5-Chloroacridine and its derivatives have been dehalogenated by condensing them with toluene-p-sulphonylhydrazide and heating the resulting adducts with dilute alkalis. This reaction makes possible for the first time the transformation of those 5-chloroacridines (and hence acridones), which have easily reducible groups (e.g., *CN and *NO,), into the corresponding acridines.The formerly difficult steps of chlorinating an aminoacridone to an amino-5-chloroacridineJ followed by replacement of the chlorine atom, have been satisfactorily accomplished for 3-aminoacridone by first converting it into the carbethoxy-derivative.IT would be valuable to have a standard method for replacing an active chlorine atom in heterocyclic compounds by hydrogen without the use of hydrogenation or reducing agents. I n this way, the hydrogenation of the nucleus could be avoided and the integrity of such easily reducible groups as *NO, and *CN preserved.-+ (111.) C,H,Me*SO,H c1-(11).The reductive dehalogenation of 4-chloro-3-nitro-6 : 7-benzquinoline, recently accomplished by means of toluene-p-sulphonylhydrazide (Albert, Brown, and Duewell, J . , 1948, 1284), seems to be such a general method, and the present work describes its successful application in the acridine series. As 5-chloroacridines can be prepared quantitatively from the corresponding acridones by the action of phosphorus oxychloride, it can also be used to transform acridones into acridines. The only other recorded attempt to perform a reaction similar to (I1 + 111) in a heterocyclic system was made by Dewar ( J . , 1944,6 19) on 4-chloro-8-nitro-6-methoxyquinazoline.The yield was only S%, but the conditions used were different from those worked out here. 5-Chloroacridine (I) was mixed with toluene-fi-sulphonylhydrazide in chloroform solution. Next day, the adduct, 5-N'-(toluene-p-sul~honyZ)hydrazinoacridine hydrochloride (11) was filtered off and heated with alkali, in aqueous ethylene glycol, a t 97" for 2 hours, The products (111) of this reaction are acridine, nitrogen, and . toluene-p-sulphinic acid. The sulphinic acid was identified by conversion into 2 : 4-dinitrophenyl p-tolyl sulphone (m. p. and mixed m. p. confirmed). The yields of dehalogenated acridines from 5-chloroacridine and also from six substituted 5-chloroacridines are shown in the annexed table. The maximal yieIds range from 40 to 73% calculated on the chloroacridine taken. The ratio of alkali (about a tenfold excess) to adduct was not varied, but the volume of solvent was changed, thus maintaining different concentrations of hydroxyl ion. Sodium hydroxide is too destructive for the cyano-and nitro-derivatives, and in these cases the best yields were obtained with very dilute sodium carbonate.Results with other alkalis (including glycine-, cyclohexylamine-and piperidine-buffers) and solvents (including water) were far inferior.2-Chloroacridine was obtained in two interconvertible modifications, m. p. 129" and 134", respectively, thus resembling 1-chloroacridine (forms, m. p. 79" and 90" ; Clemo, Perkin, ...
