84 REPORTS ON THE STATE OP SCIENCE. — 1915. 



jt,j = 60) and acetoplienetidide (in =90), in each of which are two 

 directing groups, alkoxy- and acetamino-. Moreover, the products of 

 the chlorination should in these compounds be a mixture in which the 

 chloro- compound formed under the influence of the alkoxy- group 

 would largely predominate, thus : 



OAlk 



Alk 



NHAc 



NHAc 



As nothing at the time was known of the activity of the alkoxy- 

 groups in directing substitution, we * took the monochlorophenetidide, 

 which we isolated only by repeated crystallisation of the first product, 

 to be 5-chloroacetphenetidide. The relatively greater activity of the 

 ethoxy- group would indicate that the chloro- derivative in larger 

 proportion is the isomeric 2-chloroacetphenetidide. Professor J. F. 

 Thorpe has, moreover, recently prepared the 5-chloroacetphenetidide 

 and demonstrated its constitution undoubtedly, and has further shown 

 that the compound which we isolated is 2-chloroacetphenetidide. 



(3) A Comparison of the Amino- and Hydroxy- Groups. — A direct 

 comparison between the amino- and hydroxy- groups in their activities 

 in directing chlorination is not very easy to obtain ; the speeds of 

 entrance of the first and second atoms of chlorine into aniline and 

 phenol are very high; the introduction of the nitro- group, which 

 lowers the speed of chlorination, is not pennissible owing to its specific 

 effect, mentioned in the foregoing, on the hydroxy- group. Moreover, 

 a further difficulty in obtaining an exact relation arises from the great 

 difference in the activities of the two groups. The most trustworthy 

 method is found in the measurement of the rate of entrance of the 

 third chlorine atom into 2 : 4-dichloroaniline and 2 : 4-dichlorophenol 

 respectively. The value of ^iil8.4° for the aniline is about 600, and 

 that for the phenol approximately 0'16. 



Stimmary. — The amino- group far surpasses all other groups in 

 activity in chlorination of aromatic compounds, and is followed by the 

 groups, hydroxy-, alkoxy-, and acetamino- in the order given. 



NH2 > OH > OAlk > NHAc. 



The Committee ask for reappointment, and for a grant of 101. for 

 the year 1915-16. 



* Orton and King, loc. cit. 



