346 Mr. C. H. Browning and others. Relationships between 



could not be obtained in the crystalline form from other solvents. To a 

 second portion picric acid was added which precipitated the picrate in yellow 

 clusters of microscopic needles. 



[15.] Tetrahydroquinoline was prepared according to the method of Hoffmann 

 and Konigs,* by reduction with tin and hydrochloric acid. The hydrochloride 

 crystallised from alcohol in colourless needles, m.p. 181-2°. 



[16.] Methyl tetrahydroquinoline methiodide. — Tetrahydroquinoline obtained 

 from the hydrochloride (2 grm.) was mixed with 14 grm. of methyl iodide at 

 the ordinary temperature. A clear pale orange solution was obtained, from 

 which oily drops separated and gradually solidified to a crystalline mass. The 

 product was warmed on the water-bath with reflux for about 1 hour, and left 

 overnight at room temperature. The excess of methyl iodide was then driven 

 off and the yellowish crystalline mass dissolved in water and filtered. To the 

 filtrate ammonia was added until alkaline and the methyl tetrahydroquinoline 

 extracted with ether. The aqueous solution was evaporated nearly to dryness 

 on the water-bath and cooled. The solid residue was pressed on a porous 

 plate and then extracted with alcohol. On the careful addition of ether the 

 methiodide was precipitated in colourless needles, m.p. 171-2°. 



[17.] u-Naphthoquinoline was prepared by Knueppel's method, f applied to 

 a-naphthylamine by Claus and Imhoff.+ It was purified by crystallisation 

 from petroleum ether and formed colourless needles, m.p. 45°. The metho- 

 sulphate was prepared by dissolving the naphthoquinone in benzene and 

 adding an equal quantity of methyl sulphate and heating on the water-bath 

 for a short time. Pale yellow needles of the quaternary compound separated 

 which were filtered and dried. 



The methochloride was obtained by adding cone, hydrochloric acid and 



CH, CI 



8. Hydroxyquinoline methocMoride. 



CH 2 



* ' Ber.,' vol. 16, p. 728 (1883). 

 t ' Ber.,' vol. 29, p. 703 (1896). 

 | ' J. prakt. Chem.,' vol. 57, p. 68 (1898). 



