In dipolar aprotic solvents, nitranions derived from anilines of enhanced N -acidity displace fluorine from activated aromatic compounds at room temperature. Diarylamines thus produced are free from triarylamines, which are formed at higher temperatures when diarylamines, after N-deprotonation b y potassium t-butoxide or by the heavier alkali metal carbonates, similarly displace activated fluorine. Certain diarylamines can also be prepared by chlorine displacement in the presence of alkali metal carbonates. It is confirmed that such carbonates play only an auxiliary role in the Ullmann (copperassisted) diarylamine synthesis conducted in dipolar aprotic solvents; they may indeed impede the reaction in some instances.Diarylamines are readily formed by the reaction of activated fluoroarenes with arylamines containing electron-releasing groups; ' the corresponding displacement of fluorine, nitro groups,, and the other halogens by arylamines containing electron-withdrawing groups requires activation of the amine by a base capable of effecting partial or complete removal of a proton from the acidic NH, group (Scheme 1). R'R 21) (2) (3) R', R2= electron-withdrawing groups M = a n alkali metal X = h a l o g e n or nitro group Scheme 1. Conditions: In dimethyl sulphoxide (DMSO): (A) at 12& 150 "C; (B) at 2 G -2 5 "C

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The effects on activity against Schistosoma mansoni of further modifications of the diaminodiphenoxyalkanes are reported. Replacement of the amino‐group by any of a large number of other groups destroys activity. Activity is retained in the presence of certain substituted (hydroxyalkyl, carboxyalkyl) amino‐groups and in some of their aldehyde‐bisulphite derivatives. Many variations of the central chain lead to compounds of reduced activity, the outstanding exceptions being a number of but‐2‐ene derivatives, which retain full activity.