Hydrolysis of substituted 8-acetoxyquinolines.
In the absence of metal ions, the hydrolysis of 2-methyl-8-acetoxyquinoline and of 5-chloro-8-acetoxyquinoline follow the same reaction paths as those of the parent ester 8-acetoxyquinoline, including an intramolecular catalysis by the quinoline nitrogen. Unlike the hydrolysis of the other esters, that of the 2-methyl compound appears not to be catalysed by metal ions, and this is consistent with the view that catalysis by a metal ion involves the formation of a 7-membered chelate structure.
Determination of beryllium by means of hexamminecobalt(III) carbonatoberyllate—I: Composition of the precipitate and its suitability as a weighing form for beryllium
Abstract The precipitate obtained when hexamminecobalt(III) chloride is added to a solution of beryllium in excess ammonium carbonate has been analysed and its behaviour under different humidity conditions examined. The composition is that of hexamminecobalt(III) hexacarbonato-oxo-tetraberyllate [Co(NH3)6]2[Be4O(CO3)6]·xH2O, as suggested by Sen Gupta, rather than that of Pirtea [Co(NH3)6][(H2O)2 Be2(CO3)2(OH)3]·3H2O.x depends on the humidity of conditioning, varying between 10.8 and 11.1 at relative humidities between 32 and 80%. Drying the precipitate in vacuo over anhydrous magnesium perchlorate or phosphorus pentoxide results in 3 molecules of water being retained. The compound as normally precipitated may be a mixture of the deca- and dodecahydrates that Sen Gupta prepared. After conditioning at a definite humidity and if an empirical factor is used, the precipitate may be suitable as a gravimetric form for determining beryllium where precision requirements are not too exacting.
THE IRON-ACETOCARMINE METHOD OF FIXING AND STAINING CHROMOSOMES
A short description of this procedure was given in Vol. 55 of the American Naturalist, pp. 573â€”574. The method has now been used almost daily for five years, and certain improvements have suggested themselves. The solution can be prepared by mixing about equal volumes of glacial acetic acid and water. To this is added powdered carmine in excess. The liquid is then â€ ? just brought to boil, cooled, and decanted. To the red solution there are then added a few drops of a solution of ferric hydrate in 50 per cent. acetic acid, to act as a mordant. The amount of iron varies with different objects. Too much produces a precipitate in a short time. The more