Etude des formes fermées et ouvertes de spiropyrannes benzothiazoliniques en RMN 13C et 1H par transformée de Fourier

Benzothiazolinic spiropyrans, merocyanines and photomerocyanines, thermally stabilised to a high degree, have been studied by means of Fourier transform ¹H and ¹³C NMR. The results show the polarity of open forms such as merocyanines and photomerocyanines, their trans configuration, the alternation of the electronic density on the dimethine bridge between the ‘benzothiazolinic’ and ‘phenolate’ part of these molecules, and also a favoured configuration when photomerocyanines have an alkoxy or aryloxy group on the 3 position.     

Conformation et Spectrometrie de RMN. III. Spectres 13C de Diméthylamino Cyclanols et Dérivés

The ¹³C NMR spectra of 2-dimethylaminocyclohexanols and the four trans-3-dimethylamino-2-decahydronaphtols are described. The gauche interactions allow precise estimation of chemical shifts for each carbon atom; thus, band attribution can be resolved without mistake. In the case of the cis and the trans diequatorial compounds, the conformational perturbations which we have suggested before are verified by our present measurements on the substituted carbon atoms. We also show effects on adjacent atoms, which were unobservable with the usual IR and ¹H NMR techniques.     

Controle analytique par spectroscopie infrarouge de la synthèse et de la pureté de spiropyrannes et mérocyanines benzothiazoliniques

Infrared spectroscopie studies of the synthesis and purity of benzothiazolinic spiropyrans and merocyanines. An i.r. spectroscopie study of benzothiazolinic spiropyrans and meroXXXyanines is described. The structures of the synthesized compounds (closed form or open form) can be characterized, their purity can be checked, and degradation products can be detected.     

Sur la synthèse d'alkoxy-2 nitro-3 2H-chroménes

2-Alkoxy-3-nitro-2H-chromenes have been obtained by the reaction of β-nitroacetaldehyde dialkyl acetals with some salicylic aldehydes in the presence of triethylamine p-toluene sulfonate.     

Etude de composés d'addition des acides de Lewis XXVIII. Constantes de Hammett et vibration carbonyle des composés formés par TiCl4 et SbCl5 avec des chlorures de benzoyle parasubstitués

The adducts of benzoyl chlorides p-substituted by CH₃O? , CH₃? , and H? with the electronic acceptors SbCl₅ and TiCl₄ have been prepared, and the IR. absorption spectra of the solid products studied.     

Etude theorique (cndo/s) des etats excites et des transitions electroniques de 2h-chromenes representant la partie responsable de l'ouverture photochimique de spiropyrannes

The excited states and electronic transitions of some 2H-chromenes (considered responsible for photochemical opening of photochromic spiropyrans) have been studied. The relative positions of nπ^* and ππ^* singlet and triplet energy levels of these compounds allow a satisfactory interpretation of their optical properties. Also highly localized electronic charge transfers are demonstrated in the case of 2H-chromenes substituted by a nitro group.     

Etude par Spectrométrie de Masse de Silanes et de Stannanes Aromatiques

The mass spectra of six compounds of the type Et₃Si? C₆H₄? ZR_xR_3?x (R=Et, R′ = CI, Z = Si, Sn) have been measured. The fragmentation patterns can be interpreted on the basis of an ionized hexa-1,3-diene-5-yne intermediate.     

Dérivés de désoxy-hydroxylamino-sucres et radicaux libres diglycosylnitroxydes correspondants. Communication préliminaire

Deoxy-hydroxylamino-sugar Derivatives and Corresponding Diglycosylnitroxides Radicals A number of sugar aldonitrones, including C,N-diglycosylnitrones, and ketonitrones have been treated with Grignard reagents or cyanide anion leading to the corresponding deoxy-hydroxylamino-sugars. On oxidation (air, H₅IO₆ or PbO₂), these compounds gave the corresponding nitroxide radicals whose ESR. spectra are reported. Analogues of disaccharides, in which the interglycosidic O-bridge is replaced by a hydroxyimino group, have been obtained by reacting a partially blocked sugar bearing a free hemiacetal group either with a deoxy-hydroxylaminosugar or with hydroxylamine, followed by reaction with an aldehydosugar and a reducing agent (NaBH₄). These reactions represents the key synthetic steps for the oligosaccharide-type synthesis of deoxy-hydroxyimino-oligosaccharides. Their oxidation yielded the corresponding nitroxide radicals whose ESR. spectra gave information on the conformation about the ‘interglycosidic’ bridge. This type of compounds should constitute useful spin markers for biological studies.     

Le diméthyl- et le diéthyl-tétracarbonylosmium Synthèse et réactivité

The sodium salt Na₂[Os(CO)₄] has been obtained in high yields by the reduction of either OsH₂(CO)₄ or Os₃(CO)₁₂ with sodium sand in the presence of catalytic amounts of 2, 2′-bipyridyle. The reaction of Na₂[Os(CO)₄] with alkylating agents such as methyl and ethyl iodide produces OsR₂(CO)₄ (R = CH₃, C₂H₅). NMR. and IR. spectra indicate a cis-octahedral structure of symmetry C_2v for these new alkyl compounds. Bromine breaks one osmium-carbon bond in cis-Os(CH₃)₂(CO)₄ to give cis-OsCH₃Br(CO)₄, whereas in cis-Os(C₂H₅)₂(CO)₄ both ethyl groups are easily displaced by bromine to give cis-OsBr₂(CO)₄. Under CO pressure and at elevated temperature cis-Os(CH₃)₂(CO)₄ is converted to Os(CO)₅ and ethane. With cis-Os(C₂H₅)₂(CO)₄ two CO are inserted in osmium-carbon bonds to give . NMR. and IR. data suggest a cis-configuration for this derivative and the possibility of the presence of rotational isomers.     

Interactions Intramoleculaires—X: Etude par RMN des Équilibres Conformationnels de Cyclohexènes Monosubstitutés en 4 et du Dicyano-1,2 Cyclohexane trans

The conformational free energies of CN, Cl and COOC₂H₅ substituents have been evaluated from the PMR spectra of 4-substituted 3,3,6,6-d₄-cyclohexene. The PMR spectra of trans-1,2-dicyano-3,3,6,6-d₄-cyclohexane permit the conformational equilibrium (in different solvents) and the gauche diequatorial interaction energy between the two CN substituents to be estimated.     

Etude par spectrométrie de masse de l'ionisation de benzonitriles,de phénylacétonitriles et de N,N-diméthylanilines substitués

Molecular ionization potentials for series of compounds of the type X? C₆H₄? CN, X? C₆H₄CH₂? CN and X? C₆H₄? N(CH₃)₂ have been measured using the retarding potential difference technique (RPD. technique). The effect of the various substituents X is better correlated through the electrophilic Brown σ_p⁺ constants than through Hammett's σ_p values. No meta-para orientation effect is observed. For all the disubstituted phenyl compounds studied, the effect of the second substituent is affected by the electron-releasing power of the original substituent. Ionization potentials calculated by using the semi-empirical method of equivalent orbitals are in good agreement with the experimental values.     

Schwingungsspektroskopische Untersuchungen an Sulfamid-Einkristallen

The infrared (300 K) andRaman (300 and 90 K) spectra of single crystals of sulfamide are recorded. In addition theRaman spectra of the deuterated and N¹⁵-substituted polycrystalline sulfamide are measured. A vibrational assignment based on these data and a normal coordinate analysis is proposed. Lattice bands and factor group splittings are discussed.

     

Étude structurale de spiropyrannes benzothiazoliniques par détermination expérimentale et théorique des moments dipolaires

For the conformational study of a series of benzothiazolinic spiropyrans, experimental and theoretical (E.H.T. method) dipole moments have been checked.The energetic data of the semi-empirical calculations for the eight possible spiropyrannic conformations (four limit conformations for each enantiomer) and the comparison between experimental and calculated dipole moments fit quite well, and allow an interesting approach to the conformation of these molecules, in spite of their complexity.     

Etude théorique et expérimentale des spectres électroniques d'absorption de cyclohepta[b ou c] thiophénones-6 et des hydroxy-5 cyclohepta[b ou c] thiophenones-6

Electronic spectra of cyclohepta[b or c]thiophen-6-ones and 5-hydroxycyclohepta[b or c]thiophen-6-ones are computed by C.N.D.O./S Jaffé method extended to the third long period. Theoretical results obtained account satisfactorily for experimental data. A new interpretation of the electronic spectra of tropone is favoured.     

Complexation du 2‐[(5‐méthyl­pyrazolyl)méthyle]benzimidazole par les chlorures de cuivre et de cadmium

The structures of dichloro{2‐[(5‐methyl‐1H‐pyrazol‐3‐yl‐κN²)methyl]‐1H‐1,3‐benzimidazole‐κN³}copper(II), [CuCl₂(C₁₂H₁₂N₄)], and di‐μ‐chloro‐bis(chloro{2‐[(5‐methyl‐1H‐pyrazol‐3‐yl‐κN²)methyl]‐1H‐1,3‐benzimidazole‐κN³}­cadmium(II)), [Cd₂Cl₄(C₁₂H₁₂N₄)₂], show that these compounds have the structural formula [ML(Cl)₂]_n, where L is 2‐[(5‐methylpyra­zolyl)methyl]benzimidazole. When M is copper, the complex is a monomer (n = 1), with a tetrahedral coordination for the Cu atom. When M is cadmium (n = 2), the complex lies about an inversion centre giving rise to a centrosymmetric dimer in which the Cd atoms are bridged by two chloride ions and are pentacoordinated.     

Réactions de Friedel et Crafts de dérivés aromatiques sur les composés dioxo-1,4,2,3-non saturés. IV. Réactions des hydroxy-5-ouchloro-5-diméthyl-3,5- ou diméthyl-4,5-dihydro-2,5-furannones-2

Friedel-Crafts reactions of aromatic derivatives with 1,4-dicarbonyls 2,3-éthylenic compounds. Part IV. Reactions of 5-hydroxy or 5-chloro 3,5-dimethyl or 4,5-dimethyl 2 (5 H) furanones We studied the Friedel-Crafts reactions of 2-(5H)-furanones. In the presence of sulfuric acid and of an aromatic derivative, 5-hydroxy- or 5-chloro-5-methyl-2-(5H)-furanones with one methyl group either in the 3 position, or in the 4 position generally give the corresponding 5-aryl-2-(5H)-furanones, while with aluminium chloride, it is possible to obtain, when a reaction takes place, isomeric 1H-indenecarboxylic acids. However, in a particular case, an addition to the substrate's double bond is observed. The 3-aryl-5-hydroxy-tetrahydrofuran-2-one obtained is methylated in two ways and gives either a cyclic product, or a linear one. In two cases tautomerism between 1H-1-indenecarboxylic acid and 1H-3-indenecarboxylic has been shown by ¹H-NMR.     

Sur la synthèse de quelques furochromènes,analogues pharmacochimiques de la xanthylétine et de la séseline

Some furochromenes substituted at the 2-position by an electron-attracting group were obtained starting from ortho-hydroxyformyl derivatives of 2,2-dimethyl-2H-chromene following various processes which are indicated. These new furochromenes are pharmacochemical analogues of some natural pyranocoumarins, and as such they are potential photosensitizers.     

Détermination par RMN 1H et 13C des Couplages J(CH) et J(CC) dans des Monomères Precurseurs de Lignine: Vanilline,Férulate d'Ethyle et Alcool Coniférylique Sélectivement Enrichis en 2H et 13C

Some monomer model compounds of lignin have been selectively ²H and ¹³C labelled: vanillin, ethyl ferulate, coniferyl alcohol and ethyl hydrogen malonate. Deuterium isotope effects on the ¹³C chemical shifts in [formyl-²H]vanillin, [5-²H]vanillin and [α,α,5-²H₃]coniferyl alcohol made the unambiguous assignment of the aromatic ¹³C signals possible. Absolute ^1,2,3J(CC) values have been determined on ¹³C spectra of [formyl-¹³C]vanillin, and of ethyl ferulate and coniferyl alcohol in which the vinylic C-γ and C-β carbons were ¹³C enriched. It has been possible to measure ⁴J(C?O, C-4) in vanillin and ⁴J(C-γ, C-4) in ethyl ferulate. The determination of ^1,2,3,4J (CH) absolute values was done by means of gated decoupled ¹³C spectra of the non-labelled compounds. When second order effects made the use of this technique impossible we determined certain J(CH) values and their signs either by analysing the ¹H NMR spectra of ¹³C labelled coniferyl alcohol [²J(C-β, H-γ), ²J(C-β, H-α), ²J(C-γ, H-β), ³J(C-γ, H-α)] or by a double irradiation experiment on the 250 MHz ¹H NMR spectrum of ethyl [β-¹³C] ferulate [for ²J(C-β, H-γ)].     

Etude de composés d'addition d'acides de Lewis. XXXVI [1] Composés d'addition de l'anthraquinone-9, 10 et de l'anthrone avec divers acides de Lewis

Solid stoichiometric adducts of 9, 10-anthraquinone with SbCl₅, ZrCl₄, TiCl₄ SnCl₄, AlCl₃, have been prepared. The very important lowering Δω of the IR. carbonyl frequency, ranging from ?175 cm^?1 for SbCl₅ to ?117 cm^?1 for SnCl₄, shows that the acceptor is linked by a dative bond to the carbonyl oxygen atom acting as a donor; an assignment of most of the fundamental IR. frequencies is proposed for anthraquinone and the mentioned adducts. Similar assignments and interpretation have been made for anthrone and its solid adduct with SbCl₅, ZrCl₄, TiCl₄, SnCl₄, AlCl₃ and ZnCl₂, where the C?O lowerings range from ?164 cm^?1 for SbCl₅ to ?97 cm^?1 for ZnCl₂.