JPH02200677A - Ester derivative of allylbiphenylcarboxylic acid with fluoropyrimidinylphenols - Google Patents

Abstract

NEW MATERIAL:A compound expressed by formula I (R<1> and R<2> each are straight-chain or branched 1-15C alkyl or alkoxy). EXAMPLE:2-Fluoro-4-(5-propyl-2-pyrimidinyl)phenyl 3-allyl-4-pentyloxybiphenyl-4'- carboxylate. USE:Useful as a component of liquid crystal compositions, excellent in compatibility with liquid crystal compounds, such as ester-based, Schiff base-based or biphenyl-based liquid crystal compound, capable of increasing N-1 point by addition thereof in a small amount to a liquid crystal composition and further increasing a value of K3/K1 and especially suitable as super twisted nematic(STN) type display elements. PREPARATION:For example, as shown in the reaction formula, ethyl 4- allyloxybiphenyl-4'-carboxylate as a raw material is passed through several steps to afford the compound expressed by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ester derivative of fluoropyrimidinylphenols of allylbiphenylcarboxylic acid and a liquid crystal composition containing the compound as an active ingredient.

[Prior Art] Display elements using liquid crystals are widely used in watches, calculators, and the like.

These liquid crystal display elements utilize optical anisotropy and birth anisotropy of liquid crystal materials. The liquid crystal phase includes a nematic liquid crystal phase, a smectic liquid crystal phase, and a cholesteric liquid crystal phase, and among these, those using nematic liquid crystal are most widely put into practical use.

These display elements include TN (twisted nematic type), DS (dynamic scattering) type, guest-host type, DAP type, etc. corresponding to the electro-optic effect applied to liquid crystal displays. It is desirable that the liquid crystal substances used in each case exhibit a liquid crystal phase over as wide a natural temperature range as possible.

At present, there is no single liquid crystal material that satisfies these conditions, and several types of liquid crystal materials or a mixture of non-liquid crystal materials have been put into practical use.

These substances are required to be stable against moisture, light, heat, air, and the like.

[Problems to be Solved by the Invention] In recent years, multi-drive display of display elements has been desired, but since the display area is inferior in the conventional TN type system, a new series of 5T type systems has been developed.
N (super twist) type display element is M, 5chadt
[Appl, Phys, Lett, 50,236
(1987)] and has excellent display quality even in multi-drive display.

When we consider an arrangement of liquid crystal molecules as a continuum material, we can consider that the continuum material is distorted when the arrangement of liquid crystal molecules changes depending on the location. This strain includes splay and twist (T+v4st)
There are three basic types: , bend. The liquid crystal elastic modulus is determined from the threshold value when a magnetic field or electric field is applied to uniformly oriented cells. The elastic moduli of spreading, twisting, and bending are respectively 1, K2, and K3. Regarding the birth rate of liquid crystal, when the electric rate parallel to the axis direction is cll and the perpendicular direction is 6 earth, there are two cases: △ε=611−〇 earth〉0 and 〈O, and the former is expressed as p type liquid crystal, and the latter is called n-type liquid crystal.

The N-1 point refers to the temperature at which a nematic liquid crystal becomes an isotropic liquid, and a liquid crystal with a high N-1 point can be used in a liquid crystal element even at high temperatures. A liquid crystal that exhibits a nematic phase from low to high temperatures is ideal.

The desired liquid crystal properties for the STN system are a large value of 3/Kl and a small value of Δε/C. i.e. 3/K
When l is large and Δε/ε is small, multiplex characteristics become better and multi-digit driving becomes possible. Conversely, the smaller 3/Kl and the larger Δε/ε, the less bisteresis occurs, but the multiplex characteristics are poor.

In this way, the STN system is characterized by its ability to drive in multiple digits, and the emergence of liquid crystal compounds that can drive in even more digits is desired (M, 5chadt, F, Leenhouts, 5o
Society for Information Disp
lay, International Symposium
Digest of Technica
I Paters Vol, X VIIINew
0rleans,Louisiana,May
12-14. (1987) 372-375).

The present invention is a compound with a relatively large K3/Kl and excellent compatibility, which is suitable for multi-drive display using an STN type display element, and which can be blended with other liquid crystal compositions to achieve N-1.
The object of the present invention is to provide a novel compound for liquid crystals that can increase the point.

A further object of the present invention is to provide a liquid crystal composition containing the compound.

[Means for Solving the Problems] The present invention is an ester derivative of fluoropyrimidinylphenols of allyl biphenylcarboxylic acid represented by the following general formula [1].

In formula (1), R1 and R2 each represent a straight or branched alkyl group or alkoxy group having 1 to 15 carbon atoms. ) The present invention also provides a liquid crystal composition containing at least one type of the composition.

Compounds other than the fluoropyrimidinylphenol ester conductor of allyl biphenylcarboxylic acid of the present invention that can be used as components of the liquid crystal composition include:
Examples include ester-based, Schiff base-based, biphenyl-based, phenylcyclohexane-based, and heterocyclic-based liquid crystal compounds.

The ester derivative of fluorobyrimidinylphenols of arylbiphenylcarboxylic acid of the present invention can be produced, for example, by the reaction of the following formula.

Boiling and refluxing to obtain 3-allyl-4-hydroxybiphenyl-4°-carboxylic acid ethyl ester, followed by DMF
3-allyl-4-
alkoxybiphenyl-4°-carboxylic acid ethyl ester, then hydrolyzed using potassium hydroxide,
3-allyl-4-alkoxybiphenyl-4°-carboxylic acid.

This carboxylic acid is converted into an acid chloride using thionyl chloride, and this is reacted with 2-fluoro-4-(5-alkyl-2-pyrimidinyl)phenol in the presence of pyridine to form the desired fluorophenols of allyl biphenylcarboxylic acid. Ester derivatives were produced.

(R1 and R2 in the above formula are the same as above.) That is, 4-allyloxybiphenyl-4°-carboxylic acid ethyl ester in N,N-diethylaniline [Example] The present invention will be described below by way of example. will be described in more detail, but the present invention is not limited to this example in any way.

In the examples, the C-N point indicates the transition temperature from the crystalline phase to the nematic phase. Further, as mentioned above, the N-1 point indicates the transition temperature from a nematic phase to an isotropic liquid.

Regarding the refractive index, the refractive index parallel to the axial direction of the liquid crystal is n
If, when the perpendicular direction is on n, △n = n If
-n>0 The value of Δn represents the anisotropy of the refractive index, and the magnitude of Δn is important when considering the response speed. In order to produce the same optical effect, if △n is large, the thickness of the liquid crystal cell used can be reduced, the electric field strength can be increased even with the same voltage applied, and the response speed of the liquid crystal cell operation can be increased. . However, when Δn is small, visual characteristics are good.

In this example, the measurement of C-N point and N-I point was carried out using Mettler FP.
-80 and FP-82 were attached to a polarizing microscope and measured.

Δε was measured with an LCR meter model 4274A manufactured by Yokogawa-Hurett-Packart, and Δn was measured with a microlfractometer manufactured by Leitz-Wetzler.

In addition, as mentioned above, Δε=611−ε represents the anisotropy of the electrophilicity of the liquid crystal, and the threshold voltage (vth) in the operation of the TN display method is expressed by and is inversely proportional to J]. do. Therefore, when viewed as a timepiece display, low voltage driving is an important factor in terms of power consumption, so a liquid crystal with a large Δε is desirable in order to lower the threshold voltage.

Example 1 Preparation of 3-allyl-4-pentyloxybiphenyl-4°-carboxylic acid 2-fluoro-4-(5-propyl-2-pyrimidinyl)phenyl ester 4-allyloxybiphenyl-4′-carboxylic acid ethyl ester 2a, 2g (0-1 mol) was dissolved in N,N-diethylaniline 100a+9 and refluxed under nitrogen atmosphere for 8 hours. After cooling, the reaction solution was added to 500 mJ2 of 6N hydrochloric acid. - After standing overnight, the deposited precipitate was filtered off, thoroughly washed with a small amount of water, and thoroughly dried under reduced pressure. This one is 3-
Allyl-4-hydroxybiphenyl-4-carboxylic acid ethyl ester.

This product was dissolved in 300 mA of DMF, and 22.5 g (0.15 mol) of pentyl bromide was added at room temperature while stirring well with 70 g of anhydrous sodium carbonate. Then, it was heated at 100° C. for 6 hours using a mantle heater. After the reaction was completed, a large amount of water was added and the mixture was extracted with chloroform. The chloroform layer was washed with condensate water washed with 2N sodium hydroxide. Chloroform was distilled off, and then the solvent was completely removed under reduced pressure.

The residual extract was added to a mixture of 200 mft of ethanol and 84 g of potassium hydroxide dissolved in 100 mIt of water. The reaction is then boiled and refluxed on a mantle heater for 5 minutes.
Time went. Thereafter, the reaction solution was added to dilute hydrochloric acid, and the precipitate deposited was filtered. After washing thoroughly with water, I dried it. This is 3-allyl-4-pentyloxybiphenyl-4°
- It is a carboxylic acid.

3.2 g (0.01 mol) of this product was boiled and refluxed with excess thionyl chloride for 5 hours, and then thionyl chloride was distilled off under reduced pressure.

The oil that remains is the acid chloride. Separately 2-fluoro-
4-(5-propyl-2-pyrimidinyl)phenol 2
．． 8 g (0,012 mol) was dissolved in 20 all of pyridine, and to this solution was added the previously prepared acid chloride to 10 of toluene.
0ml was added with vigorous stirring.

After standing overnight, the reaction product was poured into 100 mjl, the toluene layer was separated and washed with 2N sodium hydroxide, and then the toluene layer was washed with water until it became neutral.

Thereafter, the toluene layer was dried over anhydrous sodium sulfate, and the toluene was distilled off under reduced pressure. The remaining solid was recrystallized from ethanol to produce the desired compound. The C-N point of the obtained compound is 101.5-102.4°C, N-1
The temperature was 200.0°C, and the yield was 2.2 g (yield 41%).

The same root is 3-allyl-4-pentyloxybiphenyl-4-carboxylic acid 2-fluoro-4-(5-hexyl-
The C-N point of 2-pyrimidinyl) phenyl ester is 78
．． 5-79.8°C, N-I point was 185.2°C.

Example 2 As a liquid crystal compound other than the liquid crystal compound of the present invention, trans-
4-Propyl-(4″-cyanophenyl)cyclohexane 24% by weight trans-4-pentyl-(4°-cyanophenyl)cyclohexane
36% by weight trans-4-hebutyl-(4°-cyanophenyl)cyclohexane
25% by weight trans-4-pentyl(4
゛-cyanobiphenyl)cyclohexane
The N-1 point of liquid crystal composition (A) (7) of 15% by weight is 72. Ot:, Δε is +11.0. Viscosity at 20°C is 28 cp, Δn is 0.140. K3/K1
is 1.82.

A liquid crystal cell was prepared in which substrates coated with silicon oxide and having transparent electrodes of rubbed tin oxide were assembled to face each other, and the distance between the electrodes was 10 μm.

When the above liquid crystal composition (A) was sealed and its characteristics were measured at 20°C, the threshold voltage was 1.82V.

To 90 parts of this liquid crystal composition (A), 3-
The N-
One point is 79°C, Δε is 10.8, Δn is 0.137, and the viscosity is 38 cp. K3/Kl is 1.94, which is suitable for STN.

Note that retardation, which is generally expressed as R = △nXd (d is electrode open circuit III), is a quantity that indicates the optical path difference between ordinary light and extraordinary light, and transmittance is expressed with transmittance on the vertical axis and R on the horizontal axis. There is a first minimum point at ΔnXd=0.48 and a second minimum point at ΔnXd=0.15. These two points are generally used; the first has good visual characteristics but is difficult to control d, and the second is easy. However, a material with a large Δn has a high viscosity η, and a material with a small Δn has a low η, so even if it is difficult to control d, the first minimum point is improved.

[Effects of the Invention] The ester conductor of fluoropyrimidinylphenols of allyl biphenylcarboxylic acid of the present invention is a novel compound and is a compound useful for use in liquid crystal displays.

Furthermore, the compound of the present invention has good compatibility with many other liquid crystal compounds, such as ester-based, Schiff base-based, biphenyl-based, phenylcyclohexane-based, and heterocyclic-based liquid crystal compounds. By adding small amounts to the composition, its N-I point can be raised.

Moreover, when the compound of the present invention is added to a liquid crystal composition, 3/3
Since the value of Kl can be increased, it is a suitable metal compound for liquid crystal compositions for STN type display elements.

Claims (1)

[Claims] 1. An ester derivative of fluoropyrimidinylphenols of allyl biphenylcarboxylic acid represented by the following general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...[I] (However, in the formula [I], R^1 and R^2 are each a linear or branched alkyl group or alkoxy group having 1 to 15 carbon atoms. ) 2. A liquid crystal composition containing at least one ester derivative of fluoropyrimidinylphenols of allyl biphenylcarboxylic acid according to claim 1.