Chemistry. — ''On the eMiwation of the yemniol content of citro- 

 ne/la oil". Bj Dr. A. VV. K. de Jong, (('oinmunicated hv 

 Prof. VAN Romburgh). 



( Communicaled in the meeting of September 29, 1918). 



The chemists of tlie firm of Schimmrt, & Co. have a method for 

 the estimation of geraniol in oitioiiella oil which in the "Bericht" 

 of tiiis firm of October 1899, 20 and also in that of October 1912, 

 39, is described as follows: "Etwa 2 g- Phthalsaureanhydrid iiiuri g 

 des zii uiitersiiclienden Oels werden mil 2 ccm Benzol zwei Stunden 

 in einem Kolben, wie er zn Acetyliernngen beiuilzl wird, anf dem 

 Wasserbad erwiirmt, dann erkalten gelassen nnd mif 60 ccm wassriger 

 Halbnormal-Kalilauge 10 Minuten geschüttelt. Der Kolben ist hierbei 

 mit einem eingeschliffenen Glasstopfen \ erschlossen. Nach dieser Zeit 

 ist alles Anhydrid in neutrales phlhalsaures Kali und der saure 

 Geraniolester in sein Kalisalz iibergeführl worden. Nun wird das 

 überschussige Alkali mit Halbnormal-Schwefelsaure /iinicUtitriert. Zieht 

 man dann von der Menge Alkali, die der eingewogenen Phthalsaure 

 entspricht, die fiir den Versuch vei'brauchte iMenge ab, so erfahrt 

 man, wieviel Alkali dem an Phlhalsaure gegangenen Geraniol aqni- 

 valent ist, woraus der Prozentgehalt an Geraniol zu berechnen ist". 



This method is at the outset subject to suspicion, since it is based 

 on the assumption that geraniol is quarititativelj eslerified by phtha- 

 lic anhydride, whereas this is not even the case with acetic anhy- 

 dride (98.5 p.c. was found to be esterilied). 



For the following experiments a very pure phthalic anhydride 

 was prepared; 1 grm. was neutralised by 135 c.c. Vio •> KOH, where- 

 as 135.1 c.c. was calculated for the pure substance. 



The citronellal used was isolated from citronella oil by means of 

 the bisulphite compound. The sp. gi'. at 26^ wasO.8526 ; [«]i)=-[-lO°2r. 

 It was faintly acidic; 1 grm. was neutralized by 0.2. c.c. Vio " ^^^H. 



The geraniol was isolated from Palmarosa oil by means of the 

 calcium chloride method. The sp. gr. at 26° was 0.8752. 



To the mixture of aidiydride, citronellal or geraniol 4 c.c. of 

 benzene was added. After heating, the flask was cooled 'rapidly, so 



