JP2535776B2 - Process for producing 4- (4'-hydroxyphenyl) cinnamic acid ester - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 4- (4'-hydroxyphenyl) cinnamic acid esters. More specifically, it relates to a method for producing 4- (4'-hydroxyphenyl) cinnamic acid esters by reacting 4'-hydroxy-4-bromobiphenyl with acrylic acid esters in the presence of a nickel catalyst.

[0002]

2. Description of the Related Art Polymer liquid crystals are expected to be applied as a polymer material having excellent mechanical strength and heat resistance, and to photoreactive materials such as nonlinear optical elements and optical devices, and many studies have been conducted. There is. Of these, many of the main chain type polymer liquid crystal compounds have a structure in which a mesogenic group is connected by a spacer group. In synthesizing a polymer liquid crystal having such a structure, it is effective to use a low molecular weight compound having a mesogen group and a polymerizable functional group as a monomer and carry out the polymerization of those monomers. The low-molecular weight compound selected at this time is, as with ordinary low-molecular-weight liquid crystals, basically selected in that it has various mesogenic groups in its structure, and that the shape of the molecule is close to a straight line. , At the same time, for the production of macromolecules by polymerization, double bonds of addition-polymerizable functional groups,
It is necessary to have a carboxylic acid or a hydroxyl group for polymerization by dehydration condensation.

Hydroxycarboxylic acid esters having a biphenyl skeleton, which are effective as a mesogenic group, such as 4- (4'-hydroxyphenyl) cinnamic acid and its esters, are low molecular weight compounds having a structure satisfying these conditions. However, a method for efficiently producing these compounds using an inexpensive catalyst has not been proposed.

As a method for introducing a vinyl group into an aromatic nucleus, a Heck reaction using a palladium catalyst has been reported (RF Heck and JP Nolly, Jr., J. Org. Chem.,
37, 2320 (1972)). This method involves reacting an aromatic bromide or iodide with an olefin by reacting a palladium catalyst in the presence of a base.
The present inventors have also found that the Heck-type vinylation reaction using a palladium catalyst is effective also for the reaction of 4′-hydroxy-4-bromobiphenyl with acrylic acid esters, and at that time, a special base for the reaction is used. It was found that there was an effect, and a method for efficiently producing 4- (4'-hydroxyphenyl) cinnamic acid esters using a palladium catalyst was reported (Japanese Patent Application No. 5-125426).

However, palladium is one of the noble metals, and considering the recovery of the catalyst and the like, it is desirable to carry out the reaction with a cheaper metal as the catalyst. In this respect, nickel is an element of the same family as palladium, and is known to exhibit the same catalytic activity as palladium in hydrogenation reaction, carbonylation reaction and the like. However, a method of directly introducing a vinyl group into an aromatic bromide or iodide by a nickel catalyst alone has not been known so far.
In the known vinylation reaction of aromatic halides with nickel complexes, the nickel complex catalyst alone stops the reaction at an early stage.Therefore, in order to proceed the reaction continuously, the presence of a reducing agent such as zinc should be considered. (SA Lebeder
Et al., Journal of Organometallic Chemistry, 344
Vol. 253, 1988), or electrode reaction (Y. Rol
lin et al., Tetrahedron Letters, 23, 3573,
(1982), it has been reported that it is necessary to reduce divalent nickel species to zero valence.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently producing 4- (4'-hydroxyphenyl) cinnamic acid esters with an inexpensive catalyst, which uses a nickel catalyst. It is intended to provide a method for promoting the reaction of 4′-hydroxy-4-bromobiphenyl and acrylic acid esters by a Heck type reaction without using a reducing agent and without depending on an electrode reaction.

[0007]

In order to solve the above problems, the inventors of the present invention have keenly sought a method of smoothly promoting the reaction of 4'-hydroxy-4-bromobiphenyl and acrylic acid esters with a nickel catalyst. investigated. as a result,
The present invention has been completed by finding a method for advancing the vinylation reaction of an aromatic halide with a nickel catalyst without adding a reducing agent or an electrode reaction.

That is, according to the present invention, in the presence of a nickel catalyst and a base, 4'-hydroxy-4-bromobiphenyl and acrylic acid esters are represented by the following formula (II).

[0009]

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(Wherein R ₁ represents a straight-chain or branched alkyl group having 1 to 10 carbon atoms), and 4- (4'-hydroxyphenyl) cinnamic acid esters are reacted. To provide a method of manufacturing.

Next, a method for solving the problems according to the present invention will be described in detail. The acrylic acid ester used in the present invention has a linear or branched alkyl group having 1 to 10 carbon atoms in the ester group, and specifically,
Examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, octyl acrylate and the like. Of these, ethyl acrylate is preferred. The amount of acrylic acid ester used in the reaction in the method of the present invention is preferably stoichiometric with respect to 4'-hydroxy-4-bromobiphenyl.

Examples of the nickel catalyst used in the method of the present invention include, but are not limited to, nickel salts such as nickel chloride and nickel nitrate, and supported metal catalysts such as nickel supported on activated carbon. Of these, nickel salts are preferable, and nickel chloride is particularly preferable.
The amount of nickel catalyst used is determined in consideration of the activity of the catalyst.

In the present invention, a nickel complex catalyst having a ligand as a nickel catalyst is preferable, and examples of the compound used as a ligand with nickel alone include triphenylphosphine, tris (o-tolyl) phosphine,
Examples thereof include monodentate phosphine compounds such as tris (m-tolyl) phosphine and tris (p-tolyl) phosphine, and coordinating nitrogen compounds such as pyridine, quinoline, and isoquinoline, but are not limited thereto. Among these, monodentate phosphine compounds are preferable, and triphenylphosphine is particularly preferable. When a ligand is used in the present invention, the amount of the ligand used with respect to the nickel catalyst is important and is determined by the reaction activity, the type of the ligand and the base. For example, the amount of a monodentate phosphine compound such as triphenylphosphine used is
The ligand is used in an amount not exceeding 2 equivalents with respect to the nickel metal.

The method of the present invention is preferably carried out in a solvent. Specific examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N'-dimethylimidazolidone, aprotic polar solvents such as acetonitrile, benzene,
An aromatic solvent such as toluene may be used. An aprotic polar solvent such as N-methyl-2-pyrrolidone or N, N′-dimethylimidazolidone is preferably used as the solvent. The amount of solvent used is arbitrarily determined depending on the reaction container and the amount of reaction substrate. There is no particular limitation.

In the method of the present invention, the reaction is carried out in the presence of a base which absorbs hydrobromic acid generated by the reaction. Specific examples of the base include inorganic bases such as sodium carbonate, sodium hydrogen carbonate, lithium carbonate, sodium acetate and potassium acetate, and organic bases such as triethylamine and tributylamine. Among these, the inorganic base is preferable,
Particularly preferred is sodium carbonate. However, potassium carbonate,
Potassium hydrogen carbonate causes a large decrease in activity and is not preferred as the inorganic base.

The reaction time is arbitrarily determined in consideration of the progress of the reaction depending on the experimental conditions such as the catalyst, the ligand compound and the solvent used.

The reaction temperature is arbitrarily determined according to the activity of the catalyst, the reaction rate, the stability of the ligand compound, etc., but is preferably in the range of 140 to 180 ° C.

In the method of the present invention, the reaction can be carried out in a batch type reaction apparatus. In this case, an autoclave is usually used. Further, in consideration of the reaction temperature and the boiling point of the solvent, a non-sealed reaction vessel is under normal pressure. Can also be carried out. The reaction solution is preferably stirred during the reaction. As a method of stirring, any method such as vertical stirring, rotary stirring, and shaking stirring can be used depending on the reaction vessel. Further, the reaction is preferably carried out under an inert atmosphere such as nitrogen.

The reaction mixture obtained by such a reaction is the desired 4- (4 ') represented by the general formula (I).
In addition to (hydroxyphenyl) cinnamic acid esters, it contains a catalyst residue, a base, a reaction product of a base and hydrobromic acid, and by-products such as 4-hydroxybiphenyl depending on reaction conditions. Impurities can be removed from the reaction mixture by a known method such as ordinary extraction operation, distillation, and column chromatography to purify the desired ester.

[0020]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples. In the following examples, the quantification of the reaction was carried out by the internal standard method by Hewlett-Packard 589.
Using a 0 type gas chromatograph, the gas chromatograph mass spectrum is 589 manufactured by Hewlett-Packard.
A 5971A mass spectrometric detector manufactured by the same company was attached to the 0 type gas chromatograph, and each measurement was performed.

Example 1 4'-Hydroxy-4-bromobiphenyl 10mmo
1, ethyl acrylate 12.5 mmol, nickel chloride 0.1 mmol, N-methyl-2-pyrrolidone 15
cm ³ , sodium carbonate 12.5 mmol, and triphenylphosphine 0.2 mmol, internal volume 100
It was placed in a magnetic stirring autoclave manufactured by SUS-316. After replacing the inside of the reaction vessel with nitrogen, raise the temperature to 160
When the temperature reached ℃, stirring was started. Then, the temperature was maintained at 160 ° C. for 19 hours with further stirring. After the reaction, the reactor was gradually cooled, the contents were taken out using a solvent, and the reaction rate and the yield were determined by gas chromatography using 2-methylnaphthalene as an internal standard. The results are shown in Table 1. The melting point of the obtained compound, 4- (4′-hydroxyphenyl) cinnamic acid ester, was 133 to 134 ° C. (uncorrected).

Examples 2 to 12 Under the conditions shown in Tables 1 and 2, the same reaction as in Example 1 was performed. In these reactions, 10 mmol of 4'-hydroxy-4-bromobiphenyl, 12.5 mmol of ethyl acrylate, 0.1 mmol of nickel as a catalyst, and a predetermined amount of solvent, base and coordination compound in an internal volume of 100 ml. It was put in a magnetic stirring type autoclave made of SUS-316. After replacing the inside of the reaction vessel with nitrogen, the temperature was raised, and when the temperature reached a predetermined reaction temperature, stirring was started. Thereafter, this temperature was maintained for 19 hours while further stirring. After the reaction, the reactor was gradually cooled, the contents were taken out using a solvent, and the reaction rate and the yield were determined using 2-methylnaphthalene as an internal standard. The results are shown in Tables 1 and 2 together with the reaction conditions.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

EFFECTS OF THE INVENTION According to the method of the present invention, 4- (4'-hydroxyphenyl) cinnamic acid esters, which are important as intermediates for organic materials such as polymer liquid crystals, are efficiently produced by an inexpensive nickel catalyst. be able to.

Front page continued (72) Inventor Kazuhiko Takeuchi, 1-1 Higashi, Tsukuba, Ibaraki, Institute of Industrial Science and Technology, Institute of Materials Engineering (72) Inventor Yoshihiro Sugi, 1-1, Higashi, Tsukuba, Ibaraki, Industrial Technology Industrial Engineering Inside the Institute (72) Inventor Ashtosh Anant Kerker Inside the Institute of Materials Engineering and Industrial Technology, 1-1, Higashi, Tsukuba City, Ibaraki Prefecture (72) Inventor Tomoyuki Hatanaka 2641 Yamazaki, Noda, Chiba Tokyo University of Science (72) Inventor Yoshibe Abe 2641 Yamazaki, Noda City, Chiba, Tokyo University of Science (72) Inventor, Misao Toshihisa, 2641 Yamazaki, Noda City, Chiba Tokyo University of Science

Claims (2)

(57) [Claims] 1. A 4'- in the presence of a nickel catalyst and a base.
The following general formula (I) is characterized in that hydroxy-4-bromobiphenyl is reacted with acrylic acid esters. (In the formula, R ₁ represents a linear or branched alkyl group having 1 to 10 carbon atoms.) A method for producing 4- (4′-hydroxyphenyl) cinnamic acid esters. 2. The method according to claim 1, wherein the nickel catalyst has a ligand.