IMPROVEMENTS IN THE PRODUCTION OF METAOXYBENZALDEHYDE AND THE DERIVATIVES THEREOF, AND IN THE SYNTHESIS OF VANILLIN
Year: 1881

page_text: LETTERS PATENT to Joseph Anthony Dixon, of 175, West George Street,
Glasgow, in the County of Lanark, North Britain, Solicitor, for an Invention
of "IMPROVEMENTS IN THE PRODUCTION OF METAOXYBENZALDEHYDE AND
THE DERIVATIVES THEREOF, AND IN THE SYNTHESIS OF VANILLIN." A com-
munication from abroad by Dr. Karl Koenig, of Höchst-am-Main, in the
Empire of Germany, Manufacturing Chemist, and one of the Directors of
Farbwerke vorm: Meister, Lucius, & Brüning, of Höchst-am-Main, in the
German Empire.
PROVISIONAL SPECIFICATION left by the said Joseph Anthony Dixon at
the Office of the Commissioners of Patents on the 18th May 1881.
JOSEPH ANTHONY DIXON, of 175, West George Street, Glasgow, in the County
of Lanark, North Britain, Solicitor. "IMPROVEMENTS IN THE PRODUCTION OF
METAOXYBENZALDEHYDE AND THE DERIVATIVES THEREOF, AND IN THE SYNTHESIS
OF VANILLIN." [A communication from abroad by Dr. Karl Koenig, of Höchst-
am-Main, in the Empire of Germany, Manufacturing Chemist, and one of the
Directors of Farbwerke vorm; Meister, Lucius, & Brüning, of Höchst-am-Main,
in the German Empire.]

page_text: metanitrobenzaldehyde. In this case also the dichloride of tin and hydrochloric
acid are the agents best suited for the reduction of the nitro-body.
The reaction product (that is the amido compound derived from the nitrosub-
stituted metamethoxylbenzaldehyde is diluted with water, cooled down to
32° Fahr. (0°, cent.), and mixed with the calculated quantity of sodium nitrite
necessary to diazotise the amido body, and then heated.
The formation of the vanillin takes place according to the equation

page_text: PECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Joseph Anthony Dixon in the Great Seal Patent Office on the
9th September 1881.
JOSEPH ANTHONY DIXON, of 175, West George Street, Glasgow, in the County
f Lanark, North Britain, Solicitor. "IMPROVEMENTS IN THE PRODUCTION OF
IETAOXYBENZALDEHYDE AND THE DERIVATIVES THEREOF, AND IN THE SYNTHESIS
F VANILLIN." A_communication from abroad by Dr. Karl Koenig, of Höchst-
m-Main, in the Empire of Germany, Manufacturing Chemist, and one of the
Directors of Farbwerke vorm: Meister, Lucius, and Brüning, of Höchst-am-Main,
a the German Empire.

page_text: which on heating with water breaks up into meta-oxy-benzaldehyde and free
nitrogen.
I can effect the reduction of the meta-nitro-benzaldehyde to amido-benzaldehyde
(CH, COH) by the usual agents, iron, zinc, tin and tin-dichloride, with
hydrochloric or acetic acid; but the reducing agents which behave most suitably
are tin-dichloride and fuming hydrochloric acid, mixed with the meta-nitro-benzal-
dehyde in the proportions required by the formula
=
CH CHO NO + 3 Sn Cl² + 7 HCI CH, CHO NH₂ HCl + 3 Sn Cl₁ + 2 H, O.
The reduction of the nitro-benzaldehyde is accompanied by great development of
heat in the mixture.
The product of the said reaction (the hydrochloride of the amido derivative of
the nitro-benzaldehyde, viz., (C. H.
HCl), can be used direct for
CO H
NH2
the preparation of meta-oxy-benzaldehyde. Or of course the process may be
divided into two steps; first, the reduction of the amido hydrochloride above
mentioned to the diazo hydrochloride; and, second, the decomposition of the diazo
compound by heating with water into meta-oxy-benzaldehyde, nitrogen, and
hydrochloric acid, as after mentioned. It is more convenient to effect both results
by one operation.
For this purpose the amido compound above mentioned is, after having been
diluted with water and cooled down to 32° Fahr. (0° cent.), mixed with sodium nitrite
in proportion corresponding to the equation C, H, CHO NH, HCI + Na NO' + HCI
= CH CHO N = NCI + Na Cl + 2H, O, and the mixture is then heated in
order to break up the diazo hydrochloride into oxy-benzaldehyde, nitrogen, and
hydrochloric acid. The cessation of the evolution of nitrogen which accompanies
the breaking up indicates the point of time at which the breaking and conversion
of the diazo chloride (C, H, CHO N NCI) with water into meta-oxy-benzaldehyde,
=
nitrogen, and hydrochloric acid are complete.
The meta-oxy-benzaldehyde which remains in solution in the liquor can be
obtained either by evaporating the solution down to crystallisation, or by shaking
it out with ether. It is purified by recrystallisation from water, alcohol, or the
like suitable solvents, or by producing the double compound with acid sodium or
tin sulphite, and decomposing the compound by acids or by alkalies.
It is a matter of course that the removal of the metal used for the reduction of
the meta-nitro-benzaldehyde may precede instead of following the converting of the
amido-aldehyde into the said oxy-aldehyde.
The yield of the oxy-aldehyde from meta-nitro-benzaldehyde is eighty per cent.
of the quantity theoretically possible.
II. Transformation of the meta-oxy-benzaldehyde into para-nitro-meta-methoxyl-
benzaldehyde.
This transformation is effected in either of the two ways herein before mentioned
and hereinafter described.
First way. The nitroylizing of the meta-oxy-benzaldehyde is successfully effected
by means of nitric acid of various degrees of concentration, according as one works
in the cold or with heat.
Examples. One part of meta-oxy-benzaldehyde is added to the quintuple quantity
of nitric acid of 14 specific gravity; the mixture is kept cool, or one part of the
aldehyde is added to the tenfold quantity of nitric acid of 1-1 specific gravity, and
the mixture is heated gently until reaction sets in.

page_text: In all cases the liquor which is the product of the reaction is poured into water;
the nitro body which separates is collected on a filter, and purified by recrystalli-
sation; then the para-nitro-meta-oxy-benzaldehyde is transformed into a salt
which is converted into the corresponding methylic ether by means of methyl-
chloride, methyl-bromide, or methyl-iodide, with or without an addition of ethylic
alcohol, according to the equation
CH, CHO ONа NO₂ + 31CH, = C, H, CHO OCH, NO, + NaI.
Second way. By dissolving the meta-oxy-benzaldehyde in the quantity of
alcoholic solution of sodium, hydroxyde necessary for the formation of the sodium
salt of the oxy-aldehyde, and by mixing the solution with methyl-chloride, methyl-
bromide, or methyl-iodide, I obtain the meta-methoxyl benzaldehyde in nearly
theoretical quantity at an ordinary temperature after some days and at a higher
temperature after a few hours. Being purified it appears a colorless liquid, boiling
at 446° Fahr. (230° cent.).
By adding this meta-methoxyl-benzaldehyde to the quintuple quantity of nitric
acid (specific gravity 1.48), and pouring the solution into water I obtain the para-
nitro-meta-methoxyl-benzaldehyde along with an isomeric compound. These
isomers are separated from each other through crystallisation, best from
chloroform.
III. Transformation of the para-nitro-meta-methoxyl-benzaldehyde obtained by
either of the two ways herein before mentioned, or however otherwise obtained,
into vanillin.
The replacing of the nitro group of the nitro substituted ineta-methoxyl-
benzaldehyde by the hydroxyl group can be effected in the same manner as that
in which and by the same agents as those by which the same replacement of the
nitro group (NO2) by hydroxyl (OH) is effected in the case of the meta-nitro-
benzaldehyde.
In this case also the dichloride of tin and hydrochloric acid are the agents best
suited for the reduction of the nitro body.
The reaction product (that is, the amido compound derived from the nitro
substituted meta-methoxyl-benzaldehyde) is diluted with water, cooled down to
32° Fah. (0° cent.), and mixed with the calculated quantity of sodium nitrite
necessary to diazotise the amido body, and then heated.
The formation of the vanillin takes place according to the equation
C, H. CHO OCH, NH, HCl + NaNO,+HC1 =
C, H, CHO OCH, OH + Na Cl + 2N + H. O + HCl.
The vanillin thus formed is extracted by means of ether, and finally purified by
means of the compound which it can form with acid sodium sulphite.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein before in part
recited Letters Patent is,―
First. The production of meta-oxy-benzaldehyde from meta-nitro-benzaldehyde
by reduction of the same to amido benzaldehyde, and decomposition of the diazo
compound or derivative of this amido benzaldehyde with water in manner herein-
before described.
Second. The conversion of meta-oxy-benzaldehyde into para-nitro-meta-
methoxyl-benzaldehyde by either of the processes herein before described, as also,
separatim, the conversion of the said meta-oxy-benzaldehyde into para-nitro-meta-
oxy-benzaldehyde, and of the latter substance into para-nitro-meta-methoxyl-
benzaldehyde; also the conversion of meta-oxy-benzaldehyde into the meta-
methoxyl-benzaldehyde, and of the latter substance into the para-nitro-meta-
methoxyl-benzaldehyde, all in manner hereinbefore described.

page_text: Third. The artificial production of vanillin from para-nitro-meta-methoxyl-
benzaldehyde by reducing the said para-nitro-meta-methoxyl-benzaldehyde to
amido-meta-methoxyl-benzaldehyde, and decomposing with water the diazo
compound, or derivative of the said amido body, all in manner hereinbefore
described.
In witness whereof, I, the said Joseph Anthony Dixon, have hereunto set
my hand and seal, this Eighth day of September, in the year of our Lord
One thousand eight hundred and eighty one.
JOSEPH ANTHONY DIXON. (L.S.)