Nitroformaldehyde arylhydrazone

The thermally induced rearrangements in the furoxan series have also been found. In particular, the transformation of 3-R-substituted 4-(3-ethoxycarbonylthioureido)-l,2,5-oxadiazole 2-oxides into derivatives of 5-amino-3-(a-nitroalkyl)-l,2,4-thiadiazole and into (5-amino-l,2,4-thiadiazol-3-yl)nitroformaldehyde arylhydrazones has been reported (Equation 8) <2003MC188>. 

After separation of the insoluble fraction the nitroformaldehyde arylhydrazone was precipitated with dilute hydrochloric acid (0.25 M), Three such cleaning cycles were required to obtain reasonably pure product The reaction yield was 42% bakd on the amine used in the synthesis. Air (tied solid nitroformaldehyde p-naphthylhydrazone is orange and melts at 90-94T. It was characterized by infrared and ultraviolet-visible spectroscopy. 

Figure 4 Conversion of a primary aromatic amine to the corresponding nitroformaldehyde arylhydrazone...

A 0.5 to 10 g-portion of aminopolystyrcne was suspended in a mixture of hydrochloric acid and water cooled to -- -4°C and then diazoUzed with 0.1 mole of Ni 02 dissolved in 40 mL of distilled water. The mixture was stirred for 1 hr to allow complete reaction. The resulting solid was sqiaraled by filtration, washed with edd water to remove an excess of acid, and then immediately transfemed into a cold buff solution of 36 g of sodium acetate, 40 mL of acetic acid, and 20 mL of water. The nitroformaldehyde arylhydrazone (--0.5 to 1 g) dissolved in 200 mL of ethanol was filtered and cooled to 0-2 C. This ethanolic solution was slowly added to the polymer suspension. The final mixture was stirred at -2 to +4 C for 6 hr. The dark colcxed solid was separated and washed with water and then with ethanol until the filtrate was clear. In several cases Soxhlet extraction was used to minimize use of ethanol. 

---