The Orton rearrangement N-haloanilides

Slosson3 showed that the N-bromoanilides I and III also underwent rearrangement to give the corresponding para bromo compounds II and IV, viz. 

In general the para isomer is the main product but about 5 % ortho isomer was detected6 when the solvent was aqueous acetic acid. All the evidence suggests that the rearrangement is intermolecular involving the reversible formation of free chlorine and the anilide, reaction (2), followed by C-chlorination of the anilide, reaction (3) 

The evidence for this is based on the facts that (a) chlorine can be aspirated from the reaction mixture, (b) in the presence of more reactive aromatic compounds cross-chlorination occurs as in the reaction 

The results of kinetic studies on the rearrangement (which have been sum- 

This third-order rate equation is interpreted as meaning that the process is first-order in each reactant, viz. N-chloroacetanilide, chloride ion and hydrogen ion. This has been confirmed10 for the reaction of N-chloroacetanilide with hydrogen bromide in a variety of aqueous media, under conditions where the dechlorination is rate-determining. The rate equation is 

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