Rubazonic acids

Disposition in the Body. Absorbed after oral administration. It is rapidly and extensively metabolised. About 30 to 50% of a dose is excreted in the urine in 3 days as 4-aminophenazone and its acetyl derivative 4-acetamidophenazone which is the major urinary metabolite other metabolites found in the urine include two red pigments, rubazonic acid and methylrubazonic acid dimethylnitrosamine may be formed in the stomach. Less than 5% of a dose is excreted in the urine unchanged. 

Rubazonic acid, 338 Rubbing alcohol, 593 Rubelix, 898 Rubesol, 496 Rubesol-LA, 669 Rubion, 496... 

The 4-amino-2-pyrazolin-5-ones react as do other amines. They can be alkylated with alkyl halides992 and react with aldehydes to form Schiff bases.633"2 Oxidation of these amino compounds with ferric chloride leads to the rubazonic acids (eq. 178) in which two 2-pyrazolin-... 

Rubazonic acid itself is 4-(3-methyl-l-phenyl-5-oxo-2-pyrazolin-4-ylideneamino)-3-methyl-l-phenyl-2-pyrazolin-5-one. 4-Arylimino-2-pyrazolin-5-ones are readily reduced to the corresponding 4-arylamino-2-pyrazolin-5-ones.1538 2-Pyrazolin-5-ones react with 4-arylimino-2-pyrazolin-5-ones to give bispyrazolinones (eq. 179).1538... 

The methylation of 4-arylazo-2-pyrazolin-5-ones has already been mentioned.52 Nitration occurs with replacement of the 4-arylazo group.262 Reduction occurs readily but two different paths are followed. As mentioned earlier, 4-amino-2-pyrazolin-5-ones can be obtained by catalytic reduction670 and with zinc and hydrochloric acid.397 However, reduction with zinc and acetic acid leads to rubazonic acids (eq. 189). 

Only half-a-dozen of these compounds are known (Table XLI) and at least this number of methods of preparing them have been reported. Borsche and Manteuffel125 have found that 2-pyrazolin-4,5-diones are formed as the by-products when oc-ketoesters are treated with aryl-diazonium salts. The principal products are 4-arylazo-2-pyrazolin-5-ones. Nitric acid oxidation of 3-methyl-l-phenyl-2-pyrazolin-5-one forms the corresponding 4,5-dione.809 Wislicenus and Gtiz1842 heated 4 -bromo - 4 - nitro -1 - (4 - bromophenyl) - 3 - methyl - 2 -pyrazolin - 5 - one in water and obtained the analogous 4-oxo compound. Acid hydrolysis of rubazonic acids, which are 4-imino-2-pyrazolin-5-ones, leads to 2-pyrazolin-4,5-diones.424 809 Oxidation of 4,4 -bis(2-pyrazolin-5-ones) or of rubazonic acids with nitric acid809 forms the 4,5-diones. 

A small amount of a complex of 4-hydroxyantipyrine with glucuronic acid can be isolated from the urine after ingestion of pyramidone (138). The main products of pyramidone metabolism in man are 4-acetylamino-antipyrine and 4-aminoantipyrine and these two compounds account for about 50 per cent of a 0.5 g. dose. Isolation of a glucuronoside of unknown constitution also was reported by Jaffe (184). In addition the latter investigator isolated rubazonic acid (LXVII) (184) and antipyrylurea (LXVIII) (185). These latter two compounds may have been artifacts (447). 

Resacetophenone, 55 Resorcinol, 41 4-amino-, 57 4-chloro-, 42 Rice factor, 20 Rivanol, 65 Rubazonic acid, 67... 

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