NATURE 
49 
THURSDAY, NCVEMBER 16, 1882 
RECENT CHEMICAL SYNTHESES 
URING the Exhibition of Scientific Apparatus 
at South Kensington a few years ago one of the 
employed, of which the details have been sent to us by 
' Dr. Horbaczewski, is by heating urea with glycocoll at a 
most interesting exhibits was the first specimen of Urea | 
from Prof. Wohler. 
This substance and specimen may be said to be the 
; ae || 
first organic compound, or product of a living organism 
built up from its mineral elementary constituents, not 
certainly directly, but very nearly, by an ordinary chemical 
operation. 
The importance of this discuvery, made in 1828, was 
not, however, recognised for many years. 
and signification in a physiological sense were first per- 
ceived, but its formation is the earliest and best example ~ 
of an action that plays an important part, and is probably 
the most interesting question in modern organic che- 
mistry, namely, what the Germans call the “ Umlagerung” 
of the atoms in a molecule or “ intermolecular change.” 
Urea was obtained by Wohler by simply heating the | 
compound ammonium cyanate, NH,CNO, in contact | 
with water, whereby the arrangement of the atoms is so 
changed that the two nitrogen atoms become directly 
combined to hydrogen and only indirectly to the oxygen 
as shown in the chemical formula : 
\NH, 
So long ago as 1773 this substance was discovered as a 
constituent of urine, and since then its importance as a 
final stage in the retrogressive metamorphosis of the 
animal tissues, or of albumenoids, has been pretty fully 
worked out and recognised. 
Although albumin has not yet been directly oxidised to 
urea in the laboratory, the descent takes place in the 
animal economy through several stages, as for instance, 
Its importance | 
tyrosin, kreatin, xanthin, allantoin, uric acid, &c., probably 
by a simultaneous oxidation and hydration, or even re- 
duction. 
Several of these intermediate substances yield, | 
however, urea as a direct product of oxidation not only | 
when taken into the organism but when submitted to 
ordinary oxidising agents. Even substances like aspara- 
gine, leucine, and glycine, which are very near to albumin 
as products of retrogressive metamorphosis, may be con- 
sidered as preliminary stages in the splitting up and 
oxidation of the tissue substance into more simple com- 
pounds until a truly 7zeva/ character is arrived at. 
Although urea was synthesized from its mineral elements 
so long ago, it has until quite recently contributed com- 
paratively little to the syntheses of the more complex 
members of the class of bodies of which it is almost the 
final oxidation product. A great number of bodies have, 
however, been derived from urea by substitution. Pro- 
bably the most important synthesis obtained by the aid 
of this body since Wéhler prepared it from its mineral 
constituents, is the one just announced as having been 
made by Dr. Horbaczewski in the Vienna Chemical 
Institute. 
This chemist has succeeded in proceeding a step back- 
wards from urea to uric or lithic acid. The method 
VOL. XXVII.—No. 681 
temperature of 200°-230° C. in a metallic bath until the 
mass fuses and becomes brown and friable. 
Glycoco!l is amido acetic acid, CH,. NH,. COOH, and 
the reaction which takes place may perhaps be repre- 
sented :— 
CON H? + (CH, N Hy COOH),=C,N,H,O,+-OH +H, 
2 
The action as represented by this equation indicating 
conditions the reverse of those supposed to exist when 
uric acid is converted to urea. As to the structure of the 
group C;H,N,O, the simplest view is that of Medicus— 
It is somewhat remarkable that this reaction and synthesis 
has not been attempted or attained earlier, for the con- 
verse reaction, represented by the equation— 
| C;H,N,O, + 50H, = CH,.NH,. COOH + 3CO,+3NH, 
has been known for a considerable time. 
The same two substances have previously served as 
materials for an important synthesis, namely, that of 
hydantoin or hydantoic acid (Ber. Ber., p. 36). 
This synthesis is mostly important as giving a step 
| backwards towards that very complicated atomic group 
termed albumen. 
‘That this will eventually be arrived at is exceedingly 
probable, and in the near future, for an even more com- 
plicated substance than uric acid has also been built up 
and its structure or intermolecular constitution settled 
very conclusively by the method of synthesis employed 
by Erlenmeyer and Lipp. This substance is tyrosine, a 
product of the decomposition of albumen in the animal 
system, and also by putrefactive decomposition and by 
heating with alkalies or acids. 
The method is somewhat more complicated than the 
one employed by Dr. Horbaczewski. Starting with phen- 
ethyl-aldehyde they proceeded by conversion into phenyl- 
alanin and nitration to the amide compound— 
GH Mee 
6 4\.CH,—CH(NH,). COOH 
paranitrophenylalanine, a substance very similar, as will 
be seen on comparison of formulz in its nature to the 
amido acetic acid or glycocoll employed in the uric acid 
synthesis. On treating this body with nitrous acid the 
following reaction takes place :— 
NH, + NO?H 
COOH Sah Gap as 
CeHicy, : CH. NH). 
4OH 
+ CoHs\CH,. CH ..NH,.COOH. 
According to this method of building up, tyrosine is a 
para-hydroxy pheny] a alanine. 
Both reactions are similar in this respect: the end is 
attained by the splitting away of hydrogen from nitrogen 
groups N H, partly in the form of water. 
All these syntheses are really approaches to that of 
albumen, and in this connection some work lately done 
and published in brochure form by MM. Loew and 
Bokorny of Munich gains in importance. 
These investigators have proved the presence of alde- 
D 
