106 BACON. 



Tliese experiments show that a reactioUj which is very different from 

 the normal one between ortho-formic ester and organo-magnesium 

 halides, had taken place. It is to be noted that the great tendency in 

 the terpene series during reactions of this nature, is to produce the 

 reduced terpenes. To exclude any possibility that these reduced ter- 

 penes might result from the action of the sulphuric acid used in decom- 

 posing the reaction mass, or any excess of magnesium, I attempted to 

 reduce limonene, a phellandrene, and /3 phellaudrene with magnesium 

 and dilute sulphuric acid. The results were absolutely negative. The 

 refractive index of the terpene was in each case the same before as after 

 the attempt at reduction. 



Oxygen reacts with hydrolimonene magnesium chloride to give ter- 

 pineol as is shown bj' the following result : 



One hundred and ten grams of limonene hydrochloride, 20 grams of magnesium, 

 300 cubic centimeters of absolute ether. After the reaction according to Grignard 

 was completed, I ran a copious stream of dry oxygen into the apparatus during 

 eight hours. There was a considerable evolution of heat and reddening of the 

 mass. The products of the reaction were decomposed by means of a cold solution 

 of ammonium chloride, and the resulting oils were fractional in vacuo. Nine 

 grams of terpineol, boiling between 98° and 102° at 9 millimeters' pressure were 



thus obtained; specific gravity, ?^° =0.930; N?1° = 1.4805; A?2!=15°.2. The 



phenyl urethane derivative was prepared in a solution of petroleum ether and 

 when once recrystallized melted at 112° to 113°. The lower boiling fractions of 

 this oil (78 grams), boiling between 172° and 175° at ordinary pressure, still had 



some terpeneol odor. Specific gravity, 2^=0.8250 ; N^" =1.4617. Therefore, this 

 oil probably consisted largely of the dihydroterpeue C,oH,s. 



LTMONESE HYDROBEOMIDE. 



Seventy-five grams of dry limonene, dissolved in an equal volume of drj- petro- 

 leum ether, were saturated with dry hydrogen bromide. Distillation in lafuo 

 gave 45 grams of limonene hydrobromide, boiling between 108° and 112° at 12 



millimeters' pressure; specific gravitv. -—=1.1209; N'i~^ = 1.5006. 



° •• 40 'J) 



Found 



Calculated 



per centi. 



(per cent). 



35.8 



36.4 



Br. 



Limonene hydrobromide was allowed to react according to tlie method of 

 Grignard with 8 grams of magnesium. The reaction is more vigorous than with 

 the corresponding hj'drochloride. A test-tube experiment showed that the hydro- 

 limonene magnesium bromide did not react with chlorocarbonic ester. Twenty 

 grams of benzaldehyde were then added to the hydrolimonene magnesium bromide. 

 The reaction was very vigorous, a yellow solid separating just as in the similar 

 reaction with the hydrochloride. The products obtained were principally benzal- 

 dehyde and dihydrolimonene. The reaction vvith benzaldehyde is, therefore, exactly 

 the same as when limonene hvdrochloride is used. 



