Ruthenium oxychloride

Ruthenium red (ammoniated ruthenium oxychloride) is a strong indicator of the polycarboxylic acid groups in pectin. This reagent is made by adding enough ruthenium red powder to 10% lead acetate to produce a wine-red color. 

Thus, Mathis et al. [1, 2] investigated oxidation reactions with 4-nitroperbenzoic acid, sodium hypobromite, osmium tetroxide and ruthenium tetroxide. Hamann et al. [3] employed phosphorus oxychloride in pyridine for dehydration. However, this method is accompanied by the disadvantages that the volume applied is increased because reagent has been added and that water is sometimes produced in the reaction and has to be removed before the chromatographic separation. 

Oxychlorides.—When ruthenium tetroxide is covered with water, to which caesium chloride acidulated with hydrochloric acid is subsequently added, caesium oxychlor-mthenate,3 Cs2Ru02C14 or 2CsCl.RuOCl2, is formed. On crystallisation dark purple isometric octahedra, cubes, and rhombic dodecahedra separate out. These are soluble in cold hydrochloric acid, from which they may be recrystallised unchanged. 

With concentrated solutions of ruthenium salts, alkali chlorides effect the deposition of violet crystalline precipitates of the double chlorides. These are soluble in water only with difficulty, but are decomposed with boiling water, yielding black insoluble residues of oxychloride. 

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