Kinetics and mechanism of the Pudovik reaction in the azomethine series: III. Acid-catalyzed hydrophosphorylation of imines

A complex spectral (UV, IR, and ³¹P NMR), preparative, and kinetic investigation of the mechanism of the noncatalytic variant of the Pudovik reaction in the series of imines was carried out. The reaction proceeds through a four-center cyclic transition state. The transition state is highly labile, which determines its high sensitivity to the structure of the reagents, the nature of the solvent and catalyst, and some other factors. The necessary condition for the hydrophosphorylation of imines to occur is the participation of proton-donor reagents and acidic admixtures, specifically hydrolysis products of dialkyl hydrogen phosphites, such as monoalkyl dihydrogen phosphates and phosphorous acid, which act as acid catalysts. When the starting reagents are thoroughly purified and no such catalysts are present, the Pudovik reaction fails to occur in the imine series.     

Formation of a Stable Cationic Hydridodimethylplatinum(IV) Complex by the Reaction of Bis(μ-dimethyl sulfido)tetramethyldiplatinum(II) with Protonated 1,4,7-Triisopropyl-1,4,7-triazacyclononane. A First Example of Oxidative N-H Addition to a Platinum(II) Complex

The complex bis(-dimethyl sulfido)tetramethyldiplatinum(II) reacts with 1,4,7-triisopropyl-1,4,7-triazacyclopropanone (L) over the course of 24 h at room temperature in THF-d ₈ to give [PtMe₂(L)] and PtMe₂(SMe₂)₂. Subsequent addition of 1 mol of trifluoromethanesulfonic acid results in immediate formation of a previously unknown stable cationic complex [PtMe₂H(L)]⁺SO₃CF₃ ^-. This product can also be prepared by oxidative addition of the N-H bond of LH⁺SO₃CF₃ ^- to the starting complex, which points to a higher basicity of the platinum atom in [PtMe₂(L)] compared with the nitrogen atom in the ligand L. The pK _a of the cationic hydride of platinum(IV) was estimated.     

Kinetics and mechanism of triphenylphosphine quarternization with unsaturated carboxylic acids in the medium of acetic acid

Kinetics of reaction of triphenylphosphine with a series of unsaturated carboxylic acids and related esters in the medium of acetic acid as well as in mixtures of acetic acid and acetonitrile was studied by spectrophotometry. The data obtained show that the process of quarternization should be described by kinetic equation of third order, the proton transfer occurs from the solvent. A stepwise mechanism of interaction including formation of prereaction complex on the reaction pathway is proposed.     

Kinetics and Mechanism of the Pudovik Reaction in the Azomethine Series: I. Addition of Dimethyl Hydrogen Phosphite to N-Isopropylbenzalimines

For a series of phenyl-substituted N-isopropylbenzalimines, the effect of substituent on their capability to add dimethyl hydrogen phosphite was studied qualitatively in the condensed phase (DTA) and quantitatively (with determination of the kinetic and activation parameters) in 2-propanol solutions with spectrophotometric monitoring of the reaction. A reaction mechanism was proposed, involving formation of a highly organized four-membered transition state.     

Kinetics and Mechanism of the Pudovik Reaction in the Series of Shiff Bases. Addition of Dialkylphosphites to Substituted N-Alkyl(Aryl)Benzylideneamines

Abstract

Kinetic and preparative investigation of the reaction of addition of dialkylphosphites to a serias of Shiff bases of the type Ar-CH?N-R (R = Alk, Ar₃) (1) is investigated. On the basis of kinetic data obtained (Table) the nucleophilic addition mechanism is suggested.     

Kinetics and Mechanism of the Pudovik Reaction in the Azomethine Series: II.1 Hydrolysis and Catalysis in the Reaction of Dialkyl Phosphites with Benzalaniline

A ³¹P NMR study show that diisopropyl phosphite and benzalaniline do not react with each other as individual components. Adduct formation is made possible by partial hydrolysis of the dialkyl phosphite.     

Kinetics and mechanism of quaternization of tertiary phosphines with unsaturated carboxylic acids. Kinetic studies of the reactions in aprotic solvents

Data obtained while studying the kinetics of quaternization of tertiary phosphines with the unsaturated carboxylic acids in the series of aprotic solvents indicate the participation of a second molecule of acid playing the part of the external proton donor in this process. Quantitative analysis of the effect of solvent within the frames of the Koppel-Palm equation showed that the main contribution in the reaction rate belongs to the nucleophilicity of medium while the effects of polarity and electrophilicity are smaller. The results obtained suggest the step-by-step mechanism of interaction including the formation of the zwitterionic intermediate on the reaction pathway common for the solvents with different proton activity.     

Mechanistic aspects of reactions of triphenylphosphine with electron‐deficient alkenes in acetic acid solution

Kinetic data provide evidence that proton transfer to the carbanion centre of a phosphonium zwitterion is the rate‐determining step in quarternization reactions of triphenylphosphine with electron‐deficient alkenes in acetic acid solution. This conclusion is based on the third‐order rate equation, the reactivity of the alkenes, and solvent isotope effects in deuteroacetic acid. Copyright © 2013 John Wiley & Sons, Ltd.     

Kinetics and Mechanism of the Kabachnic-Fields Reaction

Abstract

The Kabachnic-Fields reaction is one of the most important methods of synthesis of functionally substituted derivatives of tetracoordinated phosphorus with P-C bond. At the same time mechanism of this important and interesting reaction practically has not been investigated.     

Kinetic study of the reaction of triphenylphosphine with acrylic acid in alcohol media

Kinetic study of the reaction of triphenylphosphine with acrylic acid in alcohol media was carried out by spectrophotometric method. Use of alcohols as solvents is shown to introduce a specific feature in the kinetic picture of the reaction due to the appearance of parallel channels of proton transfer: from alcohol and from another molecule of acrylic acid in the solution.