Zirconium-catalyzed one-pot synthesis of ɛ-spirocyclopropyl-ɛ-caprolactones

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Anionic polymerization of ɛ-caprolactam in the presence of piperidine N-carboxamides

Piperidine N-carboxamides were shown to activate the anionic polymerization of ?-caprolactam. The activator structure affects properties of the resulting polycaproamide.     

Synthesis of ɛ-caprolactone with stable hydrogen peroxide adducts

Oxidation of cyclohexanone to ?-caprolactone with stable industrially manufactured hydrogen peroxide derivatives: adduct with urea (urea hydrogen peroxide), sodium perborate, sodium percarbonate (Persol), magnesium monoperphthalate (Dismozon) was studied. Oxidation with urea hydrogen peroxide is the most efficient in hexafluoroisopropanol in the case of preliminary removal of urea in the form of an oxalate. Oxidation with sodium perborate and percarbonate provides high yields in trifluoroacetic acid. The lowest cost process consists in interaction with sodium monoperphthalate (Persol and phthalic anhydride) in an aqueous medium.     

Catalysis of cure reaction of ɛ-caprolactam-blocked polyisocyanate with diol using non-tin catalysts

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Catalysis of cure reaction of ?-caprolactam-blocked polyisocyanate with 1,4-butane diol in the presence of DABCO - a tertiary amine, tin(II) 2-ethylhexanoate and non-tin organometallics like bismuth neodecanoate, calcium(II) 2-ethylhexanoate and zinc(II) 2-ethylhexanoate was investigated. The activity of these catalysts was studied by the determination of cure-time (gel-time) and analysis of absolute molecular weight of cured polymers. Cure-time results indicated that all the non-tin organometallics act as catalysts; they were more active than DABCO and except bismuth neodecanoate, other two non-tin compounds were also found to be equally active or more active than tin(II) 2-ethylhexanoate. Within the three organometallics studied, zinc (II) 2-ethylhexanoate showed highest catalytic activity, it reduced the cure-time more than 50% compared to the uncatalysed reaction. In the case of bismuth neodecanoate catalysed reaction, it was found that the viscosity was build-up to a certain limit and then decreased; this catalyst assisted chain degradation was confirmed by the analysis of molecular weight of polymers as a function of time. Catalytically active new species was formed when mixing the solution of DABCO to the solution of zinc (II) 2-ethylhexanoate and this formation was confirmed using FT-IR and UV-visible spectroscopy, but this species not showed synergism.     

Ring-opening polymerisation of ɛ-caprolactone catalysed by Brønsted acids

Two new Brønsted acids [2,2′-ethylidene-bis (4,6-di-tert-butylphenol)] phosphoric acid (EDBPPOOH) and (3,3′,5,5′-tetra-tert-butylbiphenyl-2,2′-diol) phosphoric acid (TBPO-POOH) were synthesised and fully characterised by ¹H NMR and ¹³C NMR spectra and mass spectra. The ringopening polymerisation (ROP) of ?-caprolactone (?-CL) catalysed by the two Brønsted acids proceeded at 110°C without a solvent or at ambient temperature in toluene. Experimental results indicated that the two Brønsted acids were efficient catalysts for the ROP of ?-CL with moderate number-average molar mass (Mn) and narrow polydispersity indices (PDI). The catalytic activity of TBPO-POOH is higher than EDBP-POOH in the ROP of ?-CL. After benzyl alcohol was added, it was able to accelerate the polymerisation process. The polymerisation can also occur with the addition of water with a monomer/catalyst/initiator mole ratio of 100: 1: 1. The living polymerisation was ascertained by the linear relationships of the Mn vs. monomer conversion, then it was further confirmed by a second-feed experiment of a double monomer producing double Mn. A kinetic study of the relationships between monomer concentration and time revealed a first-order dependence on monomer concentration in the polymerisation. End-group analysis of ¹H NMR spectra and electrospray-ionisation mass spectra suggests that the two Brønsted acids are capable of catalysing and initiating the ROP of ?-CL.     

ɛ-TaN as a Reference Material for the Determination of High Nitrogen Contents

Today it is possible to replace the costly Kjeldahl method by the commonly used Carrier Gas Hot Extraction (CGHE) method for the determination of nitrogen contents of up to 50wt%, because the accuracy of this method was improved up to a 0.2% relative standard deviation. The remaining problem is the availability of defined and stable standards for N analyses by Carrier Gas Hot Extraction. In this study, we compared different certified standards with -TaN, which is a so-called line compound with a defined nitrogen content.A nitrogen content of almost theoretical composition was found for -TaN using compact samples analysed by CGHE and combustion-GC (Dumas-GC) analysis while the nitrogen content decreased in powdered samples. -TaN is a well-suited and stable potential reference material especially if the gas analyser is capable of analysing and decomposing compact pieces of this material.     

Time-dependent mussel-inspired functionalization of poly(L-lactide-co-ɛ-caprolactone) substrates for tunable cell behaviors

Surface properties of biomaterials, such as hydrophobic/hydrophilic balance, chemical group distribution, and topography play important roles in regulation of many cellular behaviors. In this study, we present a bio-inspired coating of synthetic biodegradable poly(L-lactide-co-?-caprolactone) (PLCL) films by using polydopamine for tunable cell behaviors such as adhesion and proliferation. Polydopamine coating decreased the water contact angles of the PLCL film from 75° to 40°, while the amount of coated polydopamine increased from 0.6 μg/cm(2) to 177.9 μg/cm(2). During the process, dopamine could be directly polymerized on the surface of the PLCL film to form a thin layer or nanosized particles of self-aggregates, which resulted in increase of overall roughness in a time-dependent manner. Characterization of surface atomic composition revealed an increase in signals from nitrogen and the C-N bond, both suggesting homogeneous polydopamine coating with prolonged coating time. The mechanical properties were similar following reaction with polydopamine for a time shorter than 30 min, while alterations in elongation and Young's modulus were observed when the coating time exceeded 240 min. Cell adhesion and proliferation on the polydopamine-coated films were significantly greater than those on the non-coated films. Interestingly, these cell behaviors were significantly improved even under the minimal coating time (5 min). In summary, the bio-inspired coating is of use to generate modular surface of biomaterial based on synthetic poly(α-hydroxy ester)s for tunable cell behaviors with optimization of coating time within the range in which their mechanical properties are not compromised.     

Determination of Nɛ-homocysteinyl-lysine and γ-glutamylcysteine in plasma by liquid chromatography with UV-detection

Homocysteine (Hcy) is a sulfur-containing nonprotein amino acid, a metabolite of methionine. Mechanisms by which Hcy is involved in the pathogenesis of vascular diseases remain unclear. One of the potential mechanisms underlying harmful effects of Hcy is the protein N-homocysteinylation induced by Hcythiolactone. Proteolytic degradation of N-homocysteinylated protein yields N?-homocysteinyl-lysine, a novel and important component of Hcy metabolism. Here we describe new high-performance liquid chromatography assay for the determination of N?-homocysteinyl-lysine and γ-glutamylcysteine in plasma, based on a derivatization with 2-chloro-1-methyllepidinium tetrafluoroborate and UV detection. Baseline separation was achieved on an analytical column from Phenomenex (Kinetex C18, 100 × 4.6 mm, 2.6 μm) using gradient elution, with a mobile phase consisting 0.1 M trichloroacetic acid (pH 2.3) — acetonitrile. The quantification limits for N?-homocysteinyl-lysine and γ-glutamylcysteine in plasma were 0.1 and 0.2 μM, respectively. Other main endogenous thiols can also be measured during the same analytical run. The proposed method was applied for the analysis of 15 plasma samples for total form of N?-homocysteinyl-lysine and γ-glutamylcysteine.     

Synthesis and crystal structure of lanthanum(III) Iodomercurate(II) complexes with ɛ-Caprolactam

The X-ray diffraction study of the crystalline products of the reaction between potassium tetraiodomercurate(II), ?-caprolactam, and lanthanum(III) nitrate at a ratio of 3: 16: 2 in an aqueous solution has shown the presence of the following three new crystalline compounds: [LaCpl₈]₂[HgI₄]₃ (I), [LaCpl₈][HgI₄]I₃ (II), and [LaCpl₇(H₂O)]₂[HgI₄]₂[Hg₂I₆] (III), where Cpl is ?-caprolactam ?-C₆H₁₁NO. Compounds I and II crystallize in tetragonal crystal system, space groups P4₂/n and $I\bar 4$ , respectively. For compound I, a = 18.59320(10) Å, c = 19.5782(3) Å, V = 6738.32(12) ų, Z = 2, and ρ_calc = 2.067 g/cm³. For compound II, a = 13.2245(10) Å, c = 20.0310(3) Å, V = 3503.17(6) ų, Z = 2, ρ_calc = 2.022 g/cm³. The crystals of compound III are monoclinic (space group P _{2 1}/n, a = 20.1202(6) Å, b = 14.0569(4) Å, c = 46.3228(12) Å, β = 93.4770(10)°, V = 13077.3(6) ų, Z = 4, ρ_calc = 2.274 g/cm³). [La(Cpl)₈]₂[Hg₂I₆]₃ (IV), a new double ionic complex salt, has also been synthesized and studied by X-ray diffraction. The crystals of compound IV are triclinic (space group $P\bar 1$ , a = 12.5021(3) Å, b = 14.6436(3) Å, c = 21.4695(4) Å, α = 84.2300(10)°, β = 87.2230(10)°, γ = 74.9970(10)°, V = 3776.30(14) ų, Z = 1, ρ_calc = 2.452 g/cm³). All complexes have a dicrete ionic structure, and the nearest surrounding of a La atom is distorted square-prismatic or trigonal-dodecahedral. The crystal packing of cations is distorted face-centered cubic (I and II) or body-centered cubic (III and IV) with anions located in its cavities.     

Genetically directing ɛ-N, N-dimethyl-L-lysine in recombinant histones

A molecular understanding of the biological phenomena orchestrated by lysine N(?)-methylation is impeded by the challenge of producing site-specifically and quantitatively methylated histones. Here, we report a general method that combines genetic code expansion and chemoselective reactions, for the quantitative, site-specific installation of dimethyl-lysine in recombinant histones. We demonstrate the utility of our method by preparing H3K9me2 and show that this modified histone is specifically recognized by heterochromatin protein 1 beta. Extensions of the strategy reported here will allow a range of chemoselective reactions (which have been used for residue-selective, but not site-selective protein modification) to be leveraged for site-specific protein modification.     

Formation conditions of a magnetically ordered phase ɛ-Fe2O3. A FMR in situ study

The ferromagnetic resonance (FMR) method in situ is used to study the initial stages of the formation of ? iron oxide nanoparticles deposited on silica gel at temperatures up to 600°C. It is shown that at high-temperature treatment of starting samples obtained by impregnation with an iron(II) sulfate solution, supermagnetic ?-Fe₂O₃/SiO₂ nanoparticles form with a narrow size distribution. An analysis of the FMR data in comparison with the data of other methods enables the formulation of the formation conditions for systems of deposited ?-Fe₂O₃ nanoparticles without other polymorph impurities.     

Thermal analysis of rare-earth metal(III) hexa(isothiocyanato)chromate(III) complexes with ɛ-caprolactam

Thermal decomposition of the complexes [LnL₈][Cr(NCS)₆] (Ln = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺, Lu³⁺; L = ɛ-C₆H₁₁NO) in air and in inert atmosphere was studied by thermogravimetry, X-ray phase analysis, IR spectroscopy, and mass spectrometry. The compositions of gaseous and solid thermolysis products were established. A reversible thermochromic effect was found on heating to 200–210°C.     

Syntheses of biodegradable graft copolymers from sodium caseinate and poly ɛ-caprolactone or poly lactic acid. Applications to the compatibilization of sodium caseinate/polyester blends

Casein (and its sodium salt, sodium caseinate, SC) is an inexpensive natural milk protein that is used as a biodegradable biomaterial, especially to produce packaging films. However, to enhance some of its properties, it needs to be blended with other polymers, which should preferably be biodegradable such as poly lactic acid (PLA) and poly ε-caprolactone (PCL). New SC-g-PLA and SC-g-PCL graft copolymers have been prepared and unambiguously characterized, in particular by ¹H and DOSY NMR. The grafting degrees are high (between 24 and 35% by weight) and result in variations of properties, such as hydrophobicity and thermal properties. The microstructures of SC/PLA and SC/PCL blends were studied and compared, with and without the addition of the SC-g-PLA and SC-g-PCL copolymers to test the compatibilization capacity of these new biodegradable copolymers.     

Studies on the phase behavior and solubilization of the microemulsion formed by surfactant-like ionic liquids with ɛ–β-fish-like phase diagram

The phase behavior and the solubilization of the microemulsion systems surfactant-like ionic liquids 1-hexadecyl-3-methylimidazolium bromide (C₁₆mimBr), 1-tetradecyl-3-methylimidazolium bromide (C₁₄mimBr), or 1-dodecyl-3-methylimidazolium bromide (C₁₂mimBr)/alcohol/alkane/brine have been studied with ɛ–β-fish-like phase diagram method at 40 °C and an oil-to-water mass ratio of 1:1. From the ɛ–β-fish-like phase diagram, the physicochemical parameters, such as the mass fraction of alcohol in the hydrophile–lipophile-balanced interfacial layer (A ^S), and the solubilities of ionic liquid (S ^O) and alcohol (A ^O) in alkane phase, were calculated. The solubilization of the microemulsion system has been discussed based on the ɛ–β-fish-like phase diagram. The smaller the oil molecule, the longer the alcohol chain length, and the larger the NaCl concentration in water, the larger the solubilization of the microemulsion system. In this paper, the solubilization of the microemulsion stabilized by both C₁₂mimBr and sodium dodecyl sulfonate (sodium dodecyl sulfate) was also investigated with the ɛ–β-fish-like phase diagram. The unequimolar composite of anionic and cationic surfactants can avoid the sedimentation aroused by the strong electrostatic attraction, and an obvious synergism effect in solubilization was obtained.     

Activity coefficients of NaCl in aqueous mixtures with ɛ-increasing co-solvent: Formamide–water mixtures at 298.15 K

The electromotive force of the cell containing two ion-selective electrodes (ISE),

Na-ISE|NaCl(m), formamide (Y), H₂O(100 − Y)|Cl-ISE

Über den Mechanismus und die Kinetik der ɛ-Caprolactam-Polymerisation in Gegenwart von Wasser

Zusammenfassung Die Bildungskinetik des Poly--Caprolactams wird experimentell bei 220° in Gegenwart von 0,01, 0,02, 0,04 und 0,08 Mol Wasser und von 0,01 Mol-Aminocapronsäure pro Mol Gesamtlactam zu Reaktionsbeginn untersucht. Die Meßergebnisse werden in Tabellen und vergleichend in Abbildungen dargestellt und diskutiert.Bei Wasser als Reaktionskomponente sind die Laotamumsatz- und Polymerisationsgrad-Zeit-Funktionen Wendepunktsfunktionen, in denen eine Induktionsperiode der Reaktion zum Ausdruck kommt; bei Aminocapronsäure als Reaktionskomponente ist eine Induktionsperiode meßbar nicht vorhanden, beide Funktionen verlaufen über den meßbaren Bereich konkav gegen die Zeitabszisse. Die Kettenzahl-Zeit-Funktionen durchlaufen bei Wasser ein Maximum und besitzen drei Wendepunkte; mit steigenden Wassermengen verschieben sich die Maxima nach kürzeren Reaktionszeiten und werden höher und schmaler; bei Aminocapronsäure liegt gegenüber der gleichen Anfangsmenge Wasser über einen relativ großen Anfangsbereich eine wesentlich größere Kettenzahl vor, die jedoch nicht durch einen erhöhten Aminocapronsäureanteil zu deuten ist. Aus diesem Befund heraus wird eine Erklärung für die Wirkungsweise allgemein von sog. Einbaukatalysatoren hergeleitet.Die Polymerisationsreaktion endet in einem Gleichgewicht. Die Reaktionsverläufe bei Wasser und bei derselben Anfangsmenge Aminocapronsäure in Molen erreichen im Gleichgewicht gleiche Werte.4. Mitteilung: F. Wiloth, Z. physikal. ChemieM. F. 5, 66 (1955)Zwischen dem Institut für Celluloseforsehung der AKU in Utrecht (Dr. P. H. Hermans), dem Kunststoffen Instituut TNO in Delft (Professor Dr. A. J. Stayermann) und unserem eigenen Forsehungsinstitut der VGF (Dr. E. Iteisenberg) hat ein Austausch yon Forsehungsergebnissea und Gedanken fiber die-Caprolaetampolymerisation stattgefunden. Für die fruchtbaren Diskussionen möchten Herrn Dr. Heisenberg und ieh insbesondere Herrn Dr. Hermans und seinen Mitarbeitern danken.Für die Genehmigung zur Veröffentlichung der vorhegenden Arbeit möchte ieh dem Vorstand der Glanzstoff-Fabriken AG., Wuppertal, aueh an dieser Stelie danken.