The synthesis was conducted in water/THF, at 5°~8°C from hydrazine and sulphonyl chloride. The last was added drop by drop to avoid the formation of dimer, in theory.
Hi Micael,
I have done this orgsyn procedure, and it works very well. It is important to use excess hydrazine. You can deposit the aqueous extract directly into bleach if you are at all worried about hydrazine.
o-Nitrobenzenesulfonyl hydrazide (NBSH) was prepared as follows: Hydrazine monohydrate (12.1 mL, 0.25 mol, 2.5 equiv) is added dropwise to a solution of o-nitrobenzenesulfonyl chloride (22.2 g, 0.10 mol, 1 equiv) in THF (100 mL) at −30°C under an argon atmosphere. During the addition the reaction mixture becomes brown and a white precipitate of hydrazine hydrochloride is deposited. After
stirring at −30°C for 30 min, thin-layer chromatographic (TLC) analysis indicates that the sulfonyl chloride has been consumed (2:1 ethyl acetate-hexanes eluent). Ethyl acetate (200 mL, 23°C) is added to the cold reaction solution, and the mixture is washed repeatedly with ice-cold aqueous 10% sodium chloride solution (5 × 150 mL); each wash involved a contact time of ≤ 1 min. The organic layer is dried over sodium sulfate at 0°C, then added slowly to a stirring solution of hexanes (1.2 L) at 23°C over 5 min. o-Nitrobenzenesulfonyl hydrazide precipitates within 10 min as an off-white solid and is collected by vacuum filtration. The filter cake is washed with hexanes (2 × 50 mL, 23°C), and dried under reduced pressure (< 1.5 mm) at 23°C for 14 hr to afford pure NBSH as an off-white powder (17.6 g, 81%); mp 100-101°C; IR (EtOAc) cm−1: 3100-3400, 1547, 1352, 1165 ; 1H NMR (300 MHz, CD3CN)
δ: 3.90 (bs, 2 H), 5.97 (bs, 1 H), 7.78-7.91 (m, 3 H), 8.03-8.17 (m, 1 H) ; 13C NMR (75 MHz, CD3CN) δ: 125.8, 130.8, 133.2, 133.4, 135.5, 149.4 . Anal. Calcd for C6H7N3O4S: C, 33.18; H, 3.25; N, 19.35. Found: C, 33.41; H, 3.27; N, 19.20; Rf
= 0.19 (2:1 ethyl acetate-hexanes). Because solutions of NBSH are unstable at room temperature, the solution of NBSH in tetrahydrofuran should be prepared just prior to addition to the reaction mixture.
To synthesize sulphonyl-hydrazides use methyl ester of sulphonic acid then react with hydrazine at 45 deg. temperature in methanol for 0.5 hrs. on cooling you will get solid hydrazide.
The first metodology have to be improved if a solution of sulfonylcloride would be slovly added to a large excess of Hydrazine monohydrate. In this case dimer formation is minimised. If the vice verta addition as it described in answer #1, dimer formation is possible because first drops of Hydrazine monohydrate would be added to an excess of sulfuril cloride, so the may form a dimer.
Dear Micael
Try to add a solution of sulfonylcloride (1 eqv.) in THF to hydrazine monohydrate (1.05 eqv.) in THF at room temp. with stirring for about 30 min., heat to 40- 50 deg. for further 15 min., then pour the reaction mixture into water and filter to get your product.
Good Luck
How to synthesise the corresponding hydrazide from pentafluorobenzene sulfonyl chloride? I did its dropwise addition to hydrazine monohydrate in THF but that is not working.
Hydrazine synthesised by heating corresponding ester and hydrazine hydrate are almost pure. Therefore no need of further purification only water work up should be sufficient...