| 摘要 |
3-Alkyl-4-amino-5-pyrazolones of the general formula <FORM:0833113/IV (b)/1> wherein R is H, heterocyclic, alkyl, alkyl substituted with carboxyl, ester or nitrile groups, phenyl or phenyl substituted by alkyl, alkoxy, hydroxy, amino, alkylamino, acylamino, carboxyl or sulphonic acid groups, are prepared by converting the 4-unsubstituted compounds into 4-isonitroso compounds, e.g. by dissolving in caustic soda, adding sodium nitrite and adding the mixture dropwise to hydrochloric acid, and then reducing the 4-isonitroso group to an amino group, e.g. with tin and hydrochloric acid, zinc and glacial acetic acid, or with hydrogen under pressure with a nickel catalyst. Examples are given of the treatment of 1-(p-nitrophenyl), 1 - (m - nitrophenyl), 1 - (p-tolyl), 1 - (m - carboxyphenyl), 1 - (m - sulphophenyl) and 1 - (21 - pyridyl) - 3 - methyl - 5 - pyrazolones and 3 - methyl - 5 - pyrazolone to give the 4-isonitroso and 4-amino derivatives. In the case of the 1-(nitro-phenyl) derivatives, the nitro group also becomes reduced to give 1-(aminophenyl) compounds. 1-Phenyl-3-methyl4-iso-nitroso-5-pyrazolone also is reduced with hydrogen under pressure and a nickel catalyst to give 1-phenyl-3-methyl-4-amino-5-pyrazolone. Salts with sulphuric and hydrochloric acids are described. Specifications 459,665, 757,840, 768,071 and 795,476 are referred to. |
