Preparation de β-cetonitriles via l'acylation du cyanacetate de trimethylsilyle par les anhydrides mixtes.

β-ketonitriles R¹COCH₂CN and R¹COCH(R²)CN are respectively prepared from (CH₃)₃SiOCOCHLiCN or R²CHLiCN by acylation reaction with mixed anhydrides RCOOCO₂Et.     

Cinetique et mecanisme de la reaction de prototropie des composes propargyliques alleniques et propynyliques portant un heteroatome (colonne vb et vib)

A detailed kinetic study of the prototropic rearrangement of the system RMCH₂CCH?RMCHCCH₂?RMCCCH₃ where M = NR, O, Se is presented. using deuterated substrates the nature of the reactive intermediates and, in the case of M = S, the activation energy-reaction profile are established.     

Etude structurale de composes organosilicies par diffusion rayleigh depolarisee: VI. Effets electroniques dans les systemes Cz.dbnd;CSi,PhSi,SiCC, SiNSi Et Si3N

Depolarised Rayleigh scattering is sensitive to conjugated electronic effects. The proper effect of silicon bonded to an sp² carbon atom in Me₃SiPh and Me₃SiCHCHΣ (Σ = H, Me, t-Bu, SiMe₃) has been illustrated by comparison of the systems containing a C_sp²M bond with the corresponding systems containing a C_sp³M bond for M = C, Si. To be able to make this comparison it was necessary to study the additivity of the bond and group optical anisotropies in alkenes with Me, CMe₃, SiMe₃ groups by means of a more approximate model assuming axial symmetry for the CC bond but of more convenient and more general use than a more realistic model without axial symmetry. Contrary to the NSi (from monosilylamines), SiOC and SiOSi systems, silicon adjacent to an unsaturated system, causes an exaltation of the optical anisotropy which mainly results from increase of the longitudinal optical polarisability. This exaltation is consistent with electron delocalisation in an orbital obviously longer than the basic π orbital. Such an effect seems strengthened in (Me₃Si)₂NΣ if the donating ability of Σ increases, Σ = H, Me, t-Bu. For Me₃SiCHCHSiMe₃ and if the molecules Me₃SiNHΣ¹ (Σ¹ = Me, t-Bu), (Me₃Si)₂NH and (Me₃Si)₃N are compared, a compensation is observed between the effect of the new lengthening of the π orbital and the π electronic density fall by CSi or NSi bonds.     

Asymmetrically substituted ferrocene derivatives showing redox switching of optical properties

The electrochemical and spectroelectrochemical behaviors of three ferrocene derivatives, (1) (C₁₈H₃₇)₂NC₆H₄CHCHFcCH₂OH, (2) (C₁₈H₃₇)₂NC₆H₄CHCHFcCHO, (3) (C₁₈H₃₇)₂NC₆H₄CHCHFcCHC(CN)₂, were studied and analyzed on basis of frontier orbital interactions. It was shown that all the three derivatives show two oxidation steps. The first oxidized states of 1 and 2 are stable and show strong LMCT (ligand-to-metal charge transfer) bands. This suggests that they may serve as redox switching of optical properties. In contrast, the first oxidized state of 3 becomes unstable due to strong electron-withdrawing effect of the acceptor substitute.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

Extension de la reaction de Wittig: Condensation “d'ylures enolates” sur les cetones aliphatiques

The enolate ylide Ph₃P⁺C^?C(Ph)O^?Li₊ obtained by the reaction of HMPT-Li with the benzoylmethylenetriphenylphosphorane Ph₃PCHCOPh reacts with aliphatic ketones, in contrast to its precursor. This condensation makes it possible to prepare β,γ-unsaturated ketones, of type RCHC(R′)CH₂COPh, instead of the α,β isomer usually obtained in a Wittig reaction.     

Enzymes immobilisees—IV : Les vanacryls et leur emploi dans la preparation de nouveaux derives insolubles de la trypsine

Treatment of methacrylyl chloride with vanillin gave the corresponding ester 1 which was polymerized (or co-polymerized with allylic alcohol), to give various polyaldehydes, called vanacryls. These polymers were successfully used for immobilizing trypsin according to the probable scheme: PolCHO + H₂NEnz → PolCHNEnz.     

Réactions des céténes et du dicéténe avec les germyl- et silylphosphines

Ketenes add to germyl- and silylphosphines R₃MPEt₂ with opening of the carbonyl group and formation of phosphorylated alkenoxygermanes or -silanes

(R′H, Ph). These adducts are thermally stable and only the addition derivative of diphenylketene and Me₃SiPEt₂ exhibits metallotropic isomerization to a C-derivative after prolonged heating. Hydrolysis of these addition compounds is a new approach to the acylphosphines R₂CH-CO-PEt₂. Diketene also reacts with germyl- and silylphosphines with acyloxygen bond cleavage and formation of metallated and phosphorylated ketoenolates of the type

. These derivatives isomerize either partially (MSi) or completely (MGe) into R₃MOC(CH₃)CHCOPEt₂. Their hydrolysis constitutes a new method of synthesis of the phosphorylated β-diketone

. The ketoenolates from the addition reaction of the hydrosilylphosphine, Me₂Si(H)PEt₂, cyclize readily after partial isomerization by the intramolecular addition SiH to CO, to give phosphorylated siladioxane and siladioxene. The conformation of these heterocyclic compounds has been studied.     

Synthese de materiaux polymeres transparents. Partie I Synthese du trifluoroacrylate de trideuteromethyle

The acrylic ester F₂CCFCO₂CD₃ is prepared from a mixture of difluorotetrachloroethanes CFCI₂CFCI₂ and CF₂CICCI. The dehalogenation of these Freons, followed by the addition of CFCI₃ by means of AICI₃ leads to a mixture of chlorofluoropropanes. The hydrolysis with oleum gives the acid chlorides which are then esterified by CD₃OD. The dehalogenation of the mixture by the zinc stirred in oxalic acid enables isolation of the expected ester by distillation. This compound, the refractive index of which n²⁰_D=1.3667 does not show a major absorption in the near infra-red between 0.6 and 1.4 μm. Thus the corresponding polymer is likely to provide a good material for the core of optical fibers.     

Fluoration de telomeres polyhalogenes par le fluorure de potassium (2ème partie). Synthese d'olefines perfluorees de hauts poids moleculaires

Fluorination of chlorofluorinated telomers of general formula Cl(CFClCF₂)_nCCl₃ (n ? 7) was studied using potassium fluoride in dimethylsulfoxide as fluorinating agent. The reaction leads to a mixture of perfluorinated linear olefins having 15 to 30 carbon atoms : CF₃(CF₂)_pCFCF(CF₂)_mCF₃ (p + m = 2n?3).We perfected a method to determine molecular weights of the telomers by gel permeation chromatography (G.P.C.). The olefins obtained by fluorination are analyzed both by vapor phase chromatography (V.P.C.) and by ¹⁹F nuclear magnetic resonance (N.M.R.).     

Mise au point d'un appareillage de preparation et de manipulation de melanges anhydres HFNH3MF (M alcalin) — tension de vapeur totale au-dessus de solutions HFNH3 riches en HF

An apparatus for preparing and handling HFNH₃MF mixtures (M alkali metal) has been designed and constructed. The vacuum line made of plastic materials (PVF₂, PTFCE, PTFE) allows the purification of anhydrous hydrogen fluoride, preparation and analysis of HFNH₃ or HFNH₃MF mixtures and their handling for further study or destruction.Total vapour pressures above HFNH₃ binary mixtures rich in HF have been measured and are described as a function of ammonia concentration and temperature (?10 to +20°C).     

Spectroscopic studies of [M(CO)5M′(CO)3(1,4-diazabuta-1,3-diene)] (M,M' = Mn,Re) and their photolysis products

Photolysis of [M(CO)₅M′(CO)₃(dab)] (M, M′ = Mn, Re; dab = 1,4-diazabuta-1,3-diene, RNCHCHNR) in 2-Me-THF leads to both homolytic and heterolytic splitting of the metalmetal bond depending on the solution temperature. In a rigid medium such as a CH₄-matrix no breaking of the metalmetal bond is observed but instead formation of [M(CO)₃M′(CO)₃(dab)] in which compound the dab-ligand is σ,σ,π,π bridging between M and M′.     

Etude de la degradation thermique des oligomeres du polyacrylonitrile

To obtain more information on the reactions during the pyrolysis of polyacrylonitrile at 290° in air, we studied the thermal degradation of its trimers, tetramers and pentamers having the general formula: R  CH(CN)  CH₂  CH(CN)_n?1  R where R = H or CH₃ and n = 3,4,5. Study by gas chromatography of the volatile compounds produced during pyrolysis at 290° and 770° showed that the first step of the degradation is homolytic scission of the chain. There are then intra and intermolecular polymerisations of the nitrile groups and formation of a ladder polymer. This reaction is clearly exothermic only for pentamers. This increase of the reactivity with DP is borne out by a kinetic study by EPR of the pyrolysis in air at 290°, oxidation of the ladder polymer giving a paramagnetic solid. Its EPR characteristics (band width and number of spins per g) are very dependent of the DP and nature of the end-groups, H or CH₃, of the pyrolysed oligomer.     

Structure electronique de silacyclopentenes-2 et -3

Photoelectron spectroscopy is used to compare the electronic structures of 1,1′-dimethylsilacyclopent-3-ene, 1,1′-dimethylsilacyclopent-2-ene and several phenyl, vinyl and allyl derivatives. When a π orbital is on α position of the silicon atom, a hyperconjugation (α(SiC)π interaction) and a homoconjugation (p_πd_π interaction) are observed. The polarization induced by the P_πd_π interaction explains the differences of nucleophilic reactivity showed by the compounds studied. Also, the analysis of the shifts of first ionization potentials made it possible to propose a conformation for 1,1′-diallylsilacyclopent-3-ene.     

Utilisation de methodes de trempe ultra-rapide pour une nouvelle chimie du fluor

Quick quenching preparation from the melt has been extensively used for new fluoride preparations. Some examples are given for obtaining either non crystalline solids (PbF₂AlF₃; PbF₂ZnF₂; Sb₂O₃SbOF systems) or metastable crystalline fluorides (Li₂ZnF₄; SnF_2+x; Sb(O, F)_2+x). A new quenching method called ‘reactive splat-cooling’ well adapted to fluorides is described.     

The rotational barrier in dimethyl acetylene and related molecules

The rotational barriers in dimethyl acetylene (CH₃CCCH₃), diamino acetylene (H₂NCCNH₂), dihydroxy acetylene (HOCCOH), methyl trifluoro methyl acetylene (CF₃CCCH₃), silyl methyl acetylene (SiH₃CCH₃), propene, cis and trans 2-butene and ethane were studied by ab initio molecular orbital methods using various basis sets. The eclipsed structure for dimethyl acetylene and its CF₃ and SiH₃ analogs was found to be the most stable, as has been inferred from experimental work, and the barrier height for these compounds has been predicted. The barriers in the OH and NH₂ substituted acetylenes, propene, butene and ethane were studied in order to more clearly understand the important influences in determining the barrier mechanism; specifically, the delocalized molecular orbital and Pauling VB model have been compared.     

Zur reaktion von iminodithiocarbonaten mit carbonsäuren I: Synthese des modellpeptid-derivates Z(L)Ala(L/D)Phe(L)ValOMe

The tripeptide derivative Z(L)Ala(L/D)Phe(L)ValOMe was obtained in 40% yield by reacting (CH₃S)₂CN(L)CH[CH(CH₃)₂]COOCH₃ with the dipeptide derivative Z(L)Ala(L)PheOH and ZnCl₂ at 110°C. The product obtained by bulk condensation contained 9 %, the product obtained utilizing ethylene carbonate as solvent contained 10 % of the diastereomer Z(L)la(D)Phe(L)ValOMe. Separation of diastereomers was achieved by HPLC on a silicagel column.     

Telomerisation par catalyse redox—IV: Telomerisation du chlorotrifluoroethylene avec le tetrachlorure de carbone

Telomerization of chlorotrifluoroethylene by redox catalysis with carbon tetrachloride led to Cl₃C(CF₂CFCl)_nCl telomers. The structure of these compounds was determined by mass spectrometry, ¹⁹F NMR and by chemical transformation of the end-groups. Taxogen to telogen molar ratio variations and the use of different metal catalysts made it possible to direct the reaction to a given degree of polymerization. Finally, the transfer constants and the energetic coefficients were calculated by kinetic study of the reactions.     

Studies on novel unsymmetrical azomethines—III : Copper(II) complexes of unsymmetrical tetradentate azomethines

Copper(II) complexes of unsymmetrical bifunctional tetradentate azomethines having the general formulae, (OC₁₀H₆CH:NXN:C(R)C₆H₄O)Cu, (OC₁₀H₆CH:NXN:C(CH₃)CHC(CH₃)OCu, (OC₆H₄CH:NXN:C(CH₃)C₆H₄O)Cu, (OC₆H₄C(R);NXN:C(CH₃)CHC(CH₃)O)Cu (where R = H or CH₃, X = (CH₂)₃, (CH₂)₄, (CH₂)₆ or -oC₆H₄) have been synthesized by the reactions of preformed mixed imine complexes of the type, CuLL′ (where L and L′ are two different imines such as 2-hydroxy-1-naphthaldimine, salicylaldimine, o-hydroxyacetophenonimine or acetylacetonimine) with diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane or o-phenylenediamine. These complexes have been characterized by elemental analyses, TLC, conductance, magnetic measurements, IR and electronic spectra.     

Synthese regiospecifique et identification spectrale de nouveaux amino pyrazoles F-alkyl substitues

In this paper the regiospecific synthesis of new amino-3 (-5)pyrazoles substituted, by a long perfluoroalkyl chain (C₇F₁₅) in the 5 or 3 position is reported. These compounds were obtained by condensation of a hydrazine (substituted or not) with a 2-F-alkyl propynonitrile (R_FCCCN). This reaction gives only one isomer. Each isomer (amino-3 pyrazole or amino-5 pyrazole) was identified by ¹H N.M.R. and ¹⁹F.N.M.R.