is 
—S a = =) ee hh 
NOTES ON SCIENTIFIC RESEARCH. 73 
its methyl ester. The reaction is slower at ordinary pressure. Ethyl cinnamate forms 
ethyl phenylpropionate (b. p. 127° at 15 mm.), if hydrogenated under pressure. The 
authors obtained p-methoxypropylbenzene (b. p. 209 to 211° at 761 mm.) from anethole, 
dihydroeugenol and octohydroeugenol (phenylurethane, m. p. 272°) from eugenol, dihy- 
drosafrole from safrole, (b. p. 238 to 230°) and dihydroeugenol from isoeugenol. 
Action of ozone on organic compounds. 
C. Harries and his collaborators, as well as other scientists, have shown by their 
experiments that the ozone method is of great service in determining the constitution 
of organic compounds’). Harries?) has now published a summary of the action of 
ozone on organic compounds, in which he discusses the ozone method in general 
and reports on his most recent experiences in this realm. 
In first place, Harries calls attention to the advantages and disadvantages of the 
ozone method, prompted to do so by the assertion of a fellow-chemist that it was not 
by far so applicable as the catalytic reduction method. There is a certain similarity 
between the two, for in either case, besides hydrogen and oxygen, nothing is introduced 
that might make the isolation of the reaction products more difficult. Furthermore, 
wherever a body can be hydrogenated catalytically, ozone derivatives may likewise 
be obtained from it, but not vice versa. All endeavours have failed, for instance, to 
hydrogenate india-rubber, although the ozonization takes place easily. A serious 
advantage of the catalytic hydrogenation method consists in its being extremely 
convenient and cheap, whereas the ozonization apparatus is expensive. In addition, 
it is more difficult to handle the ozonides, special experiments being necessary for 
every isolated case. In Harries’ opinion, the essential value of the hydrogenation 
method lies only in that it permits of preparing new bodies direct from the unsaturated 
compounds, whereas nothing definite is ascertained regarding the position of the double 
linking. He lays stress on some unconditional advantages of the ozonization method, 
pointing out that the position of the double linking can easily be ascertained from 
the character of the ozonides and by isolating their decomposition products. The 
ozonization method is not only applicable in a more general way, but it penetrates 
also far deeper into the nature of the compound. 
A difficulty, which in the course of time has made itself felt often enough as 
inconvenient, consists in that certain bodies, such as terpene alcohols and unsaturated 
phenols, do not yield uniform normal ozonides. However, if very dilute solutions are 
used and ozone which has previously been washed in a 5 p.c.*caustic soda lye and 
concentrated sulphuric acid, the normal ozonides are obtained in almost every case. 
Concentrated ozone may split off water from cholesterol and terpineol. From cyclic 
hydrogenated hydrocarbons, ozonides are sometimes obtained, the composition of which 
lies between that of the normal ones (O;) and the oxozonides (QO,). With proper 
treatment, one now almost invariably succeeds in preparing what is intended, i. e. either 
#the normal ozonide or the oxozonide. 
A second difficulty, which has not yet been removed completely, consists in that 
the decomposition of the ozonides with water and glacial acetic acid may give rise 
to very stable peroxides of the aldehydes or ketones, the existence of which was 
altogether unknown before the ozone reaction. 
1) Comp. e. g. Reports April 1906, 98; April 1907, 115; April 1908, 178; October 1909, 188; October 
1910, 194; October 1912, 145. — 7) Liebigs Annaien 410 (1915), 1 
