JPS638360A - Production of diphenylethylene compound - Google Patents

Abstract

PURPOSE:To easily produce the titled compound useful as a synthetic intermediate for pigment of color-developing recording material having absorption at near-infrared range, in high yield, by oxidizing diphenylethane with lead peroxide in an organic acid. CONSTITUTION:The objective compound of formula I can be produced by reacting a diphenylethane of formula I (R<1>-R<4> are H, alkyl, alkoxyalkyl, cycloalkyl, benzyl or phenyl; R<5> and R<6> are alkyl, alkoxy or halogen; R<1> and R<2> or R<3> and R<4> may together form pyrrolidino or piperidino) with lead peroxide at about 60 deg.C in an organic acid, preferably in an aqueous solution of formic acid or acetic acid. The organic acid is used at an amount of 5-10 times mol based on the compound of formula I preferably in the form of an aqueous solution having a concentration of 5-10wt%. The lead peroxide is preferably fine powder as much as possible and the amount is more than stoichiometric amount based on the compound of formula I. It is preferably mixed to the compound of formula I at a stroke at low temperature, preferably near 0 deg.C.

Description

[Detailed description of the invention] [Industrial application field] In recent years, OCR (optical character reader)
Recording materials that absorb in the near-infrared region are strongly desired, as they are increasingly used as input media for computers, and in fields such as pressure copying and heat-sensitive recording paper. For example, bis3.3 derived from diphenylethylene compounds
- (Bis-1,1-(+)-dimethylaminophenyl)ethylene-2) -4,5,6,7-tetrachlorophthalide itself is mostly colorless, but it is an electron acceptor. It has the property of absorbing near-infrared rays when brought into contact and develops color, and is expected to be used as a dye for recording materials with near-infrared absorption. The present invention provides an improved method for producing the diphenylethylene compound, which is extremely important as an intermediate for dyes for color-forming recording materials and has absorption in the near-infrared region as described above.

[Prior art and problems to be solved by the invention] As a method for synthesizing the diphenylethylene compound of the present invention, a method in which a diphenyl ketone compound is reacted with a methyl halide by a Grignard reaction has been known. This is a reaction that strongly dislikes moisture, and the handling of solvents such as metallic magnesium, ethyl ether, and tetrahydrofuran is complicated, making industrial production difficult and economically disadvantageous. Furthermore, a method of oxidizing diphenylalkanes with deoxidized lead in an aqueous solution of mineral acids such as nitric acid, hydrochloric acid, sulfuric acid, etc.
143), but it requires a large amount of mineral acid aqueous solution and has the drawback of extremely low yield. The present invention aims to improve these drawbacks and provide a manufacturing method for industrially easily synthesizing diphenylethylene compounds in high yields.

[Means for solving problems]

As a result of intensive research aimed at improving the shortcomings of conventional synthesis methods, the present inventors have discovered that diphenylethylene compounds can be synthesized extremely easily and in high yield by the production method of the present invention. That is, the general formula (1) is characterized in that the diphenylethane compound represented by the general formula (2) is oxidized with deoxidized lead in an organic acid medium, preferably an aqueous formic acid or acetic acid solution.
This is a method for producing a diphenylethylene compound represented by

The appropriate amount of formic acid or acetic acid used at this time is 5 to 10 times the mole of the diphenylethane compound, and 5 to 1 Qwt.
% concentration aqueous solutions are preferred. Further, it is preferable that lead peroxide is preferably in the form of fine particles, used in a stoichiometric amount or more relative to the diphenylethane compound, and mixed all at once at as low a temperature as possible, preferably around 0°C.

[Effects and operations of the invention]

It will be shown below that the improved production method of the present invention eliminates the conventional drawbacks and is extremely superior in obtaining diphenylethylene compounds easily and in high yields.

That is, when an oxidizing agent is applied to the diphenylmethane compound represented by the general formula (2), it becomes a diphenylcarbinol type compound represented by the general formula (3), which then undergoes an intramolecular dehydration reaction to form the compound represented by the general formula (1). It is known that oxidizing agents commonly used in oxidation reactions, such as dichromate, chromic acid, permanganate, manganese oxide, persulfate, hydrogen peroxide, etc. , oxygen etc. mainly produce decomposition by-products,
Or hardly any oxidation occurs.

Diphenylethylene compounds can only be obtained by oxidation with mineral acid-depleted lead oxide, but overoxidation is significant and
A large amount of benzidine compound is produced as a by-product and the yield is extremely low, making it very impractical. According to the improved production method of the present invention, the organic acids used, especially formic acid aqueous solution or acetic acid aqueous solution, have good solubility in diphenylethane compounds, so that they react quickly with lead peroxide to cause instant oxidation. Can be done. In addition, there are very few decomposition by-products due to peroxidation, such as those seen in oxidation in mineral acids (the dehydration reaction of the generated diphenylcarbinol type compound to the diphenylethylene compound is easily carried out, resulting in a high yield). A diphenylethylene compound can be obtained.As is clear from the above, the present invention provides a manufacturing method for industrially easily synthesizing a diphenylethylene compound at a high yield without using a complicated reaction route that dislikes moisture. I can do it.

Hz [In the formula, H1, R2, R3, p4 represent a hydrogen atom, an alkyl group, an alkoxyalkyl group, a cycloalkyl group, a benzyl group, a phenyl group, and R5, Rh represent an alkyl group,
Indicates an alkoxy group and a halogen atom. Also, R1 and R2,
R3 and R4 may each be bonded together to form a pyrrolidino group or a piperidino group with an adjacent nitrogen atom. ] [Examples, etc.] Next, the advantages of the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example 1 (1-1) Preparation of 1.1-bis(4-dimethylaminophenyl)ethane; 242 g of dimethylaniline and 85% aqueous formic acid solution 5Q Q
Add 110 g of paraldehyde to mIl and keep at 60°C for 30 hours. Add 500 mA of water and make alkaline with caustic soda. The oil was separated from the aqueous layer and recrystallized from methanol to give 185 g of colorless crystals with a melting point of 64-67°C.
get.

(1-2) Synthesis of 1.1-bis(4-dimethylaminophenyl)ethylene; 1.1-bis(4-dimethylaminophenyl)ethane 1
Dissolve 21g in 250mj2 of 85% formic acid aqueous solution,
000mj! Add 1000g of ice and bring to 0°C.

On the other hand, 0.55 mol of finely divided peracid was dispersed in 50 Qml of 0°C water and added all at once while stirring well. After 1 hour, 12g of salt and 200g of 62% sulfuric acid aqueous solution
is added to crystallize lead sulfate, which is then filtered and separated. The filtrate was neutralized with caustic soda, the precipitate was extracted with toluene, the extract was concentrated and recrystallized with methanol, and the melting point was 122~
88 g (66% of theory) of pale yellow-green crystals at 124° C. were obtained.

Example 2 Synthesis of 1.1-bis(4-diethylaminophenyl)ethylene; 149 g of diethylaniline and 25% aqueous formic acid solution
Add 55g of paraaldehyde to ml and incubate at 60℃ for 30 minutes.
Keep time. Add 200 Qml of water and 1000g of ice and bring to 0°C.
The same operation as in Example (1-2) was performed to obtain a melting point of 10.
85 g of pale yellow-green crystals (52% of theory) at 2-104°C
I got it.

Example 3 (3-1) Preparation of 1.1-bis(4-pyrrolidinophenyl)ethane; 294 g of N-phenylpyrrolidine, 400 mβ of water, 62
% sulfuric acid 348 g, I)'-toluenesulfonic acid 1 g,
Add 110 g of balaldehyde and keep at 55°C for 12 hours. Neutralize with caustic soda, separate the oil from the aqueous layer, and recrystallize from toluene to give colorless crystals with a melting point of 110-112°C.
30g was obtained.

(3-2) Synthesis of 1.1-bis(4-pyrrolidinophenyl)ethylene; 1, t-his(4-pyrrolidinophenyl)ethane 159
Dissolve g in 500 ml of 85% formic acid aqueous solution, and add 20 ml of water.
00 ml and 1000 g of ice to bring the temperature to 0°C, and perform the same operation as in Example (1-2) until the melting point was 215-219°C.
84 g (53% of theory) of pale yellow-green crystals were obtained.

Example 4 Synthesis of 1.1-bis(4-piperidinophenyl)ethylene; 147 g of N-phenylpiperidine was treated in the same manner as in Example 2 to obtain 105 g of pale yellow-green crystals with a melting point of 102 to 105°C.
(56% of theory) was obtained.

Example 5 Synthesis of 1.1-bis(4-diethylaminophenyl)ethylene: 250 ml of 85% formic acid aqueous solution was mixed with 25 Qml of glacial acetic acid.
The same operation as in Example 2 was carried out except that the melting point was 12.
80 g of pale yellow-green crystals (60% of theory) at 2-124°C
I got it.

Examples 6 to 13 The corresponding diphenylethane compounds were synthesized using various aminobenzene compounds in place of dimethylaniline in Example (1-1), and then 1,1-bis in Example (1-2) Table 1 shows diphenylethylene compounds obtained by replacing (4-dimethylaminophenyl)ethane with the corresponding diphenylethane compound and oxidizing it with peracid.

Table 1 Comparative Example 1 1.1-bis(4-dimethylaminophenyl)ethane 1
21 g in 2000 ml of water containing 2 moles of nitric acid)
Dissolve, add 1000g of ice and bring to 0℃ Example (1-2)
The same operation as above was carried out, but the oxidation product was 1.1-
Bis(4-dimethylaminophenyl)ethylene was present in very small amounts and could not be isolated.

Comparative Example 2 Comparative Example 1 except that 2 moles of nitric acid was replaced with 2 moles of hydrochloric acid.
The same operation as above was performed, but the oxidation product 1,1-bis(4-dimethylaminophenyl)ethylene was so small that it could not be isolated.

Comparative Example 3 2 000 mj containing 2 moles of nitric acid! water and ice 10
The same operation as in Comparative Example 1 was performed except that 00 g was replaced with 201 g of water and 12.5 kg of ice, but there was very little 1,1-bis(4-dimethylaminophenyl)ethylene as an oxidation product. Could not be isolated.

Claims (1)

[Scope of Claims] [1] Diphenylethylene represented by the general formula (1), which is obtained by oxidizing the diphenylethane compound represented by the general formula (2) using lead peroxide in an organic acid medium. Method of manufacturing the compound. (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R^1, R^2, R^3, R^4 are hydrogen atoms,
It represents an alkyl group, an alkoxyalkyl group, a cycloalkyl group, a benzyl group, a phenyl group, and R^5 and R^6 are
Indicates an alkyl group, an alkoxy group, or a halogen atom. Further, R^1 and R^2, R^3 and R^4 may each be bonded to form a pyrrolidino group or a biperidino group together with an adjacent nitrogen atom. ]