After the monomeric phenylacetaldehyde had been rectified once more, it boiled at 88° . 
(148 mm.) and the np»o was 1,52204. The combustion and the determination of the 
molecular weight in boiling chloroform afforded values which corresponded to the 
formula Cs;H,O. On continuing the distillation after the monomeric phenylacetaldehyde 
had been obtained, fractions boiling from 88 to 97° and from 97 to 210° (18 mm.) 
were collected, which, as the determination of their molecular weights showed, contained 
a polymeride in addition to monomeric phenylacetaldehyde. 
Various experiments were then made with regard to the polymerization of phenyl- 
acetaldehyde. In the presence of 23 p.c. sulphuric acid, phenylacetaldehyde, after 
several days’ standing, deposited odourless, colourless crystals melting at 155 tort50°,; 
for which the formula (Cs;H,O); was ascertained by combustion and determination of 
the molecular weight, so that we have here to deal with a trimeric phenylacetaldehyde. 
It is easily soluble in benzene, chloroform, and acetone, sparingly soluble in alcohol, 
ether and glacial acetic acid, and almost insoluble in water. 2,7 p.c. of trimeric 
phenylacetaldehyde dissolve in the monomeric one. As contrasted with the monomeride, 
the trimeride is indifferent to ammoniacal silver 
solution; it does not add any sodium disulphite, 
does not afford an oxime, remains colourless in (¢,H;-H,C-HC e CH-CH.:C, Hs 
the presence of alcoholic potash and does not 
give any reaction with magenta and sulphurous 
acid. It has therefore no properties of the alde- CH-CH,:C;,H 
hydes. It is an analogue of paraldehyde and 
must therefore be designated a _ triphenylpar- 
aldehyde. It distils unaltered in the vacuum of the cathode rays and is, at 13 mm. 
partly, at atmospherical pressure completely, depolymerized to monomeric aldehyde. 
With concentrated sulphuric acid, at room temperature as well as at — 80°, 
phenylacetaldehyde resinified. 
In the presence of 23 p.c. hydrochloric acid, the aldehyde became thick at first, 
and after about two days solidified, forming an amorphous, odourless polymeride, 
which no longer showed any properties of an aldehyde. 
When introducing dry hydrogen chloride into the aldehyde, it congealed to a 
viscid, sticky mass, which was not further investigated. 
Phenylacetaldehyde remained almost unchanged with anhydrous formic acid, even 
after two days’ standing. Glacial acetic acid and alcoholic solution of picric acid 
transformed it into a faintly yellow liquid. 
In the presence of 10 p.c. aqueous potash lye, a solid, odourless resin formed, a 
dimeride of phenylacetaldehyde. It is not volatile in an unaltered state, not even in 
an absolute vacuum, and far more easily depolymerizable than triphenylparaldehyde. 
It may therefore be called diphenylmetacetaldehyde in analogy with metaldehyde. The 
same body results through the action of piperidine on phenylacetaldehyde. 
In the dark and in ultraviolet light, phenylacetaldehyde polymerized without the 
addition of any catalysts at 21° to a thick oil, which was colourless and transparent, 
but not yet uniform. It contained monomeric phenylacetaldehyde and a viscid mass, 
which no longer gave the reaction with magenta and sulphurous acid, but on heating 
_Was split into the monomeric aldehyde. We have here to deal perhaps with a 
pentameride, (C;HsO);. Whereas the polymerization continues steadily in the dark, it 
apparently comes to a standstill on exposure to short-waved light, to go on all the 
quicker during the following dark period. There is therefore a photo-chemical after- 
effect. The stoppage during exposure may be explained by a state of equilibrium 
NOTES ON SCIENTIFIC RESEARCH. 93 
Triphenylparaldehyde. 
