— 135 — 



Isopulegone. The treatment of isopulegone with magnesium 

 methyl iodide and the conversion of the resulting 3 -methyl isopulegol 

 into 3 -methyl zl 2 ' 8 ^-menthadiene, to which reference has already been 

 made in our last Report 1 ), has been the subject of a detailed paper by 

 A. Ebert 2 ). For particulars as to constants, as well as for details 

 concerning the mode of the splitting-off of water (which was carried out 

 according to various methods), we refer to the original paper. 



Umbellulone. F. W. Semmler 3 ) has recently entered the lists 

 once more in the controversy which is being carried on between 

 Tut in and himself on the constitution of umbellulone; his object 

 on this occasion being to controvert Tu tin's objections, which were 

 discussed in our recent Reports 4 ). Tutin having maintained that 

 Semmler's arguments referred in reality to a foreign body which was 

 mixed with the umbellulone, the latter repeated his experiments, using 

 for that purpose an umbellulone which had been regenerated from the 

 semicarbazide compound. Umbellulone, obtained by fractionating an 

 oil distilled by us, was found to possess the following constants: b. p. 92 

 to 94 at 10 mm. press., d 20 ° 0,950, n D 1,4872, « D — 37°3°'- In 

 addition to the semicarbazide-semicarbazone which had already been 

 described by another investigator (and which Semmler now showed 

 to possess a m. p. above 200 ), the author was also able to prepare 

 the normal mono-semicarbazone with a m. p. between 240 and 243 . 

 The umbellulone regenerated from the last-named product by decom- 

 position with dilute sulphuric acid gave the following constants: b. p. 92,5 

 to 93 at 10 mm. press., d 20 o 0,950, n D 1,48325, « D — 36°3°'- The 

 preparation obtained from the semicarbazide-semicarbazone showed the 

 following constants: b. p. 92 to 94 at 10 mm. press., n D 1,4825, 

 «d — 37°. For /?-dihydro umbellulol obtained from the regenerated 

 umbellulone the following constants were determined: b. p. 88 to 92 ° 

 at 10 mm. press., d 2 (P 0,927, n D 1,4696, a D — 2 7°45'; f° r /J-dihydro- 

 umbellulone: b. p. 84 to 86° at 10 mm. press., d2o° 0,925, n D 1,4616, 

 a D — 30 . The benzylidene-compound prepared from the last-named, 

 when oxidised with permanganate in acetone solution, yielded (as 

 before) homotanacetone dicarboxylic acid (m. p. 14 7 ). Hence the 

 assertion of Tutin, that Semmler's benzylidene compound was not 

 derived from /Wihydro-umbellulone, falls to the ground. Without doubt 

 the quantitative conversion into thymol (m. p. 5 2°, b. p. ni° at 

 10 mm. press., d2o° 0,977, n D i y § 2 148, « D +o°) by prolonged heating 



x ) Report November 1908, 186. 



2 ) Zeitschr. d. allg. oesterr. Apoth. Ver. 46 (1908), 545, 561, 573, 589. 



8 ) Berl. Berichte 41 (1908), 3988. 



4 ) Report April 1908, 108; November 1908, 126, 



