Synthesis of [3,3′(4H,4′H)‐Bi‐2H‐1,3‐oxazine]‐4,4′‐diones and Their Hydrolysis

The [3,3′(4H,4′H)‐bi‐2H‐1,3‐oxazine]‐4,4′‐diones 3a – 3i were obtained by [2+4] cycloaddition reactions of furan‐2,3‐diones 1a – 1c with aromatic aldazines 2a – 2d (Scheme 1). So, new derivatives of bi‐2H‐1,3‐oxazines and their hydrolysis products, 3,5‐diaryl‐1H‐pyrazoles 4a – 4c (Scheme 3), which are potential biologically active compounds, were synthesized for the first time.     

Solvent‐free One‐pot Synthesis of 2,2′‐dithioxo‐[5,5′]bithiazolidinylidene‐4,4′‐diones

Solvent‐free one‐pot synthesis of 2,2′‐dithioxo‐[5,5′]bithiazolidinylidene‐4,4′‐dione (birhodanine) derivatives from the reaction of primary amines and carbon disulfide in the presence of dimethyl acetylene dicarboxylate has been reported.     

Synthesis of new 3,3′‐(1,4‐phenylene)bis(1,5‐diones) derivatives

Several 3,3′‐(1,4‐phenylene)bis(1,5‐diones) and their chalcone precursors have been prepared in good to excellent yield via aldol addition and Michael addition starting from 3‐acetyl‐2,5‐dimethylfuran or 3‐acetyl‐2,5‐dimethyl‐thiophene with terephthalaldehyde in the presence of appropriate base NaOH or lithium diisopropylamide. The kind and amount of alkali played a critical role in improving the reaction rates and yields of the products. J. Heterocyclic Chem., (2011).     

3,3′,5,5′‐Tetramethyl‐4,4′‐bipyrazole–pentafluorophenol (2/3)

In the title compound, 2C₁₀H₁₄N₄·3C₆HF₅O, one of the pentafluorophenol molecules resides on a mirror plane bisecting the O...F axis. The components aggregate by N—H...N, N—H...O and O—H...N hydrogen bonds involving equal disordering of the H atoms into molecular ensembles based on a 2:1 pyrazole–phenol cyclic pattern [O...N = 2.7768 (16) Å and N...N = 2.859 (2) Å], crosslinked into one‐dimensional columns via hydrogen bonding between the outer pyrazole groups and additional pentafluorophenol molecules. The latter yields a 1:1 pyrazole–phenol catemer with alternating strong O—H...N [2.5975 (16) Å] and weaker N—H...O [2.8719 (17) Å] hydrogen bonds. This is the first reported molecular adduct of a pentafluorinated phenol and a nitrogen base, and suggests the utility of highly acidic phenols and pyrazoles for developing hydrogen‐bonded cocrystals.     

Synthesis and characterization of photosensitive polyimides from methylthiomethyl-substituted 4,4′-diaminodiphenylmethanes and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride

A series of novel polyimides are synthesized by the reaction of 3,3′,4,4′-benzophenonete-tracarboxylic dianhydride (BTDA) with four methylthiomethyl-substituted aromatic diamines: 3-methylthiomethyl-4,4′-diaminodiphenylmethane ( I ), 3,3′-dimethylthiomethyl-4,4′-diaminodiphenylmethane ( II ), 3,3′,5-trimethylthiomethyl-4,4′-diaminodiphenylmethane ( III ), and 3,3′,5,5′-tetramethylthiomethyl-4,4′-diaminodiphenylmethane ( IV ) in refluxing m-cresol. The polyimide of diamine I and BTDA carrying only one pendant methylthiomethyl group in a repeating unit is readily soluble in m-cresol, chloroform, and polar aprotic solvents. Increasing the number of the pendant group results in higher solubility. These fully imidized polyimides are also intrinsically photosensitive. The fraction of photoreactive benzophenone sites that relates to the rate and degree of completion of photocrosslinking reaction increases systematically with the increase of the pendant group content. As the average number of the pendant group in a repeating unit reaches 3, 63% of benzophenone sites are found to be photoreactive. These methylthiomethyl-substituted polyimides possess moderate tensile strength which falls in the range of 67–81 MPa. As a result of the increase of methylthiomethyl content, this type of polyimide reveals higher glass transition temperature but lower thermal stability due to the considerable dimension of the pendant group and the ready cleavage nature of the C? S bond. © 1993 John Wiley & Sons, Inc.     

Synthesis and Characterization of Fluorinated Polyimide Derived from 3,3′‐Diisopropyl‐4,4′‐diaminodiphenyl‐3′′,4′′‐difluorophenylmethane

A novel aromatic diamine monomer, 3,3′‐diisopropyl‐4,4′‐diaminodiphenyl‐3′′,4′′‐difluorophenylmethane (PAFM), was successfully synthesized by coupling of 2‐isopropylaniline and 3,4‐difluorobenzaldehyde. The aromatic diamine was adopted to synthesize a series of fluorinated polyimides by polycondensation with various dianhydrides: pyromellitic dianhydride (PMDA), 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), 4,4′‐oxydiphthalic anhydride (ODPA) and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) via the conventional one‐step method. These polyimides presented excellent solubility in common organic solvents, such as N,N‐dimethylformamide (DMF), N,N‐dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP), chloroform (CHCl₃), tetrahydrofuran (THF) and so on. The glass transition temperatures (T_g) of fluorinated polyimides were in the range of 260–306°C and the temperature at 10% weight loss in the range of 474–502°C. Their films showed the cut‐off wavelengths of 330–361 nm and higher than 80% transparency in a wavelength range of 385–463 nm. Moreover, polymer films exhibited low dielectric properties in the range of 2.76–2.96 at 1 MHz, as well as prominent mechanical properties with tensile strengths of 66.7–97.4 MPa, a tensile modulus of 1.7–2.1 GPa and elongation at break of 7.2%–12.9%. The polymer films also showed outstanding hydrophobicity with the contact angle in the range of 91.2°–97.9°.     

Synthesis and characterization of thermally stable sulfonated polybenzimidazoles obtained from 3,3′‐disulfonyl‐4,4′‐dicarboxyldiphenylsulfone

A novel sulfonated aromatic diacid, 3,3′‐disulfonyl‐4,4′‐dicarboxyldiphenylsulfone (DSDCDPS), was successfully synthesized from 4,4′‐dimethyldiphenylsulfone by sulfonation and further oxidation. A series of sulfonated polybenzimidazoles (sPBI‐SS) with various sulfonation degrees was prepared from DSDCDPS, 4,4′‐sulfonyldibenzoic acid and 3,3′‐diaminobenzidine by solution copolycondensation in poly(phosphoric acid). The chemical structure of the resulting sPBI‐SS was confirmed by FTIR and ¹H NMR. The DSDCDPS‐based sPBI‐SS with the number‐average molecular weights of 32,000–55,000 were easy to dissolve in polar aprotic solvents such as DMF, DMSO, and DMAc, and could be cast into transparent, tough, and flexible membranes. The membranes presented good thermal stabilities (5% weight loss temperatures higher than 430 °C), and the thermal degradation activation energies of the sulfonic group of sPBI‐SS40 evaluated under N₂ by both Ozawa and Kissinger methods were 266.06 and 264.79 kJ/mol, respectively. The membranes also exhibited high storage moduli, glass transition temperatures (above 238 °C) and tensile strengths (～80 MPa), in addition to water uptakes (22.3–25.2%) and low swelling degrees (<14.0%). © 2005 Wiley Periodicals, Inc. J Polym Sci A: Polym Chem 43: 4363–4372, 2005     

Shear‐enhanced crystallization of a thermoplastic polyimide derived from 3,3′,4,4′‐oxydiphthalic dianhydride and 4,4′‐oxydianiline

The aim of this work is to investigate the effect of consecutive shear on the crystallization of an amorphous aromatic polyimide (PI) derived from 3,3 ′ ,4,4 ′ ‐oxydiphthalic dianhydride (3,3 ′ ,4,4 ′ ‐ODPA) and 4,4 ′ ‐oxydianiline (ODA). At 260 °C, the increase of shear rate or shear time leads to the increase of crystallinity. Indeed, increasing shear rate can also accelerate the crystallization behavior. Moreover, it was found that a new melting peak appeared at higher temperature for long time or high rate sheared sample. The enhancement of crystallization behavior appears directly linked to the increase of crystal thickness. Particularly, the effect of shear temperature was investigated, and the results revealed that the crystallization of the PI was more sensitive to shear at 260 °C, which was 10° above the glass transition temperature (250 °C) of the PI. Possible mechanism was proposed to illustrate the effect of consecutive shear on the crystallization of the PI polymer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2344–2349, 2007     

An Efficient Synthesis of 3,3′,4,4′‐Tetrahydro‐4,4′‐bibenzo[e][1,3]oxazine‐2,2′‐dione Derivatives with the Aid of Low‐valent Titanium

Synthesis of 3,3′,4,4′‐tetrahydro‐4,4′‐bibenzo[e][1,3]oxazine‐2,2′‐diones via reaction of salicylidendphenylhydrazone and triphosgene with the aid of low‐valent titanium reagent is described. This method has the advantages of accessible starting materials, good yields and short reaction time.     

Substituted 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Complexes of Zinc

The condensation reaction of 2,2′‐diamino‐4,4′‐dimethyl‐6,6'‐dibromo‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde as well as 5‐methoxy‐, 4‐methoxy‐, and 3‐methoxy‐2‐hydroxybenzaldehyde yields 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyl ( 1a ) as well as the 5‐, 4‐, and 3‐methoxy‐substituted derivatives 1b , 1c , and 1d , respectively. Deprotonation of substituted 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls with diethylzinc yields the corresponding substituted zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls ( 2 ) or zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyls ( 3 ). Recrystallization from a mixture of CH₂Cl₂ and methanol can lead to the formation of methanol adducts. The methanol ligands can either bind as Lewis base to the central zinc atom or as Lewis acid via a weak O–H ··· O hydrogen bridge to a phenoxide moiety. Methanol‐free complexes precipitate as dimers with central Zn₂O₂ rings.     

A novel cadmium(II) coordination polymer with biphenyl‐3,3′,4,4′‐tetra­carboxylic acid and 4,4′‐bipyridine

A novel cadmium(II) coordination polymer, poly[[[bis­(4,4′‐bipyridine)cadmium(II)]‐μ₃‐4,4′‐dicarboxy­biphenyl‐3,3′‐di­carboxyl­ato] 0.35‐hydrate], {[Cd(C₁₆H₈O₈)(C₁₀H₈N₂)₂]·0.35H₂O}_n, was obtained by reaction of Cd(CH₃COO)₂·3H₂O, 4,4′‐bipyridine (4,4′‐bpy) and biphenyl‐3,3′,4,4′‐tetra­car­boxylic acid (H₄L) under hydro­thermal conditions. Each Cd^II atom lies at the centre of a distorted octa­hedron, coordinated by four O atoms from three H₂L²⁻ ligands and N atoms from two monodentate 4,4′‐bpy ligands. Each H₂L²⁻ ligand coordinates to three Cd^II atoms through two carboxyl­ate groups, one acting as a bridging bidentate ligand and the other in a chelating bidentate fashion. Two Cd atoms, two H₂L²⁻ anions and four 4,4′‐bpy ligands form a ring dimer node, which links into an extended broad zonal one‐dimensional chain along the c axis.     

meso‐2,2′‐Di­phenyl‐3,3′,4,4′‐tetra­hydro‐2,2′‐bi­furan‐5,5′(2H,2′H)‐dione

The crystal structure of the title compound, C₂₀H₁₈O₄, contains a crystallographic inversion center. The C—C bond linking the two halves of the mol­ecule is slightly elongated at 1.577 (3) Å.     

Synthesis of Some Novel Phenyl Substituted Oxothiazolidin- 1’’,3’’,4’’-thiadiazolo-[3’,4’-b]thiazoline of 3β-Substituted Cholestane

Three title compounds 4a—4c have been synthesized by the cyclodehydration of 1’-benzylidine-4’-(3β-substituted-5α-cholestane-6-yl)thiosemicarbazones 2a—2c with thioglycolic acid followed by the treatment with cold conc. H2SO4 in dioxane. The compounds 2a—2c were prepared by condensation of 3β-substituted-5α-cholestan- 6-one-thiosemicarbazones 1a—1c with benzaldehyde. These thiosemicarbazones 1a—1c were obtained by the reaction of corresponding 3β-substituted-5α-cholestan-6-ones with thiosemicarbazide in the presence of few drops of conc. HCl in methanol. The structures of the products have been established on the basis of their elemental, analytical and spectral data.     

Energetic 4,4′‐Oxybis[3,3′‐(1‐hydroxytetrazolyl)]furazan and Its Salts

Energetic compounds that incorporate multiple nitrogen‐rich heterocycles are of great interest for high‐density energetic materials. A facile synthetic strategy to combine an oxy bridge and furazan groups, as well as tetrazole‐ols, into a molecule ( 5 ) was found. Some energetic salts based on 5 were prepared by neutralization. All of the compounds were fully characterized. Additionally, the structure of 7 has been elucidated by single‐crystal XRD analysis. Physicochemical and energetic properties were also studied; these show that these newly designed energetic salts exhibit good thermal stabilities. Hydroxylammonium salt ( 6 ) has a detonation performance and sensitivities comparable with those of 1,3,5‐trinitroperhydro‐1,3,5‐triazine (RDX).     

Biselenienyl series. II. Synthesis and resolution of 2,2′-dinitro-3,3′-biselenienyl-4,4′-dicarboxylic acid

2,2′-Dinitro-3,3′-biselenienyl-4,4′-dicarboxylic acid (VI), the first recorded compound of the 3,3′-biselenienyl series, has been prepared and resolved into its optical antipodes by fractional crystallization of its brucine salt. On the basis of the quasi-racemate method of Fredga and the O.R.D. spectra, to the dextrorotatory acid is assigned the R configuration.     

Energetic Materials Based on 5,5′‐Diamino‐4,4′‐dinitramino‐3,3′‐bi‐1,2,4‐triazole

A simple and straightforward synthesis of 5,5′‐diamino‐4,4′‐dinitramino‐3,3′‐bi‐1,2,4‐triazole by the selective nitration of 4,4′,5,5′‐tetraamino‐3,3′‐bi‐1,2,4‐triazole is presented. The interaction of the amino and nitramino groups improves the energetic properties of this functionalized bitriazole. For a deeper investigation of these properties, various nitrogen‐rich derivatives were synthesized. The new compounds were investigated and characterized by spectroscopy (¹H and ¹³C NMR, IR, Raman), elemental analysis, mass spectrometry, differential thermal analysis (DTA), X‐ray analysis, and impact and friction sensitivities (IS, FS). X‐ray analyses were performed and deliver insight into structural characteristics with which the stability of the compounds can be explained. The standard enthalpies of formation were calculated for all compounds at the CBS‐4M level of theory, revealing highly positive heats of formation. The energetic performance of the new molecules was predicted with the EXPLO5 V6.02 computer. A small‐scale shock reactivity test (SSRT) and a toxicity test gave a first impression of the performance and toxicity of selective compounds.     

Metal Salts of 3,3′‐Diamino‐4,4′‐dinitramino‐5,5′‐bi‐1,2,4‐triazole in Pyrotechnic Compositions

The synthesis of alkali and alkaline earth salts of 3,3′‐diamino‐4,4′‐dinitramino‐5,5′‐bi‐1,2,4‐triazole (H₂ANAT) is reported. The fast and convenient three steps reaction toward the target compounds does not require any organic solvents. In addition to an intensive characterization of all synthesized metal salts, the focus was on developing chlorine and nitrate‐free red‐light‐generating pyrotechnical formulations. Strontium 3,3′‐diamino‐4,4′‐dinitramino‐5,5′‐bitriazolate hexahydrate served as colorant and oxidizer in one molecule. The energetic properties of all developed pyrotechnical formulations assure safe handling and manufacturing.     

Synthesis of 3,3′ -methylenediisoxazoles

The synthesis of new 3,3′-methylenediisoxazoles (III), from 1,3-dichloromalondioxime (IX) and acetylenic compounds is reported. We have studied the transformation of the chloronitroso compound (VII), obtained from malondioxime (V) in ether with gaseous chlorine at ?70°, into IX. It was found that this was possible only by heating a DIYISO solution. The characteristics of the compounds which are described are reported.