Mechanism study on the reactions between biphenyl and HNO<Subscript>2</Subscript> initiated by 355 nm irradiation in aqueous phase

The reactions taking place in the mixed solution of biphenyl and nitrous acid after it was exposed to UV irradiation were studied in this research work. The transient species were identified with the nanosecond transient spectroscopic technique, and the final products were ascertained by GC-MS analysis. It was shown that the OH radical, generated by the direct photolysis of nitrous acid, would attack biphenyl molecule to form Bp-OH adduct with a rate constant of 9.5×109 L·mol-1·s-1. The Bp-OH adduct could either react with H or be oxidized by nitrous acid to form nitrosobiphenol. The reactions between biphenyl and nitrous acid under UV irradiation in atmospheric aqueous phase were therefore suggested to be one promising source of nitrocompounds in the environment.     

二茂锆羧酸配合物的合成——二茂锆氢化物与α,β—不饱和酸或钠盐反应的研究

本文研究了Cp₂ZrH₂与丙烯酸和Cp₂Zr(H)Cl与丙烯酸钠、巴豆酸钠的反应。产物由IR ¹H和¹³CNMR、ESR谱、气相色谱以及化学方法分析鉴定。产物水解得到与底物相应的饱和酸.用¹H NMR方法考察了Cp₂ZrH₂与丙烯酸的反应过程,用IR方法考察了Cp₂Zr(H)Cl与丙烯酸钠的反应过程。实验结果表明,上面两种反应首先消除H₂或NaCl,形成锆氧健,然后碳碳双键还原生成二茂锆羧酸盐配合物,其中羧酸根离子与二茂锆桥式双齿配位。     

Preparation of metal bromoacetates from other salts by Solvolytic reactions in fused monobromoacetic acid

Solvolytic reactions between monobromoacetic acid and metal oxides, carbonates, oxalates, formates, sulphites, nitrates, nitrites and chlorides form monobromoacetates. In the case of transition metals, a molecule of solvent is also attached to the solvolysed products. The solvolysed products have been investigated by IR, magnetic susceptibility and molar conductance measurements. Lewis bases form adducts with these products. The solvolytic reactions have been explained on the bases of autoionization of monobromoacetic acid reported earlier¹ as, 2CH₂BrCOOH ? CH₂BrCOOH₂⁺+ CH₂BrCOO^?.     

The gas‐phase elimination kinetics of ethyl 2‐furoate and ethyl 2‐thiophenecarboxylate

The gas‐phase elimination kinetics of ethyl 2‐furoate and 2‐ethyl 2‐thiophenecarboxylate was carried out in a static reaction system over the temperature range of 623.15–683.15 K (350–410°C) and pressure range of 30–113 Torr. The reactions proved to be homogeneous, unimolecular, and obey a first‐order rate law. The rate coefficients are expressed by the following Arrhenius equations: ethyl 2‐furoate, log k₁ (s^?1) = (11.51 ± 0.17)–(185.6 ± 2.2) kJ mol^?1 (2.303 RT)^?1; ethyl 2‐thiophenecarboxylate, log k₁ (s^?1) = (11.59 ± 0.19)–(183.8 ± 2.4) kJ mol^?1 (2.303 RT)^?1. The elimination products are ethylene and the corresponding heteroaromatic 2‐carboxylic acid. However, as the reaction temperature increases, the intermediate heteroaromatic carboxylic acid products slowly decarboxylate to give the corresponding heteroaromatic furan and thiophene, respectively. The mechanisms of these reactions are suggested and described. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 145–152, 2009     

1,1‐Organoboration of bis(trimethylstannyl)ethyne with trimethylsilyl‐ and dimethylsilyl‐dialkylboryl‐substituted alkenes: organometallic‐substituted allenes

The reactions of bis(trimethylstannyl)ethyne, Me₃Sn–C?C–SnMe₃ ( 4 ), with trimethylsilyl‐ or dimethylsilyl‐dialkylboryl‐substituted alkenes 1 – 3 afford organometallic‐substituted allenes 5 , 6 and 8 , 9 in high yield. In the case of (E)‐2‐trimethylsilyl‐3‐diethylboryl‐2‐pentene ( 1) , a butadiene derivative 7 could be detected as an intermediate prior to rearrangement into the allene. All reactions were monitored by ²⁹Si and ¹¹⁹Sn NMR, and the products were characterized by an extensive NMR data set (¹H, ¹¹B, ¹³C, ²⁹Si, ¹¹⁹Sn NMR). Copyright © 2003 John Wiley & Sons, Ltd.     

Chemical Transformations of Tetracyclo[3.3.1.1<Superscript>3,7</Superscript>.0<Superscript>1,3</Superscript>]decane (1,3-Dehydroadamantane): VI. Reactions of 1,3-Dehydroadamantane with Carboxylic Acid Chlorides

1,3-Dehydroadamantane reacted with saturated carboxylic acid chlorides to give the corresponding 1-acyl-3-chloroadmantanes as the major products. In some cases, minor products of insertion into the C^α–H bond of acyl chloride were formed. The reactions of 1,3-dehydroadamantane with aromatic (heteroaromatic) carboxylic acid chlorides selectively afforded aryl (hetaryl) 3-chloroadamantan-1-yl ketones. The described reactions provide a synthetic route to difficultly accessible alkyl (aryl) ketones containing a 3-chloroadamantan- 1-yl group in one step under mild conditions with high yields.     

Distal γ-C(sp3)−H Olefination of Ketone Derivatives and Free Carboxylic Acids

Reported herein is the distal γ-C(sp³)−H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino-acid directing group and using the ligand combination of a mono-N-protected amino acid (MPAA) and an electron-deficient 2-pyridone were critical for the γ-C(sp³)−H olefination of ketone substrates. In addition, MPAAs enabled the γ-C(sp³)−H olefination of free carboxylic acids to form diverse six-membered lactones. Besides alkyl carboxylic acids, benzylic C(sp³)−H bonds also could be functionalized to form 3,4-dihydroisocoumarin structures in a single step from 2-methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ-C(sp³)−H olefinated products.     

Synthesis of oxime bearing cyclophosphazenes and their reactions with alkyl and acyl halides

Two novel cyclophosphazenes containing oxime groups were prepared from the hexakis(4‐formylphenoxy)cyclotriphosphazene ( 2 ) and hexakis‐(4‐acetylphenoxy)cyclotriphosphazene ( 7 ). The reactions of these oximes with acetyl chloride, chloroacetyl chloride, methyl iodide, propyl chloride, mono‐ chloroacetone, and 1,4‐dichlorobutane were studied. Hexasubstituted compounds were obtained from the reactions of hexakis(4‐[(hydroxyimino)methyl]phenoxy)cyclotriphosphazene ( 3 ) with acetyl chloride ( 4 ) and chloroacetyl chloride ( 5 ); however, tetrasubstituted product was obtained from methyl iodide ( 6 ). Tetra‐ and trisubstituted products were obtained from the reactions of hexakis(4‐[(1)‐N‐hydroxyethaneimidoyl]phenoxy)cyclotriphosphazene ( 8 ) with acetyl chloride ( 9 ) and chloroacetyl chloride ( 10 ), respectively. All products were obtained in high yields. Pure and defined product could not be obtained from the reaction of 8 with methyl iodide, and could not be also obtained from the reactions of 3 and 8 with propyl chloride, monochloroacetone, and 1,4‐dichlorobuthane. The structures of the compounds were defined by elemental analysis, IR, ¹H, ¹³C, and ³¹P NMR spectroscopy. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:112–117, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20176     

Distal γ‐C(sp3)−H Olefination of Ketone Derivatives and Free Carboxylic Acids

Reported herein is the distal γ‐C(sp³)?H olefination of ketone derivatives and free carboxylic acids. Fine tuning of a previously reported imino‐acid directing group and using the ligand combination of a mono‐N‐protected amino acid (MPAA) and an electron‐deficient 2‐pyridone were critical for the γ‐C(sp³)?H olefination of ketone substrates. In addition, MPAAs enabled the γ‐C(sp³)?H olefination of free carboxylic acids to form diverse six‐membered lactones. Besides alkyl carboxylic acids, benzylic C(sp³)?H bonds also could be functionalized to form 3,4‐dihydroisocoumarin structures in a single step from 2‐methyl benzoic acid derivatives. The utility of these protocols was demonstrated in large scale reactions and diversification of the γ‐C(sp³)?H olefinated products.     

Pyrolysis of β-hydroxyketones and α-ketoesters: Gas-phase elimination kinetics of 3-hydroxy-3-methyl-2-butanone and methyl benzoylformate

The rates of gas-phase elimination reactions of methyl benzoylformate ( 1 ) and 3-hydroxy-3-methyl-2-butanone ( 2 ) were obtained at T = 600 K. The two substrates undergo unimolecular first-order elimination for which the Arrhenius equations are, respectively, log k = 13.2 − 53270/(4.574 × 600) for ( 1 ) and log k = 12.4 − 53060/(4.574 × 600) for ( 2 ). The products of pyrolysis of ( 1 ) are benzaldehyde, formaldehyde and CO, while those of ( 2 ) are acetaldehyde and acetone. The kinetics of the elimination reactions show benzoylformic acid to be 10⁶-fold more reactive than ( 1 ), and pyruvic acid ca. 10⁵-fold more reactive relative to ( 2 ); an indication of the rate-controlling part played by the acidity of the hydrogen atom involved in the elimination process of the present compounds in this particular type of reaction. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 295–298, 1997.     

Chemistry of 1,5-diketones: II. Specificity of transformations of polycyclic 1,5-diketones in acid media

2-(1,3-Diaryl-3-oxopropyl)cyclohexan-1-ones underwent carbo-and heterocyclization in a mixture of acetic acid with acetic anhydride in the presence of perchloric acid. The transformation of 2-(1,3-diaryl-3-oxopropyl)cyclohexan-1-ones into 2,4-diaryl-5,6,7,8-tetrahydrochromenylium salts was shown to involve intermediate 2,4-diarylbicyclo[3.3.1]non-2-en-9-ones. The structure of 2,4-diaryl-substituted bicyclo[3.3.1]non-2-en-9-ones and products of their reactions with halogens and hydroxylamine hydrochloride was confirmed by ¹H and ¹³C NMR spectroscopy.     

Comprehensive Reinvestigation of The Reaction of D-Aldoses With Meldrum'S Acid Yielding Mainly Chain Extended 3,6-Anhydro-2-Deoxy-Aldono-1,4-Lactones

ABSTRACT

All diastereomeric aldo-D-pentoses and -D-hexoses were reacted with Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione) under basic conditions. A protocol was applied and optimized which was originally reported by J. A. Galbis Perez et al. in 1990. In every case formal substitution of the anomeric hydroxyl against a carboxy-methylene group occurred thus elongating the carbon chain of the parent aldose by a C₂ fragment. Products are mainly 3,6-anhydro-2-deoxy-aldono-1,4-lactones in which the lactone rings are annulated to a furanoid system. However, D-mannose and D-lyxose also gave pyranoid 3,7-anhydro-1,4-lactones. Intermediates are unsaturated open-chain 1,4-lactones (butenolides) which in some cases could be isolated as by-products. Epimerisation at C-2 of the parent aldose occurred at least partially in most reactions. The products and their acetylated derivatives were characterized by ¹H and ¹³C NMR spectroscopy. A proposed mechanism of this reaction is supported by additional experimental evidence.     

An Efficient Synthesis of 6′‐methyl‐1'H‐spiro[indoline‐3,4′‐pyrimidine]‐2,2′(3'H)‐dione Derivatives

The reactions of isatins, urea and 1‐(piperidin‐1‐yl)butane‐1,3‐dione or 1‐morpholinobutane‐1,3‐dione have been developed for the preparation of spiroheterocycles compounds. It was found these reactions could be given higher yields and required shorter time in our process. In this synthesis, some useful groups, such as pyridyl and morpholinyl were introduced into the structures of the products. The compounds were confirmed by IR, ¹H NMR, ¹³C NMR, and HRMS. Else, compounds 4i and 4r were additionally confirmed by X‐ray diffraction analysis. The other advantages of this procure were simple handling, high yields, and wide range substrates.     

Dediazoniation of Arenediazonium Ions. Part XXII. Reactions of 2, 6-Dialkyl-Substituted Benzenediazonium Ions in Super Acids,Acetonitrile and Acetone

Reactions of 2,4,6-trimethylbenzenediazonium ( 1 ), 2,6-diethylbenzenediazonium ( 2 ) and 2,6-diisopropylbenzenediazonium ( 3 ) tetrafluoroborates were studied in magic acid, SbF₅/SO₂ClF, acetonitrile and acetone by ¹H-NMR and by analysis of the dediazoniation products. The N_α-N_β rearrangement of β-N¹⁵-labelled tetrafluoroborates 1–3 was followed by ¹⁵N-NMR of the corresponding arylazonaphthols, as well as by MS analysis of the anilines obtained by reduction of the azo compounds. Diazonium salts 2 and 3 were synthesized for the first time and the steric effect of substituents at C(2) and C(6) on the reactions under study is discussed. All the results obtained can be rationalized by heterolytic dediazoniation of diazonium salts 1 – 3 and product formation from the corresponding aryl cations.     

Photodecomposition of iodopentanes in air: Product distributions from the self‐reactions of n‐pentyl peroxyl radicals

Product distributions from the 254‐nm photooxidation of the three iodopentane isomers were explored as a technique for studying the self‐reactions of individual pentyl peroxyl radicals (in air at ambient temperature and pressure). Pentanols and the associated carbonyl compounds (pentanal or pentanones) were major products as expected. Other major products resulted from the isomerization of pentan‐1‐oxyl and pentan‐2‐oxyl radicals, but their nature could not be identified. Minor products were alcohols and carbonyl compounds arising from the decomposition of pentoxyl radicals. Diols and mixed hydroxycarbonyl compounds from cross‐combination reactions were essentially absent, in contrast to expectation. The observed product distributions were evaluated to derive branching ratios for the radical‐preserving pathways of the self‐reactions, 0.42 ±0.17, 0.46 ± 0.10, 0.39 ± 0.08, for pentan‐1‐yl peroxyl, pentan‐2‐yl peroxyl, and pentan‐3‐yl peroxyl, respectively. Rate coefficients derived for the decomposition of the corresponding pentoxyl radicals, relative to their reaction with oxygen, are (5.1 ± 0.5) × 10¹⁸, (1.0 ± 0.2) × 10¹⁸, and (3.2 ± 0.3) × 10¹⁸ molecule cm^?3, respectively. Rate constants for the isomerization of pentan‐1‐oxyl and pentan‐2‐oxyl were estimated from the contributions of isomerization products to the total amounts of products as (4.0 ± 1.1) × 10⁵ s^?1 and (1.0 ± 2.0) × 10⁵ s^?1, respectively. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 126–138, 2002     

Heterogeneous versus Homogeneous Copper(II) Catalysis in Enantioselective Conjugate‐Addition Reactions of Boron in Water

We have developed Cu^II‐catalyzed enantioselective conjugate‐addition reactions of boron to α,β‐unsaturated carbonyl compounds and α,β,γ,δ‐unsaturated carbonyl compounds in water. In contrast to the previously reported Cu^I catalysis that required organic solvents, chiral Cu^II catalysis was found to proceed efficiently in water. Three catalyst systems have been exploited: cat. 1: Cu(OH)₂ with chiral ligand L1 ; cat. 2: Cu(OH)₂ and acetic acid with ligand L1 ; and cat. 3: Cu(OAc)₂ with ligand L1 . Whereas cat. 1 is a heterogeneous system, cat. 2 and cat. 3 are homogeneous systems. We tested 27 α,β‐unsaturated carbonyl compounds and an α,β‐unsaturated nitrile compound, including acyclic and cyclic α,β‐unsaturated ketones, acyclic and cyclic β,β‐disubstituted enones, acyclic and cyclic α,β‐unsaturated esters (including their β,β‐disubstituted forms), and acyclic α,β‐unsaturated amides (including their β,β‐disubstituted forms). We found that cat. 2 and cat. 3 showed high yields and enantioselectivities for almost all substrates. Notably, no catalysts that can tolerate all of these substrates with high yields and high enantioselectivities have been reported for the conjugate addition of boron. Heterogeneous cat. 1 also gave high yields and enantioselectivities with some substrates and also gave the highest TOF (43 200 h^?1) for an asymmetric conjugate‐addition reaction of boron. In addition, the catalyst systems were also applicable to the conjugate addition of boron to α,β,γ,δ‐unsaturated carbonyl compounds, although such reactions have previously been very limited in the literature, even in organic solvents. 1,4‐Addition products were obtained in high yields and enantioselectivities in the reactions of acyclic α,β,γ,δ‐unsaturated carbonyl compounds with diboron 2 by using cat. 1, cat. 2, or cat. 3. On the other hand, in the reactions of cyclic α,β,γ,δ‐unsaturated carbonyl compounds with compound 2 , whereas 1,4‐addition products were exclusively obtained by using cat. 2 or cat. 3, 1,6‐addition products were exclusively produced by using cat. 1. Similar unique reactivities and selectivities were also shown in the reactions of cyclic trienones. Finally, the reaction mechanisms of these unique conjugate‐addition reactions in water were investigated and we propose stereochemical models that are supported by X‐ray crystallography and MS (ESI) analysis. Although the role of water has not been completely revealed, water is expected to be effective in the activation of a borylcopper(II) intermediate and a protonation event subsequent to the nucleophilic addition step, thereby leading to overwhelmingly high catalytic turnover.     

Unmodified Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanostructure promoted with external magnetic field: safe,magnetically recoverable,and efficient nanocatalyst for N- and C-alkylation reactions in green conditions

Transition metal compounds have emerged as suitable catalysts for organic reactions. Magnetic compounds as soft Lewis acids can be used as catalysts for organic reactions. In this report, the Fe₃O₄ nanostructures were obtained from Fe²⁺ and Fe³⁺-salts, under an external magnetic field (EMF) without any protective agent. The X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy tools were used to characterize these magnetic compounds. The two-dimensional (2-D, it showed nanometric size in the two dimensions, nanorod structure) Fe₃O₄ compound showed high catalytic activity and stability in N- and C-alkylation reactions. A diverse range of N- and C-alkylation products were obtained in moderate to high yield under green and mild conditions in air. Also the N- and C-alkylation products can be obtained with different selectivity and yield by exposure reactions with EMF. Results of alkylation reactions showed that the presence of Fe(II) and Fe(III) species on the surface of magnetic catalysts (phase structure of magnetic compounds) are essential as very cheap active sites. Also, morphology of magnetic catalysts had influence on their catalytic performances. After the reaction, the catalyst/product(s) separation could be easily achieved with an external magnet and more than 95% of catalyst could be recovered. The catalyst was reused at least four times without any loss of its high catalytic activity for N- and C-alkylation reactions.     

Antioxidative properties of nitroxyl radicals and hydroxyamines in reactions with triplet and deaminated kynurenine

The reactions of triplet kynurenine and 4-(2-aminophenyl)-4-oxocrotonic acid, formed upon the thermal decomposition of kynurenine, with nitroxyl radicals and cyclic N-hydroxylamines were studied. Nitroxyl radicals were found to quench efficiently the triplet state of kynurenine (rate constant 3–6·.10⁸ L mol^-1 s^-1). The quenching proceeds via the spin-exchange mechanism and affords no new products. Neither nitroxyl radicals, nor hydroxyl-lamines react with 4-(2-aminophenyl)-4-oxocrotonic acid under conditions similar to physiological.     

Umsetzungen einiger Schwefel-Fluor-Verbindungen mit Verbindungen von übergangsmetallen; Darstellung und spektroskopische Untersuchung von Sulfito-Komplexen mit MnII,Mo0 und W0

Reactions of some Sulfur-Fluorine Compounds with Compounds of Transition Metals; Synthesis and Spectroscopic Investigation of Sulfito Complexes, involving Mn^II, Mo⁰, and W⁰ In the oxidative addition reactions of sulfuryl fluoride ( 1 ) and of methanesulphonic acid fluoride ( 2 ) with η²-ethylene-bis(triphenylphosphine)platinum(0) the novel ionic binuclear tetrakis(triphenylphosphine)-(μ-fluoro)-(μ-peroxo)-platinum(II)-fluorosulfonate and -methylsulfonate complexes 3 a and 3 b were formed. O,O-Sulfito-manganese(II) tricarbonyl 5 a and the binuclear μ-disulfito-dimanganese decacarbonyl complex 6 a were obtained in the reaction of disulfuryl difluoride ( 4 ) with the carbonyl metalate complex, Na⁺[Mn(CO)₅]^?. In this redox reaction several further products (e.g., CO, SO₂F₂ ( 1 ) and Mn₂(CO)₁₀) were formed and were determined quantitatively. In the presence of acetonitrile the acetonitrile-O,O-sulfito-manganese(II) tricarbonyl complex 5 b was isolated. The new binuclear complexes, bis(η⁵-cyclopentadienyl)-μ-disulfito-dimetalhexacarbonyls ( 6 b : metal = Mo⁰ and 6 c : metal = W⁰) were obtained in the reaction of 4 with the carbonyl metalates Na⁺[CpM(CO)₃]^? (M?Mo¹, W¹; Cp = cyclopentadienyl). Further products (e.g., CO, SO₂F₂ ( 1 ) and [CpM(CO)₃]₂, M?Mo, W) were formed and were determined quantitatively. The validity of the concept of hard and soft acids and bases (HSAB-concept) and of the 18-valence-electron rule (18-VE-rule) could not be confirmed in all cases. The characterization of 3a, 3b, Sb, 6b and 6c was based on their IR and NMR spectra, and in one case, on the mass spectra ( 5b ). For 3a and 3b the dynamic behaviour at room temperature in CD₂Cl₂ and CD₃OD was studied by ³¹P-NMR spectroscopy. The results are interpreted in terms of exchange processes in solution between the coordinated μ-fluoride and the solvent ligand or the uncoordinated anion. 5a and 6a and the by-products (e.g., CO and SO₂F₂ ( l )), which were formed in the redox reactions, were identified by their infrared spectra.     

钌1,2-萘醌-1-肟配合物对aldol C—C成键反应的催化作用

在钌1,2-萘醌-1-肟(1-nqo)配合物cis,cis-[Ru(1-nqo)₂(CO)(NCMe)] (1)或trans,trans-[Ru(1-nqo)₂(PBu₃)₂] (2)的作用下, 氰基乙酸乙酯与取代苯甲醛发生aldol C—C成键反应. 根据GC-MS检测及HPLC分离结果, 对二苯甲醛的二个醛基可分别或同时与氰基乙酸乙酯发生aldol反应. ¹H NMR表征结果证明, 二种产物的双键构型均为反式. 其它取代苯甲醛的反应均给出单一反式aldol产物, 这表明该催化反应具有立体选择性. 配合物1的催化活性稍差, 产率不超过60%, 而配合物2的催化活性要高于1, 最高产率达99%.