JPS6232193B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to substituted liquid crystalline 1,3-dioxane and materials containing it for electro-optical devices for modulating transmitted or outstanding light and for depicting characters, symbols and images. Regarding. Various electro-optical effects occur in nematic liquid crystals due to their optical and dielectric anisotropy.
It is known that this effect can be useful in the production of electro-optic elements (G. Meier, E. Sackmann, J. G. Grabmaier, “Applications of Liquid Crystals”). Application of Liquid
Crystals”, Springer Publishers
Verlag), Berlin/Heidenberg/New York (1975); N. Tobias' “International Handbook of Liquid Crystal Displays” (International
Handbook of Liquid Crystal Displays”, 1975
~76, Ovum Ltd, London (1976)]. Of particular interest here are elements based on twisted nematic layers, in which the intersections are removed under the influence of an electric field and appear by light-dark effects. The premise of this type of element is the use of nematic materials with positive dielectric anisotropy found in compounds with a strong linear component of the dipole moment. Materials with negative dielectric anisotropy exhibit dynamic scattering effects that are likewise suitable for electro-optical elements. The materials conventionally used for optical and electrical components have melting points that are too high or clearing points that are too low, or are unstable to thermal loads, light and chemicals as well as electric fields or interfering natural colors. It has all the definite drawbacks of being low. The object of the invention is a nematic liquid-crystalline material having favorable properties with respect to melting point, clearing point and stability to the effects of thermal loads, light and chemicals and electric fields and to colorlessness. This problem is solved in accordance with the present invention by creating a new nematic liquid crystal material and a hitherto unknown method for synthesizing the same. The inventor has determined that the general formula [In the formula, X is

[Formula] and Y means R ² , or X means R ⁴ and Y means

[Formula] or X is

[Formula] and Y is

[Formula], and R ¹ is CnH _2o+1 , CnH _2o+1 O, CnH _2o+1
-COO,

【formula】

[Formula] CnH _2o+1 OCOO, CN, NO ₂ , halogen or NC—CH ₂ —CH ₂ , R ² means CnH _2o+1 or OR ⁴ , R ³ means CnH _2o+1 , CnH _2o+1 means O, CN or Br and R ⁶ means CnH _2o+1 , provided that n=1-10. ] Liquid crystalline 2, 1,3-dioxane represented by
5-Disubstituted derivatives are prepared by the following general reaction of alkanalenes, substituted benzaldehydes or their acetals with glycerin or 2-substituted propanediol (1,3) in an organic solvent in the presence of an acidic catalyst. It has been found that by reacting and optionally further esterifying or etherifying it can be obtained according to the formula: The novel compounds are used according to the invention in a mixture containing at least one substance according to the invention. It is particularly advantageous for the substances of the invention to be in a mixture with each other and with other liquid-crystalline or non-liquid-crystalline substances. The advantage of the materials of the invention is that they have a sufficiently high clearing point and a low melting point, and that they are stable to the effects of heat, light, chemicals and electric fields. Substances with three rings have the advantageous property of significantly increasing the clearing point of the mixture. The present invention will be explained in more detail in the following examples. Example 1: 2-alkyl-propanediol-(1,3)
- See Table 1 - and 2-[4-substituted phenyl]-propanediol - 1,3 - See Table 2 - Preparation of 21 g (0.5 mol) of LiAlH ₄ in a three-necked flask of 2. 1 in anhydrous ether. 1 mol of n-alkyl-malon ester or 1 mol of 4-substituted ester mixed with the same volume of anhydrous ether under ice cooling and vigorous stirring.
Phenyl-malon ester is added slowly and then stirred for a further 2 hours at room temperature. This solution is then carefully mixed with 100 ml of ice water. The resulting precipitate [Al(OH) ₃ , LiOH] was added to 700 ml of 10%
Dissolved by addition of H ₂ SO ₄ . The organic phase is separated, the aqueous layer is washed twice with ether and the combined organic phases are washed with 2% NaHCO ₃ solution and water. After drying over Na ₂ SO ₄ the solvent is distilled off under reduced pressure and the residue is fractionally distilled. Examples are shown in Tables 1 and 2.

【table】

[Table] Example 2: Production of compounds of formulas 1, 2, and 3 with 0.1 mol of alkanal or 0.1 mol of substituted benzaldehyde or its acetal
0.11 moles of 2-alkyl-propanediol
(1,3) or 0.12 mol of glycerin or
0.11 mol of 2-[4-substituted phenyl]-propanediol-(1,3) was dissolved in 100 mg of p-toluene-sulfone in 150 ml of anhydrous benzene, chloroform, methylene chloride, carbon tetrachloride, or toluene. Heat in the presence of acid or AlCl ₃ , SbCl ₅ , TiCl ₄ or 2 ml of mineral acids (HCl, H ₂ SO ₄ , H ₃ PO ₄ ) with stirring from separation of the water until the end of the reaction. After cooling the reaction mixture, it is washed with 2% NaHCO ₃ solution and water and dried over Na ₂ SO ₄ .
The solvent is distilled off in a rotary evaporator and the residue is recrystallized from methanol. The yield is approximately 80% of the theoretical amount
~100%. Examples are summarized in Tables 3, 4 and 5. In each table, K is a crystalline solid, S _A and S _B are smectic A or B, N is nematic, and I
means isotropic liquid. The numerical values in the table are transition temperatures, and the unit is °C. 〓 in the table means that the described liquid crystal phase exists,
- means that the described liquid crystal phase is not present. ( ) means univariate metastasis. The measurement of the transition temperature is carried out in the customary manner.

【table】

【table】

【table】

[Table] Example 3: Three methods for etherifying 2-[4-hydroxy-phenyl]-5-alkyl-1,3-dioxanes (1) 0.1 mol of 2-[4-hydroxy-phenyl] ]-5-alkyl-1,3-dioxane 50
ml of anhydrous tetrahydrofuran and
Mix with 0.12 mole sodium hydride. After stirring for 2 hours, 0.12 mol of the corresponding alkyl bromide are added and the reaction mixture is heated under reflux for 4 hours. The solvent was then distilled off in a rotary evaporator, the reaction product was taken up in 100 ml of ether and the ether phase was separated twice at 100 ml.
Wash with ml of water. Next, dry with Na ₂ SO ₄
The solvent is distilled off and the residue is recrystallized from methanol (Table 6). (2) 0.1 mole of 2-[4-hydroxy-phenyl]-5-alkyl-1,3-dioxane was dissolved in a little benzene and 0.23 g (0.1 g-atom) of sodium was dissolved in 100 ml of anhydrous toluene. Suspend and add to the suspension. After heating to 80° C. for 3 hours, it is cooled to room temperature and 0.11 mol of alkyl bromide is added. 80℃ for 4 hours
After heating to and cooling the reaction mixture, it is washed with water, dried over Na ₂ SO ₄ , the solvent is distilled off and the reaction product is crystallized from methanol (Table 6). (3) 0.1 mol of 2-[4-hydroxy-phenyl]-5-alkyl-1,3-dioxane,
A solution of 0.23 g (0.1 g-atom) of sodium in 100 ml of absolute ethanol is introduced under stirring. followed by 0.1 mole of alkyl-
Bromide is added and the reaction mixture is heated under reflux for 4 hours. After distilling off the solvent, the residue is taken up in ether, washed, dried over Na ₂ SO ₄ , the ether is distilled off and the reaction product is recrystallized from methanol (Table 6).

[Table] Example 4: Esterization of 2-[4-hydroxy-phenyl]-5-substituted-1,3-dioxanes and 2-[4-substituted-phenyl]-5-hydroxy-1,3-dioxanes (1) 0.1 mol of the sodium salt of 2-[4-hydroxy-phenyl]-5-substituted-1,3-dioxanes (prepared according to Example 3) is added to 50 ml of anhydrous Tetrahydrofuran, ether,
React with 0.15 mol of the corresponding acid chloride in benzene or toluene with stirring. The reaction mixture is left overnight, the solvent is evaporated, the residue is taken up in ether, washed, dried over Na ₂ SO ₄ and recrystallized from methanol. Yield is 90-95% of theoretical value. (2) 0.1 mole of 2-[4-hydroxy-phenyl]-5-substituted-1,3-dioxane or
0.1 mol of 2-[4-substituted-phenyl]-5-
Hydroxy-1,3-dioxane was dissolved in 15 ml of anhydrous pyridine and under cooling and stirring.
0.11 mol of the corresponding acid chloride is added gradually. The reaction mixture is left to stand overnight, after which the solvent is distilled off and the residue is worked up as described under (1) above. The yield is 90% of the theoretical value.

【table】

[Table] The compounds listed in Table 8 were synthesized by the method described in Example 4.

[Table] Example 5: 5-alkyl-2-[4-(β-cyanoethylexy)-phenyl]-1,3-dioxane and 5-[β-cyanoethylexy]-2-[4-
Synthesis recipe of substituted-phenyl]-1,3-dioxane: 0.1 mol of 5-alkyl-2-[4-hydroxyphenyl]-1,3-dioxane or
0.1 mol of 2-[4-substituted-phenyl]-5-hydroxy-1,3-dioxane - described in Example 2, which is obtained using glycerol as starting compound. - solution at 35-40℃
300mg of sodium methylate and
Add 0.12 mol of acrylonitrile. The reaction mixture is stirred at room temperature for 6 hours and then extracted with ether. The ether phase is washed, dried over caustic potash and the solvent is distilled off. The residue is crystallized from methanol. The yield is 54-80% of the theoretical value. Example 6: 5-n-hexyl-2-[4-cyan-phenyl]-1,3-dioxane (compound Nr.1.30)
is suitable for opto-electrical elements based on twisted nematic layers and has the following properties: Measurement temperature: 35 °C Threshold voltage: 0.65 V/50 Hz Rise time t _E (50%): 376 ms (u=
(under 1.3V/50Hz) Fall time t _A (50%); 190ms, layer thickness
21μm Example 7: The materials No. 1 and 33 (see Table 3) are below the clearing point.
It exhibits a strong positive dielectric constant anisotropy of Δε=+11 at 10°C. Example 8: 1 part by weight

[Formula] (compound 1.4) and 1 part by weight

A mixture with [Formula] (compound 1.11) exhibits the following physical properties: △ε=+0.5 Viscosity=36.6 cp (20°C) △n=0.085 Example 9 The following dioxane components A mixture consisting of exhibits the following physical properties: Measurement temperature: 20℃, Threshold voltage: Uot = 0.8V Connection time under U = 2 × Uot = 1.6V t _E50 % = 336 mμ t _A50 % = 74 mμ A mixture consisting of the following compounds exhibits the physical properties listed below. : Threshold voltage: Uot=1.1V Connection time under U=2×Uot=2.2V _tE50 %=213mμ _tA50 %=107mμ Examples of mixtures of the compound of the present invention and known liquid crystals are shown below. And show its physical properties: *Mixture 14 has the following composition: The transition temperature of mixture 14 is as follows.

[Table] 〓
t _A50 〓 46 mμ 59
mμ
〓

Claims (1)

[Claims] 1. General formula [In the formula, X means [formula] and Y means R ² , or X means R ⁴ and Y means [formula], or X means [formula] and Y means [formula] and R ¹ is CnH _2o+1 , CnH _2o+1 O, CnH _2o+1
-COO, [Formula] [Formula] CnH _2o+1 OCOO, CN, NO ₂ , halogen or NC-CH ₂ - means CH ₂ , R ² means CnH _2o+1 or OR ⁴ , R ³ CnH _2o+1 , CnH _2o+1 O, CN or Br and R ⁴ means CnH _2o+1 , with n=1-10. ] Liquid crystalline 2, 1,3-dioxane represented by
5-Disubstituted derivatives. 2 General formula [In the formula, X means [formula] and Y means R ² , or X means R ⁴ and Y means [formula], or X means [formula] and Y means [formula] and R ¹ is CnH _2o+1 , CnH _2o+1 O, CnH _2o+1 ―COO,
[Formula] [Formula] CnH _2o+1 OCOO, CN, NO ₂ , halogen or NC
-CH ₂ - means CH ₂ , R ² means CnH _2o+1 or OR ₄ , R ³ means CnH _2o+1 , CnH _2o+1 O, CN or Br and R ⁴ means CnH _{2o +1} , provided that n=1 to 10. ] Liquid crystalline 2, 1,3-dioxane represented by
In producing 5-disubstituted derivatives, alkanals, substituted benzaldehydes, or their acetals are treated with glycerin or 2-substituted propanediol (1,3) in an organic solvent in the presence of an acidic catalyst. ) and react according to the following general reaction formula, The method for producing the above-mentioned liquid crystalline 2,5-disubstituted derivative of 1,3-dioxane, which further comprises esterification or etherification depending on the case. 3 General formula [In the formula, X means [formula] and Y means R ² , or X means R ⁴ and Y means [formula], or X means [formula] and Y means [formula] and R ¹ is CnH _2o+1 , CnH _2o+1 O, CnH _2o+1 ―COO,
[Formula] [Formula] CnH _2o+1 OCOO, CN, NO ₂ , halogen or NC
-CH ₂ - means CH ₂ , R ² means CnH _2o+1 or OR ⁴ , R ³ means CnH _2o+1 , CnH _2o+1 O, CN or Br and R ⁴ means CnH _{2o +1} , provided that n=1 to 10. ] Liquid crystalline 2, 1,3-dioxane represented by
A liquid crystal composition for electro-optical elements for modulating transmitted or reflected light and for depicting characters, symbols and images, characterized in that it contains at least one type of 5-disubstituted derivative.