CN109134188A

CN109134188A - A method of preparing 2,6- dichlorotoleune

Info

Publication number: CN109134188A
Application number: CN201811022664.2A
Authority: CN
Inventors: 杨勇; 刘林佳; 薛宝安
Original assignee: JIANGSU BEYOND CHEMICALS CO Ltd
Current assignee: JIANGSU BEYOND CHEMICALS CO Ltd
Priority date: 2018-09-04
Filing date: 2018-09-04
Publication date: 2019-01-04

Abstract

The invention discloses a kind of methods for preparing 2,6-DCT, and in the method, 2,3- dichlorotoleune and chlorine reaction obtain 2,3- dichloromethane phenyl ring chlorizate；Using hydrogen as reducing agent, load type palladium catalyst is catalyzed reductase 12, and 3- dichloromethane phenyl ring chlorizate obtains 2,6- dichlorotoleune, the by-product reacted repeat chlorination, catalytic reduction reaction, make 2,3- dichlorotoleune is converted into the gross production rate of 2,6-DCT up to 30% or more；2,6-DCT generates new economic value as important chemical industry intermediate.

Description

A method of preparing 2,6- dichlorotoleune

Technical field

The present invention relates to a kind of methods for preparing 2,6-DCT, prepare 2 more particularly to one kind 2,3- dichlorotoleune, The method of 6- dichlorotoleune.

Background technique

2,3- dichlorotoleune are the side reaction products that part industrial production chlorotoluene obtains, and utility value is not high, at present It is used mostly as solvent, causes great waste.2,3- dichlorotoleune is further processed, rate is utilized Height, good in economic efficiency product, such as 2,6-DCT not only contribute to the effective use of resource, and can be realized considerable Economic benefit.

2,6-DCT is a kind of important fine chemical material, can be widely used in manufacture fungicide, insecticide, weeding Agent, dyestuff and pigment, medicine and other chemical products, status and effect have been to be concerned by more and more people, be applied to medicine, Pesticide and dye industry etc..Using 2,6-DCT as reaction intermediate, 2,6- dichlorobenzaldehyde, 2,6- dichloro can be derived Benzonitrile, 2,6- dichlorobenzoic acid, 2,6- difluorobenzamide, 2,6- difluorobenzonitrile, 2,6- difluoroaniline, 2,6- dichloro-benzenes Amine and 2,6-DCT are the compounds such as diclofenac penicillin, have important application value at many aspects.

The Traditional Industrialization production line of 2,6-DCT is mainly diazotising method, firstly generates 2,6- dinitrobenzene, Further reaction generates 2,6-DCT, and the process costs are high, and there is pollution weight, and exhaust gas, waste water are more intractable, by The product competitiveness in the market of method production is low；Currently, carrying out chlorination in the presence of a catalyst generally using p-chlorotoluene as raw material Reaction, reaction product are separated by rectifying column, obtain 2,6-DCT, but this method inevitably produces greatly How the by-product for measuring the phenyl ring chlorination of 2,3- dichloromethane, continue with this product, play its economic value, become people urgently Problem to be solved.

Summary of the invention

The side reaction product 2,3 dichloro toluene waste obtained for above-mentioned industrial production chlorotoluene and production 2,6- bis- The high problem of chlorotoluene process costs, it is that raw material prepares 2,6-DCT that the present invention provides one kind with 2,3- dichlorotoleune Method.

" more chlorotoluenes " of the present invention refers to containing chlorotoluene compounds more than three chlorine.

A method of 2,6-DCT is prepared, is included the following steps:

1. the synthesis of load type palladium catalyst: carrier impregnation adsorbs palladium source aqueous solution, dry in 100 ~ 120 DEG C after natural drying It is dry.

Preferably, the carrier in load type palladium catalyst is silicon carbide, and specific surface area is greater than 100 m²/ g, diameter 2 ~ 4 Mm, negative palladium rate is 0.1 ~ 5% after load.

Preferably, load type palladium catalyst load palladium source aqueous solution used is 5% tetramminepalladous chloride aqueous solution.

2. chlorination reaction: 2,3 dichloro toluene and chlorine reaction obtain 2,3 dichloro toluene ring chlorizate.

3. catalytic reduction reaction: load type palladium catalyst being added in the reactor, is passed through hydrogen evacuation of air, keeps hydrogen Atmosphere is enclosed, and is passed through 2,3- dichloromethane phenyl ring chlorizate and is carried out catalytic reduction reaction, reaction product through rectifying column isolated 2, 6- dichlorotoleune.

Wherein, reaction pressure is 0.01 ~ 0.10 MPa, and reaction temperature is 150 ~ 250 DEG C；Catalytic reduction reaction is The molar ratio of continuous fixed bed reaction or continuous, feed hydrogen and 2,3- dichloromethane phenyl ring chlorizate is 0.2 ~ 2:1, and mass space velocity is 0.3 ~ 1.5 h^-1。

The utility model has the advantages that

1. load type palladium catalyst long service life used in the present invention, effective catalysis time is greater than 1000 h.

2. the present invention is prepared using the side reaction product 2,3 dichloro toluene that industrial production chlorotoluene obtains as reaction raw materials 2,6-DCT, the other by-products reacted may be repeated chlorination, catalytic reduction reaction, so that 2,3- dichlorotoleune The gross production rate of 2,6-DCT is converted into up to 30% or more, and product 2,6-DCT is as important chemical industry Intermediate generates new economic value.

Specific embodiment

The present invention is described in further detail below with reference to embodiment, but embodiments of the present invention are not limited to This, while its shown data does not represent the limitation to feature of present invention range.

Embodiment 1

1. 25 g silicon carbide cylindrical particles, dipping absorption 10 mL containing 5% tetramminepalladous chloride aqueous solution, after natural drying in 110 DEG C after dry 5 hours load type palladium catalyst.

2. 2,3 dichloro toluene and chlorine reaction obtain 2,3 dichloro toluene ring chlorizate.

3. filling 25 g load type palladium catalysts in 20 mm cylindrical reactor of diameter, 150 DEG C are warming up to, leads to hydrogen Atmosphere of hydrogen is kept after one hour；Reaction pressure is 0.05 MPa, is continuously added to 2,3- dichloromethane phenyl ring chlorizate, and quality is empty Speed is 0.9 h^-1, sampled after reacting 1h, with gas chromatographic analysis, each composition quality content such as 1 institute of table in catalytic reduction reaction front and back Show；Reaction product the 2,6- dichlorotoleune and other by-product isolated through rectifying column.

Each composition quality content before and after catalytic reduction reaction in 1 embodiment 1 of table

Serial number	Title	Before reaction (%)	After reaction (%)
				1	Toluene	/	2.85
2	Monochlorotoluene isomer mixture	/	9.91
				3	2,5-/2,4-/3,4- dichlorotoleune	/	7.19
4	2,6- dichlorotoleune	/	9.92
				5	More chlorotoluenes	86.21	48.85
6	2,3 dichloro toluene	13.78	18.98

4. other by-products obtained in step 3 are repeated step 2 and 3, finally isolate to obtain 2,6-DCT 13.2 mL, purity 99.9%, total conversion ratio are 36%.

Embodiment 2

1. 25 g active carbon cylindrical particles, dipping absorption 10 mL containing 5% tetramminepalladous chloride aqueous solution, after natural drying in 110 DEG C after dry 5 hours load type palladium catalyst.

3. filling 25 g load type palladium catalysts in 20 mm cylindrical reactor of diameter, 200 DEG C are warming up to, leads to hydrogen Atmosphere of hydrogen is kept after one hour；Reaction pressure is 0.02 MPa, is continuously added to 2,3- dichloromethane phenyl ring chlorizate, and quality is empty Speed is 0.3 h^-1, sampled after reacting 1h, with gas chromatographic analysis, each composition quality content such as 2 institute of table in catalytic reduction reaction front and back Show；Reaction product the 2,6- dichlorotoleune and other by-product isolated through rectifying column.

Each composition quality content before and after catalytic reduction reaction in 2 embodiment 2 of table

Serial number	Title	Before reaction (%)	After reaction (%)
				1	Toluene	/	1.77
2	Monochlorotoluene isomer mixture	/	6.88
				3	2,5-/2,4-/3,4- dichlorotoleune	/	5.64
4	2,6- dichlorotoleune	/	7.45
				5	More chlorotoluenes	86.21	53.94
6	2,3 dichloro toluene	13.78	21.49

4. other by-products obtained in step 3 are repeated step 2 and 3, finally isolate to obtain 2,6-DCT 3.8 mL, purity 99.9%, total conversion ratio are 31 %.

Embodiment 3

3. filling 25 g load type palladium catalysts in 20 mm cylindrical reactor of diameter, 250 DEG C are warming up to, leads to hydrogen Atmosphere of hydrogen is kept after one hour；Reaction pressure is 0.1 MPa, is continuously added to 2,3- dichloromethane phenyl ring chlorizate, and quality is empty Speed is 1.5 h^-1, sampled after reacting 240 h or 480 h, with gas chromatographic analysis, each composition quality in catalytic reduction reaction front and back contains Amount is as shown in table 3.Reaction product the 2,6- dichlorotoleune and other by-product isolated through rectifying column.

Each composition quality content before and after catalytic reduction reaction in 3 embodiment 3 of table

Serial number	Title	Before reaction (%)	It reacts (%) after 240 h	It reacts (%) after 480 h
					1	Toluene	/	2.90	2.80
2	Monochlorotoluene isomer mixture	/	10.01	9.95
					3	2,5-/2,4-/3,4- dichlorotoleune	/	7.29	8.00
4	2,6- dichlorotoleune	/	9.88	9.76
					5	More chlorotoluenes	86.21	47.92	47.91
6	2,3 dichloro toluene	13.78	21.87	21.53

4. other by-products obtained in step 3 are repeated step 2 and 3 when the reaction time is 240 h finally to isolate 21.9 mL of 2,6-DCT is obtained, purity is 99.9 %, and total conversion ratio is 36 %；When reaction time is 480 h, finally It isolates to obtain 21.1 mL of 2,6-DCT, purity is 99.9 %, and total conversion ratio is 35 %.

Claims

1. a kind of method for preparing 2,6-DCT, which comprises the following steps:

(1) 2,3 dichloro toluene and chlorine reaction obtain 2,3 dichloro toluene ring chlorizate；

(2) load type palladium catalyst is added in the reactor, is passed through hydrogen evacuation of air, keeps atmosphere of hydrogen, 2,3- bis- is added Chloromethane phenyl ring chlorizate carries out catalytic reduction reaction, and reaction product is through the isolated 2,6-DCT of rectifying column.

2. the method according to claim 1 for preparing 2,6-DCT, which is characterized in that born described in step (2) The carrier of load type palladium catalyst is silicon carbide, and specific surface area is greater than 100 m²/ g, 2 ~ 4 mm of diameter；Negative palladium rate is after load 0.1 ~ 5 wt%。

3. the method according to claim 2 for preparing 2,6-DCT, which is characterized in that load type palladium catalyst passes through Following methods preparation: carrier impregnation adsorbs palladium source aqueous solution, after natural drying in 100 ~ 120 DEG C of dryings.

4. the method according to claim 3 for preparing 2,6-DCT, which is characterized in that the palladium source aqueous solution is 5% tetramminepalladous chloride aqueous solution.

5. the method according to claim 1 for preparing 2,6-DCT, which is characterized in that the hydrogen and 2,3- bis- The molar ratio of chloromethane phenyl ring chlorizate is 0.2 ~ 2:1.

6. the method according to claim 5 for preparing 2,6-DCT, which is characterized in that catalysis reduction in step (2) Reaction is continuous fixed bed reaction or continuous, and mass space velocity is 0.3 ~ 1.5 h^-1。

7. the method according to claim 6 for preparing 2,6-DCT, which is characterized in that catalysis reduction in step (2) Reaction pressure is 0.01 ~ 0.10MPa, temperature is 150 ~ 250 DEG C.

8. the method according to claim 1 for preparing 2,6-DCT, which is characterized in that 2,3- dichloro in step (1) Toluene ring chlorizate includes more chlorotoluenes and 2,3 dichloro toluene.