JPS59184166A - Pyrimidine - Google Patents

Abstract

NEW MATERIAL:5-Alkyl-2-(4'-alkylphenyl)pyrimidine of formula I (R1, R2 are 1- 10C alkyl). EXAMPLE:5-Propyl-2-(4'-benzylphenyl)pyrimidine. USE:A component for liquid crystal compositions: it has a large anisotropy in refractive index in comparison with its low viscosity, further high stability and compatibility. The addition of the compound increases response properties, contrast, sharpness and lowers the viscosity of the composition and the threshold voltage. PREPARATION:The cyclization reaction between 4-alkylphenylamidine hydrochloride of formula II and alkylmalonic diethyl ester of formula III is carried out in the presence of a catalyst of sodium methoxide to give a compound of formula IV, which is treated with POCl3 to effect chlorination into a compound of formula V. Then, the compound is reduced with hydrogen in the presence of a Pt/C catalyst to give the compound of formula I .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel organic compound, and more particularly to a novel liquid crystal compound useful as a component of a liquid crystal material.

As is well known, liquid crystal materials can be used in display elements (so-called TN cells) that use nematic liquid crystals with twisted liquid crystal alignment, as well as display elements that apply the guest-host effect of liquid crystal materials or liquid crystal mixtures containing appropriate dyes, and are widely used as DB-type display elements that utilize the dynamic scattering effect of liquid crystals, display elements that utilize cholesteric-nematic phase transition, and DAP-type display elements that utilize the electric field controlled birefringence effect of liquid crystals. The materials encapsulated in these liquid crystal display elements cannot be used practically due to their various characteristics, such as liquid crystal temperature range, operating voltage, response performance, etc., if they are made of a single compound. ing.

The present invention provides a compound useful as a component constituting such a practical, excellent and stable liquid crystal composition. That is, the present invention provides a compound (1) of the present invention having the general formula (in the above formula, R□ and R2 represent an alkyl group having 1 to 1 o carbon atoms), which has a low viscosity and an anisotropy of refractive index. It is a compound with large properties and excellent stability.
Because of their excellent compatibility, they have the effect of improving the responsiveness, contrast, and sharpness of liquid crystal compositions to which the compounds of the present invention are added, as well as reducing viscosity and threshold voltage.

The compound of the present invention can be synthesized according to the following reaction formula.

(In the above formula, R□ and R2 represent an alkyl group having 1 to 1 o carbon atoms.) First, the 4-alkylphenylamidine hydrochloride of compound (It) and the alkylmalonic acid diethyl ester of compound (2) were combined with sodium methoxide. A cyclization reaction is carried out in the presence of 2,5-substituted-4,6-cyhydroxypyrimidine derivative of compound MJ (Iv).

Next, this compound (1) is chlorinated using phosphorus oxychloride to obtain a 2,5-substituted-4,6-cyclopyrimidine 7 derivative of compound (V). Last K, this compound (
V) The target compound (1) can be obtained by reducing e-palladium-supported carbon with hydrogen using a catalyst.

Hereinafter, the compounds of the present invention will be explained in more detail with reference to Examples.

In each example, the crystal phase is abbreviated as 01, the nematic phase is abbreviated as N, and the transparent phase is abbreviated as N to indicate the transition point.

Example 1 (Synthesis of 5-7'ropyru-2-L (4'-pentylphenyl)pyrimidine) (1st stage) Metallic sodium 20 t (o, s 7 atom) t-
Add 400 mg of anhydrous methanol to obtain sodium methoxide, cool on ice, stir, and add 50 f of 4-pentylphenylamidine hydrochloride (II) (0.22 mo
/) and U n -7'rovylmalonic acid diethyl ester (t) 45F (0.22 moJ?) were added, and the mixture was refluxed with stirring for 8 hours. This was cooled on ice, 600A of 20% hydrochloric acid was added, the precipitate was filtered, the crystals were washed with water and acetone, and dried to give 5-furopyl-2-(4'-pentylphenyl)-4.
, 6-cyhydroxypyrimidine Qv) 55f (yield 83
%) t-4.

(Second stage) 5-propyl-2-, (4'-pentylphenyl)-4,6-cyhydroxybilimine (Jl) obtained in the first stage
55 f (0,18 mol) of IJ oxychloride 73
After adding 5.0- and N,N-diethylaniline 5o- and refluxing for 20 hours with stirring, excess phosphorus oxychloride was distilled off, and 1000 d of a 10% by weight aqueous sodium hydroxide solution was cooled on ice while still hot. and add 400 g of toluene.
After washing the toluene layer with 20-dihydrochloric acid and water, the toluene was distilled off, recrystallized with a mixed solvent of n-heptane-ethanol, and dried. -(4'-pentylphenyl)-4,6-dichloropyrimidine (V) 49t (yield 80%).

(melting point 38°C) was obtained.

(Third stage) 5-propyl-2-'(4'-pentylphenyl)-4,6-dichloropyrimidine (V) 41 obtained in the second stage
t(0,12mob) with ignesium oxide 2ot,
Carbon 0.41F carrying 5% by weight of palladium, 500 m/m of ethanol, and 36 m/m of water were added, and hydrogen gas was absorbed at room temperature until it was saturated. The reaction product was filtered, the residue was washed with toluene, the toluene layer and p liquid were distilled off, dissolved in toluene 1001Rt, washed with 10qb aqueous sodium hydroxide solution, and then washed with water until neutral, and then the toluene was distilled off. The final target product, 5-propyl-2(4/-pentylphenyl)pyrimidine (1) 26F (yield 79%, C-
1 point 33°5°C.

N-1 point 17°C (extrapolated value)) was obtained. Moreover, the elemental analysis values of this compound are in good agreement with the calculated values as shown below.

Example 2 0 5-Butyl-2-(4/-pentylphenyl)pyrimidine was synthesized in the same manner as in Example 1. The compound is C
-1 point was 3°C, N-point was 105°C (extrapolated value).

Example 3 (Usage example 1) The N-1 point of liquid crystal composition A is 71.9°C.

The viscosity at 20°C is 27.9 cp, and the electrical anisotropy Δε is 11.7 (ε, +=16.2.g = 4.5), which is sealed in a TN cell with a cell thickness of 10 μm. However, the threshold voltage is 1. s4v, the saturation voltage is 2.50V, and the refractive index anisotropy Δn is 0.140 (ne = 1.63
2, n□, =1.492).

Compound 5-7 of the present invention is added to 70 parts by weight of the liquid crystal composition A.
The N-1 point of the liquid crystal composition to which 30 parts of Lobi-2-(4'-pentylphenyl)pyrimidine was added was 55.5.
℃, - decreased to 24゜7cp, and △ε was 9.6 (g,
=13.8, g=4.2) I The threshold voltage is 1.68V, the saturation voltage is 2.25V,! : Decrease, Δn was 0.134.

Example 4 (Use Example 2) To 70 parts by weight of the same liquid crystal composition A used in Example 3, 30 parts by weight of the compound 5-butyl-2-(4'-pentylphenyl)pyrimidine'f of the present invention was added. The N-1 point of the liquid crystal composition is 93.5°C.

η,. is 26. Ocp decreases and △ε is 9.3 (ε, = 1
3.6°εl=4.3)i The threshold voltage was 1.66V, the saturation voltage decreased to L88V, and Δn was 0.128T.

that's all

Claims (2)

[Claims] (1) 5-alkyl-2-(4'-alkylphenyl)pyrimidine represented by the general formula (in the above formula, R□ and R2 represent an alkyl group having 1 to 10 carbon atoms). (2) Contains at least one type of 5-alkyl-2-(4/-alkylphenyl)pyrimidine represented by the general formula (in the above formula, R□ and R2 represent an alkyl group having 1 to 1 o carbon atoms) A liquid crystal composition characterized by: