Acid In Aprotic Solvents Research Articles

Linoleate hydroperoxides are cleaved heterolytically into aldehydes by a Lewis acid in aprotic solvent.

Treatment of isomeric methyl linoleate hydroperoxides with a Lewis acid, BF3, in anhydrous ether led to a carbon-to-oxygen rearrangement that caused cleavage into shorter-chain aldehydes. Methyl (9Z,11E)-13-hydroperoxy-9,11-octadecadienoate afforded mainly hexanal and methyl (E)-12-oxo-10-dodecenoate, whereas methyl (10E,12Z)-9-hydroperoxy-10,12-octadecadienoate cleaved into 2-nonenal and methyl 9-oxononanoate. The 2 aldehydes obtained from each hydroperoxide isomer were uncharacteristic of the complex volatile profile usually obtained by β-scission of oxy radicals derived from homolysis of the hydroperoxide group. Rather, the reaction resembled the one catalyzed by the plant enzyme, hydroperoxide lyase.

Kinetics of the isomerization reaction of cholest‐5‐en‐3‐one catalyzed by trichloroacetic acid in aprotic solvents of low dielectric constant

AbstractThe isomerization reaction of cholest‐5‐en‐3‐one has been studied in a solution of cyclohexane using trichloroacetic acid as catalyst. At the same time a general reaction scheme is proposed to be valid for all the cases assayed in which the monomer form of the acid is considered as the only effective catalyst. The experimental results agree with these hypotheses and with the calculation of the individual rate constant together with the reaction order with respect to the catalyst. Semiquantitative studies have been carried out with other catalysts and solvents, confirming the validity of the reaction scheme. The thermodynamic activation parameters have also been calculated, and a comparative study was made with the results of the evaluation of the reaction when it takes place in amphiprotic solvents. A reaction mechanism is proposed based on all the kinetic information obtained.

Cleavage direction of C-O bond in anion radicals of methyl esters of aromatic acids in aprotic solvents

Cleavage direction of C-O bond in anion radicals of methyl esters of aromatic acids in aprotic solvents

A new type of acid-induced intramolecular cyclisation of Knoevenagel condensation products in the carbohydrate field. Stereochemical control of the cyclisation process.

The products of the Knoevenagel reaction between methyl acetoacetate and aldehydopentoses undergo various cyclisation processes when treated with trifluoroacetic acid in aprotic solvents which are controlled by the sugar configuration at C-2 and C-3.

PREPARATION OF 6-THIA-3,8-DIAZABICYCLO/3,2,1/OCTAN-2-ONES

Abstract Study of the isomerisation of penilloic acid in aprotic solvents revealed the epimerisation at position C-4, when opening of thiazolidine ring was prevented by N-acetyl group(I).

Dansylation of amines, phenolic and catecholic amines and amino acids in aprotic solvents

Dansylation of amines, phenolic and catecholic amines and amino acids in aprotic solvents

ChemInform Abstract: SYNTHESIS OF SUBSTITUTED 6H-1,3-THIAZINES

Substituted 4,5-dihydro-4-hydroxy-6H-1,3-thiazines II can be prepared in high yields from the BF3 etherate-catalysed reaction between α,β-unsaturated aldehydes, ketones and ketols on the one hand and thioamides, thioureas and dithiocarbamates on the other. In some instances these dihydrohydroxythiazines can be converted into the corresponding 6H-1,3-thiazines III with POCl3 in pyridine or with acid in aprotic solvents. The conditions of this elimination reaction are discussed.

Synthesis of substituted 6H‐1,3‐thiazines

AbstractSubstituted 4,5‐dihydro‐4‐hydroxy‐6H‐1,3‐thiazines II can be prepared in high yields from the BF3 etherate‐catalysed reaction between α,β‐unsaturated aldehydes, ketones and ketols on the one hand and thioamides, thioureas and dithiocarbamates on the other.In some instances these dihydrohydroxythiazines can be converted into the corresponding 6H‐1,3‐thiazines III with POCl3 in pyridine or with acid in aprotic solvents. The conditions of this elimination reaction are discussed.

Periodic Acid, a Novel Oxidant of Polycyclic, Aromatic Hydrocarbons.

Certain polycyclic, aromatic hydrocarbons can be oxidized with periodic acid in aprotic solvents containing a small proportion of water. A unique, two-fold character of response to periodic acid by these hydrocarbons has been found: (1) production of a coupling reaction through a radical intermediate [conversion of pyrene into 1,1'-bipyrene, and fluorene into 1,2-bis(2,2'-biphenylylene)ethylene] or (2) conversion into quinones by a two-equivalent oxidation mechanism that does not involve a radical intermediate [acenaphthene, anthracene, anthrone, benz[a]anthracene, naphthacene, naphthalene, and phenanthrene]. Little or no reaction was observed when oxidation was attempted with sodium metaperiodate instead of periodic acid. Electron-spin resonance revealed no radical intermediate in the oxidation of malonic acid with either periodic acid or sodium periodate.

Periodic acid, a novel oxidant of polycyclic aromatic hydrocarbons

Certain polycyclic, aromatic hydrocarbons can be oxidized with periodic acid in aprotic solvents containing a small proportion of water. A unique, two-fold character of response to periodic acid by these hydrocarbons has been found: (1) production of a coupling reaction through a radical intermediate [conversion of pyrene into 1,1'-bipyrene, and fluorene into 1,2-bis(2,2'-biphenylylene)ethylene] or (2) conversion into quinones by a two-equivalent oxidation mechanism that does not involve a radical intermediate [acenaphthene, anthracene, anthrone, benz[a]anthracene, naphthacene, naphthalene, and phenanthrene]. Little or no reaction was observed when oxidation was attempted with sodium metaperiodate instead of periodic acid. Electron-spin resonance revealed no radical intermediate in the oxidation of malonic acid with either periodic acid or sodium periodate.

OXIDATION WITH NICKEL PEROXIDE. 3. OXIDATIVE CLEAVAGE OF ALPHA-GLYCOLS, ALPHA-HYDROXY ACIDS, ALPHA-KETO ALCOHOLS, AND ALPHA-KETO ACIDS.

Solid nickel peroxide, readily obtainable by the treatment of nickel salts with sodium hypochlorite in alkaline solution, has been proved to be an useful reagent for the oxidative cleavage of α-glycols and α-hydroxy acids in aprotic solvents. Some kinds of aldehydes or ketones were obtained in moderately good yield as glycol cleavage products. With nickel peroxide in an aqueous alkaline solution, α-keto alcohols and α-keto acids were transformed into carboxylic acids by the oxidative cleavage.

The Inversion of Menthone with Trichloroacetic Acid in Aprotic Solvents

The Inversion of Menthone with Trichloroacetic Acid in Aprotic Solvents