PROCEDIMIENTO PARA LA OBTENCION DE UREAS PURAS, ASIMETRICAMENTE DISUBSTITUIDAS

METODO PARA LA OBTENCION DE UREAS DISUBSTITUIDAS ASIMETRICAMENTE DE LA FORMULA GENERAL EN LA QUE R REPRESENTA UN RESTO DE FENILO NO SUBSTITUIDO O SUBSTITUIDO SIMPLE O MULTIPLEMENTE POR ATOMOS DE HALOGENO O GRUPOS DE ALCOILO, ALCOXI, ARILOXI O TRIFLUORMETILO, UN RESTO DE OXAZOLIL, ISOXAZOLIL, TIAZOLIL, ISOTIAZOLIL, BENZOXAZOLIL O BENZTIAZOLIL UNSUBSTITUIDO O SUBTITUIDO SIMPLE O MULTIPLEMENTE POR ATOMOS DE HALOGENOS O GRUPOS DE ALCOILO, ALCOXI, ARILOXI O TRIFLUORMETILO Y R SUB 1 Y R SUB 2 INDEPENDIENTEMENTE UNA DE OTRA REPRESENTAN UN ATOMO DE HIDROGENO O UN GRUPO ALCOILO, EN EL QUE R SUB 1 Y R SUB 2 NO SON SIMULTANEAMENTE HIDROGENO, O R SUB 1 Y R SUB 2 CONJUNTAMENTE REPRESENTAN UN GRUPO DE BUTILENO O DE PENTILENO, POR LA TRANSFORMACION DE UNA UREA N-ALCOILO O N, N-DIALCOILO CON UNA IGUALMENTE SUSTITUIDA ARILOAMINA O UNA AMINA HETEROCICLICA CON PRESENCIA DE AQUELLA AMINA QUE YA CONTENIA EL PRODUCTO DE PARTIDA, YA FUESE N-ALCOILO O UREA N, N-DIALCOILO. Process for the preparation of pure, unsymmetrically disubstituted ureas of the general formula I in which R denotes a phenyl radical which is unsubstituted, or monosubstituted or polysubstituted by halogen atoms or alkyl, alkoxy, aryloxy or trifluoromethyl groups, an oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, benzoxazolyl or benzothiazolyl radical which is unsubstituted, or monosubstituted or polysubstituted by halogen atoms or alkyl, alkoxy or trifluoromethyl groups and R1 and R2 independently of one another denote a hydrogen atom or an alkyl group, where R1 and R2 are not simultaneously hydrogen or R1 and R2 together denote a butylene or pentylene group, by reaction of an N-alkyl- or N,N-dialkylurea with an unsubstituted or substituted arylamine or a heterocyclic amine in the presence of that amine which is already present in the starting material, the respective N-alkyl- or N,N-dialkylurea.