JP2000297054A - Recovery of chlorinated aromatic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover DCC[di(chlorodimethyl)cyclohexane] and/or TCC[tri(chlorodimethyl)cyclohexane] of chlorinated aromatic compounds from solvents in a convenient operation and to avoid the problem such as the corrosion of an equipment due to the above compounds by changing a chlorinated aromatic compound into an aromatic compound having at least one hydroxyl end group. SOLUTION: This method is to change a compound of the formula C6 H6-n[C(CH3)2Cl]n [wherein, (n) is 2 or 3] into a compound of the formula C6 H6-n[C(CH3)2OH]n. The method is preferably conducted e.g. by the batch wise heat treatment in the presence of a base (e.g. an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide or the like) to precipitate out the compound of the formula C6H6-n[C(CH3)2Cl]n in a state of the compound of the formula C6H6-n[C(CH3)2OH]n and then by recovering it through solid- liquid separation. The compound of the formula C6H6-n[C(CH3)2Cl]n preferably exists in a solvent (preferably aromatic hydrocarbons or aliphatic hydrocarbons).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for recovering chlorinated aromatic compounds.

[0002]

2. Description of the Related Art A chlorinated aromatic compound represented by the general formula 1: C ₆ H _6-n [C (CH ₃ ) ₂ Cl] _n (1) wherein n is 2 or 3. (Hereinafter, DCC for n = 2 and TCC for n = 3) are used as polymerization initiators when producing cationically polymerizable monomers such as polyisobutylene. Particularly, it is a polymerization initiator capable of synthesizing a polymer having a small molecular weight distribution by living cationic polymerization under appropriate reaction conditions, and is a very useful substance.
However, DCC and TCC are inherently unstable substances, and when left at room temperature or heated for a short time, easily cause a reaction such as decomposition or condensation, and generate hydrogen chloride. When a solvent containing these substances is supplied to a recovery facility such as a distillation column for recycling, it causes corrosion of the facility. In the case of incineration treatment without recycling, there is a problem of generation of dioxins in addition to the problem of equipment corrosion, and it is necessary to control the incineration temperature. Both recycling and non-recycling are disadvantages of industrial equipment design, including cost issues. The present inventors have tried to actually recycle a solvent containing DCC, and have studied.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for recovering DCC and TCC, which are chlorinated aromatic compounds, from a solvent by a simple operation and avoiding problems such as equipment corrosion caused by the compounds. Is to do.

[0004]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that, by heating in the presence of a solvent in the presence of an alkali to neutralize hydrogen chloride generated from DCC and TCC, the compound is generally removed. The present inventors have found that the compound can be recovered by precipitating it as a hydroxyl-terminated compound represented by the formula 2 and then performing solid-liquid separation, thereby completing the present invention.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As the base used in the present invention, conventionally known bases can be used without any particular limitation.
Basic organic compounds such as methylpyridine and trimethylamine, sodium methoxide, sodium ethoxide, metal alkoxides such as potassium methoxide and potassium t-butoxide, metal salts of carboxylic acids such as sodium acetate and potassium acetate, sodium hydroxide, Metal hydroxides such as potassium hydroxide, calcium hydroxide and lithium hydroxide; metal hydrides such as sodium hydride and calcium hydride; and the like.

The base of the present invention can be used in the form of an aqueous solution (ie, a basic aqueous solution). For example, metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide and lithium hydroxide can be used. Is preferably used as an aqueous solution. Among these,
An aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is preferred. When the base of the present invention is a metal alkoxide, it is preferably used as an alcohol solution.

The present invention relates to a compound represented by the general formula 1
In recovering the compound represented by the formula, the compound is precipitated as a compound represented by the general formula 2, and recovered by solid-liquid separation. Among them, a preferable method is to perform a heat treatment by a batch method in the presence of a base, General formula 1
Is precipitated as a compound represented by the general formula 2 and recovered by solid-liquid separation. As the most preferable method, a compound represented by the general formula 1 is mixed with an aqueous solution of sodium hydroxide or potassium hydroxide, heated and stirred by a batch method to precipitate the compound represented by the general formula 2, and recovered by solid-liquid separation. Method. In this case, a conventionally known method such as filtration and centrifugation can be used without particular limitation as a method for solid-liquid separation of the precipitated compound represented by the general formula 2; The filtration method is effective. The compound represented by the general formula 2 recovered by solid-liquid separation is reacted by reacting gaseous hydrogen chloride in a solution under ice-cooling (JP Kennedy et al., Polym. Bull
l. (Berlin), 4 (9), 513- (198
1)), a method in which a reaction is carried out by contacting with hydrochloric acid in the presence or absence of an organic solvent (Japanese Patent Laid-Open No. 8-2)
No. 91090) or a method of reacting with an organic acid chloride (JP-A-10-251174), etc., to easily obtain the original chlorinated aromatic compounds DCC and TCC. The present invention also provides a new process for obtaining DCC and TCC. Further, for example, when DCC and TCC are synthesized in a low yield, the present invention is an effective method for a kind of purification such as recovery of DCC and TCC from the reaction solution.

The solvent used in the present invention includes aromatic hydrocarbons such as benzene, toluene, xylene and styrene, halogenated aromatic hydrocarbons such as chlorobenzene, propane, butane, butene, pentane, pentene, pentadiene, hexane, hexene and the like. It refers to those containing all or a part of aliphatic hydrocarbons such as hexadiene, heptane, octane, cyclohexane, methylcyclohexane, and ethylcyclohexane, and halogenated hydrocarbons such as dichloromethane, dichloropropane, and butyl chloride.

In the present invention, the temperature during the heat treatment is usually 0 to 250 ° C., preferably 10 to 180 ° C.
And more preferably 20 to 150 ° C. When an aqueous alkali solution such as an aqueous sodium hydroxide solution or aqueous potassium hydroxide solution is used as the base, the reaction is accelerated by adding an amphoteric solvent such as acetone or methanol. Since the compound to be dissolved is dissolved, its addition amount is preferably set to 10% by volume or less. The amount of alkali added into the system is 1 to the amount (mol) of chlorine contained in DCC and TCC contained in the solvent.
It is sufficient to add twice the amount (mol), but if the content is unknown, it is necessary to add an excess amount.

[0010]

The present invention will be specifically described below with reference to examples. However, the present invention is not limited by these examples.

(Example 1) 200 g of hexane (including DCC and its by-product, chlorobenzene) used for crystallization of DCC was placed in a pressure-resistant container having an internal volume of 500 ml.
90 g of a 0% aqueous sodium hydroxide solution was charged, heated to 100 ° C. in a closed state, and stirred and mixed for 4 hours. Thereafter, the mixture was once cooled, and the whole amount was transferred to a 500 ml distillation can container, and distilled in a glass packed tower having an inner diameter of 20 mm, a height of 1400 mm and a theoretical plate number of 10 to recover hexane. When the recovered hexane was analyzed by gas chromatography,
No impurities were found. The pH of the azeotropically recovered water
Was examined with a pH test paper and found to be neutral, indicating that no hydrogen chloride gas was generated. After distillation,
The liquid in the distillation still was filtered, and the obtained solid was analyzed by NMR and IR.
As a result, it was confirmed that the compound represented by the general formula 2 (where n = 2) was obtained.

[0012]

According to the present invention, by heating a solvent containing a chlorinated aromatic compound, DCC and TCC, together with an alkali, the compound is precipitated as a compound represented by the general formula (2). The compound can be recovered by solid-liquid separation. According to the present invention, D
Since the problem of corrosion of equipment due to hydrogen chloride generated by decomposition of CC and TCC and the problem of generation of dioxins during incineration can be avoided, the recovered compounds can be easily converted to DCC and TCC. And an efficient collection system can be assembled.

Claims (5)

[Claims] 1. A compound represented by the general formula 1: C ₆ H _6-n [C (CH ₃ ) ₂ Cl] _n (1) wherein n is 2 or 3 2: a compound represented by the formula: C ₆ H _6-n [C (CH ₃ ) ₂ OH] _n (2), wherein n is 2 or 3. A method for recovering the represented compound. 2. The method according to claim 1, wherein the compound represented by the general formula 1 is heated in the presence of a base to give the compound represented by the general formula 2. 3. The method according to claim 1, wherein the compound represented by the general formula 1 is present in a solvent that is an aromatic hydrocarbon or an aliphatic hydrocarbon. 4. The method according to claim 2, wherein an aqueous solution of sodium hydroxide and / or potassium hydroxide is used as the base. 5. A method for purifying a compound represented by the general formula 1 using the method according to claim 1.