Comportement des allylbenzenes chrometricarbonyle en milieu basique

Allylbenzene, estragole and safrole complexed by a Cr(CO)₃ unit react in THF and in the presence of tBuOK, with carbonyl compounds to produce exclusively the γ adducts. The para methoxy allylbenzene complexe opposed with ØCHO and furfural in excess affords ketones via in situ OPPENAUER-WOODWARD oxydation.     

Etude du pouvoir oxydant de quelques periodates de tetraalkylammonium en milieu non aqueux

The reactivity of some tetraalkylammonium periodates in periodate oxidation has been studied by electrochemistry in non-aqueous media. Conductimetric and spectrometric investigations suggest the existence of different forms of periodate, depending on the concentration and on the properties of the solvents. A study of the relation between structure and reactivity is introduced.     

Epoxyesters p‐menthaniques et pinaniques en milieu basique – Parfum de noix de coco

Base‐Induced Reactions of p ‐ Menthane‐ and Pinane‐Derived Epoxyesters – Coconut Fragrance The base‐induced isomerization of p‐menthane‐ and pinane‐derived epoxy esters was studied. The reaction is dependent on the structure of the terpene compound, the nature of the base, and experimental conditions. Among all the new synthesized compounds, one, 6a , emits a very strong fragrance of coconut. In the structure of this tricyclic lactone, the presence of a methyl substituent is essential.     

Fonctionnalisation de polymeres insatures—action du chloracetonitrile en milieu basique sur les organoboranes derives des polyalcadienes

Trialkylboranes react with chloroacetonitrile in the presence of potassium 2.6-di-tert-butylphenoxide to give nitriles. This reaction, coupled with hydroboration by 9-bora-bicyclononane, allows selective cyanomethylation of alkenes. The application of this reaction to trialkylborane structures derived from alkene structures of polyisoprenes and polybutadienes has been considered. In order to determine the polydienic structures best suited for this reaction, we have studied model molecules of 1.4 and 1.2 polybutadienes and of 1.4 and 3.4 polyisoprenes and then applied the process to the corresponding polymers.     

La reaction de Wittig-Horner en milieu heterogene IX. Bis aldolisation des phosphonates a partir des dialdehydes aliphatiques en milieu aqueux peu basique. Synthese de cyclenols fonctionnels.

Aqueous solutions of glutaraldehyde and succinaldehyde give respectively improved yields of 1-functional 6-cyclohexenols and 5-cyclopentenols, when subjected to WITTIG-HORNER reaction in water at room temperature, with potassium carbonate as a base.     

Mecanisme d'hydrolyse en milieu basique aqueux d'esters allophaniques,modeles de carboxybiotine

This work is dealing with basic hydrolysis in water of allophanic esters as possible models of carboxybiotin. A complex mechanism is involved likely due to competition of nucleophilic attack on the two carbonyl groups of the substrate. The rate of hydrolysis is significantly increased by metallic cation (Mg⁺⁺), a specific effect which allows to consider characterization of selectivity of bond breaking between nitrogen and carboxylate group with other nucleophiles.     

Etudes dans le domaine de l'autoxydation—III : L'autoxydation de cyclopentadienones en milieu basique

Even though they do not possess an acidic hydrogen, cyclopentadienones (cyclones) may be autoxidized under basic conditions. The mechanism involves in the first step a Michael addition of base, giving a carbanion which is autoxidized. The resulting lactol undergoes a fragmentation reaction with base, confirming the proposed structure.     

Action des phenylacetonitriles α-substitues sur les tetrahalomethanes en milieu basique: Mecanismes de l'halogenation et de la duplication

Carbanions of substituted phenylacetonitriles are halogenated by carbon tetrachloride or carbon tetrabromide, and also converted into symmetrically-substituted succinonitriles. The halogenation occurs via an ionic process, and the formation of succinonitriles via a radical process, essentially a no-chain mechanism in the case of diphenylacetonitrile anion, confirmed by the course of the reaction of p-nitrobenzylchloride on the diphenylacetonitrile anion.     

Elimination de groupements arysulfonyles en milieu heterogene

A new synthesis of Vitamin A using sulphones has been achieved. The most important step is the elimination of sulphinic acid (potassium alkoxides in a heterogeneous medium are the best reagents) and subsequent formation of the polyenic chain.     

Contribution a l'etude de l'oxyde de cadmium en milieu alcalin

Résumé L'étude de la réaction de NaOH sur CdO ou Cd(OH)₂ a nécessité de reprendre celle des courbes ATG et ATD de NaOH à différents stades de pureté. Ceci a permis, en particulier, de préciser l'existence de l'eutectique ternaire NaOH-Na₂O-Na₂CO₃ dans les mélanges réactionnels traités, d'exclure la possibilité de la présence de peroxyde. Le produit de la réaction, obtenu avant 130°, est plus stable à la chaleur que NaOH. Son spectre IR est compatible avec l'existence d'un hydroxocadmiate de sodium.

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The investigation of the reaction of sodium hydroxide with CdO or Cd(OH)₂ made necessary some studies on the DTA and TG curves of sodium hydroxide samples of different purities. These studies have evidenced the formation of a ternary eutectic NaOH-Na₂O-Na₂CO₃ in the heat-treated reaction mixtures, and have also shown that no peroxide is present. The product of reaction obtained below 130° had a greater thermal stability than NaOH. On the basis of the infrared spectrum the existence of a sodium hydroxocadmiat can be assumed.

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Zusammenfassung Die Untersuchung der Reaktion von Natriumhydroxyd mit CdO oder Cd(OH)₂ erforderte eine neue Untersuchung der DTA und TG Kurven des NaOH von verschiedenem Reinheitsgrad. Dies bewies das Vorhandensein eines ternären Eutektikums NaOH-Na₂O-Na₂CO₃ in den behandelten Reaktionsgemischen, weiterhin, daß kein Peroxyd gegenwärtig ist. Das vor 130° erhaltene Reaktionsprodukt besitzt höhere thermische Stabilität als NaOH. Aufgrund der infraroten Spektren darf die Existenz eines Natriumhydroxocadmiats angenommen werden.

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NaOH CdO Cd(OH)₂ . NaOH-Na₂O-Na₂CO₃ . , 130°, , NaOH. - .

     

Hydrodimerisation electrochimique de cetones aromatiques encombrees en milieu aprotique et en presence de chlorure de chrome

The electrochemical reduction of hindered aromatic ketones which are difficult to reduce alone, can be achieved in an aprotic medium (DMF) on a mercury pool cathode, in presence of Cr(III) chloride, at the reduction potential or the Cr(II)/Cr(0) system, but at a less negative potential than that of the ketone itself. There is selective hydrodimerisation into an α-glycol, with total lack of polymerisation. With dissymetric ketones, the dl-diastereoisomers of the diols are produced. The effect of chromium is due either to the reduction of a Cr-ketone complex or to the reduction of the ketone by a film of colloidal chromium on the electrode surface.     

Contribution a l'étude de l'oxyde de cadmium en milieu alcalin

Résumé La thermogravimétrie et l'analyse thermique différentielle montrent que l'oxydation du cadmium à l'air est négligeable jusqu'à 400°, tandis qu'en présence de peroxyde de sodium de soude ou de peroxyde de baryum, elle est totale mais que l'agent oxydant est uniquement l'oxygène de l'air. Le calcul de la chaleur de réaction à partir de la mesure de l'air du pic d'ATD correspondant fait conclure à la seule formation de l'oxyde de cadmium, le pic de fusion étant utilisé comme référence.

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Thermogravimetric and differential thermoanalytical investigations have shown that the oxidation of cadmium in air is negligible up to 400°. In the presence of sodium peroxide, barium peroxide or sodium hydroxide complete oxidation takes place, the aerial oxygen acting as the only oxidizing agent. The heat of reaction, calculated from the DTA peak area using the peak corresponding to the melting of the sample as reference, indicated that exclusively cadmium oxide was formed.

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Zusammenfassung Thermogravimetrische und differentialthermoanalytische Untersuchungen zeigten, daß die Oxydation des Kadmiums in Luft bis zu 400° vernachlässigbar ist. In Gegenwart von Natriumperoxyd, Bariumperoxyd oder Natriumhydroxyd tritt vollständige Oxydation ein. Als Oxydationsmittel wirkt jedoch ausschließlich der Luftsauerstoff. Die aus der Messung der DTA Spitzenfläche erfolgte Berechnung der Reaktionswärme, wobei die dem Schmelzen entsprechende Spitze als Referenz diente, wies auf die alleinige Bildung von Kadmiumoxyd hin.

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, 400° . , , . , TA, , , .