Markush was awarded a patent from the US Patent Office for " Pyrazolone Dye and Process of Making the Same " on August 26, 1924.
2.
It has a molecular formula of C 3 H 4 N 2 O . There are three possible isomers : 3-pyrazolone, 4-pyrazolone, and 5-pyrazolone.
3.
It has a molecular formula of C 3 H 4 N 2 O . There are three possible isomers : 3-pyrazolone, 4-pyrazolone, and 5-pyrazolone.
4.
It has a molecular formula of C 3 H 4 N 2 O . There are three possible isomers : 3-pyrazolone, 4-pyrazolone, and 5-pyrazolone.
5.
In U . S . P . # 5, 096, 801 Koya " et al . ", of Fuji Photo Film company, list some 150-200 chemical structures, mainly azo dyes and pyrazolone-diazenyl, but fail to provide chemical names, CAS Registry numbers, or Colour Index numbers.