SYNTHESIS OP A NEW DIQUINOLIN. 37 



The crystalline base that was so easily obtained from its alcoholic solution was 

 recrystallized from dilute alcohol until its melting point became constant and three com- 

 bustions were made which gave the following results : — 



, Experiment > 



Theory for C.^» H^ N.. i. ii. iir. 



a>o = 8--451% ... ... 84-42 84-55 



H,„= 5-63% ... ... 5-69 5-ri .... 



No = 9-86% ... ... 9-91 



These results confirm the formula C^^ H,,; N.., and justify the representation of the 

 reaction (Skraup's) by the following equation : — 



C, H3 (C H,) N ir, C, II, (C H,) N (C, H,) 



I + 2 (\ H, 03= 1 + 6 H, O + 2 H, 



C, H3 (C H3) N H, C„ H, [C H3) N (C3 H3) 



Ortho-tolidin. Gbjcerinr. Dimethyl diqiiinolin. 



Dimethyl diquiuolin crystallizes in long, slender, colourless needles. It possesses 

 no taste and is without odour. It is very stable and is not readily altered by long exposure 

 to air and light. It is very soluble in alcohol, ether, benzol and chloroform ; slightly 

 soluble in ligroin and petroleum ether and almost insoluble in water. Its alcoholic 

 solution is neutral to litmus. The crystals melt at 188° C. without decomposition, and 

 boil at about 250° C. 



-Salts of Dimethyl Diquinolin. 



TJie Hydrochloride. 



The base readily dissolves in hydrochloric acid, forming a hydrochloride which crys- 

 tallizes from strongly acid solutions in short, strong prisms. This salt at once dissociates 

 into the base and free hydrochloric acid on the addition of water. It was obtained in a 

 pure state by concentrating the hydrochloric acid solution, filtering otF the crystals by aid 

 of a pump, washing with absolute alcohol, recrystallizing from absolute alcohol, and dry^- 

 ing in vacuo over sulphuric acid. The salt so purified gave on analysis the following 

 results : 



Theory for C.^ H„ N, (H CI), Obtained. 



CI = 19-88 % 19-76 % 



The Chloroplatinate. 



The hydrochloride forms with platinic chloride a very insoluble double salt, which 

 when first precipitated is quite amorphous, but rapidly becomes crystalline on standing 

 in an acid solution. Owing to the ease with which the hydrochloride dissociates on 

 dilution, a very concentrated solution of platinum chloride must be employed and the 

 crj^stals well washed with absolute alcohol. 0-8052 grm. of the salt left after ignition 

 0-2166 grm. of platinum = 26-86 '/ Pt. 



Theory for C,„ H,„ N., 2 II CI Pt CI,. 2 R, = 26 9] '/ Pt. 



The two molecules of water of crystallization were retained after four hours' drying 

 at 110" C. The salt crystallizes in short microscopic octahedra of a deep orange-yellow 



