JPS60132978A - 2-substituted-6-(trans-5-alkyl-1,3-dioxan-2-yl)naphthalene - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R1 is 1-10C alkyl; R2 is 1-10C alkyl or alkoxy). EXAMPLE:2-Propoxy-6-(trans-5-butyl-1,3-dioxan-2-yl)naphthalene. USE:A liquid crystal composition. When a small amount of the compound is added to a conventional liquid crystal composition, the upper limit of the working temperature range of the liquid crystal display element containing said liquid crystal composition can be raised, and the driving voltage of the element can be lowered. PREPARATION:The compound of formula I can be produced by reacting the 2- alkyl-1,3-propanediol of formula II with the 6-substituted-2-naphthaldehyde of formula III in toluene in the presence of p-toluenesulfonic acid as the catalyst, and separating and purifying the resultant 5-alkyl-2-(6-substituted-2-naphthyl)-1,3- dioxane of formula IV by recrystallization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a versatile liquid crystal compound and a liquid crystal composition containing the compound.

Display elements using liquid crystals are widely used in watches, calculators, etc. These liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials, and the liquid crystal phases include nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase. Most widely put into practical use. i.e. they have TN
(Twisted Nematic) type, D8 (Dynamic Scattering) type, Guest-Host type, DAP plastic type, etc., and the properties required of the liquid crystal materials used for each type are different. It is desirable that the liquid crystal materials used in these display devices exhibit a liquid crystal phase over as wide a natural temperature range as possible, and at present there is no single material that satisfies such conditions; several types of liquid crystal materials are currently available. It is put into practical use by mixing a substance or a non-liquid crystal material. These substances are required to be stable against moisture, light, heat, air, etc., and furthermore, it is desirable that the threshold voltage and saturation voltage required to drive the display element be as low as possible.

The object of the present invention is to provide a novel liquid crystal compound suitable for this noodle use.

That is, the present invention relates to the general formula (in the above formula, lt1 is an alkyl group having 1' to 10 carbon atoms, R
2 represents an alkyl group or an alkoxy group having 1 to 10 carbon atoms), 2-tZ-substituted-6-(trans-5-
A liquid crystal composition containing argyl-1,3-dioxan-2-yl)naphthalene and the compound.

The compound of the present invention is generally used for liquid crystal compounds,
That is, by adding a small amount of 1 degree to a liquid crystal composition made by mixing ester-based, Schiff base-based, biphenyl-based, phenylcyclohexane-based, heterocyclic, etc. liquid crystal compounds, the liquid crystal □ composition can be utilized [, It would be possible to raise the upper limit of the operating temperature range of liquid crystal display elements and lower the driving voltage.

The compounds of the present invention are produced by the method described below. ″
゛2-alkyl-1,3-propanediol and 6'-
I--alkyl-2-(6-substituted-2-naphthyl)-1,3-dioxane was prepared by reacting 2-naphthaldehyde in toluene with P-)luenesulfonic acid as a catalyst. ;(It is done. This □ thing □ is trans-
It is a cis mixture, and the desired 2-substituted-6-(trans-5-alkyl-1,3-dioxan-2-yl)naphthalene can be produced by separating and purifying it using a PJ crystal.

The chemical formula for the above is as follows.

(In the formula, 锇 and 1L2 are the same as above.) The compounds of the present invention will be explained in more detail with reference to Examples below.

Example 1 [2-propoxy-6-(trans-5-butyl-1,
Production of 3-dioxan-2-yl)naphthalene] 2-Butyl-1,3-propanediol 3.63y(2
7,5@mol,) and 5.86 g (27,5; mol) of 6-broboxy-2-naphthaldehyde were placed in a flask and dissolved in 80rnt of toluene. Next, about 20 μm of p-toluenesulfonic acid was processed and heated under reflux for 3 hours while stirring. The reaction mixture cooled to room temperature is
It was washed with an aOH aqueous solution and then with water, and the toluene was distilled off under reduced pressure to obtain crystals.

Next, the desired 2-propoxy 6
-(trans-5-butyl-1,3-dioxane-2-
1.03 g (3.1 mmol) of naphthalene (yield: 113%). This liquid crystal was a monotropic liquid crystal and had a melting point of 100.3.

Example 2' □ Practical Example 2-Hebutyl-1,3-propanediol/1.
and 6-pentyloxy-2-naphthaldehyde were used as raw materials, but the procedure was as in Example 1.
2-pentyloxy-6-(trans-5-hebutyl-
1,3-dioxan-2-yl)naphthalene was produced. This material exhibits a liquid crystal phase, with a crystalline-smectic phase transition point (-8 point) of 64.7-65.21T and a smectic-nematic phase transition point (8-N point) of 81.4-81T.
．． 5 tons? , the N-N point was 102.5-102.67:'.

Example 3 (Application example) The N-N point of the liquid crystal mixture (A) having the composition is 52. IC 1. A liquid crystal cell was prepared by assembling substrates having transparent tin oxide electrodes coated with silicon oxide and subjected to rubbing treatment and having an electrode distance of 1 llir of 1011 m, and using the above liquid crystal mixture (A ) and 20
When we measured its characteristics with C, we found that the desired voltage (hereinafter referred to as Vt
h) is 1.54V, and the color sum voltage (hereinafter Vsat) is 1.54V.
) was 2.13V.

This crystalline mixture (A) 85-weight 1.1 was mixed with 2-bentyl-6-(trans-5-
The N-N point of the composition containing 15% by weight of hebutyl-1,3-dioxan-2-yl)naphthalene increased to 593C. Furthermore, regarding the characteristics of the same liquid crystal cell as described above using this composition, VLh is 1.51 V, Vsat
F2. Q 9 V,! :Nat.

I”d

Claims (1)

[Scope of Claims] (l) It is represented by the general formula (in the above formula, an alkyl group having 1 to 10 carbon atoms is used, and "cho" is an alkyl group or an alkoxy group having 1 to 10 carbon atoms). 2-Substituted-6-(trans-5-alkyl-1,3-dioxan-2-yl)7talene. (2) General formula R2 represents an alkyl group or an alkoxy group having 1 to 10 carbon atoms. A liquid crystal composition comprising: