JPH06192198A - Liquid crystal compound - Google Patents

Abstract

PURPOSE:To obtain the novel chiral smectic liquid crystal consisting of an acid amide compound produced from a p-aminobenzoic acid ester and a biphenylcarboxylic acid, large in spontaneous polarization, high in electric field responsibility, and useful for liquid crystal elements, etc. CONSTITUTION:p-Nitrobenzoic acid chloride is reacted with an optically active 2-alkanol, and the nitro group of the reactio product is reduced in the presence of palladium-carbon catalyst in a hydrogen gas atmosphere to produce an optically active 4-aminobenzoic acid ester of formula I (R<2> is 3-14C alkyl; * is optically active center)[e.g. (R)-(-)-4-aminobenzoic acid 2-octyl ester]. The compound of formula I is reacted with a 4-alkyloxybiphenyl-4'-carboxylic acid chloride of formula II (R<1> is 4-16C alkyl) to obtain the objective novel liquid crystal compound of formula III in which the amide group as a polar group is introduced in the liquid crystal skeleton to enlarge spontaneous polarization and enhance electric field responsibility.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a chiral smectic liquid crystal compound having an amide group as a polar group, and the liquid crystal compound is a liquid crystal used in a display element or an electro-optical element utilizing the response to an electric field. It relates to compounds.

[0002]

2. Description of the Related Art In recent years, TN type liquid crystal display elements have been widely used for display systems such as watches and calculators. The liquid crystal material used in this display system is a nematic or cholesteric liquid crystal, and the driving force that moves the molecules with respect to the electric field is essentially based on the dielectric anisotropy of the liquid crystal molecules, so the response speed is slow. In addition, it has basic problems such as difficulty in high-multiplex drive. Recently, smectic liquid crystals having a possibility of overcoming these problems, particularly chiral smectic liquid crystals exhibiting ferroelectricity, have been actively studied. The reason was Clar in 1980.
According to K. and Lagawall et al., since ferroelectric liquid crystals have spontaneous polarization, (1) fast microsecond response, (2) bistable memory characteristics, (3) existence of write threshold voltage, etc. The extremely important characteristics of the display device have been reported. Furthermore, due to its excellent viewing angle characteristics, it has come to receive a great deal of attention as a new display display, and its application to large-capacity displays and memory-type displays has been tried. In such a method using the electric field response optical effect of liquid crystal, it is said that it is preferable to introduce a polar group in order to enhance the response of the liquid crystal. In particular, it is known that the response speed of a ferroelectric liquid crystal is proportional to the spontaneous polarization, and it is desired to increase the spontaneous polarization in order to increase the speed. From such a point of view, up to now, a ferroelectric liquid crystal material having an azomethine, ether or ester group as a polar group in the molecule has been developed, but the chemical stability of the liquid crystal compound is insufficient. In addition, there is a problem that a satisfactory spontaneous polarization value cannot be obtained, and development of a new liquid crystal material is strongly demanded.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and by introducing an amide bond as a polar group into a liquid crystal skeleton, spontaneous polarization is increased and electric field response is improved. It is intended to provide a liquid crystal composition.

[0004]

The present invention has the general formula

[Chemical 2] (Wherein R ¹ is an alkyl group having 4 to 16 carbon atoms, R ² is an alkyl group having 3 to 14 carbon atoms, and * represents an optically active center). Liquid crystal compound.

An example of a general method for synthesizing the compound of the present invention is as follows.

[Chemical 3]

In the method for producing the compound of the present invention, first, p-nitrobenzoic acid-2-alkyl ester (1) is produced by reacting p-nitrobenzoic acid chloride with an optically active 2-alkanol. Then, the nitro group of (1) is replaced with (2)
To the amino group of. The catalyst used in this step is
Under a hydrogen atmosphere, the palladium - carbon catalyst, PtO ₂ -
RhO ₂ catalyst, Raney nickel catalyst, CuCr ₂ O ₄ catalyst and the like are suitable, but they can also be reduced to amino groups by zinc-hydrochloric acid or stannous chloride-hydrochloric acid. The target compound (4) can be produced by reacting the compound (2) with 4-alkyloxybiphenyl-4′-carboxylic acid chloride (3).

[0007]

EXAMPLES The present invention will be described below with reference to examples.
It is not limited to this. Example 1

[Chemical 4] Synthesis of (R)-(-)-N-4- (2-octyloxycarbonyl) phenyl-4-4'-n-octyloxybiphenylcarboxamide

[Chemical 5] Synthesis of (R)-(−)-4-aminobenzoic acid-2-octyl ester (R)-(−)-2-octanol [α] D ²⁰ = + 2
5.59 (C = 0.9951, C = in CHCl ₃₎ 0.
A solution prepared by dissolving 66 g, triethylamine 0.60 g and dimethylaminopyridine 0.12 g in methylene chloride 8 ml was added dropwise to a solution of p-nitrobenzoic acid chloride 1.12 g in methylene chloride 12 ml under ice cooling while gradually stirring. . After returning to room temperature and stirring for 12 hours, the reaction solution was poured into ice water and extracted with methylene chloride, and the methylene chloride layer was washed with diluted hydrochloric acid, water, 1N sodium carbonate and water in this order, and anhydrous magnesium sulfate was used. After dehydration, the solvent was distilled off under reduced pressure to obtain a crude product. This crude product was separated and purified by silica gel chromatography to obtain (R)-(-)-
4-Nitrobenzoic acid-2-octyl ester 1.34 g
Got Dissolve this in ethanol and add 5% Pd-C
Is added and the reduction reaction is performed in an H ₂ atmosphere to obtain the target product (R).
1.6 g of 2-(-)-4-aminobenzoic acid 2-octyl ester was obtained.

[Chemical 6] Synthesis of (R)-(-)-N-4- (2-octyloxycarbonyl) phenyl-4-4'-n-octyloxybiphenylcarboxamide 4-4'-n-octyloxybiphenylcarboxylic acid chloride 0.42 g 5 ml of methylene chloride solution containing
A solution prepared by dissolving 0.24 g of (R)-(-)-4-aminobenzoic acid 2-octyl ester obtained in [1], 0.12 g of triethylamine and 0.02 g of dimethylaminopyridine in 5 ml of methylene chloride was iced. It was gradually added dropwise under cooling. After returning to room temperature and stirring for 12 hours, the reaction mixture was poured into ice water and extracted with methylene chloride, and the organic layer was washed with diluted hydrochloric acid, water, 1N sodium carbonate and water in this order, and dehydrated with anhydrous magnesium sulfate. After that, the solvent was distilled off under reduced pressure to obtain a crude product. This crude product was treated by silica gel column chromatography and recrystallized from ethanol to give the desired product (R)-(-).
0.32 g of -N-4- (2-octyloxycarbonyl) phenyl 4-4'-octyloxybiphenylcarboxamide was obtained. The above compound exhibited liquid crystallinity, and the following phase transition temperature was confirmed by a polarization microscope using a hot stage.

[Table 1] Example 2 (R)-(−)-N-4- (2-octyloxycarbonyl) phenyl 4-4′-decyloxybiphenylcarboxamide

[Chemical 7] The target compound was prepared in the same manner by using 4,4'-decyloxybiphenylcarboxylic acid chloride instead of 4,4'-octyloxybiphenylcarboxylic acid chloride of Example 1. The above compound exhibited liquid crystallinity, and the following phase transition temperature was confirmed by a polarization microscope using a hot stage.

[Table 2]

[0008]

The optically active compound of the present invention can be an important and useful material as a ferroelectric liquid crystal compound. The liquid crystal compound and the liquid crystal composition of the present invention have good responsiveness to an applied electric field as a ferroelectric liquid crystal, and can be applied to liquid crystal display devices, liquid crystal optical shutters, and nonlinear optical functional materials. INDUSTRIAL APPLICABILITY The liquid crystal compound and the liquid crystal composition of the present invention exhibit an electroclinic effect in which a smectic A phase shows an optical response to an applied electric field, and can be applied to a light valve and an electro-optical shutter.

Front Page Continuation (72) Inventor Takashi Hagiwara 3-5 Kasumigaseki, Chiyoda-ku, Tokyo Awa Shell Oil Co., Ltd. Petroleum Corporation (72) Inventor Masaaki Kakimoto 61-9-3-504 Ikebukuro, Naka-ku, Yokohama-shi, Kanagawa (72) Inventor Yoshio Imai 1-9-2-303 Nakamagome, Ota-ku, Tokyo

Claims (1)

[Claims] 1. A general formula: (Wherein R ¹ is an alkyl group having 4 to 16 carbon atoms, R ² is an alkyl group having 3 to 14 carbon atoms, and * represents an optically active center). Liquid crystal compound that does.