AT141880B - Process for the preparation of derivatives of 5-aminobarbituric acid. - Google Patents

Description

  

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  Process for the preparation of derivatives of 5-aminobarbiturates.
 EMI1.1
 
 EMI1.2
 
 EMI1.3
 

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 EMI2.1
 



   Example 3: 5 parts by weight of 5-bromo-5-ethylbarbituric acid and 6 parts by weight of p-phenetidine are mixed, solidification immediately taking place with heating. After cooling, it is triturated with dilute hydrochloric acid, washed with alcohol and recrystallized from 90% acetic acid.



  The 5- [p-phenetidino] -5-ethylbarbituric acid thus obtained forms white flakes of F = 244, which are soluble in dilute alkalis, but insoluble in dilute acids.



   Example 4: 30 parts by weight of 5-bromo-1-methyl-5-ethylbarbituric acid (produced by condensation of N-methylurea with ethylmalonic acid diethyl ester and bromination of the 1-methyl-5-ethylbarbituric acid thus obtained in a known manner) are mixed with 21 parts by weight of piperidine in the same way , as described in Example 1, brought to reaction in an absolutely alcoholic solution. The 5-piperidino-1-methyl-5-ethylbarbituric acid thus obtainable melts at 1500. It is easily soluble in ether, acetone, alcohol, chloroform, hot benzene, and very sparingly soluble in petroleum ether and water; on the other hand, it dissolves easily in acids and alkalis.



   If, in the representation of the barbituric acid used, instead of N-methylurea, one starts from other N-mono- or N.N'-dialkyl-, -aryl- or -aralkylureas, or instead of ethylmalonic acid diethyl ester, other alkyl-, aryl- or . Aralkylmalonic acid esters, the correspondingly substituted 5-piperidinobarbituric acids can be obtained in the same way.



   Example 5: 10 parts by weight of 5-bromine-1.3. 5-trimethylbarbituric acid (prepared by condensation of N.N'-dimethylurea with methylmalonic acid diethyl ester and bromination of the 1. 3. 5-trimethylbarbituric acid thus obtained in a known manner) are dissolved in 70 parts by volume of dry benzene and with a solution of 10 parts by weight of piperidine in 30 parts by volume dry benzene is added, with piperidine hydrobromide crystallizing out with warming. The latter is filtered off with suction after cooling, the filtrate is evaporated to dryness in vacuo, the residue is washed with water and recrystallized from 50% alcohol.

   The 5-piperidino-1.3 obtained in this way. 5-trimethylbarbituric acid melts at 108 and forms long white needles that are very difficult to dissolve in water and easily soluble in acids and organic solvents. With caustic soda, the barbituric acid is easily split into the corresponding ureid even in the cold.



   If 7 parts by weight of 5-bromine-1.3 are used in the same way. 5-trimethylbarbituric acid with 5 weight
 EMI2.2
 Addition of alcoholic hydrochloric acid to the hydrochloride of 5-isoamylamino-1. 3. 5-trimethylbarbituric acid is precipitated in white crystals.



   Example 6: 10 parts by weight of 5-bromo-1.3. 5-trimethylbarbituric acid and 10 parts by weight of ethylaniline are slowly heated to 800 on a water bath. After the reaction has subsided, which manifests itself through spontaneous heating to 1000 and the color change from brown to green, it is cooled, taken up with alcohol and stirred into very dilute hydrochloric acid. The 5- [N-phenyl-N-äthyIamino] -1 precipitated in this way. 3. 5-trimethylbarbituric acid melts at 108 after recrystallization from 50% alcohol.

 

Claims (1)

PATENT CLAIM: Process for the preparation of derivatives of 5-aminobarbituric acid of the general formula: EMI2.3 (where RI and RU are hydrogen or any monovalent hydrocarbon radicals, RIII is just such a WV is hydrogen or an alkyl radical, RV is any monovalent organic radical, or WV and Rv together are a cyclic radical), characterized in that 5-monohalogenated 5 -Alkyl, 5-aryl or 5-aralkyl barbituric acids in the absence of water, if appropriate in the presence of organic solvents, with primary or secondary amines, with the exception of secondary aliphatic amines.