Improvements in the Manufacture or Production of Cinnamic Aldehyde.
Year: 1896

page_text: Date of Application, 11th May, 1896
Complete Specification Left, 11th Feb., 1897-Accepted, 27th Mar., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture or Production of Cinnamic
Aldehyde.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me by C. F. Boehringer & Soehne of Waldhof, near Mannheim, in
the Empire of Germany) to be as follows: -
The synthetical production of cinnamic aldehyde from benzaldehyde and acet-
aldehyde was effected by Peine (Ber. der Deutsch. Chem. Ges. 1884, 17, 2109).
He adopted for the purpose Claissen's method of condensation employing very
dilute aqueous caustic soda as the condensing agent.
In order to complete the condensation it is necessary to heat the mass during
8-10 days at 30° Centigrade. while well agitating it. As is generally known,
however, an application of this method is not practicable as apart from the fact
that very large volumes of liquid must be manipulated, the yield of pure cinnamic
aldehyde so obtained is very small, chiefly on account of the fact that the prolonged
action of the alkali, although proceeding at a moderate temperature converts the
cinnamic aldehyde to a large extent into a viscous reddish-yellow resin.
My foreign correspondents have found that by employing highly concentrated
caustic alkali as condensing agent and by reducing the temperature during the
operation through the application of ice-water, or a freezing mixture, the conversion
of the aldehyde into resin may be avoided, and the synthetical production of
cinnamic aldehyde becomes a process of technical value.
According to the method according to this invention the condensation is complete
in a short time, and yields up to 80 per cent. of the theoretical amount of cinnamic
aldehyde. In order to mix the aldehydes and alkali more completely it is
advantageous to employ alcohol (methylic or ethylic alcohol) as a solvent.
The following example serves to assist in explaining the invention, the parts
being by weight-
5 parts of benzaldehyde and 4 parts of acetaldehyde are dissolved in 10 parts of
fine spirit and cooled to- 10° Centigrade by means of a freezing mixture. Within
5 or 10 minutes, 10 parts of 25-30 per cent. caustic soda solution are added to this
solution which is agitated meanwhile, the alkali having been previously cooled by
a freezing mixture.
After a short time the solution becomes clear, and having remained for from
15 to 20 minutes in the freezing mixture the mixture is diluted with water, the
precipitated oil extracted with ether, and the residue left on evaporating the
ether distilled in a vacuum, in this way pure cinnamic aldehyde distills over as a
golden yellow liquid at 120-125° Centigrade under a pressure of 11 millimetres.
The phenylhydrazone prepared from it melts at 168° Centigrade.
Dated this 11th day of Mar 1906
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture or Production of Cinnamic
Aldehyde.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by C. F. Boehringer & Suehue, of Waldhof, near
Mannheim, in the Empire of Germany) and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement :-
The synthetical production of cinnamic aldehyde from benzaldehyde and acet-
aldehyde was effected by Peine (Ber. der Deutsch. Chem. Ges. 1884, 17, 2109).
He adopted for the purpose Claissen's method of condensation, employing very
dilute aqueous caustic soda as the condensing agent.
In order to complete the condensation it is necessary to heat the mass for from
8 to 10 days at 30° Centigrade while well agitating it. As is generally known,
however, an application of this method is not practicable, as apart from the fact
that very large volumes of liquid must be manipulated, the yield of pure cinnamic
aldehyde so obtained is very small, chiefly on account of the fact that the prolonged
action of the alkali, although proceeding at a moderate temperature, converts the
cinnamic aldehyde to a large extent into a viscous reddish-yellow resin.
My foreign correspondents have found that by employing highly concentrated
caustic alkali as condensing agent, and by reducing the temperature during the
operation by the application of ice-water or a freezing mixture, the conversion of
the aldehyde into resin may be avoided, and the synthetical production of cinnamic
aldehyde becomes a process of technical value.
By the method according to this invention the condensation is complete in a
short time, and yields up to 80 per cent. of the theoretical amount of cinnamic
aldehyde. In order to mix the aldehydes and alkali more completely it is
advantageous to employ alcohol (methylic or ethylic alcohol) as a solvent.
The following example serves to assist in explaining the invention and the
manner in which it can be performed, the parts being by weight.
5 parts of benzaldehyde and 4 parts of acetaldehyde are dissolved in 10 parts of
fine spirit and cooled to -10° Centigrade by means of a freezing mixture. Within
5 or 10 minutes, 10 parts of 25-30 per cent. caustic soda solution are added to this
solution which is agitated meanwhile, the alkali having been previously cooled by
a freezing mixture.
After a short time the solution becomes clear, and having remained for from
15 to 20 minutes in the freezing mixture the mixture is diluted with water, the
precipitated oil extracted with ether, and the residue left ou evaporating the ether
distilled in a vacuum. In this way pure cinnamic aldehyde distils over as a golden
yellow liquid at 120°-125° Centigrade under a pressure of 11 millimetres.
The phenylbydrazone prepared from it melts at 168° Centigrade.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The manufacture or production of cinnamic aldehyde by the condensation of
benzaldehyde and acetaldehyde by means of a concentrated alkaline solution at a
low temperature as hereinbefore explained in the presence of alcohol or not.

page_text: 2. The manufacture or production of cinnamic aldehyde in the manner set out
in the foregoing example.
Dated this 11th day of February 1897.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.