JPS5949210B2 - Method for producing 2,3-dichloro-1,4-naphthoquinone - Google Patents

Description

Detailed Description of the Invention The present invention relates to 2,3-dichloro-1,4-5 naphthoquinone (hereinafter referred to as , DCNQ).

Conventionally, DCNQ has been produced using 1,4-naphthoquinone (hereinafter abbreviated as NQ) in acetic anhydride using iodine as a catalyst.
A method of chlorinating NQ with chlorine in nitrobenzene using iron powder as a catalyst, and a method of chlorinating NQ with chlorine in nitrobenzene using FeC1336H20 as a catalyst have been known for a long time.

However, iodine is expensive, and when iron or iron chloride is used as a catalyst, the final product contains metal halide impurities. In addition, as a chlorination catalyst for NQ,
Methods using lower N,N-dimethylacylamide, N,N-alkylurea or N-methylpyrrolidone have also been proposed. 20 As a result of our search for a NQ chlorination catalyst that is less toxic, has a high reaction rate, can be recycled, and has a high purity product, we found that phosphoric acid, which was unthinkable with conventional catalysts, Esters are NQ
They found that it is effective as a chlorination catalyst25, and completed the present invention.

The method of the present invention involves chlorinating NQ in an organic solvent that is stable under the reaction conditions in the presence of a catalyst, recycling the mother liquor as needed, adding fresh NQ at the end of the circulation, and adding fresh NQ if necessary. A method for producing 30DCNQ by adding a catalyst, which is characterized in that a trialkyl- or tris(halogenated alkyl)-phosphate ester is used as a catalyst.

In the process of the invention, the trialkyl phosphoric acid 35 esters include, for example, trimethyl, triethyl, tripropyl or tributyl phosphate, as well as, if desired, mixed alkyl phosphates.

In particular, trimethylbosate and triethyl phosphate, which are tri(lower alkyl) phosphates, and among them, triethyl phosphate is the most effective as a catalyst.
As the tris(halogenated alkyl)-phosphate ester, tris(chlorinated lower alkyl) phosphates such as tris(chloroethyl) phosphate, so-called CLP, and tris dichloropropyl phosphate, so-called CRP, are preferred. The phosphoric acid esters specifically illustrated above are easily available industrially and are useful in the method of the present invention. Aryl phosphates such as triphenyl phosphate have significantly lower activity than alkyl phosphates and are not practical. Is the amount of catalyst used 0.5 to 200 weight per NQ? selected from.

When the amount of catalyst is small, the chlorination rate decreases, but the loss of chlorine increases. Further, if the mother liquor is circulated, there is no problem even if the amount of catalyst is further increased. The solvent used in the method of the present invention may be any organic solvent that is stable under the reaction conditions. Examples of inexpensive and industrially available organic solvents include carbon tetrachloride, ethane dichloride, 1,1, 1
-trichloroethane, 1,1,2-trichloroethane,
Trichlorethylene, perchlorethylene, 1,1,2
, 2-tetrachloroethane, monochlorobenzene, dichlorobenzene, trichlorobenzene, halogenated hydrocarbons, nitrobenzene, acetic acid, and the like.

In the method of the present invention, the chlorination of NQ is carried out at a temperature of 10 to 150°C.
It will be held in

The reaction pressure is appropriately selected depending on the type of solvent, reaction temperature, or amount of chlorine supplied, but the reaction is usually carried out under normal pressure. To carry out the method of the present invention, for example, NQ and a catalyst are dissolved in an organic solvent and chlorine is introduced.

that time,. The initial stage of the reaction in which dihydrodichlor NQ is produced from diNQ is carried out at 10 to 40°C, and then the reaction temperature is raised to 50°C or higher to effect dehydrochlorination. It is preferable that the produced monochloro NQ is chlorinated at 50 to 90°C. The reaction solution is cooled, e.g.
The crystals crystallized by cooling to 0° C. are separated, washed with methanol, for example, and dried to obtain highly pure DCNQ.

The concentration of NQ is determined by considering the solubility and operability of NQ and DCNQ in each solvent. The reaction mother liquor contains DCN
Since Q and the phosphoric acid esters as catalysts are dissolved, it is industrially very advantageous to add raw material NQ to the mother liquor and carry out the chlorination reaction, so-called cyclic use. Since phosphoric acid esters are nonvolatile, there is little loss, but it is preferable to replenish them if necessary. Further, the NQ used in the present invention may of course be an industrial NQ.

DCNQ synthesized by the method of the present invention exhibits a golden color, provides a highly pure product, and does not contain metal elements unlike conventional products.

Surprisingly, the mother liquor has little coloration and is a pale yellow-red color, and does not become a dark black mother liquor like when a metal halide is used as a catalyst. Therefore, even if the mother liquor is recycled, the product will not be extremely contaminated, and high-quality DCNQ will be produced.
is obtained as a product. Example 1 Nitrobenzene 50a. NQ (moisture content 5%, dry weight standard purity 96%)
5.259 (4.789 as pure NQ) and triethyl phosphate 19 were added.

After introducing chlorine gas at a flow rate of 100 d/min into the mixed solution at 35° C. for 10 minutes, the flow rate was reduced to 20 TfLt/min to complete chlorination. Gradually raise the liquid temperature until it reaches 9
The temperature was raised to 0°C to stop the reaction. The reaction time is approximately 0.
The time was 5 hours, and the amount of chlorine consumed was about 1.2 times the theoretical amount. The reaction product was cooled to 5° C., and the crystals formed were filtered.

The crystals are washed with a small amount of chlorobenzene and the washings are combined with the mother liquor. Furthermore, it was washed with cold methanol and dried.
The obtained DCNQ is 3f1 and its melting point is 195-
It was 7℃. Add 0 triethyl phosphate to the above mother liquor.
, 89, NQ (purity 96%) 5.29 was added, and the reaction and post-treatment were carried out in the same manner as described above.

The resulting DCNQ is 65f! , melting point is 193-195℃
It was hot. It was carried out 5 times using the same mother liquor circulation method, and the total yield (purity conversion) was 94 moles? It was hot. Similar results were obtained using trichlorobenzene in the above reaction.

Example 2 50 ml of monochlorobenzene, NQ (moisture content 5%, purity on dry basis 96%) was placed in a 200 ml four-bottle flask equipped with a thermometer, stirrer, cooler and chlorine gas inlet tube.
) 5.259, trimethyl phosphate 29 was added.

Add 100ml/min of chlorine gas to the mixed solution at 35°C.
After a minute of introduction, the flow rate was reduced to 20 ml/min to complete the chlorination. The liquid temperature was gradually raised to 90° C. to stop the reaction. The reaction time was about 0.5 hours, and the amount of chlorine consumed was about 1.2 times the theoretical amount. The reaction product is cooled to 5° C. and the crystals that have crystallized are filtered off. The crystals are washed with a small amount of chlorobenzene and the washings are combined with the mother liquor. Furthermore, it was washed with cold methanol and dried. The obtained DCNQ is 3f1 and its melting point is 195-7℃
It was hot. Add 0.6 trimethyl phosphate to the above mother liquor.
9. NQ5.259 of the same quality as above was added, and the reaction and post-treatment were repeated in the same manner as above.

The obtained DCNQ was 649, and the melting point was 193-195°C. It was carried out 5 times using the same method of circulating the mother liquor, and the total yield (purity conversion) was 92 moles? It was hot. Example 3 Using the same equipment as in Example 1, monochlorobenzene 50
d, NQ (moisture content 5%, dry weight standard purity 96%) 15
．． 0f! , tris(2-chloroethyl)phosphate 1
After introducing chlorine gas into the mixed solution at a flow rate of 100 d/min for about 20 minutes at 35 to 440°C, the flow rate was reduced to complete chlorination at about 2.0 a/min.

The liquid temperature was gradually raised to 80° C. to stop the reaction. The amount of chlorine consumed was about 1.25 times the theoretical amount. The reaction product was cooled to 5° C. and the crystals formed were filtered off. The crystals are washed with a small amount of cold methanol and dried.
The obtained DCNQ was 15.39. Its melting point is 1
The temperature was 95-197°C. To the above mother liquor, 0.39% of tris(2-chloroethyl)phosphate and 5.0% of NQl. O
9 and perform the same reaction and post-processing as above, DCNQ
18.59 was obtained.

Claims (1)

[Claims] 1. In an organic solvent stable under reaction conditions in the presence of a catalyst, 1.
Chlorinate 4-naphthoquinone, recycle the mother liquor as necessary, add fresh 1,4-naphthoquinone at the end of the circulation, and add a catalyst if necessary to produce 2,3-naphthoquinone.
- A method for producing 2,3-dichloro-1,4-naphthoquinone, characterized in that a trialkyl- or tris(halogenated alkyl)-phosphate ester is used as a catalyst. Production method. 2. The method according to claim 1, wherein a tri(lower alkyl)- or tris(halogenated lower alkyl)-phosphate ester is used as a catalyst.