Preparation d'homopolymeres du thietanne de masses moléculaires determinees

A study has been made of the polymerization of thietane by thiolates such as thia-3-pentane thiolate with sodium, potassium or tetraethylammonium as cation. The following solvents have been used: tetrahydrofurane, acetonitrile, hexamethylphosphorotriamide and dimethylsulphoxide. Such thiolates permit the preparation of homopolymers of thietane with specified molecular weights but it has not been possible to explain, in these reactions, the activity of sodium naphthalene at −78°. The relationship between number average molecular weight and intrinsic viscosity is given.     

Interactions intramoléculaires: XXIII—Constantes de couplage et interactions gauches avec un groupement t-butyle (cyclohexanones disubstituées 3, 4)

The ¹H NMR spectra of a series of cis and trans-3R,4 X-cyclohexanones (-2,2,6,6-d₄) are analysed. By comparison of their ³J coupling constants with those of cyclohexane homologues we obtain information about the chair–chair equilibrium constants for R = CH₃, X = CN, the chair structure of cis isomers with an equatorial t-butyl group, and a conformational heterogeneity with trans (CH₃)₃C and CN groups. This latter situation is analysed by means of a simplified but controlled Karplus relationship, on the basis of a mixture of two conformers; this involves a diequatorial chair and a boat form with a dihedral angle Φ₃₄ of about ?6°.     

Sur le calcul a priori des déplacements chimiques de 1H et de 19F

We propose a new method for calculating ¹H and ¹⁹F chemical shifts in saturated organic compounds. Results show that the shifts are a balance of several contributions and allow an evaluation of these effects: a diamagnetic contribution d(—?) proportional to the net charge ? of the electronic environment of the nucleus considered and paramagnetic contributions p_X of each of substituents, constant attached to the substituent X in any molecule. For both nuclei, d values were deduced from a theoretical calculation of the screen in the free atom. This method, using a restricted number of parameters obtained from experiment, lead to the observed chemical shifts with a mean accuracy of ± 0,32 ppm for ¹H and ± 11 ppm for ¹⁹F. Therefore this method gives a simple quantitative relation between chemical shift and structure from which precise indications about the origin of the contributions from neighbouring electronic surroundings can be obtained.     

Nouvelle méthode de dosage photométrique automatique des protéines dans le lait entier : Partie I. Bases théoriques et optimisation des principaux paramètres de la réaction

A new method for the spectrophotometric determination of the protein content of whole milk is proposed. The fat and caseins, which render the milk turbid, are dissolved rapidly and completely by addition of n-butylamine. The peptide bonds are then reacted with an excess of copper(II) in a strong alkaline solution to form the so-called “biuret complex”. The simplicity of this method, which requires no separation or digestion, is adequate for full automation either with continuous flow or with discontinuous (automatic) analyzers. After a study of structure and absorption spectra of the different possible copper complexes, the main parameters are investigated, i.e. the concentration of the reagents (NaOH and Cu(EDTA)Na₂), the time and the temperature of the reaction.     

Spectres RMN haute resolution des homopolymeres et copolymeres de l'acrylate de glycidyle avec le chlorure de vinyle

The HR-NMR spectra of the glycidyl acrylate homopolymer and (glycidyl acrylate-vinyl chloride) copolymers are described. The assignment of the different resonance groups allows quantitative determination of the compositions of the copolymers.     

Isolement et identification de deux glucosyl-lutéolines mono-C-substituées et de la diglucosyl-6,8-lutéoline di-C-substituée dans les tiges feuillées de Passiflora incarnata L

Isolation and Identification of two Mono-C-glucosyl-luteolins and of the Di-C-substituted 6,8-Diglucosyl-luteolin from the Leavy Stalks of Passiflora incarnata L. The present work on Passiflora incarnata presents the isolation and the structural identification of C-glycosylluteolins, i.e. of orientin ( 1 ), homoorientin ( 2 ) and lucenin 2 ( 3 ). The latter compound is new for this plant.     

A propos de la structure de pyrimidines obtenues par condensation de l'acide cyanacétique et de monoalkylurées

Classically, the condensation of cyanoacetic acid and monoalkylurea gives 1-alkyl-6-amino-1,2,3,4-tetrahydropyrimidine-2,4-dione. However, this was verified only in two instances involving a long and delicate synthesis. The structure of the N′-cyanoacetyl-N-isobutylurea, an intermediate in the preparation of this type of pyrimidine, was confirmed by nmr. This method is capable of extension.     

Transpositions de doubles liaisons de p-menthènes et de p-menthadiènes catalysées par des bases

The displacements of double bonds by basic catalysts (N-lithioethylene diamine with an excess of ethylene diamine, potassium t-butylate in dimethylsulfoxide, benzyl-sodium in boiling xylene) are studied on p-menthenes and p-menthadienes. The isomerizations of p-menthadienes are accompanied by dehydrogenation. A representative mechanism of isomerization and dehydrogenation according to the catalyst is proposed for limonene.     

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.     

Isolement et identification de la C-galactosyl-8 apigénine dans les tiges feuillées de Carlina acanthifolia

Isolation and Identification of 8-C-Galactosylapigenin from Leaves of Carlina acanthifolia 8-C-galactosylapigenin was isolated from the leaves of Carlina acanthifolia (Compositae). This identification represents only the third report of a mono C-galactosylapigenin in plants and the first report in the Compositae.     

Etude des systèmes binaires formées par le chlorure de cyanogène et par les tétrachlorures de carbone,de silicium,de germanium et d'étain

Study of binary systems formed by cyanogen chloride and the tetrachlorides of carbon, silicon, germanium and tin. The diagrams of binary mixtures of cyanogene chloride with the tetrachlorides of carbon, silicon, germanium and tin were studied. Only SnCl₄ gives an addition compound: SnCl₄ · 2ClCN. The existence of the complex was confirmed by X-ray diffraction and vapour pressure measurements. This complex gives SnCl₄ · 2NOCl on treatment with nitrosyl chloride.     

Structure moléculaire et propriétés moléculaires de quatre isomères de formule C8H10N4

The molecular structures of the three Meyer isomers [3-methyl-3-(5′-amino-3′-methyl-l-pyrazolyl)acrylonitrile; acetylacetonitrile azine; 2,5-dimethyl-7-aminopyrazolo[1,5-a]pyrimidine] have been compared with that of the fourth isomer, 2,7-dimethyl-5-amino-pyrazolo[1,5-a]pyrimidine. The CNDO/2 and CNDO/S calculations utilizing these geometries have been accomplished. These include electronic transitions, dipole moments, ionisation potentials, charge densities, bond ordres and total energies. The calculated values have been compared to some experimental data. Uv spectra, ¹³C chemical shifts, ¹H-¹H coupling constants and relative stability of the four isomers are included.     

Étude structurale et vibrationnelle de solides moléculaires paramètres cristallins''et spectre d''absorption infrarouge en lumiére polarisée de

X-ray studies indicate that indanone-1 crystals belong to a monoclinic system, space group P2₁/c (C⁵_2h), with the following parameters: a = 7.90±0.01 Å; b = 12.38±0.01 Å; c = 7.39±0.01 Å; β = 99°±30' and Z = 4. A vibrational assignment of fundamental bands observed in the polarized infrared spectrum between 4000 cm⁻¹ and 250 cm⁻¹ is proposed. The band fine structure analysis at 77 °K shows a doublet structure, which agrees with X-ray data.     

Méthode d''analyse par chromatographie liquide haute performance des formultions à base de mélanges d''acides phénoxycarboxyliques, de dicamba, d''ioxynil et de bromoxynil

High-performance liquid chromatography analysis of formulations of phenoxycarboxylic acids, dicamba, ioxynil and bromoxynil mixtures

Eighteen mixed formulations of phenoxycarboxylic acids and other herbicides such as dicamba, ioxynil and bromoxynil have been analyzed by high-performance liquid chromatography using a r-μm Nucleosil 50 column.

The concentration of acetic acid in the eluent hexane-acetic acid depends on the formulation to be analyzed and on the analysis time. The formulations are extracted with a chloroform-diethyl ether mixture, and 20 μ1 of the extract are injected onto the coloumn. The compounds are detected at 285 nm.

The method is simple, rapid and the formulations are specificially analyzed without derivatization.     

Synthèse et caractérisation de fluorbritholites strontiques dopées au néodyme

Strontium fluorbritholites with the general formula Sr_10-xNd_x(PO₄)_6-x(SiO₄)_xF₂ (0 ≤ x ≤ 6), were prepared by solid state reaction at temperatures between 1200 and 1400 °C. The XRD analysis showed that a pure apatitic phase was formed only for x ≤ 2.5. Above this value, there was formation of secondary phases. The variation of the lattice parameters as a function of x indicated that the formed solid solution was discontinuous on both sides of x = 3. The analysis by Raman and IR spectroscopies confirmed the incorporation of SiO₄ groups within the apatite lattice, and showed that this incorporation induced in the structure a disorder that increased with increasing content of Nd³⁺ and SiO₄⁴⁻. Optical absorption measurements showed a wide variation in the local environment of Nd³⁺ ions, corresponding to the existence of new spectroscopic sites, evidenced by a luminescence study.     

Synthèse et réactivité des bromhydrines dérivées de la chromone

Bromohydroxylated derivatives of chromone are obtained by addition of N-bromosuccinimide in dimethylsulfoxide. The configuration and conformation of these compounds are confirmed by NMR spectroscopy. Alkaline alcoholates react with these bromohydrins to give a ring contraction into 2-formyl-3-benzofuranone.