Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

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.     

Characterization of 4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine

4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine (DANT) was prepared with a 35 % yield from cyanuric chloride in a three step process. DANT was characterized by IR and NMR spectroscopy (¹H, ¹³C, ¹⁵N), single‐crystal X‐ray diffraction, and DTA. The crystal density of DANT is 1.849 g cm⁻³. The cyclization of one azido group and one nitrogen atom of the triazine group giving tetrazole was observed for DANT in a dimethyl sulfoxide solution using NMR spectroscopy. An equilibrium exists between the original DANT molecule and its cyclic form at a ratio of 7 : 3. The sensitivity of DANT to impact is between that for PETN and RDX, sensitivity to friction is between that for lead azide and PETN, and sensitivity to electric discharge is about the same as for PETN. DANT′s heat of combustion is 2060 kJ mol⁻¹.     

Synthesis of novel phosphorous‐containing biphenol, 2‐(5, 5‐dimethyl‐4‐phenyl‐2‐oxy‐1,3,2‐dioxaphosphorin‐6‐yl)‐1,4‐benzenediol and its application as flame‐retardant in epoxy resin

A novel phosphorous‐containing biphenol, 2‐(5,5‐dimethyl‐4‐phenyl‐2‐oxy‐1,3,2‐dioxaphosphorin‐6‐yl)‐ 1,4‐benzenediol (DPODB), was prepared by the addition reaction between 5,5‐dimethyl‐4‐phenyl‐2‐oxy‐1,3,2‐dioxaphosphorinane phosphonate (DPODP) and p‐benzoquinone (BQ). The compound (DPODB) was used as a reactive flame retardant in o‐cresol formaldehyde novolac epoxy resin (CNE) for electronic application. The structure of DPODB was confirmed by FTIR and NMR spectra. Thermal properties of cured epoxy resin were studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The flame retardancy of cured epoxy resins was tested by UL‐94 vertical test and achieved UL‐94 vertical tests of V‐0 grade (nonflammable). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3842–3847, 2006     

1‐Amino‐1‐hydrazo‐2,2‐dinitroethene – a Hazard Warning

1‐Amino‐1‐hydrazo‐2,2‐dinitroethene ( 2 ) has been observed to spontaneously decompose with considerable violence during storage. Its preparation and handling should be regarded as potentially hazardous.     

Synthesis of novel azo‐containing polyureas derived from 4‐[4′‐(2‐hydroxy‐1‐naphthylazo)phenyl]‐1,2,4‐triazolidine‐3,5‐dione

4‐[4′‐(2‐Hydroxy‐1‐naphthylazo)phenyl]‐1,2,4‐triazolidine‐3,5‐dione ( HNAPTD ) ( 1 ) has been reacted with excess amount of n‐propylisocyanate in DMF (N,N‐dimethylformamide) solution at room temperature. The reaction proceeded with high yield, and involved reaction of both N? H of the urazole group. The resulting bis‐urea derivative 2 was characterized by IR, ¹H‐NMR, elemental analysis, UV‐Vis spectra, and it was finally used as a model compound for the polymerization reaction. Solution polycondensation reactions of monomer 1 with Hexamethylene diisocyanate ( HMDI ) and isophorone diisocyanate ( IPDI ) were performed in DMF in the presence of pyridine as a catalyst and lead to the formation of novel aliphatic azo‐containing polyurea dyes, which are soluble in polar solvents. The polymerization reaction with tolylene‐2,4‐diisocyanate ( TDI ) gave novel aromatic polyurea dye, which is insoluble in most organic solvents. These novel polyureas have inherent viscosities in a range of 0.15–0.22 g dL^?1 in DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3177–3183, 2001     

A Highly Regioselective Preparation of 4‐Chloromethyl‐5‐methyl‐2‐aryl‐1,3‐oxazoles

A facile highly regioselective process is described for the formation of 4‐chloromethyl‐1,3‐oxazoles from 1,3‐oxazole N‐oxide/HCl salts. An explanation is presented for the high regioselectivity in deoxygenation‐chlorination using POCl₃ with HCl salts compared to the corresponding free N‐oxides. The method is quite general and the products are isolated by direct precipitation in all cases studied.     

Poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane‐poly(dimethylsiloxane) block copolymers

The heterofunctional condensation of 1,3‐dichloro‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane with dihydroxydiphenylsilane at various ratios of initial compounds in the presence of amines was carried out, and α,ω‐dihydroxy(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane oligomers with various degrees of condensation were obtained. Corresponding block copolymers were obtained by heterofunctional polycondensation of synthesized α,ω‐dihydroxy(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane oligomers with α,ω‐dichlorodimethylsiloxanes in the presence of amines. Thermogravimetry, gel permeation chromatography, differential scanning calorimetry, and wide‐angle X‐ray analysis were carried out on the synthesized block coplymers. Differential scanning calorimetry and wide‐angle X‐ray studies of these copolymers showed that their properties were determined by the ratio of the lengths of the flexible linear poly(dimethylsiloxane) and rigid poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane fragments in the main macromolecular chain. Two‐phase systems were obtained with specific flexible and rigid fragment length values in synthesized block copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3462–3467, 2006     

Silver Salt of 4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine – Characterization of this Primary Explosive

A new primary explosive, the silver salt of 4,6‐diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine (AgDANT), was synthesized and characterized. AgDANT was prepared with a 97 % yield and characterized by IR spectroscopy, single‐crystal X‐ray diffraction, and DTA. The crystal density of AgDANT is 2.530 g cm⁻³ and the molecule consists of a centro‐symmetric dimer with a high degree of planarity. The intramolecular Ag Ag distance is relatively low (331 pm) and can be considered as a strong argentophilic interaction. AgDANT is non‐hygroscopic and its solubility in water (1.27 mg in 100 mL at 23 °C) is on a similar level of solubility to that of silver azide. The sensitivity of AgDANT to impact is slightly higher than that for MF, sensitivity to friction is the same as for LA, and sensitivity to electric discharge is between that for LS and MF. Initiation efficiency of AgDANT was tested in electric detonators and compared to dextrinated lead azide (initiation efficiency of AgDANT is 40 mg for PETN secondary charge). The thermal resistance of detonators with AgDANT is satisfactory; all detonators were fully functional after exposure at 65 °C (30 d) and 85 °C (2 d).     

Microwave‐assisted rapid polycondensation reaction of 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione was reacted with 1 mol of acetyl chloride in dry N,N‐dimethylacetamide (DMAc) at ?15°C and 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione [4‐(4′‐acetanilido)‐1,2,4‐triazolidine‐3,5‐dione] (APTD) was obtained in high yield. The reaction of the APTD monomer with excess n‐isopropylisocyanate was performed at room temperature in DMAc solution. The resulting bis‐urea derivative was obtained in high yield and was finally used as a model for the polymerization reaction. The step‐growth polymerization reactions of monomer APTD with hexamethylene diisocyanate, isophorone diisocyanate, and tolylene‐2,4‐diisocyanate were performed under microwave irradiation and solution polymerization in the presence of pyridine, triethylamine, or dibutyltin dilaurate as a catalyst. Polycondensation proceeded rapidly, compared with conventional solution polycondensation; it was almost completed within 8 min. The resulting novel polyureas had an inherent viscosity in the range of 0.07–0.17 dL/g in dimethylformamide or sulfuric acid at 25°C. These polyureas were characterized by IR, ¹H‐NMR, elemental analysis, and thermogravimetric analysis. The physical properties and structural characterization of these novel polyureas are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2103–2113, 2004     

Lecithin‐enhanced biotransformation of cholesterol to androsta‐1,4‐diene‐3,17‐dione and androsta‐4‐ene‐3,17‐dione

A biotransformation process using Mycobacterium sp was studied for androsta‐1, 4‐diene‐3,17‐dione (ADD) and androsta‐4‐ene‐3,17‐dione (AD) production from cholesterol. Cholesterol has a poor solubility in water (～1.8 mg dm^?3 at 25 °C), which makes it difficult to use as the substrate for biotransformation. Lecithin is a mixture of phospholipids of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), which behave like surfactants and can form planar bi‐layer structures in an aqueous medium. Therefore, a small amount of lecithin (<1 g dm^?3) can be used to form stable colloids with cholesterol at a relatively high concentration (20 g dm^?3) in water. In this work, an energy density of 1000 J cm^?3 from sonication was provided to overcome the self‐association of cholesterol and to generate a stable lecithin–cholesterol suspension that could be used for enhanced biotransformation. The lecithin–cholesterol suspension was stable and could withstand typical autoclaving conditions (121 °C, 15 psig, 20 min). In contrast to conventional surfactants, such as Tween 80, that are commonly used to help solubilize cholesterol, lecithin did not change the surface tension of the aqueous solution nor cause any significant foaming problem. Lecithin was also biocompatible and showed no adverse effect on cell growth. Compared with the medium with Tween 80 as the cholesterol‐solubilizing agent, lecithin greatly improved the biotransformation process in regard to its final product yield (～59% w/w), productivity (0.127–0.346 g dm^?3 day^?1), ADD/AD ratio (6.7–8), as well as the long‐term process stability. Cells can be reused in repeated batch fermentations for up to seven consecutive batches, but then lose their bioactivity due to aging problems, possibly caused by product inhibition and nutrient depletion. © 2002 Society of Chemical Industry     

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.     

Organosoluble and light‐colored fluorinated polyimides derived from 5,5′‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy) phenyl]‐4,7‐methanohexahydroindan

A novel bis(ether amine) monomer, 5,5′‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]‐4,7‐methanohexahydroindan ( 2 ), was synthesized through the nucleophilic aromatic substitution reaction of 5,5′‐bis‐(4‐hydroxyphenyl)‐4,7‐methanohexahydroindan with 2‐chloro‐5‐nitrobenzotrifluoride to yield the intermediate dinitro compound, followed by catalytic reduction with hydrazine and Pd/C. A series of polyimides were synthesized from 2 and various aromatic dianhydrides using a standard two‐stage process with chemical or thermal imidization of poly(amic acid). All of these polymer films were soluble in amide‐type solvents above 10% w/v, had tensile strengths of 97–117 MPa, and the 10% weight loss temperature was above 464 °C with their residues exceeding 46% at 800 °C in nitrogen. Compared with the non‐fluorinated polyimides, the fluorinated series were observed to have lower dielectric constants (2.92–3.28 at 1 MHz) and lower moisture absorptions (0.15–0.43 wt%) as well as lower color intensity and better solubility. Copyright © 2006 Society of Chemical Industry     

Preparation of 1,3‐Diazido‐2‐Nitro‐2‐Azapropane from Urea

An alternative method to prepare 1,3‐diazido‐2‐nitro‐2‐azapropane (DANP), a promising liquid component for high‐energy condensed systems, is suggested and involves the following stages: (i) nitration of urea, (ii) condensation of the nitration product with formaldehyde, (iii) acylation (chlorination) of 1,3‐dihydroxy‐2‐nitro‐2‐azapropane, (iv) chlorination of 1,3‐diacetoxy‐2‐nitro‐2‐azapropane, and (v) azidation of the dichloro derivative to DANP. This synthesis method is selective and enables isolation of 1,3‐diazido‐2‐nitrazapropane devoid of impurities.     

Highly Selective Synthetic Method for 1,6‐Diols Bearing Enyne Functions: Development of 3,6‐Dianion Reagent of 1,2‐Hexadien‐4‐yne Using 1,6‐Dibromo‐2,4‐hexadiyne and Indium

The reaction of aldehydes and ketones with an organoindium reagent generated in situ from indium and 1,6‐dibromo‐2,4‐hexadiyne in the presence of lithium iodide in tetrahydrofuran (THF) selectively produced 1,6‐diols linked to an allenyne unit with complete regioselectivity and chemoselectivity through 1,2‐hexadien‐4‐yn‐3,6‐ylation, indicating that the organoindium acted as the 3,6‐dianion reagent of 1,2‐hexadien‐4‐yne.     

Synergistic extraction of rare earths(III) from chloride medium with mixtures of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate

The synergistic effect of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 (HPMBP, HA) and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate (DEHEHP, B) in the extraction of rare earths (RE) from chloride solutions has been investigated. Under the experimental conditions used, there was no detectable extraction when DEHEHP was used as a single extractant while the amount of RE(III) extracted by HPMBP alone was also low. But mixtures of the two extractants at a certain ratio had very high extractability for all the RE(III). For example, the synergistic enhancement coefficient was calculated to be 9.35 for Y³⁺, and taking Yb³⁺ and Y³⁺ as examples, RE³⁺ is extracted as RE(OH)A₂.B. The stoichiometry, extraction constants and thermodynamic functions such as Gibbs free energy change ΔG (?17.06 kJ mol^?1), enthalpy change ΔH (?35.08 kJ mol^?1) and entropy change ΔS (?60.47 J K^?1 mol^?1) for Y³⁺ at 298 K were determined. The separation factors (SF) for adjacent pairs of rare earths were calculated. Studies show that the binary extraction system not only enhances the extraction efficiency of RE(III) but also improves the selectivity, especially between La(III) and the other rare earth elements. Copyright © 2006 Society of Chemical Industry     

Regioselective Addition of Organometallic Reagents to 2‐(1‐Alkynyl)‐2‐alken‐1‐ones for an Efficient Synthesis of Substituted 1,2‐Allenyl Ketones

Highly substituted 1,2‐allenyl ketones can be easily and efficiently prepared from organometallic reagents and readily available 2‐(1‐alkynyl)‐2‐alken‐1‐ones. The synthetic application of 1,2‐allenyl ketone products was also showcased by palladium‐catalyzed further transformation.