DE923192C - Process for the preparation of N-aryl-pseudothiohydantoins - Google Patents

Description

Process for the production of N2-aryl-pseudothiohydantoins The production of i \ T2-aryl-pseudothiohydantoins has so far been carried out in principle by three methods: Either the corresponding arylthioureas were reacted with chloroacetic acid, its esters or acid halides, or chloroacet-arylamides were combined with r'hodane salts or thiourea for the reaction, whereby in some cases the 3-aryl-pseudothiohydantoins are formed first, which are then rearranged, optionally directly in the reaction mixture, to the N2-aryl isomers. Finally, thioglycolic acid has also been condensed with aryl cyanamides to give the N2 aryl pseudothiohydantoins. (See Beilstein's Handbook of Organic Chemistry, 4th ed., Vol. A7, pp. 2.35 ff .; z. Supplementary work, Vol. 27, p.304.) These processes have the disadvantage that they use arylthioureas as starting materials or the also not easily accessible and unstable arylcyanamides need.

The representation of the N2-aryl-pseudothiohydantoins, starting from of the chloroacet-arylamides, is also cumbersome; it is also uncomfortable that when refluxing the N-arylchloroacetamides with potassium rhodanide in Alcohol frequently poking through the deposited potassium chloride occurs.

It has now been found that, starting from the pseudothiohydantoin, which is easily accessible from chloroacetic ester and thiourea, the N2-aryl-pseudothiohydantoins can be obtained by heating with optionally substituted aromatic amines with escape of ammonia, which is expediently in a solvent , such as water, alcohol, or a mixed solvent works. The conversion takes place according to the reaction equation In the above formulas, Ar denotes an aromatic radical which is optionally substituted in the nucleus.

The resulting products are valuable intermediates for dyes and photographic sensitizers and have sedative and anticonvulsant properties.

Example s 11.6g of pseudothiohydantoin are used in the necessary amount Dissolved hot water, the solution is mixed with 9.5 g of aniline and in a stream of nitrogen heated under reflux for 10 hours. Crystals separate out, which are filtered off, washed with ether and recrystallized several times from methanol. The received N2-phenyl-pseudothiohydantoin with a temperature of 178 ° (3 g corresponding to 16.5%) gives with a Sample of an N2-phenylpseudothiohydantoin made from chloroacetic acid and phenylthiourea no melting point depression.

Example e 11.6 g of pseudothiohydantoin and 12.8 g of m-chlorosniline are used dissolved in a mixture of 18o cc water and 5o cc isopropyl alcohol and 3 to Heated under reflux for 4 days. After cooling, the deposited crystal cake becomes purified by recrystallization from benzene and glacial acetic acid. The crude product is obtained in a yield of 44%. The recrystallized N2-m-chlorophenyl-pseudothiohydantoin melts at 18o '°.

Example 3 I 1.6 g of pseudothiohydantoin are mixed with I 2.85 g of p-toluidine in aqueous isopropyl alcoholic solution until the ammonia development ceases, that's about 3 days, heated to reflux. After distilling off the water the residue is recrystallized from benzene. 4.5 g are obtained (corresponding to 21.6%) N2-p-tolyl-pseudothiohydantoin; F. 1821.

Claims (1)

PATENT CLAIM: Process for the preparation of N2-Arylpseudothiohydantoinen of the general formula wherein Ar denotes an optionally substituted aryl group, characterized in that pseudothiohydantoin is reacted with an optionally substituted arylamine at an elevated temperature, optionally in the presence of a solvent.