However, reaction of the tetrazole 10 with triphenylphosphine in boiling benzene affords in 70% yield the open chain phosphazene 11, which can easily by hydrolyzed to the aminopyr- idazine 12. A problem exists in the isolation of the 3-amino-5-hydroxy~ 6-phenyl-pyridazine (12) when using the standard hy-drolysis method with aqueous hydrochloric acid (procedure D. 1 in the experimental part), as described in the Staudinger method “and used in various ...