Silver‐catalyzed Glaser coupling of alkynes

Excellent yields were obtained from the silver nitrate‐catalyzed homocoupling reaction of alkynes in N,N‐dimethylformamide using triphenylphosphine as ligand. This safe and simple silver catalytic system has been employed in a safe and efficient protocol for the synthesis of various 1,3‐diyne products from the corresponding aromatic or aliphatic alkynes with good air stability and absence of side products. Copyright © 2015 John Wiley & Sons, Ltd.     

Electrophilic Reactivities of 1,2‐Diaza‐1,3‐dienes

The kinetics of the reactions of 1,2‐diaza‐1,3‐dienes 1 with acceptor‐substituted carbanions 2 have been studied at 20 °C. The reactions follow a second‐order rate law, and can be described by the linear free energy relationship log k(20 °C)=s(N+E) [Eq. (1)]. With Equation (1) and the known nucleophile‐specific parameters N and s for the carbanions, the electrophilicity parameters E of the 1,2‐diaza‐1,3‐dienes 1 were determined. With E parameters in the range of ?13.3 to ?15.4, the electrophilic reactivities of 1 a–d are comparable to those of benzylidenemalononitriles, 2‐benzylideneindan‐1,3‐diones, and benzylidenebarbituric acids. The experimental second‐order rate constants for the reactions of 1 a – d with amines 3 and triarylphosphines 4 agreed with those calculated from E, N, and s, indicating the applicability of the linear free energy relationship [Eq. (1)] for predicting potential nucleophilic reaction partners of 1,2‐diaza‐1,3‐dienes 1 . Enamines 5 react up to 10² to 10³ times faster with compounds 1 than predicted by Equation (1), indicating a change of mechanism, which becomes obvious in the reactions of 1 with enol ethers.     

Catalysis in competing isocyanate reactions. I. Effect of organotin–tertiary amine catalysts on phenyl isocyanate and N-butanol reaction

An analytical method based on high performance liquid chromatography (HPLC) has been developed to investigate the competing isocyanate reactions under the influence of various catalysts. The kinetics of the model reaction between phenyl isocyanate and n-butanol was studied in acetonitrile at 50°C. Effects of various catalysts such as an organotin compound, dibutyltin dilaurate, and tertiary amines, 1,4-diazabicyclo-(2,2,2)octane,N,N′,N″-pentamethyldiprophylene triamine,N,N′N″-tris(3-dimethyl-aminopropyl)-3-hexahydrotriazine, and N,N,N′-trimethylaminoethyl-ethanolamine on the reaction rate and the formation of reaction products were investigated. The reactions were followed by determining the NCO disappearance using the standard di-n-butylamine back-titration method as well as measuring the formation of various reaction products using the HPLC method. The relative specificity of a catalyst in isocyanate reactions can thus be determined from the profile of the model reaction which depends upon the structure of the catalyst employed.     

Catalysis in competing isocyanate reactions. II. Competing phenyl isocyanate reactions catalyzed with N,N′,N″-pentamethyldipropylenetriamine

The kinetics of the N,N′,N″-pentamethyl dipropylene triamine (PMPT)-catalyzed reaction of phenyl isocyanate with n-butanol was studied in acetonitrile between 26.5 and 50°C by measuring the NCO disappearance as well as the formation of the various reaction products by means of the standard dibutylamine back-titration method and the high-performance liquid chromatography (HPLC) method. The resulting products from the phenyl isocyanate and n-butanol reaction were found to be N-butyl phenylcarbamate, N-butyl-α,γ-diphenylallophanate, and triphenylisocyanurate. Trimer formed at the expense of carbamate formation even at a high OH/NCO ratio. Allophanate appeared to be an intermediate in the formation of trimer. PMPT was found to be a urethane and trimerization catalyst for the model reaction of phenyl isocyanate with n-butanol in acetonitrile. The PMPT-catalyzed reaction of phenyl isocyanate with n-butanol in the presence of water in acetonitrile at 50°C was also investigated. The resulting reaction products consisted of n-butyl phenylcarbamate, n-butyl-β,γ-diphenylallophanate, triphenylisocyanurate, sym-triphenylbiuret, and N,N′-diphenylurea. The presence of water retarded the disappearance of NCO groups as well as the trimer formation. Aniline (the product of phenyl isocyanate and water) was detected in the reaction of equivalent amounts of phenyl isocyanate and water in acetonitrile.     

Synthesis,characterization and thermal degradation kinetics of ferrocene‐containing aramids

Low‐temperature solution‐phase polycondensation of 1,1′‐ferrocenedicarboxylic acid chloride with different aromatic diamines was carried out in tetrahydrofuran in the presence of triethylamine to afford ferrocene‐containing aramids. The products were characterized by their solubilities, inherent viscosities, elemental analysis, FTIR spectroscopy, differential scanning calorimetry and thermogravimetry. All of them were insoluble in common solvents tested, except aramid‐IV (derived from 1,8‐naphthalene diamine), which was slightly soluble in N,N′‐dimethylacetamide, N,N′‐dimethylformamide, dimethylsulfoxide and formic acid. However, all were miscible with concentrated H₂SO₄, forming red‐coloured solutions. These all show a reduction in their solution viscosities at ambient conditions in concentrated H₂SO₄ which may be attributed to their non‐Newtonian behaviour. The glass transition temperature for each aramid was quite high, and stable up to 390 °C. The integral procedural decomposition temperatures for the products were calculated using Doyle's method and were found to be intermediate to that of Nylon 66 (419 °C) and Teflon (555 °C), and the activation energy for decomposition of each product was calculated by the Horowitz and Metzger method. Copyright © 2005 John Wiley & Sons, Ltd.     

Polyimides derived from bismethylolimides. II. Polyamine-imides from bismethylolimides and diamines

Compounds in the N-methylolimide group reacted smoothly with amines in the presence of water to yield the corresponding condensation products. Polycondensations of bismethylolimides, N,N′-bismethylolpyromellitic diimide, and N,N′-bismethylolbenzophenonetetracarboxylic diimide, with amines such as aromatic diamines, piperazine, and n-butylamine, were carried out in DMAc that contained 1% water to produce linear polyamine-imides. The polyamine-imides assumed various colors, from very pale yellow to deep purple, and had inherent viscosities in the 0.07–0.37-dl/g range. Most of these polymers were soluble in polar solvents such as DMAc and DMSO. The thermal stability of the polymers was examined by thermogravimetric analysis; decomposition started at 210–350°C and weight residue at 500°C was 22–85% in air.     

Highly stable electrochromic polyamides based on N,N‐bis(4‐aminophenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine

A new triphenylamine‐containing aromatic diamine monomer, N,N‐bis(4‐aminophenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine, was synthesized by an established synthetic procedure from readily available reagents. A novel family of electroactive polyamides with di‐tert‐butyl‐substituted N,N,N′,N′‐tetraphenyl‐1,4‐phenylenediamine units were prepared via the phosphorylation polyamidation reactions of the newly synthesized diamine monomer with various aromatic or aliphatic dicarboxylic acids. All the polymers were amorphous with good solubility in many organic solvents, such as N‐methyl‐2‐pyrrolidinone (NMP) and N,N‐dimethylacetamide, and could be solution‐cast into tough and flexible polymer films. The polyamides derived from aromatic dicarboxylic acids had useful levels of thermal stability, with glass‐transition temperatures of 269–296 °C, 10% weight‐loss temperatures in excess of 544 °C, and char yields at 800 °C in nitrogen higher than 62%. The dilute solutions of these polyamides in NMP exhibited strong absorption bands centered at 316–342 nm and photoluminescence maxima around 362–465 nm in the violet‐blue region. The polyamides derived from aliphatic dicarboxylic acids were optically transparent in the visible region and fluoresced with a higher quantum yield compared with those derived from aromatic dicarboxylic acids. The hole‐transporting and electrochromic properties were examined by electrochemical and spectro‐electrochemical methods. Cyclic voltammograms of the polyamide films cast onto an indium‐tin oxide‐coated glass substrate exhibited two reversible oxidation redox couples at 0.57–0.60 V and 0.95–0.98 V versus Ag/AgCl in acetonitrile solution. The polyamide films revealed excellent elcterochemical and electrochromic stability, with a color change from a colorless or pale yellowish neutral form to green and blue oxidized forms at applied potentials ranging from 0.0 to 1.2 V. These anodically coloring polymeric materials showed interesting electrochromic properties, such as high coloration efficiency (CE = 216 cm²/C for the green coloring) and high contrast ratio of optical transmittance change (ΔT%) up to 64% at 424 nm and 59% at 983 nm for the green coloration, and 90% at 778 nm for the blue coloration. The electroactivity of the polymer remains intact even after cycling 500 times between its neutral and fully oxidized states. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2330–2343, 2009     

Synthesis of Aluminum‐Rich Analcime Using an Ethylene Diamine Derivative as Template

The hydrothermal synthesis of analcime (ANA) with N,N′‐dibenzyl‐N,N,N′,N′‐tetramethylethylenediamine (DBTMED) as template was systematically studied. The various parameters that affect the crystallization of analcime, such as temperature, time, Al source, and Si/Al ratio were investigated. Systematic variations of these parameters revealed that ANA was obtained from the reaction mixture with the optimized ratios of SiO₂/Al₂O₃ = 5–9.5 in presence of DBTMED, whereas template‐free clear solution methods require SiO₂/Al₂O₃ ratio of greater than 25. When experiments were conducted at 130 and 150 °C for 4 days, a mixture of analcime and zeolite P was present in the samples, and a pure analcime sample could be obtained with heating in the temperature range 160–180 °C. When microwave and conventional heating were used, analcime could be obtained after 2 days. The obtained products were characterized by XRD, SEM, and IR spectroscopy.     

Studies on the hydrolysis of cyclophosphamide II. Isolation and characterization of intermediate hydrolytic products

Two new products of hydrolysis of cyclophosphamide in water at 100°, N-(2-chloroethyl)-N' -(3-phosphatopropy l)ethylenediamine and N-(2-hydroxyethyl)-N -(3-phosphatopropyl)ethylene-diamine, have been isolated after 30 minutes, and 6 hours of reaction times, respectively. These products have been shown to be intermediates leading to the formation of N-(2-hydroxyethyl)-N'-(3-hydroxypropyl)ethylenediamine, the principal ultimate product of cyclophosphamide hydrolysis. The nature of these new products supports the previously postulated mechanism involving an intramolecular alkylation as the initial step in the hydrolytic process although the pathway appears to be an unlikely model for the metabolic transformations of cyclophosphamide in vivo.     

Copper(I) 3-Methylsalicylate Mediates the Chan–Lam N-Arylation of Heterocycles

Copper(I) 3-methylsalicylate (CuMeSal) mediates N-arylation reactions between aryl boronic acids and aromatic heterocycles (Chan–Lam coupling) under moderate reaction conditions (K₂CO₃, methanol, 65 °C, in air, 3–5 h). Both electron-rich and electron-deficient aryl boronic acids and a diverse set of N-heterocycles were allowed to react and gave N-arylation products in reasonable yields, which demonstrate the utility of this catalyst.     

Cyclic Amine/Borane Lewis Pairs by the Reaction of N,N‐Diallylaniline with Lancaster′s H2B‐C6F5 Reagent

Twofold hydroboration of N,N‐diallylaniline with the C₆F₅BH₂?SMe₂ reagent gave the respective hetero‐bicyclo[3.3.0]octane and hetero‐methylbicyclo[3.2.0]heptane compounds 4 and 5 as the major products, both showing strong internal N‐B amine Lewis base/borane Lewis acid adduct formation. A DFT analysis indicated their formation (and that of a small amount of several isomeric five‐membered heterocyclic products) under thermodynamic control. Compound 5 underwent fragmentation with propene liberation to form compound 7 with a formal N=B bond at 100 °C. This product was also obtained from the isomer 4 at much higher temperature (300 °C).     

Synthesis of N-substituted bisitaconimide monomers for use as thermosetting polyimide resins

Two monomeric N-substituted bisitaconimides, N,N′-bisitaconimido-p,p′-diphenylmethane and N,N′-bis(itaconimido-p,p′-diphenyl ether), were synthesized from the corresponding diamines. The synthesis was accomplished by reaction of the diamine with itaconic anhydride and cyclocondensation of the resultant bisitaconamic acid. Attempts to use p,p′-diaminodiphenylsulfone as the diamine gave N,N′-biscitraconimido-p,p′-diphenylsulfone and N-citraconimido-N′-itaconimido-p,p′-diphenylsulfone instead of the bisitaconimide. The two bisitaconimides polymerize thermally at 180°C and 225°C, respectively, and yield tough polymers with very high thermal stability.     

Homogeneous Solution Reverse Atom Transfer Radical Polymerization of Methyl Methacrylate

A homogeneous reverse atom transfer radical polymerization (RATRP) of methyl methacrylate (MMA) was successfully carried out in N, N-dimethylformamide(DMF) (25%, v/v) at 69°C, using an initiating system azobisisobutyronitrile (AIBN)/CuBr₂/N, N, N′, N″, N″-pentamethyldiethylenetriamine (PMDETA). The kinetics of homogeneous solution polymerizations showed linear first-order rate plots, indicating a constant number of growing species throughout the polymerization as well as a negligible contribution of termination or transfer reactions; a linear increase of the number-average molecular weight with conversion, and relatively low polydispersities, but low initiator efficiency. The dependence of the rate of polymerization on the concentrations of initiator, catalyst, ligand and temperature were presented.     

Intramolecular diels-alder reactions. 4. Additions to naphthalene

N-Methyl-N-2-propynyl-1-naphthalenecarboxamide, N-methyl-N-2-propynyl-1-naphthaleneacetamide, and N-methyl-N-3-butynyl-1-naphthalenecarboxamide undergo intramolecular Diels-Alder reactions at 190°, 250°, and 270° to give lactams 1,6 , and 9 , respectively. The cyclization temperatures are higher by 80-120° as compared to those of the corresponding anthracene derivatives. Elaboration of lactam 6 gave the trans-4a-aryldecahydroisoquinoline derivative 7a which, as the (-) isomer, was shown to have the same absolute stereochemistry as morphine.     

Merger of Visible Light Induced Oxidation and Enantioselective Alkylation with a Chiral Iridium Catalyst

A single chiral octahedral iridium(III) complex is used for visible light activated asymmetric photoredox catalysis. In the presence of a conventional household lamp and under an atmosphere of air, the oxidative coupling of 2‐acyl‐1‐phenylimidazoles with N,N‐diaryl‐N‐(trimethylsilyl)methylamines provides aminoalkylated products in 61–93 % yields with high enantiomeric excess (90–98 % ee). Notably, the iridium center simultaneously serves three distinct functions: as the exclusive source of chirality, as the catalytically active Lewis acid, and as a central part of the photoredox sensitizer. This conceptionally simple reaction Scheme may provide new avenues for the green synthesis of non‐racemic chiral molecules.     

Kinetics of basic hydrolysis of tris(1,10‐phenanthroline)iron(II) in macromolecular assemblies of CTAB

The kinetics of basic hydrolysis of tris(1,10‐phenanthroline)iron(II) has been carried out in aqueous, N‐cetyl‐N,N,N‐trimethyl ammonium bromide (CTAB) micellar, and CTAB reverse micellar media by UV–visible spectroscopy system. The reaction follows the overall second‐order kinetics; first order in each Fe(II) complex and the base (^?OH). CTAB micelles catalyze the reaction rate through the adsorption of the Fe(II) complex and the hydroxyl ions on the micellar surface. In the reverse micellar medium, interesting physicochemical features are observed. Being ionic nature of reactants, both the reactants prefer to stay and react inside the water pool in place of the hydrophobic environment. The rate increases with w, that is, the size of the water pool, attains a maximum value at w = 8.33, and then decreases. But the rate increases as the concentration of surfactant increases at fixed w values. For a better explanation of the kinetic data, the activation parameters, standard enthalpy of activation (Δ^?H°), standard entropy of activation (Δ^?S°), and energy of activation (E_a) were determined. All kinetic data corroborate the proposed mechanism. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 579–589, 2011     

Anionic polymerization of N-ethyl-2-vinylcarbazole and N-ethyl-3-vinylcarbazole

The polymerization of N-ethyl-2-vinylcarbazole and N-ethyl-3-vinylcarbazole by an anionic mechanism has been demonstrated. Polymerization reactions were monitored by ultraviolet/visible spectroscopy and λ_max and ε values for the propagating carbanions determined. The 2-vinyl monomer exhibits all the features of a standard “living” polymer; the carbanion is stable at ambient temperatures and high molecular weight, M?_n ? 10⁶, narrow distribution polymers and block copolymers with styrene have been prepared. The carbanion from the 3-vinyl monomer is much less stable and a clean polymerization can only be conducted at temperatures below -60°C. A comparison of the anionic polymerization characteristics of the N-, 2-, and 3-vinyl carbazole monomer series is presented.     

Gas-phase thermolysis of N-cyanomethyl-N-ethyl aniline,N-cyanomethyl-N-ethyl-p-anisidine,and N-cyanomethyl-N-ethyl-p-nitroaniline

N-cyanomethyl-N-ethyl aniline (CEAN) and N-cyanomethyl-N-ethyl-p-anisidine (CEPA) have been thermolyzed in a stirred-flow reactor, in the range of 510–560 °C, pressures of 7–11 torr and residence times of 0.5–0.9 s, using toluene as carrier gas. N-cyanomethyl-N-ethyl-p-nitroaniline (ECNA) was thermolyzed at 640°C and 13% conversion. Ethylene and HCN formed in 43% yield each as products from all three starting materials. Phenyl methanaldimine and p-anisidyl methanaldimine were also products of CEAN and CEPA, respectively. The consumption of CEAN and CEPA showed first-order kinetics for a three-fold increase of reactant inflow and initial conversions of up to 40 percent. The following Arrhenius equations were obtained from the rate coefficients for the production of ethylene: CEAN: k=10^15.10±0.74 exp(−238±11 kJ/mol·RT); CEPA: k=10^15.61±0.29 exp(−246±4 kJ/mol·RT). The results are explained by means of radical, nonchain thermolysis mechanisms. The thermochemistry of relevant reaction steps has been estimated from thermochemical parameters calculated by using the semiempirical AM1 method. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 451–456, 1998     

Click synthesis and reversible electrochromic behaviors of novel polystyrenes bearing aromatic amine units

Novel electrochromic polymers were prepared by the click postfunctionalization of poly(4‐azidomethylstyrene) with alkyne‐containing aromatic amine units in the presence of Cu(I) catalysts. Two kinds of aromatic amine units, tris(4‐alkoxyphenyl)amine and N,N,N′,N′‐tetraphenyl‐p‐phenylenediamine, were introduced into polystyrene side chains, which were completely characterized by gel permeation chromatography–multiangle light scattering, nuclear magnetic resonance, and infrared spectroscopies, and elemental analysis. Thermal analyses demonstrated the high stability with the decomposition temperatures exceeding 300 °C even after postfunctionalization. The UV–vis absorption spectra of the polymer thin films revealed negligible absorption in the visible region, as reasonably confirmed by visual observation. The polymer thin films were prepared by spray‐coating on an indium tin oxide‐coated glass plate. Cyclic voltammograms of these films exhibited anodic peaks ascribed to the oxidation of the side‐chain aromatic amine moieties. The tris(4‐alkoxyphenyl)amine unit displayed one‐step oxidation at 0.287 V (vs. Ag/AgCl), while the N,N,N′,N′‐tetraphenyl‐p‐phenylenediamine unit showed two‐step oxidations at 0.297 and 0.641 V. These oxidation processes produced new colors of the polymer films. The former triarylamine‐based chromophore provided a blue color after the oxidation, while the latter phenylenediamine‐based chromophore showed a potentially controlled green and dark blue colors. The reversibility and switching behaviors of these color changes were also comprehensively investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012