Convenient Preparation of N,N′‐Diphenyl‐N,N′‐bis(4‐aminophenyl)‐p‐phenylenediamine

Abstract

This article describes modified conditions to prepare N,N′‐diphenyl‐N,N′‐bis(4‐aminophenyl)‐P‐phenylenediamine in 60% overall yield.     

Synthesis and Crystallographic Study of1,6‐bis‐(N‐phenothiazinyl)‐2,4‐hexadiyne

1,6‐bis‐(N‐phenothiazinyl)‐2,4‐hexadiyne (I) was synthesized in high yield by oxidative coupling of N‐propargyl phenothiazine. Grown from methylene chloride‐hexane solution, I is a monoclinic crystal, space group C2/c a=14.9500(18) Å; b=13.5512(15) Å; c=12.0116(10) Å; β=102.628(9)° Å; V=2374.6(4) ų. The intermolecular distances and arrangement of I in the unit cell preclude the usual diacetylene reactivity. Nevertheless, heating of I at 145°C results in decomposition of I to phenothiazine and a dark brown solid. In addition, cation‐radicals of I were prepared by oxidation with nitrosonium tetrafluoroborate and iodine to give stable ion‐radical salts.     

One Facile Preparation of N‐Aroyl‐N′‐arylsulfonylhydrazines by Oxidation of Aromatic Aldehyde N‐Arylsulfonylhydrazones with bis(Trifluoroacetoxy)iodobenzene

N‐aroyl‐N′‐arylsulfonylhydrazines can be obtained by oxidation of aromatic aldehyde N‐arylsulfonylhydrazones with bis(trifluoroacetoxy)iodobenzene in acetone at room temperature in mild to good yields.     

Application of Sulfinyl bis(2,4‐dihydroxythiobenzoyl) in the Synthesis of N‐Substituted 2‐Amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles

One‐stage synthesis of N‐substituted 2‐amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles is described. The compounds were prepared by the reaction of the sulfinyl bis(2,4‐dihydroxythiobenzoyl) (STB) with 4‐substituted 3‐thiosemicarbazides. STB was obtained from 2,4‐dihydroxybenzenecarbodithioic acid and thionyl dichloride. The structure of compounds was confirmed by IR, ¹H NMR, ¹³C NMR, and EI‐MS data.     

Oxidative Cyclization of Aromatic Aldehyde N‐Acylhydrazones by bis(Trifluoroacetoxy)iodobenzene

Aromatic aldehyde N‐acylhydrazones were oxidized into 2,5‐disubstituted 1,3,4‐oxadiazoles with bis(trifluoroacetoxy)iodobenzene in CHCl₃ or DMSO at room temperature in good to excellent yields.     

Electroanalytical performance of Cd(II) selective sensor based on PVC membranes of 5,5′‐(5,5′‐(benzo[c][1,2,5]thiadiazole‐4,7‐diyl)bis(thiophene‐5,2‐diyl))bis(N1,N1,N3,N3‐tetraphenylbenzene‐1,3‐diamine)

The construction and performance characteristics of polymeric membrane electrodes based on neutral ionophore 5,5′‐(5,5′‐(benzo[c][1,2,5]thiadiazole‐4,7‐diyl)bis(thiophene‐5,2‐diyl))bis‐(N1,N1,N3,N3‐tetraphenylbenzene‐1,3‐diamine) (L) for quantification of cadmium ions, are described. Effect of plastisizers dibutylpthalate (DBP), tri‐n‐butylphosphate (TBP), dioctylpthalate (DOP), o‐nitrophenyloctyl ether (o‐NPOE), 1‐chloronaphthalene (CN) and ionic additives sodium tetraphenylborate (NaTPB), potassium tetrakis p‐(chlorophenyl)borate (KTpClPB) was studied. Best performance was obtained with the membrane having a composition L?:?PVC?:?DBP?:?NaTPB?≡?2?:?37?:?59?:?2 (w/w; mg). The membrane electrode exhibits Nernstian response in the concentration range 6.3?×?10^?8 to 1.0?×?10?^?1?mol?L^?1 with detection limit 3.6?×?10^?8?mol?L^?1 and is not affected by H⁺ ions over a wide pH range 3.0–10.0. The electrode possess a fast response time of 10?s and shelf life period of 3 months. The analytical utility of the proposed electrode has demonstrated by its application in the determination of cadmium in water, medicinal plants and soil samples. It could also be used successfully as an indicator electrode in the potentiometric titration of Cd²⁺ with EDTA (ethylenediaminetetraacetic acid).     

Dye Binding Characteristics of N,N′‐Methylene‐bis‐acrylamide (NNMBA)‐Crosslinked Polyacrylamide‐Supported Amine and its Photooxidizing Ability

The dye binding characteristics of 8 mol% NNMBA‐crosslinked polyacrylamide‐supported amine is investigated with Rose Bengal (RB), Methyl Orange (MO), Methylene Blue (MB) and Methyl Red (MR). The influence of the concentration of dye solution on dye binding, time course of dye binding and characterization were explored. It is observed that binding is higher in the case of Rose Bengal and dye binding depends on the polarity, as well as the size of the dye molecule. The photooxidation property of polymer bound RB was investigated towards the oxidation of benzoin to benzil. RB bound polymer acts as an efficient heterogenous photooxidizing agent.     

Efficient Synthesis of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines

A general method for the preparation of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines is described. These heterocycles can be synthesized from their respective anilines with 2‐chloro‐2‐imidazoline or 2‐chloro‐1,4,5,6‐tetrahydropyrimidine, generated in situ from imidazolidin‐2‐one and tetrahydropyrimidin‐2(1H)‐one activated by dimethyl chlorophosphate, in good to excellent yields.     

Efficient Synthesis of N‐Oxide Derivatives: Substituted 2‐(2‐(Pyridyl‐N‐oxide)methylsulphinyl)benzimidazoles

Different substituted 2‐chloromethylpyridyl derivatives (6a–d) were oxidized with mCPBA to give the respective 2‐chloromethylpyridine‐N‐oxide derivatives (7a–d) at low temperature, which on condensation with 2‐mercapto‐1H‐benzimidazole (8a–c) in the presence of aprotic solvents give the 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfanyl]‐1H‐benzimidazole (9a–d) in good yield. Finally, 9a–d oxidized with mCPBA in chlorinated solvent gives a mixture of 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfonyl]‐1H‐benzimidazole (3a–d, 10%) and 2‐[[(pyridin‐2‐yl‐1‐oxide) methyl]sulfinyl]‐1H‐benzimidazole (4a–d, 90%) derivatives.     

Raman study of a liquid crystalline gel consisting of photochromic 4‐methyl‐N‐(4‐n‐heptyloxysalicylidene)aniline and a gelling agent (R,R′)‐1,2‐bis(dodecanoylamino)cyclohexane

A liquid crystalline physical gel has been prepared from the mixture of a nematic liquid crystal and a low molecular mass gelling agent containing a hydrogen‐bonding moiety. The newly synthesized liquid crystalline compound exhibited photochromism in the crystalline solid phase. Although photochromism was not observed in the nematic gel state of the mixture, the lifetime of photochromism in the solid phase became longer, compared with that of a single liquid crystalline compound. Some Raman bands of the mixture showed a marked change in both intensity and frequency through the phase transitions. These bands have been assigned to the vibrational modes related to the core part of molecule.     

Smectogenic properties of N,N′‐bis[(2‐hydroxy‐4‐alkoxyphenyl)methylene]benzene‐1,4‐diamine liquid crystals with double lateral H‐bonds

A series of eight liquid crystalline compounds, N,N′‐bis[(2‐hydroxy‐4‐alkoxyphenyl)methylene]benzene‐1,4‐diamines, has been synthesized and characterized. These homologous compounds differ in the length of terminal alkyl group C _n H_2n+1 wherein n is an even number ranging from 4 to 18. The spectroscopic techniques, FTIR, ¹H NMR and ¹³C NMR, were employed to characterize the molecular structure. The transition temperatures of all the title compounds and their mesophases were studied by differential scanning calorimetry and polarizing microscopy. All the compounds were smectogenic, exhibiting both tilted and non‐tilted molecular orientation in their smectic phases. Further investigation to ascertain the anisotropic nature of subphases within the smectogenic region was carried out using X‐ray diffraction.     

Synthesis of 1,4‐Diaryl‐piperazine‐2,5‐diones: New Behavior of N,N‐Dimethylformamide Dimethyl Acetal (DMFDMA)

Reactions of chloroacetamides (5) with N,N‐dimethylformamide dimethyl acetal gave 1,4‐diaryl‐piperazine‐2,5‐diones 11a–e in good yield, rather than 1,5‐diaryl‐3,7‐dimethoxy‐1H,5H‐[1,5]diazocine‐2,6‐diones (9a–e).     

The single-crystal electron spin resonance spectra of bis chloro bis(N,N′-substituted urea)oxovanadium(IV) compounds diluted in the corresponding tris-chloro bis(N,N′-substituted)urea indium(III) compounds

Single crystal ESR spectra of VOCl₂L₂ (where L = N, N, N′, N′-tetramethyl urea (tmu), N, N′-dimethylethyleneurea, N, N′-dimethylpropyleneurea, tris(dimethylamino)phosphincoxide) diluted in the corresponding Inøcl₃L₂, at Q-band frequencies are reported. The ESR data are consitent with C₂ point symmetry for VOCl₂(tmu)₂ whilst the other compounds approximate very closely to this point symmetry. A rotation of the g and A tensor axes in the plane perpendicular to the terminal VO vector fall in the range 8–15° for the four compounds studied. The spin Hamiltonian parameters for VOCl₂(tmu)₂, in conjunction with the published polarized electronic absorption spectra, have been analysed via angular overlap calculations. For VOCl₂(tmu)₂ unusual ligand hyperfine splittings were observed. These were analysed by spectrum simulation in terms of two equivalent chlorine atoms where the chlorine hyperfine and nuclear quadrupole tensors are of comparable magnitude.     

Synthesis and Characterization of Novel Poly(Arylene Ether)s from 1,3‐bis(4‐Hydroxyphenyl) Benzene

Abstract

Several poly(aryl ether)s have been prepared by the condensation of 1,3‐bis(4‐hydroxy phenyl) benzene with different trifluoromethyl activated bis‐fluoro compounds. IR, ¹H and ¹³C NMR, and elemental analyses have established the resulting polymer structures. The properties of the polymers have been evaluated by DSC, TGA, dynamic mechanical analysis (DMA) and stress–strain analysis. The polymers 1a and 1c showed semi‐crystalline behavior as evident by sharp crystalline melting peaks at 299°C and 330°C along with glass transitions at 202°C and 216°C, respectively. The polymers showed very good thermal stability in air, high modulus, and high tensile strength with low elongation at break.     

Synthesis of New N‐(5‐Oxo‐2,5‐dihydro)pyrrol‐3‐yl Glycines and N‐(5‐Oxo‐2,5‐dihydro)pyrrol‐3‐yl Glycines Esters

Following our efforts towards the synthesis of new potential inhibitors of Xanthine Dehydrogenase (XDH), we describe here a general method for the preparation of N-(5-oxo-2,5-dihydro)pyrrol-3-yl glycines and N-(5-oxo-2,5-dihydro)pyrrol-3-yl glycine esters from glycine ethyl ester hydrochloride and various 4-hydroxy-5-oxo-2,5-dihydro-1H-pyrrole-3-carboxylic acid esters and carbonitriles.     

Improved Synthesis of C 2‐Symmetric 4,4′‐α,ω‐Alkylenedioxy‐bis(3‐methoxybenzaldehydes)

Abstract

An improved Williamson synthesis of C ₂‐symmetric 4,4′‐(α,ω‐alkylenedioxy)‐bis(3‐methoxybenzaldehydes) from vanillin is described. These dialdehydes are often insoluble in cold acetone, which renders their purification especially facile.     

Synthesis,characterization and nucleolytic property of bis(N,N′-dimethylglycinato)copper(II)

Aquabis(N,N-dimethylglycinato)copper(II) dihydrate, [Cu(dmg)₂(H₂O)]·2H₂O, has been synthesized and characterized by elemental analysis, FT-IR, magnetic data, thermal analysis, solution UV-visible spectroscopy, X-ray crystal structure analysis and electrospray ionization mass spectroscopy. The square pyramidal copper(II) complex crystallizes in the orthorhombic space group P2₁2₁2₁. The complex cleaves circular plasmid DNA (pBR322) in the presence of H₂O₂. The extent of cleavage varies with the concentration range of the complex, the type of buffer used, pH of buffer and the concentration of H₂O₂. Hydroxyl radical scavenger can inhibit the nucleolytic ability of this complex.     

Preparation and Characterization of Poly(N‐Vinylpyrrolidone‐co‐Methacrylic Acid) Hydrogels

In this study, N‐vinylpyrrolidone (VP)/methacrylic acid (MAA) copolymers have been prepared at three different mole percents, the methacrylic acid composition being around 5, 10, 15%. MAA and VP monomer mixtures have been irradiated in ⁶⁰Co‐γ source at different irradiation doses and percent conversions have been determined gravimetrically. ～80% conversion of monomers into hydrogels were performed at 3.4 kGy irradiation dose. These hydrogels were swollen in distilled water at pH 4.0, 7.0, and 9.0. P(VP/MAA) hydrogel which contains 5% methacrylic acid showed the maximum % swelling at pH 9.0 in water. Diffusion of water was found to be of non‐Fickian character. Diffusion coefficients of water in P(VP/MAA) hydrogels were calculated. Initial swelling rates of P(VP/MAA) hydrogels increased with increasing pH and MAA content in hydrogels. Swelling kinetics of P(VP/MAA) hydrogels was found to be of second order. Thermal behavior of PMAA, PVP and P(VP/MAA) hydrogel were investigated by thermal analysis. P(VP/MAA) hydrogel gained new thermal properties and the temperature for maximum weight loss and temperature for half‐life of P(VP/MAA) hydrogel were determined.     

Amino Acids as a Chiral Pool: Synthesis of (S)‐and (R)‐2‐N‐Carbomethoxy‐5‐aminoindane from (S)‐ and (R)‐Phenylalanines

Enantioselective syntheses of (R)‐and (S)‐2‐N‐carbomethoxy‐5‐aminoindanes from (R)‐ and (S)‐phenylalanines, respectively, are described. A Friedel–Crafts reaction employing N‐carbomethoxy phenylalanine leads to chiral 2‐N‐carbomethoxy‐1‐indanone, which is diastereoselectively reduced to 1‐hydroxy‐2‐N‐carbomethoxyindane. After protection of the hydroxyl group, a regioselective nitration gives a 6‐nitroindane intermediate, which upon hydrogenation affords (R)‐or (S)‐2‐N‐carbomethoxy‐5‐aminoindane.     

Mechanism for Base Hydrolysis of Poly(N‐vinylformamide)

The industrial production of poly(N‐vinylformamide), PNVF, was started a few years ago, making the desired polyvinylamine, PVAm, accessible on a large scale via hydrolysis of PNVF. According to the literature, the key to achieving a 100% conversion of PNVF into PVAm is to employ basic hydrolysis conditions. However, results disclosed in the present note contradict such statements. A radically obtained PNVF polymer, assigned further on as PNVF‐000 with M¯_w=2.63×10⁵ g/mol, was submitted to a stepwise hydrolysis in aq. NaOH solution with periods lasting 0, 5 20, 40, 90, 175, and 240 min. Aliquots ware taken, neutralized, precipitated and purified. For each polymer thus obtained the ¹³C NMR spectra was recorded, providing evidence for transient formation of amidine rings. These rings while decomposing leave not only primary amine functions attached to the backbone, but also OH groups. Elementary analysis of PNVF‐240, the polymer fully deprived of formaldehyde groups, confirm these findings. From the C/N=3.17 ratio the share of vinyl‐alcohol units present in the chains is estimated to be 42 mol%. Considering all the experimental results, the mechanism of basic hydrolysis was established.