JPS6055064B2 - Method for producing 1,2,3,4-tetrachlorobenzene-5,6-dithiol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 1,2,3,4-tetrachlorobenzene-5,
The present invention relates to a method for producing 6-dithiol.

More specifically, 1,2,3,4-tetrachloro5,
The present invention relates to a method for obtaining 1,2,3,4-tetrachlorobenzene-5,6-dithiol by heating and reacting 6-dibromobenzene and sodium hydrosulfide. 1
, 2,3,4-tetrachlorobenzene-5,6-dithiol, like other aromatic dithiols, has a strong metal chelating ability and reacts with metal ions to form organometallic complexes. , this complex is known to exhibit a unique absorption spectrum (Monachieft Huia Chemy, vol. 10, pp. 308-320, 1971 and Journal of the American Society, vol. 8).
4870-4875, 196 hours).

Therefore, it is an important compound as a chelating agent for metal ions and a reagent for analyzing metal ions. Also, 1, 2,
3,4-Tetrachlorobenzene-5,6-dithiol has become an important compound as a raw material for the synthesis of useful heterocyclic compounds (U.S. Pat. No. 3,746,707).
issue). 1,2,3,4-tetrachlorobenzene-5,6
- The method for producing dithiol is described in the Journal of the American Society, Volume 8 cited above, which describes a method for producing dithiol using hexachlorobenzene and sodium hydrosulfide in the presence of iron powder and N,N-dimethylformamide as a solvent. te1
A method for obtaining 1,2|3|4-tetrachlorobenzene-5,6-dithiol by reacting at 45°C is described.

According to this method, the yield of 1,2,3,4-tetrachlorobenzene-5,6-dithiol is low and there are many by-products, and the reaction is carried out at temperatures above 145°C in the presence of sodium bisulfide. Since this method requires high temperatures and a long reaction time, expensive materials must be used for the reactor, and it cannot be said to be an industrially advantageous method. Furthermore, when hexachlorobenzene and sodium hydrosulfide are reacted without iron powder, only pentachlorobenzenethiol is obtained, and the desired 1,2,3,4-tetrachlorobenzene-5,6-dithiol is not obtained. (
Industrial Chemistry Magazine Vol. 70 No. 8 (1967) 114-118
page).

In view of this situation, the present inventors have conducted intensive research and have found 1, 2, 3, and 3 that can overcome the above-mentioned drawbacks.
A new method for producing 4-tetrachlorobenzene-5,6-dithiol was discovered and the method of the present invention was completed.
That is, the present invention provides 1,2,3,4-tetrachloro5
, 6-dibromobenzene and sodium hydrosulfide in the presence of a polar organic solvent without or with the addition of iron powder or iron salts 1, 2, 3, 4.
-Tetrachlorobenzene-5,6-dithiol production method. According to the present invention, the yield of 1,2,3,4-tetrachlorobenzene-5,6-dithiol is extremely high compared to when hexachlorobenzene is used as a raw material, and the production of by-products can be extremely reduced. Without,
The reaction can be carried out while keeping the reaction temperature low, and 1,2,3,4-tetrachlorobenzene-5,6-dithiol can be produced in an industrially advantageous method.
When carried out using the method of the present invention, the reaction is milder than when hexachlorobenzene is used as a raw material. 1,2,3,4-tetrachlorobenzene can be obtained at high temperature and in good yield. The reason for this is that when hexachlorobenzene is used, when sodium hydrosulfide reacts with the chlorine atom bonded to the benzene ring, the desired 1, 2, 3, 4
-Tetra. In order to obtain chlorobenzene-5,6-dithiol, it is necessary to react with adjacent chlorine atoms, but this reaction is thought to have a low yield because it is not highly selective. On the other hand, according to the method of the present invention, since 1,2,3,4-tetrachloro-5,6-dibromobenzene is used as a raw material, the bond energy between the carbon of the benzene ring and the bromine atom is Because sodium hydrosulfide reacts more easily with bromine atoms than with chlorine because the bond energy is lower than that between bromine atoms and chlorine atoms, the reaction proceeds at a relatively low temperature, and because bromine atoms are adjacent to each other, they react more easily with bromine atoms. Thiolation adjacent to the molecule tends to proceed with high selectivity. As a result, it is considered that the desired 1,2,3,4-tetrachlorobenzene-5,6-dithiol can be obtained in high yield. Therefore, by the method of the present invention, 1,
Using 2,3,4-tetrachloro-5,6-dibromobenzene as a raw material, 1,2,
It becomes possible to obtain 3,4-tetrachlorobenzene-5,6-dithiol.

Furthermore, the reaction can be carried out in the presence of iron powder or iron salts.

In this case, 1,2,:3,4-tetrachlorobenzene-5,6-dithiol can be obtained in a better yield than when no iron powder or iron salts are added. This is produced by adding iron or iron salts to the 1,
Because 2,3,4-tetrachlorobenzene-5,6-dithiol forms a complex with iron, it can exist more stably during the reaction, so by-product reactions such as disulfide formation reactions between thiol groups are prevented. This is considered to be because the method of the present invention prevents 1,2,3,4-tetrachloro5,6
After adding -dibromobenzene and sodium hydrosulfide to a polar organic solvent, a heating reaction is carried out in the absence or presence of iron powder or iron salts. 1, 2, 3 used in the method of the present invention
, 4-tetrachloro-5,6-dibromobenzene can be easily obtained by reacting 1,2,3,4-tetrachlorobenzene obtained by chlorination of benzene with bromine using a conventional bromination catalyst. Raw materials 1, 2, 3, 4
-The amount of tetrachloro-5,6-dibromobenzene and sodium hydrosulfide used is 2 to 5 mol, preferably 2.5 mol, of sodium hydrosulfide per 1 mol of 1,2,3,4-tetrachloro-5,6-dibromobenzene. The proportion is ~3.0 mol.

Further, as the polar organic solvent used in the method of the present invention, alcohols, amide solvents, dimethyl sulfoxide, and sulforane are used.

Alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, Te
rt-butanol is used. As the amide solvent, dimethylformamide, diethylformamide, dimethylacetamide, N-methylpyrrolidone, tetramethylurea, and hexamethylphosphoramide are used. The amount of the polar organic solvent to be used is 1 to 1 times the weight of 1,2,3,4-tetrachloro-5,6-dibromobenzene, preferably 2 to 5 times by weight. Furthermore, in the method of the present invention,
When carrying out the reaction using iron powder or iron salts, iron powder, divalent or trivalent iron salts, i.e. iron chloride, iron bromide,
Any of iron nitrate, iron sulfate, and iron phosphate may be used.

The amount of these iron powders or iron salts used is 1, 2, 3, 4
The proportion is 0.01 to 2 mol, preferably 0.1 to 1.0 mol, per 1 mol of -tetrachloro-5,6-dibromobenzene.

The reaction temperature is 100-145°C, preferably 110-12
The reaction time at 0° C. varies depending on the reaction solvent, the presence or absence of iron powder, and the reaction temperature, but 8 to 1 hour is usually sufficient.

After the reaction under the above conditions, it is cooled, and if the reaction is carried out without adding iron powder or iron salts, diluted mineral acid is added to the reaction solution to liberate 1,2,3,4-tetrachlorobenzene-5. , 6-dithiol is obtained.

In addition, when iron powder or iron salts are added and reacted, water is added to the reaction solution and the solid obtained is heated with zinc oxide in the presence of an alkali, and then filtered, and a mineral acid is added to the p liquid obtained. By making the mixture strongly acidic, 1,2,3,4-tetrachlorobenzene-5,6-dithiol is liberated. below,
An example is shown.

Note that parts in the examples indicate parts by weight. Example 1 1,2,3 in 100 parts of N,N-dimethylformamide
, 37 parts of 4-tetrachloro-5,6-dibromobenzene (recrystallized from carbon tetrachloride, melting point 250-25rC) and n parts of sodium hydrosulfide (7% weight content) were added, while slowly passing nitrogen gas. After heating to 110°C and reacting for 12 hours, the reaction solution was cooled and poured into 10 CB of ice.
When added to 200 parts of 35% dilute sulfuric acid, pale yellow powder and brown resinous material are liberated.

Only a pale yellow powder was collected by filtration and air-dried to obtain 16 parts of a pale yellow powder (melting point 220-228°C). As a result of gas chromatography analysis, 1,2,3,4-
The content of tetrachlorobenzene-5,6-dithiol was 1% (yield: mol%). Example 2 1,2,3 in 100 parts of N,N-dimethylformamide
,4-tetrachloro-5,6-dibromobenzene 37m
1. Add 3 parts of iron powder, sodium hydrosulfide (7 rut amount % content) seat, and gently pass nitrogen gas, 12 (generations)
After heating to 1 hour and reacting for 1 hour, cool and add 1. After adding an aqueous solution of m dissolved in 120 parts of water, filtration was performed to separate the black solid, which was then air-dried.

Next, this solid was added to 8 parts of methanol together with an aqueous solution of 15 parts of zinc oxide and 30 m of sodium hydroxide dissolved in 300 m of water, and heated for 1 hour at a temperature at which the methanol refluxed. After cooling and filtering, 100 parts of ice was added to the solution.
When poured into 200 parts of 5% dilute sulfuric acid, a pale yellow powder was precipitated. Filter and air dry to give a pale yellow powder (melting point 242
~246°C) was obtained. Analysis by gas chromatography revealed that the content of 1,2,3,4-tetrachlorobenzene-5,6-dithiol was 91% by weight (yield: 71% by mole). Example 3 The same procedure as in Example 2 was repeated except that N,N-dimethylformamide in Example 2 was replaced with sulforan, to obtain a pale yellow powder 23W (melting point 243-24TC).

As a result of analysis by gas chromatography, 1, 2,
The content of 3,4-tetrachlorobenzene-5,6-dithiol was 9% by weight (yield 76% by mole). Example 4 1 (1) part of methanol, 37 parts of 1,2,3,4-tetrachloro-5,6-dibromobenzene, 3 parts of iron powder, and n parts of sodium hydrosulfide (7% content) made of stainless steel. After putting it in an autoclave and replacing it with nitrogen gas,
After reacting at 110°C for 12 hours, the same procedure as in Example 2 was carried out to obtain a pale yellow powder (melting point 225-23).
I got it.

As a result of analysis by gas chromatography, 1, 2,
The content of 3,4-tetrachlorobenzene-5,6-dithiol was 9% by weight. (Yield 62 mol%). Example 5 The same procedure as in Example 2 was repeated except that 3 parts of the iron powder in Example 2 was replaced with 5 parts of ferrous chloride.
42-246°C).

As a result of analysis by gas chromatography, 1, 2,
The content of 3,4-tetrachlorobenzene 5,6-dithiol was % by weight (yield: 72 mol%). Comparative Example 1 The same procedure as in Example 2 was repeated except that 37 parts of 1,2,3,4-tetrachloro-5,6-dibromobenzene in Example 2 was replaced with hexachlorobenzene (2W) to obtain 11 parts of pale yellow powder. .

Claims (1)

[Claims] 1. 1,2,3, characterized in that 1,2,3,4-tetrachloro-5,6-dibromobenzene and sodium hydrosulfide are reacted by heating in the presence of a polar organic solvent. , 4-Tetrachlorobenzene-5,6-dithiol manufacturing method. 2 1,2 characterized by heating and reacting 1,2,3,4-tetrachloro-5,6-dibromobenzene and sodium hydrosulfide in the presence of a polar organic solvent by adding iron powder or iron salts. ,3,4-tetrachlorobenzene-5,6
- A method for producing dithiol.