Improvements in the Manufacture of Vanillin.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Vanillin.
A communication from abroad by LA SOCIÉTÉ CHIMIQUE DES USINES DU
RHÔNE, anciennement GILLIARD P. MONNET ET CARTIER, of Lyons,
France, Manufacturers.
I, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn and Ellis of
55 and 56 Chancery Lane in the County of London, Chartered Patent Agents, do
hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of vanillin from proto-catechuic
aldehyde. By this invention the difficulty of the simultaneous production of
iso-vanillin in large proportions by the direct methylation of proto-catechuic
aldehyde is avoided.
According to this invention there is employed a new substituting agent leading
to the formation of two isomeric intermediate compounds, easily separated, one of
which may be converted into vanillin whilst the other is, by merely boiling with
water, reconverted into the original proto-catechuic aldehyde, and is therefore again
available for the manufacture of vanillin at very slight expense.
It has been found that by the regulated action of chloro-formic acid methyl
ester on the mono-potassium salt of proto-catechuic aldehyde, the methyl carboxylic
esters of proto-catechuic aldehyde are obtained. As the reaction between the two
bodies is somewhat violent it is advantageous to employ the potassium salt of proto-
catechuic aldehyde suspended in chloroform. And instead of the methyl ester of
chloro-formic acid other alkyl-esters (e.g. the ethyl ester) of halogenated formic
acid may be employed, in which case the corresponding alkyl (e.g. ethyl) carboxylic
esters of proto-catechuic aldehyde would result as intermediate products.
By the reaction, two isomeric substances are formed, one of which by treatment
with di-methyl sulphate in alkaline solution is converted into vanillin, whilst under
similar treatment the other yields iso-vanillio.
EXAMPLE.
1-76 kilos. mono-potassium salt of proto-catechuic aldehyde, well dried and finely
ground, is suspended in 5 kilos. chloroform and 1 kilo. chloro-formic acid methyl
ester is added. After a short time a violent reaction commences, which it is best
EXAMPLE
1-76 kilos. mono-potassium salt of proto-catechuic aldehyde, well dried and finely
ground, is suspended in 5 kilos. chloroform and 1 kilo, chloro-formic acid methyl
ester is added. After a short time a violent reaction commences, which it is best
to modify by well cooling the mixture, and atter standing ɔ or o hours at ordinary
temperature the reaction is complete. The chloroform solution is then filtered off,
and the residue extracted with a further 4 kilos. cold chloroform, whereby potassium
chloride and some proto-catechuic aldehyde are left behind. From the united
filtrates the chloroform is distilled off, and the residue, which solidifies on cooling,
is recrystallized from alcohol. One of the two isomeric substances remains
dissolved in the mother liquors, whilst the other, being difficultly soluble in cold
alcohol, separates in warty clusters of crystals.
The latter crystals, when obtained pure by repeated recrystallization from
alcohol, nelt at 98° to 99° C., are readily soluble in chloroform, benzene and
acetone, but with difficulty in cold ether, alcohol and ligroin. They are almost
insoluble in cold water, but dissolve in hot water and may be recrystallized

page_text: therefrom. By continued boiling with water this new compound is hydrolized and
protocatechuic aldehyde is regenerated in the solution.
For the preparation of vanillin from the purified ester melting at 98° to 99° C.
or its homologues, the ethyl ester etc., it is advisable to proceed as follows:-
1 kilo. of ester is dissolved in 15 litres alcohol and by cooling rapidly and
shaking continuously becomes suspended in the liquid in a very fine state of
division. There are then added 9 litres six per cent. alcoholic potash, and finally,
taking great care that the temperature does not rise above 15° C., 0.67 kilos.
dimethyl sulphate.
The liquid becomes slightly warm and is allowed to stand six hours to allow the
methylation to complete itself. After this the solution is acidified with dilute
sulphuric acid, and the alcohol distilled off. In the residue vanillin is found ready
formed and may be extracted with ether and purified in the usual way.
The other isomeric substance remaining in the alcoholic mother-liquors as above
explained and which hitherto has only been obtained as a yellowish oil, also
possesses a ready tendency to hydrolysis, and since by its methylation only
isovanillin is produced, it is re-converted into proto-catechuic aldehyde and may be
used over again in the process.
Dated this 22nd day of July 1896.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.
Improvements in the Manufacture of Vanillin.
A communication from abroad by LA SOCIÉTÉ CHIMIQUE DES USINES DU
RHÔNE, anciennement GILLIARD P. MONNET ET CARTIER, of Lyons,
France, Manufacturers.
I, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn and Ellis of
55 and 56 Chancery Lane, in the County of London, Chartered Patent Agents,
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 :-
This invention relates to the manufacture of vanillin from proto-catechuic
aldehyde. By this invention the difficulty of the simultaneous production of iso-
vanillin in large proportions by the direct methylation of proto-catechuic aldehyde
is avoided.
According to this invention there is employed a new substituting agent leading
to the formation of two isomeric intermediate compounds, easily separated, one of
which may be converted into vanillin whilst the other is by merely boiling with
water, reconverted into the original proto-catechuic aldehyde, and is therefore
again available for the manufacture of vanillin at very slight expense.
It has been found that by the regulated action of chloro-formic acid methyl ester
on the mono-potassium salt of proto-catechuic aldehyde, the methyl carboxylic
esters of proto-catechuic aldehyde are obtained. Instead of the potassium salt, the
sodium salt may also be used. As the reaction between the two bodies is somewhat
violent it is advantageous to employ the potassium salt of proto-catechuic aldehyde
suspended in chloroform. And instead of the methyl ester of chloro-formic acid
other alkyl-esters (e.g. the ethyl ester) of halogenated formic acid may be employed,
in which case the corresponding alkyl (eg. ethyl) carboxylic esters of proto-
catechuic aldehyde would result as intermediate products.

page_text: with di-methyl sulphate in alkaline solution is converted into vanillin, whilst under
similar treatment the other yields iso-vanillin.
EXAMPLE.
1.76 kilos. mono-potassium salt of proto-catechuic aldehyde, well dried and finely
ground, is suspended in 5 kilos. chloroform and 1 kilo. chloro-formic acid-methyl
ester is added. After a short time a violent reaction commences, which it is best to
modify by well cooling the mixture, and after standing 5 or 6 hours at ordinary
temperature the reaction is complete. The chloroform solution is then filtered off,
and the residue extracted with a further 4 kilos. cold chloroform, whereby potassium
chloride and some proto-catechuic aldehyde are left behind. From the united
filtrates the chloroform is distilled off, and the residue, which solidifies on cooling,
is recrystallized from alcohol. One of the two isomeric substances remains dissolved
in the mother liquors, whilst the other, being difficultly soluble in cold alcohol,
separates in warty clusters of crystals.
The latter crystals when obtained pure by repeated recrystallization from alcohol,
melt at 98° to 99° C., are readily soluble in chloroform, benzene and acetone, but
with difficulty in cold ether, alcohol and ligroin. They are almost insoluble in cold
water, but dissolve in hot water and may be recrystallized therefrom. By continued
boiling with water this new compound is bydrolized and protocatechuic aldehyde is
regenerated in the solution.
For the preparation of vanillin from the purified ester melting at 98° to 99° C.
or its homologues, the ethyl ester etc., it is advisable to proceed as follows:-
1 kilo. of ester is dissolved in 15 litres hot alcohol and by cooling rapidly an 1
shaking coutinuously becomes suspended in the liquid in a very fine state of
division. There are then added 9 litres 6 per cent. alcoholic potash, and finally,
taking great care that the temperature does not rise above 15° C., 0-67 kilos.
dimethyl sulphate.
The liquid becomes slightly warm and is allowed to stand six hours to allow the
methylation to complete itself. After this the solution is acidified with dilute
sulphuric acid, and the alcohol distilled off. In the residue vanillin is found ready
formed and may be extracted with ether and purified in the usual way.
The other isomeric substance remaining in the alcoholic mother liquors as above
explained and which hitherto has only been obtained as a yellowish oil, also
possesses a ready tendency to hydrolysis, and since by its methylation only
isovanillin is produced, it is re-converted into proto-catechuic aldehyde and may be
used over again in the process.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me and in what manner the same is to be performed,
I declare that what I claim in respect of the manufacture of vanillin is :-
1. The preparation of carboxylic esters, especially the methyl carboxylic ester,
of protocatechuic aldehyde by the action of the methyl or other ester of chloro-
formic acid upon the potassium or sodium salt of protocatechuic aldehyde,
substantially as described.
2. In the manufacture of vanillin, the methylation of the methyl carboxylic
ester of protocatechuic aldehyde which melts at 98° to 99° C. or of homologous
esters of the same constitution, by means of alcoholic potash and dimethyl sulphate
at ordinary temperatures, substantially as described.
3. The inanufacture of vanillin from the methyl carboxylic ester of proto-
catechuic aldehyde which melts at 98° to 99° C., or from homologous esters with
the same constitution, by methylation and subsequent hydrolysis of the methylated
product by means of dilute mineral acids, substantially as described.
4. As new products obtained in the manufacture of vanillin the carboxylic
esters of protocatechuic aldehydes, substantially as described.

page_text: 5. The manufacture of vanillin substantially in the manner hereinbefore
described.
Dated this 22nd day of April 1897
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.