JPH1135511A - Production of aromatic aldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound in a high yield, by reacting a specific aromatic bisalkoxymethyl compound with nitrogen dioxide. SOLUTION: An aromatic bisalkoxymethyl compound of formula I (R is phenylene group, etc.; R<1> is a 1-4C alkyl) (e.g. dimethoxymethylbiphenyl) in an amount of 1 mol is reacted with preferably 0.1-20 mols of nitrogen dioxide to give an aromatic dialdehyde. The compound of formula I in an amount of 1 mol is reacted with preferably 0.1-1.0 mol of nitrogen dioxide and the conversion of an aromatic bisalkoxymethyl compound is suppressed to <=60% to give an aromatic monoaldehyde [e.g. a formyl(alkoxymethyl) biphenyl of formula II (R<2> is a 1-4C alkyl)]. The compound of formula II is a new compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to pharmaceuticals, agricultural chemicals, dyes,
The present invention relates to a method for producing an aromatic aldehyde useful as a raw material for a liquid crystal polymer.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed for obtaining an aromatic aldehyde from an aromatic alkoxymethyl compound. For example, J. Org.Chem., 42 , 3097 (1977) discloses a method of synthesizing benzaldehyde by oxidizing benzyl methyl ether with nitronium tetrafluoroborate, and Tetrahedron Lett., 27 , 3397 (1977) , 4-methoxy-1-oxo-2,2,6,6-tetramethylpyridinium bromide or a method of oxidation with an oxoammonium salt such as chloride, J. Org.Chem., 54 , 3001 (1989) discloses that nitric acid A method of oxidizing a metal salt of nitric acid such as copper or zinc nitrate supported on silica gel is described in Can.J. Chem., 67 , 699 (1989), which discloses 2,3-dichloro-5,6-cyanobenzoquinone. And the like. However, these methods are problematic in that the oxidizing agent used is not easy to handle due to its corrosiveness and hygroscopicity, must be used in an equivalent amount or more to the raw materials, or is very expensive. Which is not feasible as an industrial production method. As a method for solving these problems, a method for producing a corresponding aromatic aldehyde compound by oxidizing a benzyl alkyl ether with nitrogen dioxide (Japanese Patent Laid-Open No. 7-3306)
No. 55) has been proposed. However, in this method, the substituent on the aromatic ring of the raw material is limited to only those stable to the reaction, and the aromatic aldehyde from the aromatic bisalkoxymethyl compound having two alkoxymethyl groups in the substituent is limited. The synthesis was not particularly known.

[0003]

The present invention solves the above-mentioned problems of the prior art, and provides a new method for producing an aromatic dialdehyde, a method for producing an aromatic monoaldehyde with a high selectivity, Further, the present invention provides a novel substance, formyl (alkoxymethyl) biphenyl.

[0004]

Means for Solving the Problems The first invention has a general formula (1)

Embedded image (In the formula, R represents a phenylene group, a biphenylene group, a naphthalene group, a divalent diphenyl ether residue or a divalent diphenylmethane residue, and R ¹ represents an alkyl group having 1 to 4 carbon atoms.) The present invention relates to a method for producing an aromatic aldehyde, which comprises reacting an aromatic bisalkoxymethyl compound with nitrogen dioxide to produce an aromatic dialdehyde.

The second invention is based on 1 mole of the aromatic bisalkoxymethyl compound represented by the aforementioned general formula (1).
The present invention relates to a method for producing an aromatic aldehyde, which comprises reacting 0.1 to 1.0 mol of nitrogen dioxide to suppress the conversion of an aromatic bisalkoxymethyl compound to 60% or less to produce an aromatic monoaldehyde.

[0006] The third invention is a compound represented by the general formula (2)

Embedded image (Wherein R ² represents an alkyl group having 1 to 4 carbon atoms).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the first or second invention, R of the aromatic bisalkoxymethyl compound represented by the aforementioned general formula (1) is a phenylene group, a biphenylene group, a naphthalene group, a divalent diphenyl ether Residue or divalent diphenylmethane residue,

[0008]

Embedded image And so on. As R ¹ of the first or second invention, a group having 1 carbon atom such as a methyl group, an ethyl group, a propyl group, a butyl group, etc.
And 4 alkyl groups.

The raw materials used in the first or second invention include, for example, dialkoxymethylbenzenes such as o-dimethoxymethylbenzene, p-dimethoxymethylbenzene, m-dipropoxymethylbenzene, and 4,4 ′ Dialkoxymethylbiphenyls such as -dimethoxymethylbiphenyl and 2,4'-dimethoxymethylbiphenyl, 1,5-dimethoxymethylnaphthalene, 4,4'-dimethoxymethylbiphenylether, and 4,4'-diethoxymethyldiphenylmethane And dimethoxymethylbiphenyl is particularly preferred.

Although pure nitrogen dioxide may be used, nitric oxide may be mixed with oxygen, a mixed gas of oxygen and nitrogen or air, and then blown into the reaction system.

The amount of nitrogen dioxide used in the production of the aromatic dialdehyde according to the first invention is preferably 0.1 to 20 mol per mol of the starting aromatic bisalkoxymethyl compound, and particularly preferably 1.5 to 20 mol. Further, 3 to 15 mol is preferable.

The amount of nitrogen dioxide used in the production of the aromatic monoaldehyde according to the second invention may be 0.1 to 2.0 mol, preferably 0.1 to 1.0 mol, per mol of the starting aromatic bisalkoxymethyl compound. .

The first or second invention is preferably a method in which nitrogen dioxide is added to a raw material or a solution of the raw material in an organic solvent in the presence or absence of a solvent. At that time, the reaction temperature is 0 to 1
The temperature is 50 ° C, preferably 0 to 90 ° C.

As a method of adding nitrogen dioxide, a method of adding the whole amount from the beginning, a method of blowing a small amount into a raw material or a raw material dissolved in an organic solvent directly or together with an inert gas such as nitrogen, A method of dropping the organic solvent solution little by little can be used, and it can be appropriately selected depending on the raw material form.

The organic solvent that can be used is not particularly limited as long as it does not hinder the reaction. Specifically, aromatic solvents such as benzene, toluene and the like, and carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloroethane and the like can be used. Examples thereof include lower fatty acids such as hydrocarbons, acetic acid, and propionic acid. These solvents may be used as a mixture of two or more.

The amount of the solvent used is preferably 0 to 50 times, more preferably 3 to 30 times the weight of the aromatic bisalkoxymethyl compound as the raw material. If the solvent is used in an amount of 50 times by weight or more, the reaction is slow, and it is not preferable from the viewpoint of productivity.

In the first or second invention, an acid catalyst can be used to accelerate the reaction and shorten the reaction time. Examples of the acid catalyst include mineral acids such as sulfuric acid, phosphoric acid, and hydrochloric acid; sulfonic acids such as p-toluenesulfonic acid, n-dodecylbenzenesulfonic acid, and trifluoromethanesulfonic acid; phosphotungstic acid, phosphomolybdic acid, silicotungstic acid, and the like. Zeolite (H-type ZS)
M-5), amorphous silica alumina, titanosilicate (such as TS-1), activated clay, and solid acids such as acid-type ion exchange resins. These catalysts may be used as a mixture of two or more. Although the amount of the catalyst used may be large, it is preferably not more than 1 time by weight with respect to the raw material in consideration of economy.

In the second invention, 0.1 to 1.0 mol of nitrogen dioxide is reacted with 1 mol of the starting aromatic bisalkoxymethyl compound, and the conversion of the starting aromatic bisalkoxymethyl compound is 60% or less, Preferably, the content is controlled to 30% or less, and aromatic monoaldehyde such as formyl (alkoxymethyl) biphenyl represented by the above-mentioned general formula (2) can be produced with high selectivity. For example, in the second invention, using 4,4'-bismethoxymethylbiphenyl as a starting material, the conversion of 4,4'-bismethoxymethylbiphenyl is suppressed to 60% or less, particularly 30% or less, whereby 4- Holmill
-4'-methoxymethylbiphenyl can be produced in an amount of 90 mol% or more, and in some cases, 99 mol% or more. At this time,
Most of the products other than formyl-4'-methoxymethylbiphenyl are 4,4'-diformylbiphenyl.

After completion of the reaction, the resulting reaction mixture is treated by a conventional method such as extraction, distillation, crystallization, etc., to obtain the desired aromatic aldehyde.

The formyl (alkoxymethyl) biphenyl represented by the general formula (2) of the third invention is a novel compound which can be confirmed by mass spectrometry, NMR (CDCl ₃ ), IR (KBr method), etc. It is. R ² is a methyl group,
Examples thereof include an alkyl group having 1 to 4 carbon atoms such as an ethyl group, a propyl group, and a butyl group. For example, 4-formyl-4′-methoxymethylbiphenyl has a melting point of 89.6 ° C., the parent peak (226) by mass spectrometry in FIG. 1, and the methyl group proton (3H) by ¹ H-NMR (CDCl ₃ ) in FIG. , 3.4 ppm), methylene group proton (2
H, 4.5 ppm), biphenylene group proton (8H, 7.4-8.0 pp
m), formyl group proton (1H, 10.1 ppm) and IR (KBr
This is a novel compound having the physical properties shown by COO stretching (1704.7 cm ⁻¹ ) according to (method).

[0021]

The present invention will be specifically described below with reference to examples.

Example 1 A 200 ml three-necked flask equipped with a thermometer, a condenser, and a dropping funnel was charged with 5.0 g of 4,4'-dimethoxymethylbiphenyl (2 g).
0.7 mmol) and p-toluenesulfonic acid 1.0 g, 100 ml
In 1,2-dichloroethane. To this solution, 25 ml of a solution of nitrogen dioxide 10 g (227 mmol) in 1,2-dichloroethane 20 ml
Was dropped from the dropping funnel in 30 minutes. During this time, the temperature rose to 30 ° C. due to heat generation. After completion of the dropwise addition, the mixture was stirred at 25 to 30 ° C. for 2 hours, and then the products and raw materials in the reaction solution were analyzed by gas chromatography. The raw material 4,4'-dimethoxymethylbiphenyl was converted to 100%, and the selectivity of 4,4'-diformylbiphenyl to 4,4'-dimethoxymethylbiphenyl consumed was 86 mol%.

Examples 2 to 6 The reaction was carried out in the same manner as in Example 1 except that the type and amount of the solvent, the amounts of nitrogen dioxide and p-toluenesulfonic acid added, and the reaction time were changed, and the results shown in Table 1 were obtained. Was.

[0024]

【table 1】

Example 7 Instead of p-toluenesulfonic acid as a catalyst, an amorphous silica-alumina powder (silica-alumina molar ratio Si / A
The reaction was carried out in the same manner as in Example 6, except that 3 g of l = 11) was used. After the reaction for 1 hour, the conversion of 4,4′-dimethoxymethylbiphenyl was 100%, and the selectivity for 4,4′-diformylbiphenyl was 85 mol%.

Example 8 In place of the starting material 4,4'-dimethoxymethylbiphenyl, p-
Using 3.32 g (20 mmol) of dimethoxymethylbenzene, 0.5
Dissolved in 100 ml of acetic acid with g of 50% sulfuric acid. After a mixed gas of nitric oxide (50 ml / min.) And oxygen (25 ml / min.) Was introduced into the mixture at 25 ° C. for 3 hours, the gas blowing was stopped, and the mixture was further stirred at 25 ° C. for 17 hours. The reaction was allowed to proceed. After completion of the reaction, insolubles were filtered off, and acetic acid was distilled off under reduced pressure. Then, after diluting with 20 ml of dichloromethane and washing with 20 ml of water, the product and the raw material were analyzed by gas chromatography. The conversion of p-dimethoxymethylbenzene was 100%, and the selectivity for p-diformylbenzene was 90 mol%.

Example 9 A 200 ml three-necked flask equipped with a thermometer, a condenser, and a dropping funnel was charged with 10.0 g (4,4′-dimethoxymethylbiphenyl) of
1 mmol) and 1.0 g of p-toluenesulfonic acid.
Dissolved in 2-dichloroethane. To this solution was added dropwise a solution of 0.7 g (15 mmol) of nitrogen dioxide in 1,2-dichloroethane (5 ml) at 25 ° C. from a dropping funnel over 15 minutes. During this time, the temperature was 45 due to heat generation.
° C. After completion of the dropwise addition, the mixture was stirred at 25 to 30 ° C. for 3 hours. The products and raw materials in the reaction solution were analyzed by gas chromatography. The main product was separated and purified by column chromatography after washing and concentrating the reaction product with water. As a result, parent peak (226) by mass spectrometry of FIG. 1, ¹ in FIG. 2 H-NMR
(CDCl ₃ ), methyl group proton (3H, 3.4 ppm), methylene group proton (2H, 4.5 ppm), biphenylene group proton (8H,
7.4-8.0 ppm), formyl group proton (1H, 10.1 ppm) and figure
The main product was identified as 4-formyl-4'-methoxymethylbiphenyl because it had physical properties indicated by C = O stretching (1704.7 cm ^-1 ) by IR (KBr method) of 3. (Melting point: 89.
6 ° C). The raw material 4,4'-dimethoxymethylbiphenyl was converted by 22%, and the selectivity for 4-formyl-4'-methoxymethylbiphenyl was 99%.

Example 10 Except that the amount of nitrogen dioxide was changed to 4.8 g (104 mmol),
The reaction was carried out in the same manner as in Example 9. As a result, the raw material 4,4′-dimethoxymethylbiphenyl was converted to 99%, and the selectivity for 4-formyl-4′-methoxymethylbiphenyl was 58 mol%.
Met. At this time, most of the products other than 4-formyl-4'-methoxymethylbiphenyl were 4,4'-diformylbiphenyl.

Example 11 The solvent was chloroform and the addition amount of nitrogen dioxide was 2.9 g (63 mmo).
l) The reaction was carried out in the same manner as in Example 9, except that the reaction time was changed to 5 hours. As a result, the raw material 4,4′-dimethoxymethylbiphenyl was converted by 82%, and the selectivity for 4-formyl-4′-methoxymethylbiphenyl was 80 mol%. At this time, most of the products other than 4-formyl-4'-methoxymethylbiphenyl were 4,4'-diformylbiphenyl.

[0030]

According to the present invention, an aromatic aldehyde compound containing an aromatic dialdehyde can be produced from an aromatic bisalkoxymethyl compound at high selectivity in a short time under inexpensive nitrogen dioxide under mild reaction conditions. And a method for producing an aromatic aldehyde containing an aromatic monoaldehyde as a main component depending on the reaction conditions, and furthermore, a novel substance, formyl (alkoxy) of the general formula (2) Methyl) biphenyl.

[Brief description of the drawings]

FIG. 1 is a diagram showing mass spectrometry of 4-formyl-4′-methoxymethylbiphenyl.

FIG. 2 is a chart showing ¹ H-NMR (CDCl ₃ ) of 4-formyl-4′-methoxymethylbiphenyl.

FIG. 3 is a diagram showing an IR (KBr method) of 4-formyl-4′-methoxymethylbiphenyl.

Claims (7)

[Claims] [Claim 1] The general formula (1) (In the formula, R represents a phenylene group, a biphenylene group, a naphthalene group, a divalent diphenyl ether residue or a divalent diphenylmethane residue, and R ¹ represents an alkyl group having 1 to 4 carbon atoms.) A method for producing an aromatic aldehyde, comprising reacting an aromatic bisalkoxymethyl compound with nitrogen dioxide to produce an aromatic dialdehyde. 2. The method for producing an aromatic aldehyde according to claim 1, wherein the amount of nitrogen dioxide used is 0.1 to 20 mol per 1 mol of the starting aromatic bisalkoxymethyl compound. 3. A starting material aromatic bisalkoxymethyl compound 1
Reacting 1.5 to 20 moles of nitrogen dioxide per mole,
2. The method for producing an aromatic aldehyde according to claim 1, wherein an aromatic dialdehyde is generated. 4. The raw material aromatic bisalkoxymethyl compound is a bisalkoxymethylbiphenyl.
A method for producing the aromatic aldehyde according to the above. 5. A compound of the general formula (1) (In the formula, R represents a phenylene group, a biphenylene group, a naphthalene group, a divalent diphenyl ether residue or a divalent diphenylmethane residue, and R ¹ represents an alkyl group having 1 to 4 carbon atoms.) Reacting 0.1 to 1.0 mol of nitrogen dioxide with respect to 1 mol of the aromatic bisalkoxymethyl compound, and suppressing the conversion of the aromatic bisalkoxymethyl compound to 60% or less to produce an aromatic monoaldehyde. A method for producing an aromatic aldehyde, which is a feature. 6. The raw material aromatic bisalkoxymethyl compound is a bisalkoxymethylbiphenyl.
A method for producing the aromatic aldehyde according to the above. 7. A formyl (alkoxymethyl) biphenyl represented by the general formula (2). Embedded image (In the formula, R ² represents an alkyl group having 1 to 4 carbon atoms.)