Etude des fragmentations en spectrographie de masse de dithiolannes-1,3 substitués en 2 par des groupements insaturés

The mass spectra of the title compounds always show an intense molecular ion. Some fissions involve loss of the ethylenic group, while others are related to cleavage of the dithiolane ring, eventually followed by recyclizations involving the ethylenic chain, due to which resonance structures can be written. If a phenyl group is present in the ethylenic chain, the spectra are modified due to the formation of the very stable benzothiopyrylium ion.     

Etude de la fragmentation des alkyl-thiazoles en spectrographie de masse

The mass spectra of 27 mono-, di- and trisubstituted alkyl-thiazoles are reported and discussed. The predominant fragmentation is characterized by the loss of R²CN with formation of a thiiren-ion and the β-cleavage with respect to the cyclic double bonds.     

Etude en RMN du carbone 13 de dicoumarols substitués

The ¹³C n.m.r. spectrum of the bridge substituted dicoumarols are interpreted in order to obtain structural information for quantitative structure-activity relationships. The results are in agreement with those obtained by ¹H n.m.r. These dicoumarols exhibit double restricted rotation around both bridge bonds.     

Etude de cyclohexanediols par spectrométrie de masse

Low resolution mass spectra of cyclohexane-1,2-diols and of deuterium labelled cyclohexane-1,2-diols cis and trans have been measured. The results indicate that it is easy to differentiate between positional isomers and that the stereochemistry of cyclohexane-1,2-diols can be deduced from the mass spectra. In the 1,2-diols the elimination of water under electron impact occurs simultaneously in three ways: (a) between an OH group and a H atom in position 1,4, (b) between the two OH groups, (c) without participation of the II atoms of the OH groups. Difficulties encountered in deducing unambiguous fragmentation patterns are discussed.     

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.     

Heterocycles contenant du phosphore-XXI. Etude par RMP de déeriveés de l'oxazaphospholane-l,3,2: I-Analyse des spectres des composksés non substitués en 4 et 5.

The PMR spectra of the title 1,3,2-oxazaphospholane derivatives present an ABKLX pattern. The subspectral analysis of such a system shows that there are eight solutions. INDOR experiments permit the establishment of the energy diagram and the selection of the correct solution.     

Etude structurale en serie dihydro iso-indole par spectrographie : De l'utilisation des bandes de Bohlmann en ir

Reduction of substituted 6,11-diphenyldibenzo[b,f] diazocines [1,4] with diborane gave two non-fluorescent products identified as cis or trans dihydroisoindole 3. This structure was based on IR Bohlmann bands, and on mass-spectrometric data. An isoindole structure was attributed to fluorescent products.     

Etude par spectrométrie de masse de la fragmentation des cyclopentane-triols-1,2,3, des cyclopentane-tétrols et des cyclopentane-pentols

The mass spectra of the three cyclopentane-1,2,3-triols, six cyclopentane-tetrols and four cyclopentane-pentols stereoisomers have been studied. Complex processes, especially regarding the H₂O eliminations, were detected by extensive deuterium labelling.     

Etude par spectrométrie de masse du cyclopentanediol-trans-1,2

The electron impact induced fragmentation of trans cyclopentane-1, 2-diol has been investigated using derivatives specifically labelled with deuterium and high-resolution mass spectral data. The elimination of the elements of water from the molecular ion involves at least three mechanisms whose relative importance has been evaluated. A fragmentation scheme based upon metastable peaks and labelling is presented.     

Recherches dans la série des cyclitols XXXVII Etude par spectrométrie de masse

Low resolution mass spectra of cyclohexane-triols, -tetrols, -pentols and -hexols and of some of their deuterium labelled derivatives have been measured. The results indicate that for some geometrical isomers quantitative differences between ion intensities are significant, allowing to deduce the stereochemistry of the molecule from its mass spectrum. In all these compounds the electron impact induced elimination of water occurs mainly by interaction between OH groups. There is a correlation between the relative abundance of (M – H₂O)⁺ and (M ?2 H₂O)⁺ ions and the number of axial hydroxyls in the more stable conformation of the molecule. Difficulties encountered in deducing fragmentation patterns, and determination of number and position of deuterium atoms in the molecule of ms-inositol are discussed.     

Mécanismes de fragmentation en spectrométrie de masse par ionisation chimique. III—ions formés par cyclisation

Chemical ionization mass spectrometry of bifunctional organic molecules can induce fragmentation involving the formation of cyclic ions.     

Benzodioxines-1,4 disubstituées en position 2,3 par des groupements pharmacophores

2,3-Disubstituted 1,4-benzodioxines were prepared in six steps from 2-carboxy-1,4-benzodioxine. The α- and β-adrenergic blocking properties of these compounds were measured.     

Etude des volumes specifiques partiels de polystyrenes-modeles—Influence de la masse moleculaire et de la nature des groupements terminaux

It is well known that the apparent specific volume η₂ of a polymer may be expressed by the following relationship: $\text{η}{}_2\text{= η}{}_{\mathrm{m}}\text{+ K/}\text{M}{}_{\mathrm{n}}$ where M?_n is the number-average molecular weight of the polymer, η_m the specific volume of the infinite polymer, and K a constant. We have shown that this relationship is valid for low molecular weight polystyrenes ($\text{M}{}_{\mathrm{n}}\text{< 4·10}{}^4$) with different end-groups, independently of the nature of the solvent. The K values (and variations with the solvent and with the nature of the end-groups) may be predicted through simple calculations proposed here. We conclude that η_m does not represent the specific volume of the infinite polymer, since we observe a rapid decrease of η₂ for increasing M (when $\text{M}{}_{\mathrm{n}}\text{< 4·10}{}^4$). The decrease is much greater than expected from the relationship $\text{η}{}_2\text{= ? (1/}\text{M}\text{)}$.     

Etude par spectrographie d'absorption infra-rouge de quelques complexes aquoamminés du nickel

Résumé Un essai d'interprétation des spectres d'absorption infra-rouge, entre 200 et 4000 cm^–1, des sels de nickeloaquopentammine et de nickelo-diaquotétrammine a permis d'obtenir un aperçu sur la structure de quelques autres complexes du nickel. En particulier, l'étude du déplacement de la bande de vibration de déformation symétrique de l'ammoniac avec l'espèce chimique a servi à déterminer la pureté de sels de nickelohexammine d'après leurs spectres.

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Summary An interpretative study of the infra red absorption spectra, between 200 and 4000 cm^–1, of the salts of nickeloaquapentammine and of nickelo-diaquatetrammine has given an insight into the structure of several other nickel complexes. In particular, the study of the displacement of the vibration band of symmetric deformation of ammonia with the chemical species has served to determine the purity of salts of nickelohexammine from their spectra.

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Zusammenfassung Der Versuch einer Interpretation der Infrarotabsorptionsspektren von Aquopentamminnickelaten und Diaquotetramminnickelaten zwischen 200 und 4000 cm^–1 gab einen Überblick über die Struktur einiger anderer Nickel-komplexe. Insbesondere diente die Untersuchung der Verschiebung der symmetrischen Schwingungsbande zur Reinheitsbestimmung von Hexammin-nickelaten auf Grund ihrer Spektren.

     

Recherches sur le benzofuranne. LXII. Orientation de la nitration de benzofurannes substitués en 2 par un groupement électro-attracteur

Nitration of 2-acetyl-, 2-carbethoxy- and 2-cyanobenzofurans by nitric acid in acetic anhydride mostly succeeds on the 5 and 6 positions, and in some instances on the 4 position and possibly on the 7 position. Moreover, in the first two cases, the substituent     

Etude de la fragmentation par impact électronique en ions positifs et négatifs de dérivés nitrés de l'amino-2-benzothiazole

Study of Positive and Negative Ions Electron Impact Fragmentation of 2-Amino-benzothiazole Nitro Derivatives The positive and negative ions mass spectra of 2-amino-4,6-dinitrobenzothiazole ( 1 ), 2-amino-4-nitrobenzothiazole ( 2 ), 2-amino-6-nitrobenzothiazole ( 3 ) are reported and discussed. These compounds give an intense molecular ion and show interesting fragmentations in both positive and negative ions spectra. Specific ¹⁵N-labelling was used in order to confirm the fragmentation patterns.     

Recherches en série diazépine-1,4 et triazépine-1,2,4. XI—etude en spectrométrie de masse des fragmentations de triazépines-1,2,4

The mass spectra of eleven 1,2,4-triazepines with oxo, thioxo, methoxy and methylmercapto groups in the 3 and 5 positions are reported and analysed. Each of the five structures of the triazepine ring present is characterized by a particular group of fragmentations.     

Etude par spectrométrie de masse de la fragmentation du cyclopentènediol-3,5-trans

The decomposition modes of trans cyclopentene-3, 5-diol under electron impact have been studied on deuterium labelled analogues. Fragmentation mechanisms are proposed.     

Etude par spectrométrie de masse des cyclopenténols,cyclopentène-diols-3,4 et cyclopentène-triols-3,4,5

The mass spectra of cyclopentene-1-ol-3, -1-o1-4, those of cis- and trans-cyclopentene-3,4-diol and of the three stereoisomers of cyclopentene-3,4,5-triol have been studied. Decomposition modes based upon results obtained using deuterium labelled analogues are discussed.