Rhodanilate, ammonium

Many relatively specific reagents, particularly a variety of metal complexes, have been developed as an aid to the isolation of individual amino acids. An example is provided by the isolation of L-proline from a gelatine hydrolysate using the chromium complex ammonium rhodanilate ammonium dianiline-... 

Ammonium salt sesquihydrate, C,sH.lCrN1S4, ammonium rhodanilate. Rose-colored platelets. Sol in methanol. 

Ammonium salt of rhodanilic acid ammonium rhodanilate. 

Isolation. L-Proline is prepared in 15% yield from gelatin by the method of Bergmann (85), (Selatin is hydrolyzed with HCl, ar nine is removed as the flavianate, a methanol solution of ammonium rhodanilate is added to the diluted filtrate, the mixture is cooled, the suspension of proline rhodanilate is filtered, the precipitate is washed and recrystallized from methanol containing 0.5 N HQ, the precipitate is dried and mixed thoroughly with aqueous pyridine, the suspension is filtered, and the filtrate is evaporated in vacuo. The specific rotation (see Table VI) in water, [aJn = —85.6 , is higher than the value, = —80.9 ,... 

About lOOg of pyridine rhodanilate is obtained. To convert this into the ammonium salt for re-use, suspend it in 175 ml of methanol and add 90 ml of concentrated ammonia solution. Stir at 0 °C for 30 minutes and then dilute gradually with 900 ml of water. Filter off the precipitated ammonium salt, wash it with water and repeat the... 

In a later report (106), SubbaRow and Jacobson described briefly the properties of another fraction— fraction F, obtained from fraction B— which appeared to be a polypeptide. It yielded crystalline salts with rhodanilic acid and Reinecke salt. The rhodanilate, showing a positive biuret, diazo and glyoxylic but negative Milton s reactions, ras precipitated by phosphotungstic, picric, rufianic and tannic acids as well as by ammonium sulfate the Reineckate, showing a positive ninhydrin and a weak diazo reaction, was precipitated by phosphotungstic and rufianic acids. Fraction F was inactive in the guinea pig as well as the pernicious anemia patient. 

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