- 96 - 



b. p. 73 to 75 (7 to 8 mm. press.), b. p. 205 to 208 (atmosph. press.), 

 diso 0,8560, «d -J - I3°6', n D20 o 1,44710. Its semicarbazone melted at 

 81 to 82 . From 500 g. of oil we isolated about 220 g. of aldehyde. 

 The smaller part of the oil freed from citronellal passed over between 

 45 and 103 (5 mm. press.), the larger portion remained behind in 

 the flask in the form of a brown, viscous oil. The fractions with the 

 lowest b. p. contained small quantities of methylheptenone, which 

 was separated in the form of a semicarbazone. Only after recrystallising 

 it three or four times from dilute alcohol the m. p. of this derivative 

 was found to be 134 to 13 5 . This circumstance, as well as the 

 fact that when the odour observed was not that characteristic of methyl- 

 heptenone, but rather reminded of a saturated fatty ketone, indicated 

 the presence of another, additional, ketone. The semicarbazone referred 

 to above, when mixed with that from the pure methylheptenone, 

 showed no depression of the melting point. 



In a fraction having the b. p. 75 to 82 (5 mm. press.) and the 

 opt. rot. -f- 6° 54', small quantities of d-menthone could be detected, 

 but only through the semicarbazone. Only when the oil mixed with it 

 had been removed from the semicarbazone solution by steam distillation, 

 the derivative could be obtained in the solid form. After repeated 

 recrystallisation from alcohol it melted at 178 to 181 and when 

 warmed with diluted acid it developed the unmistakable odour of 

 menthone. Efforts were also made, unfortunately without success, to 

 separate by means of the oxime larger quantities of menthone from 

 the fractions which preceded and succeeded the one referred to above, 

 and to reconstitute the ketone from them. It is therefore probable 

 that the somewhat pronounced odour of mint which attached to all 

 these fractions is ascribable to the presence of isopulegol. This 

 isopulegol obviously owed its existence to the action of acids upon 

 the citronellal. 



Further, in the portions of the oil boiling between 75 and 103 

 (5 mm. press.) we discovered an alcohol of a rose-like odour, which 

 was ascertained to be d-citronellol. For the purpose of identification 

 the fractions were treated in the well-known manner with phthalic 

 anhydride. The citronellol separated by saponification from the solution 

 of the sodium salt of the acid phthalic ester and distilled over with 

 water vapour, possessed the following constants: b. p. 93 to 95 

 (5 to 6 mm. press.), d 15 o 0,8732, <*& + 2 ° h'j n D20° 1,46288. The 

 silver salt prepared from the free acid phthalate, after being recrystallised 

 from benzene and methyl alcohol, showed the characteristic melting point 

 for this salt (125 ) and the theoretically required silver content: — 

 0,2774 g. sbst.: 0,0727 g. Ag. 

 Found: Calc. for C 18 H 21 Ag0 4 : 



Ag 26,21 % 26,23% 



