Hydrazine dihydrochloride

A few days ago I had a go at making hydrazine dihydrochloride. Hydrazine dihydrochloride is a salt of hydrazine with the formula N2H2.(HCl)2. It's a white crystalline solid used as a convenient source of freebase hydrazine in organic chemistry. It is present in some soldering fluxes. I plan to use mine for making azides.

To make it I started by adding 250ml of chilled 5%ish sodium hypochlorite solution to a 1 litre beaker. I then dissolved 16 grams of sodium hydroxide slowly into the hypochlorite solution (to insure the reaction environment is alkaline). In a new beaker I prepared a solution of 0.375 grams of gelatine (the role off the gelatin is unkown) and 11 grams of urea in around 40 millilitres of water. I then quickly added all of the gelatine/urea solution to the hypochlorite hydroxide solution and started stirring with vigour. A bit of foaming was observed (probably due to partial product decomposition to nitrogen). The reaction mixture was then heated up to 85-90 C for 6 minutes to form the hydrazine. Next it was chilled close to 0 C and then 117 millilitres of 33% hydrochloric acid was added slowly with brief gentle stirring at each addition. The hydrazine must be neutralised twice: first to make hydrazine monohydrochloride, which is very soluble, and next to make hydrazine dihydrochloride, which will partially precipitate.

After a few minutes, crystals of hydrazine dihydrochloride were observed precipitating. These were collected via filtration, and dried. The product is shown below:

Overall this worked terribly, requiring TWICE as much acid as would have been used forming hydrazine sulphate. The yields were horrible. Next time I do this I'll use sulphuric acid at the end, and make hydrazine sulphate.