Molecular dynamics method is applied to study the structure of stable sulfuric acid–water clusters at various compositions. Also a planar liquid–vapor interface is studied. Two different potential models were used. In the simpler model, sulfuric acid (H 2 SO 4 ) remains in an undissociated state. A more realistic scheme requires that in the presence of water (H 2 O) H 2 SO 4 protonates to form ...

Camptothecin-20-propinate (CZ48) and other camptothecin ester derivatives were prepared by the esterification reactions of camptothecin or 9-nitrocamptothecin with the corresponding acylating agents such as organic acid anhydride or chloride with concentrate sulfuric acid as the catalyst. The sulfuric acid-catalyzed reactions gave high yields of camptothecin ester products.Among the 11 compound...

The problem of estimating quantitatively the components of a mixture of naturally occurring estrogens has been attacked through the preparation of their p-phenylazobenzoyl (azoyl) esters and separating these esters by the chromatographic adsorption technique (1). By this method, the monoazoates were quantitatively separated from the diazoates. Hydrolysis of these esters and suitable extraction ...

A practical and green method for the synthesis of 5H-dibenzo[b,i]xanthene-tetraones and spiro[dibenzo[b,i]xanthene-13,3'-indoline]-pentaones by the condensation of 2-hydroxynaphthalene-1,4-dione with aldehydes or isatins, respectively, in the presence of a catalytic amount of cellulose sulfuric acid (CSA) under solvent-free conditions at 100 °C is described. The significant features of this pro...

Ammonium molybdate, in acid solution, is reduced to an oxide stage, with the production of a blue color, by many substances of biological importance. Our attention was first attracted to this subject through an accidental observation. We were engaged in the attempt to work out a technique for the nephelometric estimation of phosphoric acid, using a heavy solution of cane sugar for the medium of...

(1) If heated with iodine as a catalyst, the tertiary alcohol (I) readily yielded the olefin (III). (2) This olefin rearranged immediately to the dicyclic hydrocarbon (II) when digested with concentrated sulfuric acid. (3) Treated with the proper concentration of sulfuric acid, or phosphoric acid, the alcohol (I) passed immediately to the olefin (III), which on longer treatment changed to the i...

Treatment of deactivated aromatic compounds with Nbromosuccinimide in trifluoroacetic acid solvent in the presence of sulfuric acid gave the corresponding monobromoaromatic compounds in good to excellent yields.

The distribution of charged species produced by electrospray of an ammonium sulfate solution in both positive and negative polarities is examined using Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Positively-charged ammonium bisulfate cluster composition differs significantly from negatively-charged cluster composition. For positively-charged clusters all sulfuric acid...

The classical procedure for the preparation of homocystine consists of boiling a solution of methionine in 50 per cent sulfuric acid followed by neutralization (1). Although the yields of homocystine account for only 25 to 45 per cent of the methionine, the nature of the reaction has received little attention since originally published by Butz and du Vigneaud (1). These authors noted the format...