﻿THE TERPENE OILS OF MANILA ELEMI. 23 



a considerably higher boiling point. Sulphuric acid in dilute alcohol, 

 hydrates a large percentage of limonene. 



( 1 ) Twenty grams pure dextro-limonene were dissolved in 50 cubic centimeters 

 of acetic acid of 99.5 per cent strength, and to this was added 1 gram of dilute 

 sulphuric acid ( H 2 S0.,,3H,0 ) . This mixture was heated in a flask on a water- 

 bath for seven hours, the flask having been connected with a calcium chloride 

 tube in such a way as to prevent the access of moisture. Soon after the heating 

 began, two layers formed. The product was finally thrown into water and the 

 oil removed with ether, after which it was washed with sodium carbonate to 

 remove acetic acid and then distilled with steam. The entire amount of distillate 

 obtained was not over 2 grams; the residue was tarry. The limonene had been 

 almost completely polymerized. 



(2) Thirty grams of pure limonene were dissolved in 20 grams absolute alcohol 

 and 1 cubic centimeter of dilute sulphuric acid (H 2 S0 4) 3H 2 0) added. Access of 

 moisture was prevented by means of a calcium chloride tube and the flask 

 containing the mixture was heated just to boiling on a water-bath for fifteen 

 hours, during which time the mixture became reddish brown in color. The 

 product was finally poured into cold water and the oil separated. The latter 

 was again shaken out with cold water and then driven over with steam. There 

 had not been much polymerization. The distillate was dried over solid potassium 

 hydroxide and then distilled. Two fractions of equal amount were obtained, 



(1) from 184° to 193°, and (2) from 193° to 200°; both showed only a slight 

 rotation. Neither one gave a crystalline hydrochloride in acetic acid or a 

 tetrabromide in amyl alcohol and ether. The first fraction gave no test for 

 phellandrene but a very small amount of terpinene nitrite which had a melting 



point of 153°-154° appeared on standing. The first. fraction showed n ^=1.4726 



30 



and the second n -£>= 1.4690. Since there could have been very little hydration, 



the product is composed mostly of unknown terpenes. 



(3) Forty grams of pure dextro-limonene were dissolved in 350 cubic centimeters 

 of absolute alcohol and to this was added 35 cubic centimeters of a mixture of 

 1 volume concentrated sulphuric acid and 5 volumes water. This mixture was 

 boiled in a flask with a reflux condenser for seven hours on a water-bath. The 

 alcohol was then partly distilled off and the residue driven over directly with 

 steam. There was only a small amount of non-volatile residue. The distillate 

 was separated from water and fractioned twice. The first time it boiled from 

 186° to 218° and on the second fractionation the following portions were 

 separated. (1) 180° to 186°, 30 per cent of the total; (2) 186° to 193°, 25 

 per cent; (3) 193° to 200°, 15 per cent; and (4) 200° to 215°, 30 per cent. 

 During the distillation a small amount of water appeared continuously to be 

 formed. In the first fraction no phellandrene could be detected, but a small 

 quantity of crystals, probably terpinene nitrite, formed on standing. They were 

 contaminated with resinous matter and an accurate determination of their 

 melting point, which was not far below 155°, was impossible. The same fraction 

 gave a good quantity of crystalline tetrabromide in acetic acid. After recrystal- 

 lizing twice, this product melted from 112° to 115° and is therefore probably a 

 mixture of limonene and dipentene tetrabromides. The higher-boiling fractions 

 were not very carefully investigated. An unsuccessful attempt was made to 

 prepare a phthalic acid-ester by the action of phthalic anhydride upon fraction 

 (4) in benzol solution. The products obtained in this, experiment should be 

 further studied. 



