Electrogenerated chemiluminescence in mechanistic investigations of electroorganic reactions: Part I. Cathodic cleavage of bis-(2,4,5-triphenylimidazolyl)-1,2′ (dilophyl)

In the simultaneous cathodic reduction of bis-(2,4,5-triphenylimidazolyl)1,2′ L₂ and some aromatic hydrocarbons A in dimethylformamide the emission of A is observed. This electrogenerated chemiluminescence (ECL) originates from the electron transfer between A^?. and the imidazolyl radicals L^., which are formed by a cleavage of L₂^?. into L^. and the imidazolyl anion L_.^? By detecting L₂^?. and L^. as intermediates, this ECL study provides evidence for an ECE mechanism of the cathodic cleavage of L₂.     

Spacer-verbrückte Bis-, Tris- und Tetrakis(ferrocenyl)-1,3-Diketone

Hydrocarbon-bridged Metal Complexes. XLVII. Bis-, Tris- und Tetrakis(ferrocenyl)-1,3-Diketones Claisen condensation of the enolate from acetylferrocene with diethyloxalate, 1,8-octanedicarboxylic dimethyl ester, fumaroyl dichloride, the chlorides of terephthalic acid and of 1,3,5-benzenetricarboxylic acid, tetramethyl-1,2,4,5-benzene tetracarboxylate and with 3,6-di-t-butyl-9,9′-dimethyl-xanthene-1,8-dicarboxylic dimethyl ester gives the corresponding bis-, tris- and tetrakis(ferrocenyl)-1,3-diketones 2 – 8 . Their oxidation potentials were measured by cyclovoltammetry. Diferrocenoyl methane exists in the crystal as the keto-enol tautomer.     

Poly(2,2′-(1,4-phenylenedivinylene) Bis-8-hydroxyquinaldine) Modified Glassy Carbon Electrode for the Simultaneous Determination of Paracetamol and p-Aminophenol

A novel assay is reported for the simultaneous determination of paracetamol and p-aminophenol using a poly(2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinaldine) modified glassy carbon electrode. Poly(2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinoline) modified electrodes were prepared by electrochemical polymerization. The electrode surface was characterized by scanning electron microscopy. The electrochemical behavior of the modified electrode was investigated by cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The anodic peak potentials for paracetamol and p-aminophenol were at 580 and 337 millivolts, respectively, with a separation of 243 millivolts, adequate for their simultaneous determination. The results showed that the linear dynamic ranges for paracetamol and p-aminophenol were 0.5–200 micromolar and 3–150 micromolars, whereas the limits of detection were 0.075 and 0.45 micromolar, respectively. The novel poly(2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinaldine) modified electrode provided excellent selectivity, sensitivity, and stability and was employed for the determination of paracetamol and p-aminophenol in pharmaceutical products and urine.     

A peroxide-bridged imidazole dimer formed from a photochromic naphthalene-bridged imidazole dimer

2,4,5-Triphenylimidazole (lophine) is known as the first chemiluminescence substrate, and its oxidized derivative, the 2,4,5-triphenylimidazolyl radical, corresponds to the coloured species in the photochromic reaction of hexaarylbiimidazole (HABI). We report the first direct observation of the O(2) adduct of the imidazolyl radical that forms the end-on peroxide-bridged imidazole dimer. The ring-opening reaction of the peroxide-bridged imidazole dimer leading to the formation of an N-benzoylbenzamidine derivative supports the presence of the 4,5-epidioxide of lophine as a reaction intermediate of its chemiluminescence.     

Bis(trimethylsilyl)amino-halogenoborane und ihre cyclischen Kondensationsprodukte

Zusammenfassung Bis-[bis(trimethylsilyl)amino]-fluorboran (I), Bis-(trimethylsilyl)-amino-dichlorboran (II) und Bis-[bis(trimethylsilyl)-amino]-chlor-boran (III) werden durch Umsetzung von BCl₃ und BF₃ mit NaN(Sime ₃)₂ in Äther dargestellt. Alle Verbindungen lassen sich thermisch unter Abspaltung von Trimethylhalogenosilanen kondensieren. Während II zu B-Trichloro-N-tris(trimethylsilyl)-borazol kondensiert, ergeben I und III überraschend ein viergliedriges B–N-Ringsystem.Phenyl-alkoxy-bis(trimethylsilyl)aminoborane gehen ähnliche Kondensationsreaktionen ein.

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Bis-[bis(trimethylsilyl)amino]-fluoroborane (I), bis(trimethylsilyl)amino-dichloroborane (II) and bis-[bis-(trimethylsilyl)amino-]chloroborane (III) were synthesized by reaction of BF₃ and BCl₃ with sodium-bis(trimethylsilyl)-amide. All compounds undergo thermal condensation under elimination of the corresponding trimethylhalosilane. So II forms B-trichloro-N-tris(trimethylsilyl)-borazene, while I and III unexpectedly yield a fourmembered B–N-ring system. Phenyl-alkoxy-bis-(trimethylsilyl)-aminoboranes condense in a similar way to B-phenyl-N-trimethylsilyl-borazene.

     

Über heteroorganische Verbindungen, 39. Mitt.: Neue Darstellungsmethoden für Bis-(dialkylthiophosphinyl)-trisulfide. Reaktionsmechanismus

Zusammenfassung Dialkyl-dithiophosphinsäuren reagieren mit Morpholinoschwefelchlorid zu Bis-(dialkyl-thiophosphinyl)-trisulfiden. In Anwesenheit von Triäthylamin bilden sich die bisher unbekannten S-Morpholino-dialkyl-mercapto-dithiophosphinate, die, dem angenommenen Reaktionsmechanismus entsprechend, mit Chlorwasserstoff und Dithiophosphinsäuren die Bis-(dialkyl-thiophosphinyl)-trisulfide liefern. S-Morpholino-diäthyl-mercapto-dithiophosphinat und Diäthyldithiophosphinsäure setzen sich zu Bis-(diäthyl-thiophosphinyl)-trisulfid um.

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Heteroorganic compounds, XXXIX.: New methods for the preparation of bis-(dialkylthiophosphinyl)-trisulfides, and a reaction mechanism

Dialkyldithiophosphinic acids react with morpholinosulfenyl chloride to give bis-(dialkylthiophosphinyl)-trisulfides. In the presence of triethylamine the hitherto not described S-morpholino-dialkyl-mercapto-dithiophosphinates are formed. According to an assumed reaction mechanism the latter react with HCl and dithiophosphinic acids to give bis-(dialkyl-thiophosphinyl)-trisulfides. S-Morpholino-diethylmercapto-dithiophosphinate and diethyldithiophosphinic acid yield bis-(diethylthiophosphinyl)-trisulfide.

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38. Mitt.:L. Almasi undA. Hantz, Mh. Chem.100, 798 (1969).     

Electrochemical behavior of nickel bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 dibromide in an aprotic solvent

The electrochemical behavior of bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 and its nickel dibromide complex on dropping mercury and glassy carbon electrodes in an aprotic solvent was studied by AC polarography and cyclic voltammetry. Both the ligand and the nickel ion complex were shown to undergo electroreduction. The electrochemical reduction of nickel bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 dibromide occurred stepwise and formed intermediate nickel(I) species.     

3-Diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolat(II) — Synthese und Struktur

3-Diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolate(II) — Synthesis and Structure Bis-(N′, N′-diethyl-N-benzoylselenoureato)nickel(II) reacts with diphosgene in benzene to 3-diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolate(II). Its structure is confirmed by RKSA and ESCA. The compound consists of cations, which are planar fivemembered rings and of tetrahedral tetrachloroniccolate(II) anions. The complex is isomorphic with 3-diethylamino-5-phenyl-1,2,4-dithiazolium-tetrachloroniccolate(II).     

Pinacol-Pinacolone Rearrangement of 1, 2-Di-(p-methoxyphenyl)-ethane-1, 2-diol and Bis-(4-methoxyphenyl)-acetaldehyde in Acid Media

1, 2-Di-(p-methoxyphenyl)-ethane-1, 2-diol gave in acid media bis-(4-methoxy-phenyl)-acetaldehyde, 4-4′-dimethoxy-deoxybenzoin, and 1, 2-di-(p-methoxyphenyl)-ethylene oxide; their respective yields being influenced by at least 3 factors: (i) the acid, (ii) its concentration, and (iii) the reaction period. Bis-(4-methoxyphenyl)-acetaldehyde rearranged to the deoxybenzoin in boiling sulfuric (50%) or phosphoric (75%) acids (w/w), and to two isomeric 1, 2-diacetoxy-1, 2-di-(p-methoxyphenyl) ethanes when it was heated with acetic anhydride. The mechanisms of these reactions are discussed.     

Activation parameters for the recombination reaction of intramolecular radical pairs generated from the radical diffusion-inhibited HABI derivative

Activation parameters were determined for the recombination of radical pairs arising from newly designed, photochromic, radical diffusion-restricted hexaarylbiimidazole (HABI) derivative. We have developed a new type of radical diffusion-inhibited HABI derivative, which contains two equivalent HABI units and yields a tetraradical with four equivalent 2,4,5-triphenylimidazolyl radical (TPIR) units by photoirradiation. This radical dimerization proceeds by a successive first-order reaction from the tetraradical to the parent molecule via a diradical. The rate constants of each reaction were determined from the decay profile of EPR signal intensities. The entropies of activation (DeltaS(double dagger)) for the first and the successive dimerization steps were estimated to be -178.5 and -205.5 J K(-1) mol(-1), respectively. Within the experimental temperature range, the radical dimerizations are entropy-controlled (-TDeltaS(double dagger) > DeltaH(double dagger)). The large negative DeltaS(double dagger) values imply a highly ordered transition state, indicating that the radical dimerizations occur when the TPIR units interact at a specific orientation. The present study demonstrates the availability of radical diffusion-inhibited HABI for the kinetic study of radical-radical reaction.     

Selectivities in the reaction of vicinal diimines and acyl chlorides

The reaction of vicinal diimines and acyl chlorides in the presence of triethylamine produces 3-imino-β-lactams and/or bis-β-lactams chemo-, regio-, and stereoselectively, which are important intermediates in pharmaceutical and organic synthesis. The selectivities in the reaction have been investigated. The results indicate that all diimines react with various ketenes generated from acyl chlorides in the presence of triethylamine to give rise to cis-4-imino-β-lactams (mono-cis-β-lactams) diastereoselectively due to the electron-withdrawing property of the imino group in the vicinal diimines. Bis-β-lactams were obtained from diimines via the mono-cis-β-lactams as intermediates. Only ketenes with strong electron-donating substituents can react with the mono-cis-β-lactams to yield bis-β-lactams, affording a pair of C2-symmetric cis-bis-β-lactams with symmetric diimines, two or four pairs of diastereomeric bis-β-lactams with ketoaldehyde-derived unsymmetric diimines depending on the steric hindrance of their N-substituents. The current investigation provides very important information for the selective preparation of mono- and bis-β-lactams from vicinal diimines.     

A novel synthesis of bis-(α-hydroxyalkyl)phosphinic acids involving microwave irradiation

A simple, efficient, and general method has been developed for the synthesis of bis-(α-hydroxyalkyl)phosphinic acids from hypophosphorous acid using microwave irradiation. Bis-(α-hydroxyalkyl)phosphinic acids were obtained in high yield under mild conditions by reaction of hypophosphorous acid with aldehydes under microwave irradiation.     

Phenylated polyimides: Diels-Alder reaction of biscyclopentadienones with dimaleimides

A series of phenylated polydihydrophthalimides has been synthesized by the Diels-Alder reactions of 3,3′-(oxydi-p-phenylene)bis(2,4,5-triphenylcyclopentadienone) and 3,3′-(p-phenylene)bis(2,4,5-triphenylcyclopentadienone) with N,N′-o-, -m-, and -p-phenylenedimaleimide. The polydihydrophthalimides were soluble in dimethylformamide (DMF) and had intrinsic viscosities that ranged from 0.33 to 1.01, the polymers were dehydrogenated thermally and chemically to afford the corresponding phenylated polyphthalimides. The totally aromatic polyimides were also soluble in DMF but had intrinsic viscosities only as high as 0.41. The thermogravimetric analyses of the polyphthalimides showed breaks near 530°C in air and in nitrogen atmospheres.     

Synthesis and reactions of pyrazole-4-carbaldehydes

1-, 3-, and 5-Alkylpyrazoles, as well as linearly bridged bis-pyrazoles, were converted into the corresponding 4-formyl derivatives by Vilsmeier-Haak reaction both under standard conditions and under microwave activation in DMF over a period of 10 min. 1,1′-(Hexane-1,6-diyl)bis(3,5-dimethyl-1H-pyrazole) and 1,1′-(benzene-1,4-diyldimethylene)bis(3,5-dimethyl-1H-pyrazole) gave rise to 4-formyl derivatives at both pyrazole rings. 5-Chloro-1,3-dialkyl-1H-pyrazoles failed to undergo formylation according to Vilsmeier-Haak or under microwave activation. 1,1′-Bridged bis-3,5-dimethyl-1H-pyrazoles reacted with 2-sulfanylethanol on heating in the presence of chloro(trimethyl)silane to give the corresponding bridged bis-4-(1,4,6-oxadithiocan-5-yl)-1H-pyrazoles.     

Bis-(p-nitrophenylethyl)phosphoromonochloridate,a new versatile phosphorylating agent

A new phosphorylating agent, bis-(p-nitrophenylethyl)phoshoromonochloridate, has been prepared and is used for 3′- and/or 5′-phosphorylations of nucleosides. The resulting bis-(p-nitrophenylethyl)phosphotriesters are versatile synthons in oligonucleotide syntheses leading finally to 3′- and/or 5′-terminated oligonucleotides in excellent yields.     

Diorgano-tellur-bis-(dialkylcarbamate) und -(dithiocarbamate)

Diorganyltellurium Bis-(dialkylcarbamates) and -(dithiocarbamates) Compounds of the type R₂Te(X₂CNR′₂)₂, with R ? C₆H₅, CH₃; R′ ? CH₃, C₂H₅, i-C₃H₇, c-C₆H₁₁, C₆H₅, and X ? S, are obtained by reaction of dimethyltellurium with tetraorganyl-thiuram-disulfides. Dimethyltellurium diiodide or diphenyltellurium dichloride react with sodium dithiocarbamates or with in situ prepared ammonium dithiocarbamates. Some compounds can be synthesized by reaction of diphenyltellurium oxide with amine in solutions of carbon disulfide. The synthesis of diphenyltellurium- and dimethyltellurium bis-(dimethylcarbamates) results from the interaction of diorganyltellurium diethanolate with dimethylammonium dimethylcarbamate. Decomposition reactions of the compounds in solid and solution are studied ¹H-NMR, ¹³C-NMR, and mass spectroscopically. Diorganyltellurium diethylen-bis-(N,N′-dimethyldithiocarbamates) are obtained by reaction of dimethyltellurium diiodide or diphenyltellurium dichloride and sodium ethylen-bis-(N,N′-dimethyldithiocarbamate) as polymeric products.     

Radical anions of flavonoids

Several representatives of natural flavonoids and their synthetic nitro‐derivatives have been investigated by polarography and electron paramagnetic resonance (EPR) spectroscopy under electrochemical reduction in acetonitrile, dimethylformamide (DMF), dimethylsulfoxide (DMSO) or 1,2‐dimethoxyethane. All the compounds studied are reduced in the first stage by one‐electron transfer, apart from flavanone, which accepts two electrons simultaneously. However, the primary radical anions were detected by EPR spectroscopy only for 4′‐nitroflavone. It was shown that radical anions of other flavonoids quickly dimerized. The analysis of the temperature dependence of the hyperfine interaction constants and broadening of lines in EPR spectra of 4′‐nitroflavone radical anions has shown that the distribution of spin density is due to both the change of polarity of the medium and rotation of the nitrophenyl moiety. The assignment of hyperfine structure constants for the 4′‐nitroflavone radical anion was confirmed by density functional theory (DFT) calculations. Copyright © 2011 John Wiley & Sons, Ltd.     

Five-membered 2,3-dioxo heterocycles: XCI. Reaction of 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with dimedone. Crystalline and molecular structure of 3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-6,7-dihydrospiro[1-benzofuran-3,2′-pyrrole]-2,4,5′(1′H,5H)-trione

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with 5,5-dimethylcyclohexane-1,3-dione to give 3′-aroyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-6,7-dihydrospiro[1-benzofuran-3,2′-pyrrole]-2,4,5′(1′H,5H)-triones. The crystalline and molecular structures of 3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-6,7-dihydrospiro[1-benzofuran-3,2′-pyrrole]-2,4,5′(1′H,5H)-trione were determined by X-ray analysis.     

Synthesis and Characterization of Polyesterimides Containing Ether Linkages

Abstract

Three novel dicarboxylic acids, bis-4,4′-[N-4(4′-hydroxycarbonyl phenyleneoxy) phthalimido] diphenyl sulfone, bis-4,4′-[N-4(4′-hydroxycarbonyl phenyleneoxy) phthalimido] diphenyl methane, and bis-4,4′-[N-4(4′-hydroxycarbonyl phenyleneoxy) phthalimido] diphenyl ether, were synthesized, and several polyesterimides were prepared from diacid chlorides and bisphenols by solution polycondensation. The polymers were obtained in 65–88% yield and had inherent viscosities in the 0.18 to 0.64 dL/g range. The polymers were characterized by IR, elemental analysis, x-ray, TGA, DSC, and solubility tests. All the polymers were readily soluble in polar aprotic solvents and had a 10% weight loss temperature above 375°C in nitrogen.     

Five-membered 2,3-dioxo heterocycles: LX. Reaction of 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with cyclic enehydrazino ketones. Crystalline and molecular structure of N-[3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6, 6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]-3-nitrobenzamide

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with N′-(5,5-dimethyl-3-oxocyclohex-1-en-1-yl)benzohydrazides to give the corresponding N-[3′-aroyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]benzamides. The molecular and crystalline structure of one of the products, N-[3′-benzoyl-4′-hydroxy-1′-(2-hydroxyphenyl)-6,6-dimethyl-2,4,5′-trioxo-1′,4,5,5′,6,7-hexahydrospiro[indole-3,2′-pyrrol]-1(2H)-yl]-3-nitrobenzamide, was determined by X-ray analysis.