Reaction Of Alkoxides Research Articles

Copolymerization of Epoxides with Cyclic Anhydrides Catalyzed by Tertiary Amines in the Presence of Proton-Donating Compounds

Abstract This paper deals with the copolymerization of epoxide [2-hydroxy-4-(2,3-epoxypropoxy)benzophenone] with cyclic anhydride (phthalic anhydride) catalyzed by tertiary amine (tri-n-hexylamine) in the presence of proton-donating compounds in o-xylene solution at 393°K (120°C). On the basis of kinetic investigations performed in the presence of benzoic acid, a reaction scheme has been put forward for the copolymerization. This scheme involves the assumption that the primary active center of ionic character may arise by interaction of acid with amine as well as by initiation mechanism in the absence of proton-donating compound. In the growth stage, alternating reactions of the carboxylate or alkoxide reaction center with epoxide or anhydride take place to give polyester. The termination involves a mono-molecular decomposition of the active centers giving rise to intermediates with alcoholic and carboxylic terminal groups which participate again in reinitiation of the copolymerization. By comparing the e...

Chiral OS-dialkyl phosphoramidothioates: their preparation, absolute configuration, and stereochemistry of their reactions in acid and base

With amines, the cis- and trans-isomers of 2-chloro-1,3,2-oxazaphospholidine-2-thiones, derived from (–)ephedrine, afford the corresponding 2-amino-derivatives which on sequential treatment with acidic alcohol, sodium hydroxide, and alkyl iodide are converted into OS-dialkyl phosphoramidothioates which are usually enantiomerically pure. In methanolic hydrogen chloride the phosphoramidothioates give the corresponding OS-dialkyl methylphosphorothioates with preponderant inversion of configuration whereas with isopropyl alcohol and hydrogen chloride OS-dialkyl isopropylphosphorothioates are formed with preponderant retention of configuration. With ethanolic hydrogen chloride, whether the P–N bond in the phosphoramidothioates is cleaved with inversion or retention of configuration is a function of the acid strength and of the substituents on nitrogen. Reactions which proceed with retention of configuration proceed by double displacements, initial formation of chloridates being followed by displacements with alcohol. Reactions of alkoxides with OS-dialkyl phosphoramidothioates, irrespective of the degree of substitution on nitrogen, proceed with preponderant inversion of configuration to afford OO-dialkyl phosphoramidates.

Stereochemistry and mechanisms of the reactions of acylsilanes with alkoxides

Using chiral NpPhMeSiCOMe it is shown that the 'cleavage' pathway for the reaction of alkoxides with acylsilanes involves nucleophilic attack at the carbonyl group, followed by subsequent rearrangements which result in optically active NpPhMeSiOR and aldehyde. The 'rearrangement' pathway involves stereospecific migrations of the naphthyl and phenyl groups from silicon to different faces of the adjacent carbonyl group, resulting in chiral naphthylethanol and phenylethanol of opposite absolute configurations.

Oxyhydrative scission of olefins: I. Oxidation of lower olefins

A new type of oxidation of C 2-C 5 olefins leading to the oxidative scissions of carbon skeletons was examined on the V 2O 5-MoO 3 catalyst in the presence of water vapor. Acetic acid and acetaldehyde and acetic acid and propionic acid were selectively formed from C 2-C 4 and C 5 olefins, respectively. The reaction was found to go through consecutive multisteps. Taking into account the similarities between the present oxidation and the oxyhydration reaction, it was concluded that the reaction comprises the oxyhydration of olefins to form ketones and the subsequent oxidative scission of the ketones to acids and aldehydes, thus best being named “oxyhydrative scission.” The reaction scheme was discussed in comparison with mechanisms for other types of olefin oxidation reactions.

KINETIC STUDY OF ALKOXIDE PROMOTED DECOMPOSITION OF ORGANIC PHOSPHONIUM COMPOUNDS Evidence for Hexacovalent Intermediate

Abstract This study reports rate data of the alkoxide promoted decomposition of triphenyl 3-hydroxypropyl phosphonium chloride, diphenyl di(3-hydroxypropyl)phosphonium chloride, and tetraphenyl phosphonium bromide. Comparison of kinetics, rate constants, and activation parameters of the alkoxide promoted decompositions points to different mechanism as compared to the hydroxyl promoted reaction. The alkoxide reaction is believed to proceed via a hexacovalent intermediate. Reasons for the hexacovalent route are discussed.

パラジウム化合物を用いる有機合成反応 Ｉ

Many synthetic reactions with palladium compounds reported after the invention of the Wacker Process are classified into two main groups ; 1. Oxidation reactions with Pd2+ and 2. Catalytic reactions. In this review, the oxidation reactions of olefins, aromatic compounds and other compounds are classified further and they are reviewed with typical examples. Application of the oxidation reactions to organic syntheses are stressed.

Alcoholysis of Medicinally Active 5‐Aminodibenzo[a,d]cycloheptenes

The rate constants for alcoholic solvolysis of the hydrochloride salts of diethylaminodibenzo[a,d]cycloheptene and related amino congeners were determined. The objective was a study of the comparative ease of cleavage of the C—N amino linkage by various aliphatic alcohols. The interaction of protonated amines of this series with alcoholic hydroxyls presumably leads to formation of the corresponding ethers in a manner somewhat analogous to alkoxide reaction with alkyl bromides. The methyl ether produced from solvolysis of diethylaminodibenzocycloheptene hydrochloride was isolated and identified. Methanol appears to react some‐what more rapidly with the amine hydrochlorides than other aliphatic alcohols. The latter produce almost invariant velocity constants with a given amine hydrochloride. The exception was tert‐butanol, which resulted in kobs values about one‐third of those given by the other alcohols. Some velocity constants in formic and acetic acids were evaluated. Generation of carbonium ions of appreciable lifetime was indicated in formic acid by the formation of a highly colored (red‐violet) solution. This color may be a manifestation of the dibenzotropylium ion.

Selenium Catalyzed Synthesis of of Carbonates. The Reaction of Alkoxide with Carbon Monoxide and Oxygen in the Presence of Selenium

Abstract A novel selenium catalyzed synthetic reaction of carbonates was investigated. The reaction of alkoxides with carbon monoxide in the presence of stoichiometric amount of selenium gave carbonates in high yields under atmospheric pressure at 20°C in THF. When the resultant reaction solution was made to react continuously with the mixture gas of carbon monoxide and oxygen, catalytic formation of carbonates was achieved. Isolation of Se-alkyl monoselenocarbonate from the reaction mixture by addition of alkyl halide indicated that carboalkoxy sodium selenide might be formed as an intermediate in the course of present reaction. In connection with these reactions, the reaction of carbonyl selenide with sodium alkoxide in alcohol was also studied.

Photochemical transformations. Part XXXI. Photolysis of thiobenzoic acid O-esters. Part II. General methods for the preparation of thiobenzoic acid O-esters

Treatment of alkoxides with (thiobenzoylthio)acetic acid gives thiobenzoic acid O-esters in high yield. Similarly, the reaction of alkoxides with 2,4-dinitrophenyl dithiobenzoate (IX) gives the corresponding thiobenzoic acid O-ester. Imidate salts react with hydrogen sulphide in pyridine to give thioacid O-esters in good yields.

Preparation and some reactions of alkoxides of gadolinium and erbium

Preparation and some reactions of alkoxides of gadolinium and erbium

Synthesis of substituted pyridines—I : 4,6-dihydroxy-1,3-disubstituted pyridines

The reaction of alkoxides i.e. sodium methoxide and sodium ethoxide with amino-pyranodioxins (I) is a general one and yields 1,3-disubstituted derivatives of 4,6-dihydroxy pyridine. Evidence for the structure of the products was provided by IR and UV spectroscopy. A mechanism for the reaction has been proposed.

Carbonium ions in oxidation reactions of olefins with palladium chloride

Carbonium ions in oxidation reactions of olefins with palladium chloride

Reactions of alkoxides with alkoxysulfonium salts

Reactions of alkoxides with alkoxysulfonium salts

Kinetic Studies in the Chemistry of Rubber and Related Materials. III. Thermochemistry and Mechanisms of Olefin Oxidation

Abstract A new estimate of the O—O bond strength in hydroperoxides is reported, based on a determination of the heats of oxidation of ethyl linoleate and linolenate. This value is employed, together with other known bond strengths and resonance energies, to estimate the heats of a number of alternative oxidation reactions of olefins. By considering the effects of the olefin structure on these heats of reaction, it is possible to see how structural differences can lead to the formation of different oxidation products. The discussion is confined to primary products of the oxidation chain, but, even so, a considerable diversity of behavior is shown to be possible. The final material may include simple monomeric hydroperoxides, polymers with varying amounts of oxygen incorporated in the chain, cyclic peroxides, and scission products. The very limited experimental evidence available falls generally into line with expectation.

Kinetic studies in the chemistry of rubber and related materials. III. Thermochemistry and mechanisms of olefin oxidation

Abstract A new estimate of the O—O bond strength in hydroperoxides is reported, based on a determination of the heats of oxidation of ethyl linoleate and linolenate. This value is employed, together with other known bond strengths and resonance energies, to estimate the heats of a number of alternative oxidation reactions of olefins. By considering the effects of the olefin structure on these heats of reaction, it is possible to see how structural differences can lead to the formation of different oxidation products. The discussion is confined to primary products of the oxidation chain, but, even so, a considerable diversity of behavior is shown to be possible. The final material may include simple monomeric hydroperoxides, polymers with varying amounts of oxygen incorporated in the chain, cyclic peroxides, and scission products. The very limited experimental evidence available falls generally into line with expectation.