62 BACON. 



the constitution of this addition product. The simplest assumption would 



V C,H,C— 0— MgCl 



assign to it a formula CgHjCOMgCl. The structure H 



C,H,C-0-MgCl 

 does not seem probable, for neither benzoin nor benzil could be found 

 among the substances obtained b}' decomposing the compound with water, 

 excepting in one experiment (number 8) where heat was used for a 

 long time and where this result was to be expected. However, it is 

 certain that when benzaldehyde acts on the etherial compound of hydro- 

 limonene magnesium chloride, the former reacts as it would do if it 

 contained a hydroxyl group. As in this instance benzaldehyde reacts as 

 if it were an alcohol, it is not surprising to find that acetone does the 

 same, as acetone often assumes the enol form dxiring reactions as, 

 for instance in the production of sodium acetone and during its con- 

 densations, many of which are best explainable on the assumption of 

 a compound of the structure CH., . COH : CH,. It was nevertheless 

 deemed advisable to undertake an experiment with acetone as the reagent. 



Experiment 12. — ^Tliere were used limonene hydroelilorkle, 35 grains; magne- 

 sium, 10 grams, and absolute ether, 100 cubic centimeters. Tlie Grignard reac- 

 tion was allowed to take place in a bromine ilask, after it was complete, 

 13 grams of carefully purified and dried acetone were slowly added. A con- 

 siderable evolution of heat, as is the ease with benzaldehyde, was observed and 

 the separation of a solid which at first was red, then yellow and finally white 

 took place. After the reaction has ceased, the product was treated as was the 

 case when benzaldehyde was the reagent. The neutral oils were distilled in 

 vacuo and gave the following fractions : 



No. 1: B. P. 73° to 80° at 1.5 millimeters, 20 grams. 



No. 2: B. P. 80° to 110° at 15 millimeters, 7 grams. 



No. 3 : Residue, 2 grams. 



Number 1 was identified as CioHis as it had the following constants : Boiling 



point, 174° to 176°; specific gravity, -2^^=0.8280; N^ = 1.4630. 



4 D 



Number 2 contained a considerable amount of chlorine and the oil was doubt- 

 less a mixture of unchanged limonene hydroeliloride and diterpenes. The method 

 of Deniges " showed 12,6 grams of acetone to be present in the aqueous solution. 



This result is parallel with the one olitained with benzaldehyde and 

 therefore, in this reaction, also, acetone assumes the role of propen- 

 l-ol-S. 



These experiences with limonene hydrochloride were of sufficient in- 

 terest to warrant a study of the action of benzaldehyde on other magne- 

 sium organic halides, for it might be true that in each instance a certain 

 proportion of the reduced hydrocarbon might be produced, owing to the 

 small percentage of the enol form present in the aldehyde ; with tliis 

 end in view a study of the reaction between benzjd magnesium cliloride 



"""Compt. reiuh d. Acad. sci. Par. (1898), 127, 963; Ann. Chiin. Phtjs. (1899), 

 (6), 18, 400. BullSoc. Chim. (1899), (3) 21, 241. 



