JPS6226238A - Method of dimerizing aromatic halogen compound - Google Patents

Abstract

PURPOSE:To obtain in high yield the tilted compound, by dehalogenating and dimerizing an aromatic compound containing at least one halogen nucleus in the presence of a palladium catalyst, water and a polyhydric alcohol and/or formaldehyde. CONSTITUTION:An aromatic compound (e.g., chlorobenzene, etc.,) containing at least one halogen atom at an aromatic nucleus carbon is dehalogenated and dimerized in the presence of a palladium catalyst (especially palladium- active carbon catalyst is preferable and amount of it used is preferably 30-0.1mg atom calculated as Pd atom based on 1mol aromatic halogen compound), water and a polyhydric alcohol (e.g., ethylene glycol, glycerin, etc.) and/or a formaldehyde (e.g., paraformaldehyde, formalin, to give a dimer of the aromatic compound. Preferably a halogen acceptor (e.g., NaOH, etc.,) is also used in the reaction. USE:A raw material for heat-resistant polyimide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a dimer of an aromatic compound with high yield by dehalogenating and dimerizing an aromatic halogen compound.

[Prior art]

Dimers of aromatic compounds are useful as various industrial raw materials), for example, , 7, #, 3', group'
-Biphenyltetracarboxylic acid alkali metal salts are very useful as raw materials for heat-resistant polyimide resins.

Conventionally, as a method for producing a biphenyl compound by dehalogenating and dimerizing an aromatic halogen compound, for example, a catalyst supporting metal palladium (
Dehalogenation dimerization method in the presence of pd-supported catalyst) and methanol, (J, Am, Ohem, S
oa, ? /ri76 (19!Iri), Tokko Akira! Day 1l
Ioiz) or a method of dimerization using palladium supported on activated carbon, sodium carbonate and a methanol solvent or a dioxane-ethylene glycol mixed solvent, (
Bull, SoC, Ohlm, Fy', 279/ (
/ Deku 3)) is known.

However, these known methods have the disadvantage that the yield of the biphenyl compound is low, and in some cases, a large amount of dehalogenated aromatic compound monomer is produced as a by-product, resulting in low selectivity for the desired biphenyl compound.

[Problem that the invention seeks to solve]

The present inventors have conducted intensive research on a method for producing biphenyl compounds in high yield and with good selectivity by removing aromatic and rogen compounds. The present invention has been completed by discovering that biphenyl compounds can be produced in high yield and with good selectivity by reacting in the presence of formaldehydes or formaldehydes.

[Means to solve all problems]

The gist of the present invention is to dehalogenate and dimerize an aromatic compound having at least 7 halogen atoms on the aromatic carbon in the presence of a palladium catalyst, water, and a polyhydric alcohol and/or formaldehyde. It consists in a method for dehalogenating and dimerizing halogenated compounds.

The present invention will be explained in detail below.

Aromatic compounds having at least 7 halogen atoms on the aromatic carbon are used as starting materials in the process of the invention. Examples of the at least seven halogen atoms in the aromatic carbon include iodine, bromine and chlorine, preferably bromine and chlorine, and it is particularly suitable to use inexpensive chlorine atoms. When there are 2 or more halogen atoms substituted in the aromatic nucleus of an aromatic compound, the halogens may be the same or different, and the number of halogen atoms may be up to 6. If the number of halogen atoms is large, dimerization may occur. Although dehalogenation occurs at the same time, the number of halogen atoms is preferably 3 or less. If the core carbon of the aromatic compound is adjacent to an atom having a substituent other than the at least seven halogen atoms, the yield of the biphenyl compound may decrease.

Specific examples of the aromatic halogen compounds used in the method of the present invention include chlorobenzea, p-chlorobromobenzene, p-chlorodiphenyl, p-chlorophenol, p-chloroanisole, p-chlorobenzami).
', p-chloroaniline, p-chloronitrobenzene,
Lithium of p-chlorobenzophenone, p-chloroacetophenone, p-chlorobenzenesulfonic acid sodium salt, p-chlorobenzoic acid, p-chlorobenzonitrile, β-chloronaphthalene, a-chloroornexylene, y-chloroorthophthalic acid , alkali metal hydrochloric anhydrides such as sodium and potassium, and tt, S-)chlorophthalic acid.

Palladium catalysts used in the present invention include inorganic acid palladium salts such as palladium chloride and palladium nitrate, organic acid palladium salts such as palladium acetate and palladium phthalate, palladium chelate salts containing β-diketones such as acetylacetone, and metal palladium. Can be mentioned. Among these, those in which metallic palladium is supported on carriers such as activated carbon, silica, alumina, silica alumina, titanium oxide, magnesia, diatomaceous earth, graphite, barium carbonate, calcium carbonate, and zeolite are preferred, and palladium is particularly preferred.
Activated carbon catalysts are preferred. The metal palladium supported on these palladium-carrier catalysts is palladium-carrier Vc
0.7 to -0% by weight, especially. , it is preferable that about 70 weight X is supported on the left.

The amount of the palladium catalyst to be used is /θ0-0.007 milligram atom in terms of palladium atom, preferably JO-0,/milligram atom, per mol of the aromatic halogen compound.

In the method of the present invention, it is important that water, polyhydric alcohol and/or formaldehyde be present in the reaction thread consisting of the aromatic halogen compound and palladium catalyst.

When the aromatic halogen compound is water-soluble,
It can be used as an aqueous solution or directly added to the reaction system. The amount of water used is at least 0% relative to the aromatic halogen compound, palladium catalyst, polyhydric alcohol and/or formaldehyde and optionally the halogen acceptor (described below) and the reaction medium containing the solvent.
．． /volume%, preferably 1 volume% or more. When the aromatic halogen compound is water-soluble, it is preferable to use a solvent amount. On the other hand, in the case of a water-soluble compound, the use of a large amount of water may actually reduce the yield of the biphenyl compound, so the amount of water used is preferably selected from the range of 1 to 60% by volume.

If the amount of water used is less than the above range or if water is not added, the yield and selectivity of the biphenyl compound will decrease, which is not preferable.

The polyhydric alcohols used in the present invention include ethylene glycol, phlopylene gellicol, cohydric alcohols such as /, -1butanediol, /13-propanediol, /, 177'tanediol, and trihydric alcohols such as chrycerin. , pentaeryth IJ)-ol and the like. Covalent or trihydric alcohols such as temoethylene glycol, propylene glycol, /, --butanediol, glycerin, etc. are preferred. The amount of polyhydric alcohol used is 0 per mole of aromatic compound.
．． 0/~! ;0 mol, preferably o, r-i.

It is a mole.

Outside the above range, the yield of biphenyl compounds decreases, which is not preferable. As for how to use these polyhydric alcohols, a predetermined amount within the above range may be added at once, or they may be supplied continuously or intermittently during the dehalogen dimerization reaction.

Preferred formaldehydes used in the present invention are paraformaldehyde and commercially available 3S% formalin.

The amount of formaldehyde used is 0.07 to 30 mol, preferably Q, 5 to 10 mol, per 1 mol of the aromatic halogen compound on a monomer basis.

In the method of the present invention, it is preferable to use a halogen receptor in combination. The halogen acceptor may be any substance that can accept the halogen atom generated during the dehalogenation di-fuming reaction.
Usually organic and inorganic bases.

Examples of the organic base include tertiary amines such as triethylamine, tributylamine, and trioctylamine, and examples of the inorganic base include alkali metal compounds and alkaline earth metal compounds. Among these, alkali metal compounds are preferred; specifically, alkali metals include inorganic acid salts such as carbonic acid, phosphoric acid, and boric acid, organic acid salts such as hydroxides, acetic acid, and phthalic acid, and alkoxides. Can be mentioned.

Particularly preferred examples include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium methoxide, potassium tert-butyrate, and the like.

The amount of these halogen acceptors to be used varies depending on the number of halogen atoms contained in the aromatic halogen compound as a starting material and the presence of other arbitrary substituents such as carboxyl groups, but usually the aromatic halogen compound 1 0.0 per mole.
0/~io.

mol, preferably /-10 mol is used.

If the amount used is outside the above range, the retention of the biphenyl compound will be reduced, which is undesirable.

The method of the present invention can be carried out either in the presence or absence of a solvent, but when a solvent is used, it is carried out in the presence of a solvent that is inert to the reaction.

Examples of such solvents include ether compounds such as tetrahydrofuran and dioxane, acetone, diethyuketo 7, mef, and ekayagato 7. Keto, □ compounds, ester compounds such as ethylene glycol diacetate, water, etc.

The amount of such a solvent to be used is not particularly limited, but is usually o, oi to
It is selected from a range of 10θ parts.

In the method of the present invention, a mixture consisting of the aromatic halogen compound, palladium catalyst, water, and polyhydric alcohol and/or formaldehyde is mixed at 3θ° C., preferably in the absence or presence of a solvent. rO-,20
This is done by heating to 0°C.

The reaction pressure is from normal pressure to 0kg/cA, preferably from normal pressure to /
00 kg/cd and, if necessary, in the presence of an inert gas. The reaction time is not particularly limited and is appropriately selected depending on the raw materials, amount of catalyst, reaction temperature, pressure, etc., but is usually about 70 minutes to 1 hour.

The method of the present invention can be carried out batchwise, semi-batchwise or continuously.

After the reaction, the palladium catalyst used in the reaction is separated from the reaction solution by a commonly used method such as extraction, crystallization, or reduction.

When the palladium-supported catalyst is used, it can be easily separated and recovered by filtration and used again in the deno-rogenization reaction.

The biphenyl compound obtained in the present invention is separated and obtained from the reaction solution by evaporation, distillation, crystallization method, acid precipitation method, etc. according to its physical properties.

〔Effect of the invention〕

According to the method of the present invention, biphenyl compounds can be obtained in high yield and with good selectivity by mixing a small amount of polyhydric alcohol and/or formaldehyde @total presence in the reaction thread, making it an extremely useful method industrially. It is.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention.

Example 1. Hastelloy spinner stirring type with internal volume of 70-! -4'-chlorophthalic anhydride (hereinafter referred to as gu-OPA) is added to distilled water.
) i, g A i (phthalic anhydride o, i!! and dichlorophthalic anhydride o, o as impurities)
IIg was contaminated. ) and sodium hydroxide diy completely dissolved therein and a predetermined amount of ethylene glycol were charged, the autoclave was sealed, and the reaction was carried out at a temperature of 60° C. for JO minutes. When analyzed by reaction liquid chromatography, it was found that the reaction solution contained deno-logogenated orthophthalic acid sodium salt (hereinafter abbreviated as FA salt) and the desired J, 4t, J', 'I'- and 2-phenyltetracarboxylic acid sodium salt (hereinafter abbreviated as S-BTO salt) was produced. The results are shown in Table-/.

Comparative Example/, λ, 3 The same procedure as Example 7 was carried out except that a predetermined amount of methanol was used instead of ethylene glycol. The results are shown in Table-/.

Table -/Example 3 Instead of ethylene glycol/, -monobutanediol! It) It was carried out in the same manner as in Example except that MiIJmol was used. 4I-OPA conversion rate lI9%, 13-BTO salt yield 26. %, and the B-BTO salt selectivity was tada%.

Example Glycerin eOmiIJ instead of daethylene glycol
The reaction was carried out in the same manner as in Example 1, except that the reaction was carried out at 100° C. for 1 hour and 30 minutes.

OPA conversion rate lθO%, 5-BTO salt yield (7,
,7%.

The procedure was the same as in Example G, except that paraformaldehyde was used instead of glycerin.

It was 100% OPA conversion and 3t% 5-BTO.

Example 6 Chlorobenzene, 3. ,)7
79. r wt % palladium on carbon 〇6y1 Sodium carbonate J, / r i , ethylene glycol 10ml
, 10 mt of distilled water and 70 mt of dioxane were added.
The reaction was carried out at 0°C for 5 hours.

The conversion of chlorobenzene was 5Abg, 4%, the yield of biphenyl was XjJ%, and the selectivity of biphenyl was 7A'X.

Comparative Example 6 The same procedure as Example 6 was carried out except that 20 ml of dioxane was used instead of distilled water.

Conversion rate of chlorobenzene? The yield was 4t, f%, the biphenyl collection rate was 1%, and the biphenyl selectivity was 1%.

Example The same procedure as in Example 6 was carried out, except that dichloroorthoxylene, Co/91, was used instead of dichlorobenzene.

Conversion IK of darkchloroortho-xylene*9.6%, 3,
＆ 、 、? The yield of F'-tetramethylbiphenyl was 2.5%.

Claims (1)

[Claims] (1) An aromatic halogen compound characterized by dehalogenating and dimerizing an aromatic compound having at least one halogen atom in the aromatic carbon in the presence of a palladium catalyst, water, a polyhydric alcohol, and/or formaldehyde. Dehalogenation dimerization method.