Comments concerning the HPLC separation of acrolein from other C3 carbonyl compounds as 2,4-dinitrophenylhydrazones: A proposal for improvement

The separation of the toxicologically important aldehyde acrolein from other carbonyl compounds by high performance liquid chromatography after derivatization to 2,4-dinitrophenylhydrazones is critically discussed on the basis of a selection of published methods. A method is proposed whereby the compounds acrolein, acetone, and propanal may be reproducibly separated to baseline by a reversed phase HPLC procedure employing a ternary mixture of methanol, water, and acetonitrile as mobile phase.     

Lewis酸催化高区域选择合成对位柑菁醛的研究

Ｌｅｗｉｓ酸催化高区域选择合成对位柑菁醛的研究尹笃林，银董红，李谦和（湖南师范大学精细催化合成研究所，长沙４１００８１）关键词月桂烯，丙烯醛，对位柑菁醛，Ｄｉｅｌｓ－Ａｌｄｅｒ反应，Ｌｅｗｉｓ酸，络合催化。１．前言可从松节油资源中制取的月桂烯（ｍｙｒ...     

Spectroscopic Investigation on the Acrolein Hydration

The progress with time of the UV and ¹H NMR spectra of an aqueous solution of acrolein shows that, contrary to assumptions of previous authors, hydracrylaldehyde is not the only reaction product: in addition to it and its hydrated form, spontaneous oxidation products are present.     

Kinetic wavelength-pair method as an alternative approach to simultaneous multi-component analysis

The kinetic wavelength-pair method involves adapting a well established principle to the simultaneous kinetic-based determination of two or more compounds with diode-array detection. It relies on measuring the difference in the rate of change of the absorbance with time at two preset wavelength pairs such that the values of these measuring parameters are the result of the contribution of one or two components. The theoretical basis adapted to first-order kinetic-based determinations was established and checked on four systems. The method thus developed was compared with other differential kinetic methods and applied to the resolution of formaldehyde-acrolein mixtures.     

Regio- and stereoselectivity in the Diels–Alder reaction of vinylallenes with acrolein: an ab initio study

To explore the regio- and stereoselectivity in Diels–Alder reactions of vinylallenes with acrolein, a parent vinylallene/acrolein system and a methyl-substituted vinylallene/acrolein system were studied. Ab initio calculations were used to identify eight transition state structures for each of the two Diels–Alder reactions at various computational levels (RHF/6-31G(d), RHF/6-311G(2d), B3LYP/6-311G(2d), and MP2/6-311G(2d)). The relative energies of the endo and exo transition states along with the regioselectivity have been determined from these calculations. In the parent vinylallene/acrolein system, the endo s-cis transition structure is the preferred stereoselectivity at all levels of theory, however, there is no regioselectivity. In the methyl substituted vinylallene/acrolein system, the endo s-trans transition state tends to compete with the endo s-cis transition state at the RHF levels of theory and is 1 kcal/mol more stable at the B3LYP/6-311G(2d) level of theory. Also, in the methyl-substituted system, there is now a definite preference for one regioisomer over the other. Both Diels–Alder reaction systems are asynchronous with the methyl-substituted system being more pronounced.     

Hydrogenation of conjugated CC and CO bonds: Quantum chemical preview before metal catalysis

Hydrogenation of acrolein, ethylene and formaldehyde by molecular hydrogen in gas phases, as a preview before metal catalysis, is investigated using density functional theory (PW91 and B3LYP), ab initio (MP2), and composite theoretical methods (G2, CBS-QB3, and CBS-APNO). Compared to the most accurate CBS-APNO method used in this paper, PW91 functional underestimates the barrier while B3LYP reproduces close results. All the reaction barriers are predicted to be no less than 70 kcal/mol and the CC hydrogenation is thermodynamically favored. Kinetically, however, the hydrogenation of CO bond is more favorable than that of the CC bond, especially for the isolated CO. The conjugation effect in acrolein greatly reduces the kinetic preference for the isolated CO hydrogenation. It is revealed that there is a good relationship between the energy barrier and the increase of the molecular H₂ bond length from the reactant to transition state.     

丙烷选择氧化催化剂Mo-V-Zr-O的研究

研究了Zr添加量对Mo-V-O基催化剂丙烷选择氧化制丙烯醛催化性能的影响.对催化剂的BET、X射线衍射、H2-程序升温还原、NH3-程序升温脱附和异丙醇分解表征结果表明,Zr的添加改变了催化剂的物相结构、氧化还原性和酸碱性质,从而影响催化剂的催化性能,其中Mo2VZr0.5Ox催化剂表现出较好的催化活性和丙烯醛选择性.     

Adsorption and thermal chemistry of acrolein and crotonaldehyde on Pt(111) surfaces

The surface chemistry of acrolein and of crotonaldehyde on Pt(111) single-crystal surfaces was investigated under vacuum by temperature-programmed desorption (TPD) and reflection-absorption infrared (RAIRS) spectroscopies. The main thermal decomposition path seen for both compounds was the expected decarbonylation of the unsaturated aldehyde to carbon monoxide and the corresponding olefin (ethene and propene, respectively), but small amounts of propene and ketene were detected in the case of acrolein as well. The RAIRS data indicate that while acrolein initially adsorbs with its plane parallel to the surface and interacts mainly via the carbonyl group, crotonaldehyde adopts a more complex geometry where the main interaction to the metal is via a rehybridization of the C=C double bond. It is suggested here that the changes in adsorption geometry induced by substitutions in the C=C double bond may be responsible for the observed changes in the subsequent reactivity of the adsorbed unsaturated aldehydes.     

Facile Synthesis of 9-Acetyl/Formyl/Cyano-Substituted Pyrano[2,3-f]flavones and Chromones Using the Baylis–Hillman Reaction

Condensation of 8-formyl-7-hydroxyflavones (2a–f) and 8-formyl-7-hydroxy-2-(2′-furyl)-3-methylchromone (2g) with methyl vinyl ketone (3), acrolein (4), and acrylonitrile (5) in the presence of diazabicyclo[2.2.2]octane (DABCO) under an N₂ atmosphere at room temperature using Baylis–Hillman reaction conditions afforded 9-acetyl/formyl/cyano-substituted pyrano2,3-f]flavones (6a–f, 7a–f, 8a–f) and chromones (6g, 7g, 8g).     

Carbohydrate pyrolysis mechanisms from isotopic labeling: Part 3. The Pyrolysis of d-glucose: Formation of C3 and C4 carbonyl compounds and a cyclopentenedione isomer by electrocyclic fragmentation mechanisms

The flash pyrolysis of d-glucose was investigated by the use of ¹³C labeling, in conjunction with GC/MS. Co-pyrolysis of uniformly labeled and unlabeled d-glucose established the extent of unimolecular formation of each of the pyrolysis products. A complete set of singly labeled d-glucose isotopologs was used to determine the origin of specific carbons within each of the pyrolysis products. The results were compared with the expected labeling patterns that arise when the cyclic Grob 1,3-diol fragmentation and the tandem alkaline pinacol rearrangement/retro-aldol fragmentation (TAPRRAF) discovered from the pyrolysis of glycerin are used to initiate breakage of the six-carbon chain of d-glucose. The most promising rationalizations provided by this exercise are presented herein, for the formation of six C₃ and eight C₄ acyclic carbonyl-containing pyrolysis products, and for 3-cyclopentene-1,2-dione.