New type phosphorous amides derived from protected monosaccharides

Three synthetic routes to hydrogen phosphoramidites derived from protected hydrocarbons containing one free secondary hydroxy group are explored: phosphorylation with (diethylamido)phosphorous dichloride, acidolysis of tetraalkyldiamides derived from sugars, and phosphorylation with phosphorous tetraalkyldiamides. The last route was found to be preferred. Some properties of the prepared dialkylamidoglycophosphites were studied: stability, phosphorylating activity, and behavior in oxidation reactions.     

Thermal stability and biodegradation of novel D-mannose based glycopolymers

This paper presents the thermal stability and biodegradability testing of new glycopolymers obtained by copolymerization of a novel D-mannose based oligomer with 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate. The thermal analysis of these glycopolymers was investigated by thermogravimetry and the glass transition temperature was determined by DSC. While the acrylate derived glycopolymer has values of the glass transition temperature below 0 °C, the methacrylate derivative has positive values, above 50 °C. The biodegradation studies of the glycopolymers were carried out in a liquid medium, using pure cultures of two microorganisms, Zymomonasmobilis and Trichodermareesei. The weight losses of the new plastic materials were significant (almost 40%) and the best results were assessed for the 2-hydroxypropyl acrylate glycopolymer in the presence of both Z. mobilis and T. reesei. Microscopy showed that both microorganisms were present on the surface of the new glycopolymers and developed small colonies while modifying their surface. The changes inside the morphology of the polymeric materials structure were drastic and were studied via SEM analysis.     

Thermal analysis of a polymorphic azo dye derived from 2-amino-5-nitrothiazole

An azo dye, derived from 2-amino-5-nitrothiazole and a substituted N,N-dimethyl aniline, was studied by various techniques. Two sets of proton signals were obtained by NMR in CDCl₃ solution, suggesting that two polymorphs coexist, however, only one set of signals is observed in DMSO solution. Differential scanning calorimetry and thermogravimetric analysis were used to confirm the existence of two forms. The events registered during thermal treatment of a sample were assigned to a glass transition, recrystallization and fusion of crystalline compounds. Hot-stage microscopy was used to obtain images of the dye samples at various stages of the heating program and these observations support the interpretation of the calorimetric results.     

Generation of well‐defined clickable glycopolymers from aqueous RAFT polymerization of isomaltulose‐derived acrylamides

Original carbohydrate‐based acrylamides bearing one azide group in C‐2 or C‐6 position namely, 2‐[(2‐deoxy‐2‐azido‐α‐D ‐mannopyranosyloxy)ethanamido]‐ethyl acrylamide (II) and 2‐[(6‐deoxy‐6‐azido‐α‐D ‐glucopyranosyloxy)ethanamido]‐ethyl acrylamide (III), and their azide‐free analogue, 2‐[(α‐D ‐glucopyranosyloxy)ethanamido]‐ethyl acrylamide (I), have been designed. Whereas the reversible addition fragmentation chain transfer (RAFT) process ensured the preparation of well‐defined glycopolymers from I, the polymerization of monomers II and III proved to be challenging at temperatures compatible with a thermally initiated radical process, due to the presumed concomitant 1,3‐cycloaddition reactions between the azide and the acrylamide moieties. In contrast to III, for which no polymer could be obtained under any conditions, performing the RAFT polymerization of II at 30 °C clearly favored the radical polymerization and conferred a controlled character to the process, affording well‐defined azide‐functionalized glycopolymers and block copolymers. The presence of numerous azide moieties was finally exploited to introduce carbohydrates onto the glycopolymer backbone through copper catalyzed azide‐alkyne cycloaddition. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Controlled synthesis of new amphiphilic glycopolymers with liquid crystal grafts

A cholesterol‐based liquid crystal monomer, diethylene glycol cholesteryl ether acrylate (DEGCholA), has been successfully polymerized by atom transfer radical polymerization (ATRP) for the first time. Appropriate experimental conditions to control the polymerization of DEGCholA have been investigated using a model initiator (ethyl 2‐bromoisobutyrate) in tetrahydrofuran (THF) or toluene at 60 °C. Well‐controlled ATRP of DEGCholA was obtained using N,N,N′,N′,N″‐pentamethyldiethylenetriamine as ligand in THF at 60 °C. These conditions were then applied to initiate the ATRP of DEGCholA from multifunctional macroinitiators based on dextran. Using a protection/deprotection synthetic scheme, novel graft glycopolymers (Dex‐g‐PDEGCholA) have been synthesized. The mesomorphic properties of DEGCholA, PDEGCholA, and Dex‐g‐PDEGCholA have been studied by thermal polarizing optical microscopy, differential scanning calorimetry, and X‐ray scattering. PDEGCholA and Dex‐g‐PDEGCholA show an interdigitated smectic A phase (SmA_d) between T_g (～30 °C) and around 170 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3829–3839     

Thermal analysis of cyclic carbonation behavior of CaO derived from carbide slag at high temperature

In this work, CaO derived from the carbide slag (CaO?Ccarbide slag) as a kind of typical industrial waste was used to capture CO₂ during the calcination/carbonation cycles. The carbonation kinetics and cyclic carbonation behavior of CaO?Ccarbide slag were investigated in a thermogravimetric analyzer. The chemical reaction activation energy and the product layer diffusion activation energy for carbonation of CaO?Ccarbide slag are 12.46 and 36.83?kJ?mol^?1, respectively, which are significantly less than those for carbonation of CaO derived from the limestone (CaO?Climestone). CaO?Ccarbide slag shows higher carbonation conversion than CaO?Climestone after enough reaction time and at the same number of cycles. Moreover, the calcination temperature and CO₂ concentration in the carbonation atmosphere have important effect on the carbonation behavior of CaO?Ccarbide slag. The BET surface area of CaO?Ccarbide slag is 1.6 times as large as that of CaO?Climestone after 1 cycle and the average pore size of CaO?Ccarbide slag is much smaller. In addition, the carbide slag contains much more Al₂O₃ than most of the limestones. These are reasons why carbide slag as a precursor can retain greater carbonation conversion than limestone in calcination/carbonation cycles.     

Thermal investigation of biodiesel blends derived from rapeseed oil

Over the last few years, the production of biodiesel from vegetable oil has significantly increased in Romania due to its obligatory use in the composition of diesel fuel. In this study, biodiesel from rapeseed oil was produced using methanol and a base catalyst. Four samples of biodiesel/diesel blends were prepared for analysis to determine the main thermal decomposition processes and calorimetric events. The thermal profiles were compared to reference diesel. The data obtained on the Thermogravimetry/Differential thermogravimetry and DTA curves show the quality of biodiesel/diesel blends and the possibility that the fuel be used in diesel engines. It was found that biodiesel blends with higher percentage of biodiesel in their compositions were more thermally stable than diesel fuel.     

Thermal degradation of flame-retardant compounds derived from castor oil

Castor oil is a non-edible plant oil produced in a large quantity annually. It is a triglyceride of primarily (approximately 90%) ricinoleic acid. The acid residues contain both a hydroxyl group and a double bond which permit ready functionalization. The hydroxyl group may be converted to phosphorus esters of varied structure while the unsaturation readily undergoes addition of bromine. Derivatives of castor oil containing phosphorus, bromine, or phosphorus and bromine have been prepared and fully characterized using spectroscopic and thermal methods. The thermal stability and mode of degradation for these compounds have been assessed using thermogravimetry and infrared spectroscopy. The primary mode of degradation for the phosphorus esters is elimination of the corresponding phosphorus acid (phosphates more readily than phosphonates). Brominated castor oil undergoes thermally induced dehydrobromination at relatively modest temperatures and this promotes dehydration (at temperatures well below that required for dehydration of unmodified castor oil). Brominated phosphorus esters of castor oil undergo degradation initiated by dehydrobromination.

     

Two new compounds derived from bufalin

The biotransformation of bufalin by cell suspension cultures of Platycodon grandiflorus was investigated and two new biotransformed products were obtained,which was 3-epi-telocinobufagin and 3-epi-bufalin-3-O-β-D-glucoside.     

Gas chromatographic analysis of free monosaccharides in milk

Summary Three silylation methods for the gas chromatographic analysis of ketohexoses have been compared for yield and tautomeric composition of trimethylsilyl ethers. One of them has been applied to the analysis of milk monosaccharides and evaluated for precision and accuracy. Of the different stationary phases employed, OV-215 and AT-1000 were the best suited to resolve the TMS ethers of the studied sugars.     

Thermal properties of polyurethanes derived from molasses before and after biodegradation

Polyurethane (PU) foams derived from molasses were placed in soil for various periods from 3 to 12 months. Thermal properties of PU's before and after biodegradation were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). Glass transition of PU's after 3 month's degradation was separated into two stages indicating that molecular chains of the original and decomposed portions move independently. Based on variation of glass transition temperature (T_g), heat capacity difference at T_g (δC_p), thermal degradation temperature and mass loss, the degradation mechanism of PU was established.     

A new boron-selective resin derived from guar gum

A boron-selective resin has been prepared by cross-linking of a natural plant hydrocolloid (the polysaccharide guaran from guar seeds). Concentration and separation of boron can be achieved on this resin through completing of boron with the cis-hydroxyl groups in the polymer. The method has been applied to the determination of boron.     

Thermal analysis of new hydrazinium(2+) hexafluoroantimonate

Hydrazinium(2+) hexafluoroantimonate was prepared by the reaction of N₂H₆F₂ with an excess of SbF₅ in anhydrous HF as solvent. The compound was characterized by chemical analysis and vibrational spectra. The X-ray powder photograph was indexed on the basis of a monoclinic cell witha=8.22(2),b=10.04(3),c=9.51(2) Å,=97.2(2)° andV=780 ų.The thermal decomposition study of N₂H₆(SbF₆)₂ showed that it decomposed to gaseous components through an intermediate, a mixture of N₂H₅SbF₆ and NH₄SbF₆. In the DSC curve, a strong endothermic effect and medium exothermic and endothermic effects were observed in the range 25–600°C.

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Zusammenfassung Mit der Reaktion von N₂H₆F₂ mit einem Überschuss von SbF₅ in wasserfreiem HF als Lösungsmittel wurde Hydrazinium(2+)hexafluoroantimonat hergestellt. Die Verbindung wurde durch Elemetaranalyse und Schwingungsspektren charakterisiert. Röntgendiffraktionsaufnahmen ergaben ausgehend von einer monoklinen Zellea=8.22(2),b=10.04(3),c=9.51(2) Å,=97.2° undV=780 ų.Die Untersuchung der thermischen Zersetzung von N₂H₆(SbF₆)₂ ergab, dass es sich diese Verbindung über eine Zwischenstufe, ein Gemisch aus N₂H₅SbF₆ und NH₄SbF₆, in gasförmige Komponenten zersetzt. In der DSC-Kurve können im Bereich 25–600°C ein starker endothermer sowie mittelstarke exotherme und endotherme Effekte beobachtet werden.

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We thank Miss B. Sedej for the chemical analysis and the Research Community of Slovenia for financial support.     

Thermal and spectral studies on complexes derived from tetradentate Schiff bases

Several new complexes of Schiff bases ligands H₄La and H₄Lb with transition metal ions such as Cr(III), Fe(III), Co(II) and Zn(II) are synthesized. Elemental analysis, infrared, UV–Vis and thermal analysis, as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. A square planar geometry is suggested for Zn(II) complexes, while an octahedral geometry suggested for the Cr(III), Fe(III) and Co(II) complexes. The thermal decomposition of complexes was found to be first order reaction and the thermodynamic parameters corresponding to the different decomposition steps were reported.     

Thermal analysis and crystallization from melts

The growth of atenolol, pindolol and betaxolol hydrochloride from melt was investigated by differential scanning calorimetry (DSC) and polarized light thermal microscopy (PLTM). Phase transitions occurring on cooling and subsequent reheating runs performed between −160 °C and a temperature above the respective melting points were studied by DSC. The thermal cycles were also followed by PLTM. Details about the dynamic of the crystallization front taken from microscopic observations are given. An explanation of the results on the basis of molecular supramolecular recognition is advanced.     

Thermal analysis from a numerical aspect

This publication surveys the present state of thermal analysis from a numerical aspect. It deals with the applied methods and techniques, the substances studied, and the journals publishing papers on thermal analysis.

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Zusammenfassung In der Veröffentlichung wird ein Überblick über die gegenwärtige Situation der thermischen Analyse gegeben. Auf Grund von aus Thermal Analysis Abstracts entnommenen Daten werden die Anwendungsmethodik, die verschiedenen Techniken, die Untersuchungsmaterialien sowie die thermoanalytische Publikationen enthaltenden Zeitschriften zusammengefaßt.

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. Thermal Analysis Abstract , , , , .

     

Aromatic homo‐ and copolyesters from naturally occurring monosaccharides: PET and PEI analogs derived from L‐arabinitol and xylitol

The synthesis and characterization of new aromatic homo‐ and copolyesters based on l‐arabinitol and xylitol are described. These polymers were obtained by polycondensation reaction of the 2,3,4‐tri‐O‐methyl‐l‐arabinitol or 2,3,4‐tri‐O‐methyl‐xylitol, or their mixtures with ethylene glycol, with terephthaloyl chloride or isophthaloyl chloride in o‐dichlorobenzene or in the melt phase from the corresponding methyl phthalates. All the polymers were characterized by GPC, IR, and NMR. Their M_w values ranged between 11,500 and 46,500, with polydispersities from 1.5 to 2.3. They were found to be soluble in chloroform, but insoluble in water. In contrast with the homopolymers completely made with EG, they showed a significant hygroscopicity. DSC and TGA studies showed that the melting temperature of polyethylene terephthalate is depressed by the presence of pentitol units, whereas the thermal stability is kept above 350 °C. Only copolyesters containing 10% or less of pentitol units showed melting and produced X‐ray diffraction patterns characteristic of crystalline material. d‐Arabinitol‐based homopolyesters appeared to be more crystalline than those derived from xylitol and also presented a higher thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6394–6410, 2005