Improvements in the Manufacture of Aromatio Sulphuryl Derivatives of Protocatechuic Aldehyde and their Conversion into Vanillin
Year: 1893

page_text: Date of Application, 15th Dec., 1893
Complete Specification Left, 17th Sept., 1894-Accepted, 20th Oct.,
1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Aromatio
Sulphuryl
Derivatives of Protocatechuic Aldehyde and their Conversion
into Vanillin.
I, SYDNEY PITT, of Sutton in the County of Surrey, Gentleman, (a
communication to me from abroad by The Chemische Fabrik auf Actien vorm.
E. Schering of 170 Müllerstrasse, Berlin) do hereby declare the nature of this
invention to be as follows:-
in the combination of the following three processes:

page_text: together with one molecular proportion of protocatechuic aldehyde and one
molecular proportion of an alkaline hydroxide, or an equivalent quantity of an
alkaline carbonate, either in alcoholic or aqueous solution, warm or at ordinary
temperatures; or the solid mono-metallic salt of protocatechuic aldehyde is
brought together with the sulpho-halide in the presence of an indifferent diluent,
as common salt, toluol, chloroform etc. Besides the p-sulpho compound of
protocatechuic aldehyde, small quantities of a di-sulpho derivative and according
to the conditions smaller or larger quantities of a m-sulpho derivative are formed,
which can easily be separated from the p-sulpho compound by crystallisation or by
conversion into a salt.
PREPARATION OF P-BENZENESULPHOPROTOCATECHUIC ALDEHYDE.
Example A. To an ice-cold solution of 400 grammes protocatechuic aldehyde in
10 litres water a solution of 510 grammes benzenesulphochloride in 5 litres ether are
added. A solution of 730 c.c. caustic soda solution, containing 15 per cent. sodium
hydroxide and diluted with 5 litres of water, is then slowly run in with constant
and energetic stirring. After the odour of the sulphochloride has disappeared a
like quantity of caustic soda solution is added, whereby the p-benzene-sulpho-
protocatechuic aldehyde that has been formed is brought into the alkaline
solution; the ethereal layer contains small quantities of the di-sulpho product,
from which protocatechuic aldehyde can be easily regenerated. The alkaline
liquors are acidified with hydrochloric acid, whereby the p-benzenesulpho-
protocatechuic aldehyde is separated as an oil that gradually becomes crystalline.
Under these conditions only very small quantities of m-benzenesulphoprotocatechuic
aldehyde are formed and these can be separated by crystallising the crude product
out of toluene. Or a still more advantageous procedure is to add an excess of
saturated baryta water to the alcoholic solution of the crude product, remove the
precipitated barium salt of p-benzenesulphoprotocatechuic aldehyde and decompose
it with acid. The barium salt of m-benzenesulphoprotocatechuic aldehyde is
much more easily soluble and separates out of the aqueous solution much more
slowly.
The p-benzenesulphoprotocatechuic aldehyde crystallises from toluene in
radiating groups of acicular crystals, which melt about 110° C. The isomeric
m-product melts about 147° C.
Example B. To a solution of 60 grammes protocatechuic aldehyde in
300 grammes alcohol and 120 c.c. alcoholic potash containing 20 per cent. by
volume of potassium hydroxide, 78 grammes benzenesulphochloride are gradually
added, care being taken to keep the mixture cool. The residue remaining after
evaporation of the alcohol is taken up with dilute caustic soda solution and the
solution then shaken with ether in order to remove a sinal quantity of
di-benzenesulpho-protocatechuic aldehyde. The mono-benzenesulpho-protocatechuic
aldehyde is then precipitated from the alkaline solution with acids as an oil that
gradually crystallises, and is further worked up as in Example A. Under these
conditions more of the isomeric m-product is obtained than in Example A.
PREPARATION OF P. TOLUENESULPHOPROTOCATECHUIC ALDEhyde.
This is prepared in the way above described. It crystallises from toluene in
warty crystals that melt about 118° C.
In the same way the derivatives of o- and m-toluene sulphonic acids, as well as
of a- and -naphtalenesulphonic acids can be obtained.
In regard to the second operation, the methylation of aromatic derivatives of
sulphoprotocatechuic aldehyde, the methylation of p-benzenesulphoprotocatechuic
aldehyde is effected, for example, in the following manner. To a solution of
40 grammes benzenesulphoprotocatechuic aldehyde and 30 grammes methyl-iodide in
70 grammies methyl alcohol, 40 c.c. alcoholic potash solution, containing 20 per cent.

page_text: caustic potash by volume, is added. The mixture is either allowed to stand for
a long time at a moderature temperature or heated a short time under pressure
in the water bath. After evaporation of the alcohol the residual oil is taken up
with ether, the ethereal solution shaken with caustic soda solution to remove traces
of unaltered benzenesulphoprotocatechuic aldehyde. On distilling off the ether
from the ethereal layer the benzenesulpho vanillin remains behind as a thick oil
which quickly solidifies.
The methylation of p-toluenesulphoprotocatechuic aldehyde is carried out in the
same way with methyl iodide or with a salt of methylsulphuric acid. The
p-toluenesulphovanillin crystallises from alcohol in thick needles which melt
about 115° C.
In the third operation, the splitting off of the vanillin from the sulpho derivatives
is effected by means of known saponification methods.
Example: 40 grammes benzenesulphovanillin are boiled with 1 litre dilute
caustic soda solution under a return condenser until the solution is perfectly clear.
After acidifying the vanillin is isolated in the ordinary way.
Dated this 15th day of December 1893.
SYDNEY PITT.-
.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Aromatic Sulphuryl
Derivatives of Protocatechuic Aldehyde and their Conversion
into Vanillin.
I, SYDNEY PITT, of Sutton in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by The Chemische Fabrik auf Actien vorm. E. Schering
of 170 Müllerstrasse Berlin), 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 :-
According to this invention, in protocatechuic aldehyde for the hydrogen of the
hydroxyl group, which is in the para position to the COH group there is
substituted a group that can be easily removed (again, for instance the benzene-
sulpho, the toluene-sulpho group and the like; that is to say, compounds of the
type of p. benzene-sulpho-protocatechuic aldehyde are first obtained; these are
subsequently methylated and submitted to a splitting operation.
The method consists in the combination of the following three processes:
1. Preparation of compounds of the type of p. benzenesulphoprotocatechuic

page_text: CH-OCH, (2) + 2 NaHO = C¸H,—OCH¸ (2) + NaSO,R
\CHO˚ (4)
CHO (4)
+ H₂O
The first operation, the preparation of aromatic para-sulpho derivatives of
protocatechuic aldehyde is effected in the following manner. One molecular
proportion of an aromatic sulpho-halide (for instance benzenesulphochloride, p-,
m- or o-toluene-sulphochloride, a- or B-naphtalene-sulphochloride etc.) is brought
together with one molecular proportion of protocatechuic aldehyde and one
molecular proportion of an alkaline hydroxide or alkaline earth hydroxide or an
equivalent quantity of an alkaline carbonate, or phosphate and the like either in
alcoholic or aqueous solution, warm or at ordinary temperatures: or the solid mono-
metallic salt of protocatechic aldehyde is brought together with the sulpho halide
in the presence of an indifferent diluent, as common salt, toluol, chloroform etc.
Besides the p-sulpho compound of protocatechuic aldehyde, small quantities of a
di-sulpho derivative and according to the conditions smaller or larger quantities of
a m-sulpho derivative are formed, which can easily be separated from the p-sulpho
compound by crystallization or by conversion into a salt, preferably into the
barium salt.
PREPARATION OF P-BENZENESULPHOPROTOCATECHUIC ALDEHYDE.
Example A. To an ice-cold solution of 400 grammes protocatechuic aldehyde
in 10 litres water a solution of 510 grammes benzene sulphochloride in 5 litres ether
are added.
A solution of 730 c.c. caustic soda solution, containing 15 per cent.
sodium hydroxide and diluted with 5 litres of water, is then slowly run in with constant
and energetic stirring. After the odour of the sulpho-chloride has disappeared
a like quantity of caustic soda solution is added, whereby the p-benzene sulpho
protocatechuic aldehyde that has been formed is brought into the alkaline solution ;
the ethereal layer contains small quantities of the di-sulpho product from which
protocatechuic aldehyde can be easily regenerated. The alkaline liquors are
acidified with hydrochloric acid, whereby the p-beuzenesulphoprotocatechuic
aldehyde is separated as an oil that gradually becomes crystalline. Under these
conditions only very small quantities of m-benzenesulphoprotocatechuic aldehyde
are formed and these can be separated by crystallising the crude product out of
toluene. Or a still more advantageous procedure is to add an excess of saturated
baryta water to the alcoholic solution of the crude product, remove the precipitated
barium salt of p-benzenesulphoprotocatechuic aldehyde and decoinpose it with acid..
The barium salt of m-benzenesulphoprotocatechuic aldehyde is much more easily
soluble and separates out of the aqueous solution much more slowly.
The p-benzenesulphoprotocatechuic aldehyde crystallises from toluene in radiating
groups of acicular crystals, which melt about 110° C. The isomeric m-product
melts about 147° C.

page_text: Example B. To a solution of 60 grammes protocatechuic aldehyde in
300 grammes alcohol and 120 c.e. alcoholic potash containing 20 per cent. by
volume of potassium hydroxide, 78 grammes benzenesulphochloride are gradually
added, care being taken to keep the mixture cool. The residue remaining after
evaporation of the alcohol is taken up with dilute caustic soda solution and the
solution then shaken with ether in order to remove a small quantity of di-
benzenesulpho-protocatechuic aldehyde. The mono-benzenesulpho-protocatechuic
aldehyde is then precipitated from the alkaline solution with acids as an oil that
gradually crystallizes, and is further worked up as in Example A. Under these.
conditions more of the isomeric m-product is obtained than in Example A.
PREPARATION OF P. TOLUENESULPHOPROTOCATECHUIC ALDEHYDE.
This is prepared in the way above described.
warty crystals that melt about 118° C.
It crystallises from toluene in
In the same way the derivatives of o- and m-toluene sulphonic acids, as well as
of a- and B-naphtalenesulphonic acids can be obtained.
In regard to the second operation, the methylation of aromatic derivatives of
sulphoprotocatechuic aldehyde, the methylation of p-benzenesulphoprotocatechuic
aldehyde is effected, for example, in the following manner. To a solution of 40 grammes
benzenesulphoprotocatechuic aldehyde and 30 grammes methyl-iodide in 80 grammes
methyl alcohol, 40 c.c. alcoholic potash solution, containing 20 per cent. caustic
potash by volume is added or preferably the equivalent quantity of sodium
methylate. The mixture is either allowed to stand for a long time at a moderate
temperature or heated a short time under pressure in the water bath. After
evaporation of the alcohol the residual oil is taken up with ether, the ethereal
solution shaken with caustic soda solution to remove traces of unaltered benzene-
sulphoprotocatechuic aldehyde. On distilling off the ether from the ethereal layer
the benzenesulphovanillin remains behind as a thick oil which quickly solidifies and
may be obtained in crystals melting at 69-70° C. The methyl ether of the
benzene-sulphoprotocatechuic aldehyde is not soluble in alkaline carbonates and
cold caustic soda solution. But by heating with caustic soda solution the ether is
split into the sodium salt of benzenesulphonic acid and in the sodium salt of
vanillin.
The
The methylation of p-toluenesulphoprotocatechuic aldehyde is carried out in the
same way with methyl iodide or with a salt of methylsulphuric acid.
p-toluenesulpho-vanillin crystallises from alcohol in thick needles which melt
about 115° C.
In the third operation, the splitting off of the vanillin from the sulpho derivatives
is effected by means of known saponification methods.
After
Example: 40 grammes benzenesulphovauillin are boiled with 1 litre dilute caustic
soda solution under a return condenser until the solution is perfectly clear.
acidifying the vanillin is isolated in the ordinary way.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what 1
claim is :-
1. The manufacture substantially as described of aromatic para sulpho
derivatives of protocatechuic aldehyde of the type of parabenzenesulpho-
protocatechuic aldehyde; that is to say, by the action upon protocatechuic
aldehyde of an aromatic halogenide such as benzine sulphochloride or ortho
meta or para toluine sulphochloride or a or ẞ naphtalinesulphochlorides with
the assistance of a substance combining with the acid formed as for example
an alkaline hydroxide or alkaline earth hydroxide or an alkaline carbonate or
phosphate or the like.
2. The novel aromatic sulphuryl derivatives of proto catechuic aldehyde, the
production of which is herein described.

page_text: 3. The manufacture of vanillin substantially as described by substituting an
easily removeable group for the hydrogen of the hydroxyl group which in
protocatechuic aldehyde occupies the para position in relation to the COH group,
the methylating and finally splitting off the vanillin as herein set forth.
4. The manufacture of vanillin substantially as described that is to say by
methylating the aromatic para sulpho derivatives of protocatechuic aldebyde of
the type of parabenzenesulphoprotocatechuic aldehyde and saponifying the methyl
compound.
Dated this 17th day of September 1894.
CARPMAEL & Co.,
Agents for the Applicant.