CN109912430B

CN109912430B - Method for synthesizing chloro-p-phenylenediamine

Info

Publication number: CN109912430B
Application number: CN201910176021.1A
Authority: CN
Inventors: 陈新志; 徐泽; 钱超
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-03-08
Filing date: 2019-03-08
Publication date: 2020-07-10
Anticipated expiration: 2039-03-08
Also published as: CN109912430A

Abstract

The invention discloses a synthesis method of chloro-p-phenylenediamine, which sequentially comprises the following steps: adding o-chloro-p-nitroaniline, metal alkoxide and alcohol serving as a solvent into a reaction kettle, mixing, and heating to 100-190 ℃ to react for 2-6 h; cooling the reaction product to room temperature, distilling and recovering the alcohol solvent in the reaction solution, wherein the remainder after recovering the alcohol solvent is a crude product of the chloro-p-phenylenediamine. The method for synthesizing the chloro-p-phenylenediamine avoids the use of a high catalyst, has simple process and less three wastes, and has good industrial application value.

Description

Method for synthesizing chloro-p-phenylenediamine

Technical Field

The invention belongs to the field of chemical industry, and particularly relates to a synthesis method of chloro-p-phenylenediamine.

Background

Chlorinated p-phenylenediamine is an important fine chemical intermediate, and is mainly used for synthesizing dyes and pigments (such as pigment 144). At present, chlorinated p-phenylenediamine is mostly prepared by reduction reaction of aromatic nitro compound (o-chloro-p-nitroaniline or o-chloro-dinitrobenzene), and the following methods are mainly used in industry:

1) chemical reduction process

The chemical reduction method mainly comprises iron powder, hydrazine hydrate, sodium borohydride and other reduction methods. The iron powder has large reduction three wastes which are gradually eliminated at present; sodium borohydride is mainly used in laboratory experiments and is difficult to be applied industrially. In patent CN103274952, hydrazine hydrate is used as a reducing agent, organic matters such as toluene and acetone are used as solvents, and ferric chloride and activated carbon in a certain ratio are used as catalysts to reduce o-chloro-p-nitroaniline into chloro-p-phenylenediamine with a yield of 96.5%.

2) Catalytic hydrogenation reduction process

In patent CN101544571A, Pd/C is used as a catalyst, metal ions are used as a cocatalyst, 95% ethanol is used as a solvent, catalytic hydrogenation of o-chloro-p-nitroaniline is carried out under the hydrogen pressure of 0.3-0.8 MPa and at the temperature of 80-130 ℃, and the yield of the o-chloro-p-phenylenediamine is 85-95%.

In patent CN106748834A, 1, 4-dioxane is used as solvent, 4, 4-dimethoxy-2, 2-bipyridyl silver is used as catalyst, potassium tert-butoxide is used as base, and under the condition of hydrogen pressure of 4Mpa, o-chloro-p-nitroaniline is reduced to o-chloro-p-phenylenediamine, and the product yield is 96% after column chromatography purification.

The catalytic hydrogenation method usually adopts noble metals such as Pt, Ni, Pd, Ag and the like as catalysts, has high cost, and has the defects that the reaction needs to be carried out under high-pressure hydrogen, the reaction conditions are not easy to control, the side reaction of dechlorination is easy to occur and the like.

3) Other reduction processes

At present, other reduction methods exist, such as Journal of Organic Chemistry,79(19),9433-9439, 2014, in which vitamin is used as a reducing agent to reduce o-chloro-p-nitroaniline, the yield is 85%, Organic L-ters, 15(14),3734-3737, 2013, potassium tert-butoxide is used as a base, Pd loaded on an Organic ligand is used as a catalyst, ammonia is dissolved in an Organic solvent, and 4-bromo-2-chloroaniline is directly subjected to amination reaction to generate chloro-p-phenylenediamine, the yield is 79%, and the methods are still in laboratory research and are not applied to industrial production.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for synthesizing chloro-p-phenylenediamine, which is efficient, economical and suitable for industrial production requirements.

In order to solve the technical problems, the invention provides a synthesis method of chloro-p-phenylenediamine, which sequentially comprises the following steps:

1) adding o-chloro-p-nitroaniline, metal alkoxide and alcohol serving as a solvent into a reaction kettle, mixing, and heating to 100-190 ℃ for reaction for 2-6 hours;

metal alkoxide: 0.8-1.4 of o-chloro-p-nitroaniline: 1 in a molar ratio;

2) cooling the obtained product in the step 1) to room temperature, distilling and recovering the alcohol solvent in the reaction solution, wherein the remainder after recovering the alcohol solvent is a crude chloro-p-phenylenediamine product.

Note: the residue contains impurities in addition to the main product chlorinated p-phenylenediamine, including: small amounts of unreacted starting material (o-chloro-p-nitroaniline), excess metal alkoxide, by-product base (e.g. sodium hydroxide), by-product o-chlorophenol, and small amounts of coked high-boiling impurities.

The improvement of the synthesis method of the chloro-p-phenylenediamine further comprises the following step 3): and washing, drying and purifying the crude product of the chlorinated p-phenylenediamine to obtain the chlorinated p-phenylenediamine.

As a further improvement of the synthesis method of the chloro-p-phenylenediamine, in the step 1):

the metal alkoxide is sodium methoxide (preferred), potassium methoxide (preferred), sodium ethoxide, potassium ethoxide and sodium isopropoxide;

the alcohol is methanol, ethanol or isopropanol.

60-200 ml of alcohol is added for every 0.5mol of o-chloro-p-nitroaniline.

metal alkoxide: 1.1-1.4 of o-chloro-p-nitroaniline: 1 in a molar ratio;

the reaction temperature is 150-190 ℃, and the reaction time is 3-6 h.

As a further improvement of the synthesis method of the chloro-p-phenylenediamine, the purification in the step 3) is as follows: adding a purifying reagent into the dried crude chloro-p-phenylenediamine, and heating until the dried crude chloro-p-phenylenediamine is dissolved; and then adding activated carbon, keeping the temperature and decoloring for 0.2-1 h (preferably 0.5h), filtering, cooling the obtained filtrate to 0-5 ℃, and drying the precipitate (drying at 50 +/-10 ℃ to constant weight) to obtain the chloro-p-phenylenediamine.

As a further improvement of the synthesis method of the chloro-p-phenylenediamine, in the step 3):

3 +/-1 g of activated carbon is added for every 100g of the crude chloro-p-phenylenediamine; the purification reagent is lower alcohol, and 60-150 ml of lower alcohol is added for each 100 parts of the crude chloro-p-phenylenediamine. The lower alcohol is methanol or ethanol.

The reaction equation of the present invention is as follows:

the synthesis of the chloro-p-phenylenediamine by the method has the following technical advantages:

1) at present, no synthesis process report for preparing chloro-p-phenylenediamine by using an alcoholic solution of metal alkoxide as a reducing agent exists. In the invention, the reducing agent is metal alkoxide and alcohol, namely, the metal alkoxide and the alcohol act together to reduce, and a catalyst is not required.

2) The metal alkoxide is cheap and easy to obtain, no complex catalyst is needed in the reaction, the process steps are simple, the product post-treatment is convenient, and the three wastes are less.

In conclusion, the method for synthesizing the chloro-p-phenylenediamine avoids the use of expensive catalysts, has simple process and less three wastes, and has good industrial application value.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

example 1, a method of making chloro-p-phenylenediamine, sequentially performing the following steps:

1) 86.3g (0.5mol) of o-chloro-p-nitroaniline, 150ml of methanol and 32.4g (0.6mol) of sodium methoxide are put into a 250ml reaction kettle, the reaction kettle is sealed after air is replaced by nitrogen for a plurality of times, and the temperature is raised to 150 ℃ for heat preservation for 3 hours.

2) And after the reaction in the step 1) is finished, cooling to room temperature, distilling the reaction liquid to recover (collecting fractions at 63-65 ℃) 145ml of methanol, and obtaining about 118.6g of crude chloro-p-phenylenediamine (crude chloro-p-phenylenediamine).

The crude chlorinated p-phenylenediamine contains the following impurities besides the main product chlorinated p-phenylenediamine: a small amount of unreacted raw materials, excessive sodium methoxide, a byproduct sodium hydroxide, a byproduct o-chlorophenol and a small amount of coked high-boiling impurities.

3) Washing the crude chlorinated p-phenylenediamine with deionized water for 3 times (the dosage of the deionized water is 50ml in each washing), drying at 80 ℃ to constant weight, adding the dried crude chlorinated p-phenylenediamine into 100ml of methanol, heating to 70 ℃ to completely dissolve the crude chlorinated p-phenylenediamine, adding 3.0g of active carbon, preserving heat and decoloring for 0.5h, filtering to remove the active carbon while the solution is hot, reducing the filtrate to 0-5 ℃, separating out fine chlorinated p-phenylenediamine, and drying at 50 ℃ to constant weight to obtain 49.1g of fine chlorinated p-phenylenediamine, wherein the yield is 68.9 percent and the purity is 97 percent.

Examples 2 to 5,

Keeping the feeding amount of the o-chloro-p-nitroaniline unchanged, changing the reaction temperature in the step 1) of the embodiment 1, and obtaining the embodiments 2 to 5 respectively under the condition that the rest conditions are identical to the embodiment 1. The specific process parameters and the results are shown in table 1 below:

TABLE 1

Examples	Reaction temperature/. degree.C	Yield/%
			1	150	68.9
2	100	61.0
			3	120	67.5
4	170	68.9
			5	190	68.8

Examples 6 to 9,

Keeping the feeding amount of the o-chloro-p-nitroaniline unchanged, changing the dosage of the alcohol in the step 1) of the embodiment 1, and obtaining the embodiments 6 to 9 respectively under the condition that the rest conditions are equal to the embodiment 1. The specific process parameters and the results are shown in table 2 below:

TABLE 2

Examples	Alcohol dosage/ml	Yield/%
			6	62.1	63.3
7	130	68.6
			8	180	68.5
9	200	68.6

Examples 10 to 14,

The amount of the metal alkoxide in example 1 was changed while keeping the amount of the o-chloro-p-nitroaniline constant, and the other conditions were the same as those in example 1, thereby obtaining examples 10 to 14, respectively. The specific process parameters and the results are shown in table 3 below:

TABLE 3

Examples	Metal alkoxide dosage/g	Yield/%
			10	21.6	40.8
11	27.0	55.3
			12	29.7	63.9
13	35.1	68.8
			14	37.8	68.9

Examples 15 to 18,

The same procedure as in example 1 was repeated except that the kinds of the metal alkoxide and the alcohol in example 1 were changed while keeping the charge amount of o-chloro-p-nitroaniline constant, thereby obtaining examples 15 to 18. The specific process parameters and the results are shown in table 4 below:

TABLE 4

Examples	Metal alkoxides	Amount of metal alkoxide	Alcohol(s)	Yield/%
					15	Potassium methoxide	42.0g(0.6mol)	Methanol	68.4
16	Sodium ethoxide	40.83g(0.6mol)	Ethanol	62.0
					17	Potassium ethoxide	48.70g(0.6mol)	Ethanol	64.3
18	Sodium isopropoxide	49.24g(0.6mol)	Isopropanol (I-propanol)	59.1

Examples 19 to 22,

The reaction time in the example 1 is changed while keeping the charging amount of the o-chloro-p-nitroaniline unchanged, and the rest conditions are the same as the example 1, thereby respectively obtaining the examples 19 to 22. The specific process parameters and the results are shown in table 5 below:

TABLE 5

Examples	Reaction time/h	Yield/%
			19	2	61.7
20	4	68.9
			21	5	68.6
22	6	68.7

The purity of the products obtained in the above examples 2 to 22 was about 97%.

Comparative examples 1,

The solvent in example 1 is changed, the volume dosage is kept unchanged, and the rest conditions are identical to example 1; the specific process parameters and results are shown in table 6 below:

TABLE 6

Note: when the solvent is selected from toluene, ethyl acetate and 1, 4-dioxane, the solvent is recovered by reduced pressure distillation in the step 2).

Comparative examples 2,

Keeping the feeding amount of the o-chloro-p-nitroaniline unchanged, changing the metal alkoxide in the embodiment 1 into the following alkali, and keeping the molar amount of the alkali unchanged; the remaining conditions were identical to those of example 1, and the specific process parameters and results are shown in Table 7 below:

TABLE 7

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.

Claims

1. The synthesis method of the chloro-p-phenylenediamine is characterized by sequentially comprising the following steps of:

metal alkoxide: 0.8-1.4 of o-chloro-p-nitroaniline: 1 in a molar ratio;

the metal alkoxide is sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide and sodium isopropoxide;

the alcohol is methanol, ethanol or isopropanol;

2. The method for synthesizing chloro-p-phenylenediamine according to claim 1, further comprising the following step 3): and washing, drying and purifying the crude product of the chlorinated p-phenylenediamine to obtain the chlorinated p-phenylenediamine.

3. The method for synthesizing chloro-p-phenylenediamine according to claim 1 or 2, wherein in the step 1):

60-200 ml of alcohol is added for every 0.5mol of o-chloro-p-nitroaniline.

4. The method for synthesizing chloro-p-phenylenediamine according to claim 3, wherein in the step 1):

metal alkoxide: 1.1-1.4 of o-chloro-p-nitroaniline: 1 in a molar ratio;

the reaction temperature is 150-190 ℃, and the reaction time is 3-6 h.

5. The method for synthesizing chloro-p-phenylenediamine according to claim 2, wherein the purification in the step 3) is: adding a purifying reagent into the dried crude chloro-p-phenylenediamine, and heating until the dried crude chloro-p-phenylenediamine is dissolved; and then adding activated carbon, keeping the temperature and decoloring for 0.2-1 h, filtering, cooling the obtained filtrate to 0-5 ℃, and drying precipitates to obtain the chloro-p-phenylenediamine.

6. The method for synthesizing chloro-p-phenylenediamine according to claim 5, wherein in the step 3):

3 +/-1 g of activated carbon is added for every 100g of the crude chloro-p-phenylenediamine;

the purification reagent is lower alcohol, and 60-150 ml of lower alcohol is added for every 100g of the crude chloro-p-phenylenediamine.

7. The method for synthesizing chloro-p-phenylenediamine according to claim 6, wherein: the lower alcohol is methanol or ethanol.