JPH0429975A - Novel ester compound and liquid crystal composition containing the same - Google Patents

Abstract

NEW MATERIAL:A compound of the formula (R1, R2 are 1-18C alkyl). EXAMPLE:2-(4-Hexyloxyphenyl) 5-(4-heptylcarbonyloxyphenyl)-pyrimidine. USE:A liquid crystal material capable of being converted into a stable thermotropic liquid crystal state and exhibiting a smectic C phase in a wide temperature range. Useful as a raw material for opto-electronic-related elements because a mixture with other liquid crystal materials can give good properties. PREPARATION:For example, an 2-(4-alkyloxyphenyl)-5-(4-hydroxyphenyl) pyrimidine synthesized from 4-hexyloxycyanobenzene as a starting raw material is subjected to a dehydration reaction in the presence of octanoic acid to prepare the example compound.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can take a stable thermotropic liquid crystal state, and can be used, for example, in displays such as liquid crystal televisions, optical printer heads, optical Fourier transform elements, light valves, etc. The present invention relates to a novel ester compound used in a liquid crystal material useful as a material for optoelectronics-related elements, and a liquid crystal composition containing this compound.

[Conventional technology]

Currently, liquid crystal materials are used as various display elements for watches, calculators, small televisions, etc., but these are mainly nematic liquid crystal materials. This nematic liquid crystal utilizes operation based on the weak interaction (ΔεE2/2) between the dielectric anisotropy Δε and the electric field E, so the response time to the electric field is several orders of magnitude.
It is slow at 0 msec.

For this reason, there are limits to its use in fields that require high-speed response, and the display capacity is also reaching its limit.
This is one of the obstacles to achieving larger screens.

By the way, in 1975, 4-(4-n-decyloxybenzylideneamino)cinnamic acid-2-methylbutyl ester (DOB) was synthesized by R.B. Meyer et al.
With the advent of ferroelectric liquid crystals, of which AMBC is a typical example, and surface-stabilized ferroelectric liquid crystal (SSFLC) cells that utilize bistable states in thin cells proposed by N., A., and C1ark et al. A liquid crystal cell with high-speed response on the μsec order and memory performance has become possible.

For this reason, many ferroelectric liquid crystal compounds have been synthesized to date.
Proposed. By the way, in order for these ferroelectric liquid crystal compounds to be used as liquid crystal materials, they must exhibit a xylsmectic C phase at least in a wide temperature range around room temperature, have large spontaneous polarization, and be chemically stable. is necessary. However, it is difficult to obtain a single compound that satisfies these requirements, and as with conventional nematic liquid crystal materials, there is a movement toward solving this problem by mixing several types of compounds. As this type of liquid crystal material, a type of phenylpyrimidine compound has been proposed (for example, Japanese Patent Application Laid-Open No. 63-235393).

However, the number of types of these liquid crystal compounds is still small, and a fully satisfactory ferroelectric liquid crystal composition has not yet been provided.

[Problems to be solved by the invention] The present invention solves the above-mentioned problems, and the purpose of the present invention is to:
A novel ester compound that is chemically stable, exhibits a smectic C phase in a wide temperature range near room temperature, and is useful as a material for a liquid crystal composition that can expand the temperature range of the smectic C phase of other liquid crystal compounds. It is about providing.

[Means to solve the problem]

(In the above formula, R1 and R2 are alkyl groups having 1 to 18 carbon atoms, and both may have a branch) and various liquid crystal compositions containing this compound. be.

R1 and R2 in the compound of the above formula of the present invention are selected from alkyl groups having 1 to 18 carbon atoms based on practical manufacturing considerations.

Representative examples of this compound and their physical and chemical properties are as follows.

(4-hexyloxyphenyl) (4-hexyloxyphenyl) pyrimidine IR (KBr, cm') + 2925. 174
0. 1610. 1580. 1440゜'H-NM
R (in CDCl2, 7MS standard, δ value ppm): 8.
95 (s.

2H), 8.44(d, 2H), 7.63(d
, 2H), 7.22(d, 2H), 7.03(
d, 21(), 4.06(t, 2H), 2.6
1 (t, 2H), 1.93-1.20 (m, 18
H), 0.93(t, 3H) 0.89(t,
3H) Mass+: 474 Luponyloxyphenyl)pyrimidine 1R (KBr, cm'): '2925. 17
40. 1610. 1580. 1440°'11-
NMR (CDC13, 7MS standard, δ value ppm):
8.95 (s.

2H), 8.44(d, 2H), 7.63(d
, 2H), 7.22 (d, 2H), 7.03 (d,
2H), 4.06(t, 2H), 2.61(t
, 2H), 1.93-1.20 (m, 14H),
1.06~0.83 (m, 6H) Mass”:
446 Sewing Machine IR (KBr, cm'): 2920. 175
0. 1605. 1580. 1435゜'H-NM
R (in CDCl2, 7MS standard, δ value ppm): 8.
96 (s, 2H), 8.45 (d, 2H), 7
．． 64 (d, 2H), 7.24 (d, 2H).

7.02 (d, 2H), 4.08 (t, 2H),
2.68 (m, IH), 1.91-1.29 (m
, 17H), 0.96(t, 3H), 0.93
(t,3H)Mass+: 460 The ester compound of the present invention shown in the above - formation can be synthesized by the following method.

Carphonic acid 2-(4-alkyloxyphenyl)-5
By dehydration condensation reaction with (4-hydroxyphenyl)pyrimidine, the carboxylic acid was converted into acid chloride using thionyl chloride, and then 2-(
By reacting with 4-alkyloxyphenyl)-5-(4hydroxyphenyl)pyrimidine, the above-forming 2-(4-alkyloxyphenyl)-5-(4-alkylcarbonyloxyphenyl)pyrimidine can be obtained. can.

This compound alone has a smectic C phase over a wide temperature range, but when mixed with other liquid crystal materials, it can expand the smectic C phase of the liquid crystal material, and is particularly useful for increasing the upper limit temperature of the smectic C phase. It is. for example,
When mixed with a pyrimidine base liquid crystal material, the transition temperature from smectic A phase to smectic C phase can be increased and the tilt angle can be increased without changing the phase series of the base liquid crystal. Of course, if this compound has an asymmetric carbon, it will itself become a ferroelectric liquid crystal, and the above-mentioned smectic C phase will all become a xylsmectic C phase. For example, if this compound is mixed with a pyrimidine-based base liquid crystal material, the above-mentioned effects can be obtained. This results in good effects such as increasing response speed. The mixing ratio of the ester compound of the present invention to the base liquid crystal material may be appropriately selected depending on the type of the base liquid crystal material, within a range that can exhibit the most effect.

(Example 1) Using 4-hexyloxycyanobenzene as a starting material, Jour
nal fuel Praktische Chemi
e) 2.5 g of 2-(4-hexyloxyphenyl)-5-(4-human-7xyphenyl)pyrimidine synthesized according to the method described in Vol. 7.18 mmol), octanoic acid 1.
After adding 200 mβ of methylene chloride to 24 g (8.6 mmol) and 105 mg (0.86 mmol) of 4-dimethylaminopyridine and stirring to make it homogeneous, N,N-
Dicyclohexylcarphodiimide 1.77g (8,58
mmol) was added. - After stirring overnight, the white crystals were filtered, the filtrate was concentrated and dried under reduced pressure to obtain white crystals. The crystals were purified by silica gel chromatography and recrystallized to yield 3.27 g of 2-(4hexyloxyphenyl)-5-(4-hebutylcarbonyloxyphenyl)pyrimidine having the above-mentioned physical and chemical properties. 96%).

Evaluation of liquid crystallinity The above compound was injected into a 2.5 μm thick cell made of glass with transparent electrodes coated with polyimide and subjected to rubbing treatment, and observed with a polarized light microscope while controlling the temperature on a hot stage. The temperature was changed at a rate of 2°C per minute.

As a result, during the cooling process, the isotropic liquid changed to a smectic A phase at 211°C, changed to a smectic C phase at 209°C, and became crystalline at 68°C. Also, in the heating process, 98°
C became a smectic C phase.

On the other hand, the above synthesized 2 When 10% of -(4hexyloxyphenyl)-5-(4-heptylcarbonyloxyphenyl)pyrimidine was added and the liquid crystallinity was evaluated in the same cell as above, the smectic A phase changed to the smectic C phase. temperature to 62°C, 1
The temperature rose by 5°C. These results confirm that the compound of the present invention has a smectic C phase over a wide temperature range, and that when this compound is mixed into a base liquid crystal material, the transition temperature from smectic A phase to smectic C phase can be increased. Ta.

(Example 2) 2-(4-butyloxyphenyl)-5-(4hydroxyphenyl)pyrimidine synthesized using 4-butyloxycyanobenzene as a starting material was converted into 2-(4-butyloxyphenyl)-5-(4hydroxyphenyl)pyrimidine in Example 1.
(4-Hexyloxyphenyl)-5-(4-hydroxyphenyl)pyrimidine was used in place of pyrimidine, but the same operations as in Example 1 were carried out, and 2-(4-butyl oxyphenyl)-5-(4-
Hebutylcarbonyloxyphenyl)pyrimidine was obtained.

Evaluation of liquid crystallinity The same method as in Example 1 was used.

As a result, in the heating process, the crystal changes to the smectic C phase at 112°C, and the smectic A phase changes to the smectic A phase at 205°C.
It became a nematic phase at 217°C and an isotropic liquid at 218°C.

(Example 3) In the same manner as in Example 1 except that (+)-2-methylhexanoic acid was used instead of octanoic acid, 2-(4- xyloxyphenyl)-5-(4-(1-methylpentylcarbonyloxy)phenyl)pyrimidine was obtained.

Evaluation of liquid crystallinity The same method as in Example 1 was used.

■ As a result, during the heating process, the crystal changes to an unidentified smectic phase at 82°C, and the xyl-smectic phase changes to an unidentified smectic phase at 97°C.
phase and became an isotropic liquid at 150°C.

In addition, when spontaneous polarization was measured using the triangular wave method, it was found to be 145°C.
26nC/cm2 at 30Vpp, 100Hz condition
showed that.

On the other hand, 2-(4-hexyloxyphenyl)5-(4
-(1-methylpentylcarbonyloxy)phenyl)
Liquid crystallinity was evaluated using the same cell as in Example 1 except that 15% pyrimidine was added and the cell thickness was 2.0 μm.
During the cooling process, the isotropic liquid changes to a cholesteric phase at 75°C, changes to a smectic A phase at 68°C, assumes a xylsmectic C phase at 65°C, and exhibits spontaneous polarization 2, LnC/cm2, and slope at 25°C. Corner 24° response time 150μs
ec was shown.

(Effects of the Invention) The novel ester compound of the present invention can take a stable thamotropic liquid crystal state and has smectic C in a wide temperature range.
phase and also by mixing with other liquid crystal materials,
It has excellent properties as a material for optoelectronics-related elements, such as being able to impart good properties as a liquid crystal.

Therefore, the present invention can be said to be a liquid crystal material that is useful as a material for optoelectronic-related elements that utilize liquid crystals and electrochemistry, such as displays such as liquid crystal televisions, optical printer heads, optical Fourier transform elements, and light valves.

Claims (1)

[Claims] 1. The following general formula, ▲ Numerical formula, chemical formula, table, etc.▼ (In the above formula, R_1 and R_2 are alkyl groups having 1 to 18 carbon atoms, even if both have branches A novel ester compound characterized by being represented by 2. A liquid crystal composition containing the compound according to claim 1.