acrolein, and other volatile organic compounds.     

The structure of acrolein in a liquid crystal phase

The (1)H NMR spectrum of a sample of acrolein dissolved in the nematic liquid crystal phase I52 has been analysed to yield 18 dipolar couplings between all the magnetic nuclei in the molecule; moreover, the (13)C and (13)C{(1)H} NMR spectra of a sample of acrolein in CDCl(3) were recorded and analysed to determine the indirect J(ij) couplings. The data were used to obtain the relative positions of the carbon and hydrogen atoms, assuming that these are independent of the conformations generated by rotation around the C--C bond through an angle phi, and to obtain a probability distribution P(phi). It has been found that in the liquid phase, the distribution is a maximum at the trans form whereas the abundance of the cis form is significantly smaller compared with that found by microwave spectroscopy or high level quantum mechanical calculations. Such calculations produced also a suitable force field needed to develop suitable strategies for vibrational correction procedure in the case of flexible molecules.     

Determination of molecular line parameters for acrolein (C(3)H(4)O) using infrared tunable diode laser absorption spectroscopy

Acrolein (C(3)H(4)O) molecular line parameters, including infrared (IR) absorption positions, strengths, and nitrogen broadened half-widths, must be determined since they are not included in the high resolution transmission (HITRAN) molecular absorption database of spectral lines. These parameters are required for developing a quantitative analytical method for measuring acrolein in a single puff of cigarette smoke using tunable diode laser absorption spectroscopy (TDLAS). The task is complex since acrolein has many highly overlapping infrared absorption lines in the room temperature spectrum and the cigarette smoke matrix contains thousands of compounds. This work describes the procedure for estimating the molecular line parameters for these overlapping absorption lines in the wavenumber range (958.7-958.9 cm(-1)) using quantitative reference spectra taken with the infrared lead-salt TDLAS instrument at different pressures and concentrations. The nitrogen broadened half-width for acrolein is 0.0937 cm(-1)atm(-1) and to our knowledge, is the first time it has been reported in the literature.     

Determination of patterns of biologically relevant aldehydes in exhaled breath condensate of healthy subjects by liquid chromatography/atmospheric chemical ionization tandem mass spectrometry

A method for the simultaneous determination of several classes of aldehydes in exhaled breath condensate (EBC) was developed using liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI-MS/MS). EBC is a biological matrix obtained by a relatively new, simple and noninvasive technique and provides an indirect assessment of pulmonary status. The measurement of aldehydes in EBC represents a biomarker of the effect of oxidative stress caused by smoke, disease, or strong oxidants like ozone. Malondialdehyde (MDA), acrolein, alpha,beta-unsaturated hydroxylated aldehydes [namely 4-hydroxyhexenal (4-HHE) and 4-hydroxynonenal (4-HNE)], and saturated aldehydes (n-hexanal, n-heptanal and n-nonanal) were measured in EBC after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Atmospheric pressure chemical ionization of the analytes was obtained in positive-ion mode for MDA, and in negative-ion mode for acrolein, 4-HHE, 4-HNE, and saturated aldehydes. DNPH derivatives were separated on a C18 column using variable proportions of 20 mM aqueous acetic acid and methanol. Linearity was established over 4-5 orders of magnitude and limits of detection were in the 0.3-1.0 nM range. Intra-day and inter-day precision were in the 1.3-9.9% range for all the compounds. MDA, acrolein and n-alkanals were detectable in all EBC samples, whereas the highly reactive 4-HHE and 4-HNE were found in only a few samples. Statistically significant higher concentrations of MDA, acrolein and n-hexanal were found in EBC from smokers.     

丙烯醛及其衍生物基态脱羰反应机理的理论研究

用从头算自洽场分子轨道方法和能量梯度技术，研究丙烯醛及其衍生物基态脱羰反应的机理，用二级微扰方法考虑电子相关效应。结果表明基态丙烯醛脱羰为一简单反应，反应涉及三中心过渡态。取代基对丙烯醛脱羰反应仅有较小的影响。从计算的势垒可以推得基态丙烯醛及其衍生物热脱羰是很困难的，但是，光激发得到的丙烯醛很可能首先通过内转换成系间窜跃回到基态，然后发生脱羰反应，即基态脱羰很可能在其光解离反应机理中起着重要作用。     

N-heterocyclic carbene (NHC)-catalyzed direct amidation of aldehydes with nitroso compounds

NHC-catalyzed direct amidation of aldehydes with nitroso compounds is a powerful method for the synthesis of N-arylhydroxamic acids. A variety of aryl, alkyl, alkenyl, and heterocyclic aldehydes were found to give excellent yields of the corresponding N-arylhydroxamic acids. This chemistry was also extended to the synthesis of chiral N-arylhydroxamic acids by kinetic resolution of alpha-branched aldehydes, a domino amidation-redox amination reaction of acrolein, and a three-component reaction for the synthesis of N-arylaziridines.     

Tandem Michael addition and intramolecular aldol cyclization of 1,2-dideoxy-1-nitroheptitols derived from sugars

The base-catalyzed Michael addition of primary nitro compounds derived from sugars with 2 equiv of methyl vinyl ketone or acrolein was followed, in situ, by an asymmetric intramolecular aldol cyclization, thus yielding 2-acyl-4-glyco-4-nitrocyclohexanol derivatives with high diastereoselectivity.     

磷酸锆催化甘油气相脱水制备丙烯醛

以沉淀法、水热合成法和浸渍法制备了磷酸锆催化剂,通过X射线衍射、热重分析、氮气物理吸附、红外光谱和Hammett指示剂法对催化剂进行了表征,并将该催化剂用于甘油气相脱水反应.研究表明,由沉淀法得到的磷酸锆经过400℃焙烧后能达到最佳催化活性,在温和条件下,甘油可完全转化,丙烯醛选择性为81%,反应24h内催化剂失活不明显.不同方法制备的磷酸锆其结构和表面酸性显著不同,催化剂表面酸性对催化剂活性、丙烯醛选择性和催化剂的寿命均有较大影响.     

Atmospheric fate of methacrolein. 2. Formation of lactone and implications for organic aerosol production

We investigate the oxidation of methacryloylperoxy nitrate (MPAN) and methacrylicperoxy acid (MPAA) by the hydroxyl radical (OH) theoretically, using both density functional theory [B3LYP] and explicitly correlated coupled cluster theory [CCSD(T)-F12]. These two compounds are produced following the abstraction of a hydrogen atom from methacrolein (MACR) by the OH radical. We use a RRKM master equation analysis to estimate that the oxidation of MPAN leads to formation of hydroxymethyl-methyl-α-lactone (HMML) in high yield. HMML production follows a low potential energy path from both MPAN and MPAA following addition of OH (via elimination of the NO(3) and OH from MPAN and MPAA, respectively). We suggest that the subsequent heterogeneous phase chemistry of HMML may be the route to formation of 2-methylglyceric acid, a common component of organic aerosol produced in the oxidation of methacrolein. Oxidation of acrolein, a photo-oxidation product from 1,3-butadiene, is found to follow a similar route generating hydroxymethyl-α-lactone (HML).