Spectrophotometric investigation of beryllium-2-hydroxy chalcone complex

2′-Hydroxy chalcone gave an intense orange-yellow color with beryllium in the pH range 5·5–6·2. The limits of identification and dilution were 0·125γ and 1:4 × 10⁵ respectively. A detailed spectro-photometric investigation of the color reaction was carried out. The complex obeyed Beer’s Law in the concentration range of 0·5–6·0p.p.m. at 460 nm. In the complex the ratio of metal to ligand is 1:2. The instability constant of the complex was 2·176 × 10^?6 at 28°. Oxalate, tartrate, citrate and fluoride interfered. The tolerance limits of iron, aluminium, chromium, uranium, thorium and vanadium are reported.     

Oxidation ofα-hydroxy acids and derivatives by Cr(VI) oxide

The kinetics of the chromic acid oxidation ofα-hydroxy acids, their salts and esters has been investigated in binary solvent mixtures of acetic acid and water. The results indicate that the Westheimer hypothesis of a rate-determining proton-abstraction from a preformed chromate ester is unlikely. Substituent and salt effects indicate the likelihood of a mechanism involving a rate-determining hydride ion abstraction assisted by a proximate substituent.     

Flavylium salts containing pyrone rings

Proceedings - Mathematical Sciences - Flavylium salts containing γ- and α-pyrone rings have been prepared by condensing 7-hydroxy-3-methoxy-flavone-8-aldehyde and umbelliferone-8-aldehyde...     

Pyrilium salts derived from 4-O-methyl resorcylic aldehyde

Proceedings - Mathematical Sciences - 4-O-methyl ether of resorcylic aldehyde has been condensed with (I) acetophenone, (II) ω: 4-dihydroxy acetophenone, (III)...     

Perfect graphs with noP 5 and noK 5

We prove that Berge’s Strong Perfect Graph Conjecture is true for graphs with no induced path on five vertices and no clique of size five.