for Use in the Manufacture of Vanillin.
Year: 1886

page_text: for Use in the Manufacture of Vanillin.
I, LUDWIG LANDSBERG, of 52 Frankfurter Strasse, Offenbach on the Main, in
the German Empire, Doctor of Science, 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, that is to say:―
The material used in the first instance is the m-chloro-p-nitro toluene which is
first converted into m-chloro-p-nitro benzaldehyd.
For this purpose the m-chloro-p-nitro toluene is converted into chloro nitro
benzylchloride or chloronitro benzylbromide from which, after treatment with
nitrate of lead, or of copper, the m-chlor-p-nitro benzaldehyd is obtained. This
aldehyd can also be obtained from chloro-nitro benzylbromide according to the
methods used for converting benzylchloride into benzaldehyd.
The following process produces a good result:
m-chloro-p-nitro toluene is heated under pressure with a molecule of bromine at
a temperature of from 130° to 140° C, until the whole of the bromine is used up.
The resulting m-chloro-p nitro benzylbromide is washed in water and boiled with
a solution of nitrate of lead. When all the chloro-nitro benzylbromide is converted,
which takes place after boiling for about a couple of days, the in-chloro-p-nitro
benzaldehyd formed, separates from the lead solution and from various lead salts, and
can be purified by crystallization preferably from hot petroleum ether. It appears
then in white and shiny needles and melts at a temperature of from 78° to 79° C.
This substance forms with sulphite of soda a soluble combination and produces
with Phenyl-hydrazin a red coloured product of condensation. The m-chloro-p-
nitro benzaldehyd exchanges, when treated with alkali methylate or with alkali-
hydroxyde in a solution of methylalcohol, its chlorine for a methoxyl group and is
converted into m-methoxy-p-nitro benzaldehyd.
To a solution of m-chloro-p-nitro benzaldehyd in methylalcohol is added a
molecule of sodium methylate or a molecule of potassium hydroxyde or of sodium
hydroxide likewise dissolved in methylalcohol. The mixture is heated to boiling
point until the alkaline reaction has ceased. The solution contains then the
m-methoxy-p-nitrobenzaldehyd which is obtained separately by distilling the
methylalcohol off. This aldehyd can also be obtained from m-chloro-p-nitro-
benzaldehyd in such a manner that the chlorine is first replaced by the hydroxyl

page_text: group and the resulting m-oxy-p-nitrobenzaldehyd is converted into its methyl-
ether. For the preparation of m-oxy-p-nitrobenzaldehyd, the m-chloro-p-nitro-
benzaldehyd is heated to a temperature of from 130° to 150° C, with an aqueous
solution of an alkaline carbonate, or it may be boiled for some period of time with
two molecules of alkali-hydroxyde. The resulting m-oxy-p-nitrobenzaldehyd can be
converted into m-methoxy-p-nitrobenzaldehyd by any known methods.
The m-methoxy-p-nitrobenzaldehyd obtained by the above described two pro-
cesses crystallizes from hot water in small white needles melting at 62° C. It
produces when heated with acetate of soda and anhydrousacetic acid m-methoxy-p-
nitrocinnamic acid.
The m-methoxy-p-nitrobenzaldehyd can be employed in the manufacture of
vanillin according to any known process.
Having now described my Invention and in what manner the same may be
carried into effect I declare that what I claim is:
1. The preparation of m-chloro-p-nitrobenzaldehyd by the conversion of
m-chloro-p-nitrotoluene into m-chloro-p-nitrobenzylchloride or into m-chloro-p-
nitrobenzylbromide and boiling these products with a solution of nitrate of lead or
of copper, substantially as described.
2. The preparation of m-methoxy-p-nitrobenzaldehyd by heating m-chloro-p-
nitrobenzaldehyd with alkali-methylate or alkali-hydroxydes dissolved in methyl-
alcohol, or by the conversion of m-chloro-p-nitrobenzaldehyde through heating
with an aqueous solution of caustic or carbonated alkalies into in-oxy-p-nitro-
benzaldehyd which is finally converted into in-methoxy-p-nitrobenzaldehyd by
treatment with methyl, substantially as described.
ERNEST DE PASS, Fel. Inst. P.A.,
Agent for the Applicant.