JP2003183192A - Method for manufacturing 3-alkenyl-4-chlorobenzene compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easy and low cost method for manufacturing a 3- alkenyl-4-chlorobenzene. <P>SOLUTION: This method for manufacturing the 3-alkenyl-4-chlorobenzene of formula (III), [wherein Fn means that optional hydrogen atoms in the benzene ring may be substituted with fluorine atoms; and R shows a 1-20C saturated or unsaturated alkyl group which may be substituted with at least one fluorine atom and/or a 1-7C alkoxy group, and may involves branched chains] by reacting 4-chlorobenzylmagnesium chloride with a 2-alkenyl compound. Up to now, the 3-alkenyl-4-chlorobenzene compound has been not easily available and obtained by complicated methods, but now it can be easily prepared industrially by the only one step process at a low cost. The 3-alkenyl-4-chlorobenzene compound is quite useful as a raw material for manufacturing a liquid crystal display material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to (3-alkenyl) -4-
The present invention relates to the selective production of chlorobenzene compounds.

[0002]

2. Description of the Related Art (3-Alkenyl) -4-chlorobenzene compounds are useful as intermediates for the production of many liquid crystal materials including the compounds shown below.

[Chemical 4]

However, a simple method for producing a (3-alkenyl) -4-chlorobenzene compound is not known, and in particular, a compound having a high content of E-form, which is useful as an intermediate for liquid crystal materials, is selectively produced. Was difficult. Since the production of (3-alkenyl) -4-chlorobenzene compounds is difficult, the production of the above liquid crystal materials must use a complicated and expensive production method, which hinders the practical application of these compounds. Was there. Therefore, an easy and inexpensive method for producing a (3-alkenyl) -4-chlorobenzene compound having a high content of E-form has been demanded.

[0004]

The problem to be solved by the present invention is to provide an easy and inexpensive method for producing a (3-alkenyl) -4-chlorobenzene compound.

[0005]

Means for Solving the Problems The present invention has been made as a result of extensive studies to solve the above problems, and as a result, by reacting a benzyl Grignard reagent with an (E) -2-alkenyl compound, (3-alkenyl)- The inventors have found that a 4-chlorobenzene compound can be easily obtained, and completed the present invention.

That is, the present invention has the general formula (I)

[Chemical 5] (In the formula, Fn means that arbitrary hydrogen on the benzene ring may be replaced by fluorine.) The 4-chlorobenzylmagnesium chloride represented by the general formula (II)

[Chemical 6] (In the formula, X represents a chlorine atom, a bromine atom, an iodine atom or a sulfonyloxy group, and R represents one or more fluorine atoms and
/ Or a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, which may be substituted with an alkoxyl group having 1 to 7 carbon atoms and may include a branched chain. ) Represented by 2-
General formula (III) characterized by reacting an alkenyl compound

[Chemical 7] (In the formula, Fn means that any hydrogen on the benzene ring may be replaced by fluorine, and R is substituted by at least one fluorine atom and / or an alkoxyl group having 1 to 7 carbon atoms. Or a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, which may include a branched chain.), And a method for producing a (3-alkenyl) -4-chlorobenzene compound.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, 4-chlorobenzylmagnesium chloride represented by the general formula (I) and the general formula (I
In the reaction with the 2-alkenyl compound represented by I), as a solvent, tetrahydrofuran (THF), diethyl ether, diisopropyl ether, ether solvents such as methyl t-butyl ether and hexane, heptane, saturated hydrocarbons such as octane, Aromatic solvents such as benzene, toluene, xylene and mesitylene may be used alone or in combination, and tetrahydrofuran is preferred.

The reaction temperature may be in the range of reflux temperature from the freezing point of the solvent, but -20 ° C to room temperature is preferable.

The steric double bond of the compound (III) produced in the present invention is E-form, Z-form or a mixture thereof depending on the selection of the steric form in the compound (II). is there.

X in the compound (II) represents a chlorine atom, a bromine atom, an iodine atom or a sulfonyloxy group, and as the sulfonyloxy group, a methanesulfonyloxy group, a benzenesulfonyloxy group, a p-toluenesulfonyloxy group or the like is used. The chlorine atom and the bromine atom are preferable because they can be obtained, are easily available, and are easy to handle.

R in the compounds (II) and (III) may be substituted with an alkoxyl group having 1 to 7 carbon atoms and may have a branched or branched chain.
~ 20 represents an alkyl group, examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, Linear alkyl group such as tridecyl group, 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-methylpentyl group, 2 -
Methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, 1-methylhexyl group, 2-methylhexyl group, 3-
Methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 1-methylheptyl group, 2-methylheptyl group, 3-
Methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 6-methylheptyl group, 1-methyloctyl group, 2-
Methyloctyl group, 3-methyloctyl group, 4-methyloctyl group, 5-methyloctyl group, 6-methyloctyl group, 7-
Branched alkyl groups such as methyloctyl group, 1-ethylpropyl group, 1-ethylbutyl group, 2-ethylbutyl group, ethenyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 3 -Butenyl group, 1-pentenyl group, 2-
Pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-heptenyl group, 2-heptenyl group, 3- An unsaturated alkyl group such as a heptenyl group, a 4-heptenyl group, a 5-heptenyl group, a 6-heptenyl group, and an alkyl group substituted with a fluorine atom and / or an alkoxyl group having 1 to 7 carbon atoms can be used. However, a linear alkyl group is preferable, and a methyl group, an ethyl group, and a propyl group are particularly preferable.

The 4-chlorobenzylmagnesium chloride represented by the general formula (I), which is the starting material of the present invention, is heated exothermically by adding a tetrahydrofuran solution of 1,2-dibromoethane to magnesium powder at room temperature to give magnesium. After activating the powder surface, the general formula (IV)

[Chemical 8] (In the formula, Fn means that arbitrary hydrogen on the benzene ring may be replaced with fluorine.) It can be prepared by slowly adding a tetrahydrofuran solution of 4-chlorobenzyl chloride.

For activation of magnesium powder, 1,2-diiodoethane, dibromomethane, diiodomethane, iodine or bromine can be used instead of 1,2-dibromoethane. Further, active magnesium such as naphthalene-magnesium complex or anthracene-magnesium complex can also be used.

When adding a tetrahydrofuran solution of 4-chlorobenzyl chloride represented by the general formula (IV) to magnesium powder, the general formula (V)

[Chemical 9] (In the formula, Fn means that any hydrogen on the benzene ring may be replaced by fluorine.) In order to suppress the formation of the above, it is preferable to keep the temperature at -10 ° C or lower, and -20 to -35 ℃
It is particularly preferable to keep.

As the solvent, tetrahydrofuran (THF)
Besides, ether solvents such as diethyl ether, diisopropyl ether and methyl t-butyl ether, saturated hydrocarbons such as hexane, heptane and octane, aromatic solvents such as benzene, toluene, xylene and mesitylene may be used alone or mixed. Although it can be used, tetrahydrofuran is preferred.

4-Chlorobenzyl chloride represented by the general formula (IV) is a general compound in organic synthesis and is easily available.

In the (E) -2-alkenyl compound represented by the general formula (II), those in which X is chlorine, bromine or iodine are general compounds in organic synthesis and are easily available. In addition, the general formula (VI)

[Chemical 10] (In the formula, R may be substituted with at least one fluorine atom and / or an alkoxyl group having 1 to 7 carbon atoms, and may have a branched chain.
Represents an alkyl group of 20. ) Can be easily synthesized by halogenating the alcohol.

When X is a sulfonyloxy group in compound (II), it can be synthesized by sulfonylating the above alcohol.

[0019]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 Synthesis of (E) -4- (3-pentenyl) chlorobenzene (1)

[Chemical 11] Under a nitrogen atmosphere, add magnesium powder (2.3 g, 93 mmo) to a reaction vessel equipped with a mechanical stirrer, Dimroth, and thermometer.
l) and THF (5 ml) were added, 1,2-dibromoethane (2.3 g, 12 mmol) was added dropwise with vigorous stirring, and the mixture was further stirred for 10 minutes. After cooling to -25 to -30 ℃, with vigorous stirring 4-chloride
Add 2.5 parts of chlorobenzyl (10 g, 62 mmol) in THF (55 ml).
The solution was added dropwise over a period of time and stirred for 3.5 hours. The temperature was raised to 5 ° C, and (E) -crotyl chloride (8 ml, 61 mmol) in THF (10 ml).
The solution was added dropwise over a period of time, and the mixture was further stirred at room temperature for 1 hr. Pour the reaction solution into 10% hydrochloric acid, separate the organic layer,
The aqueous layer was extracted with hexane (50 ml), the organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated. The residue was distilled under reduced pressure (60 ° C / 0.3 Torr) to obtain (E) -4- (3-pentenyl) chlorobenzene (6.5 g, 58%) as a colorless oily substance. ¹ H NMR (400 MHz, CDCl ₃ ): δ 1.64 (d, J = 3.2 Hz, 3
H), 2.2-2.4 (m, 2 H), 2.63 (t, J = 7.8 Hz, 2 H), 7.
10 (d, J = 8.3 Hz, 2 H), 7.24 (d, J = 8.3 Hz, 2 H) MS m / z: 180 (M ⁺ ), 125 (100)

Example 2 Synthesis of (E) -4- (3-pentenyl) chlorobenzene (2) Example 1 except that (E) -crotyl bromide was used instead of (E) -crotyl chloride. (E) -4- (3-Pentenyl) chlorobenzene was obtained under the same conditions as above.

Example 3 Synthesis of (E) -4- (3-pentenyl) chlorobenzene (3) (E) -crotyl alcohol (4.4 g, 61 mmol) in THF (10 m
l) To the solution at 0 ° C., add triethylamine (6.2 g, 61 mmol) and methanesulfonyl chloride (7.0 g, 61 mmol), and add 1
After stirring for an hour, the reaction solution was filtered through Celite. This filtrate was used instead of the THF solution of (E) -crotyl chloride in Example 1 to obtain (E) -4- (3-pentenyl) chlorobenzene.

[0023]

According to the present invention, it is difficult to obtain until now,
The (3-alkenyl) -4-chlorobenzene compound, which has a complicated production method, can be produced industrially easily and inexpensively in one step. This (3-alkenyl) -4-chlorobenzene compound is extremely useful as a raw material for producing a liquid crystal display material.

Claims (4)

[Claims] 1. A compound represented by the general formula (I): (In the formula, Fn means that any hydrogen on the benzene ring may be replaced by fluorine.) The 4-chlorobenzylmagnesium chloride represented by the general formula (II) (In the formula, X represents a chlorine atom, a bromine atom, an iodine atom or a sulfonyloxy group, and R represents one or more fluorine atoms and
/ Or a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, which may be substituted with an alkoxyl group having 1 to 7 carbon atoms and may include a branched chain. ) Represented by 2-
A compound of the general formula (III): characterized by reacting an alkenyl compound (In the formula, Fn means that any hydrogen on the benzene ring may be replaced by fluorine, and R is substituted by at least one fluorine atom and / or an alkoxyl group having 1 to 7 carbon atoms. Or a saturated or unsaturated alkyl group having 1 to 20 carbon atoms, which may include a branched chain.), Which is a (3-alkenyl) -4-chlorobenzene compound. 2. In the general formula (II) and the general formula (III),
2. The production method according to claim 1, wherein the stereo structure of the double bond is an E-form. 3. The method according to claim 1, wherein the reaction is carried out at −20 ° C. to room temperature.
The manufacturing method described in 2. 4. The production method according to claim 1, 2 or 3, wherein X in the general formula (II) represents a chlorine atom or a bromine atom.