Synthesis,Crystal Structure,and Thermal Behaviors of 3‐Nitro‐1,5‐bis(4,4′‐dimethylazide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP)

The energetic material, 3‐nitro‐1,5‐bis(4,4′‐dimethyl azide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP), was firstly synthesized by means of Click Chemistry using 1,5‐diazido‐3‐nitrazapentane as main material. The structure of NDTAP was confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy; mass spectrometry, and elemental analysis. The crystal structure of NDTAP was determined by X‐ray diffraction. It belongs to monoclinic system, space group C2/c with crystal parameters a=1.7285(8) nm, b=0.6061(3) nm, c=1.6712(8) nm, β=104.846(8)°, V=1.6924(13) nm³, Z=8, μ=0.109 mm⁻¹, F(000)=752, and D_c=1.422 g cm⁻³. The thermal behavior and non‐isothermal decomposition kinetics of NDTAP were studied with DSC and TG‐DTG methods. The self‐accelerating decomposition temperature and critical temperature of thermal explosion are 195.5 and 208.2 °C, respectively. NDTAP presents good thermal stability and is insensitive.     

Generation of 3‐monochloro‐1,2‐propanediol and related materials from tri‐, di‐, and monoolein at deodorization temperature

Heating tests of pure tri‐, di‐, and monoolein (TO, DO, and MO, respectively) with and without the addition of tetrabutylammonium chloride as a chloride source at 240°C revealed the characteristic reactions that generate 3‐monochloro‐1,2‐propanediol‐related materials (3‐MCPD‐RM) in each acylglycerol. 3‐MCPD‐RM were formed mainly from DO and MO, with only a small amount from TO. Glycidyl ester was the predominant class of 3‐MCPD‐RM generated from both DO and MO, and was increased continuously throughout the heating period with comparable rates in both DO and MO, which also generated 3‐MCPD esters with chloride in a short completion time with an achieved level that was fourfold higher for MO than for DO. The production of free glycidol and 3‐MCPD was confirmed only in heated MO, but not from TO and DO, in a closed heating system, although these compounds were never detected in oils heated under simulated distillation conditions using a gas stream. In a closed system, both free glycidol and 3‐MCPD were increased throughout the heating period, which differed from the esters. Since an interesterification reaction, which produced free glycerol, was observed only in heated MO, free glycerol might be one of the precursors for those free forms. For clarification, further investigation is required.     

An Ab Initio Theoretical Study of 2,4,6‐Trinitro‐1,3,5‐Triazine, 3,6‐Dinitro‐1,2,4,5‐Tetrazine,and 2,5,8‐Trinitro‐Tri‐s‐Triazine

In order to evaluate 2,4,6‐trinitro‐1,3,5‐triazine (TNTAz), 3,6‐dinitro‐1,2,4,5‐tetrazine (DNTAz), and 2,5,8‐trinitro‐tri‐s‐triazine (TNTsTAz), the geometries of these compounds have been fully optimized employing the B3LYP density functional method and the AUG‐cc‐pVDZ basis set. The accurate gas phase enthalpies of formation have been obtained by using the atomization procedure and designing isodesmic reactions in which the parent rings are not destroyed. Based on B3LYP/AUG‐cc‐pVDZ calculated geometries and natural charges, the crystal structures have been predicted using the Karfunkel–Gdanitz method. Computed results show that there exists extended conjugation over the parent rings of these compounds. More energy content is reserved in DNTAz than in both TNTAz and TNTsTAz. The title compounds are much more sensitive than 1,3,5‐trinitrobenzene. The calculated detonation velocity of DNTAz reaches 9.73–9.88 km s⁻¹, being larger than those of CL‐20 and TNTAz. TNTsTAz has no advantage over the widely used energetic compounds such as RDX and HMX.     

Ene‐Carbonyl Reductive Coupling for the Synthesis of 3,3‐Disubstituted Phthalide, 3‐Hydroxyisoindolin‐1‐one and 3‐Hydroxyoxindole Derivatives

An efficient method for the synthesis of three classes of heterocyclic derivatives such as 3,3‐disubstituted phthalides, 3‐hydroxyisoindolin‐1‐ones and 3‐hydroxyoxindoles, is reported. In the presence of the simple reductive system, zinc (Zn)/ammonia (NH₃) [or zinc‐copper (Zn‐Cu)/ammonia], a wide range of alkenes including acrylates, acrylonitrile, acrylamide and vinyl sulfoxide underwent reductive coupling with methyl 2‐acylbenzoates and subsequent lactonization to provide 3,3‐disubstituted phthalides in good to high yields at ambient temperature. In a similar manner, 3‐hydroxyisoindolin‐1‐one and 3‐hydroxyoxindole derivatives could also be easily prepared by direct reductive coupling of phthalimides and N‐substituted isatins with activated alkenes, respectively. Application of this methodology towards the synthesis of 1‐naphthol derivatives on a gram scale is also depicted. Furthermore, the intramolecular phthalimides–ene reductive coupling afforded the respective cyclization products with high diastereoselectivity.

     

Preparation and properties of organosoluble,colorless, and high‐pretilt‐angle polyimides based on an alicyclic dianhydride and long‐main‐chain alkyl‐group‐containing diamines

Alicyclic polyimides (PIs) were prepared from 3‐carboxylmethyl‐cyclopentane‐1,2,4‐tricarboxylic acid dianhydride and α,ω‐di(4‐aminophenoxyl)alkanes. These PIs possessed good solubility in aprotic, strongly polar solvents such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethyl formamide, and m‐cresol. They possessed high transparency in visible wavelengths and were almost colorless. The pretilt angle of a liquid‐crystal display with these PIs as the alignment layer increased linearly as the length of the alkyloxy groups increased; it was close to 5° for the PI samples PI‐10 and PI‐12. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2814–2820, 2001     

Miscibility,thermal behaviour,morphology and mechanical properties of binary blends of poly[(R)‐3‐hydroxybutyrate] with poly(γ‐benzyl‐L‐glutamate)+

The miscibility, thermal behaviour, morphology and mechanical properties of poly[(R)‐3‐hydroxybutyrate] (PHB) with poly(γ‐benzyl‐L ‐glutamate) (PBLG) are investigated by means of differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests. The DSC results show that PHB and PBLG are immiscible in the melt state. Such immiscibility also exists in the amorphous state due to a clear two‐phase separated structure observed by SEM measurements. The blend samples with different thermal history, namely as original and melt samples separately, display differences in thermal behaviour such as the DSC scan profile, the crystallinity and the melting temperature of PHB. The crystallization of PHB both from the molten state and the amorphous state is retarded on addition of the second component. The SEM measurements reveal that a phase inversion occurs between the PHB/PBLG (60/40) and PHB/PBLG (40/60) blends. Except for the PHB/PBLG (40/60) blend, a microphase separated structure is observed for all blend compositions. The mechanical properties vary considerably with blend composition. Compared with pure components, the PHB/PBLG (20/80) blend shows a certain improvement in mechanical properties. © 2001 Society of Chemical Industry     

Carbon dioxide sorption and diffusion in poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐CO‐3‐hydroxyvalerate)

CO₂ sorption and diffusion in poly(3‐hydroxybutyrate) and three poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) copolymers were investigated gravimetrically at temperatures from 25° to 50°C and pressures up to 1 atm. The sorption behavior proved to be linear for all the copolymers studied. An additional set of measurements performed in a pressure decay apparatus at 35°C showed that the linearity could be extrapolated to pressures up to 25 atm. The sorption results obtained from both techniques were in good agreement. The poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) sorption kinetics were increasingly non‐Fickian at the higher temperatures, thus preventing the calculation of diffusion coefficients above 35°C. Interestingly, this was not the case for poly(3‐hydroxybutyrate), and diffusion coefficients and permeabilities could be calculated at all of the investigated temperatures. The 35°C permeabilities were fairly low, which is attributed to the high degree of crystallinity of this polyester family. Finally, the poly(3‐hydroxybutyrate) barrier properties against CO₂ are successfully compared with those of some selected common thermoplastics. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2391–2399, 1999     

Water transport properties in poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) biopolymers

Water sorption and diffusion have been investigated in poly(3‐hydroxybutyrate) (PHB) and three poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) copolymers [P(HB‐HV)] by means of a Cahn electromicrobalance. Permeability of these samples have been determined using a gravimetric permeation cell. Two experimental setups were used for the gravimetric sorption measurements, under dynamic and static conditions, respectively. The differences observed in the results obtained using these techniques are discussed. The sorption measurements have evidenced the tendency of water molecules to form aggregates or clusters in the polymer. In addition, the static sorption method revealed the potential of PHB and P(HB‐HV) to undergo molecular relaxations, eventually leading to a partial desorption of the previously sorbed water after an induction period. The clustering effect was adequately described by the polycondensation model. On the other hand, the interpretation of the diffusivity in terms of mobility coefficients has revealed a competition between a plasticization effect and clustering. As a whole, water transport properties in PHB and its copolymers can be considered to be very close in magnitude to those of common thermoplastics such as PVC and PET. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 455–468, 1999     

Thermogravimetric analysis of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)

The thermal degradation of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(HB‐HV)] was studied using thermogravimetry (TG). In the thermal degradation of PHB, the temperature at the onset of weight loss (T_o) was derived by T_o = 0.97B + 259, where B represents the heating rate (°C/min). The temperature at which the weight loss rate was maximum (T_p) was T_p = 1.07B + 273, and the final temperature (T_f) at which degradation was completed was T_f = 1.10B + 280. The percentage of the weight loss at temperature T_p (C_p) was 69 ± 1% whereas the percentage of the weight loss at temperature T_f (C_f) was 96 ± 1%. In the thermal degradation of P(HB‐HV) (7:3), T_o = 0.98B + 262, T_p = 1.00B + 278, and T_f = 1.12B + 285. The values of C_p and C_f were 62 ± 7 and 93 ± 1%, respectively. The derivative thermogravimetric (DTG) curves of PHB confirmed only one weight loss step change because the polymer mainly consisted of the HB monomer only. The DTG curves of P(HB‐HV), however, suggested multiple weight loss step changes; this was probably due to the different evaporation rates of the two monomers. The incorporation of 10 and 30 mol % of the HV component into the polyester increased the various thermal temperatures (T_o, T_p, andT_f) by 7–12°C (measured at B = 20°C/min). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2237–2244, 2001     

Biodegradable poly(ester‐ether)s: ring‐opening polymerization of D,L‐3‐methyl‐1,4‐dioxan‐2‐one using various initiator systems

The synthesis and detailed characterization of racemic 3‐methyl‐1,4‐dioxan‐2‐one (3‐MeDX) are reported. The bulk ring‐opening polymerization of 3‐MeDX, to yield a poly(ester‐ether) meant for biomedical applications, in the presence of various initiators such as tin(II) octanoate, tin(II) octanoate/n‐butyl alcohol, aluminium tris‐isopropoxide and an aluminium Schiff base complex (HAPENAlOⁱPr) under varying experimental conditions is here detailed for the first time. Polymerization kinetics were investigated and compared with those of 1,4‐dioxan‐2‐one. The studies reveal that the rate of polymerization of 3‐MeDX is less than that of 1,4‐dioxan‐2‐one. Experimental conditions to achieve relatively high molar masses have been established. Thermodynamic parameters such as enthalpy and entropy of 3‐MeDX polymerization as well as ceiling temperature have been determined. Poly(D ,L ‐3‐MeDX) is found to possess a much lower ceiling temperature than poly(1,4‐dioxan‐2‐one). Poly(D ,L ‐3‐MeDX) was characterized using NMR spectroscopy, matrix‐assisted laser desorption ionization mass spectrometry, size exclusion chromatography and differential scanning calorimetry. This polymer is an amorphous material with a glass transition temperature of about ?20 °C. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxy‐ ethylamino)propoxy]propyl}polydimethylsiloxane

A novel synthesis path for the monotelechelic polydimethylsiloxane with a diol‐end group, α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxyethylamino)propoxy]propyl}polydimethylsiloxane, is described in this article. The preparation included three steps, which were anionic ring‐opening polymerization, hydrosilylation, and epoxy addition. The structure and polydispersity index of the products were analyzed and confirmed by FTIR, ¹H NMR, ¹³C NMR, H? H, and C? H. Correlated Spectroscopy and gel permeation chromatography. The results demonstrated that each step was successfully carried out and the targeted products were accessed in all cases. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of Nano‐γ‐Ferric Oxide by Thermolysis of the 2‐Mercapto‐5‐Methylpyridine‐N‐Oxide‐Iron(III) Complex via Factorial Design

2‐Mercapto‐5‐methylpyridine‐N‐oxide (MMPNO) and its sodium salt (NaMMPNO) were synthesized. The reaction of the latter with Fe³⁺ generates Fe(MMPNO)₃ chelate. The thermolysis of this chelate at 350 °C yielded highly pure reddish‐brown γ‐Fe₂O₃ nanocrystallites with an average particle size of 6.2 nm, a particle size range of 4.2 to 14.8 nm, and a specific surface area of 51.5 m²g^–1. The thermolysis process was optimized using the 2² fractional design. Quantitative tests and characterization of products were carried out by UV‐vis spectroscopy, XRD, LLS, SEM, TGA, BET, TEM, FT‐IR, elemental microanalysis, and classical analytical measurements.     

Crystallization kinetics and melting behaviour of microbial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)

Isothermal and non‐isothermal crystallization kinetics of microbial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) [P(3HB‐3HHx)] was investigated by differential scanning calorimetry (DSC) and ¹³C solid‐state nuclear magnetic resonance (NMR). Avrami analysis was performed to obtain the kinetic parameters of primary crystallization. The results showed that the Avrami equation was suitable for describing the isothermal and non‐isothermal crystallization processes of P(3HB‐3HHx). The equilibrium melting temperature of P(3HB‐3HHx) and its nucleation constant of crystal growth kinetics, which were obtained by using the Hoffman–Weeks equation and the Lauritzen–Hoffmann model, were, respectively, 121.8 °C and 2.87 × 10⁵ K² when using the empirical ‘universal’ values of U* = 1500 cal mol^?1. During the heating process, the melting behaviour of P(3HB‐3HHx) for both isothermal and non‐isothermal crystallization showed multiple melting peaks, which was the result of melting recrystallization. The lower melting peak resulted from the melting of crystals formed during the corresponding crystallization process, while the higher melting peak resulted from the recrystallization that took place during the heating process. Copyright © 2005 Society of Chemical Industry     

Determination of total 3‐chloropropane‐1,2‐diol (3‐MCPD) in edible oils by cleavage of MCPD esters with sodium methoxide

A method for the determination of total 3‐chloropropane‐1,2‐diol (3‐MCPD) in edible fats and oils was presented. 3‐MCPD was released from 3‐MCPD fatty acid esters by transesterification with NaOCH₃/methanol. After derivatization with phenylboronic acid, 3‐MCPD was determined by GC‐MS. Deuterium‐labeled 3‐MCPD was used as internal standard. In a model experiment, it was shown that acidic hydrolysis with methanol/sulfuric acid, which is normally used for the release of 3‐MCPD from its esters, can cause problems because under acidic conditions additional 3‐MCPD can be formed. No additional 3‐MCPD was formed using NaOCH₃/methanol for transesterification. Eleven samples of cold‐pressed and refined safflower oils were analyzed with this method. Levels of total 3‐MCPD were in the range from <100 up to 3200 µg/kg.     

Synthesis and swelling properties of 2‐hydroxyethyl methacrylate‐co‐1‐vinyl‐3‐(3‐sulfopropyl)imidazolium betaine hydrogels

A series of 2‐hydroxyethyl methacrylate/1‐vinyl‐3‐(3‐sulfopropyl)imidazolium betaine (HEMA/VSIB) copolymeric gels were prepared from various molar ratios of HEMA and the zwitterionic monomer VSIB. The influence of the amount of VSIB in copolymeric gels on their swelling behavior in water and various saline solutions at different temperatures and the drug‐release behavior, compression strength, and crosslinking density were investigated. Experimental results indicated that the PHEMA hydrogel and the lower VSIB content (3%) in the HEMA/VSIB gel exhibited an overshooting phenomenon in their dynamic swelling behavior, and the overshooting ratio decreased with increase of the temperature. In the equilibrium water content, the value increased with increase of the VSIB content in HEMA/VSIB hydrogels. In the saline solution, the water content for these gels was not affected by the ion concentration when the salt concentration was lower than the minimum salt concentration (MSC) of poly(VSIB). When the salt concentration was higher than the MSC of poly(VSIB), the deswelling behavior of the copolymeric gel was more effectively suppressed as more VSIB was added to the copolymeric gels. However, the swelling behavior of gels in KI, KBr, NaClO₄, and NaNO₃ solutions at a higher concentration would cause an antipolyelectrolyte phenomenon. Besides, the anion effects were larger than were the cation effects in the presence of a common anion (Cl^?) with different cations and a common cation (K⁺) with different anions for the hydrogel. In drug‐release behavior, the addition of VSIB increased the drug‐release ratio and the release rate. Finally, the addition of VSIB in the hydrogel improved the gel strength and crosslinking density of the gel. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2888–2900, 2001     

Rosiglitazone,but Not Epigallocatechin‐3‐Gallate,Attenuates the Decrease in PGC‐1α Protein Levels in Palmitate‐Induced Insulin‐Resistant C2C12 Cells

Alteration of lipid metabolism is an important mechanism for the treatment of insulin resistance. PGC‐1α, a key regulator of mitochondrial biogenesis and function, plays an important role in the improvement of insulin sensitivity by increasing fatty acids β‐oxidation. In the present study, the effects of epigallocatechin‐3‐gallate (EGCG), an anti‐obesity agent and enhancer of lipid catabolism, on PGC‐1α protein expression was examined and compared with anti‐diabetic drug rosiglitazone (RGZ). After differentiation of C2C12 myoblasts to myotubes, insulin resistance was induced by palmitate treatment. Then the expression of the PGC‐1a gene and glucose uptake were evaluated before and after treatment with RGZ and EGCG. Palmitate treatment significantly decreased PGC‐1α protein expression in C2C12 cells (P < 0.05). RGZ could restore the expression of PGC‐1α in palmitate treated cells (P > 0.05), while EGCG had no significant effect on the expression of this gene (P < 0.05). RGZ and EGCG significantly improved glucose uptake (by 2‐ and 1.54‐fold, respectively) in myotubes treated with palmitate. These data suggest that RGZ and EGCG both exert their anti‐diabetic activity by increasing insulin sensitivity, but with different molecular mechanisms. This effect of RGZ, unlike EGCG, is mediated, at least partly, by increasing PGC‐1α protein expression.     

N‐Bromosuccinimide‐Mediated Radical Cyclization of 3‐Arylallyl Azides: Synthesis of 3‐Substituted Quinolines

Visible light irradiation of N‐bromosuccinimide serves as an effective means to convert methyl 2‐(azidomethyl)‐3‐arylpropenoates and 2‐(azidomethyl)‐3‐arylacrylonitriles to the corresponding iminyl radicals via α‐hydrogen abstraction and subsequent extrusion of dinitrogen. Thus formed iminyl radicals then undergo intramolecular ortho attack on the aryl ring, affording methyl quinoline‐3‐carboxylates and quinoline‐3‐carbonitriles respectively.

     

Intramolecular Photochemical Cross‐Coupling Reactions of 3‐Acyl‐2‐haloindoles and 2‐Chloropyrrole‐3‐carbaldehydes with Substituted Benzenes

Highly efficient syntheses of indolo[2,1‐a]isoquinolines, indolo[2,1‐a][2]benzazepines, pyrrolo[2,1‐a]isoquinolines and pyrrolo[1,2‐a]benzazepines in excellent yields have been achieved by the intramolecular photochemical cross‐coupling reactions of 3‐acyl‐2‐halo‐N‐(ω‐arylalkyl)indoles and 2‐chloro‐N‐(ω‐arylalkyl)pyrrole‐3‐carbaldehydes in acetone. A new heterocyclic ring system – pyrrolo[1,2‐d][1,4]benzoxazepine – has also been constructed for the first time in this work by the photocyclization of 2‐chloro‐N‐(2‐phenoxyethyl)pyrrole‐3‐carbaldehyde.     

Thermal analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) irradiated under vacuum

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was irradiated by ⁶⁰Co γ‐rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one‐step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight‐loss step change. The onset degradation temperature (T_o) and the temperature of maximum weight‐loss rate (T_p) of control and irradiated PHBV were in line with the heating rate (°C min^?1). T_o and T_P of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that ⁶⁰Co γ‐radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (T_m) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry