A New Process for Producing Aromatic Aldehydes.
Year: 1897

page_text: [Communicated from abroad by THE FARBENFABRIKEN VORMALS FRIEDRICH BAYER & Co.,
of Elberfeld, Germany.]
A New Process for Producing Aromatic Aldehydes.
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Bream's Buildings, Chancery
Lane, in the County of London, Patent Agent, do hereby declare the nature of this
invention to be as follows:-
My foreign correspondents have found a new method of producing aldehydes of the
aromatic series, by first acting on aromatic hydrocarbons with a mixture of hydro-
chloric and hydrocyanic acid in the presence of aluminium chloride, and subsequently
treating the new bodies thus obtained with acids. The mixture of HCl and HCN,
acts in this process like the hypothetic chloride of the imido formic acid having the
formula
In the first stage, the hitherto unknown imide of benzaldehyde is produced, which
is transformed into benzaldehyde and ammonia by the action of acids in the second
stage of the reaction.
According to the researches of my foreign correspondents, the new process repre-
sents a general reaction, and applies not only to the aromatic hydrocarbons, but also to
phenol ethers and similar compounds.
In carrying out the new process, my foreign correspondents may proceed according
to the following example. The parts are by weight.

page_text: anisol and 10 parts of aluminium chloride, which mixture is heated the while at from
about 30 to 40 degrees Centigrade. The brownish-red colored mass obtained is then
poured on ice, and concentrated hydrochloric acid is added to the mixture. Subsequently,
the aldehyde set free, and the unchanged anisol, are distilled off by means of steam. In
order to separate the aldehyde from the anisol, the oily mixture obtained by the dis-
tillation is treated with sodium bisulphite, the aldehyde being dissolved, whilst anisol
remains undissolved. Finally, sodium carbonate is added to the solution, previously
filtered, of the bisulphite compound, and the pure aldehyde is distilled off from the
resulting mixture, with the aid of steam. The aldehyde thus obtained boils at
248 degrees Centigrade, and represents, according to the researches of my foreign
correspondents, the well-known anisaldehyde.
My foreign correspondents do not confine themselves to the particulars given in the
above example, as these can be varied within wide limits. Thus, for instance, instead
of gaseous hydrocyanic acid, the completed double compound of hydrocyanic and
hydrochloric acid can be employed; or salts of hydrocyanic acid, such as potassium
cyanide, mercury cyanide, or the like, can gradually be added to the mixture of the
phenol ether, or the like, with aluminium chloride, during the continuous introduction
of gaseous hydrochloric acid into the reaction mixture.
Instead of hydrochloric acid, the other haloid acids, such as hydrobromic acid, can
likewise be used in the new process.
Dated this 10th day of August 1897
NEWTON & SON,
Agents for the Applicant.
COMPLETE SPECIFICATION.
A New Process for Producing Aromatic Aldehydes.
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
My foreign correspondents have found a new method of producing aldehydes of
the aromatic series, by first acting on aromatic hydrocarbons with a mixture of
hydrochloric and hydrocyanic acid, in the presence of aluminium chloride, and
subsequently treating the new bodies thus obtained with acids. The mixture
of HCl and HCN acts, in this process, like the hypothetic chloride of the imido-
formic acid having the formula:

page_text: In the first stage, the hitherto unknown imide of benzaldehyde is produced
which is transformed into benzaldehyde and aminonia in the second stage of the
reaction.
According to the researches of my foreign correspondents, the new process
represents a general reaction, and applies not only to the aromatic hydrocarbons,
but also to phenol ethers and similar compounds.
In carrying out the new process, my foreign correspondents may proceed according
to the following examples. The parts are by weight :—
Into a mixture prepared from 30 parts of toluene and 40 parts of aluminium
chloride, dry gaseous hydrocyanic acid and hydrochloric acid are introduced at about
from 35 to 40 degrees Centigrade during several hours. The viscous reaction
product thus obtained is poured on ice. The mixture is then strongly acidulated
by means of hydrochloric acid, and the aldehyde is distilled therefrom with the aid
of steam. From the so-produced mixture of the aldehyde and unchanged toluene,
the pure aldehyde is separated as usual by means of sodium bisulphite.
According to the researches of my foreign correspondents, the aldehyde thus
formed is the well-known paratolylaldehyde boiling at 204 degees Centigrade.
My foreign correspondents do not confine themselves to the particulars given in
the above examples, as these can be varied within wide limits. Thus, for instance,
,the ingredients operated upon, as stated therein, can be replaced by other aromatic
hydrocarbons or phenolic ethers, and instead of gaseous hydrocyanic acid, the
completed double compound of hydrocyanic and hydrochloric acid can be employed;
or salts of hydrocyanic acid, such as potassium cyanide, mercury cyanide, or the
like, can gradually be added to the mixture of the phenol ether or the like with
aluminium chloride, during the continuous introduction of gaseous hydrochloric acid
into the reaction mixture.
In all these cases, probably in the first stage, intermediate products (imides of
aldehydes) are formed, which may be briefly termed "aldimides," and which are
transformed, in the second stage of the reaction, into the free aldehydes.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed (as communicated to me
from abroad), I declare that what I claim is :-
1. The process for producing aromatic aldehydes, which process consists in first,

page_text: allowing hydrochloric and hydrocyanic acid (or salts of the latter), or the completed
double compound of hydrochloric and hydrocyanic acid, to act in the presence of
aluminium chloride on aromatic hydrocarbons, phenolic ethers, or the like bodies,
and secondly splitting up the aldimides thus obtained by means of acids.
2. The new products obtainable as hereinbefore defined.
Dated thin 10th day of May 1808