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Chemistry Procedure (chemistry + procedure)

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Green chemistry procedure for the synthesis of cyclic ketals from 2-adamantanone as potential cosmetic odourants

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2002
M. T. Genta
Synopsis Some cyclic ketals derived from 2-adamantanone were obtained in excellent yields by microwave activation under solvent-free conditions, as a ,green chemistry' procedure. A number of experiments were performed to evaluate the most efficient catalytic conditions. The best results were obtained using a simple heterogeneous mixture of reagents and p -toluenesulphonic acid as the catalyst, without any solvent or support. The data are reported and compared with those obtained by other microwave-mediated syntheses or by classical method. In order to check the possible intervention of non-thermal microwave effects, the best experiment in ,dry media' was carried out with considerable lower yield by conventional heating, in a thermostated oil bath, under the same conditions as under microwaves (time, temperature and vessel). All the synthesized compounds were tested for their olfactive character and for a potential cosmetic use. The odour evaluation is reported. Résumé Des acétals cycliques dérivés de la 2-adamantanone ont été obtenus sous irradiation microonde sans solvant avec d'excellents rendements selon un procédé de ,chimie verte'. Un certain nombre d'experiences ont été réalisées pour optimiser les conditions de réaction. Les résultats obtenus par simple mélange hétérogène des réactifs et de l'acide p -toluènesulphonique 10% (p/p) comme catalyseur ont été décrits et comparés avec ceux obtenus avec les autres procédés, sous irradiation microonde ou par chauffage traditionnel. Dans le but de mettre en évidence l'éventuelle intervention d'effets spécifiques (non-purement thermiques) des microondes, la meilleure réaction obtenue en ,milieu sec' a été effectuée, avec des rendements nettement plus faibles, dans les mêmes conditions (temps et température), par chauffage classique. Les propriétés olfactives de tous les produits obtenus ont été déterminées pour évaluer une possible utilization cosmétique. [source]

Researches on a Novel Method for Fluorination of Halopyridazine Derivatives in Ionic Liquid

CHINESE JOURNAL OF CHEMISTRY, Issue 7 2007
Li Sun
Abstract A novel method for fluorination of halopyridazine derivatives with potassium fluoride was performed using a green chemistry procedure, including ionic liquid as an environmentally benign reaction medium and microwave irradiation with high yield. [source]

Diels-Alder Reactions of N -Functionalized Acryloyl , -Pyrrolidone Derivatives Using FeCl3·6H2O as an Efficient Catalyst under Solvent-free Conditions

CHINESE JOURNAL OF CHEMISTRY, Issue 6 2007
Wen Pei
Abstract Diels-Alder reactions of N -functionalized acryloyl , -pyrrolidone derivatives were investigated, which were catalyzed by FeCl3·6H2O as an efficient catalyst under solvent-free conditions at room temperature. The corresponding cycloadducts with functionalized-pyrrolidone were prepared in high yield with high stereoselectivity by a green chemistry procedure. N -Functionalized acryloyl pyrrolidone derivatives, a kind of pyrrolidone-functionalized chelating ,,, -unsaturated ketone usable as a dienophile in Diels-Alder reaction, were synthesized by N -acylation procedure in ionic liquid as a novel synthetic method. [source]

Backbone amide linker (BAL) strategy for N, -9-fluorenylmethoxycarbonyl (Fmoc) solid-phase synthesis of peptide aldehydes,

JOURNAL OF PEPTIDE SCIENCE, Issue 9 2005
Joseph C. Kappel
Abstract A rapid and efficient strategy has been developed for the general synthesis of complex peptide aldehydes. N, -Benzyloxycarbonylamino acids were converted to protected aldehyde building blocks for solid-phase synthesis in four steps and moderate overall yields. The aldehydes were protected as 1,3-dioxolanes except for one case where a dimethyl acetal was used. These protected amino aldehyde monomers were then incorporated onto 5-[(2 or 4)-formyl-3,5-dimethoxyphenoxy]butyryl-resin (BAL-PEG-PS) by reductive amination, following which the penultimate residue was introduced by HATU-mediated acylation. The resultant resin-bound dipeptide unit, anchored by a backbone amide linkage (BAL), was extended further by routine Fmoc chemistry procedures. Several model peptide aldehydes were prepared in good yields and purities. Some epimerization of the C -terminal residue occurred (10% to 25%), due to the intrinsic stereolability conferred by the aldehyde functional group, rather than any drawbacks to the synthesis procedure. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source]

Green chemistry procedure for the synthesis of cyclic ketals from 2-adamantanone as potential cosmetic odourants

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2002
M. T. Genta
Synopsis Some cyclic ketals derived from 2-adamantanone were obtained in excellent yields by microwave activation under solvent-free conditions, as a ,green chemistry' procedure. A number of experiments were performed to evaluate the most efficient catalytic conditions. The best results were obtained using a simple heterogeneous mixture of reagents and p -toluenesulphonic acid as the catalyst, without any solvent or support. The data are reported and compared with those obtained by other microwave-mediated syntheses or by classical method. In order to check the possible intervention of non-thermal microwave effects, the best experiment in ,dry media' was carried out with considerable lower yield by conventional heating, in a thermostated oil bath, under the same conditions as under microwaves (time, temperature and vessel). All the synthesized compounds were tested for their olfactive character and for a potential cosmetic use. The odour evaluation is reported. Résumé Des acétals cycliques dérivés de la 2-adamantanone ont été obtenus sous irradiation microonde sans solvant avec d'excellents rendements selon un procédé de ,chimie verte'. Un certain nombre d'experiences ont été réalisées pour optimiser les conditions de réaction. Les résultats obtenus par simple mélange hétérogène des réactifs et de l'acide p -toluènesulphonique 10% (p/p) comme catalyseur ont été décrits et comparés avec ceux obtenus avec les autres procédés, sous irradiation microonde ou par chauffage traditionnel. Dans le but de mettre en évidence l'éventuelle intervention d'effets spécifiques (non-purement thermiques) des microondes, la meilleure réaction obtenue en ,milieu sec' a été effectuée, avec des rendements nettement plus faibles, dans les mêmes conditions (temps et température), par chauffage classique. Les propriétés olfactives de tous les produits obtenus ont été déterminées pour évaluer une possible utilization cosmétique. [source]