Stabilité dans le méthanol et propriétés thermodynamiques de transfert des cryptates de certains cations de transition et de métaux lourds

Stability in Methanol and Thermodynamic Transfer Properties of the Cryptates of some Transition Cations and Heavy Metals The nature and stability of the macrocyclic and macrobicyclic complexes of Ag⁺, Cd²⁺, and Pb²⁺ (Mⁿ⁺) with 21, 22, 211, 221 and 222 in anhydrous methanol 0.05M in Et₄N⁺ClO^?₄, at 25° (see Scheme) have been determined by potentiometry and spectrophotometry. Binuclear complexes M₂L²ⁿ⁺ have been observed in all cases, besides the mononuclear MLⁿ⁺ complexes. The macrobicyclic 1:1 complexes MLⁿ⁺ exhibit an important ‘cryptate effect’ with Mⁿ⁺=Ag⁺, Pb²⁺ and Cd²⁺, but not with Cu²⁺ and Zn²⁺; their stability is in all cases maximum with 221. The applicability to our results of the recent extrathermodynamic hypothesis involving MLⁿ⁺ cryptates is examined.     

‘Non-Koopmans’ States in Stilbene Cations and a Remarkable Example to the «SDT-Equation»: Indeno [2,1-a]indene

The radical cations of indeno [2, 1-a]indene ( 1 ), stilbene ( 2 ) and 3, 5, 3', 5'-tetramethylstilbene ( 3 ) were prepared by γ-irradiation of the neutral precursors in an electron-scavenging matrix at 77 K . Their electronic spectra were recorded and compared to the photoelectron spectra ( PE .) of the neutral precursors. The results show that either the fourth or the fifth excited doublet state of the cations is of «Non-Koopmans» type, with specific doublet energy (D) D (²B_g)=2.74 eV ( 1 ⁺), =2.59 eV ( 2 ⁺), =2.49 eV ( 3 ⁺). Remarkably, 1 ⁺ possesses two electronic states in the 2.7-2.8 eV energy range: ²A_u («Koopmans»-type) and ²B_g («Non -Koopmans»-type). The «SDT»-equation \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm D} = \sqrt {{\rm S} \cdot {\rm T}} $\end{document} approximately connecting excited singlet (S) and triplet (T) states of a neutral alternant system with the excited doublet (D) states of its radical cation - provided e-promotion occurs For all three excited states between the same (paired) orbitals-is satisfyingly exemplified by 1 : S¹ = 3.92 eV and T¹= 2.06 eV for 1 , D^{4 or 5}=2.74 eV for 1 ⁺.     

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.     

Propriétés électriques du trioxyde de tungstène a proximité de sa composition stoechiométrique. Influence des conditions thermodynamiques de préparation et phénomènes de trempe

The experimental study of variations in electrical conductivity of WO_3−x vs oxygen partial pressure and temperature shows evidence of interstitial W⁶_i· as being the major defect. Under certain conditions, point defects can order themselves in extended defects. The behavior of electrical conductivity can be interpreted in terms of thermodynamic equilibrium between point defects and extended defects, the latter leading to structural modifications beyond a certain departure from stoichiometry. Moreover, WO_3−x shows evidence of quenching phenomena allowing it to keep electrical features characteristic of high temperatures down to room temperature. These properties may explain discrepancies between previous data.     

Die Komplexe der Hexamine «penten» und «ptetraen» Thermodynamik ihrer Bildung in wässeriger Lösung

The two hexamines (H₂N? CH₂? CH_{2? )2}N? (CH_2)n? N(? CH₂? CH₂? NH₂₎₂, «penten» (n = 2) and «ptetraen» (n=3) have been investigated as chelating agents for COIII (preparative Study) and some of the divalent metal ions (potentiometric and calorimetric studies). Both amines function as sexadentate ligands for Co^III, Co^II and Ni^II, but one of the terminal aminogroups is much easier detached from the metal in case of M (penten)^v+ than in case of M(ptetraen)^v+, thus revealing more strain in the fivemembered chelate rings of the girdle plane of the «penten» complexes. On the other hand, the sixmembered chelate ring in M(ptetraen)^v+ is more strained than the five-membered ring comprising the tertiary nitrogen atoms of M(penten)^v+ Cu^II and Zn^II coordinate with both ligands only 5 of the 6 basic nitrogen atoms present. Both hexaamines function as sexadentates again with Mn^II, but the metal is coordinated with a molecule of water in addition to the 6 nitrogen atoms in the «penten» complex in contrast to the «ptetraen» complex. The thermodynamic functions for the protonation of the hexamines and for the addition of metal ions in aqueous solution are understood in almost every detail. The dielectric shielding of the charges of the reactants exerted by the solvent has to be taken into account; it is reduced by electrostriction as well as by an increase in temperature. It is shown that the approach of charges of equal sign often is an exothermic process.     

Applications synthétiques de la cyclisation d'alcools tertiaires γ-éthyléniques en α-bromotétrahydrofurannes sous l'action du N-bromosuccinimide. I. Synthèse facile de la triméthyl-2,2,5-cycloheptène-4-one ou karahanaénone à partir du linalol

The ionic reaction of linalool and N-bromosuccinimide in CCl₄ at room temperature afforded 2-methyl-2-vinyl-5-(1-bromo-1-methyl-ethyl)-tetrahydrofuran (I). On treatment with refluxing collidine this compound yielded the intermediate allyl vinyl ether III, which immediatealy rearranged to 2,2, 5-trimethylcyclohept-4-en-one (V) or «karahanaenone» through a [3,3]-sigmatropic process. Karahanaenone, a constituent of hop oil, was thus synthesized for the first time (overall yield 62% from linalool). The mechanisms of these reactions are discussed.     

Etude de composés d'addition d'acides de Lewis,XXXIV [1] Composés d'addition de benzoquinone-1, 4 avec TiCl4

The adduct 1,4-benzoquine · TiCl₄ has been prepared in CH₂Cl₂ solution at about ?60°. Its IR. spectrum has been recorded at the same temperature. The experimental study of the vibrational frequencies has been completed by the calculation of the fundamental vibrations in the molecular plane, using Wilson's FG method, with slightly simplified models of 1,4-benzoquinone · TiCl₄ (13 masses) and 1,4-benzoquinone · 2 TiCl₄ (14 masses); analysis by use of internal and symmetry coordinates. An assignment of most of the observed bands is proposed and the conclusion is reached that the complex, when solid, is (1,4-benzoquinone · TiCl₄)_n. The force constants F(C? O) are 9,85 · 10⁵ dyne/cm for the quinone and 8,8 · 10⁵ dyne/cm for the disturbed carbonyl bond of the polymerized complex in the model proposed. At ordinary temperature in benzene solution of the components the adduct 1,4-benzoquinone. TiCl₄ · benzene precipitated; with the help of the models, the fundamental vibrations of its IR. spectrum have been assigned.     

Etudes sur les composés organométalliques V [1]. Action de la pyridine sur les organomagnésiens

By the action of pyridine on various Grignard reagents at room temperature, new diorganomagnesium complexes R₂Mg · 2pyridine (R=Ph, n-Bu, t-Bu and Et) were prepared and analyzed. Anomalous results were obtained with methyl- or benzylmagnesium reagents.     

Diénamines hétérocycliques. III. Réexamen de la réaction de la base de Fischer avec le tétracyanoéthylène

Heterocyclic dienamines III. A re-examination of the reaction of Fischer's base on tetracyanoethylene Depending on the order of addition, Fischer's base 5 (1,3,3-trimethyl-2-methylidene-indoline) reacts 1:1 with tetracyanoethylene to give either the tricyanovinylation product 6 or the spiro compound 7 . A skeletal rearrangement of a zwitterionic intermediate can explain the formation of the spiro compound. The latter undergoes a thermal isomerization yielding by ring expansion the tetrahydroquinoléine 8 . On reaction with LiAlH₄ or CH₃ONa 7 and 8 lead both to triazatetracycles. All structures are assigned on the basis of spectral data.     

Zur thermodynamisch-phänomenologischen Beschreibung der Färbevorgänge I. Diskontinuierliches Modellsystem

The essential characteristics of a simple, discontinuous model system for mass transfer between two phases are discussed. It is shown that for dyeing processes that conform to this model it is possible, with the aid of the methods of non-equilibrium thermodynamics, to give an unambiguous definition of the concepts «rate of dyeing» and «affinity of dyeing», at any stage of dyeing. It is clear from the derived phenomenological equations that dyeing systems rarely reach a true equilibrium state (i.e. a stationary state of zero order), but that in general an osmotic or a DONNAN equilibrium is attained.     

Recherches sur la formation et la transformation des esters LXXIX [1]. Sur la réaction de l′isothiocyanate d′o-méthoxycarbonyl-phényle avec divers acides et l′acide sérinephosphorique

Amino acids devoid of «leaving groups» on their β carbon atom (neither ? OH: serine, nor ? SH: cysteine) react with o-methoxycarbonyl-phenyl isothiocyanate (I) in the presence of one equivalent of NaOH, in water-dioxane or in ethanol, to yield the corresponding hydroquinazolinone derivatives II which were isolated as free acids. When treated with CH₃COOH + conc. HCl the hydroquinazolinone resulting from the reaction of L -serine with I undergoes a nucleophilic attack of the carbon bearing the leaving group ? OH by a lone pair of electrons of S; this attack produces the formation of an additional thiazolidine ring, yielding the thiazoloquinazolinone derivative (?)-III. In an analogous reaction DL -serine phosphoric acid treated with I at pH 8–9 yields the corresponding substituted hydroquinazolinone which, boiled in 1N hydrochloric acid, undergoes ring closure to (±)-III by the same mechanism as the serine derivative (leaving group: ? OPO₃H₂). L -Cysteine reacted with 2 equiv. of I and then treated with CH₃COOH + conc. HCl gives two products: (?)-III produced by the same mechanism as for serine (leaving group: ? SH), and the quinazolinone derivative IV where the ? SH group is also thiocarbamoylated.     

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.     

Effets Isotopiques dans la Fragmentation par Impact Électronique de Méthanols Deutériés

The mass spectra of the CH₃OH, CH₂DOH, CD₃OH, CH₃OD and CD₃OD methanols have been recorded at nominal electron energies ranging from 11 to 35 eV. Curves are given for the variation of the isotope effects related to the molecular ion stability and bond cleavage probabilities as a function of the electron energy, and are compared with a priori calculations. A simple distribution function and a value for the number of oscillators equal to half the theoretical figure give fairly satisfactory agreement, except as concerns the molecular ion stability. The form of the curves for the latter could be explained by the existence of an electronic state of the molecular ion other than the ground state.     

Spektroskopische Eigenschaften alkylsubstituierter Diazulyle (Die photochemische Darstellung des 3,3′ und des 2,2′ -Di-guaj-azulyls)

Irradiation with light of 366 nm wave-length of guay-azulene-2-sulfonic acid (IV) or of guay-azulene-3-sulfonic acid (I) dissolved in concentrated sulfuric acid yields 2,2′-di-guayazulyl (VI) or 3,3′-di-guay-azulyl (III) respectively. The nmr and electronic spectra of III and VI and of their conjugate acids are recorded. The essential features of the electronic spectra of III and VI can be understood in terms of a model based on SIMPSON'S «independent system approach».     

Nouvelle voie de synthèse des dérivés de l'ellipticine et analogues alcaloïdes à activité antitumorale

A new snythesis of 6H-pyrido[4,3-b]carbazoles is described starting from substituted cyclohexanones involving the combination of Borsche's carbazole preparation and Cranwell and Saxton's ellipticine synthesis where the starting materials are easily available. The dehydrogenation step is accomplished at an early stage. In some cases (11-desmethyl ellipticines derivatives), 7H-pyrido[3,4-c]carbazoles were also obtained.     

Propriétés themodynamiques des mélanges binaires. Chaleurs de mélange des n-alcanes ainsi que de leurs isomères

The following heats of mixing have been measured: the five isomers of hexane with n-dodecane at 10°, 20° and 30°C, and with n-hexadecane at 20°C, as well as the systems dodecane-hexene-1 at 20°C, and dodecane-methyl-2-pentene-1 at 10° 20° and 30°C.     

Star‐shaped poly(L‐lactide)s with variable numbers of hydroxyl groups at polyester arms chain‐ends and directly attached to the star‐shaped core—Controlled synthesis and characterization

Star‐shaped poly(L ‐lactide)s (PLAs) bearing variable numbers of secondary hydroxyl groups at linear arms chain‐ends and primary hydroxyl groups directly attached to dipentaerithritol core (DPE) ((HO)_6?xDPE(PLA‐OH)_x, where x = 1–6) were prepared and then analyzed by means of size exclusion chromatography (SEC), ¹H NMR spectroscopy, MALDI‐TOF mass spectrometry, and eventually by Liquid Chromatography at Critical Conditions (LC‐CC). First, starting from DPE(OH)₆ a series of polyols with various number of hydroxyl groups has been obtained ((BnO)_6?xDPE(OH)_x, where Bn denotes benzyl moiety and x = 1–6). The living ring‐opening polymerization of L ‐lactide (LA) with (BnO)_6?xDPE(OH)_x/tin(II) octoate mixtures as initiating and catalytic system led to star‐shaped (BnO)_6?xDPE(PLA‐OH)_x polymers with molar masses (M_n) controlled by LA and DPE concentrations ratio in the feed. Finally, deprotection (via hydrogenation) gave a series of (HO)_6?xDPE(PLA‐OH)_x PLA's. SEC (with Multiangle Laser Light Scattering Detector (MALLS)), NMR, and MALDI‐TOF analyses confirmed the assumed structures and M_n's of the prepared (BnO)_6?xDPE(PLA‐OH)_x and (HO)_6?xDPE(PLA‐OH)_x PLA's. LC‐CC measurements revealed that for (BnO)_6?xDPE (PLA‐OH)_x series the elution volumes increase monotonically with the increasing number of –PLA‐OH arms in one macromolecule and are independent on the given PLA molar mass because of the critical conditions. Contrary to the polymers having the protected core hydroxyl groups, the elution volume for (HO)_6?xDPE(PLA‐OH)_x series decreases with the increasing number of ‐PLA‐OH arms reaching a minimum value for 4‐arm PLA and then slightly increases for 5‐ and 6‐arm PLA. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6116–6133, 2005     

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.     

Réactions d'élimination présentées par des acides polyhydroxyadipiques

The tetrahydroxyadipic acids and one trihydroxyadipic acid have been methylated, using methyl iodide and silver oxide in the presence of dimethylformamide. In addition to Δ²-di- or tri-methoxyadipic esters and the products expected for a double E2 elimination, cis-trans α, α'-dimethoxymuconic ester was frequently the principal product. The proposed theoretical interpretations involve as intermediates either a silver complex or a lactonic compound. A few preferential conformations, based on NMR. data, are proposed.     

Sur quelques Nouvelles Phases Oxyfluorées de Structure “Bronzes Oxygénés de Tungstène Quadratiques”

On Some New Oxide Fluoride Phases of Tetragonal Tungsten Bronze Structure Six new oxide fluorides of tetragonal tungsten bronze type structure have been obtained by partial substitution of oxygen by fluorine in the ABCNb₅O₁₅ compounds (A = Ca, Sr, Ba; B = Ca, Sr, Ba; C = Na, K): CaK₂Nb₅O₁₄F, SrK₂Nb₅O₁₄F, SrKNaNb₅O₁₄F, BaK₂Nb₅O₁₄F, BaKNaNb₅O₁₄F and BaNa₂Nb₅O₁₄F. An investigation on Sr_2?xK_1+xNb₅O_15?xF_x and Ba_2?xNa_1+xNb₅O_15?xF_x solid solutions characterizes ferroelectric behaviour. Replacement of oxygen by fluorine decreases the Curie temperature, but for a small oxygenfluorine substitution rate an increase of the dielectric constant is observed.