Improvements in the Manufacture or Production of Vanillin.
Year: 1896

page_text: Date of Application, 1st Jan., 1896-Accepted, 29th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in the Manufacture or Production of Vanillin.
I, WILHELM MAJERT D.Ph. of Falkenberg near Grünau in the Kingdom of
Prussia, Chemist, 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 :-
A method is described in the Specification of the German Letters Patent
No. 82924 for the manufacture or production of vanillin. According to that
method, the hydroxyl group of the eugenol is converted into an ester by an easily
removable aromatic alcohol acid, so that the new substance contains a free
carboxyl group by means of which it produces soluble salts which can be oxidised
in solution by neutral or alkaline oxidising agents.
It was important to know also such derivatives of the isocugenol as were not
precipitated by acids, in order that they may be oxidised in solution by acid
oxidising agents.
According to my invention, I replace the carboxyl group by a sulpho group,
and have found that chloronitrobenzol-sulpho-acid 1. 2. 4., or bromonitrobenzol-
sulpho-acid 1. 2. 4. are suitable for my purpose. If the sodium salts of these
acids be combined with isoeugenol-sodium, the sodium salt of isoeugenolphenyl-
ethernitro-sulpho-acid is produced, according to the following equation :-
The sodium salt is readily soluble in water, and strong acids produce no
precipitation from its diluted solution. Oxidation by suitable known means
converts it to vanillinphenylethernitro-sulpho-acid, which, when boiled with soda
lye becomes decomposed into the sodium salts of vanillin and nitrophenol-sulpho-
acid respectively.
I will illustrate in what manner my invention may be carried into effect.

page_text: 2. OXIDATION OF THE ISOEUGENOLPHENYLETHERNITRO-SULPHO-ACID.
For this purpose it is advantageous if no free material acid be present, as this
influences the propenyl group.
I boil, under an inverted condenser a solution of-
37.6 kilos. of the sodium salt of isoeugenolphenylethernitro-sulpho acid, and
32 kilos. of sodium bichromate in
600 litres of water,
and pour into it gradually during from 12 to 15 hours, 445 kilos. of ten per cent.
solution of sulphuric acid. Thereafter the liquid is still kept boiling for about
6 hours and is made alkaline by the addition of soda. By filtering off the
chromium hydrate, I obtain the sodium salt of vanillin-phenylethernitro-sulpho-
acid, and sodium sulphate in solution.
3. SEPARATION OF THE VANILLIN FROM THE VANILLIN
PHENYLETHERNITRO-SULPIIO-ACID.
To the solution obtained as described in the preceding stage of the process,
I add 10 kilos. of sodium hydrate and boil together until the yellow colour soon
produced by the precipitation of the sodium salt of nitrophenol-sulpho-acid ceases
to increase in intensity. I then acidify with dilute sulphuric acid and extract the
vanillin by means of ether as is well understood. The ethereal extract is then
shaken with an aqueous solution of sodium bisulphite, when the vanillin passes
into the solution as a double combination with bisulphite of soda. The watery
solution, separated from the ether, is then boiled with as much hydrochloric
or sulphuric acid as may be necessary to expel the sulphurous acid. After this,
the free vanillin is removed from the solution by means of ether which is evaporated
and the residual vanillin is crystallised out with benzol.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The hereinbefore described process for the manufacture or production of vanillin,
substantially as and by the means set forth.
Dated this 31st day of December AD 1895
W. E. HEYS & SON,
Agents for the Applicant.