Analyse conformationnelle théorique des molécules de benzylidène-aniline,stilbène et azobenzène: Partie I. Résultats des méthodes INDO et MNDO; étude critique de leur application aux molécules conjuguées

A conformational analysis of the benzylidene-aniline, stilbene and azobenzene isoelectronic molecules has been carried out using the INDO and MNDO methods. The potential energy curves obtained with different geometric parameters are compared: the experimental values determined in the gas phase are only partly accounted for with the two methods. In order to understand these failures, the different terms contributing to the energy calculation are discussed (π—π and n—π conjugations, steric interactions) for the three molecules. It appears that each method is more sensitive to one term: the n—π conjugation is favoured in the INDO method, while the steric interaction is favoured in MNDO.     

Etude théorique et possibilités d'application de la méthode de «variations continues» [1] aux complexes très dissociés

A theoretical study of the possibilities of applicability to very unstable complexes of the «continuous variation» principle shows that the general equation of a theoretical Job's curve can be reduced, for limiting values of x and 1 ? x (x being the ligand's mole fraction), to expressions permitting the determination of the number «m» of the central groupes, the number «n» of the ligands, and the stability constants of highly dissociated complexes. Theoretical and practical limitations are discussed.     

Etude conformationnelle dans l'approximation CNDO/BW: barrière de rotation interne de petites molécules organiques

The potential functions for internal rotation of several representative small organic molecules are calculated by the CNDO/BW method. For ethane, methanol, propylene, methyl-cyclopropane and ethylene the most stable conformation is predicted correctly; although too small a value is calculated for the height of the rotational barrier, with the exception of ethylene for which the calculated value is very close to the experimental one. For glyoxal, butadiene and hydrazine the number of minima in the energy profiles or the or the associated values of the torsional angle are predicted incorrrectly (for butadiene, see however the note added to the proofs).     

Théorie quantique des phénomènes de biréfringence electrique et magnétique des molécules

A general formalism is set up to apply the variation-perturbation method to the quantum theory of non-linear optical effects, in particular to the electric and magnetic birefringence (Kerr and Cotton-Mouton effects). The quantities describing these effects are obtained from the wave function Ψ of the ground state of the unperturbed molecule and the different vectors and tensors which are determined by a variation method. With this method an approximate computation of the Kerr and Cotton-Mouton constants of some simple molecules has been made.     

Extension de la méthode du «logarithme limite» [1] pour la détermination de la composition et de la constante de stabilité des complexes

A study of the conditions of applicability to weak complexes of the relation log x = v log V + log (β_v,cC^c) = f(logV), where V and C are variable and constant total concentrations of the constituants of the complexe, shows that for conditions other than C ? V, another function φ(log V) accounts better for the formation equilibrium of the complexe. From f(log V) and φ (log V) a relation t(log V) is derived whose simple analysis permits the determination of the composition and the stability constant of weak complexes. Applications are given to 1:1, 1:2, 2:2 composition.     

Analyse en spectroscopie infrarouge, de la structure des complexes BF3 du méthanol, des méthanols deutériés et de l'acide acétique Comparaison de la liaison hydrogène et de la liaison donneur-accepteur

A study of the infrared spectra led to the conclusion that the 2-1 complexes formed from two molecules of methyl alcohol or acetic acid and one molecule of BF₃ have an open structure. One methyl alcohol molecule is linked by hydrogen bonding to a second molecule which is attached to BF₃. The consequences of the addition of BF₃ to the OH (OD) vibrators are similar to those of the formation of a hydrogen bond: elevation of the wave number of the in-plane bending vibration and lowering of the wave number of the stretching vibration compared with the monomer.     

Analyse conformationnelle de derives carbonylés du furanne et du thiophène par utilisation de la position et de l'intensite des bandes infrarouges

The carbonyl bands of 2-formyl and 3-formyl-furans [¹⁸O] are determined and explained. The magnitude of the inductive and mesomeric effects in 2-acyl and 3-acyl-thiophenes and furans is discussed on the basis of a comparison of the frequencies and the intensities of the v(CO) and v(CC) bands. The conformational preference of some aroyl-furans and aroyl-formyl-furans and the rotation around the C(Ar)-C(O) bonds are related to these parameters.     

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.     

Sur l'acylation des méthylfluorènes VI. Formylation du méthyl-2-fluorène et du méthyl-3-fluorène selon Rieche

The formylation of 2-methylfluorene and of 3-methylfluorene according Rieche yields 2-methyl-7-fluorene-carbaldehyde and 3-methyl-2-fluorenecarbaldehyde respectively. The constitution of the obtained aldehydes is proved by their conversion into the known 2,7-dimethyl-fluorene and 2,7-dimethyl-9-fluorenone, respectively into the known 2,3-dimethylfluorene and 2,3-dimethyl-9-fluorenone.     

Nouvelle méthode de détermination des taux de réativité des copolymères par résonance magnétique nucléaire: Application aux poly(méthacrylate de méthyle–chlorure de vinylidène)

Constant-composition copolymers of methyl methacrylate and vinylidene chloride produced by radical copolymerization are studied by ¹H-NMR at 60 and 250 MHz. The different methods of the literature for the derivation of reactivity ratios from either the copolymer composition or the sequence average lengths, or even the diad distribution, are applied but lead to rather dispersed results. A new graphical method is proposed, based on the use of peculiar values of the triad distribution functions. It allows us to detect a penultimate effect for the vinylidene chloride-rich region. In the same range, a change in tacticity of the diads and triads on the methylmethacrylate sequences, as compared with homopolymers, is observed; it suggests that the anomaly is caused by the competition of the depropagation reaction.     

Synthèse partielle et propriétés oncostatiques des pseudo-tubulosines,analogues de l'émétine et de la tubulosine

Partial Synthesis and Oncostatic Properties of Pseudotubulosines, Analogues of Emetine and Tubulosine Pseudotubulosines, structural analogues of emetine and tubulosine, have been synthesized by either Pictet-Spengler or Bischler-Napieralski condensation from dihydrocorynantheal or corynantheidal. Spectral data, cytotoxic and oncostatic properties of these new alkaloids are described.     

Isolement de nouveaux complexes de zinc de dipyrrométhènes formés au cours de la synthèse de la méso-tétramésitylporphyrine par la réaction de Rothemund

Three new zinc bis(dipyrromethene) complexes have been isolated in the preparation of meso-tetramesitylporphyrin by the Rothemund zinc template based condensation process.     

Copolymerisation radicalaire du méthacrylate de méthyle et du chlorure de vinylidène avec ou sans dérive de composition

Two sets of methylmethacrylate-vinylidene chloride copolymers were prepared via radical copolymerization in dimethylformamide. The first set is carried out in batches. Gas-chromatographic analysis of samples allows a kinetic study from which the reactivity ratios r_M - 2.73 and r_C - 0.24 are derived. For the second set a new apparatus, briefly described, has been used. It permits to keep constant the composition of the monomer mixture, through addition of methyl methacrylate, monitored by a chromatographic analysis. The two sets of copolymers are analyzed using nuclear magnetic resonance (60 MHz) leading to the triad distribution, from which the reactivity ratios are derived. Owing to the composition drift, the method cannot be applied to the first set of copolymers; but in that case, it is possible to calculate the triad distribution, the knowledge of the reactivity ratios, and the calculation fits quite well the experimental results.     

Régio et périsélectivité de réactions de diels-alder et des cycloadditions dipolaires-1,3 avec une triazépine-1,2,4: Approche théorique

e.s The cycloaddition of 1,3-dipoles (mesitonitrile, C,N-dimethylnitrone) and various dienophiles (DMAD, maleic anhydride) to 1,2,4-triazepine 1 are peri and regiospecific. Nitrone excepted the preferred orientation of addition is predicted correctly by FMO/MNDO calculation.