Novel anionic polyaddition of 2‐trifluoromethylacrylate by double Michael reaction with ethyl cyanoacetate

Novel fluorinated polymer synthesis with anionic polyaddition by double Michael addition reaction of 2‐trifluoromethylacrylate derivatives with ethyl cyanoacetate (ECA) was proposed. Diaddition product of ECA with phenyl 2‐trifluoromethylacrylate was yielded in high yield by the catalysis of sodium ethoxide in tetrahydrofuran at 60 °C. Sodium hydroxide catalyzed double Michael addition reaction also produced diaddition product in high yield. Novel anionic polyaddition of 1,4‐phenylene bis(2‐trifluoromethylacrylate) [CH₂?C(CF₃)COOC₆H₄OCOC(CF₃)?CH₂] (PBFA) with ECA afforded the polymer of 1.2 × 10⁴ as the highest molecular weight. The isolated polymer gave the polymer of 2.8 × 10⁴ as a molecular weight by the reaction of the isolated polymer with PBFA in the presence of sodium ethoxide; which proved that the polymer end groups were mainly ECA moieties. The reaction mechanism that the proton abstraction from ECA followed by the addition of 2trifluoromethylacrylate was proposed. The reaction of acetylacetone with PBFA was also examined to give the polymer of 7.6 × 10³ as the highest molecular weight catalyzed by sodium hydroxide at room temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5698–5708, 2009     

NMR studies on the reaction between methacrylonitrile and trimethylaluminum

The reaction of MAN with AlMe₃ was studied by the ¹³C- and ¹H-NMR spectral measurement. In the presence of an excess of AlMe₃, it was found that a 1:1 complex of MAN and AlMe₃ is initially formed and subsequently dimethyl(α-methyl isopropylidene amino)aluminum is produced by the reaction of the complex with AlMe₃. The isolated product was pale yellow crystal (mp 39–40°C). The kinetics of the reaction were also examined.     

Reactions of 3-cyanochromones with primary amines: structures of the products

Reactions of 3-cyanochromones with primary aromatic amines in boiling benzene gave mixtures of Z- and E-3-arylamino-2-(2-hydroxyaroyl)acrylonitriles and 2-amino-3-(aryl-iminomethyl)chromones. The latter can easily be obtained in the individual state when the reaction is carried out in the presence of triethylamine. In the case of primary aliphatic amines, the open-chain reaction product immediately undergoes cyclization into 3-alkyliminomethyl-2-aminochromones. The structures of the products were examined by 1D and 2D ¹H, ¹³C, and ¹⁵N NMR spectroscopy in DMSO-d₆ and CDCl₃.     

Chelate von Chinolin-8-ol — Derivaten. XI. Eigenschaften und Struktur von Nickelchelaten alkyl-substituierter Chinolin-8-ole bzw. Chinolin-8-thiole

Reactions of 1,1,3,3-Tetrakis(dimethylamino)-1λ⁵,3λ⁵-diphosphete with N? H and P? H Acidic Compounds 1,1,3,3-Tetrakis(dimethylamino)-1λ⁵,3λ⁵-diphosphete, 1 , reacts with aniline to give by opening of the ring 2,2,4,4-tetrakis(dimethylamino)-1-phenyl-1,2λ⁵,4λ⁵-azadiphosphapenta-1,3-diene, 2 , with p-CN? C₆F₄? NH₂ the product is 1-(4-cyano-2,3,5,6-tetrafluorophenyl)-2,2,4,4-tetrakis(dimethylamino)-1,2λ⁵,4λ⁵-azadiphosphapenta-1,3-diene, 3 . t-Butylamine or diethylamine do not react with 1 . Mesitylphosphane opens the ring system 1 forming by reduction of one phosphorus atom {[bis(dimethylamino)phosphanyl]methylidene}bis(dimethylamino)methylphosphorane, 4 . The same product 4 is obtained by reaction with phenylphosphane. The reaction products 2–4 are characterized by their nmr, mass, and ir spectra. Their way of formation is discussed. In 4 a ⁵J(PH), in 3 a ⁷J(CF) long range coupling constant could be identified.     

Atmospheric photooxidation of isoprene part II: The ozone-isoprene reaction

A series of experiments have been performed to study the ozone-isoprene reaction in a smog chamber by adding externally produced O₃ to the hydrocarbon in the dark. A chemical tracer, methyl cyclohexane, was added to probe the OH formation in the system. O(³P) formation was also examined using the known distribution of products that are unique to the O(³P)-isoprene reaction (part I). The results provide clear evidence that both OH and O(³P) are produced by the O₃-isoprene reaction directly in large quantities; about 0.68 ± 0.15 and 0.45 ± 0.20 per O₃-isoprene reaction, respectively. These additional radicals severely complicate the analysis of the O₃ reaction, hence, computer kinetic modeling was necessary to ascertain the products of the O₃ reaction itself, corrected for OH and O(³P) reactions. The product distribution, which differs dramatically from that published previously, is: 67 ± 9% methacrolein, 26 ± 6% methyl vinyl ketone, and 7 ± 3% propene, accounting for 100 ± 10% of the reacted isoprene. Applicability of these results to the gas-phase O₃ reaction with other unsaturated hydrocarbons is briefly discussed.     

Electron transfer. 121. Oxidations by Rhodium-Bound Superoxide

The violet superoxo complex, [(H₂O)₄(OH)Rh^III(O₂)Rh^III(OH)(H₂O)₄]³⁺, formed by treatment of (Rh^II)₂⁴⁺ with O₂ in HClO₄, is converted to a le^? reduction product, the corresponding μ-peroxo complex, by the reductants I^?, IrCl₆^3?, and the trinuclear aquamolybdenum(III) cation, (Mo^III)₃. Each reaction is first-order in both redox partners, and the le^? reduction by IrCl₆^3? is followed by a much slower conversion to a peroxide-free complex. Among the rapid reductions of the superoxo derivative examined here and in a previous study, only that by IrCl₆^3? is accelerated by increases in acidity; the rate law for this reaction features both an acid-independent and a [H⁺]-proportional component, the latter stemming from partial conversion of the oxidant to its conjugate acid (pK_A < ?1.0). Rate laws for reductions by other metal-center reagents generally exhibit inverse-[H⁺] terms, reflecting deprotonation of the reductant. All reductions thus far observed involving this superoxo species appear to be outer-sphere. Treatment of acid-independent rate constants within the framework of the Marcus model, allows estimates of the self-exchange rate, k₁₁, for the (Rh^III)₂-bound superoxo-peroxo couple. Because values of k₁₁ calculated from the several reductions span a range of 10^4.5, reductions of the superoxo complex cannot be taken to conform satisfactorily to the Marcus treatment, being in this respect comparable to the systems VO(OH)^+/2+, Mn^2+/3+, Eu^2+/3+, and Ti(OH)^2+/3+, each of which exhibits similar divergences. The wide range of calculated self-exchange rates appears to invalidate an earlier suggestion that reduction of the superoxo complex by Fe²⁺ proceeds primarily through a bridged path. © 1994 John Wiley & Sons, Inc.     

Reaction of Metal Alkoxides with Lysine: Substitution of Alkoxide Ligands vs. Lactam Formation

Summary. Reaction of Ti(OEt)₄ with lysine results in the formation of Ti(OEt)₃(lysinate), as previously reported. Contrary to that, Al(O^sBu)₃ only catalyzes the formation of 3-aminocaprolactam, and no substitution product was observed. The reaction of Zr(OBu)₄ with lysine at room temperature produced both 3-aminocaprolactam and Zr(OBu)₃(lysinate); the lysinate complex was not observed when the reaction was performed at elevated temperatures.Received February 17, 2003; accepted February 21, 2003 Published online June 12, 2003     

Rhodium catalyzed hydroacylation of ethylene with 4-pentenals. reactions of 4-hexenal-1-d

A catalyst derived from 2,4-pentanedionatobis(ethylene)rhodium(I), I, promoted the addition of 4-pentenal to ethylene. The reaction was accompanied by the formation of double bond migration products derived from the 4-pentenal reactant and from the 6-hepten-3-one primary product. Compound I accomplished the addition of 4-hexenal to ethylene to afford high yields of 6-octen-3-one. The fate of the aldehyde hydrogen in this transformation has been determined in experiments employing 4-hexenal-1-d as reactant. Treatment of 4-hexenal-1-d with I in CHCl₃ and CDCl₃ afforded 6-octen-3-one possessing >50% d_o molecules while the isotopic composition of recovered unexpended 4-hexenal remained >96% d₁. 6-Octen-3-one products with isotopic compositions of >66% d_o were afforded when ethylene was introduced to reaction mixtures. The location of deuterium in 6-octen-3-one, derived from treatment of 4-hexenal-1-d with I in the absence of added C₂H₄, was determined to be distributed at C-1 and C-2 and at the CC bond by analysis of the ¹H and ²H NMR spectra. Unexpended ethylene was recovered and was found to contain a substantial amount of deuterium. Mechanistic implications of these results are discussed.     

Enzyme-catalyzed reaction of voltammetric enzyme-linked immunoassay system based on OAP as substrate

The o-aminophenol (OAP)-H_2O_2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay new system has extremely high sensitivity. HRP can be measured with a detection limit of 6.0×10~-(10) g/L and a linear range of 1.0×10~(-9)—4.0×10~(-6) g/L. The pure product of H_2O_2 oxidizing OAP catalyzed by HRP was prepared with chemical method. The enzyme-catalyzed reaction has been investigated with electroanalytical chemistry, UV/Vis spectrum, IR spectrum, ~(13)C NMR, ~1H NMR, mass spectrum, elemental analysis, etc. Under the selected enzyme-catalyzed reaction conditions, the oxidation product of OAP with H_2_O2 catalyzed by HRP is 2-aminophe-noxazine-3-one. The processes of the enzyme-catalyzed reaction and the electroreduction of the product of the enzymecatalyzed reaction have been described.     

Reactivity of [Ni(cod)2][Al(ORF)4] towards Small Molecules and Elements

To provide a better understanding of the recently published pure metalorganic Ni^I species, [Ni(cod)₂][Al(OR^F)₄] ( 1 ) [cod = 1,5‐cyclooctadiene, R^F = C(CF₃)₃], further characterizations were performed and analyzed. Thus, the solvation of 1 in THF was examined by EPR, surprisingly disclosing the initiation of a disproportionation reaction to [Ni^II(THF)₆][Al(OR^F)₄]₂ ( 3 ) and Ni⁰. Further studies concerning the ability of 1 to activate small molecules exhibit the formation of a remarkable [Ni₃S₂(cod)₃]²⁺ cluster ( 5 ) in an oxidation reaction with S₈, while EPR measurements of the resulting product in a reaction with oxygen indicate a possible coordination of O₂. Single crystal X‐ray structures as well as spectroscopic analyses of 3 and 5 are described.     

Theoretical investigation of ion pair SN2 reactions of alkali isothiocyanates with alkyl halides. Part 1. Reaction of lithium isothiocyanate and methyl fluoride with inversion mechanism

The gas‐phase ionic S_N2 reactions NCS^‐ + CH₃F and ion pair S_N2 reaction LiNCS + CH₃F with inversion mechanism were investigated at the level of MP2(full)/6‐311+G**//HF/6‐311+G**. Both of them involve the reactants complex, inversion transition state, and products complex. There are two possible reaction pathways in the ionic S_N2 reaction but four reaction pathways in the ion pair S_N2 reaction. Our results indicate that the introduction of lithium significantly lower the reaction barrier and make the ion pair displacement reaction more facile. For both ionic and ion pair reaction, methyl thiocyanate is predicted to be the major product, but the latter is more selective. More‐stable methyl isothiocyanate can be prepared by thermal rearrangement of methyl thiocyanate. The theoretical predictions are consistent with the known experimental results. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Rate coefficient for the reaction: Br+Br2O→Br2+BrO

The room temperature rate coefficient for the reaction Br+Br₂O→Br₂+BrO (3) has been measured using the technique of pulse-laser photolysis with long-path transient absorption detection of the BrO reaction product. A value of k₃=(2.0±0.5)×10⁻¹⁰ cm³ molecule⁻¹ s⁻¹ was determined. The photolysis products of Br₂O at 308 nm were also examined. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 571–576, 1998     

Reduction Process of Tetraplatin in the Presence of Deoxyguanosine Monophosphate (dGMP): A Computational DFT Study

The reduction mechanism of [Pt^IV(dach)Cl₄] (dach=diaminocyclohexyl) in the presence of dGMP was studied. The first step is substitution of a chloro ligand by dGMP, followed by nucleophilic attack of a phosphate or sugar oxygen atom to the C8‐position of guanine. Subsequent reduction forms the [Pt^II(dach)Cl₂] complex. The whole process is completed by a hydrolysis. Two different pathways for the substitution reaction were examined: a direct associative and a Basolo–Pearson autocatalytic mechanism. All the explored structures were optimized at the B3LYP‐D3/6‐31G(d) level and by using the COSMO solvation model with Klamt's radii. Single‐point energetics was determined at the B3LYP‐GD3BJ/6‐311++G(2df,2pd)/PCM/scaled‐UAKS level. Activation barriers were used for an estimation of the rate constants and these were compared with experimental values. It was found that the rate‐determining step is the nucleophilic attack with a slightly faster performance in the 3′‐dGMP branch than in the case of 5′‐dGMP with activation barriers of 21.1 and 20.4 kcal mol^?1 (experimental: 23.8 and 23.2 kcal mol^?1). The reduction reaction is connected with an electron flow from guanine. The product of the reduction reaction is a chelate structure, which dissociates within the last reaction step, that is, a hydrolysis reaction. The whole redox process (substitution, reduction, and hydrolysis) is exergonic by 34 and 28 kcal mol^?1 for 5′‐dGMP and 3′‐dGMP, respectively.     

Electrochemical Studies of Tantalum(V) Chlorides and Bromides in Acetonitrile. Electrochemical Generation of Tantalum(IV) Species

The electrochemical properties of tantalum halides, TaX₅ Et₄NTaCI₆ and Bu₄NTaBr₆ (X = Cl^? and Br^?) were investigated in rigorously dried acetonitrile using cyclic voltammetry and constant potential electrolysis. A special vacuum electrochemical cel1 equipped with a sample loading device and an AI₂O₃ column was used in order to prevent the hydrolysis of tantalum halides with the small amount of water present in “dry” acetonitrile. Two one-electron reduction waves were observed for al1 tantalum(V) species which correspond to consecutive Ta(V) → Ta(IV) and Ta(IV) → Ta(III) reduction. The E_1/2 values for the Ta(V) → Ta(IV) reduction process are criticalIy dependent on the number of CI^? ligands coordinated to the tantalum atom. As the number of Cl^? is increased from 4 to 5 and 6, it becomes more difficult, by 0.4 V, to reduce Ta(V) to Ta(IV). Constant potential electrolysis at –20°C generates Ta(IV) species; thus TaCl₆ ^2-. TaBr₆ ^2-, TaCl₅NCMe^?, TaBr₅NCMe^? and TaCI₄(NCMe)₂, are obtained in acetonitrile solution after electrolysis. It was found that the reduction product of TaCl₅NCMe depends upon the temperature. At a higher temperature (0°C) the initial electron transfer step is fol1owed by a chemical reaction in which some of the product, TaCI₅NCMe^?, reacts with the starting material, TaCI₅NCMe. to produce TaCl₆ ^? and TaCl₄(NCMe)₂. At lower temperatures (–20°C) the rate of the folIowing chemical reaction is much slower and the reduction product is almost exclusively TaCl₅NCMe^?.     

Synthesis and Characterization of Iron,Cobalt, and Nickel [PNP] Pincer Amido Complexes by N–H Activation

The N–H bond activation product [PNP]‐Fe^I(PMe₃)₂ ( 2 ) was obtained at room temperature by the reaction of diphosphinito [PNP] pincer ligand ((Ph₂P(C₆H₄))₂NH ( 1 )) with Fe(PMe₃)₄. Treatment of 1 with Co(PMe₃)₄, CoCl(PMe₃)₃ and CoMe(PMe₃)₄ afforded the same N–H bond activation product [PNP]‐Co^I(PMe₃)₂ ( 3 ). In order to have a better understanding of the mechanism of formation of 3 , in situ IR and ¹H NMR spectroscopic investigations were conducted.The reaction of 1 with Ni(PMe₃)₄ afforded the ligand replacement complex 4 while a [PNP]‐Ni^IIMe complex 5 was obtained via deprotonation through the reaction of 1 with NiMe₂(PMe₃)₃. The molecular structures of 2 – 4 were confirmed by X‐ray diffraction analysis.     

Darstellung intramolekular stabilisierter Diazaphosphorinan-Derivate mit der Trimethylethylendiamin- bzw. der Tetramethylguanidingruppe als Substituent am Phosphor: Studium intramolekularer Me2N → P-Wechselwirkungen

Formation of Intramolecularly Stabilized Diazaphosphorinane Derivatives with the Trimethylethylenediamine and the Tetramethylguanidine Group as Substituents at Phosphorus: Investigation of intramolecular Me₂N → P Interactions In the reaction of trimethylchlorophosphonium chloride 1 with N-trimethylsilyl-N′,N′,N″,N″-tetramethylguanidine 2 the expected guanidine-substituted trimethylphosphonium chloride 3 was formed, presumably via the ammonium chloride 3a which could not be isolated. By contrast, the reaction of the related chloromethyldimethylchlorophosphonium chloride 5 with N-trimethylsilyl-N,N′,N′-trimethylethylenediamine 6 and N-trimethylsilyl-N′,N′-dimethylethylene diamine, 7 , respectively, furnished in an unusual fashion six-membered heterocycles, the ammonium-phosphonium dichlorides 10 and 11 . Their formation involved cleavage of both the P? Cl and the C? Cl bond, followed by intramolecular C←N-acceptor-donor interaction. A similar C←N interaction was not observed in the reaction of 5 with 2 , and the acyclic product 12 was formed. The reaction of chloromethylmethylchlorophosphine 13 with the hydrogen peroxide/urea 1:1-adduct led to chloromethylmethylphosphinic acid 14 . Attempts at the reaction of 14 with 2 or with SOCl₂ were unsuccessful. The reaction products were characterized by ¹H-, ¹³C-, ³¹P- and, in two cases, by ¹⁵N-NMR-spectroscopy.     

C3H2环丙烯基自由基与O(3P)反应机理的理论研究

本文用量子化学密度泛函方法对C3H2 (环丙烯基自由基)与O(3P)反应的机理进行了理论研究。在B3LYP/6-311++G**计算水平上优化了各驻点（过渡态,中间体,产物）的几何结构,在QCISD(T)/6-311++G**水平下计算了各物质的单点能量,在两种水平下计算了298K和600K时的能量。计算结果表明：C3H2 + O(3P) 反应可以生成P1 (C2H +HCO),P2 (C2H2 + CO) 和P3 (HC3O+H)三种产物。生成P1反应通道的能垒最低,即P1为主要产物,与实验的结果一致。产物P1可以通过路径：R→ IM1→ IM2→ P1获得。本文详细地讨论了C3H2 + O(3P) 的反应机理,并从理论上对实验结果进行了验证。研究结果有助于深入理解C3H2 + O(3P)反应机理以及C3H2在大气中的燃烧过程。     

A Low‐Temperature Synthesis Route for CaAlSiN3 Doped with Eu2+

A new low‐temperature synthesis route of the strongly red‐emitting Eu²⁺ activated nitride phosphor CaAlSiN₃ is presented. The fluorides CaSiF₆ and AlF₃ were used as a source of metal ions and Li₃N as a nitrogen source. A KCN/LiCl flux system was employed to lower the temperature of the reaction from 1100 to 750 °C. The course of the reaction was studied by differential thermal analysis, and the product of the reaction was inspected by X‐ray powder diffraction and luminescence measurements of CaAlSiN₃:Eu.     

Radical polyaddition reaction of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate onto diformylalkane

Radical polyaddition of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF₂C(CF₃)OCOC₆H₄COOC(CF₃)CF₂] (BFP) with diformylalkanes to produce fluorinated polymer bearing ketone-carbonyl groups in main chain is described. The radical additions of hexanal, pentanal and benzaldehyde with 2-benzoxypentafluoropropene [CF₂C(CF₃)OCOC₆H₅] were examined as model reactions to yield the corresponding addition product with hexanal and pentanal in high yields, and no product with benzaldehyde. The addition of acyl and hydrogen was found to take place to perfluoroisopropenyl group. The results of the model reactions suggested that the reaction might be applicable to polyaddition to produce polymers with diformylalkanes. The results of polyaddition of BFP with glutaraldehyde under the emulsion polymerization condition showed that the polymer of M_n=4.8×10³ was obtained in fairly high yields. This might be a novel preparation method of polymers bearing fluorinated polyketone structure.     

Mechanistic study of 7-endo selective radical cyclization of the aryl radical

Mechanistic studies on the novel 7-endo selective radical cyclization were carried out. The reaction afforded three products, 7-endo product, 6-exo product, and reduced product. The distribution of these products was estimated by GC analyses. The 7-endo/6-exo selectivity was almost constant against variation in the concentration of Bu₃SnH, while the reduction/cyclization ratio was sensitive to the concentration of Bu₃SnH. The reduction/cyclization ratio was mainly affected by the rotational isomeric ratio of the cyclization precursor. Kinetic analyses indicated that the cyclization process should be irreversible, and the rate constant of 7-endo/6-exo radical cyclization was estimated to be about 3.3 × 10⁸ s⁻¹ at 80 °C.