ON THE STUDY OF HYDRO-AROMATIC SUBSTANCES. 



263 



Neither dimethyldihydroresorcin nor chloroketodimethyltetrahydro- 

 benzene reacts with secondary amines. The replacement of the hydroxyl 

 group in dimethyldihydroresorcin by a basic group such as NH2-, 

 CgHs.NH-, or C7H7.NH-, causes the remaining ketonic oxygen atom of 

 the dihydroresorcin to become hydroxylic, as shown by the colour reactions 

 of the resulting substances with ferric chloride and their behaviour 

 towards phosphorus trichloride. If, however, the substituting group is 

 rendered more acidic by the introduction of an acetyl group, this second 

 oxygen atom becomes ketonic and is able to condense with semicarbazide. 

 The mono -derivatives produced from dimethyldihydroresorcin can be 

 converted into the di-derivatives directly obtainable from chloroketo- 

 dimethyltetrahydrobenzene either by condensation with a second molecule 

 of the primary base in presence of zinc chloride, or by the action of the 

 phosphorus haloids. 



In a second communication ^ it is shown that molecular proportions 

 of dimethyldihydroresorcin and a primary diamine (w- or^> phenylene- 

 diamine) interact to give an 80 per cent, yield of the simple condensation 

 product (15), but, in addition, there is also formed a small amount of the 



HjC 



CCCH^), 

 /NCH 



HjN . C,H^ . HN . C 



(15) 



CH 



C . OH 



compound (16) resulting from the condensation of two molecules of the 



CCCHj), C(CH3), 



HC /^ CH, HjC ^^ CH 



Cl«) 

 C . NH . CjH, . NH . C 



HO. C 1 



CH 



CH 



C . OH 



dihydroresorcin with one of the diamine. The compounds of formula 15 

 function as di-acid bases, giving rise to dihydrochlorides, which react with 

 one molecular proportion of platinic chloride to form platinum salts ; they 

 are insoluble in water, but dissolve in alcohol to form neutral solutions 

 which produce with ferric chloride a reddish-brown coloration ; with 

 acetic anhydride they yield mono-acetyl derivatives only, which still give 

 a colour reaction with ferric chloride. The di-substituted phenylene- 

 diamines (16) are also di-acid bases having a neutral reaction ; they are not 

 acetylated by boiling with acetic anhydride, and may be recrystallised 

 without change from glacial acetic acid ; in alcoholic solution they give 

 with ferric chloride a reddish-yellow colour. 



Chloroketodimethyltetrahydrobenzene condenses at once with two 

 molecules of m-phenylenediamine to give the hydrochloride of a base 

 having formula 



C(CH3), 



/\CH, 



HjC 



HjN.C.Hj. N = C 



CH 



C . NH . C,H, . NHj 



» J. a S., 1906, 89, 388. 



