JPS5837395B2 - Method for producing N,N-disubstituted-p-phenylenediamine derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently producing N,N-disubstituted p-phenylenediamine derivatives by reducing N,N-disubstituted p-nitrosoaniline derivatives.

N. N-disubstituted-p-phenylenediamine derivatives are compounds useful as dye intermediates, light-sensitive materials, photographic chemicals, etc., but their synthesis method has conventionally involved using a large amount of N,N-dialkyl-p-nitrosoaniline. A method of reduction using metals and mineral acids is commonly used.

However, this method has the drawback that the waste liquid from the reduction reaction contains metal salts and requires complicated operations to remove them.

The present inventors have developed N, which overcomes the drawbacks of such conventional methods.
As a result of intensive research to develop a method for producing N-disubstituted p-phenylenediamine derivatives, we found that an efficient method for producing N,N-disubstituted p-nitrosoaniline derivatives was achieved by electrolytic reduction of N,N-disubstituted p-nitrosoaniline derivatives. It was discovered that substituted p-phenylenediamine could be produced, and based on this knowledge, the present invention was completed.

That is, the present invention provides a general formula (wherein R1 and R2 are selected from the group consisting of methyl, ethyl, probyl, hydroxymethyl, hydroxyethyl and hydroxyprobyl groups, and R3 is selected from the group consisting of hydrogen methyl and ethyl groups) In reducing the N,N-disubstituted p-nitrosoaniline derivative represented by The present invention provides a method for producing an N,N-disubstituted mono-p-phenylenediamine derivative represented by the formula (wherein R1, R2, and R3 have the same meanings as above).

In the method of the present invention, water or alcohol (lower alcohols such as methanol, ethanol, propanol, etc.) containing sulfuric acid as a supporting electrolyte is charged as a medium into an electrolytic cell having a diaphragm, and the N,N-displacement of the raw material is charged into the cathode chamber. This can be carried out by adding a -p-nitrosoaniline derivative and performing electrolytic reduction while regulating the potential or current.

At this time, the concentration of sulfuric acid as a supporting electrolyte is 0.65-1
0% is good.

As the electrode in the method of the present invention, copper, nickel, stainless steel, iron, zinc, aluminum, Monel alloy, lead, platinum, carbon, brass, etc. are used for the cathode.

Furthermore, carbon, lead, platinum, etc. are used as the anode.

As the reference electrode, a standard silver electrode, a silver monochloride electrode, or the like is used.

The concentration of the starting material N,N-disubstituted p-nitrosoaniline derivative in the cathode chamber is usually 0.3 to 1.2%.

The voltage applied to the cathode in constant potential electrolysis is preferably 0.1 to 0.5 V more negative than the potential that shows a reduction wave.

If the applied voltage is on the positive side of the above range, the reaction will not proceed sufficiently, and if it is more on the negative side, the energy efficiency will decrease.

The current density in constant current electrolysis is 0.001 to o. 0
2 A/i is appropriate.

If the current density is too small, the reaction time becomes long, and if it is too large, the selectivity decreases due to by-products.

The amount of current applied is in the range of 3.5 to 6 faradays/mol relative to the substrate.

The reaction temperature is usually in the range of 10 to 40°C.

N,N- produced as a result of the electrolytic reduction reaction in the method of the present invention
The disubstituted p-phenylenediamine derivative can be separated as a sulfate salt by concentrating the catholyte using a conventional method.

According to the method of the present invention, N,N-disubstituted-p-phenylenediamine derivatives can be obtained in good yield and with high purity through relatively simple operations.

Next, the present invention will be explained in more detail based on examples.

Example 1 0.0% N,N-dimethyl-p-nitrosoaniline was added to the cathode chamber of an electrolytic cell charged with 50,771 liters of a 10% sulfuric acid aqueous solution.
15g was added, the copper plate was used as the cathode, the carbon plate was used as the anode, and the saturated sweetened electrode was used as the reference electrode.While stirring well at room temperature, a voltage of 10.65μ was applied to the cathode relative to the reference electrode.
Constant potential electrolytic reduction was performed by applying a current of 463 coulombs.

After the electrolysis was completed, the catholyte was subjected to diazo titration with a 0.5N normal sodium nitrite solution, and it was found that N,N-dimethyl-pniphenylenediamine was produced in a yield of 80%.

Example 2 0.381 of N-ethyl-N-hydroxyethyl-p-nitrosoaniline was added to the cathode chamber of an electrolytic cell charged with 50 TL of 10% sulfuric acid aqueous solution, and the copper plate was used as the cathode and the platinum plate was used as the anode. While stirring well at room temperature, increase the current density to O.
Constant current electrolytic reduction was performed by applying a current of 772 coulombs using OO5A/Cnl.

As a result of diazo titration of the catholyte with 0.5N sodium nitrite normal solution, N-ethyl-N-hydroxyethyl-p
- Phenylenediamine was found to be viable with a yield of 83%.

Example 3 10% sulfuric acid aqueous solution 71IL and methanol 100d
0.3 g of N,N-dimethyl-p-nitrosoaniline was added to the cathode chamber of the electrolytic cell charged with the above, and the stainless steel plate was used as the cathode and the carbon plate was used as the anode, and the current density was 0.0 while stirring well at room temperature. Constant current electrolytic reduction was carried out by applying a current of 772 coulombs at 0 5 A/ffl.

As a result of diazo titration of the catholyte with a 0.5N sodium nitrite normal solution, it was found that N,N-dimethyl-p-phenylenediamine was produced in a yield of 75%.

Claims (1)

[Claims] 1 General formula (wherein R1 and R2 are selected from the group consisting of methyl, ethyl, probyl, hydroxymethyl, hydroxyethyl and hydroxyprobyl groups, and R3 is hydrogen, methyl and ethyl groups) (selected from the group)! In reducing the N,N-disubstituted-p-nitrosoaniline derivative represented by the general formula (Rl , R2 and R3 have the same meaning as above).