Complexes macrocycliques des lanthanides: Stabilité et comportement électrochimique dans le méthanol et le carbonate de propylène

Macrocyclic Complexes of Lanthanides: Stability and Electrochemical Behaviour in Methanol and Propylene Carbonate The stabilities of the 1:1 complexes of the trivalent lanthanides with the diazapolyoxamacrocycles (2.1.) and (2.2.1.) in anhydrous methanol and propylene carbonate have been determined at 25°, by competitive potentiometric methods using H⁺ or Ag⁺ as auxiliary cations, with Et₄NClO₄ as supporting-electrolyte. Additional data are also reported for the crown ethers 15C5 and 18C6 in propylene carbonate. It is shown that the diazapolyoxamacrocycles are much stronger complexing agents for trivalent lanthanides than macrocyclic polyethers, and that the bicyclic (2.2.1.) cryptates are more stable than the monocyclic (2.1.) complexes. With increasing atomic number of the lanthanides, the stability increases with diazapolyoxamacrocycles and decreases with cyclic polyethers. The electrochemical reduction of the trivalent samarium and europium cryptates has been investigated by polarography on a dropping Hg-electrode, in water and methanol. In both solvating solvents, the +2 oxidation states of the cations are stabilized by complexation.     

Action du monoxyde d'azote sur le trichloréthylène et sur le tétrachloréthylène

The Action of Nitrogen Monoxide on Trichloro-and Tetrachlor-Ethylene . Under the sun light and at room temperature nitric oxide reacts with trichlorethylene and tetrachlorethylene giving monomer nitroso nitrated compounds. These compounds can also be obtained through reaction of dinitrogen trioxide with trichlorethylene and tetrachlorethylene. The nitrating and oxidizing properties of nitric oxide can be considered through these reactions: – Trichlorethylene leads to: pentachlorethane,1,1,1,2-tetrachlor-2-nitroethane, dichloracetic acid and 1,1,3,3-4-pentachloro-4-nitro-1-butene: CO₂ and CO are also observed. –Tetrachlorocthylene gives : hexachlorethane, tetrachloro-2pentaclorethyl-1,2-oxazetidine; carbon tetrachlorid and trichloracetylchlorid arc obtainetl in very little yiclcl. These results prove that oxidizing cleavage may occur. Kitric oxitl reacts giving nitrogen as main gazcous product, prouved by gas liquid chrornatography.     

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a pentalène. IX—etude par RMN de l'équilibre azide/tetrazole dans le cas du tetrazolo [5,1-b] benzothiazole

Azido-tetrazole equilibrium is observed in the case of a solution of tetrazolo [5,1-b] benzothiazole in CDCl₃, using proton magnetic resonance at 250 MHz. Analysis of the spectra obtained yields the chemical shifts and the coupling constants of the two tautomeric forms.     

Action du chlorure de nitrosyle sur le trichloréthylène et sur le tétrachloréthylène

Nitrosyl chloride is only chlorinating in darkness and above 100°. In the sun light and at room temperature it reacts as a chlorinating, nitrosating, nitrating and oxidizing agent. With trichlorethylene in fact pentachlorethane 1,1,1,2-tetrachloro-2-nitrosoethane, 1,1,1,2-tetrachloro-2-nitroethane, dichloracetic acid and a compound of empirical formula C₄H₂Cl₅NO₂ are obtained. Tetrachloroethylene carried to hexachlorethane, pentachloronitrosoethane and tetrachloro-2-(pentachlorethyl)-1,2-oxazetidine. Introduced nitrosyl chloride provided nitrogen monoxide prouved by gaz chromatography. This monoxide reacted afterwards to give nitrogen which is the single nitrogenous gazeous compound. Carbondioxide is a minor component of the gaz.     

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a pentalène. XXXII. Recherches dans la série du pyrazolo[1,5-a]benzimidazole

The aromaticity of a 3a-azepentalene derivative, the 2-methyl-pyrazolo[1,5-a]benzimidazole, has been studied by comparison of its chemical reactivity with those of a model compound, the l-phenyl-3-methyl-5-aminopyrazole. The mono- and di-protona-tion, alkylation, quaternization, formylation, acetylation reactions and the behaviour of the N-acetyl derivatives have been investigated. The conclusion favours a strongly polarized aromatic structure.     

Etude par RMN 13C à 62,89 MHz des branchements éthyles dans les copolymères ethylène-butène et polyéthylène basse densité

Carbon 13 nuclear magnetic resonance spectra (at 62,89 MHz) were obtained for a series of branched heavy alcanes (12-ethyl tricosane, 11,20-diethyl tricontane, 11,18-diethyl octacosane, 11,17-diethyl heptacosane, 11,16-diethyl hexacosane, 9,12-diethyl heneicosane, 5,7-diethyl docosane, 6,7-diethyl docosane, 2 éthyl-hexyl-12 tricosane), which provide a model set for describing the ethyl branched sequences in ethylene butene copolymers and low-density polyethylene (LDPE). For ethylene-butene copolymers we do not detect any head-to-head polymerization of butene as reported recently (the existence of a 1,2-ethyl pair has not been confirmed by the low-field signal at 41,3 ppm), but only isolated ethyl and 1-3-diethyl branches. The three peaks observed in the methyl region (broad signal) of the spectrum are assigned to butene centered triads, as opposed to branches in positions having different tacticities as reported earlier. Carbon 13 nuclear magnetic resonance spectra of high-pressure polymerized low-density polyethylene have been measured at 62,89 MHz. On the basis of Willbourn's double back biting mechanism, two kinds of complex branches, the 1,3-ethyl pair and 2-ethyl-hexyl, have been assigned. Finally, these results suggest that the ethyl branches in low-density polyethylene are not isolated branches.     

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a penlalène. VIII. Recherches dans la série du pyrazolo[3,2-c]-s-triazole

It has been shown that the reaction of β-ketoesters with 1,2-diamino-1,3,4-triazoles affords pyrazolo[3,2-c]-s-triazoles. These results induces us to propose a 7,8-dihydro-9H-s-triazolo[4,3–6]-[1,2,4] triazepin-8-one structure for the intermediate in this synthesis.     

Synthèse de flavones et de xanthones dans la série du benzo[4,5]thiophène

We describe the first synthesis of 2-arylbenzo[4,5]thieno-[2,3-b]pyran-4-one and of 2-arylbenzo [4,5] thieno [3,2-b] pyran-4-one, from benzo [4,5] thiophene and we have extended these cyclizations to obtain the heterocyclic analogs of the xanthones.     

Sur l'acylation des méthylfluorènes III [1]: Benzoylation et acétylation du méthyl-3-fluorène

Benzoylation and acétylation of 3-methyl-fluorene according to Friedel-Crafts in carbon disulfide with aluminium chloride yielded the corresponding 2-acyl derivatives. By oxidation the benzoyl derivative gave 2-benzoyl-9-oxo-fluorene-3-carboxylic acid, cychsable into the known 2,3-phthalyl-fluorenone. By Clemmensen reduction, the acetyl derivative gave 3-methyl-2-ethyl-fluorene.     

Etudes par spectroscopie dans l'ultra-violet et le visible, du fullerène C60 en solution dans le n-hexane ou adsorbé sur des solides diélectriques

Ultraviolet and visible spectroscopy studies of the fullerene C₆₀ melted in n-hexane or adsorbed on dielectric solids. Experiments of spectroscopy have been carried out, between the far ultraviolet and the near infrared, with pure C₆₀ or containing endohedral complexes rare gas atom-C₆₀, melted in n-hexane, and also pure C₆₀ adsorbed on surfaces of solids.Several phenomena have been observed: 1. a charge transfer due to the influence of interactions between the molecules of C₆₀ and surfaces of solids, yielding new transitions observed in the far ultraviolet ; and interpreted as super excited states of Rydberg type; 1.1. red and blue shifts for some transitions of adsorbed C₆₀, interpreted on the basis of attractive, or turned repulsive, dispersion forces; 1.1.1. emission processes for several transitions of adsorbed C₆₀, explained on the basis of a resonant coupling between these transitions and modes of the surface plasmon induced by the collective excitations of the C₆₀ molecule; this kind of process might be drawn to the Faraday instability in acoustics.     

Systemes aromatiques à 10 électrons π dérivés de l'aza-1-pentalène. I. Recherches dans la série du pyrazolo[3,4-d]-v-triazole

After the structure of the N-methyl derivatives has been established in an univocal manner, the reactivity of a pyrazolo-[3,4-d]-v-triazole derivative toward various methylation agents has been investigated. A structure is suggested for the N? NO and N? COR derivatives.     

Synthèses dans la série des bis-indéno-anthracènes,II [1] Le dihydro-9,16-bis-indéno[2.1-α; 1′,2′-c]anthracène

Starting from 3,3′-bi-indenyle and 1,4-naphthoquinone the title compound, III, has been synthesized in 3 steps (overall yield 54.6%).     

Synthèses dans la série des bis-indéno-anthracènes,III. Le dioxo-15,16-dihydro-15, 16-bis-indéno[1.2-a;2′.1′-c]anthracène et le tétraoxo-5,10,15,16-tétrahydro-5,10,15,16-bis-indéno[1.2-a; 2′.1′-c]anthracène

The title compounds, a dioxo (XVIII) and a tetraoxoderivative (VI) of a new diindenoanthracene, are synthesized in several steps (overall yield 35 and 26%, respectively) starting from 2,3-dimethyl-1,4-diphenyl-butadiene-1,3 (VIII). The corresponding hydrocarbon could not be obtained by reduction.     

Synthèse et étude conformationnelle de dioxa-1,3 aza-9 spiro[5,5]undecanes

Synthesis of the new l,3-dioxa-9-azaspiro[5.5]undecane ring, was realized by the scheme represented in Figure 2. Butyro-phenones 6 posses neuroleptic activity similar to that of halo-peridol. The pharmacological activity was reported in another publication (2). Conformational study of l,3-dioxa-9-azaspiro-[5.5]undecanes shows the existence of four conformations A, B, C and D, which are shown in Figure 4. The existence of these conformations depends on the nature of the substituents R and R' on the dioxane ring. Thus, in the compounds where R ≠ H, R' = H, the four conformations are possible with a preponderance of A and B. If R and R' are different from H only the conformation A is present in 99% concentration. Lastly, when R = R' = H, the four conformations are possible with equal population for the couple A, B and the couple C, D; the first couple predominating. The presence of a fluorophenylbutyric moiety on the piperidine nitrogen does not seem to stereochemically modify the heterocyclic group.     

Participation π dans la solvolyse des diazocétones primaires. Communication préliminaire

In the acid catalyzed hydrolysis of 5,6-unsaturated diazoketones of suitable geometry (Ib, IIb, IIIb, IVb, VIb), participation of the double bond in the reaction of the diazonium ion is proved (a) by the formation of cyclisation products, and (b) in some cases by the acceleration of the rate determining S_N2 substitution process. In the case of VIb the substitution step is so much accelerated that the pre-equilibrium protonation step becomes rate determining (evidence: inversion of the kinetic solvent isotope effect).     

Analyse conformationnelle théorique des molécules de benzylidène-aniline, stilbène et azobenzène : Partie II. Résultats de la méthode PCILO et ajustement d''un potentiel empirique

A conformational study of the benzylidene-aniline stilbene and azobenzene isoelectronic molecules has been carried out by the PCILO method in terms of torsional angles, bond lengths and valence angles. Initially, the conditions of application of this method to highly conjugated molecules were defined. The optimized geometries are in good agreement with those determined in the gas phase. Furthermore the rotation around a Ф—N or Ф—C bond can be specifically related to the variation of the second-order correction to the energy. This term was used to adjust the torsional potential in an empirical method adapted to this kind of molecule and able to account for both theoretical and experimental results.     

Spectres photoélectroniques He(I) et He(II) du benzo[b]sélénophène et du benzo[b]tellurophène

He(I) and He(II) photoelectron spectra of benzo[b]selenophene and benzo[b]tellurophene The photoelectron spectra of benzo[b]selenophene ( 2 ) and benzo[b]tellurophene ( 1 ) have been recorded with He(I) and He(II) radiation and been compared to those of benzo[b]thiophene ( 3 ), benzo[b]furan ( 4 ), indole ( 5 ) and indene ( 6 ). The first four bands are correlated with π-orbitals, of which the highest occupied one is strongly localized on the heteroatom in the case of 1 . The results are in agreement with semi-empirical PPP-calculations.