36 E. F. EUTTAN OlST THE 



uncertainty. The numérotas derivatives of ortho-tolidiu studied by others as well as by 

 myself, point to the conclusion that this rare base is a double aromatic amine and yields 

 derivatives similar to the simple primary aromatic bases. 



Skraup and Kouig ' some years ago published a method of preparing simple quino- 

 lins from primary aromatic amines. This method has proved of very general application 

 and has since been used for preparing quinolius in large quantities in aniline works, etc. 



Skraup's reaction for the synthetical production of quinolins is a condensation pro- 

 cess accompanied by a loss of the elements of water and oxidation. The method consists 

 in heating a primary aromatic amine for a suitable time to a high temperature with 

 glycerine, strong sulphuric acid and an oxidizing agent, preferably a nitro-componnd ; 

 thus quinolin is prepared from aniline according to the following equation : — 

 C, H, NH, + C, H, 0, = C, H, N (C, H,) + 3 H, O + H,. 



This reaction really occurs in two stages, acrolein aniline being first formed, from 

 which quinolin is derived by the withdrawal of a molecule of hydrogen. 



A modification of Skraup's reaction was used in the preparation of the diquinolin, 

 which forms the subject of this communication. 



Owing to a want of proper adjustment of temperature and quantities the application 

 of this reaction to ortho-tolidiu was at first only partially successful ; very small quanti- 

 ties of basic products were obtained. A good yield — over fifty per cent of the theoretical 

 quantity — was obtained under the following experimental conditions : — 



In a round bottomed flask of about two litres capacity, fitted with a reflux condenser, 

 were mixed 40 grms. of the sulphate of ortho-tolidiu, 200 grms. of sulphuric acid 

 (sp. gr. 1-84) and 50 grms. of ortho-nitro-toluol. This mixture was heated to 120°- 130° C, 

 and 240 grms. of pure anhydrous glycerine slowly added with occasional agitation. The 

 temperature was then raised to about 150° C, the flask being occasionally shaken until a 

 violent reaction ensued which lasted a few minutes, during which the source of heat was 

 withdrawn. After all ebullition had ceased the contents of the flask became quite thick 

 and tarry, but at this stage no basic substance could be detected in the mixture except 

 some undecomposed tolidin. The temperature was raised to 180°-190° C, and this con- 

 dition maintained for from four to six hours, when a good yield of new basic products 

 was obtained. 



After the excess of nitro-toluol was distilled off the bases were separated from the 

 cooled residue by strong potash. The tarry mass so obtained was extracted with benzol 

 and benzol extract evaporated. This residue was treated with hot alcohol until nothing 

 more was dissolved ; the hot alcoholic extract, decolourized by filtration through animal 

 charcoal, yielded on cooling a base which separated as a mass of interlacing needle shaped 

 crystals. 



Besides this base another basic product or group of bases could be obtained from the 

 benzol residue insoluble in alcohol by using other solvents, such as ether and benzol. 

 The quantity obtained was always small and the substance was not crystalline. From 

 the nature of some salts obtained, as well as from some micro-chemical reactions of this 

 by-product, it seemed to consist of a mixture of bases possessing alkaloidal properties. A 

 sufficient quantity was not obtained to pei'mit of the separation of any substance possess- 

 ing the characters of a chemical individual. 



' Proc British Ass., 1886. 



