Oxidation of Benzyl Halides to Aldehydes and Ketones with Potassium Nitrate Catalyzed by Phase-Transfer Catalyst in Aqueous Media

The catalytic oxidation of benzyl halides to aldehydes and ketones in aqueous media was studied under relatively mild reaction conditions by using phase-transfer catalyst combined with potassium nitrate and 10% aqueous potassium hydroxide solution. As a result, a simple high-yield procedure has been developed.     

Efficient and Mild Iron-Catalyzed Direct Allylation of Benzyl Alcohols and Benzyl Halides with Allyltrimethylsilane

An efficient and mild iron-catalyzed direct allylation of benzyl alcohols and benzyl halides with allyltrimethylsilane has been developed. The present reaction would provide an excellent alternative to published methods because of its excellent yields, sustainable catalyst, and mild conditions.     

Enantioselectivity in Ruthenium-Catalyzed Propargylic Substitution Reactions of Propargylic Alcohols with Acetone: A DFT Study

The enantioselectivity in the propargylic substitution reactions of propargylic alcohols with acetone catalyzed by optically active thiolate-bridged diruthenium complexes was examined via ωB97X-D level DFT calculations. Some structures with intramolecular dispersion interactions between ligands were found for the ruthenium-allenylidene complex, which is the key intermediate in the catalytic reaction, and it was determined that the structure corresponding to the X-ray crystal structure, which had provided the transition state model for the enantioselectivity in previous studies, was not the most stable among the obtained structures. Then, a variety of transition-state structures for the nucleophilic attack of prop-1-ene-2-ol, which is the enol isomer of acetone, on the γ-carbon of the ruthenium-allenylidene complex were explored. Among the transition-state structures with lower energies, the number of structures leading to the major (R) product was found to be larger than that of structures leading to the minor (S) product, providing enantioselectivity in terms of probability distributions. The introduction of a phenyl group in the thiolate ligand was suggested to increase the selectivity. Thus, we propose the novel transition state model for the asymmetric catalytic reaction system.     

Nickel-Catalysed Reactions of Allyl Halides and Related Compounds

Allyl compounds react with carbon monoxide, or with carbon monoxide and acetylene, in the presence of tetracarbonylnickel as catalyst. These catalysts are involved also in coupling reactions and addition reactions of activated olefins and ketones. Reactions of this type can be used for the preparation of unsaturated aliphatic acids, esters, nitriles, hydrocarbons, alicyclic ketones, keto acids, keto esters, diketones, lactones, phenols, and other compounds. The reactions proceed via π-allylnickel complexes.     

Kinetic Studies on Ligand Substitution Reactions of Metallothioneins with DTPA and EDTA

Cd, Zn-thionelns were isolated from the rat liver by improved Winge method and purified further. The composition was determined. The mobilization of Cd ions from the Cd, Zn-metallothioneins was studied with spectrophotometric method. The results show that the reaction of DTP A or EDTA with Cd, Zn-thioneins occurs through three steps. The first step follows pseudo-first order reaction with association mechanism. The formation constants and the dissociation rate constants of the relevant intermediate ternary complexes and apparent rate constants, Kapp were determined. The properties and structure of Cd, Zn-thioneins and ligands with low molecular weights affect the values of Kapp.     

微乳介质中卤代芳烃Ullmann偶联反应

微乳介质中卤代芳烃Ullmann偶联反应;偶联反应;微乳;卤代芳烃     

Kinetic Study of the Catalyzed Substitution Reaction of Benzal Chloride and Sodium Iodide in Acetone

The substitution reaction of benzal chloride (PhCHCl₂) and sodium iodide in acetone needs a metal-ion catalyst. Without considering the effects of solubility and the dissociation of salt, salts of Cr(III), Mn(II), Fe(II, III), Co(II), Ni(II), Cu(II)m Zn(II), Cd(II), Hg(I, II), and Sb(III) ions are used to study their catalytic reactivities. It is found that the Fe(II) ion exhibits acceptable catalytic effect. The overall Fe(II)-catalyzed PhCHCl₂-NaI reaction can be described by the following competitive consecutive scheme: PhCHCl₂ → PhCHCII → PhCHI₂. Under suitable conditions, coupling products such as PhCH=CHPh and PhCHClCHClPh are also found. The rate of the first-stage substitution of the PhCHCl₂-NaI reaction increases linearly with the PhCHCl₂ concentration. It increases asymptotically with the FeCl₂ concentration. However, there is an optimum concentration for Nal. The apparent activation energies are 104 ± 4 kJ/mol and 133 ± 4 kJ/mol for the Fe(II)-catalyzed PhCHCl₂-NaI and PhCHCH-NaI reactions, respectively.     

碱卤晶体中氢氧根的光度测定

本文叙述用单色酸碱指示剂对-硝基酚直接光度测定减卤晶体中OH~-的方法,确定光度测定的条件:吸收峰波长、试剂浓度、稳定性、盐效应等。本法操作简单,灵敏度高(5×10~(-6)wt%)、重现性好(相对偏差<1×10~(-5)wt%),完全适用于碱卤化合物中ppm级以下氢氧根浓度的测定。     

The Behavior of Acid Halides Toward Lewis Acids and Lewis Bases

Reactions of some typical acid halides of carbonic and trithiocarbonic acids and of orthophosphoric and sulfuric acids with Lewis acids and Lewis bases are compared. Acylium, perfluoroacylium, thioacylium, and even sulfonylium ions are obtainable with Lewis acids. It is possible by conductivity measurements and by electronic and above all IR spectroscopic investigations to determine whether the 1:1 adducts of acid halides and Lewis compounds are acylium or sulfonylium salts or donor-acceptor complexes. In the reaction with Lewis bases, the halogen atom in the acid halide is replaced by the electron donor, generally with formation of nonpolar molecular compounds or complexes.     

A Green Procedure for the Oxidation of Benzyl Halides to Aromatic Aldehydes or Ketones in Aqueous Media

Green oxidation of benzyl halides to the corresponding aldehydes or ketones was achieved in aqueous media using trimethylamine N-oxide generated in situ from trimethylamine and H₂O₂. The yield of the reaction was excellent and the workup was simple.     

Kinetic Relationships between Reactions in the Gas Phase and in Solution

Some recent examples of reactions proceeding both in the gas phase and in solution have been investigated to determine their kinetics and mechanisms. The ratio of the corresponding rate constants, k_G and k_L, of the elementary processes studied has been found to be about unity for unimolecular reactions and between 1 and 10 for bimolecular reactions. The mechanisms, overall rates, rate constants, and activation energies have been determined for the homogeneous gas reaction NOCl + Cl₂O = NO₂Cl + Cl₂ and the reaction NOCl + N₂O₅ = NO₂Cl + 2 NO₂, carried out in C₂F₃Cl₃.     

卤离子对化学沉积镍的影响

用重量法测定了卤离子对化学沉积镍速度的影响．并借助电化学方法研究了卤离子对镍的化学沉积过程的极化曲线和稳定电位的影响．探讨了卤离子加速和稳定化学沉积镍的机理     

Palladium‐Catalyzed Carbonylation Reactions of Aryl Halides and Related Compounds

A CO group richer : (Hetero)arenes are vital intermediates in the manufacture of agrochemicals, dyes, pharmaceuticals, and other industrial products. In the past decades transition‐metal‐catalyzed coupling reactions of aryl halides with all types of nucleophiles have been developed. This Review summarizes recent work in the area of palladium‐catalyzed carbonylation reactions of aryl halides and related compounds (see scheme).

     

Spectroscopic Evidence for Ligand Substitution Reactions at the Solid–Liquid Interface of a Sub‐micrometer Gold(I) Carbene Complex

Colloidal coordination compounds in the sub‐micrometer range were synthesized from a chloro gold(I) carbene complex via the anti‐solvent procedure and stabilized by a surfactant shell of Tween 20. This compound was successfully applied as model system to monitor heterogeneous multiphase ligand substitution reactions at the solid–liquid interface.     

Expedient Iron‐Catalyzed Coupling of Alkyl,Benzyl and Allyl Halides with Arylboronic Esters

While attractive, the iron‐catalyzed coupling of arylboron reagents with alkyl halides typically requires expensive or synthetically challenging diphosphine ligands. Herein, we show that primary and secondary alkyl bromides and chlorides, as well as benzyl and allyl halides, can be coupled with arylboronic esters, activated with alkyllithium reagents, by using very simple iron‐based catalysts. The catalysts used were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)₃] with no added co‐ ligands. In the former case, preliminary mechanistic studies highlight the likely involvement of iron(I)–phosphine intermediates.     

Tin(II) Halide Insertion or Halogen Exchange in the Reactions of Dihaloplatinum(II) Complexes with Tin(II) Halide

Reactions of SnCl₂ with the complexes cis‐[PtCl₂(P₂)] (P₂=dppf (1,1′‐bis(diphenylphosphino)ferrocene), dppp (1,3‐bis(diphenylphosphino)propane=1,1′‐(propane‐1,3‐diyl)bis[1,1‐diphenylphosphine]), dppb (1,4‐bis(diphenylphosphino)butane=1,1′‐(butane‐1,4‐diyl)bis[1,1‐diphenylphosphine]), and dpppe (1,5‐bis(diphenylphosphino)pentane=1,1′‐(pentane‐1,5‐diyl)bis[1,1‐diphenylphosphine])) resulted in the insertion of SnCl₂ into the Pt? Cl bond to afford the cis‐[PtCl(SnCl₃)(P₂)] complexes. However, the reaction of the complexes cis‐[PtCl₂(P₂)] (P₂=dppf, dppm (bis(diphenylphosphino)methane=1,1′‐methylenebis[1,1‐diphenylphosphine]), dppe (1,2‐bis(diphenylphosphino)ethane=1,1′‐(ethane‐1,2‐diyl)bis[1,1‐diphenylphosphine]), dppp, dppb, and dpppe; P=Ph₃P and (MeO)₃P) with SnX₂ (X=Br or I) resulted in the halogen exchange to yield the complexes [PtX₂(P₂)]. In contrast, treatment of cis‐[PtBr₂(dppm)] with SnBr₂ resulted in the insertion of SnBr₂ into the Pt? Br bond to form cis‐[Pt(SnBr₃)₂(dppm)], and this product was in equilibrium with the starting complex cis‐[PtBr₂(dppm)]. Moreover, the reaction of cis‐[PtCl₂(dppb)] with a mixture SnCl₂/SnI₂ in a 2 : 1 mol ratio resulted in the formation of cis‐[PtI₂(dppb)] as a consequence of the selective halogen‐exchange reaction. ³¹P‐NMR Data for all complexes are reported, and a correlation between the chemical shifts and the coupling constants was established for mono‐ and bis(trichlorostannyl)platinum complexes. The effect of the alkane chain length of the ligand and Sn^II halide is described.     

Relay-Heck Cross-Coupling Between Alkenyl Halides and Unsaturated Alcohols in the Synthesis of Open-Chain Analogues of Musk Odorant Vulcanolide

Unactivated alkenyl iodides and bromides underwent an unprecedented palladium-catalyzed relay-Heck cross-coupling with a whole range of alkenols of different chain lengths linking the alkene and the alcohol, affording unsaturated aldehydes and ketones in moderate to good yields. In contrast, alkenyl triflates were not suitable partners for this reaction. This method allowed the preparation of open-chain analogues of the musk odorant Vulcanolide, several of which retained key olfactory properties of the parent molecule.     

Sulfenyl Halides in the Synthesis of Heterocycles. 2. Cyclization in Reactions of Hetarenesulfenyl Chlorides with 3,3-Dimethyl-1-butene

Products of additive cyclization with ring closure at the nitrogen atom of the thiohetaryl unit were synthesized by the interaction of 4,6-dimethylpyrimidine-2-, 3-cyano-4,6-dimethylpyridine-2-, quinoline-8-, and 1,3-benzothiazole-2-sulfenyl chlorides with 3,3-dimethyl-1-butene. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, 893–900, June, 2005.