BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-X. SYNTHESES AND ANALYSES OF SULFONATED PHTHALOCYANINES

Abstract— Synthetic methods to obtain selectively sulfonated metallo phthalocyanines are compared. Both condensation and direct sulfonation procedures lead to mixtures of mono- to tetrasulfonated products which are resolved by reverse phase liquid chromatography in buffered aqueous-methanol. The proportion of sulfonated derivatives is examined as a function of the starting reagents in the case of the condensation method, and as a function of the temperature and reaction time in the case of the direct sulfonation procedure. The number of sulfonate groups per phthalocyanine molecule is determined by oxidative degradation of the phthalocyanine ring followed by quantitative chromatographic analysis of the sulfophthalamide and phthalamide fragments.     

Enzymatic synthesis of neopentylpolyol esters in organic media

Utilization of lipases for synthesis of esters of hydrophilic polyols has been investigated. The choice of a suitable solvent is crucial in this type of reaction. An interesting case is fatty acid esters from neopentylpolyols, such as trimethylolpropane, which are of great interest as high temperature lubricants. Enzymatic synthesis of trimethylolpropane tricaprylate was studied as an alternative to chemical manufacturing. Triester production occurred only if the water produced by esterification was continuously removed from the medium. In these condition, kinetics of appearance and transformation of mono-, di- and triesters were determined in order to define optimal conditions.     

Substituent effects in mass spectrometry—II. The effect of substituents on the dissociation of para and meta disubstituted benzenes

The effect of substituents on the activation energy for primary dissociation processes in the molecular ions of mono- and para and meta di-substituted benzenes has been examined. Where the daughter ion retains the substituent group, variation of the energy of activation derives from a combination of the effects of substituents on the ionisation potential of the molecular ion and the appearance potential of the daughter ion. An equation relating the energy of activation for the fragmentation of the molecular ion of a mono-substituted benzene to that of related para and meta di-substituted benzenes is presented.     

A novel synthetic route to 2-alkylpropane-1,3-sultones and its application to the synthesis of 2-alkyl derivatives of tramiprosate

A practical synthetic route to various 2-alkylpropane-1,3-sultones, the key intermediates for the preparation of 2-substituted homotaurines as analogs of tramiprosate, was developed.     

Dendrophanes: Water-soluble dendritic receptors as models for buried recognition sites in globular proteins

Water-soluble dendritic cyclophanes (dendrophanes) of first ( 1 , 4 ), second ( 2 5 ), and third generation ( 3 6 ) with poly(ether amide) branching and 12, 36, and 108 terminal carboxylate groups, respectively, were prepared by divergent synthesis, and their molecular recognition properties in aqueous solutions were investigated. Dendrophanes 1 – 3 incorporate as the initiator core a tetraoxa[6.1.6.1]paracyclophane 7 with a suitably sized cavity for inclusion complexation of benzene or naphthalene derivatives. The initiator core in 4 – 6 is the [6.1.6.1]cyclo-phane 8 shaped by two naphthyl(phenyl) methane units with a cavity suitable for steroid incorporation. The syntheses of 1 – 6 involved sequential peptide coupling to monomer 9 , followed by ester hydrolysis (Schemes 1 and 4), Purification by gel-permeation chromatography (GPC; Fig. 3) and full spectral characterization were accomplished at the stage of the intermediate poly(methyl carboxylates) 10 – 12 and 23 – 25 , respectively. The third-generation 108-ester 25 was also independently prepared by a semi-convergent synthetic strategy, starting from 4 (Scheme 5). All dendrophanes with terminal ester groups were obtained in pure form according to the ¹³C-NMR spectral criterion (Figs, 1 and 5). The MALDI-TOF mass spectra of the third-generation derivative 25 (mol. wt. 19328 D) displayed the molecular ion as base peak, accompanied by a series of ions [M – n(1041 ± 7)]⁺, tentatively assigned as characteristic fragment ions of the poly(ether amide) cascade. A similar fragmentation pattern was also observed in the spectra of other higher-generation poly(ether amide) dendrimers. Attempts to prepare monodisperse fourth-generation dendrophanes by divergent synthesis failed. ¹H-NMR and fluorescence binding titrations in basic aqueous buffer solutions showed that dendrophanes 1 – 3 complexed benzene and naphthalene derivatives, whereas 4 – 6 bound the steroid testosterone. Complexation occurred exclusively at the cavity-binding site of the central cyclophane core rather than in fluctuating voids in the dendritic branches, and the association strength was similar to that of the complexes formed by the initiator cores 7 and 8 , respectively (Tables 1 and 3). Fluorescence titrations with 6-(p-toluidino)naphthalene-2-sulfonate as fluorescent probe in aqueous buffer showed that the micropolarity at the cyclophane core in dendrophanes 1 - 3 becomes increasingly reduced with increasing size and density of the dendritic superstructure; the polarity at the core of the third-generation compound 3 is similar to that of EtOH (Table 2). Host-guest exchange kinetics were remarkably fast and, except for receptor 3 , the stabilities of all dendrophane complexes could be evaluated by ¹H-NMR titrations. The rapid complexation-decomplexation kinetics are explained by the specific attachment of the dendritic wedges to large, nanometer-sized cyclophane initiator cores, which generates apertures in the surrounding dendritic superstructure.     

Kinetic applications of thermal analysis

A study was undertaken to compare two computational methods of estimating kinetic parameters from thermoanalytical experiments. Examples illustrating the relationship between reaction complexity and validity of isothermalvs. non-isothermal kinetic analyses will be presented. Thermal decomposition of several compounds was studied both by isothermal and dynamic thermogravimetry (TG). For the isothermal runs, reaction order and activation energy were estimated using established methods. For the dynamic runs, the statistical method of nonlinear least squares was used to estimate all three kinetic parameters of the nth order decomposition reaction and their individual 95% confidence intervals. Both methods assumed Arrhenius temperature dependence.

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Zusammenfassung Es wurde eine Untersuchung zum Vergleich von zwei Methoden zur Berechnung von kinetischen Parametern aus Ergebnissen thermoanalytischer Experimente unternommen. Beispiele werden angegeben, die die Beziehung zwischen isothermer und nichtisothermer kinetischer Analyse in Bezug auf Komplexizität der Reaktion und Gültigkeit illustrieren. Die thermische Zersetzung verschiedener Verbindungen wurde mittels isothermer und dynamischer Thermogravimetrie (TG) untersucht. Aus den isothermen Versuchsergebnissen wurden die Reaktionsordnung und Aktivierungsenergie nach den üblichen Methoden bestimmt. Aus den dynamischen Versuchsdaten wurden alle drei kinetischen Parameter der Reaktion n-ter Ordnung und deren individuelle 95%-Konfidenzintervalle nach der Methode der kleinsten Fehlerquadrate ermittelt. Beide Methoden setzen eine Temperaturabhängigkeit entsprechend der Arrhenius-Gleichung voraus.

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Presented at the 13th North American Thermal Analysis Society Conference, Philadelphia, PA 23–26 September 1984.     

Synthesis of trans-(3S)-amino-(4R)-alkyl- and -(4S)-aryl-piperidines via ring-closing metathesis reaction

[reaction: see text] trans-(3S)-Amino piperidines bearing various alkyl and aryl substituents at the C-4 position were synthesized via a ring-closing metathesis reaction. The absolute stereochemistry was controlled using a protected D-serine as a starting material. Stereoselective hydrogenation of allylamines provided trans-(3S)-amino-(4R)-alkyl- and -(4S)-aryl-piperidines. This procedure presents the first method for the asymmetric synthesis of 4-substituted 3-amino piperidines.     

Cascade polycyclization: exploration of a convergent route to access various tricyclic and tetracyclic products related to sterols

The expedient synthesis of tricyclic and tetracyclic compounds via a cascade polycyclization methodology is described. Nazarov substrates (II) containing two Michael acceptors and a cyclohexenone ester (I) underwent cycloaddition followed by intramolecular 1,4-addition to furnish, in a highly stereoselective manner, tricyclic and tetracyclic products (III). Such compounds are interesting intermediates for the synthesis of polycyclic natural and unnatural products.     

Two confined phases of argon adsorbed inside open single walled carbon nanotubes

Isothermal adsorption of Ar on single walled carbon nanotubes (SWNTs) has been studied at 77 and 87 K. The SWNTs have been grown by laser vaporization of a graphite pellet containing 0.6% (atomic) Ni/Co catalyst. The nanotubes have been prepared for argon adsorption measurements by prolonged outgassing of as-grown material in a vacuum at room temperature (295 K), at elevated temperatures of up to 475 K, and by oxidization for 2 h in dry air at 470 K. Formation of two condensed phases of Ar in the interior of SWNTs has been observed at 77 K. The low-density phase is formed at 155(5) microTorr, while the high-density phase, at 120(5) microTorr. At 87 K, only a single phase has been observed at 185(5) microTorr. Condensation at both 77 and 87 K appears to be the first-order phase transition. Onset of the quasi-one-dimensional linear (one-channel) phase and the quasi-two-dimensional monolayer (six-channel) phase formation on the external surface of bundles has been observed at 77 K near 0.0017 and 0.8 Torr, respectively, and at 87 K near 0.018 and 5 Torr, respectively. Isosteric heats of adsorption for the one-channel phase, the first external layer, and the second external layer have been determined to be equal to 137, 107, and 70 meV, respectively.