JP2669666B2 - Novel optically active ester compound, intermediate therefor, method for producing the same, and liquid crystal composition containing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel optically active ester compound useful as a liquid crystal material, an intermediate therefor, a method for producing the same, and a liquid crystal composition containing the same.

[Prior Art] Currently, liquid crystal materials are widely used for display devices, but most of these liquid crystal display devices are of a TN (Twisted Nematic) type display system using a nematic liquid crystal.
However, this method has a drawback that the response speed is slow, and the response speed is only about several milliseconds at most.

For this reason, various liquid crystal display methods based on another principle instead of the TN type display method have been tried. One of them is a display method using a ferroelectric liquid crystal [NAClark et al .; Applied Phys.
t.36,899 (1980)]. This method utilizes a ferroelectric chiral smectic phase, particularly a chiral smectic C phase, and has attracted attention for high-speed optical switching. Some of such ferroelectric liquid crystal materials have already been known (for example, Japanese Patent Application Laid-Open No. 32748/1985), but none of them exhibit sufficiently satisfactory properties.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel optically active ester compound having sufficiently satisfactory properties such as fast response speed and chemical stability as a liquid crystal material suitable for an optical switching system. , A method for producing the same, an intermediate therefor, and a liquid crystal composition containing them.

[Means for Solving the Problems] The inventors of the present invention have conducted research to solve the above problems, and as a result, have found a specific group of compounds, and have completed the present invention.

That is, the present invention provides (1) the general formula (I) Wherein R represents an alkoxy group having 20 or less carbon atoms, n represents an integer of 1 or 2, and * represents an asymmetric carbon atom. (2) Formula (II) (However, * represents an asymmetric carbon atom) p- [2- (4-methylcyclohexyl-)
1), propoxy] benzoic acid, (3) Formula (II) (However, * represents an asymmetric carbon atom) p- [2- (4-methylcyclohexyl-)
1) Propoxy] benzoic acid and general formula (III) Wherein R is an alkoxy group having 20 or less carbon atoms and n is an integer of 1 or 2; and a phenol represented by the following general formula (I): (Wherein R represents an alkoxy group having 20 or less carbon atoms, n represents an integer of 1 or 2, and * represents an asymmetric carbon atom), a method for producing an optically active ester compound, (4) the general formula ( I) (Where R represents an alkoxy group having 20 or less carbon atoms, n represents an integer of 1 or 2, and * represents an asymmetric carbon atom).

The greatest feature of the ester compound of the present invention represented by the general formula (I) is that it contains a cyclohexyl group having an asymmetric carbon. The conventional ferroelectric liquid crystal compound also contains asymmetric carbon, but in the case of the conventional compound, the asymmetric carbon source is an alkyl group such as active amyl alcohol. By using a silcohexyl group as an asymmetric carbon source like the compound of the present invention, 1) the viscosity is reduced, 2) the spontaneous polarization is increased due to the steric effect of the asymmetric source, and as a result, the response speed is dramatically improved. be able to.

As described above, in the optically active ester compound of the general formula (I), n is 1 or 2, and R is alkoxy having 1 to 20 carbon atoms. Is shown in Table-1.

These compounds of the general formula (I) are generally of the formula (II)
[2- (4-methylcyclohexyl-1) propoxy]
Benzoic acid and the phenol of the general formula (III) are N, N '
-It is obtained by reacting at room temperature using a condensing agent such as disyllohexylcarbodiimide. As a solvent, tetrahydrofuran, methylene chloride, 1,2-dichloroethane, acetone tolyl or the like is used. Note that the formula (II)
The ratio of the compound of the formula (III) to the compound of the formula (III) may be a stoichiometric amount.

The compound of formula (II) can be obtained, for example, according to the following reaction formula.

First, p-hydroxybenzoic acid benzyl ester (I
V) and optically active P-toluenesulfonic acid-2- (4-
By reacting methyl-3-cyclohexenyl-1) propyl ester (V) in the presence of a basic catalyst such as sodium hydride or caustic potash, optically active p- [2- (4-
Methylcyclohexenyl-1) propoxy] benzoic acid benzyl ester (VI) is obtained.

The p-toluenesulfonic acid-2- (4-methyl-3-cyclohexenyl-1) propyl ester (V)
Is a conventional method, that is, p-toluenesulfonic acid chloride is reacted with commercially available (R, R) 2- (4-methyl-3-cyclohexenyl-1) propanol in the presence of a basic catalyst such as pyridine. It is obtained by Next, the optically active p- [2- (4-methyl-3-cyclohexenyl-
1) Propoxy] benzoic acid benzyl ester (VI) to Pd
-Obtained by reduction in the presence of a reduction catalyst such as carbon.

The optically active ester compound of the present invention represented by the general formula (I) exhibits excellent performance as a ferroelectric liquid crystal material, has a fast response speed, shows very good alignment, and is chemically stable.

Although the novel chemically active ester compound represented by the general formula (I) of the present invention can be used alone as a ferroelectric liquid crystal material, it can be mixed with another liquid crystal material, especially a ferroelectric liquid crystal material to improve the performance. It can be a thing. The liquid crystal composition containing the compound of the present invention is used not only for display but also for various electro-optical devices such as an electro-optical shutter, an electro-optical stop, an optical modulator, an optical communication optical path switch, a memory, and a variable focal length lens. It can be suitably used in the field of optoelectronics.

Among other liquid crystal compounds that can be used in combination with the compound of the present invention,
Table 2 shows a ferroelectric chiral smectic phase.

[Examples] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The value of the phase transition temperature in the examples slightly varies depending on the measuring method and the purity of the chemical.

Example 1 Compound No. (2) in Table 1 above {optical activity p-
[2- (4-methylcyclohexyl-1) propoxy]
Preparation of benzoic acid-p'-n-hexyloxyphenyl ester A. Optically active p- [2- (4-methyl-3-cyclohexenyl-1) propoxy] benzoic acid benzyl ester (V
Preparation of I) 25.11 g of p-hydroxybenzoic acid benzyl ester (0.
11 mol) was dissolved in 100 ml of dry N, N-dimethylformamide, and 6 g of 60% sodium hydride was added thereto while stirring with cooling.
(0.15 mol) was added, followed by optically active p-toluenesulfonic acid-2- (4-methyl-3-cyclohexenyl-).
1) Add 30.84 g (0.1 mol) of propyl ester and add 50 to 6
The mixture was reacted at 0 ° C. for 4 hours with stirring. After the reaction is complete, water 5
00 ml and 300 ml of toluene were added and well stirred, and the separated toluene layer was washed with 6N-HCl and subsequently washed with water until it became neutral. After the toluene layer was dried over anhydrous magnesium sulfate, the toluene was distilled off, and the residue was subjected to silica gel column chromatography using toluene as a developing solvent to obtain 26.72 g of a crude target product (VI).

B. Optical activity p- [2- (4-methylcyclohexyl-
1) Production of propoxy] benzoic acid (II) p- [2- (4-methyl-3-cyclohexenyl-1) propoxybenzoic acid benzyl ester 2 obtained in the above A
6.72 g was dissolved in a mixed solvent of 200 ml of 1,4-dioxane and 200 ml of ethanol, and subjected to catalytic hydrogenation at room temperature in the presence of 4.01 g of Pd-carbon. Two times moles of hydrogen were required. After completion of the reaction, Pd-carbon was removed by filtration, the solvent was distilled off, and the residue was recrystallized twice from acetonitrile to obtain 13.74 g of the desired product (II). Properties of Compound (II) Melting point: 126.0-127.5 ° C Optical rotation [α] ^D (-) 2.90 ゜ (chloroform) Elemental analysis Calculated value C (%) 73.87 73.88 H (%) 8.69 8.75 The structure of this compound is Confirmed by infrared absorption spectrum. FIG. 1 shows the infrared absorption spectrum.

C. Production of Compound [No. (2)] 1.66 g (0.006 mol) of p- [2- (4-methylcyclohexyl-1) propoxy] benzoic acid obtained in B above,
1.17 g (0.006 mol) of n-hexyloxyphenol, N,
1.37 g of N'-dicyclohexylcarbodiimide and 0.15 g of 4-dimethylaminopyridine are stirred in 100 ml of methylene chloride at room temperature for 5 hours and left overnight. The crystals were filtered, and the residue obtained by distilling off methylene chloride was subjected to silica gel column chromatography using toluene as a developing solvent. The obtained crude target substance was recrystallized three times to obtain a pure target substance {compound [No. 2)]} 1.03 g was obtained.

Its structure was confirmed by infrared absorption spectrum.

Examples 2 to 4 Instead of 1.17 g of pn-hexyloxyphenol p
-N-octyloxyphenol 1.33 g, pn-decyloxyphenol 1.50 g, and pn-dodecyloxyphenol 1.67 g were used in the same manner as in Example 1, except that pure target compound No. (4) 0.94g, compound No.
0.86 g of (6) and 1.00 g of compound No. (7) were obtained.

Example 5 Compound [NO. (17)] {chemically active p- [2- (4-methylcyclohexyl-1) propoxy] benzoic acid-p'-
Production of ("p-dodecyloxyphenyl) phenyl ester.

1.66 g (0.006 mol) of p- [2- (4-methylcyclohexyl-1) propoxy] benzoic acid obtained in the above B,
Dodecyloxy-p'-hydroxybiphenyl 2.13 (0.
006 mol), N, N'-dicyclohexylcarbodiimide 1.
37 g and 0.15 g of 4-dimethylaminopyridine are stirred and reacted in 100 ml of methylene chloride at room temperature for 5 hours and left overnight. The crystals were filtered and methylene chloride was distilled off, and the residue was subjected to silica gel column chromatography using a developing solvent of toluene. The obtained crude target substance was recrystallized from a mixed solvent of ethanol-ethyl acetate three times to obtain a pure target substance. 1.01 g of substance {chemical substance [No, (17)]} was obtained. Its structure was confirmed by infrared absorption spectrum. FIG. 2 shows the infrared absorption spectrum.

Examples 6 to 12 Instead of p-dodecyloxy-p'-hydroxybiphenyl (2.13 g), p-hexyloxy-p'-hydroxybiphenyl (1.62 g), p-heptyloxy-p '
-Hydroxybiphenyl (1.71 g), p-octyloxy-p'-hydroxyphenyl (1.79 g), p-nonyloxy-p'-hydroxybiphenyl (1.87 g), p-
Decyloxy-p'-hydroxybiphenyl (1.96
g), p-tetradecyloxy-p′-hydroxybiphenyl (2.30 g) and p-hexadecyloxy-p′-hydroxybiphenyl (2.46 g) were used, but the pure product was obtained in the same manner as in Example 5. , Compound No. (12) (1.18g),
Compound No. (13) (0.98 g), Compound No. (14) (1.07 g)
g), Compound No. (15) (0.84 g), Compound No. (16) (1.
31g), Compound No. (18) (1.58g), Compound No. (19)
(1.27g) was obtained.

Table 3 shows the results of elemental analysis of the compound obtained as described above.

Table 4 shows the phase transition temperatures of the above compounds.

[Example of use] Example of use 1 After coating each electrode surface with polyvinyl alcohol (PVA), the two transparent electrodes that have been subjected to parallel alignment treatment by rubbing the surfaces face each other with a PVA film on the inner side at an interval of 3 μm. After injecting the optically active ester compound [Compound No. (16)] prepared in Example 10 in the formed cell,
When a liquid crystal display device was installed between two orthogonal polarizers and a voltage of 20V was applied between the electrodes, a clear and good contrast and fast response speed (about 100 μsec) were observed.

Use Example 2 A composition was prepared by mixing the compound No. (17) prepared in Example 5 with 36.0 wt% of p-octyloxybenzoic acid-p'-n-hexyloxyphenyl ester. The phase transition points of this composition were as follows.

71 ° C. 94 ° C. ← SmC * NI SmC *: Ferroelectric smectic C phase N: Nematic phase I: Isotropic liquid [Effect of the invention] The chemically active ester compound represented by the general formula (I) of the present invention is It is useful as a liquid crystal material having a high speed. Particularly, a compound of n = 2 exhibits a ferroelectric smectic C phase by itself and has a fast response speed (about 100 μs). It can be said that it is a material.

Further, since the compound of the general formula (I) has an optically active carbon atom, it has an ability to induce a twisted structure by adding it to a nematic liquid crystal. A nematic liquid crystal having a twisted structure, that is, a chiral nematic liquid crystal, is a so-called reverse domain of a TN type display device.
Compounds of general formula (I) can be used as inhibitors of reverse domain formation since they do not produce n).

[Brief description of the drawings]

FIG. 1 shows the optically active p- [2-
FIG. 2 shows the infrared absorption spectrum of (4-methylcyclohexyl-1) propoxy] benzoic acid. FIG. 2 shows the optically active p- [2- (4-methylcyclohexyl-) obtained in Example 5.
1) Infrared absorption spectrum of 1) propoxy] benzoic acid-p '-(p "-dodecyloxyphenyl) phenyl ester.

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Claims (4)

(57) [Claims] 1. The compound of the general formula (I) (Where R represents an alkoxy group having 20 or less carbon atoms, n represents an integer of 1 or 2, and * represents an asymmetric carbon atom). 2. Formula (II) (However, * represents an asymmetric carbon atom) p- [2- (4-methylcyclohexyl-)
1) Propoxy] benzoic acid. 3. The formula (II) (However, * represents an asymmetric carbon atom) p- [2- (4-methylcyclohexyl-)
1) Propoxy] benzoic acid and general formula (III) (Where R represents an alkoxy group having 20 or less carbon atoms, and n represents an integer of 1 or 2). A phenol represented by the following general formula (I): (Where R represents an alkoxy group having 20 or less carbon atoms, n represents an integer of 1 or 2, and * represents an asymmetric carbon atom). 4. The formula (I) (Where R represents an alkoxy group having 20 or less carbon atoms, n represents an integer of 1 or 2, and * represents an asymmetric carbon atom).