Proceedings of the section of sciences - DWC - KNAW

- 220 -
'( 719 )
.the· said hydrocai'bons, these were not considered as identical in the
provisional communication. A second point of dift'erence 'was the
obtainment of a crystalline bromide from dihydro-ocimene. When,
afterwards, I repeated SEMMLER'S experiments, I found the boiling
point of dihydromYl'cene to be the Same as that of dihydro-ocimene,
whilst the othel' constants (as tal' as could be ascertained) agreed
with those of SEMMLER; I i'ound the following values:
sp. gl"15 nd' 17 b.p. at 761 mmo
0,7852 1,4514 166°-168°
Like SEMMLER, I found that myrcene and its hydro-product have
the same boiling point so that, probably, SEMMLER'S statement is
based on amistake; for othel' investigators also state 166° as being
the boilirlg point of myrcene.
The now probablc identity of the hydro-pl'oducts became a certainty
by the 'bl'omination of dihydromyrcene. As stated, dihydro-ocimene
had given me on bromination a cl'ystalline bromide; from the oil
obtained at th'st, it crystallises to the extent 'of 12-14%' Af ter
repeated cl'ystallisations from methyl alcohol it forms snow-white
crystals which melt, shal'ply, at 88°. Analysis and determination' of
moleculal' weight' pointed to toe compositiol1 OlOH18Br4' In most of
the ol'ganic solvents. this Qromide is readiJy soluble, but in methyl
alcohol only to the extent of 1,2 % ; on boiling with sodium hydroxide
and also wim-'si! ver oxide and water an oil smelling of peppermint
is obtained. From clihydl'omyl'cene I now obtained the same bromide.
The oil obtained by SEl\IMLER soon bolidifies when, aftel' being purified,
it is put away tó crystallise in a cool place; by applying a little
artifice I succeeded in instanUy inducing the crystallisation. The'
identity was proved by the fact that this bromide like all its mixtures
with dihyclro-ocimenetetrabromide, melted, sharply, at 815° and also
that the solubility of dihydro-ociÏnenebromide was practically not
aft'ected by addition of this substance. '
This now completely proves:
'i. that both ocimene and myrcene are aliphatic terpenes.
2. that the dihydroproducts of these terpen es are identicaL
•
From this it follows - and th is is probably of more impol'tance
still - that we may now deduce the stl'uctural formulae of ocimene
, and myrcene from the obtained data.
, As regards myrcehe, owing to its connection with citml and
" dipentene 1), it was -all'eady fairly certain that, like all aliphatic
1) POWER and KLEBERI 1. C.