﻿26 CLOVER. 



higher than that found by Schreiner. In fact the numbers given by 

 Wallach for the same product show a considerable variation. Both 

 workers used chloroform as a solvent. By the use of the same solvent 

 I obtained a value agreeing very closely with that of Schreiner, the solu- 

 tion having stood for about ten minutes before the reading was made. 

 It was found later that the reading diminished quite rapidly on standing. 



(1) A solution of 0.35 gram of pure a-phellandrene a-nitrite dissolved in 

 5 cubic centimeters of pure chloroform (Kahlbaum, best quality, shaken out 

 repeatedly with water, dried over calcium chloride and then distilled) lost its 

 optical activity entirely after standing for about four hours. The solvent was 

 evaporated in vacuo. The residue did not crystallize until a small amount of 

 ether was added, which evidently dissolved out some amorphous decomposition 

 products. The recovered product which was fully three-fourths of the amount 

 used originally, was again dissolved in 5 cubic centimeters of fresh chloroform 

 and the solution was found to be slightly lsevo-rotatory, the value being about 

 one-tenth that of the original. 



(2) A solution of 0.3 gram pure a-nitrite in 10 cubic centimeters of chloroform 

 after standing for eighteen hours showed a positive rotation equal to about 

 one-half that of the original negative value. 



(3) A solution of 0.5 gram pure a-nitrite in three or four cubic centimeters 

 of chloroform was allowed to stand over night. The chloroform was then for 

 the greater part removed in vacuo and the residue treated with a small amount 

 of ether. The solid residue was pressed out on a porous plate and again washed 

 with ether. It consisted of a little more than 0.3 gram. When recrystallized 

 from acetic ester it melted at 120° to 121° and the rotation of the recrystallized 

 substance, roughly determined in dilute chloroform solution, was found to be 

 about the same as that of the original pure a-nitrite. 



(4) A saturated solution of the pure nitrite in acetic ester showed a T)= — 6°. 2. 



A reading made some time later demonstrated that the rotation of the solution 

 was decreasing. After standing over night it had changed to +1°.8. The solvent 

 was then removed in vacuo and the residue washed well with ether, only about 

 one-fourth of the weight of original nitrite remaining. When this was recrystal- 

 lized from acetic ester it melted at 119°. 5 to 120°. 5 and showed a rotation ap- 

 proximately the same as the original. 



From above experiments it seems certain that the change in rotation is 

 not caused by a change of the dextro-into the hevo-a-nitrite, although 

 otherwise the results obtained do not appear at all clear. 



Wallach has shown that there is no change in melting point when the 

 dextro-and laevo-a-ni trite are mixed; hence the racemic mixture ap- 

 pears to be very similar to the active forms. It was desired to determine 

 whether the varying rotation found for different samples of phellandrene 

 could be explained by the presence of the racemic modification and it was 

 thought that this could be determined from the rotation of the purified 

 nitrite. In the case of the nitrite from oil XVII,A, purified, the value- 



on 



[a] £ = — 126°. 8 at a concentration of 12.3 was found. The nitrite 

 obtained from XIV, A, purified, gave [a] ^= — 124°. 5 at a concentration 

 of 8.84. Both readings were taken about ten minutes after the solutions 



