TECHNICAL FIELD
[0001]
The present invention relates to a process for preparing an aromatic aldehyde
compound which comprises the reaction of an aromatic methyl alcohol compound and a
peroxide under a pH value of a reaction solution being pH 0.01 or higher and less than
10, in the presence of at least one metal compound selected from a molybdenum
compound and a tungsten compound, and at least one salt selected from at least one salt
selected from a quaternary ammonium salt and an organic phosphonium salt.
The aromatic aldehyde compound obtained by the preparation process of the
present invention is a compound useful for various kinds of chemical products, for
example, such as medical and agricultural chemicals and organic materials, and their
starting intermediates.
BACKGROUND ART
[0002J
Heretofore, as a method for preparing an aromatic aldehyde compound from an
aromatic methyl alcohol compound, there have been well known, for example, a method
of oxidizing a primary alcohol by using a metal oxide such as manganese oxide and
pyridinium chlorochromate (PCC), etc. (for example, see Non-Patent Literature 1 and
Non-Patent Literature 2.) or a reaction of Swern oxidation, etc. (for example, see Non-
Patent Literature 3.). However, these reactions involve problems for carrying out the
methods industrially because the reaction is carried out by using a metal reagent having
high toxicity, or wastes occurs such as dimethylsulfide which accompanies bad smell
after termination of the reaction so that environmental load is large.
[00031
On the other hand, a method of utilizing hydrogen peroxide has attracted
attention in recent years because handling of hydrogen peroxide is easy, it can be
decomposed to harmless water after the reaction, and further it is inexpensive (for
example, see Patent Literature 1.).
[00041
[Patent Literature 1] JP HI 1-158107A
2
[Non-Patent Literature 1] Organic Letters, Vol. 5,4725 (2003)
[Non-Patent Literature 2] J. Org. Chem., Vol. 69,1453 (2004)
[Non-Patent Literature 3] Tetrahedron, Vol. 34,1651 (1978)
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0005]
For example, in Patent Literature 1, as a method for preparing a carbonyl
compound such as an aldehyde, etc., by reacting a primary alcohol and hydrogen
peroxide, a method of using a sodium tungstate/quaternary ammonium hydrogen sulfate
catalyst has been reported. When the present inventors has actually synthesized
piperonal which is an aromatic aldehyde compound by using this method, but the yield
was 24.9%, so that this method is not satisfied in view of an industrial preparation
method very well.
An object of the present invention is to provide a process for preparing an
aromatic aldehyde compound from an aromatic methyl alcohol compound with good
yield by an industrially advantageous process which can provide the product with high
conversion and high reaction selectivity.
MEANS TO SOLVE THE PROBLEMS
[00061
The problem of the present invention can be solved by a process for preparing
an aromatic aldehyde compound represented by the formula (2):
[00071
[Formula 2]
> I (2)
(R)irv>
[0008]
(wherein R represents a halogen atom, a hydrocarbon group having 1 to 12 carbon
atoms, an alkyloxy group having 1 to 12 carbon atoms, a phenyloxy group, a naphthyloxy
group, a benzyloxy group or a phenethyloxy group, each group of which may have
a substituent(s); n is an integer of 0 to 5; and when n is 2 or more, Rs may form a ring
by combining with each other.)
which comprises reacting an aromatic methyl alcohol compound represented by the
formula (1):
[0009]
[Formula 1]
Jr T <1>
(R)rrvy
[0010J
(wherein R and n have the same meanings as defined above.)
and a peroxide under a pH value of a reaction solution being a pH of 0.01 or higher and
less than 10, in the presence of at least one metallic compound selected from a
molybdenum compound and a tungsten compound and at least one salt selected from a
quaternary ammonium salt and an organic phosphonium salt.
EFFECTS OF THE INVENTION
[00111
According to the preparation process of the present invention, from various
aromatic methyl alcohol compounds, corresponding aromatic aldehyde compounds can
be obtained with good yield as compared with the conventional methods.
[00121
Also, the preparation process of the present invention is a preparation process
containing an operation method which is simple and easy, and which is less load to
environment since an amount of harmful waste is little.
[0013]
Further, the preparation process of the present invention gives an objective
aromatic aldehyde compound with good yield, for example, when an aqueous hydrogen
peroxide is used as a peroxide, and even when an amount of the aqueous hydrogen
peroxide to be used is an equivalent molar amount to that of an aromatic methyl alcohol
compound, so that this is a preparation process which can also relief against the operation
risk accompanied by using an excessive amount of a peroxide in the conventional
method.
BEST MODE TO CARRY OUT THE INVENTION
[00141
The aromatic aldehyde compound represented by the formula (2) of the present
invention can be obtained by reacting an aromatic methyl alcohol compound and a
peroxide under a pH value of a reaction solution being a pH of 0.01 or higher and less
than 10 in the presence of at least one metallic compound selected from a molybdenum
4
compound and a tungsten compound and at least one salt selected from a quaternary
ammonium salt and an organic phosphonium salt.
[0015]
In the reaction of the present invention, the aromatic methyl alcohol compound
as the starting material is represented by the above-mentioned formula (1). In the
formula, R represents a halogen atom, a hydrocarbon group having 1 to 12 carbon
atoms, an alkyloxy group having 1 to 12 carbon atoms, a phenyloxy group, a naphthyloxy
group, a benzyloxy group or a phenethyloxy group. Additionally, these groups
may have a substhuent(s). Also, n is an integer of 0 to 5. Further, when n is 2 or
more, Rs may form a ring by combining with each other.
[0016]
In the formula (1), in R, the halogen atom means a fluorine atom, chlorine
atom, bromine atom or iodine atom.
[0017]
In the formula (1), in R, the above-mentioned hydrocarbon group having 1 to
12 carbon atoms may be mentioned a linear, branched or cyclic aliphatic group (for
example, a methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl
group, n-butyl group, isobutyl group, t-butyl group, cyclobutyl group, n-pentyl group, ipentyl
group, s-pentyl group, amyl group, cyclopentyl group, n-hexyl group and
cyclohexyl group, etc.), an aromatic group (for example, a phenyl group, naphthyl
group and benzyl group, etc.), and an aliphatic group to which an aromatic group is
bonded (an aralkyl group: for example, a benzyl group, phenethyl group, etc.). These
groups contain various kinds of isomers.
[0018]
In the formula (1), in R, the above-mentioned alkyloxy group having 1 to 12
carbon atoms is a group in which a linear, branched or cyclic aliphatic group is bonded
to an oxygen atom (for example, a methoxy group, ethoxy group, propyloxy group,
isopropyloxy group, cyclopropyloxy group, n-butyloxy group, isobutyloxy group, tbutyloxy
group, cyclobutyloxy group, n-pentyloxy group, i-pentyloxy group, s-pentyloxy
group, amyloxy group, cyclopentyloxy group, n-hexyloxy group and cyclohexyloxy
group, etc.). These groups contain various kinds of isomers.
[0019]
Also, the above-mentioned hydrocarbon group, alkyloxy group, phenyloxy
group, naphthyloxy group, benzyloxy group or phenethyloxy group may have a substituent(
s). As the substituent(s), there may be mentioned a halogen atom, an alkyl group
having 1 to 6 carbon atoms (including various kinds of isomers), and an alkyloxy group
5
having 1 to 6 carbon atoms (including various kinds of isomers). One or more kinds of
these substituents may be bonded to the above-mentioned hydrocarbon group.
[0020]
Further, when n is 2 or more, Rs may be combined with each other to form a
ring with the adjacent carbon atoms of the benzene ring. Such a ring may be
mentioned, for example, a chromane ring, alkylenedioxy ring, naphthalene ring, indane
ring, tetrahydronaphthalene ring, etc., which are combined with the benzene ring of the
formula (1).
[0021]
The aromatic aldehyde compound obtained by the preparation process of the
present invention is represented by the above-mentioned formula (2). In the formula
(2), R and n have the same meanings as in the above-mentioned formula (1).
[0022]
The aromatic aldehyde compound represented by the formula (2) may be
preferably mentioned benzaldehyde, naphthylaldehyde, tetrahydronaphthylaldehyde,
chromanecarbaldehyde, and compounds shown by the following formulae (3) to (7).
[0023]
[Formula 3]
jcr- :xr~»~cc-
[0024]
(wherein R'and R2 each represent a hydrogen atom, a hydrocarbon group having 1 to 12
carbon atoms, an alkyloxy group having 1 to 12 carbon atoms, a phenyloxy group, a
naphthyloxy group, a benzyloxy group or a phenethyloxy group, each group of which
may have a substituent(s); and m is 1 or 2)
[0025]
Here, in the formula (3) to formula (7), R*and R2 each represent a hydrogen
atom, a hydrocarbon group having 1 to 12 carbon atoms, an alkyloxy group having 1 to
12 carbon atoms, a phenyloxy group or a naphthyloxy group, a benzyloxy group or a
phenethyloxy group. Additionally, these groups may have a substituent(s). m is 1 or
2.
6
[0026]
The hydrocarbon group having 1 to 12 carbon atoms, the alkyloxy group
having 1 to 12 carbon atoms, the phenyloxy group, the naphthyloxy group, the benzyloxy
group or the phenethyloxy group, and the substituent(s) which may be bonded to
the above groups in R*and R2 have the same meanings as defined in the abovementioned
formula (1).
[0027]
The aromatic aldehyde compound represented by the formula (2) may be
preferably mentioned a compound wherein R is an aliphatic group having 1 to 4 carbon
atoms or a benzyl group, the compounds of the formulae (3) to (6) and the compound of
the formula (7) wherein m is 1 (piperonal).
[0028]
The peroxide to be used in the reaction of the present invention, there may be
mentioned, for example, an inorganic peroxide such as aqueous hydrogen peroxide, a
persulfate compound (for example, persulfuric acid, sodium hydrogen persulfate,
potassium hydrogen persulfate, etc.), etc., or an organic peroxide such as t-butyl hydroperoxide,
meta-chloroperbenzoic acid, performic acid, peracetic acid and perpropionic
acid, etc., and hydrogen peroxide is preferably used. The above-mentioned peroxide
may be used alone or may be used in admixture of two or more kinds. The peroxide
may be used as such, or may be used by dissolving or suspending in water, or an
organic solvent such as an alcohol, etc., or a mixed solvent thereof.
[0029]
An amount of the peroxide to be used is preferably 0.1 to 5 mol, more
preferably 0.2 to 3 mol, further preferably 0.8 to 2.1 mol, particularly preferably 0.9 to
1.5 mol, and particularly more preferably 0.95 to 1.3 mol based on 1 mol of the
aromatic methyl alcohol compound.
[0030]
It has been known that, for example, an aqueous hydrogen peroxide is used as a
peroxide in an excessive amount, the excessive portion are decomposed during the
reaction or after completion of the reaction to generate an oxygen. When the amount
of the generating oxygen becomes larger and larger, it causes a serious problem in terms
of safety operation because it forms a flammable or explosive mixed gas with a vapor
comprising a solvent, an aromatic methyl alcohol compound and an aromatic aldehyde
compound.
Thus, according to the process of the present invention, it is desired to use
hydrogen peroxide as little as possible with the progress of the reaction within the range
7
of not exceeding 5 mol based on 1 mol of the aromatic methyl alcohol compound.
On the other hand, in case of an amount of the hydrogen peroxide to be used is
less than 0.8 mol based on 1 mol of the aromatic methyl alcohol compound, decomposition
or side reaction of the aromatic methyl alcohol compound occurs when the
remaining unreacted aromatic methyl alcohol compound is separated or recovered by
distillation, etc., after completion of the reactioa In particular, in the case of using an
aromatic methyl alcohol compound having an electron donative substituent such as an
alkoxy group or methylenedioxy group at the aromatic ring, it sometimes becomes a
serious problem. Accordingly, an amount of the hydrogen peroxide to be used is
desirably 0.8 mol or more based on 1 mol of the aromatic methyl alcohol compound.
[0031]
When an aqueous hydrogen peroxide is used as the above-mentioned peroxide,
the concentration thereof is not particularly limited, and it is preferably 10 to 90%
aqueous solution, more preferably 30 to 80% aqueous solution, and further preferably
50 to 70% aqueous solution.
Also, the process of the present invention may be carried out, for example, by
adding an aqueous hydrogen peroxide solution to a reaction system finally which is
different from an operation method disclosed in Patent Literature 1. That is, the
present invention is a preparation process which may be carried out by adding a
peroxide dropwise continuously or stepwisely, for the purpose of, for example,
confirming the condition of consumed peroxide during the reaction or controlling the
progress of the reaction.
Accordingly, in the process of the present invention, by carrying out the
operation method as mentioned above, it may be used, for example, 30% aqueous
hydrogen peroxide solution which is a commercially available product as such.
Moreover, even when an aqueous solution with a higher concentration such as a 60%
aqueous hydrogen peroxide solution, etc., is used, the aromatic aldehyde compound can
be prepared by a process which is safer and an amount of waste after the reaction is
reduced.
[0032]
The reaction of the present invention is carried out in the presence of at least
one metallic compound selected from a molybdenum compound and a tungsten
compound.
[0033]
The molybdenum compound to be used in the reaction of the present invention
may be mentioned, for example, molybdenum hydroxide, an alkali molybdate
8
compound (for example, lithium molybdate, potassium molybdate, sodium molybdate,
etc.), an alkaline earth metal molybdate compound (for example, calcium molybdate,
barium molybdate, etc.), a molybdenum compound comprising molybdenum and an
element of Group Illb, IVb, Vb or VIb (for example, cerium molybdate, iron
molybdate, etc.), ammonium molybdate, molybdenum dioxide, molybdenum trioxide,
molybdenum trisulfide, molybdenum hexachloride, molybdenum silicate, molybdenum
boride, molybdenum nitride, molybdenum carbide, phosphomolybdic acid, an alkali
phosphomolybdate compound (for example, sodium phosphomolybdate, etc.),
ammonium phosphomolybdate, molybdenum hexacarbonyl silver molybdate, cobalt
molybdate, etc. These molybdenum compounds may be a hydrate, for example,
sodium molybdate dihydrate, potassium molybdate dihydrate, etc.
The molybdenum compound is preferably a molybdenum compound which can
easily generate a molybdate anion among the above-mentioned compounds, and
concrete examples thereof may be more preferably mentioned an alkali molybdate
compound, molybdenum dioxide, molybdenum trioxide, phosphomolybdic acid, an
alkali phosphomolybdate compound and molybdenum hexacarbonyl, particularly
preferably sodium molybdate dihydrate, potassium molybdate dihydrate, molybdenum
dioxide, molybdenum trioxide and molybdenum hexacarbonyl, and particularly more
preferably sodium molybdate dihydrate, potassium molybdate dihydrate, molybdenum
dioxide and molybdenum hexacarbonyl.
[0034]
The tungsten compound to be used in the reaction of the present invention may
be mentioned, for example, tungstic acid, an alkali tungstate compound (for example,
sodium tungstate, potassium tungstate, etc.), a tungsten compound comprising tungsten
and an element of Group Illb, IVb, Vb or VIb (for example, cobalt(II) tetraoxotungstate
(IV), ferric oxytungstate, etc.), ammonium tungstate, tungsten dioxide, tungsten
trioxide, tungsten trisulfide, tungsten hexachloride, tungsten silicate, tungsten boride,
tungsten nitride, tungsten carbide, phosphotungstic acid, an alkali phosphotungstate
compound (for example, sodium phosphotungstate, etc.), ammonium phosphotungstate,
tungsten hexacarbonyl, silver tungstate, cobalt tungstate, etc. These tungsten
compounds may be a hydrate, for example, sodium tungstate dihydrate, potassium
tungstate dihydrate, etc.
The tungsten compound is preferably a tungsten compound which can easily
generate a tungstate anion among the above-mentioned compounds, and concrete
examples thereof may be more preferably mentioned an alkali tungstate compound,
tungsten trioxide, phosphotungstic acid, an alkali phosphotungstate compound and
9
tungsten hexacarbonyl, and particularly preferably sodium tungstate dihydrate and
potassium tungstate dihydrate.
[0035]
At least one metallic compound selected from the above-mentioned
molybdenum compound and tungsten compound each may be used singly, or may be
used in admixture of two or more kinds selected from the respective compounds.
Also, to carry out the reaction of the present invention more effectively, it may be
carried out, for example, by using a metal catalyst of a transition metal, etc., such as
scandium, cerium, titanium, zirconium, iron, aluminum, ruthenium, nickel, palladium,
platinum, copper, silver, gold, zinc, bismuth, antimony, etc., in combination.
Moreover, the molybdenum compound and the tungsten compound may be used as
such, or may be used by dissolving or suspending in water, an organic solvent such as
an alcohol, etc., or a mixed solvent thereof.
[0036]
An amount of at least one metallic compound to be used selected from the
molybdenum compound and the tungsten compound of the present invention is
preferably 0.0001 to 0.10 mol, more preferably 0.0005 to 0.08 mol, and particularly
preferably 0.001 to 0.05 mol based on 1 mol of the aromatic methyl alcohol compound.
[0037]
The reaction of the present invention is carried out in the presence of at least
one salt selected from a quaternary ammonium salt and an organic phosphonium salt.
[0038]
The quaternary ammonium salt to be used in the present invention may be
mentioned a quaternary ammonium hydrogen sulfate and/or a quaternary ammonium
halide.
The quaternary ammonium hydrogen sulfate may be mentioned, for example,
tetrapropyl ammonium hydrogen sulfate, tetrabutyl ammonium hydrogen sulfate, tetran-
hexyl ammonium hydrogen sulfate, benzyltrimethyl ammonium hydrogen sulfate,
benzyltriethyl ammonium hydrogen sulfate, lauryltrimethyl ammonium hydrogen
sulfate, stearyltrimethyl ammonium hydrogen sulfate, dilauryldimethyl ammonium
hydrogen sulfate, methyltrioctyl ammonium hydrogen sulfate, ethyltrioctyl ammonium
hydrogen sulfate, N-laurylpyridinium hydrogen sulfate, N-cetylpyridinium hydrogen
sulfate, N-laurylpicolinium hydrogen sulfate, N-cetylpicolinium hydrogen sulfate, Nlaurylquinolium
hydrogen sulfate and N-cetylquinolium hydrogen sulfate, etc.
The quaternary ammonium halide is preferably a quaternary ammonium halide
of chloride or bromide, and may be mentioned, for example, tetramethyl ammonium
10
chloride, tetramethyl ammonium bromide, tetraethyl ammonium chloride, tetraethyl
ammonium bromide, tetrapropyl ammonium chloride, tetrapropyl ammonium bromide,
tetrabutyl ammonium chloride, tetrabutyl ammonium bromide, benzyltriethyl ammonium
chloride, benzyltriethyl ammonium bromide, lauryltrimethyl ammonium chloride,
stearyltrimethyl ammonium chloride, dilauryldimethyl ammonium chloride, methyltrioctyl
ammonium chloride, ethyltrioctyl ammonium chloride, N-laurylpyridinium
chloride, N-cetylpyridinium chloride, N-laurylpicolinium chloride, N-cetylpicolinium
chloride, N-laurylquinolium chloride and N-cetylquinolium chloride, etc.
These quaternary ammonium salts may be a hydrate.
The quaternary ammonium salt may be more preferably mentioned tetrabutyl
ammonium hydrogen sulfate, tetra-n-hexyl ammonium hydrogen sulfate, tetrabutyl
ammonium chloride and tetrabutyl ammonium bromide.
[0039]
The above-mentioned quaternary ammonium salts may be used singly, or in
admixture of two or more kinds. Also, the quaternary ammonium salt may be used as
such, or may be used by dissolving in water, an organic solvent such as an alcohol, etc.,
or a mixed solution thereof.
[0040]
An amount of the quaternary ammonium salt to be used in the present
invention is preferably 0.0001 to 0.10 mol, more preferably 0.0005 to 0.08 mol, and
particularly preferably 0.001 to 0.05 mol based on 1 mol of the aromatic methyl alcohol
compound.
[0041]
The organic phosphonium salt to be used in the present invention may be
mentioned an organic phosphonium salt having an aromatic substituent(s) and/or alkyl
substituent(s).
The organic phosphonium salt may be mentioned, for example, tetrabutylphosphonium
chloride, tetrabutylphosphonium bromide, tetraphenylphosphonium
chloride, tetraphenylphosphonium bromide, tetraphenylphosphonium iodide, tetramethylphosphonium
chloride, tetramethylphosphonium bromide, tetramethylphosphonium
iodide, etc., and preferably tetrabutylphosphonium chloride, tetrabutylphosphonium
bromide, tetraphenylphosphonium chloride and tetraphenylphosphonium bromide.
[0042]
The above-mentioned organic phosphonium salt may be used alone or in
admixture of two or more kinds. Also, the organic phosphonium salt may be used as
such, or may be used by dissolving or suspending in water, an organic solvent such as
11
an alcohol, etc., or a mixed solvent thereof.
[0043]
An amount of the organic phosphonium salt to be used in the present invention
is preferably 0.0001 to 0.10 mol, more preferably 0.0005 to 0.08 mol, and particularly
preferably 0.001 to 0.05 mol based on 1 mol of the aromatic methyl alcohol compound.
[0044]
The reaction of the present invention may be carried out by adding at least one
buffer selected from a phosphoric acid compound, a boric acid compound and a
carbonic acid compound to the reaction mixture for the purpose of, for example, making
pH adjustment simple and easy, stabilizing a peroxide, etc.
[0045]
The phosphoric acid compound to be used in the reaction of the present
invention may be mentioned, for example, phosphoric acid (orthophosphoric acid,
pyrophosphoric acid, metaphosphoric acid), an alkali metal salt of phosphoric acid (for
example, sodium phosphate, potassium phosphate, etc.), an alkaline earth metal salt of
phosphoric acid (for example, calcium phosphate, etc.), an alkali metal salt of hydrogen
phosphate compound (for example, sodium monohydrogen phosphate, sodium
dihydrogen phosphate, potassium monohydrogen phosphate, potassium dihydrogen
phosphate, etc.), and ammonium phosphate.
[0046]
The boric acid compound to be used in the reaction of the present invention
may be mentioned, for example, boric acid (orthoboric acid, metabolic acid, tetraboric
acid), an alkali metal salt of boric acid, an alkaline earth metal salt of boric acid (for
example, potassium borate calcium tetraborate, etc.), and ammonium borate.
[0047]
The carbonic acid compound to be used in the reaction of the present invention
may be mentioned, for example, carbonic acid, an alkali metal salt of carbonic acid (for
example, sodium carbonate, potassium carbonate, etc.), an alkaline earth metal salt of
carbonic acid (for example, calcium carbonate, etc.), an alkali metal salt of a hydrogen
carbonate compound (for example, sodium hydrogen carbonate, potassium hydrogen
carbonate, etc.).
The above-mentioned phosphoric acid compound, boric acid compound and
carbonic acid compound may be used alone or in admixture of two or more kinds.
These compounds may be used as such, or may be used by dissolving or suspending in
water, an organic solvent such as an alcohol, etc., or a mixed solvent thereof.
[0048]
12
Among the above-mentioned compounds, a phosphoric acid compound is
preferably used in the view point of stability of the peroxide during the reaction. An
amount of at least one buffer selected from a phosphoric acid compound, a boric acid
compound and a carbonic acid compound to be used is preferably 0.0001 to 0.005 mol,
more preferably 0.0003 to 0.05 mol, and particularly preferably 0.0005 to 0.03 mol
based on 1 mol of the aromatic methyl alcohol compound.
[0049]
The reaction of the present invention can be carried out in the absence of a
solvent or in the presence of a solvent.
The solvent to be used is not particularly limited so long as it does not inhibit
the reaction, and there may be mentioned, for example, water, formic acid, aliphatic
carboxylic acids (for example, acetic acid, propionic acid, trifluoroacetic acid, etc.),
organic sulfonic acids (for example, methanesulfonic acid, trifluoromethanesulfonic
acid, etc.), alcohols (for example, methanol, ethanol, isopropyl alcohol, t-butyl alcohol,
ethylene glycol, Methylene glycol, etc.), ketones (for example, acetone, butanone,
cyclohexanone), aliphatic hydrocarbons (for example, n-pentane, n-hexane, n-heptane,
cyclohexane, etc.), amides (for example, N,N-dimethylformamide, N,N-dimethylacetamide,
N-methylpyrrolidone, etc.), ureas (N,N'-dimethylimidazolidinone, etc.), ethers
(for example, diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, 1,2-methylenedioxybenzene,
etc.), aromatic hydrocarbons (for example, benzene, toluene, xylene,
etc.), halogenated aromatic hydrocarbons (for example, chlorobenzene, 1,2-dichlorobenzene,
1,3-dichlorobenzene, 1,4-dichlorobenzene, etc.), nitrated aromatic hydrocarbons
(for example, nitrobenzene, etc.), halogenated hydrocarbons (for example,
methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, etc.),
carboxylates (for example, ethyl acetate, propyl acetate, butyl acetate, etc.), nitriles (for
example, acetonitrile, propionitrile, benzonitrile, etc.), sulfoxides (for example,
dimethylsulfoxide, etc.), sulfones (for example, sulfolane, etc.) and the like. These
solvents may be used alone or in admixture of two or more kinds.
[0050]
When the above-mentioned solvent(s) is/are used, an amount to be used is
optionally controlled depending on the uniformity of the reaction solution or stirrability
thereof, and it is, for example, preferably 0.1 to 1000 g, more preferably 0.3 to 500 g,
particularly preferably 0.5 to 200 g, and particularly more preferably 0.5 to 100 g based
on 1 g of the aromatic methyl alcohol compound.
[0051]
A range of the pH value of the reaction solution of the present invention is a
13
pH of 0.01 or higher and less than 10. When a molybdenum compound is used as the
metallic compound, it is preferably a pH of 0.01 to 10, more preferably a pH of 0.01 or
higher and less than 9, particularly preferably a pH of 0.1 or higher and less than 9,
particularly more preferably a pH of 0.5 or higher and less than 9, particularly more
preferably a pH of 0.8 or higher and less than 9, and particularly preferably a pH of 1 or
higher and less than 9. On the other hand, when a tungsten compound is used as the
metallic compound, it is preferably a pH of 3 or higher and less than 8, more preferably
a pH of 4 to 7.5, and particularly preferably a pH of 5 to 7.
[0052J
The reaction of the present invention is considered to be carried out with good
yield, for example, even when a pH value of the reaction solution is pH of less than
0.01. However, an object of the present invention is to provide an industrially
preferable preparation process, and it is not actually usual to use a device which can
accurately measure a pH of less than 0.01 for a commercial purpose. Accordingly, a
pH of 0.01 or more which is detection limit of commercially available measurement
device is determined as a lower limit of the pH value of the reaction solution to be used
in the reaction of the present invention. On the other hand, in case of the pH value of
the reaction solution is a pH of 10 or more, the peroxide which is a starting material is
easily decomposed so that it is not preferred. Accordingly, in the present invention, by
carrying out the reaction within the above-mentioned pH range of the reaction solution,
an aromatic aldehyde compound can be prepared with higher conversion, higher
reaction selectivity and good yield as compared with the conventional preparation
methods.
In particular, when an aromatic methyl alcohol compound in which an electron
donative group(s) such as an alkoxy group and methylenedioxy group, etc., is/are
substituted on the aromatic ring is to be used, these has a tendency of higher reactivity.
Thus, if the reaction is not carried out within the above-mentioned pH range, it can be
considered that there is higher possibility of generating by-product(s). That is, in the
reaction of the present invention, it is particularly important to adjust the pH of the
reaction solution.
[0053]
In the reaction of the present invention, the compound to be used for pH
adjustment of the reaction solution, etc. (hereinafter sometimes referred to as apH
adjusting agent.) is not particularly limited so long as it does not inhibit the reaction.
As the pH adjusting agent, there may be mentioned, for example, a hydroxide
of an alkali metal and a hydroxide of an alkaline earth metal (for example, lithium
14
hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium
hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, etc.), a
carbonate of an alkali metal and a carbonate of an alkaline earth metal (for example,
lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium
carbonate, magnesium carbonate, calcium carbonate, strontium carbonate), an alkoxide
of an alkali metal and an alkoxide of an alkaline earth metal (for example, lithium
methoxide, sodium methoxide, potassium methoxide, rubidium methoxide, cesium
methoxide, calcium methoxide, magnesium methoxide), a carboxylate of an alkali metal
and a carboxylate of an alkaline earth metal (for example, sodium acetate, potassium
acetate, sodium oxalate, potassium oxalate), a phosphate of an alkali metal and a
phosphate of an alkaline earth metal (for example, sodium phosphate, etc.), phosphoric
acid, hydrochloric acid, sulfuric acid, boric acid, etc. As the pH adjusting agent, the
above-mentioned buffer may be used.
The pH adjusting agent is preferably a hydroxide of an alkali metal, a
hydroxide of an alkaline earth metal, a carbonate of an alkali metal, a carbonate of an
alkaline earth metal, a phosphate of an alkali metal, a phosphate of an alkaline earth
metal, phosphoric acid and boric acid. The above-mentioned pH adjusting agent may
be used singly, or in admixture of two or more kinds. The above-mentioned
compound may be used as such, or may be used by dissolving or suspending in water,
an organic solvent such as an alcohol, etc., or a mixed solvent thereof.
[0054]
A reaction temperature of the present invention is not particularly limited, and
preferably carried out at 20°C to 150°C, more preferably 40°C to 140°C, particularly
preferably 60°C to 130°C to avoid complexity in operation such as cooling, raising
temperature, etc.
[0055]
A reaction pressure of the reaction according to the present invention is not
particularly limited. Also, the reaction conditions are not particularly limited, but in
the reaction of the present invention, there are some cases where the above-mentioned
safety becomes a problem due to generation of oxygen accompanied by the decomposition
of hydrogen peroxide to be used, so that it is preferably carried out under an inert
gas (for example, nitrogen, argon, helium) stream, or under an inert gas atmosphere.
[0056]
In the reaction of the present invention, an order of addition of the starting
materials is not particularly limited, and in the operation method of the present
invention, by carrying out the operation method, for example, in which a peroxide is
15
finally added to the reaction system dropwise continuously or stepwisely, etc., a
condition of consumed peroxide can be confirmed during the reaction, whereby the
reaction can be carried out while controlling the reaction conditions. By carrying out
the operation method, the product can be prepared safety even when a peroxide with a
higher concentration, for example, 60% aqueous hydrogen peroxide solution, etc., is
used. Accordingly, in the preparation process of the present invention, it is preferred
to employ a method in which a peroxide is finally added to the reaction media as an
order of addition of the starting materials.
EXAMPLES
[0057]
Next, the present invention is specifically explained by referring to Examples,
but the scope of the present invention is not limited by these.
[0058]
Example 1 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; 4.0 to 5.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 213 g of toluene, 127.7
g (839 mmol) of piperonyl alcohol, 3.07 g (12.7 mmol) of sodium molybdatedihydrate
(Na2Mo04-2H20), 4.32 g (12.7 mmol) of tetrabutyl ammonium hydrogen sulfate and
18.0 g of water. Then, to the mixture were added 0.50 g (3.20 mmol) of sodium
dihydrogenphosphatedihydrateand2.05 g (5.72mmol) ofdisodiumhydrogen
phosphate* 1 dihydrate (a pH value at this time was 4.87.). An inner temperature of the
reaction mixture was maintained from 84 to 85°C, and 52.0 g (0.92 mol) of 60%
aqueous hydrogen peroxide was added dropwise to the mixture with 230 mmol/hr,
while maintaining the pH of the reaction mixture to 4.0 to 5.0. After completion of the
dropwise addition, the mixture was reacted for further one hour.
After completion of the reaction, the resulting reaction mixture was cooled to
room temperature, and when the organic layer solution was quantitatively analyzed by
HPLC (measured wavelength: 256 nm: absolute calibration method), then, the reaction
yield of piperonal was 100.0% (Conversion of piperonyl alcohol: 99.0%).
Next, the solvent was distilled off from the organic layer solution, and the
resulting white solid (piperonal) was analyzed, then, the physical properties thereof
were as follows.
MS spectrum (CI-MS); 151 [M]+
^-NMR spectrum (300 mHz, CDC13) 8 (ppm); 6.07 (2H, s), 6.93 (1H, d, J=7.8Hz),
16
7.32 (1H, d, J=1.5Hz), 7.40,7.42 (1H, dd, J=1.5Hz), 9.81 (1H, s)
[0059]
Example 2 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; 0.01 to 1.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 213 g of toluene, 125.5
g (825 mmol) of piperonyl alcohol, 3.05 g (12.6 mmol) of sodium molybdatedihydrate
(Na2Mo04-2H20), 4.18 g (12.3 mmol) of tetrabutyl ammonium hydrogen sulfate and
18.0 g of water. Then, to the mixture were added 0.30 g (1.92 mmol) sodium
dihydrogenphosphatedihydrateand 1.80 g(5.03mmol) ofdisodiumhydrogen
phosphate-1 dihydrate, and a pH of the reaction mixture was adjusted to pH 0.5 by using
phosphoric acid. An inner temperature of the reaction mixture was maintained from
84 to 85°C, and 70.0 g (1.24 mol) of 60% aqueous hydrogen peroxide was added
dropwise to the mixture with 247 mmol/hr, while maintaining the pH of the reaction
mixture to 0.01 to 0.08. After completion of the dropwise addition, the mixture was
reacted for further one hour.
After completion of the reaction, when the organic layer solution of the
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the reaction yield of piperonal was 80.0% (Conversion rate of piperonyl
alcohol: 86.0%).
[0060]
Example 3 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; 1.0 to 2.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 215 g of toluene, 124.0
g (815 mmol) of piperonyl alcohol, 2.98 g (12.3 mmol) of sodium molybdatedihydrate
(Na2MoCv2H20), 4.18 g (12.3 mmol) of tetrabutyl ammonium hydrogen sulfate and
18.0 g of water. Then, to the mixture were added 0.50 g (3.21 mmol) of sodium
dihydrogen phosphate-dihydrate and 1.77 g (4.94 mmol) of disodium hydrogen
phosphate-1 dihydrate, and a pH of the reaction mixture was adjusted to pH 1.5 by using
phosphoric acid. An inner temperature of the reaction mixture was maintained from
84 to 85°C, and 70.0 g (1.24 mol) of 60% aqueous hydrogen peroxide was added
dropwise to the mixture with 247 mmol/hr while maintaining the pH of the reaction
mixture to 1.0 to 2.0. After completion of the dropwise addition, the mixture was
reacted for further one hour.
After completion of the reaction, when the organic layer solution of the
17
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the reaction yield of piperonal was 95.0% (Conversion rate of piperonyl
alcohol: 97.3%).
[0061]
Example 4 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; pH 2.0 to 4.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 213 g of toluene, 123.0
g (808 mmol) of piperonyl alcohol, 2.98 g (12.3 mmol) of sodium molybdate-dihydrate
(Na2Mo(V2H20), 4.18 g (12.3 mmol) of tetrabutyl ammonium hydrogen sulfate and
17.0 g of water. Then, to the mixture were added 0.50 g (3.21 mmol) of sodium
dihydrogen phosphate-dihydrate and 1.77 g (4.94 mmol) of disodhim hydrogen
phosphate-1 dihydrate, and the pH of the reaction mixture was adjusted to pH 2.5 by
using phosphoric acid. An inner temperature of the reaction mixture was maintained
from 84 to 85°C, and 70.0 g (1.24 mol) of 60% aqueous hydrogen peroxide was added
dropwise to the mixture with 247 mmol/hr, while maintaining the pH of the reaction
mixture to 2.02 to 4.05. After completion of the dropwise addition, the mixture was
reacted for further one hour.
After completion of the reaction, when the organic layer of the resulting
reaction mixture was quantitatively analyzed by HPLC (absolute calibration method),
then, the reaction yield of piperonal was 97.0% (Conversion rate of piperonyl alcohol:
99.6%).
[00621
Example 5 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; 6.0 to 7.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature controller,
a dropping device and a stirring device were charged 213 g of toluene, 127.5 g (838
mmol) of piperonyl alcohol, 3.07 g (12.7 mmol) of sodium molybdate-dihydrate
(Na2MoCv2H20), 4.31 g (12.7 mmol) of tetrabutyl ammonium hydrogen sulfate and
18.0 g of water. Then, to the mixture were added 0.50 g (3.21 mmol) of sodium
dihydrogen phosphate-dihydrate and 1.77 g (4.94 mmol) of disodium hydrogen
phosphate-1 dihydrate, and the pH of the reaction mixture was adjusted to pH 6.3 by
using 8N aqueous sodium hydroxide solution. An inner temperature of the reaction
mixture was maintained from 84 to 85°C, and 56.8 g (1.00 mol) of 60% aqueous
hydrogen peroxide was added dropwise to the mixture with 251 mmol/hr, while
maintaining the pH of the reaction mixture to 6.0 to 7.0 by using 8N aqueous sodium
18
hydroxide solution. After completion of the dropwise addition, the mixture was
reacted for further one hour.
After completion of the reaction, when the organic layer solution of the
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the reaction yield of piperonal was 99.0% (Conversion rate of piperonyl
alcohol: 100.0%).
[0063]
Example 6 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; 8.0 to 9.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 213 g of toluene, 126.0
g (828 mmol) of piperonyl alcohol, 3.09 g (12.8 mmol) of sodium molybdate-dihydrate
(Na2Mo04*2H20), 4.18 g (12.3 mmol) of tetrabutyl ammonium hydrogen sulfate and
17.0 g of water. Then, to the mixture were added 0.50 g (3.21 mmol) of sodium
dihydrogen phosphate-dihydrate and 1.77 g (4.94 mmol) of disodium hydrogen
phosphate-1 dihydrate, and a pH of the reaction mixture was adjusted to pH 8.6 by using
8N aqueous sodium hydroxide solution. An inner temperature of the reaction mixture
was maintained from 84 to 85°C, and 70.0 g (1.24 mol) of 60% aqueous hydrogen
peroxide was added dropwise to the mixture with 247 mmol/hr while maintaining the
pH of the reaction mixture to 8.0 to 9.0 by using 8N aqueous sodium hydroxide
solution. After completion of the dropwise addition, the mixture was reacted for
further one hour
After completion of the reaction, when the organic layer solution of the
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the reaction yield of piperonal was 94.0% (Conversion rate of piperonyl
alcohol: 98.0%).
[0064]
Comparative example 1 (Synthesis of piperonal using a molybdenum compound:
sodium molybdate was used, pH value of the reaction solution; 10 to 11)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 224 g of toluene, 127.5
g (838 mmol) of piperonyl alcohol, 3.08 g (12.7 mmol) of sodium molybdate-dihydrate
(Na2Mo04-2H20), 4.30 g (12.7 mmol) of tetrabutyl ammonium hydrogen sulfate and
18.0 g of water. Then, to the mixture were added 0.80 g (5.13 mmol) of sodium
dihydrogen phosphate-dihydrate and 2.05 g (5.72 mmol) of disodium hydrogen
phosphate! dihydrate, and a pH of the reaction mixture was adjusted to pH 10.5 by
19
using 8N aqueous sodium hydroxide solution. Next, an inner temperature of the
reaction mixture was maintained from 94 to 95°C, and 71.0 g (1.25 mol) of 60%
aqueous hydrogen peroxide was added dropwise to the mixture with 251 mmol/hr,
while maintaining the pH of the reaction mixture to 10.07 to 10.96 by using 8N aqueous
sodium hydroxide solutioa After completion of the dropwise addition, the mixture
was reacted for further one hour.
After completion of the reaction, when the organic layer solution of the
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the reaction yield of piperonal was 67.8% (Conversion rate of piperonyl
alcohol: 74.2%).
[0065]
Example 7 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, pH value of the reaction solution; 6.0 to 7.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 38 g of toluene, 20.0 g
(131 mmol) of piperonyl alcohol, 0.65 g (2.69 mmol) of sodium molybdate-dihydrate
(Na2Mo(V2H20), 0.91 g (2.68 mmol) of tetrabutyl ammonium hydrogen sulfate and
2.5 g of water. Then, to the mixture were added 0.11 g (0.71 mmol) of sodium
dihydrogen phosphate-dihydrate and 0.33 g (0.92 mmol) of disodium hydrogen
phosphate* 1 dihydrate, and a pH of the reaction mixture was adjusted to pH 6.0. An
inner temperature of the reaction mixture was maintained from 75 to 79°C, 7.7 ml (158
mmol) of 60% aqueous hydrogen peroxide was added dropwise to the mixture, while
maintaining the pH of the reaction mixture to pH 6.0 to 7.0 by using 8 mol/L aqueous
sodium hydroxide solutioa The reaction was stopped when 91 % of the starting
material, piperonyl alcohol was consumed.
After completion of the reaction, when the organic layer of the resulting
reaction mixture was quantitatively analyzed by HPLC (absolute calibration method),
then, the reaction yield of piperonal was 88.0%.
[0066]
Example 8 (Synthesis of piperonal using a molybdenum compound: molybdenum
hexacarbonyl was used, pH value of the reaction solution; 6.0 to 7.0)
In the same manner as in Example 7 using the same amounts of reagents, the
reaction was carried out except for changing sodium molybdate-dihydrate to
molybdenum hexacarbonyl (Mo(CO)g), and the reaction was stopped when 87% of the
starting material, piperonyl alcohol was consumed. After completion of the reaction,
when the organic layer solution of the resulting reaction mixture was quantitatively
20
analyzed by HPLC (absolute calibration method), then, the reaction yield of piperonal
was 84.0%.
[0067]
Example 9 (Synthesis of piperonal using a molybdenum compound: molybdenum
trioxide was used, pH value of the reaction solution; 6.0 to 7.0)
In the same manner as in Example 7 using the same amounts of reagents, the
reaction was carried out except for changing sodium molybdate-dihydrate to
molybdenum trioxide (M0O3), and the reaction was stopped when 72% of the starting
material, piperonyl alcohol was consumed. After completion of the reaction, when the
organic layer solution of the resulting reaction mixture was quantitatively analyzed by
HPLC (absolute calibration method), then, the reaction yield of piperonal was 72.0%.
[0068]
Example 10 (Synthesis of piperonal using a molybdenum compound: molybdenum
dioxide was used, pH value of the reaction solution; 6.0 to 7.0)
In the same manner as in Example 7 using the same amounts of reagents, the
reaction was carried out except for changing sodium molybdate-dihydrate to
molybdenum dioxide (M0O2), and the reaction was stopped when 92% of the starting
material, piperonyl alcohol was consumed. After completion of the reaction, when the
organic layer solution of the resulting reaction mixture was quantitatively analyzed by
HPLC (absolute calibration method), then, the reaction yield of piperonal was 89.0%.
[0069]
Example 11 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, without solvent, pH value of the reaction solution; 6.0 to 7.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 126.0 g (828 mmol) of
piperonyl alcohol, 1.03 g (4.26 mmol) of sodium molybdate-dihydrate (Na2Mo(V-
2H2O), 1.46 g (4.30 mmol) of tetrabutyl ammonium hydrogen sulfate and 18.0 g of
water. Then, to the mixture were added 0.60 g (3.85 mmol) of sodium dihydrogen
phosphate-dihydrate and 2.05 g (5.72 mmol) of disodium hydrogen phosphate-1
dihydrate, and a pH of the reaction mixture was adjusted to pH 6.5 by using 8 mol/L
aqueous sodium hydroxide solution. Next, an inner temperature of the reaction
mixture was maintained from 84 to 85°C, and 61.0 g (1.08 mol) of 60% aqueous
hydrogen peroxide was added dropwise to the mixture with 269 mmol/hr, while
maintaining the pH of the reaction mixture to 6.0 to 7.0 by using 8N aqueous sodium
hydroxide solution. After completion of the dropwise addition, the mixture was
reacted for further one hour.
21
After completion of the reaction, when the organic layer solution of the
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the reaction yield of piperonal was 96.0% (Conversion rate of piperonyl
alcohol: 99.4%).
[0070]
Example 12 (Synthesis of piperonal using a molybdenum compound: sodium molybdate
was used, no buffer (a phosphoric acid compound), pH value of the reaction solution;
6.0 to 7.0)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 125.0 g (822 mmol) of
piperonyl alcohol, 2.98 g (12.3 mmol) of sodium molybdatedihydrate (NaaMoCV-
2H2O), 4.19 g (12.3 mmol) of tetrabutyl ammonium hydrogen sulfate and 18.0 g of
water, and a pH of the reaction mixture was adjusted to pH 6.5 by using 8 mol/L
aqueous sodium hydroxide solution. Next, an inner temperature of the reaction
mixture was maintained from 84 to 85°C, 70.0 g (1.25 mol) of 60% aqueous hydrogen
peroxide was added dropwise to the mixture with 247 mmol/hr, while maintaining the
pH of the reaction mixture to 6.0 to 7.0 by using 8N aqueous sodium hydroxide
solution. After completion of the dropwise addition, the mixture was reacted for
further one hour.
After completion of the reaction, the organic layer solution of the resulting
reaction mixture was quantitatively analyzed by HPLC (absolute calibration method),
then, the reaction yield of piperonal was 95.0% (Conversion rate of piperonyl alcohol:
99.9%).
[0071]
Comparative example 2 (Synthesis of piperonal using a molybdenum compound:
sodium molybdate was used, no at least one salt selected from a quaternary ammonium
salt and an organic phosphonium salt, pH value of the reaction solution; 6.0 to 7.0)
In the same manner as in Example 5 using the same amounts of reagents, the
reaction was carried out except for not using at least one salt selected from a quaternary
ammonium salt and an organic phosphonium salt. After completion of the reaction,
when the organic layer solution of the resulting reaction mixture was quantitatively
analyzed by HPLC (absolute calibration method), then, no piperonal was obtained
(Conversion rate of piperonyl alcohol: 6.0%).
[0072]
Comparative example 3 (Synthesis of piperonal using a molybdenum compound; see
operation method of Patent Literature 1: JP HI 1-158107A)
22
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 1.21 g (5.00 mmol) of
sodium molybdate-dihydrate (Na2MoCv2H20), 1.70 g (5.00 mmol) of tetrabutyl
ammonium hydrogen sulfate and 90.0 g (794 mmol) of 30% aqueous hydrogen
peroxide, and the mixture was vigorously stirred at room temperature for 10 minutes.
Then, to the mixture was added dropwise 220 mL of a toluene solution containing 76.0
g (500 mmol) of piperonyl alcohol (a pH of the reaction mixture at this time was 0.1).
After completion of the dropwise addition, the reaction mixture was stirred at 70°C for
5 hours. After completion of the reaction, when the organic layer solution of the
resulting reaction mixture was quantitatively analyzed by HPLC (absolute calibration
method), then, the yield of the objective material, piperonal was only 15.2%
(Conversion rate of piperonyl alcohol: 43.5%).
[0073]
Example 13 (Synthesis of piperonal using a tungsten compound: sodium tungstate was
used, pH value of the reaction solution; 5.5 to 6.5)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 220 ml of xylene, 76.01
g (500 mmol) of piperonyl alcohol, 1.65 g (5.0 mmol) of sodium tungstate-dihydrate
(Na2WC>4-2H20), 1.70 g (5.0 mmol) of tetrabutyl ammonium hydrogen sulfate and 9.42
g of water. Then, to the mixture were added 2.34 g (1.6 mmol) of sodium dihydrogen
phosphate-dihydrate and 3.56 g (1.0 mmol) of disodium hydrogen phosphate-1
dihydrate, and a pH of the reaction mixture was adjusted to pH 6.0. Next, an inner
temperature of the reaction mixture was maintained from 94 to 95°C, 48.0 ml (991
mmol) of 60% aqueous hydrogen peroxide was added dropwise to the mixture with 141
mmol/hr, while maintaining the pH of the reaction mixture to 5.5 to 6.5 by using 8
mol/L aqueous sodium hydroxide solution. After completion of the reaction, the
resulting reaction mixture was cooled to room temperature, and the organic layer was
separated as a solution. The resulting organic layer solution was washed with 80 mL
of 1 mol/L aqueous sodium hydroxide solution, and the solvent, xylene was distilled off
with (1.3 kPa/132°C) to obtain 67.7 g of piperonal as white solid (yield: 89.3%, based
on piperonyl alcohol).
The physical properties of the resulting compound (piperonal) were as follows.
HPLC purity 94.9% (measured wavelength: 256 nm)
MS spectrum (CI-MS); 151 [M]+.
'H-NMR spectrum (300 mHz, CDC13) 8 (ppm); 6.07 (2H, s), 6.93 (1H, d, J=7.8Hz),
7.32 (1H, d, J=1.5Hz), 7.40, 7.42 (1H, dd, J=1.5Hz), 9.81 (1H, s).
23
[00741
Example 14 (Synthesis of piperonal using a tungsten compound: sodium tungstate was
used, pH value of the reaction solution; 6.0 to 7.0)
In the same manner as in Example 13 using the same amounts of reagents, the
reaction was carried out except for changing sodium tungstate-dihydrate to tungstic acid
(hydrogen tetraoxotungstic(VI) acid; H2WO4), and the reaction was stopped when 70%
of the starting material, piperonyl alcohol was consumed. After completion of the
reaction, when the organic layer solution of the resulting reaction mixture was quantitatively
analyzed by HPLC (absolute calibration method), the yield of piperonal was
69.0%.
[0075]
Example 15 (Synthesis of piperonal using a tungsten compound: sodium tungstate was
used, pH value of the reaction solution; 6.0 to 7.0)
In the same manner as in Example 13 using the same amounts of reagents, the
reaction was carried out except for changing sodium tungstate-dihydrate to tungsten
trioxide (WO3), and the reaction was stopped when 74% of the starting material,
piperonyl alcohol was consumed. After completion of the reaction, when the organic
layer solution of the resulting reaction mixture was quantitatively analyzed by HPLC
(absolute calibration method), the yield of piperonal was 71.0%.
[0076]
Example 16 (Synthesis of piperonal using a tungsten compound: using sodium
tungstate, pH value of the reaction solution; 7.0)
In the same manner as in Example 13 using the same amounts of reagents, the
reaction was carried out except for changing the pH value of the reaction mixture to 7.0
by using 8 mol/L aqueous sodium hydroxide solution. After completion of the
reaction, when the organic layer solution of the resulting reaction mixture was quantitatively
analyzed by HPLC (absolute calibration method), the yield of piperonal was
95.4%.
[0077]
Example 17 (Synthesis of piperonal using a tungsten compound: pH value of the
reaction solution; 3.0)
In the same manner as in Example 13 using the same amounts of reagents, the
reaction was carried out except for changing the pH value of the reaction mixture to 3.0
by using phosphoric acid and sodium dihydrogen phosphate. After completion of the
reaction, when the organic layer solution of the resulting reaction mixture was quantitatively
analyzed by HPLC (absolute calibration method), the yield of piperonal was 54.5%.
[0078]
Comparative example 4 (Synthesis of piperonal using a tungsten compound; using
sodium tungstate, pH value of the reaction solution: 9.0)
In the same manner as in Example 13 using the same amounts of reagents, the
reaction was carried out except for changing the pH value of the reaction mixture to 9.0
by using 8 mol/L aqueous sodium hydroxide solution. After completion of the
reaction, when the organic layer solution of the resulting reaction mixture was quantitatively
analyzed by HPLC (absolute calibration method), the yield of piperonal was
only 21.7%.
[0079]
Comparative example 5 (Synthesis of piperonal using a tungsten compound; using
sodium tungstate, pH value of the reaction solution: 1.0)
In the same manner as in Example 13 using the same amounts of reagents, the
reaction was carried out except for changing the pH value of the reaction mixture to 1.0
by using phosphoric acid. When the organic layer solution of the resulting reaction
mixture was quantitatively analyzed by HPLC (absolute calibration method), then, the
yield of piperonal was only 38.4%.
[0080]
Example 18 (Synthesis of piperonal using a tungsten compound; using sodium
tungstate, using tetrabutyl ammonium chloride as a quaternary ammonium salt)
In a glass-made reaction vessel equipped with a thermometer, a temperature
controller, a dropping device and a stirring device were charged 220 ml of xylene, 76.00
g (500 mmol) of piperonyl alcohol, 1.65 g (5.0 mmol) of sodium tungstate-dihydrate
(Na2WCv2H20), 1.39 g (5.0 mmol) of tetrabutyl ammonium chloride and 9.42 g of
water. Then, to the mixture were added 2.34 g (1.6 mmol) of sodium dihydrogen
phosphate-dihydrate and 3.56 g (1.0 mmol) of disodium hydrogen phosphate-1
dihydrate, and a pH of the reaction mixture was adjusted to pH 6.0. Next, an inner
temperature of the reaction mixture was maintained from 94 to 95°C, 48.0 ml (991
mmol) of 60% aqueous hydrogen peroxide was added dropwise with 141 mmol/hr,
while maintaining the pH of the reaction mixture to 5.5 to 6.5 by using 8 mol/L aqueous
sodium hydroxide solution. After completion of the reaction, the resulting reaction
mixture was cooled to room temperature, and the organic layer was separated as a
solution. When the organic layer of the resulting reaction mixture was quantitatively
analyzed by HPLC (absolute calibration method), then the yield of piperonal was 69.8
g, and the reaction yield was 93.0%.

CLAIMS
1. A process for preparing an aromatic aldehyde compound represented by the
formula (2);
[Formula 5]
.CHO (2)
(R)n-
(wherein R represents a halogen atom, a hydrocarbon group having 1 to 12 carbon
atoms, an alkyloxy group having 1 to 12 carbon atoms, a phenyloxy group, a naphthyloxy
group, a benzyloxy group or a phenethyloxy group, each group of which may have
a substituent(s); n is an integer of 0 to 5; and when n is 2 or more, Rs may form a ring
by combining with each other)
which comprises reacting an aromatic methyl alcohol compound represented by the
formula (1);
[Formula 4]
CH2OH
(D
(wherein R and n have the same meanings as defined above.)
and a peroxide under a pH value of a reaction solution being pH 0.01 or higher and less
than 10, in the presence of at least one metallic compound selected from a molybdenum
compound and a tungsten compound and at least one salt selected from a quaternary
ammonium salt and an organic phosphonium salt.
2. A process for preparing an aromatic aldehyde compound represented by the
formula (2);
[Formula 7]
rrCH0 <2>
(wherein R and n have the same meanings as defined above)
32
13. The preparation process according to any one of Claims 1 to 12, wherein the
phosphoric acid compound is at least one compound selected from phosphoric acid
(orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid), sodium phosphate,
potassium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate,
potassium monohydrogen phosphate, potassium dihydrogen phosphate, and ammonium
phosphate.
14. The preparation process according to any one of Claims 1 to 13, wherein the pH is
adjusted by at least one compound selected from a hydroxide of an alkali metal, a
hydroxide of an alkaline earth metal, a carbonate of an alkali metal, a carbonate of an
alkaline earth metal, a phosphate of an alkali metal and a phosphate of an alkaline earth
metal, phosphoric acid, hydrochloric acid and sulfuric acid.
15. The preparation process according to any one of Claims 1 to 14, wherein the
reaction is carried out without solvent.
16. A process for preparing an aromatic aldehyde compound substantially as herein described with
reference to the foregoing description, examples and the accompanying table.