Experiments on the synthesis of some coumarin derivatives

1973 ◽  
Vol 26 (4) ◽  
pp. 899 ◽  
Author(s):  
ER Krajniak ◽  
E Ritchie ◽  
WC Taylor
Keyword(s):  
Acetic Acid ◽  
Sulphuric Acid ◽  
Fumaric Acid ◽  
Potassium Acetate ◽  
Coumarin Derivative ◽  
Oxidative Cyclization ◽  
Coumarin Derivatives ◽  
Pechmann Reaction

Evidence has been obtained that the reaction between a phenol and maleic or fumaric acid in the presence of sulphuric acid to yield a coumarin derivative, the Ponndorf reaction, is a variant of the Pechmann reaction. The scopes of the two reactions appear to be similar. ��� Attempts to effect the oxidative cyclization of hydroxyaryl cinnamates to 4-arylcoumarins, a key step in Seshadri's scheme for the biogenesis of neoflavanoids, were unsuccessful. 4-Aryl-3,4- dihydrocoumarins, which are readily available, are smoothly converted into 4-arylcoumarins by iodine and potassium acetate in acetic acid.

Electron Microprobe Analyses of the Remineralization of Enamel

1970 ◽  
Vol 49 (3) ◽  
pp. 621-625 ◽  
Author(s):  
Stephen H.Y. Wei
Keyword(s):  
Acetic Acid ◽  
Electron Microprobe ◽  
Potassium Acetate ◽  
Enamel Surface ◽  
Acetate Buffer ◽  
Demineralized Enamel ◽  
Calcium And Phosphorus

The electron microprobe was used to analyze the calcium and phosphorus concentrations of sound, acid-etched, and remineralized enamel. By use of a weak acetic acid-potassium acetate buffer, it was found that the demineralization probably affected only the first 10 micrometers of the enamel surface. This demineralized enamel was successfully remineralized by the use of a calcifying solution. The changes in calcium and phosphorus concentrations and the Ca/P ratios were determined.

HYDROLYSIS OF CELLULOSE ACETATE SULPHATE IN ACETONE

1954 ◽  
Vol 32 (9) ◽  
pp. 815-822 ◽  
Author(s):  
Karl Keirstead ◽  
John Myers
Keyword(s):  
Acetic Acid ◽  
Cellulose Acetate ◽  
Sulphuric Acid ◽  
Potentiometric Titration ◽  
Titration Method ◽  
Acetate Ester ◽  
Hydrolysis Of Cellulose ◽  
Potentiometric Titration Method ◽  
Hydrolysis Of

When cellulose acetate sulphate is dissolved in acetone the hydrolysis of the sulphate ester is rapid compared with that of the acetate ester. In 70% acetone the relative rates are reversed. Hydrolysis of the sulphate ester in acetone is greatly affected by the temperature. At 25 °C. or greater the hydrolysis is complete after 24 hr. A potentiometric titration method has been developed for the estimation of sulphuric acid in the presence of smaller amounts of acetic acid.

Visible-light promoted oxidative cyclization of cinnamic acid derivatives using xanthone as the photocatalyst

2021 ◽  
Author(s):  
Bin Zhao ◽  
Bo Xu
Keyword(s):  
Double Bond ◽  
Visible Light ◽  
Cinnamic Acid ◽  
Oxidative Cyclization ◽  
Coumarin Derivatives ◽  
Cinnamic Acids ◽  
Cinnamic Acid Derivatives ◽  
Double Bond Isomerization ◽  
Photocatalytic Synthesis

We have developed an efficient photocatalytic synthesis of coumarin derivatives via a tandem double bond isomerization/oxidative cyclization of cinnamic acids.

ChemInform Abstract: Pechmann Reaction in the Synthesis of Coumarin Derivatives

ChemInform ◽  
2015 ◽  
Vol 46 (22) ◽  
pp. no-no
Author(s):  
Majid M. Heravi ◽  
Soheila Khaghaninejad ◽  
Manizhe Mostofi
Keyword(s):  
Coumarin Derivatives ◽  
Pechmann Reaction

STUDIES ON RDX AND RELATED COMPOUNDS: X. ANALYSIS FOR NITRIC ACID IN ACETIC ACID – ACETIC ANHYDRIDE MEDIA

1953 ◽  
Vol 31 (3) ◽  
pp. 214-215 ◽  
Author(s):  
R. A. Marcus ◽  
C. A. Winkler
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Acetic Anhydride ◽  
Analytical Method ◽  
Potassium Acetate ◽  
Standard Solution ◽  
Related Compounds

An analytical method has been developed for the estimation of nitric acid in acetic acid – acetic anhydride media, with a precision of 0.3%. The procedure involves the addition of a solution of potassium acetate in acetic acid to the sample. The excess is back-titrated conductometrically with a standard solution of nitric acid in acetic acid.

On the proteid reaction of Adamkiewicz, with contributions to the chemistry of glyoxylic acid

1901 ◽  
Vol 68 (442-450) ◽  
pp. 21-33 ◽  
Keyword(s):  
Acetic Acid ◽  
Sulphuric Acid ◽  
Glacial Acetic Acid ◽  
Glyoxylic Acid ◽  
Violet Colour

In 1874 Adamkiewicz* described the now familiar reaction which results in the production of a violet colour when strong sulphuric acid is added to the solution of a proteid in glacial acetic acid. Adam­kiewicz did not apparently look upon the employment of the acetic acid as introducing anything beyond a certain modification of the action of sulphuric acid.

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