JPH06199871A - Production of triarylboron - Google Patents

Abstract

PURPOSE:To obtain a method for stably producing a high-purity triarylboron in high yield. CONSTITUTION:A boron halide at 0.1-8.0mol/L concentration is made to react with an arylmagnesium halide at 0.1-3.0mol/L concentration in an organic solvent. In the process, the arylmagnesium halide in an amount of 3.1-3.5mol based on 1mol boron halide is made to react therewith and an ethereal solvent is then removed from the reactional system to solidify a magnesium halide salt formed as a by-product. Thereby, the objective triarylboron taken in the magnesium salt is liberated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing triarylboron. More specifically, by limiting the molar ratio of boron halide to arylmagnesium halide, highly pure triarylboron is stably produced in high yield.

[0002]

It is already known that alkyl and aryl boron compounds can be obtained by reacting an organomagnesium reactant with a boron halide such as boron trifluoride ethyl ether complex. (For example, Inorg. Synth., 1
5, 1947, P134) However, when the arylmagnesium halide and the boron halide are reacted in excess of the arylmagnesium halide even if the molar ratio is slightly smaller than 3: 1, or when the dropping time of the arylmagnesium halide is short, It is stated that the production of tetraaryl borate ion becomes remarkable and the yield of triaryl boron is reduced, and the manufacturing conditions become strict and the management of the manufacturing process becomes difficult.

Another method for producing triarylboron is to use ultrasonic waves after adding phenyl bromide to metal magnesium and boron trifluoride ethyl ether complex (for example, J. Org. Chem., 51, 1986, P
427) or a method for synthesizing triarylboron from phenylmagnesium bromide and a trialkylborate ester (for example, U.S. Pat.No. 3,651,146), and a method by reacting phenyllithium with boron trifluoride ethyl ether complex (for example, A ., 563, 1949, P110) etc.

However, the use of ultrasonic waves is industrially unfavorable, and the use of trialkyl borate ester as a boron source has a drawback that the yield is low, and in the method using aryl lithium, tetraaryl borate ion is mainly used. There is a problem of generation. As described above, the conventional methods have the problems that the yield and purity of triarylboron are lowered and the reproducibility is poor.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have made various studies on the production conditions of triarylboron by the reaction of boron halide with arylmagnesium halide. Then, a synthetic study was carried out at a molar ratio of boron halide to arylmagnesium halide of 1: 3 described in the literature. As a result, the literature (eg, Inorg. Synth.,
15, 1947, P134), it was found that the yield and purity of triarylboron were low and reproducibility was poor. An object of the present invention is to improve such drawbacks and to provide a production method capable of obtaining a triarylboron in a higher yield and a higher purity.

[0006]

Means for Solving the Problems As a result of continuous studies, the present inventors have found that boron halide and arylmagnesium halide are present in an amount of 3.1 to 3.5 moles of arylmagnesium halide per mole of boron halide. By further removing the ether solvent from the reaction system by solidifying the magnesium halide salt produced as a by-product and liberating the triarylboron incorporated in the magnesium salt, a stable and high yield can be obtained. The inventors have found that triarylboron can be obtained and completed the present invention.

[0007] That is, the present invention is 0.1% in an organic solvent.
When reacting 〜8.0mol / L boron halide with 0.1〜3.0mol / L arylmagnesium halide, 3.1mol to 3.5mol of arylmagnesium halide is reacted with 1mol of boron halide, then ether. The present invention relates to a method for producing triarylboron, which comprises removing a system solvent from a reaction system to solidify a magnesium halide salt produced as a by-product and liberate triarylboron incorporated in the magnesium salt.

[0008]

The present invention will be described in detail below. Triarylboron is a boron compound represented by the general formula (I). R ₃ B (I) wherein R is the same or different and is an aryl group or a substituted aryl group, for example, phenyl, fluorophenyl, chlorophenyl, bromphenyl, methoxyphenyl, tolyl, xylyl, mesityl, biphenyl, naphthyl, Examples include pyridyl, trifluorophenyl, pentafluorophenyl group, tris (trifluoromethyl) phenyl group and the like.

Among the triaryl borons listed above, triphenyl boron and tris (pentafluorophenyl) boron are selected as particularly useful compounds. Triphenylboron is useful as a promoter for the hydroboration reaction of olefin compounds (for example, J. Am. Chem.
Soc., 1986, 108.7410 and J. Am. Chem. Soc., 1991,
113, 8570). Also, tris (pentafluorophenyl)
Boron is useful as a co-catalyst for polymerization (eg, Macr
Omol, Chem, Rapid Commun ,. 1991, 2, p. p663-667).

In the present invention, arylmagnesium halide is a compound represented by the general formula (II) ArMgX. Here, Ar represents the aryl group described above, and X represents halogen. Further, the solvent used for the arylmagnesium halide is preferably a chain ether. Particularly preferred is ethyl ether, which is easily distilled off.

In the present invention, usable boron halides include those represented by the general formula (III) BX ₃ . However, X is halogen here. Furthermore, coordination compounds such as ethers and thioethers of boron halides are also included in this. Since boron trichloride, boron tribromide, boron triiodide, and boron trifluoride have low boiling points, compounds such as ethyl ether complex are easier to handle,
desirable.

In the method of the present invention, a hydrocarbon solvent or a hydrocarbon solvent and a chain ether solvent are preferable as the organic solvent inert to the reaction product. As the hydrocarbon-based solvent, a saturated hydrocarbon-based solvent aromatic hydrocarbon, particularly an aromatic-based solvent such as xylene, toluene or benzene gives preferable results.

In the present invention, the concentration of boron halide is
When the concentration of aryl magnesium magnesium is 0.1 to 8.0 mol / L and the concentration of aryl magnesium is 0.1 to 3.0 mol / L, the productivity of the concentration of the reaction mixture does not significantly decrease, and the viscosity of the reaction mixture does not distill the ether solvent. It is not so disturbing that it gives particularly favorable results.

In the reaction of the present invention, when the boron halide reacts with the arylmagnesium halide, a solution of the arylmagnesium ether in an ether solvent is added dropwise to the boron halide dissolved in the aromatic solvent. React by the method.

In that case, the mixing temperature is preferably in the range of 15 to 65 ° C. If the mixing temperature is lower than 15 ° C, the produced triarylboron or the by-produced magnesium salt may be precipitated as crystals and hinder stirring. Further, when the mixing temperature exceeds 65 ° C., the yield often decreases. Further, the dropping time of arylmagnesium halide does not affect the yield of triarylboron.

Finally, by heating at 110 ° C. or higher to complete the reaction while removing ether from the reaction mixture, the reaction yield of triarylboron is improved and the magnesium salt by-produced is solidified. The triarylboron incorporated in the magnesium salt can be released to improve the recovery rate and also improve the reproducibility.

The reaction pressure may be normal pressure or pressure using an autoclave. However, considering that triarylboron is sensitive to oxygen and moisture, the reaction under pressure is more preferable in the sense of eliminating these influences.

[0018]

According to the present invention, in the reaction of arylmagnesium halide and boron halide, arylmagnesium halide is added to boron halide.
Triarylboron can be stably obtained with high purity and yield by using a slight excess of 3.1 equivalent.

The stability of the triarylboron formed when the amount of arylmagnesium halide used is less than 3.1 equivalents, or more than 3.5 equivalents, relative to the boron halide, as shown in the comparative examples described below. Deteriorates, resulting in a decrease in yield and purity. On the other hand, in the example, triannealed boron is stably obtained in high yield and high purity.

In the present invention, the significance of using a slight excess of arylmagnesium halide not only increases the yield of triarylboron, but also contributes to the increase in stability. This feature makes it possible to reproducibly produce triarylboron upon industrialization, which is a great advantage.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following examples, which are examples for specifically explaining the present invention, and the present invention is not limited to the following examples. Absent.

The yields of Examples 1 to 4 and Comparative Examples 1 and 2 below were obtained by an internal standard method using liquid chromatography after forming a stable complex by a reaction with butyl lithium. It is based on boron iodide.
In addition, in Example 3 and Comparative Example 3, since the complex formed from butyllithium is hygroscopic and unstable, it was further led to the form of tetramethylammonium salt or N, N-dimethylanilinium salt, and the dry weight yielded it. The rate was determined, and the yield and purity were determined by the internal standard method using the fluorine nuclear magnetic resonance spectrum. Particularly in Example 3, since the yield and purity of triarylboron itself were directly obtained by the internal standard method using the fluorine nuclear magnetic resonance spectrum, the values are also added.

Example 1 A 200 ml glass flask is equipped with a 50 ml glass dropping funnel and sufficiently replaced with nitrogen. Then, 30 ml of xylene that had been sufficiently degassed with nitrogen and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex were charged into the flask.
Also, 33.51 g (0.0647 mol) of a 35 wt% phenylmagnesium bromide in ethyl ether solution was charged into the dropping funnel. A solution of phenylmagnesium bromide in ethyl ether is dropped from a dropping funnel into the stirred reaction tank. The reaction temperature at that time was 18.6 to 29.9 ° C. After the dropping is completed,
The reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point, it was aged at that temperature for 1 hour, 3 hours, 5 hours, sampled respectively, and magnesium fluoride bromide was removed by a glass filter. When butyllithium was added to the liquid and the yields were calculated from the compounds obtained as stable complexes, the yields were 88.7%, 87.7%, and 86.2%, respectively.

Example 2 A 200 ml glass flask was equipped with a 50 ml glass dropping funnel and sufficiently replaced with nitrogen. Then, 30 ml of toluene that had been sufficiently degassed with nitrogen and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex were charged into the flask.
Also, 33.51 g (0.0647 mol) of a 35 wt% phenylmagnesium bromide in ethyl ether solution was charged into the dropping funnel. A solution of phenylmagnesium bromide in ethyl ether is dropped from a dropping funnel into the stirred reaction tank. The reaction temperature at that time was 18.6 to 29.9 ° C. After the dropping is completed,
The reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point, it was aged for 1 hour, 3 hours, and 5 hours at that temperature, sampled respectively, and magnesium fluoride bromide was removed with a glass filter. When butyllithium was added to the liquid and the yields were calculated from the compounds obtained as stable complexes, they were 91.0%, 90.7%, and 90.7%, respectively.

Example 3 A 200 ml glass flask was equipped with a 50 ml glass dropping funnel and sufficiently replaced with nitrogen. Then, 30 ml of toluene that had been sufficiently degassed with nitrogen and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex were charged into the flask.
Moreover, 84.99 g (0.0627 g) of 20 wt% pentafluorophenyl magnesium bromide in ethyl ether was added to the dropping funnel.
Mol). A solution of pentafluorophenylmagnesium bromide in ethyl ether is dropped from a dropping funnel into the stirred reaction tank. At that time, the reaction temperature was about 26 ° C and almost no exotherm was generated. After completion of dropping, the reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point of toluene, aging was carried out for 1 hour at that temperature, sampling was carried out for each, and magnesium fluorobromide was removed with a glass filter. The solvent was concentrated to dryness, and pentafluorotoluene was used as an internal standard substance in the fluorine nuclear magnetic resonance spectrum for quantification. The yield was 92%. The dry weight of the compound obtained by adding butyllithium to a light brown liquid and then adding an aqueous trimethylammonium chloride solution was 85% of the theoretical value. Also, instead of butyllithium, pentafluorobenzene bromide and butyllithium were reacted with pentafluorophenyllithium prepared at -70 ° C. in a mixed solvent of ethyl ether / hexane, and then N, N chloride
The dry weight of the compound obtained by adding an aqueous solution of dimethylanilinium was 85% of the theoretical value, and the yield was 85% when quantified using pentafluorotoluene as the internal standard substance in the fluorine nuclear magnetic resonance spectrum.

Example 4 A 200 ml glass flask was equipped with a 50 ml glass dropping funnel and sufficiently replaced with nitrogen. Then, 30 ml of toluene that had been sufficiently degassed with nitrogen and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex were charged into the flask.
Further, 61.42 g (0.0619 mol) of a 20 wt% p-tolylmagnesium bromide solution in ethyl ether was charged into the dropping funnel. A solution of p-tolylmagnesium bromide in ethyl ether is added dropwise to the stirred reaction tank from a dropping funnel. At that time, the reaction temperature was about 20 to 30 ° C and almost no heat generation. After completion of dropping, the reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point, it was aged for 3 hours at that temperature, magnesium fluoride bromide was removed by a glass filter, and then butyllithium was added to a light yellow transparent liquid to obtain a stable complex. When the yield was determined from the compound obtained as above, the yield was 89.6%, and when the purity was measured by liquid chromatography, the area percentage was 91.6%.

Comparative Example 1 A 200 ml glass flask was equipped with a 50 ml dropping funnel made of glass and sufficiently replaced with nitrogen. Then, 30 ml of toluene that had been thoroughly degassed by bubbling nitrogen through the flask and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex.
Charged. Also, 30.83 g (0.0597 mol) of a 35 wt% phenylmagnesium bromide in ethyl ether solution was charged into the dropping funnel. A solution of phenylmagnesium bromide in ethyl ether is dropped from a dropping funnel into the stirred reaction tank. After completion of dropping, the reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point of the solvent, it was aged at that temperature for 1 hour, 3 hours, and 5 hours, respectively sampled, and the yield was determined by the above-mentioned method. , 86.5%, 83.8%, and a decreasing tendency was observed in the yield. In addition, an increase in by-products derived from fluorodiphenylborane was observed with the increase in aging time.

Comparative Example 2 A 200 ml glass flask was equipped with a 50 ml glass dropping funnel and sufficiently replaced with nitrogen. Then, 30 ml of toluene that had been thoroughly degassed by bubbling nitrogen through the flask and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex.
Charged. Further, 38.23 g (0.0738 mol) of a 35 wt% phenylmagnesium bromide in ethyl ether solution was charged into the dropping funnel. A solution of phenylmagnesium bromide in ethyl ether is dropped from a dropping funnel into the stirred reaction tank. After completion of dropping, the reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point of the solvent, it was aged at that temperature for 1 hour, 3 hours, 5 hours, sampled, and the yield was determined by the above-mentioned method. , 64.5%, 64.5%, the yield was low, but there was almost no tendency to decrease.

Comparative Example 3 A 200-ml glass flask was equipped with a 50-ml glass dropping funnel and sufficiently replaced with nitrogen. Then, 30 ml of toluene that had been sufficiently degassed with nitrogen and 2.78 g (0.0196 mol) of boron trifluoride ethyl ether complex were charged into the flask.
In addition, 79.67 g (0.0588) of a 20 wt% pentafluorophenyl magnesium bromide in ethyl ether solution was added to the dropping funnel.
Mol). A solution of pentafluorophenylmagnesium bromide in ethyl ether is dropped from a dropping funnel into the stirred reaction tank. At that time, the reaction temperature was about 26 ° C and almost no exotherm was generated. After completion of dropping, the reaction tank was heated to remove ethyl ether.

After the temperature of the reaction tank reached the boiling point of toluene, aging was carried out for 1 hour at that temperature, sampling was carried out for each, and magnesium fluorobromide was removed with a glass filter. Add butyllithium to the light brown liquid,
Then, the dry weight of the compound obtained by adding an aqueous trimethylammonium chloride solution was 65% of the theoretical value.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiichi Kaji 1-1-1, 31, Shinmae, Shinnanyo-shi, Yamaguchi Prefecture Shinshin Dormitory (72) Kenji Ishimaru 1-1-1, 31-1, Shinmae, Shinnanyo, Yamaguchi Prefecture Dormitory

Claims (1)

[Claims] 1. A 0.1 to 3.0 mol / l boron halide and 0.1 to 3.0 mol in an organic solvent inert to the reactants.
When reacting a chain ether solvent solution of / L arylmagnesium halide, from 3.1 mol of arylmagnesium halide to 1 mol of boron halide.
It is characterized by improving the recovery rate by reacting 3.5 mols and then distilling off the chain ether solvent from the reaction system to allow the reaction to proceed sufficiently and to further crystallize the by-produced magnesium halide salt. A method for producing high-purity triarylboron in high yield.