CH119883A - Process for the preparation of 4-chlorobenzoxazolone-6-arsic acid. - Google Patents

Description

  

  Process for the preparation of 4-chlorobenzoxazolone-6-arsic acid. According to the Swiss procedure. Patents No. 11383 <B> 2 </B>, 114624 and 114625 can be benzoxazolone-5-arsinic acids of the general. Formula 1.
EMI0001.0003
    represent by ni trating benzoxazolones, reducing the resulting nitro compounds and converting the amino derivatives into the corresponding arsinic acids.

   Since the nitro group moves into the p-position to the NH group during the nitration of the benzoxazelones, it is not possible to use the above process to obtain the isomeric benzoxazolone-6-arsinic acids of the formula 1f.
EMI0001.0016
    to win.

      It has now been found that the 4-chloro-6-aminobenzoxazolone obtainable by the action of phosgene on 5-nitro-3-amino-2-oxy-1-chlorobenzene can be reduced by reduction of subsequent diazotization and treatment with arsenites in 4-chlorobenzoxa - Zolon-6-arsic acid can be converted so that, surprisingly, the benzoxazolone ring is retained in all these operations.



  The process leads to a substance which is therapeutically valuable and which is also important as an intermediate for the preparation of other pharmaceutical products. <I> Example </I> I-chloro-G-nitrobenzoxazolone.



  5 Nitro-3-amino-2-oxy-1-chlorobenzene obtained by reducing 132 kg of dinitrochlorophenol with sodium disulfide is dissolved in 500 liters of water and 80 liters of 40 B6 sodium hydroxide solution. Phosgene is introduced into the blood-red solution with the gradual addition of 40 liters of sodium hydroxide solution until the chloronitroaminophenol is consumed. The precipitated clilornitrobenzoxazolone is filtered off with suction and can be immediately subjected to the reduction.



  It dissolves in glacial acetic acid, acetone, ether and alcohol, poorly in hot water, benzene, easily in dilute alkalis, with the formation of the alkali salts, which form yellowish needles. Its melting point is 210-11 C.



       4-Clalo-r-6-aininoben, -oxazolone. 9 kg of 4-Clilor-6-nitrobenzoxazolone are gradually entered into a boiling slurry of 11 kg of iron filings in 40 liters of water and 1.5 liters of 50% acetic acid. When the reduction is complete, the mixture is made up to 80 liters, boiling hot with 2.5 kg of soda made alkaline and suctioned off. The aminomethylbenzoxazolone crystallizes out in weakly colored needles on cooling. It dissolves in hot water, alcohol and acetone, but is almost insoluble in ether and benzene. It dissolves easily in dilute acids and alkalis. Its alkaline solution quickly turns dark.

   Its diazole solution couples bluish red with R salt and orange with resorcinol. 4-Ch lorb eii, zoxa.zolon-6-arsirzsäi cre.



  <B> 4.3 </B> kg of 4-chloro-6-aminobenzoxazolone are mixed with 4 liters of water and 4 liters of 38% hydrochloric acid and 12 kg of ice are added. Then, by adding 2.6 liters of nitrite solution (131 l cm @ = 1000 NN), a.zotiert. For a good i, add 6,4-sodium arsenite and carefully <I> add </I> about 6 kg of soda to make it slightly alkaline. It is stirred until no more diazo compounds can be detected.

   Then it is acidified and suctioned off. After standing for a long time, the arsic acid falls from the filtrate in brown crusts. It can be purified using its sodium salt and then forms white crystals which are easily soluble in alkali, difficult in hot water and not at all soluble in cold water. 4-Clilorbenzoxa.zolon-6-arsinic acid is insoluble in common organic solvents.

 

Claims (1)

PATENT CLAIM Process for the preparation of 4-chloro benzoxa.zolon-6-@irsinsäure, which forms white crystals which are easily soluble in alkalis, difficult in hot water, not soluble in organic solvents and in cold water, characterized in that 4-chloro-6-nitrobenzoxazolone is reduced, the resulting amino compound is diazotized and then treated with alkali arsenite.