CN109320424A

CN109320424A - A kind of purification process of pendimethalin

Info

Publication number: CN109320424A
Application number: CN201710641506.4A
Authority: CN
Inventors: 陈夕鹏; 王晓军; 袁爱菊
Original assignee: Jiangsu Yongan Chemical Co Ltd
Current assignee: Jiangsu Yongan Chemical Co Ltd
Priority date: 2017-07-31
Filing date: 2017-07-31
Publication date: 2019-02-12
Anticipated expiration: 2037-07-31
Also published as: CN109320424B

Abstract

The invention discloses the purification process of pendimethalin, comprise the following steps: 1) putting into container, then acid solution is added in a reservoir pendimethalin crude product, toluene, dichloroethanes；2) stratification, filtering, removing solvent toluene and dichloroethanes；3) molecule rectifying is carried out using molecule rectifying device, further converts nitrosamine and becomes pendimethalin, the pendimethalin after obtaining second of purification；4) pendimethalin after refining to second recrystallizes, and obtains reddish-orange crystals, and centrifugation obtains the pendimethalin after third time refines.

Description

A kind of purification process of pendimethalin

Technical field

The present invention is a kind of method of purification of herbicide, the purification process of specifically a kind of pendimethalin.

Background technique

Pendimethalin (Pendimethalin), English name: Pendimethalin belongs to phenyl amines herbicide, is once called as diformazan Penta happy spirit, trade name apply field and mend, remove bud is logical, weeding is logical, pendimethalin, herbicide are logical, dish grass is logical etc., are by former American Cyanamid Company The phenyl amines herbicide of exploitation.The domestic and international existing production method of pendimethalin raw medicine, for raw material, is passed through with 3,4- dimethyl nitrobenzene Hydrogenation, alkylation, nitrification are made, and the process route step is brief, and construction investment is few, and process recovery ratio is high, and raw material valence is easy to get, and produce It is at low cost, not only generallyd use and the production method of domestic production producer in foreign countries.With 3,4- dimethyl nitrobenzene meter, work Skill total recovery is up to 80%, and thick active compound content is after 80%, purification up to 95% or more.But the technique is in final step 3,4- dimethyl When aniline nitrifies, the pendimethalin of generation can be nitrified further, generate nitrosamine (N- nitroso pendimethalin) by-product, most Up to 20% or more, N- nitroso pendimethalin by-product, not only toxicity is high when high, lures mutation, and because its amount is big, lead to nitre Change yield decline, seriously affect production cost, it is necessary to make its deoxidization, degradation, therefore, which increases purifying refining step.Although Purifying using acidolysis and two methods of hot tearing removing but final products in still have 0.01% or more residual, and national standard be 80PPm(0.008%) below.

Summary of the invention

Goal of the invention: the purpose of the present invention is to solve above-mentioned technical problems, provide a kind of purifying side of pendimethalin Method is reduced to the content of nitrosamine within national standard.

Technical solution: the purification process of pendimethalin of the present invention comprises the following steps:

1) pendimethalin crude product, toluene, dichloroethanes are put into container according to the ratio that mass ratio is 1 ~ 2:1:1.5 ~ 2.5, Acid solution is added in a reservoir again, the acid mass fraction of the acid solution is 10-20%, the acid solution and diformazan penta The mass ratio of clever crude product is 4 ~ 5:5；

2) it is stirred 0.5 ~ 1 hour at a temperature of 60-100 DEG C, stratification, filtering；Solvent toluene and dichloroethanes are removed, is obtained Pendimethalin after refining for the first time；

3) pendimethalin after refining to first time is further purified, and carries out molecule rectifying using molecule rectifying device, further Conversion nitrosamine becomes pendimethalin, the pendimethalin after obtaining second of purification；

4) pendimethalin after refining to second recrystallizes, and reddish-orange crystals is obtained, after centrifugation obtains third time purification Pendimethalin.

Further, acid described in the step 1) is one of phosphoric acid, hydrochloric acid or sulfuric acid.

Further, the process conditions of the step 2 removing solvent are negative pressure 0.098-0.01 MPa, 65-95 DEG C of temperature Degree.

Further, the condition of molecule rectifying is 100-120 DEG C of temperature in the step 3), 0.098 MPa of negative pressure.

Further, the recrystallizing technology of the step 4) are as follows: use methanol or ethanol as a solvent, according to pendimethalin with it is molten The mass ratio of agent is that the ratio of 1:1.5 ~ 2.5 is recrystallized, and stirs 0.5-1 hours and dissolves under the conditions of 50-65 DEG C of temperature, adds Enter to remove toner and active carbon, mother liquor is stirred 0.5 ~ 1 hour at a temperature of -5 ~ 5 DEG C after filtering, obtains reddish-orange crystals.

The utility model has the advantages that the present invention makes Asia using a variety of purification techniques such as filtering, molecule rectifying and recrystallization, multistage purification The content of nitramine is lower than national standard, technical process is simple and environmentally-friendly, at low cost well below 0.001%.

Specific embodiment

In order to deepen the understanding of the present invention, the present invention will be described in further detail with reference to the examples below, the embodiment For explaining only the invention, it is not intended to limit the scope of the present invention..

Embodiment 1

The purification process of pendimethalin, comprises the following steps:

1) pendimethalin crude product, toluene, dichloroethanes are put into container according to the ratio that mass ratio is 1:1:1.5, then held Phosphoric acid solution is added in device, the acid mass fraction of the phosphoric acid solution is 15%, the matter of the acid solution and pendimethalin crude product Amount is than being 1:1；

2) it is stirred 1 hour at a temperature of 90 DEG C, stratification, filtering；Solvent first is removed at a temperature of negative pressure 0.098MPa, 80 DEG C Benzene and dichloroethanes obtain the pendimethalin after refining for the first time；Through detecting, 96% or more pendimethalin content, nitrosamine is dropped to 0.02% or less；

3) pendimethalin after refining to first time is further purified, and carries out molecule rectifying, molecule essence using molecule rectifying device The condition evaporated is 120 DEG C of temperature, 0.098 MPa of negative pressure, further converts nitrosamine and becomes pendimethalin, obtains second of purification Pendimethalin afterwards；Through detecting, 98% or more pendimethalin content, content of nitrosamines is below 0.008%；

4) pendimethalin after refining to second recrystallizes, using methanol as solvent, according to the matter of pendimethalin and solvent Amount is stirred 0.5 hour under the conditions of 55 DEG C of temperature and is dissolved, be added and remove toner and activity than being that the ratio of 1:1.5 is recrystallized Charcoal obtains reddish-orange crystals after filtering by mother liquor 1 hour at a temperature of -5 ~ 5 DEG C, and centrifugation obtains the diformazan after third time refines Penta spirit, yield 95% further decrease the content of nitrosamine, this final product, the content of nitrosamine is well below 0.001%.

Embodiment 2

The purification process of pendimethalin, comprises the following steps:

1) pendimethalin crude product, toluene, dichloroethanes are put into container according to the ratio that mass ratio is 2:1:2.5, then held Sulfuric acid solution is added in device, the acid mass fraction of the phosphoric acid solution is 20%, the matter of the acid solution and pendimethalin crude product Amount is than being 4:5；

3) pendimethalin after refining to first time is further purified, and carries out molecule rectifying, molecule essence using molecule rectifying device The condition evaporated is 110 DEG C of temperature, 0.098 MPa of negative pressure, further converts nitrosamine and becomes pendimethalin, obtains second of purification Pendimethalin afterwards；Through detecting, 98% or more pendimethalin content, content of nitrosamines is below 0.008%；

4) pendimethalin after refining to second recrystallizes, using methanol as solvent, according to the matter of pendimethalin and solvent Amount is stirred 1 hour under the conditions of 65 DEG C of temperature and is dissolved, be added and remove toner and active carbon, mistake than being that the ratio of 1:2 is recrystallized After filter by mother liquor 0.5 hour at a temperature of -5 ~ 5 DEG C, reddish-orange crystals are obtained, centrifugation obtains the diformazan penta after third time refines Spirit, yield 96% further decrease the content of nitrosamine, this final product, the content of nitrosamine is well below 0.001%.

Embodiment 3

The purification process of pendimethalin, comprises the following steps:

1) pendimethalin crude product, toluene, dichloroethanes are put into container according to the ratio that mass ratio is 1:1:2, then in container Middle addition hydrochloric acid solution, the acid mass fraction of the hydrochloric acid solution are 20%, the quality of the acid solution and pendimethalin crude product Than for 9:10；

2) it is stirred 1 hour at a temperature of 70 DEG C, stratification, filtering；Solvent first is removed at a temperature of negative pressure 0.098MPa, 70 DEG C Benzene and dichloroethanes obtain the pendimethalin after refining for the first time；Through detecting, 96% or more pendimethalin content, nitrosamine is dropped to 0.02% or less；

3) pendimethalin after refining to first time is further purified, and carries out molecule rectifying, molecule essence using molecule rectifying device The condition evaporated is 100 DEG C of temperature, 0.098 MPa of negative pressure, further converts nitrosamine and becomes pendimethalin, obtains second of purification Pendimethalin afterwards；Through detecting, 98% or more pendimethalin content, content of nitrosamines is below 0.008%；

4) pendimethalin after refining to second recrystallizes, using methanol as solvent, according to the matter of pendimethalin and solvent Amount is stirred 1 hour under the conditions of 55 DEG C of temperature and is dissolved, be added and remove toner and active carbon, mistake than being that the ratio of 1:2 is recrystallized After filter by mother liquor 0.5 hour at a temperature of -5 ~ 5 DEG C, reddish-orange crystals are obtained, centrifugation obtains the diformazan penta after third time refines Spirit, yield 95% further decrease the content of nitrosamine, this final product, the content of nitrosamine is well below 0.001%.

The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention Within mind and principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.

Claims

1. a kind of purification process of pendimethalin, which is characterized in that comprise the following steps:

1) pendimethalin crude product, toluene, dichloroethanes are put into container according to the ratio that mass ratio is 1~2:1:1.5~2.5 In, then acid solution is added in a reservoir, the acid mass fraction of the acid solution is 10-20%, the acid solution and two The mass ratio of the clever crude product of first penta is 4~5:5；

2) it is stirred 0.5~1 hour at a temperature of 60-100 DEG C, stratification, filtering；Solvent toluene and dichloroethanes are removed, is obtained Pendimethalin after being refined to first time；

2. the purification process of pendimethalin according to claim 1, which is characterized in that acid described in the step 1) is One of phosphoric acid, hydrochloric acid or sulfuric acid.

3. the purification process of pendimethalin according to claim 1, which is characterized in that the work of step 2) the removing solvent Skill condition is negative pressure 0.098-0.01MPa, 65-95 DEG C of temperature.

4. the purification process of pendimethalin according to claim 1, which is characterized in that molecule rectifying in the step 3) Condition is 100-120 DEG C of temperature, negative pressure 0.098MPa.

5. the purification process of pendimethalin according to claim 1, which is characterized in that the recrystallizing technology of the step 4) Are as follows: it uses methanol or ethanol as a solvent, is recrystallized according to the ratio that the mass ratio of pendimethalin and solvent is 1:1.5~2.5, It stirs 0.5-1 hours and dissolves under the conditions of 50-65 DEG C of temperature, be added and remove toner and active carbon, by mother liquor at -5~5 DEG C after filtering At a temperature of stir 0.5~1 hour, obtain reddish-orange crystals.