Formation of acetaldehyde via photocarbonylation of methane with CO

Direct photocarbonylation of methane to give acetaldehyde occurred when a mixture of methane and CO dissolved in benzene was subjected to UV irradiation at λ < 290 nm. The reaction was accelerated by rhodium RhCl(CO)(PR₃)₂ complexes, where R = alkyl, Ph, or OPh.     

Modification of Surface Reactivity by CO: Effects on Decomposition and Polymerization of Acetaldehyde on Ru(0001)

The adsorption and reaction of acetaldehyde on the clean and CO pre-covered Ru(0001) surfaces have been investigated using temperature programmed desorption method. On the clean Ru(0001) surface, the decomposition of acetaldehyde is the main reaction channel, with little polymerization occurring. However, on the CO pre-covered Ru(0001) surface, the decomposition of acetaldehyde is inhibited considerably with increasing CO coverage. Whereas, the polymerization occurs efficiently, especially at high CO coverage (θ_CO>0.5 ML), which is strongly CO coverage dependent. Combined with previous studies, the well-ordered hexagonal structure of CO layer formed on the Ru(0001) surface at high CO coverage that matches the configuration of paraldehyde is likely to be the origin of this remarkable phenomenon.     

Highly enantioselective aldol reaction of acetaldehyde and isatins only with 4-hydroxydiarylprolinol as catalyst: concise stereoselective synthesis of (R)-convolutamydines B and E, (−)-donaxaridine and (R)-chimonamidine

A highly enantioselective aldol reaction of acetaldehyde and a wide scope of isatins has been presented only using readily available 4-hydroxydiarylprolinol as catalyst, affording various desired 3-substituted 3-hydroxyindolin-2-one adducts with moderate to high yield (up to 95%) and good enantioselectivities (up to 98% ee). This method not only represents an example of concise stereoselective synthesis of enantiopure (R)-convolutamydines B and E, but also firstly exhibits expedient asymmetric synthesis optically active (−)-donaxaridine and (R)-chimonamidine.     

A new insight into the Pfitzinger reaction. A facile synthesis of 6-sulfamoylquinoline-4-carboxylic acids

The unusual formation of 6-sulfamoylquinoline-4-carboxylic acids from 5-sulfamoylisatins under the conditions of Pfitzinger reaction is described. Key step in the suggested mechanism is the reaction of in situ generated acetaldehyde with the hydrolytically cleaved isatin ring. The suggested mechanism has been confirmed by dynamic LCMS measurements and by reactions with isotopically labeled reactants.     

Positive Photoreactive Polyimides. II. Preparation and Characterization of Polyimide Precursors Containing α-(2-Nitrophenyl)ethyl Ester Side Chains

The monomers were derived from pyromellitic dianhydride and α-(2-nitrophenyl)ethanol, which was prepared by selective reduction of 2-nitroacetophenone. Polyimide precursors were synthesized by an interfacial polycondensation technique. Their thermal properties in nitrogen were studied by dynamic thermogravimetry. The photore-arrangement of 2-nitrobenzyl ester having a methyl group at the α-position compared to that of the unsubstituted ester was investigated by infrared spectrophotometry. The polymers obtained in this study gave a high proportion of photorearrangement to show high sensitivity. The exposed areas dissolved in 2% aqueous KOH, forming high resolution patterns because they did not swell during the developing process.     

A synthesis and biological screening of newly substituted 9-methyl-6-aryl-[1,2,4]triazolo[4,3-a][1,8]naphthyridines using chloranil

An effective, mild, and convenient method for the synthesis of 10 new substituted 9-methyl-6-aryl-[1,2,4]triazolo[4,3-a][1,8]naphthyridines (5a–j) by the oxidation of the corresponding 2-(2-ethylidenehydrazinyl)-3-aryl-1,8-naphthyridines (4a–j) using chloranil under conventional method has been described. The structures of synthesized compounds (5a–j) were established on the basis of their elemental analysis and spectral (IR, Mass, ¹³C- and¹H-NMR) data. The new compounds were synthesized with the objective of studying their antibacterial activity. The reaction will be characterized by easy workup, good efficacy, simple purification of the products, and availability of catalyst.     

Selective electrocatalysis of acetaldehyde oxime reduction on (111) sites of platinum single crystal electrodes and nanoparticles surfaces

The reduction of acetaldehyde oxime (AO) in acid medium on platinum surfaces is a structure sensitive reaction that takes place almost exclusively on (111) sites of Pt electrodes, and it is strongly inhibited on Pt(100) and Pt(110) surfaces. A study using stepped electrodes with (111) terraces and monoatomic steps either with (100) and (110) orientation shows that the activity of the electrode is also dependent on the terrace width, i.e., the wider the terrace is, the higher current density is recorded and the more positive the peak potential for AO reduction appears. Moreover, in the electrodes with (100) step sites, the reduction process appears at more negative potential than the electrodes with (111) step sites. Nanoparticles with some preferential orientations were also tested for the AO reduction reaction to check the presence of (111) ordered domains on the nanoparticles surface. Dedicated to Teresa Iwasita on the occasion of her retirement and for her contributions to Electrochemistry.     

顶空进样气相色谱法检测啤酒中乙醛

建立了项空自动进样气相色谱法测定啤酒发酵液中乙醛含量的方法.检测条件优化为:顶空进样器平衡温度70℃,平衡时间30 min;色谱柱初始温度40℃,经程序升温10℃/min到180℃;柱流量1.2 mL/min,加盐量1.8g.对不同浓度的乙醛标准溶液进样测定,标准曲线证明线性良好,R2为0.999,线性范围2～64 m...     

Electrocatalytic reduction of NAD+ at glassy carbon electrode modified with single-walled carbon nanotubes and Ru(III) complexes

A simple procedure was developed to prepare a glassy carbon electrode modified with carbon nanotubes and Ruthenium (III) complexes. First, 25 μl of dimethyl sulfoxide–carbon nanotubes solutions (0.4 mg/ml) was cast on the surface of the glassy carbon electrode and dried in air to form a carbon nanotube film at the electrode surface. Then, the glassy carbon/carbon nanotube-modified electrode was immersed into a Ruthenium (III) complex solution (direct deposition) for a short period of time (10–20 s for multiwalled carbon nanotubes and 20–40 s for single-walled carbon nanotubes). The cyclic voltammograms of the modified electrode in aqueous solution shows a pair of well-defined, stable, and nearly reversible redox couple, Ru(III)/Ru(II), with surface-confined characteristics. The attractive mechanical and electrical characteristics of carbon nanostructures and unique properties and reactivity of Ru complexes are combined. The transfer coefficient (α), heterogeneous electron transfer rate constants (k _s), and surface concentrations (Γ) for the glassy carbon/single-walled carbon nanotubes/Ru(III) complex-, glassy carbon/multiwalled carbon nanotubes/Ru(III) complex-, and glassy carbon/Ru(III) complex-modified electrodes were calculated using the cyclic voltammetry technique. The modified electrodes showed excellent catalytic activity, fast response time, and high sensitivity toward the reduction of nicotinamide adenine dinucleotide in phosphate buffer solutions at a pH range of 4–8. The catalytic cathodic current depends on the nicotinamide adenine dinucleotide concentration. In the presence of alcohol dehydrogenase, the modified electrode exhibited a response to addition of acetaldehyde. Therefore, the main product of nicotinamide adenine dinucleotide electroreduction at the Ru(III) complex/carbon nanotube-modified electrode was the enzymatically active NADH. The purposed sensor can be used for acetaldehyde determination.     

Determination of formaldehyde and acetaldehyde in air by HPLC with fluorescence detection

Summary Sensitive detection of atmospheric formaldehyde and acetaldehyde can be achieved by use of silica-gel cartridges impregnated with 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) to form fluorescent DAI hydrazones. The hydrazones are extracted with acetonitrile and separated by reversed-phase HPLC with fluorimetric detection. The low detection limits achieved (0.25 ppb CH₂O or CH₃CHO for sampling periods of 1 h) means that the sensitivity of the method is better than that of the classical dinitrophenylhydrazine (DNPH) method. Several experimental conditions, such as collection and reaction efficiency, interference by ozone and storage stability of blank and sampled cartridges have been investigated. There were no significant differences between ambient concentrations of CH₂O and CH₃CHO measured concurrently with the DAIH and DNPH techniques (10–20% in the 0–5 ppb range).