1889.] 



Chemistry of the Camphoric Acids. 



9 



Separation of the Mixed Acids. 



Anschiitz's acetyl chloride reaction furnishes a particularly neat 

 method of separating the two acids. The anhydride of the dextro- 

 acid formed by the action of the acetyl chloride is separated from the 

 apparently unaltered laavo-acid by treatment with carbonate of soda, 

 which dissolves only the latter. 



Nature of the more soluble Syrupy Product of the Action of Water 

 on Camphoryl Chloride. 



This substance, which resembled the mixture of dextro- and laevo- 

 acids above described, was subjected to the same process of separation, 

 by which exactly the same products were obtained. 



Thus the action of water on the acid chloride is such as to give 

 about equal quantities of laavo- camphoric acid and the anhydride of 

 dextro-camphoric acid, a small portion of latter being further converted 

 into the acid. 



Optical Activity of Camphoryl Chloride and Camphoric Anhydride. 



It might be supposed, from the circumstances just mentioned, that 

 camphoryl chloride which yields both dextro- and laavo-canrphoric 

 acids would be itself inactive. This, however, is not the case. I have 

 always found camphoryl chloride to be leevo-rotatory, though I have 

 not found a perfectly constant number to express its value. For the 

 undiluted substance I have found [»] D = —3*0°, and —3*6°, while 

 for the substance dissolved in crude benzene the rotation is about 

 twice as much, viz., [#]d = — 7'1° and — 8*3° ; the latter value being 

 obtained with the same specimen of camphoryl chloride which gave a 

 rotation of 3'6° when undiluted. The rotation is, indeed, greater than 

 that of camphoric anhydride, a substance which yields only one cam- 

 phoric acid. I have found the specific rotation of camphoric anhydride 

 in pure benzene to be —3* 7°, and very little different in the same 

 benzene which was employed for the camphoryl hloride. De Mont- 

 golfier has given a higher value, — 7° 7', for camphoric anhydride, 

 which 1 am unable to confirm. 



Tlx eoretica I C onsiderations. 



If we wish to interpret rightly the foregoing facts, we shall, 1 

 think, find it impossible to regard the laavo- camphoric acid as the 

 optically opposite isomer of the ordinary acid. On the other hand, 

 there would appear to be a probability, almost amounting to certainty, 

 that these two acids are related to one another as maleic and fumaric 

 acids, the dextro-camphoric acid corresponding to maleic and the 

 laevo- to fumaric acid. The isomerism is further complicated by the 

 presence of rotatory power which requires the existence of two other 



