948 REPORTS ON THE STATE OF SCIENCE, ETC. 
and up to 150°C. in the dry state. This salt, which retains its diazo nitrogen and 
coupling power for an indefinite time, gives rise to sparingly soluble diazonium 
platinichloride and aurichloride.' Other 4-aminopyrazole derivatives yield similarly 
stable diazo-derivatives.? 
When the diazonium group is in position 5 the product is distinctly less stable, for 
1-Phenyl-3-methyl-4-ethylpyrazole-5-diazonium chloride decomposes at room tem- 
perature in a few hours, and quickly on warming.’ 1-Phenyl-3-methyl-5-aminopyrazole I 
containing a labile hydrogen atom in position 4 gives only 12 per cent. of diazonium 
compound.® 
C,H, N—_CN,Cl 
3 | Nox 
C,H, N—C—NH, ‘HC! .., N—C-CH, 
Sou 
—C-CH, seas C,H, N——_ C:NH 
=e ee 
; | Se: Now 
N—C-OH, 
Substitttion of the labile hydrogen by an alkyl group prevents the second reaction, 
and diazotisation takes place quantitatively. 
In the case of 1-Pheny]l-3-methyl-4-amino-5-anilinopyrazole an azimino compound 
IT is formed unless diazotisation is carried out in strong acid.‘ 
N—c-CH, Nee 
Sonu, + HONO | pe -N 
C,H,-N—_¢—_NH — > on n_c/_y>N4 28,0 
ak 
C,H; C,H, 
II 
On adding a solution of any diazonium salt of the general formula III to boiling 
dilute sulphuric acid the diazonium nitrogen is retained and a triazine IV is produced. 
CH,C__ CR CH,-C__C-R 
| Sons HS0, avs, | Don :N+H,80 
N-——N°‘C,H, N__% Liane 
rae Ty ae 
R=an alkyl group. 
In this series replacement of the diazonium complex by iodine® and by the 
triazo group has been effected. It is noteworthy that 4-triazo-3 : 5-dimethylpyrazole V, 
a well-defined crystallisable compound, has the remarkable property of giving 
distinctive colour reactions with all phenolic substances not containing nitro-groups. 
NH——C-CH, NH—C:CH, 
S fode toe Na 
ge 2 ras | PP N; 
N——C:CH, N—C:CH, 
Vv ° 
' Morgan & Reilly, 7. 1914, 105, 435. ?Knorr, B. 1895, 28, 717; Michaelis & 
Schafer, A. 1915, 407, 229; Michaelis & Bressel, A. 1915, 407, 274. *% Mohr, 
J. Pr. Chem. 1914, 90, (ii) 509. + Michaelis & Schafer, loc. cit. * Knorr, loc. cit. 
Pyrazoltone Series. 
Very stable salts are obtained on diazotising the hydrochlorides of the amino- 
pyrazolones ; the products are crystallisable from hot aqueous solutions, and are stable 
in a dry state for an indefinite time.'! The acid diazonium salts, VI, from amino 
antipyrine? are exceptionally stable and re-crystallisable and in these respects are 
