213 



limits 172 and 181° C, but the bulk distilled from 

 175-178° C. The distillate had a rotation of -3-4°; refrac- 

 tive index, 1"4814; and dispersion, 0'01294. No violet colour 

 was formed on standing with Schiff's reagent for 20 minutes. 

 The resulting impure cymene was shaken with four successive 

 quantities of Beckman's chromic acid mixture and steam 

 distilled. It was then shaken with potassium permanganate 

 solution in the cold, steam distilled, and collected in two 

 fractions. The first fraction had an odour strongly reminis- 

 cent of cineol, while that of the second fraction was more like 

 cymene. This latter fraction was digested with sodium for 

 a day, distilled and collected in two fractions : — 





Rotation 



(a.) 175°-178°C. 



+ 1-48° 



(b) 178°-180°C. 



-0-44° 



The first fraction (a) was shaken with excess of potrassium 

 permanganate solution in the cold and steam distilled. The 

 distillate, which had a rotation of — 0*26° and a refractive 

 index of 1*4872, was digested over sodium metal and again 

 distilled, when it boiled constantly at 177° C. ; after drying, 

 it gave the following results on combustion: — Carbon, 88'05 

 per cent. ; hydrogen, 10'38 per cent. Theoretical for cymene: 

 carbon, 89'48 per cent. ; hydrogen, 10*52 per cent. 



A portion of the same sample on oxidation with hot 

 potassium permanganate solution, as recommended by Wal- 

 lach, yielded parahydroxy isopropyl benzoic acid, which on 

 repeated crystallization melted at 158° C Another separa- 

 tion of cymene and terpenes from steam distillation A 6 (a), 

 by means of resorcinol solution gave a sample with a rotation 

 of —12*05° and a specific gravity of 0*8536. After repeated 

 digestion with sodium metal, 128 ocs. were distilled and col- 

 lected as follows : — 



Temperature. 



Amount. 



Rota- 

 tion. 



Specific 

 Gravity. 



Refract. 

 Index. 



Disper- 

 sion. 



(a) Below 175° C. 



(b) 175°-178°C. 



(c) 178°-181°C. 



(d) 181°-184°C. 



11 ccs. 



56 CCS. 



26*5 CCS. 



4*5 CCS. 



- 6-7° 



- 9-6° 

 -11-6° 



-10-5° 



0-8567 

 0-8552 

 0-8559 



1-4777 

 1-4795 

 1-4821 

 1-4832 



0-01255 

 0-01288 

 0-01343 

 0-01344 



The rotation of the above fractions is almost certainly 

 due to laevo -rotatory terpenes. 



Limonene. — Although these fractions contain cymene, 

 there is little doubt, judging from the boiling point, specific 

 gravity, and other characteristics, that limonene is also pre- 

 sent, and that the laevo-rotation of the above samples is due 

 to this terpene. 



