Silver salts, analysis preparation

The silver salts of most carboxylic acids are only sparingly soluble in cold water, and hence are readily prepared. Moreover they very rarely contain water of crystallisation, and therefore when dried can be analysed without further treatment. The analysis itself is simple, rapid and accurate, because gentle ignition of a weighed quantity of the silver salt in a crucible drives off the organic matter, leaving a residue of pure metallic silver. 

Tris(l,10-phenanthroline)iron( n) salts were prepared according to the usual manner. Chloride of [Co(phen)3]3+ was synthesized by refluxing a water-ethanol mixture containing pentaamminechlorocobalt(ni) chloride and 1,10-phenanthroline and by precipitating the salt with an ethanol-acetone mixture the perchlorate was precipitated with sodium perchlorate from the chloride solution. The salts of [Co(bpy>3]3+ were prepared in a similar manner. All the salts were recrystallized and then air-dried their purities were confirmed by the silver titration for the chloride ions, by the visible-ultraviolet spectrum measurement, and by the analysis for the number of water of crystallization,3 of which values were 7.0, 4.7, and 4.0 for the chlorides of [Fe(phen)3]3+, [Co(phen)3]3+, and [Co(bpy)3]3+, respectively, and 0.6, 1.5, and 3.3 for the corresponding perchlorates. 

Preparation of Macromolecular Dioxolenium Salts. Living polystyrene prepared by the polymerization of styrene in THF with a-methylstyrene tetramer dianion reacted with a 2.1-molar amount of ethylene oxide for three hours at room temperature a 6.6-molar amount of adipoyl chloride was added, and the mixture was stirred for 20 horns a 20-molar amount of ethylenebromohydrin was added. This mixture was stirred for 44 hours. The bromoethylated polystyrene was precipitated in excess methanol and freeze-dried from benzene in a vacuum system. A 1-nitropropane solution of polystyrene dioxolenium salt was prepared by reaction of bromoethylated polystyrene with silver perchlorate in 1-nitropropane. Silver bromide was removed from the reaction mixture by filtration. Molecular weight of the product was measured by a vapor-pressure osmometer it was 1910 for living polystyrene and 5190 for the bromoethylated polystyrene. Bromine analysis of the bromoethylated polystyrene showed 67.9% of the calculated value. 

Oxidation of one molar proportion with sodium pieriodate produces two equivalents of formic acid, in accordance with the existence of hydroxyl groups attached to four contiguous carbon atoms. This oxidation (and also that carried out with lead tetraacetate) gives an aldehyde, whose semicar-bazone has an analysis corresponding to that of the semicarbazone of an ethyl formyl-methyl-furoate (XII). By oxidation of aldehyde XII with silver oxide in alkaline solution, 2-methyl-3,4-furandicarboxylic acid (XIV) was obtained this was identical with the compound described by Alder and Rickert.20 The identity was confirmed by preparation of the respective dianilides. The acid XIV has also been prepared by the reaction between the sodium salt of ethyl acetoacetate and ethyl bromopyruvate.9... 

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