JPH0778042B2 - Pyrimidine compound - Google Patents

Description

The present invention relates to an optically active pyrimidine compound, which is a liquid crystal compound useful as an electro-optical element, which utilizes the response of a ferroelectric smectic liquid crystal to an electric field.

Liquid crystals have been applied as various electro-optical elements and have been put to practical use for displays such as watches and calculators. Most of the liquid crystal display elements that have been put into practical use at present utilize the dielectric alignment effect of nematic liquid crystals or cholesteric liquid crystals.
However, when applied to a display element with a large number of expected pixels, there are problems in responsiveness, contrast due to lack of a drive margin, and viewing angle characteristics. Therefore, research and development of a MOS panel or a TFT panel in which a switching element is formed for each pixel is actively conducted.

U.S. Pat. No. 4,367,924 discloses a liquid crystal device according to a new display principle using a smectic phase which eliminates the drawbacks of the liquid crystal device.

Further, a liquid crystal compound showing a smectic C * phase or an H phase composed of optically active molecules generally has an electric dipole density P and is known to be ferroelectric. Since these chiral smectic liquid crystals have electric dipoles, they are more strongly affected by the electric field than by the dielectric anisotropy, and this acting force has the property that the polarity of P is parallel to the electric field. The direction of the molecule can be controlled by reversing the direction of the applied electric field. Then, by detecting the average change of the molecule in the long axis direction using two polarizing plates, it can be used as an electro-optical element.

The electro-optical element utilizing the response of the smectic C * phase or the H phase to the electric field has a spontaneous polarization and an action force exerted by the electric field which is 3 to 4 orders of magnitude larger than that due to the dielectric anisotropy. It has a superior high-speed response compared to, and can have a memory function by performing proper orientation control, and is expected to be applied to a high-speed optical shutter or a display with a large amount of display information. Is.

With respect to such a chiral smectic liquid crystal material having ferroelectricity, various compounds have been synthesized so far and their properties have been studied.

For example, in JP-A-61-93170, an optically active 2-
A (4-alkoxyphenyl) -5-alkylpyrimidine compound and an optically active 2- (4-substituted alkoxyphenyl) -5-alkylpyrimidine compound in JP-A-61-129169 are stable to moisture. And has been proposed as a compound exhibiting a chiral smectic phase in a wide temperature range.

However, the usable temperature range of the compound is also limited, and the properties are particularly insufficient on the low temperature side, which is not practically satisfactory.

The present inventors have conducted extensive studies as to a pyrimidine-based liquid crystal compound exhibiting a chiral smectic phase over a wider temperature range, and as a result, have a specific alkenoyloxy group having an asymmetric carbon atom, represented by the following general formula: It was found that the optically active phenylpyrimidine compound described above exhibits a chiral smectic phase particularly over a wide temperature range including a low temperature range, and has completed the present invention.

(In the formula, n represents 4 to 18, and * represents an asymmetric carbon atom.) The compound represented by the above general formula of the present invention can be produced by a general method for synthesizing a phenylpyrimidine compound. Is.

For example, a method of esterifying 5-n-alkyl-2- (4-hydroxyphenyl) pyrimidine with D-citronellic acid (3,7-dimethyl-6-octenoic acid) or esterifying 4-cyanophenol. After that, this can be produced by a method of pyrimidation by a conventional method.

The 5-alkyl-2- (4-hydroxyphenyl) pyrimidine compound is a general method for producing a pyrimidine compound, for example, 4-cyanophenol is benzyl etherified by a conventional method, and then 4-benziloxybenzamidine hydrochloride is used. And then reacted with n-alkylmalonic acid diester to give 2- (4-benzyloxyphenyl)
It can be produced by converting it to -4,6-dihydroxy-5-n-alkylpyrimidine, followed by chlorination and reduction.

The compound represented by the general formula of the present invention thus obtained can be used alone as a liquid crystal material, or can be used as a mixture with another liquid crystal compound.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Synthesis of 2- (4- (3,7-dimethyl-6-octenoyloxy) phenyl) -5-n-decylpyrimidine D-citronellic acid 0.47 g, 2- (4-hydroxyphenyl) -5- 0.78 g of n-decylpyrimidine and 0.55 g of dicyclohexylcarbodiimide were dissolved in 5 ml of dichloromethane. To this, 0.1 g of 4-pyrrolidinopyridine is added,
Stir at room temperature for 5 hours.

After removing the solvent, hexane was added, the generated dicyclohexylurea was filtered off, and the hexane was distilled off.

The residue was purified using a silica gel column with hexane / ether (85/15) as the developing solvent to give an optically active 2-
0.5 g of (4- (3,7-dimethyl-6-octenoyloxy) phenyl) -5-n-decylpyrimidine was obtained.

Infrared spectroscopy (cm ^-1 ) 2925 (s), 1760 (s), 1590 (m), 1430 (s), 12
00 (m), 800 (m) Specific optical rotation [α] _D = + 3.76 ° (25 ° C, C = 1, CHCl ₃ solution) This compound was subjected to orientation treatment by rubbing to a thickness of 2
It was poured into a glass transparent electrode cell of μm and heated to 90 ° C. to obtain an isotropic liquid.

When this liquid crystal cell was cooled while applying a rectangular wave of 15 V and 1 Hz under crossed Nicols, a clear switching operation was confirmed between 24.0 ° C and 1 ° C.

In addition, the following phase transitions were confirmed by observing the phase morphology with a polarization microscope.

The compound of the present invention exhibits a Sc ^* phase in a wide temperature range of 20 ° C. or higher including a low temperature of 1 ° C., and the compound has a Sc ^* phase ^.
It has Sx phase below the phase, and it was confirmed that the low temperature side maintains the smectic domain state up to -4 ° C. Therefore, it is clear that the above compounds are also suitable for obtaining a composition exhibiting a liquid crystal temperature at low temperatures.

Example 2 Synthesis of 2- (4- (3,7-dimethyl-6-octenoyloxy) phenyl) -5-n-octylpyrimidine Instead of 2- (4-hydroxyphenyl) -5-n-decylpyrimidine , 2- (4-hydroxyphenyl) -5
The title compound was synthesized by the same procedure as in Example 1 except that -n-octylpyrimidine was used.

Infrared spectroscopy (cm ^-1 ) 2925 (s), 1760 (s), 1590 (m), 1430 (s), 12
00 (m), 800 (m) Specific optical rotation [α] _D = + 3.72 ° (25 ° C, C = 1, CHCl ₃ solution) This compound was subjected to orientation treatment by rubbing to a thickness of 2
It was poured into a glass transparent electrode cell of μm and heated to 90 ° C. to obtain an isotropic liquid.

When this liquid crystal cell was cooled while applying a rectangular wave of 15 V and 1 Hz under orthogonal Nicols, a clear switching operation was confirmed between 12.5 ° C and -3.8 ° C.

In addition, the following phase transitions were confirmed by observing the phase morphology with a polarization microscope.

It was confirmed that the compound of the present invention exhibits a Sc ^* phase in a wide temperature range of 15 ° C. or higher including a low temperature of −3.8 ° C., and it is clear that it is suitable for obtaining a composition exhibiting a liquid crystal temperature at a low temperature. is there.

As described above, the compound of the present invention is a liquid crystal compound suitable for obtaining a composition exhibiting a liquid crystal temperature at a low temperature of room temperature or lower,
It is also useful as a blending agent suitable for obtaining a composition exhibiting a liquid crystal temperature at a low temperature below room temperature.

Claims (1)

[Claims] 1. An optically active pyrimidine compound represented by the following general formula. (In the formula, n represents 4 to 18, and * represents an asymmetric carbon atom.)