TERPENES AND ESSENTIAL OILS, I. 63 



and benzaldelij'cle was undertaken. Thus Grignard" states that benzyl 

 magnesium halides do not react in the normal manner with aldehydes, 

 the principal product of the reaction being diljenzyl, and Hell'" and his 

 students, depending upon the conditions, obtained both the carbinol and 

 stilben in this reaction. 



Several experiments imder varying conditions were performed and 

 phenyl-benzyl carbinol was always obtained in large quantities, but in 

 no case could toluol be detected. Phenyl-benzyl carbinol is readily ob- 

 tained in the pure state by distillation of the reaction product in vacuo. 

 It boils from 167° to 170° at 10 millimeters pressure and immediately 

 solidifies in the receiver, the room temperatiu-e being 30° to 33°. Hell 

 speaks of the difBculty he experienced in obtaining the carbinol in a 

 solid form when working in the summer. Crystallized twice from li- 

 groin (in which solvent when it is boiling it is Cjuite soluble, whereas 

 it is almost insoluble in the cold), it melts at 67° to 68°. The melting 

 points given for phenyl-benzjd carbinol in the older literature are too 

 low.i" 



"With concentrated sulphuric acid it gives a white tar, just as benz- 

 hydrol gives a red tar with the same reagent. 



As the method of preijaring benzhydroP'' in quantity has in the past 

 been tedious to apply, and as the Grignard reaction was under considera- 

 tion, it was decided to ascertain if it might be available for this purpose. 

 Using chlor- or broni-benzol, magnesium and ether, and treating the 

 reaction product with benzaldehyde, the results leave nothing to be de- 

 sired as to yield, ease of manipulation and time consumed, so that this 

 method will imdoubtedly replace the longer ones formerly used in pre- 

 paring this compound. 



Limonene hydrochloride reacts with magnesium to form a hydro- 

 limonene magnesium chloride, solul^le in absolute ether, the union taking 

 place normally according to the t3fpe of reactions discovered by Grignard. 

 This addition product when decomposed by water gives a dihydro-terpene 



A method is developed by means of tlie Grignard reaction of passing 

 from terpenes and their derivatives to di- and tetrahydro-terj)enes and 



"Ann. de I'Vniversite de Lyon (1901), N. S. 6, 1-116; Ghem. Oentrbl. (1901), 

 II, 623. 



^=Ber. d. Chem. Ges. (1904), 37, 453, 225, 1429. 



•° Limprieht and Schwanert: Ann. chem. (Liebig) , (1870), 155, 02. Gold- 

 berg: Ibid. (1874), 174, 332. Knovenagel and Arndts: Ber. d. chem. Ges. 

 (1902), 35, 1987. Sudborough: ./. chem. ,S'oc. London (1895), 67, 605. Beilstein 

 II, 1079 gives M. P. 42° probably a misprint for 62°. The error has been copied 

 into Richter's Lexikon der Kohlenstoffverbindimgen. 



"Nef: Ann. Chem. (Liebig), (1897), 298, 202. Bacon: Am. Chem. .Tour. 

 (1905), 33, 68. 



