Addition thermique des iodo-1-perfluoroalcanes sur les perfluoroalkylethylenes

We have undertaken a study of the thermal addition of 1-iodo-perfluoroalkanes (C_nF_{2n + 1}I where n = 4, 6, 8) to perfluoroalkylethylenes (C_nF_{2n + 1} CHCH₂ where n = 4, 6, 8). Structures of the reaction products were established through spectroscopic or chemical identification and the optimal conditions for obtaining 1,2-bis(perfluoroalkyl)iodoethanes determined. The good yields thus obtained demonstrate the utility of this method of perfluoroalkylation.     

Action des composes organomagnesiens sur les pyrones-2-VIII : Identification des intermediaires reactionnels

The correlation between the structure of the intermediates and final products during the reactions of the methylmagnesium iodide with several 2-pyrones could be established by intercepting the intermediates before hydrolysis using methyl iodide in HMPT. In this way it was possible to show that these reactions either involve the formation of the dihydropyranol or the unsaturated E-ketol depending on the stereochemistry of these intermediates. The presence of cyclic magnesium alkoxides was established so proving the existence of a tautomeric “ring-chain” equilibrium before hydrolysis.     

Action des derives du phosphore tricoordonne sur les germanones et germathiones: Oxydation des phosphines

Desulfuration reactions of germadithiolanes by trialkylphosphines lead to germathiones via intermediate germathietanes. The formation of germylenes finally observed arises from reduction of germathiones by trialkylphosphines. Analogous reduction reactions of germanones by three coordinated linear and cyclic phosphorus compounds are also described.     

Action du methyltri(n-butyl)fluorophosphorane sur les halogenures et les sulfonates d'alkyle

Monofluorophosphoranes R₃MePF are used in exchange reactions to prepare monofluorinated organic compounds. Tri(n-butyl)methylfluorophosphorane (n-Bu₃MePF), easily available, is the most reactive. In solvents of low polarity or even in non-polar solvents, it reacts at ?70° with alkyl sulphonates and halides activated by ester, ketone, or ether functions. Thus, fluorinated epoxides can be obtained directly by exchange from their chlorinated or brominated homologues.     

Influence de la structure sur les proprietes mesomorphes des polyesters—I

A new series of thermotropic liquid crystalline polymers has been synthesized. Mesogenic elements are separated by flexible spacers —(CH₂)_n— in the backbone. The thermal properties of these polymers are analogous to liquid crystals.     

Synthese de cetones aliphatiques encombrees : Action des organolithiens sur les dimethyl-4,4 oxazolines-2. Addition des organometalliques sur les sels de dimethyl-4,4 oxazolinium-2

α,α-Disubstituted ketones result from the reaction of organolithium compounds with substituted 4,4-dimethyl-2-oxazolines, 4, after hydrolysis of the intermediate enamine. Alkylation of the latter also permits the synthesis of α,α,α-trisubstituted ketones. α,α-Disubstituted ketones have been prepared by addition of organometallic reagents to 4,4-dimethyl-2-oxazolinium salts, 6. The efficiency of this method has been compared to that of other currently used methods.     

Action des molecules organiques sur les composes d'insertion de metaux alcalins dans le graphite

Resume Les bases de Lewis (Tétrahydrofuranne, Diméthyl-2,5 tétrahydrofuranne, Diméthoxyéthane, Diméthyl éther du triéthylène glycol, Dioxanne, Triéthylamine, N,N,N,N tétraméthyl éthylène diamine) pénètrent dans les composés d'insertion de métaux alcalins dans le graphite (LiC₁₂, KC₃₆).Des changements de stades et de nouvelles distances interplanaires sont observées par diffraction des rayons X. En général, les nouveaux composés lamellaires obtenus comportent plusieurs phases, et sont comparables aux composés ternaires obtenus par synthèse directe.Ces solvates peuvent contenir jusqu'à deux molécules de solvant par cation, leurs stabilités thermiques peuvent donner des informations sur les pouvoirs complexants des solvants basiques.

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Lewis bases (tetrahydrofuran, 2,5-dimethyltetrahydrofuran, dimethoxyethane, triethyleneglycol dimethyl ether, dioxane, triethylamine, N,N,N,N-tetramethylethylenediamine) penetrate into graphite inclusion compounds of alkali metals (LiC₁₂, KC₃₆).Stage changes and new interlayer distances are inferred from the X-ray diffraction data. Generally these lamellar compounds have several phases. They are similar to those made by direct synthesis.These solvates can contain up to two solvent molecules for one cation and the complexing powers of the solvents can be inferred from their thermal stabilities.

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Zusammenfassung Die Lewis-schen Basen (Tetrahydrofuran, Dimethyl-2,5-Tetrahydrofuran, Dimethoxyäthan, Triäthylenglykol Dimethyläther, Dioxan, Triäthylamin, N,N,N,,N-Tetramethyl-Á thylendiamin) dringen in die Insertionsverbindungen der Alkalimetalle des Graphits ein (LiC₁₂, KC₃₆).Phasenveränderungen und neue interplanare Entfernungen wurden mittels Röntgendiffraktion beobachtet. Im allgemeinen bestehen die erhaltenen neuen lamellaren Verbindungen aus verschiedenen Phasen und können mit den durch direkte Synthese erhaltenen Ternärverbindungen verglichen werden.Diese Solvate können je Kation bis zu zwei Molekülen Lösungsmittel enthalten, ihre Thermostabilitäten können Informationen über das Komplexierungsvermögen der basischen Lösungsmittel geben.

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( , 2,5- , , , , , N,N,N,N ) - (LiC₁₂, KC₃₆). - . , , . . .

     

Etude des reactions des diazoderives avec les cycloimmonium ylures-I : Action des sels de diazonium sur quelques pyridinium - ylures

The synthesis of cycloimmonium salts of the type $\text{7}$, $\text{8}$ and the corresponding cycloimmonium ylides $\text{9}$, $\text{10}$ are reported. In the reaction with diazonium salts $\text{11}$, $\text{12}$ the pyridinium monosubstituted carbanion ylides $\text{9}$, $\text{10}$ give the pyridinium disubstituted carbanion ylides $\text{17}$ – $\text{20}$. These are new types of isolable stable ylides. The synthesis involves the formation “in situ” of ylides $\text{9}$, $\text{10}$ which are bonded by their nucleophile ylide carbon atom to the nitrogen atom in diazonium salts. The intermediat formation of cycloimmonium salts $\text{13}$ – $\text{16}$ must be accepted. The structures of all compounds presented in this paper have been established by using elementary analysis, IR and ¹H-RMN spectra.     

Addition conjuguee des α, ω-bis(bromomagnesio)alcanes sur les coumarines

Reactions of 1,4-bis(bromomagnesio)bütane and 1,5-bis(bromomagnesio) pentane with coumarin and 6-methylcoumarin gave a mixture of 1-(o-hydroxystyryl)cycloalkanol and 4-alkyl-3,4-dihydrocoumarin. A large difference in product distribution was observed between the two bifunctional reagents. Annelation was favored by the use of 1,4-bis(bromomagnesio))butane, whereas conjugate addition was observed with 1,5-bis(bromomagnesio)pentane and even In the use of 4-methylcoumarin.     

Action des organo-magnesiens sur la thiobenzophenone

Grignard reagents react with thiobenzophenone to give mainly the compound resulting from addition of the' organic radical to the sulfur atom. Addition to carbon, double addition both to sulfur and to carbon, and formation of tetraphenylthiiranne are also observed. The stable alkylthiodiphenylmethyl radical has been detected in the reaction medium. A mechanism is proposed to account for the various reactions.     

Action des isocyanates sur les benzisothiazol-2,1 ones-3 (1H) et sur les thiadiazol-1,2,4 ones-5: Un nouveau réarrangement avec extrusion de l'atome de soufre

The reaction of isocyanates with 2,1-benzisothiazo1-3-(1H)ones and on 1,2,4-thiadiazo1-5-(4H)ones was investigated. With a stoichiometric amount of organic base the reaction resulted, in both cases, in the incorporation of two atoms of the isocyanate into the heterocycle and concomitant extrusion of the sulphur atom.     

Action des réartif's électrophiles sur les hydroxy-3 thiadiazoles-1,2,4

Electrophilic reagents may react either with the hydroxyl group in position 3, or with the 2-nitrogen atom of 3-hydroxy-1,2,4-thiadiazoles (1). Those reagents which can be considered as “hard” (acid chlorides) result mainly in the type of derivative 2 Isocyanates and acid anhydrides, however, which furnish specifically derivatives of the second type, 3, behave like “soft” reagents.     

Influence des interactions de torsion dans les reactions d'addition sur les cyclohexanones. interpretation generale du deroulement sterique des reactions des hydrures ou des organomagnesiens sur les cyclohexanones

The addition of allyl and butenyl Grignard reagents to 4-t-butylcyclohexanone affords a greater proportion of the equatorial alcohols than is formed from the corresponding saturated Grignard reagents (propyl and s-butyl). In the case of the allyl Grignard reagent, the equatorial alcohol is the major product. Lithium aluminium hydride reduction in ether at 0° of cis and trans 4-t-butyl-2-methyl-cyclohexanone and cis and trans 4-t-butyl-2-chlorocyclohexanone affords mixtures of epimeric alcohols in ratios of equatorial to axial OH 8.4:1, 20:1, 4.2:1, and >70:1 respectively. These results fit in well with the view that polar interactions and torsional strain are both important in determining the steric course of the reaction.     

Action des composes organomagnesiens sur les pyrones-2—IX : Etude des différentes voies réactionnelles

The formation of the dihydropyranol 15 during the synthesis of the 6-hydroxy-4-heptene-2-one (Z) 14 indicates the possibility of an equilibrium between ketols (Z) 5 and pyranols 6. This equilibrium lies well to the side of the pyranol. It might be argued that the dihydropyranol compounds prepared from 2-pyrones and Grignard reagents can be derived from the Z ethylenic ketols.Criteria for the reaction scheme are provided by the stereoselectivity of intermediates in agreement with MNDO (modified neglect of diatomic overlap) calculations.A brief discussion of the present knowledge on the different reaction schemes concerning the reaction of Grignard reagents with 2-pyrones is added.