Improved Manufacture of Vanillin.
Year: 1892

page_text: Date of Application, 7th Jan., 1892
Complete Specification Left, 5th Oct., 1892-Accepted, 5th Nov., 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by the firm of C. F. BOEHRINGER & SÖHNE, of
Waldorf, near Mannheim, Manufacturers.]
Improved Manufacture of Vanillin.
I, CHARLES DENTON ABEL, Consulting Engineer and Chartered Patent Agent,
of 28 Southampton Buildings, Chancery Lane, in the County of London, do hereby
declare the nature of this invention to be as follows:-
For preparing vanillin from iso-eugenol it is necessary to protect the phenol.
group of the latter during the oxidation that has to be effected."
Heretofore this was effected by the introduction of organic acid residues, which,
after the oxidation, could be readily separated from the vanillin derivatives obtained.
With this process it was alway necessary, before the introduction of the organic
acid residue, to convert the eugenol with more or less difficulty into iso-eugenol,
and to isolate the latter in a pure condition.
My foreign correspondents have succeeded, by the introduction of certain
alcoholic residues into the eugenol, such for example as the benzyl group, in
obtaining derivatives of eugenol which allow of a smooth transformation into
derivatives of iso-eugenol, without requiring the previous isolation of the iso-
eugenol.
These derivatives offer the advantage, for the preparation of the vanillin, that
they contain a phenol group which is protected against oxidation, and that, after
the oxidation has been effected, the separation thereof can be readily effected...
In the following will be described the preparation of vanillin by means of eugenol
benzyl-ether.
The operation is divided into four parts:
I. Preparation of eugenol benzylether.
II. Transformation of the eugenol benzylether into iso-eugenol benzylether.
III. Production of vanillin-benzylether (m-methoxy-benzaldehyde-p-benzylether)
by oxidation of the iso-eugenol benzylether.
IV. Conversion of the vanillin benzylether into vanillin.
EXAMPLES.
I. 1 kilo. of eugenol is dissolved in 3 kilos. rectified spirits and to this are added
firstly 350 grammes caustic potash dissolved in a small quantity of water, and
'secondly 800 grammes of benzylchloride (or corresponding molecular quantities of
benzyl-iodide or bromide) and the whole is heated on the water bath with a reflux
cooler. The greater portion of the spirits is distilled off, and by the addition of
water eugenol benzylether, which separates as a heavy oil, is precipitated.
For separating any eugenol that may not have been converted, the oil is shaken
up with dilute alkali, and the eugenol benzylether thus purified is then distilled
in partial vacuun.
The eugenol benzylether is thus obtained as a colourless oil, which solidifies as
strong prisms having a melting point of 29° to 30° C.
II. 1 kilo. eugenol benzylether (preferably such as is obtained by the preceding
process) is dissolved in 5 kilos. rectified spirits, and 2.5 kilos. of pulverised caustic
potash is added, and the whole is then kept at boiling point for from 16 to 24 hours
in a reflux cooler.
.
The greater part of the alcohol is then distilled off, and water is added to the
residue, whereupon a brown coloured oil separates on the surface of the aqueous
5 alkaline solution and which soon solidifies to a yellowish brown crystalline mass.
CD 17

page_text: This can be purified by pressing and recrystallising from alcohol, thus obtaining
iso-eugenol benzylether in fine felted needles having the melting point of 58° to
59° C.
III. The oxidation of the iso-eugenol benzylether is effected, while observing
the precautions employed in the preparation of aldehyde by oxidation, in the
following manner. A solution of 15 kilos. of sodium chromate is poured slowly
into a mixture of 2 kilos. of sulphuric acid and 10 kilos. of water added to the iso-
eugenol benzylether.
On completion of the oxidation the product is well cooled and is disengaged by
filtration from the separated aldehyde. It is purified by recrystallization out of
rectified spirits and is thus obtained in fine needles or transparent plates of the
melting point of 63° to 64° C.
IV. 1 kilo. finely pulverised vanillin benzylether has poured over it 5 kilos.
fuming hydrochloric acid, and the mixture is allowed to stand for 24 hours in the
cold. The crystals are thereby destroyed, vanillin is produced in solution, and
benzyl chloride is separated and floats on the top, and can be used over again.
The separation is effected very smoothly. The vanillin in solution can be isolated
according to the known method, and possesses all its usual properties.
Dated this 7th day of January 1892.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Manufacture of Vanillin.
I, CHARLES DENTON ABEL, Consulting Engineer and Chartered Patent Agent,
of 28 Southampton Buildings, Chancery Lane, in the County of London, 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:-
For preparing vanillin from iso-eugenol it is necessary to protect the phenol
group of the latter during the oxidation that has to be effected. Heretofore this
was effected by the introduction of organic acid residues, which, after the oxidation,
could be readily separated from the vanillin derivatives obtained. With this
process it was always necessary, before the introduction of the organic acid residue,
to convert the eugenol with more or less difficulty into iso-eugenol, and to isolate
the latter in a pure condition.
My foreign correspondents have succeeded by the introduction of certain
alcoholic residues into the eugenol, such for example as the benzyl group, in
obtaining derivatives of eugenol which allow of a smooth transformation into
derivatives of iso-eugenol, without requiring the previous isolation of the iso-
eugenol.
These derivatives offer the advantage, for the preparation of the vanillin, that
they contain a phenol group which is protected against oxidation, and that, after
the oxidation has been effected, the separation thereof can be readily effected.
In the following will be described the preparation of vanillin by means of
eugenol benzyl-ether.
The operation is divided into four parts:
I. Preparation of eugenol benzyl ether.
II. Transformation of the eugenol benzylether into iso-eugenol benzyl-ether.
III. Production of vanillin-benzyl-ether (m-methoxy-benzaldehyde-p-benzyl-
ether) by oxidation of the iso-eugenol benzyl-ether.
IV. Conversion of the vanillin benzylether into vanillin.

page_text: secondly 800 grammes of benzylchloride (or corresponding molecular quantities of
benzyl-iodide or bromide) and the whole is heated on the water bath with a reflux
cooler. The greater portion of the spirits is distilled off, and, by the addition of
water, eugenol benzylether, which separates as a heavy oil, is precipitated.
For separating any eugenol that may not have been converted, the oil is shaken
up with dilute alkali, and the eugenol benzyl-ether thus purified is then distilled in
partial vacuum.
The eugenol benzyl-ether is thus obtained as a colourless oil, which solidifies as
strong prisms having a melting point of 29° to 30° C.
II. 1 kilo. eugenol benzylether (preferably such as is obtained by the preceding
process) is dissolved in 5 kilos. rectified spirits, and 2.5 kilos. of pulverised caustic
potash are added, and the whole is then kept at boiling point for from 16 to 24
hours in a reflux cooler.
This
The greater part of the alcohol is then distilled off, and water is added to the
residue, whereupon a brown coloured oil separates on the surface of the aqueous
alkaline solution, which soon solidifies to a yellowish brown crystalline mass.
can be purified by pressing and recrystallising from alcohol, thus obtaining iso-
eugenol benzyl-ether in fine felted needles having the melting point of 58 to
59° C.
In the above process, instead of alcohol, hydrocarbons that boil at over 80° C.
The transformation
can be employed, as for example benzene, benzol, toluol etc.
of the eugenol-benzylether into iso-eugenol-benzylether is effected in the same
manner under contact with the added caustic potash. After separation of the
solvent by distillation, the isolation takes place as described above.
III. The oxidation of the iso-eugenol-benzylether is effected while observing the
precautions employed in the preparation of aldehyde by oxidation, in the following
manner. A solution of 1.5 kilos. of sodium chromate is poured slowly into a
mixture of 2 kilos. of sulphuric acid and 10 kilos. of water added to the iso-
eugenol benzyl ether.
On completion of the oxidation the product is well cooled and is disengaged by
filtration from the separated aldehyde. It is purified by recrystallisation out of
rectified spirits and is thus obtained in fine needles or transparent plates of the
melting point of 63° to 64° C.
IV. 1 kilo. finely pulverised vanillin benzyl ether has poured over it 5 kilos. of
fuming hydrochloric acid, and the mixture is allowed to stand for 24 hours in the
cold. The crystals are thereby destroyed, vanillin is produced in solution, and
henzyl chloride is separated and floats on the top, and can be used over again.
The separation is effected very smoothly. The vanillin in solution can be isolated
according to the known method, and possesses all its usual properties.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
111
1. The herein described process for the manufacture of vanillin by preparing an
aromatic alcoholic ether of eugenol, such as eugenolbenzylether, transforming it
into an isoeugenolether, such as isoeugenolbenzylether, converting this by oxidation
into the corresponding aldehyde ether, such as vanillinbenzylether, and decom-
posing the latter into its components, namely vanillin and a derivative of the
aromatic alcohol, such as benzylchloride.
2. The vanillin produced by the above process.
ABEL & IMRAY,
Agents for the Applicant.