[KriFar]

Hi all! I am trying to synthesis the 2-hydrazineanthracene from the 2-aminoanthracene.

The methods that I tried proceed via the diazonium cation and then reducing it. The 2-hydrazinanthracene should be formed as the HCl salt which then can be dissolved in water and precipitate the free base with sodium acetete.

I am preparing the diazonium cation by partially dissolving the 2-aminoanthracene in 6M HCl (it does not dissolve-remains as a suspension) and cooling the solution below O⁰C. Then I slowly add NaNO2/H2O to the acidified solution. A red/orange colour forms. Then I quickly filter the solution and add it very slowly to a bascified solution of sodium sulfite. An intense dark red solution forms. I leave the solution stirring for few hours and then I add conc. HCl and heat solution for 3 min (At 25^oC). Brown solid separates. I leave the acidified solution to stand overnight and then filter it. The residue collected is re-dissolved in con. HCl and heat it, to aid the formation of the hydrochloride salt. The solution is filtered again and then dissolved in water (only partially dissolved even if a very large quantity of water is added). Concentrated solution of sodium acetate is added to liberate the base.

A very dark brown, almost back powder is collected which fluoresce blue green under 365 nm. When doing NMR of this solid in DMSO-d₆ no sharp signals are present but only 2 small broad peaks in the aromatic region are observed.

Any suggestions of what is going on? An how I can change my synthesis method?