A PROCESS FOR THE PREPARATION OF VANILLINE OR THE AROMATIC PRINCIPLE OF VANILLE
Year: 1880

page_text: LETTERS PATENT to George de Laire, of No. 92, Rue Saint Charles, in the
City of Paris, in the Republic of France, Chemist, for an Invention of
"A PROCESS FOR THE PREPARATION OF VANILLINE OR THE AROMATIC
PRINCIPLE OF VANILLE."
PROVISIONAL SPECIFICATION left by the said George de Laire at the Office
of the Commissioners of Patents on the 16th December 1880.
GEORGE DE LAIRE, of No. 92, Rue Saint Charles, in the City of Paris, in the
Republic of France, Chemist. "A PROCESS FOR THE PREPARATION OF VANILLINE
OR THE AROMATIC PRINCIPLE OF VANILLE."
This Invention has for its object a process for the preparation of vanilline or the
aromatic principle of vanille.
"3
The material which I employ for the preparation of this substance is "eugenol
or eugenic acid. To obtain it I have recourse to an essence well known in
commerce, the essence of cloves. When the essence is of good quality and rich in
eugenol, that is to say, when it contains at least three quarters of its weight of it,
it may be employed directly without purification. When the essence is impure it
is better to separate the eugenol which it contains from the carbides and other
substances which it contains.
The essence of clove is diluted with two or three times its weight of either or of
the light benzol of commerce; the mixture is then agitated with a ley of caustic
soda containing 10 per cent. of soda, in sufficient quantity to absorb all the eugenol
which combines with the soda and passes into the aqueous liquid, whilst the other
bodies which accompany it remain in the ether or the benzol. The alkaline liquor
is separated by decantation, and then decomposed by a chemically equivalent
quantity of sulphuric acid so that the eugenol is set free. It is collected by means
of a small quantity of ether or of benzol so as to admit of its being separated more
easily from the water; then it is heated in a distilling apparatus to dry it, and to
expel the ether or the benzol which it contained.
When thus purified the eugenol is transformed into acetyl-eugenol, either by
making it react with acetic anhydride at the boiling point of the latter in a
cobobating apparatus, or by means of chloride of acetyl which reacts upon eugenol
Dmics Ad

page_text: even at the ordinary temperature. The proportions to be employed in either case
are, one equivalent of eugenol to one equivalent of anhydride or of acetic chloride.
The acetyl-eugenol thus obtained is heated for a few moments to drive off the
excess of chloride of acetyl, then washed several times with water to remove the
excess of hydrochloric acid which it contains. Thus prepared and without further
purification the acetyl-eugenol may be employed in the preparation of vanilline.
For this purpose the acetyl-eugenol is oxidised with permanganate of potash in
dilute aqueous solution. The proportions are the following:-For three parts of
acetyl eugenol eight parts by weight of permanganate of potash are required. The
solution of permanganate of potash should contain one part by weight of
permanganate to fifty parts of water. The conditions of the reaction should be
so regulated that at no time shall either free acid or alkali be in excess.
The operation may be conducted as follows:-
In a cast iron apparatus heated by steam in a coiled pipe and furnished with a
mechanical agitator, forty litres of water are heated to a temperature between
45 and 50 centigrade, then four hundred grammes of acetyl-eugenol is added; by
agitation the acetyl-eugenol is well divided as an emulsion, and then little by
little a solution of permanganate is poured into the mass (five kilogrammes of
permanganate in forty two litres of water), taking care that the liquor be strongly
agitated. The flow of the permanganate of potash is regulated by a cock in such
manner that it may take fifteen minutes or thereabout to run in. At the end of
this time the forty-two litres of the solution of permanganate having been
introduced, the agitation is continued for some minutes, the temperature being
maintained at about 60 degrees. After this the product of the reaction is
transferred to a wrought iron boiler of a capacity of about a thousand litre, and
which can be heated by a fire. The operation just described is repeated several
times (identically in the same manner) with other charges of acetyl-eugenol and of
permanganate, and when the product of ten or twelve operations has been received
in the wrought iron boiler, eight kilogrammes of caustic soda is added, and the
whole is boiled for half an hour with agitation.
At the end of this time the charge is filtered to separate the sesquioxide of
manganese formed, and the clear liquor is evaporated to one tenth. It is saturated
with sulphuric acid previously diluted with twice its volume of water.
The acidified liquor is agitated with light benzol well rectified. In this operation
the vessels employed are cylinders of wood lined with lead, furnished with screw
agitators, and fitted with three connections.
The first of these connections, situate at the upper part of the cylinder, receives a
funnel, the second at a third of the height carries a stop cock, and so does the third,
which is placed quite at the bottom of the cylinder. By the first the liquids to be
agitated are introduced, by the second the benzol is decanted, which by agitation
has been made to remove the vanilline from the acid water, by the third the spent
liquors are drawn off.
The work is so managed as to bring about a methodical separation, and to yield
in the end benzines saturated with vanilline. These benzines are then distilled
and reduced to one tenth, this tenth containing all the vanilline is agitated with
saturated bisulphite of soda in agitators analogous to those already described.
The bisulphite of soda takes up all the vanilline and leaves the impurities in the
benzine.
The combination of the bisulphite of soda with the vanilline separated by
decantation is then decomposed by sulphuric acid diluted with twice its volume of
water, and at a temperature of 70 degrees. The solution of vanilline is again
agitated with benzine, which separates the vanilline from the water. The whole of
the benzine is then driven off by distillation and vanilline is obtained, which is
purified by successive crystalizations.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George de Laire in the Great Seal Patent Office on the 15th June
1881.
"
GEORGE DE LAIRE, of No. 92, Rue Saint Charles, in the City of Paris, in the
Republic of France, Chemist. A PROCESS FOR THE PREPARATION OF VANILLINE
OR THE AROMATIC PRINCIPLE OF VANILLE."
This Invention has for its object a process for the preparation of vanilline or the
aromatic principle of vanille.
.
"
The material which I employ for the preparation of this substance is "eugenol'
or eugenic acid. To obtain it I have recourse to an essence well known in
commerce, the essence of cloves. When the essence is of good quality and rich in
eugenol, that is to say, when it contains at least three quarters of its weight of it,
it may be employed directly without purification. When the essence is impure it
is better to separate the eugenol which it contains from the carbides and other
substances which it also contains.
The essence of clove is diluted with two or three times its weight of ether or of
the light benzol of commerce; the mixture is then agitated with a ley of caustic soda
containing 10 per cent. of soda, in sufficient quantity to absorb all the eugenol,
which combines with the soda and passes into the aqueous liquid, whilst the other
bodies which accompany it remain in the ether or the benzol. The alkaline liquor
is separated by decantation, and then decomposed by a chemically equivalent
quantity of sulphuric acid so that the eugenol is set free. It is collected by means
of a quantity of ether or of benzol, so as to admit of its being separated more
easily from the water; then it is heated in a distilling apparatus to dry it and to
expel the ether or the benzol which it contained.
When thus purified the eugenol is transformed into acetyl-eugenol either by
making it react with acetic anhydride at the boiling point of the latter in a
cohobating apparatus, or by means of chloride of acetyl which reacts upon eugenol
even at the ordinary temperature. The proportions to be employed in either
case are one equivalent of eugenol to one equivalent of anhydride or of acetic
chloride.
The acetyl-eugenol thus obtained is heated for a few moments to drive off the
excess of chloride of acetyl, then washed several times with water to remove the
excess of bydrochloric acid which it contains. Thus prepared and without further
purification the acetyl eugenol may be employed in the preparation of vanilline.
For this purpose the acetyl-eugenol is oxidised with permanganate of potash in
dilute aqueous solution. The proportions are the following:-For three parts of
acetyl-eugenol eight parts by weight of permanganate of potash are required. The
solution of permanganate of potash should contain one part by weight of per-
manganate to fifty parts of water. The conditions of the reaction should be so
regulated that at no time shall either free acid or alkali be in excess.
The operation may be conducted as follows:-
In a cast iron apparatus, heated by steam in a coiled pipe and furnished with
a mechanical agitator, forty litres of water are heated to a temperature between
45 and 50 centigrade. Then four hundred grammes of acetyl-eugenol is added;
by agitation the acetyl-eugenol is well divided as an emulsion, and then little by
little a solution of permanganate is poured into the mass (five kilogrammes of
permanganate in forty two litres of water), taking care that the liquor be strongly
agitated. The flow of the permanganate of potash regulated by a cock in such
manner that it may take fifteen minutes or thereabout to run in. At the end of
this time the forty two litres of the solution of permanganate having been

page_text: introduced, the agitation is continued for some minutes, the temperature being
maintained at about 60 degrees. After this the product of the reaction is
transferred to a wrought iron boiler of a capacity of about a thousand litres, and
which can be heated by a fire. The operation just described is repeated several
times (identically in the same manner) with other charges of acetyl-eugenol and
of permanganate, and when the product of ten or twelve operations has been
received in the wrought iron boiler, eight kilogrammes of caustic soda is added, and
the whole is boiled for half an hour with agitation.
At the end of this time the charge is filtered to separate the sesquioxide of
manganese formed, and the clear liquor is evaporated to one tenth. It is satuarated
with sulphuric acid previously diluted with twice its volume of water.
The acidified liquor is agitated with light benzol well rectified. In this operation
the vessels employed are cylinders of wood lined with lead, furnished with screw
agitators, and fitted with three connections.
The first of these connections, situate at the upper part of the cylinder, receives
a funnel, the second at a third of the height carries a stop cock, and so does the
third, which is placed quite at the bottom of the cylinder. By the first the liquids
to be agitated are introduced, by the second the benzol is decanted, which by
agitation has been made to remove the vanilline from the acid water, by the third
the spent liquors are drawn off.
The work is so managed as to bring about a methodical separation, and to yield
in the end benzines saturated with vanilline. These benzines are then distilled
and reduced to one tenth; this tenth containing all the vanilline is agitated with
saturated bisulphite of soda in agitators analogous to those already described.
The bisulphite of soda takes up all the vanilline and leaves the impurities in
the benzine.
The combination of the bisulphite of soda with the vanilline separated by
decantation is then decomposed by sulphuric acid diluted with twice its volume
of water, and at a temperature of 70 degrees. The solution of vanilline is again
agitated with benzine, which separates the vanilline from the water. The whole
of the benzine is then driven off by distillation, and vanilline is obtained which is
purified by successive crystallizations.
Having thus described the nature of my Invention, and the manner of performing
the same, I would have it understood that I claim, the manufacturing process for
producing vanilline from eugenol, substantially as herein described.
In witness whereof, I, the said George de Laire, have hereunto set my hand
and seal, this Fourteenth day of June, in the year of our Lord One
thousand eight hundred and eighty one.
G. DE LAIRE. (L.S.)