JPH01175948A - Production of 3,5-dichlorophenol - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 3,5-dichlorophenol, which is important as an intermediate raw material for pharmaceuticals or agricultural chemicals.

Traditionally, the production method for 3,5-dichlorophenol is as follows:
Much is already known. Examples include:

1) Method of diazotizing 3.5-dichloroaniline and then hydrolyzing it (Journal of Chemical Society)
5ociety) page 2217 (1927). ) 2) Once 1,3,5-trichlorobenzene is converted to 3,5-
A method of converting dichloroanisole into dichloroanisole and then treating it with concentrated hydrochloric acid (Recuei de Travo Simique)
1des Travaux Chimiques)3
See Vol. 7, p. 96 (1917). ) 3) A method in which an alkaline aqueous solution of pentachlorophenol is hydrogenated at high temperature and pressure in the presence of a sulfur compound to partially dechlorinate it (West German Patent 2.44). lower, high temperature;
Hydrogenation at high pressure and partial dechlorination (see European Patent No. 55.198); treatment with hydrogen iodide in the presence of hydrogen iodide and partial dechlorination (see European Patent No. 118.377). However, these known methods are not necessarily advantageous as industrial production methods, as they require multi-stage reactions, have low yields, or use corrosive concentrated hydrochloric acid.

An object of the present invention is to provide an industrially advantageous method for producing 3,5-dichlorophenol from 1-substituted-3,5-dichlorobenzene in two steps. .

The method for producing 3,5-dichlorophenol according to the present invention includes 1-substituted-3,5-dichlorophenol represented by the general formula (I> (wherein, X represents an alkoxy group or a halogen atom). - When producing 3,5-dichlorophenol by heating and reacting dichlorobenzene in the presence of an alkali metal hydroxide and an alcohol, the alkali metal hydroxide is
The reaction is carried out at a temperature range of 170 to 250°C, using 2.5 to 10 moles of alcohol to the compound of formula (I>). It is a feature.

According to the method of the present invention, 3,5-dichlorophenol can be obtained in high yield from 1-substituted-3,5-dichlorobenzene in -steps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the method for producing 3,5-dichlorophenol according to the present invention will be described in detail.

In the compound of formula (I) used as a reaction raw material when producing 3,5-dichlorophenol in the present invention,
X is an alkoxy group or a halogen. Specifically, the alkoxy group is a methoxy group, an ethoxy group, a low-propoxy group, an isopropoxy group, etc., and among these, a methoxy group is particularly preferable, and the halogen atom is a chlorine atom,
A bromine atom or an iodine atom is preferred, with a chlorine atom or a bromine atom being particularly preferred.

Examples of the alkali metal hydroxide used in the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. Among these, sodium hydroxide and potassium hydroxide are particularly preferred.

The amount of alkali metal hydroxide used is 1-substituted-3,
The amount is preferably 2.5 to 10 times, preferably 3 to 8 times, by mole relative to 5-dichlororonzene.

The amount of alkali metal hydroxide used is 1-substituted-3,5-
If it is less than 2.5 times the mole of dichlorobenzene,
This is not preferable because the reaction rate becomes extremely slow and the yield of 3,5-dichlorophenol is extremely reduced.On the other hand, if the amount exceeds 10 moles, 3-chloro-5-alkoxyphenol such as 3-4-5-methoxyphenol This is undesirable because the amount of by-products increases significantly.

Alcohols used in the present invention include methanol,
Ethanol, n-propertool, inpropertool, etc. can be mentioned, among which methanol is particularly preferred. The amount of alcohol used is preferably 2.5 to 10 times the weight of 1-substituted-3,5-dichlorobenzene, preferably 3 to 8 times.
It is twice the weight. The amount of alcohol used is 1-substituted-3,
Even if it is less than 2.5 times the weight of 5-dichlorobenzene, or even if it exceeds 10 times the weight, the reaction rate will be extremely slow and the yield of 3,5-dichlorophenol will be extremely low. This is not preferable because it lowers the temperature.

In the present invention, the reaction can be carried out without using a solvent, but it can also be carried out using an organic solvent that is inert to the reaction. Examples of organic solvents inert to the reaction include aliphatic hydrocarbons such as hexane, heptane, and octane, and aromatic hydrocarbons such as benzene, toluene, xylene, and cumene.

The reaction temperature is 170-250°C, preferably 180-23°C.
It is in the range of about 0°C. Further, the reaction time is arbitrary, but is usually about 0.5 to 20 hours, preferably about 1 to 10 hours.

When carrying out the method of the present invention, the amount of water contained in the raw materials to be charged is preferably 2% by weight or less, preferably 1% by weight or less, particularly preferably 0.2% by weight or less. In addition, when carrying out the above reaction, the water produced by the reaction is either added to the reaction system with a solvent that is azeotropic with water, such as benzene or toluene, and removed from the reaction system by azeotropic distillation, or a dehydrating agent such as sodium sulfate or magnesium sulfate is added. The reaction may be carried out in the presence of both.

After the reaction is complete, to isolate 3,5-dichlorophenol, the reaction mixture is diluted with water and neutralized with an acid such as hydrochloric acid or sulfuric acid. Chlorobenzene may be extracted with an organic solvent that is immiscible with water, and the extracted organic layer may be concentrated to dryness. In addition, if the raw material 1-substituted-3,5-dichlorobenzene remains in the reaction mixture, after diluting the reaction mixture with water, 1-substituted-3,5-dichlorobenzene may be added with an organic solvent that is immiscible with water. - After removing dichlorobenzene by extraction, the aqueous layer may be neutralized with hydrochloric acid, sulfuric acid, etc., and then 3,5-dichlorophenol may be extracted with an organic solvent that is immiscible with water. In this way, 3
, 5-dichlorophenol can be obtained, but in order to obtain even higher purity 3,5-dichlorophenol, ordinary purification means such as recrystallization and distillation may be appropriately employed.

As described above, according to the method of the present invention, 1-substitution-3,
Since 5-dichlorobenzene is reacted under specific conditions in the presence of specific amounts of alkali metal hydroxide and alcohol, 3,5-dichlorophenol can be obtained in high yield in one step.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. Note that the amount of water contained in the raw materials of Examples 1 to 16 shown in the present invention is 0.05 to 0.2% by weight.

1.3.5 in a 50m1 stainless steel autoclave.
- trichlorobenzene 3.6 g (20 mmol), 9
Add 3.4 g (80 mmol) of 5% sodium hydroxide and 18 g (560 mmol) of methanol, seal, and react at 180° C. for 6 hours. After cooling to room temperature, the reaction mixture was poured into 100 ml of water, adjusted to DH4 with a 10% aqueous sulfuric acid solution, and extracted with toluene. After washing the extract with saturated brine, toluene was distilled off under reduced pressure to obtain 2.8 g of 3.5-dichlorophenol (
yield 85%).

The results are shown in Table 1.

Gas chromatography analysis conditions Model: Shimadzu GC-7A Column: 5% 0V-172m glass column (Carrier: Chromosolve W AW DMCS) Temperature: 120°C Detection: FID Carrier gas: Nitrogen 30ml/min Example 1 except that the amount of sodium hydroxide, amount of methanol, temperature, and time were changed as shown in Table 1 in Example 1.
The reaction was carried out in the same manner.

The results are shown in Table 1.

In Example 1, 95% sodium hydroxide was replaced with 8
The reaction was carried out in the same manner as in Example 1 except that 5.3 g (80 mmol) of 5% potassium hydroxide was used.
5-dichlorophenol was obtained with a yield of 75%.

1.3.5-Trichlorobenzene recovery rate 3% In Example 1, 1-bromo-3,5-dichlorobenzene 4.5 g (20
The reaction was carried out in the same manner as in Example 1 except that 3,5-dichlorophenol was used in a yield of 78%.

Recovery rate of 1-bromo-3,5-dichlorobenzene: 0% In Example 1, 3.5% of 1-methoxy-3,5-dichlorobenzene was used instead of 1,3.5-trichlorobenzene.
The reaction was carried out in the same manner as in Example 1, except that the amount of 95% sodium hydroxide was changed to 2.5 g (60 mmol), and 85% of 3,5-dichlorophenol was used. Obtained in yield.

Recovery rate of 1-methoxy-3,5-dichlorobenzene: 1% In Example 1, ethanol 18 was used instead of methanol.
When the reaction was carried out in the same manner as in Example 1, except that g (390 mmol) was used and the reaction temperature was changed to 200°C, 3,5-dichlorophenol was obtained in a yield of 70%.

1.3.5-Trichlorobenzene recovery rate 5% The reaction was carried out in the same manner as in Example 1 except that 3.1 g of toluene was added as a solvent other than methanol. Dichlorophenol was obtained with a yield of 84%.

1.3.5-Trichlorobenzene recovery rate 2% In Example 1, 2.8 g of anhydrous sodium sulfate was used as a dehydrating agent.
The reaction was carried out in the same manner as in Example 1 except that 3,5-dichlorophenol (20 mmol) was added.
Obtained with a yield of 9%.

1.3.5-Trichlorobenzene recovery rate 0% The reaction was carried out in the same manner as in Example 1, except that the amount of sodium hydroxide, amount of methanol, temperature, and time were changed as shown in Table 2. . The results are shown in Table 2. In addition, the amount of water contained in the raw materials shown in the following comparative example is 0.05
~0.2% by weight.

Claims (6)

[Claims] (1) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼... (I) (In the formula, X represents an alkoxy group or a halogen atom.) 1-substituted-3,5- When producing 3,5-dichlorophenol by heating and reacting dichlorobenzene in the presence of an alkali metal hydroxide and an alcohol, the alkali metal hydroxide is converted into the formula (
The reaction is carried out in a temperature range of 170 to 250°C, using 2.5 to 10 times the amount of the compound of formula (I) by mole, and using alcohols of 2.5 to 10 times by weight to the compound of formula (I).
A method for producing 3,5-dichlorophenol, which comprises neutralizing it. (2) 1-substituted-3,5-dichlorobenzene is 1,3,
5-Trichlorobenzene or 1-bromo-3,5-
The method for producing 3,5-dichlorophenol according to claim 1, which is dichlorobenzene. (3) The method for producing 3,5-dichlorophenol according to claim 1, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide. (4) The method for producing 3,5-dichlorophenol according to claim 1, wherein the alcohol is methanol. (5) The method for producing 3,5-dichlorophenol according to claim 1, in which the alkali metal hydroxide is used 3 to 8 times by mole relative to 1-substituted-3,5-dichlorobenzene. (6) The method for producing 3,5-dichlorophenol according to claim 1, in which the alcohol is used in an amount of 3 to 8 times the weight of 1-substituted-3,5-dichlorobenzene.