. : 
_ 232, 243, 287. — *) We would mention that benzyl alcohol only smells of bitter almonds if itis” 
Gr the purpose, owing ‘to the (eke of sufficiently expressive words in comm lige pa 
Henning promises additional publications \ on the same subject, to which oc 
_ may look forward with interest. 
R. Marchand?) calls gitention to some relations between constitution and odour of 
organic substances. With a view to the preparation of new aromatics, it is of the 
_ greatest interest to get to know the action of the single groups, and there has been, in. 
consequence, no scarcity of experiments in order to study their odoriferous influence. 
“The results were rather disappointing, as the so-called odoriferous groups recur in. 
widely different aromatics and there, apparently without any rules, give rise to the most — a 
oe one recognizes 
‘that, apparently, it can produce any smell, such as in citral, benzaldehyde, octaldehyde, 
and phenylacetaldehyde. The odours of these aldehydes do not show the slightest : 
relation to one another. It is almost impossible to establish any rules for the odoriferous _ 
action by dividing the bodies into alcohols, aldehydes, ketones, &§c. One must, in con- — 
sequence, come to the conclusion that the influence of said group is quite accidental — 
as regards smell. It is the nature of the nucleus or main group which has determinating _ 
influence on the smell. Furthermore, the position of the group concerned in the chief 
molecule must be taken notice of. How little the group and how much the position © 
produces the smell can best be traced in the benzene derivatives. The group only 
shades the odour but keeps it in the same class. eS 
The first rule found is that the introduction of an odoriphorous group always leads = 
to the bitter almond class. The group itself only gives variations of one and the same — 
class of odour, so that non-experts always designate them as being like bitter almond, ‘s 
varied odours. When taking into consideration e. g. the group - ‘Cc 
which is the case with e ‘\.NO, (nitrobenzene), Ces CHO (benzaldehyde), 
Ne 
« »CH.OH (benzyl alcohol) and < >COCHs (acetophenone)’). The substitution. 
of a hydroxyl group in para position leads to a reduction of the smell or éven to a 
inodorousness. If the first group has a mobile atom of hydrogen, the body becomes “a 
inodorous on introduction of the hydroxyl group in para position. Such is the vie 
case with p-hydroxybenzaldehyde, quinol and. p-hydroxybenzyl alcohol. By fixing the 
hydrogen in the hydroxyl group, strongly odoriferous bodies are generally formed 
such as anisaldehyde (aubépine) from p-hydroxybenzaldehyde, methyl quinol fro 
quinol, 8c. The same is attained’ if between the hydrogen atoms in para positio 
a third group is introduced, which does not contain any hydroxyl hydrogen. Th 
insertion of a further hydroxyl group does not interfere with the inodorousne 
Protocatechualdehyde (3,4-dihydroxybenzaldehyde) is odourless. If the hydroxyl gro 
in meta position is fixed by means of methyl, vanillin results. Heliotropin, allie 
odour with vanillin, proves that the principal matter is not the methoxyl group, 
1) Zeitschr. f. Psychologie 78 (1915), 161; 74 (1916), 305; 75 (1916), 177. — %) Deutsche Parf.-Z1 
ized, i.e. if it contains benzaldehyde. Pure benzyl alcohol does not show this ade? becee e 
