5-Amino-3-methyl-1,2,4-thiadiazole → 3-Methyl-5-nitrosoamino-1,2,4-thiadiazole

First, 11.5 g (0.1 mol) of 5-amino-3-methyl-1,2,4-thiadiazole was dissolved in 100 mL of 2N sulfuric acid. While the mixture was stirred, an aqueous sodium nitrite solution (containing 8.0 g (0.116 mmol) of sodium nitrite in 20 mL of water) was added dropwise to the mixture at 0° C. or less. After completion of dropwise addition, the resultant solution was continuously stirred further for one hour at 0° C. The crystals precipitated were collected by filtration and washed with ice cold water. The crystals were dried in the air at room temperature overnight to obtain 8.5 g (56% in yield) of 3-methyl-5-nitrosoamino-1,2,4-thiadiazole. Next, 7.2 g (0.05 mol) of the obtained thiadiazole was dissolved in 50 mL of methanol at room temperature. While the resultant solution was stirred, 3 mL of concentrated sulfuric acid was added dropwise to the solution at 5° C. or less. After completion of dropwise addition, the solution was continuously stirred further at 5° C. or less for one hour or less and at 15 to 20° C. for 2 hours. The crystals precipitated were collected by filtration. The crystals were recrystallized from methanol to obtain 2.5 g (41% in yield) of triazene dissociative direct dye D-5.

1. additionAfter completion of dropwise addition
2. customThe crystals precipitated
3. filtrationwere collected by filtration
4. washwashed with ice cold water
5. customThe crystals were dried in the air at room temperature overnight

ORD record

ord-ea830dab658b4816904ecc7e8972ac0a

Source dataset

uspto-grants-2010_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07824449B2