Authors:Zine Eddine Hamami, Laurent Vanoye, Pascal Fongarland, Claude de Bellefon and Alain Favre-Reguillon
An efficient and metal-free method for the oxidation of aldehydes to the corresponding carboxylic acids has been developed. In a simple continuous-flow photochemical reactor, the use of camphorquinone (CQ) irradiated with a white light-emitting diode (LED) source enhanced the autoxidation of aldehydes. Under 5 bar of oxygen, visible light, and 0.3 mol% of CQ, the rate of oxidation was increased from 6 times with 2-ethylhexanal to 30 times for n-nonanal. The large interfacial area generated by a segmented flow apparatus associated with radicals formed by photooxidation of CQ ensures metal-free high throughput of carboxylic acids under safe conditions.
The present study reports a differential scanning calorimetry (DSC) study of the solid aldehydes: 4-hydroxybenzaldehyde [123-08-0]
1; 4-hydroxy-3-methoxybenzaldehyde (vanillin) [121-33-5] 2; 3-ethoxy-4-hydroxybenzaldehyde (ethyl vanillin) [121-32-4] 3; 3,4-dimethoxybenzaldehyde (veratraldehyde) [120-14-9] 4 and 4-methoxycinnamaldehyde [1963-36-6] 5, in the temperature interval from T=268 K to their respective melting temperatures. Temperatures, enthalpies and entropies of fusion and the heat capacities
of the compounds as a function of temperature are reported.
Authors:V. Belevskii, S. Belopushkin and V. Feldman
ESR spectra of -irradiated, at –196 °C, solutions of acetic and propionic aldehydes in freon-11 and freon-113 affected by aldehyde concentration, temperature, and the action of light have been studied. It has been shown that the radical cations CH3CHO+ are converted into neutral radicals CH3
O and CH3
HOH and the cations CH3CH2CHO+. are converted to RO and CH3
HCHO due to ion-molecular reactions of proton transfer /CH3
O and CH3
HCHO/ of hydrogen atom transfer /CH3
Authors:F. Langmaier, M. Mládek, K. Kolomaznik, J. Šívarová and S. Sukop
Hydrolysates from chromed leather waste obtained in powdered form on an industrial scale by using biotechnical methods were
analysed by TG an DSC techniques. Besides about 9% (mass/mass) of moisture, around 1% (mass/mass) of cyclohexylamine was found
in the pulverized hydrolysates. Calorimetric measurement of the reaction heats of the reactions of the hydrolysates with commercially
available aldehydes indicates that their reactivity decreases in the sequenceglutardialdehyde>>methylglyoxal≈acetaldehyde>>glyoxal>formaldehyde.
Authors:L. Fuks, E. Gniazdowska, P. Kozminski and J. Mieczkowski
Technetium(I) tricarbonyl complexes may form with the pyridine aldehyde thiosemicarbazones (TSCs), in which chelating ligand
is bound tri- or bidentately. Intend of the presented work was to check, if labeling the N-heterocyclic TSCs with tricarbonyl [99mTc]-technetium(I) may lead to formation of the complexes suitable for the radiopharmaceutical purposes. Syntheses of the complexes
were provided in the conditions analogous to those performed in the nuclear medicine laboratories. Main physicochemical properties
of the complexes important in the medicinal chemistry were studied. Relevant results of the numerical calculations remain
in fair agreement with these properties.
Authors:Jing-Hua Li, Ning Zhang, Xiao-Tao Li, Jin-Yun Wang and Sheng-Jun Tian
The stability of the inclusion complex of β-CD with cinnamic aldehyde was investigated by means of TG and DSC. The mass loss takes place in three stages: dehydration occurs at 50–120°C; dissociation of β-CD·C9H8O proceeds in the range 200–260°C; and decomposition of β-CD begins at 280°C. The kinetics of the dissociation of β-CD·C9H8O was studied by means of thermogravimetry both at constant temperature and with linearly increasing temperature. The results demonstrate that the dissociation of β-CD·C9H8O is dominated by a one-dimensional diffusion process. The activation energyE is 160 kJ mol−1, and the pre-exponential factorA is 5.8×1014 min−1. Scanning electron microscope observations and the results of crystal structure analysis are in good agreement with those of thermogravimetry.
Authors:A. Eréméev, V. Loukjanov and An. Nesmejanov
The following results of distribution of initial activity (μCi) in the synthesis products have been obtained: Initial14CO2−490.0±65.0, final gas−142.4±35.0, products−134.1±22.0 (C1−29.3; C2−5.7; C3−9.6; C4−9.8; C5−6.4; C6−6.9; C7−2.0; not identified products−54.4); carboxyl products −25.7±3.6 (C1+C2−2.2; C3−10.1; C4−0.4; C5−0.8; C6−2.5; C7−7.6; C8−1.4; C9−0.6); deposit of polymers on the surface of the ozonator −52.3±8.2. The mean values of specific activity of the carbonyl
and carboxyl fractions has nearly the same values of activity as the initial14CO2 (27.0±3.6 Ci/mM), the specific activities of carbonyl products increased from 15±4 (C1) to 60±15 (C6) μCi/mM. The IR and mas-spectra of the polymeric product are given.
Authors:Mouheddin Alhaffar, Rami Suleiman, S. M. Shakil Hussain and Bassam El Ali
The hydroformylation reaction is one of the largest industrial catalytic processes producing millions of tons of aldehydes annually [ 1 ]. The hydroformylation can be performed at lower temperature and pressure
Authors:Mohammad Abdollahi-Alibeik and Marjan Pouriayevali
aldehydes, anilines and dihydropyrane for the synthesis of pyranotetrahydroquinolines (Scheme 1 ). To the best of our knowledge, this is the first report of the use of MCM-41 supported TPA as solid acid catalyst in the imino Diels–Alder reaction