JPH041745B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a novel liquid crystal compound that can be used as an electrical display material and has a wide temperature range, and a method for producing this liquid crystal compound. [Technical background of the invention and its problems] Liquid crystals have the property of changing their orientation under the influence of electric or magnetic fields, significantly changing optical properties such as light scattering and birefringence, and are widely used in electrical display devices. It's being used. Liquid crystals used in such display devices are required to have properties such as a wide liquid crystal temperature range, low viscosity, high dielectric anisotropy, and chemical stability. BACKGROUND ART Liquid crystal compounds in which three benzene rings are bonded have been known as liquid crystal compounds. However, since the conventional liquid crystal material with three benzene rings bonded has a high temperature at which it changes from a liquid crystal phase to a crystal, when it is added to a liquid crystal composition, it greatly increases the crystallization temperature, and therefore the crystallization temperature of the composition The drawback was that only a few percent of the amount could be added in order to keep the temperature below 0°C. [Purpose of the Invention] The present inventors focused on the fact that among various liquid crystal compounds, ester-type compounds have a relatively high transition temperature, but are stable in moisture and optical terms. By using a highly polar cyano group or halogen atom as the terminal group and bonding a sulfur-containing ring to the other end group, a larger dielectric anisotropy is imparted to the long axis of the molecule, resulting in a colorless liquid crystal with a wide temperature range. As a result of research on various compounds, we discovered that a series of new compounds containing a thiophene ring exhibit liquid crystallinity over a wide temperature range. That is, an object of the present invention is to provide a novel thiophene-based liquid crystal compound having a wide liquid crystal temperature range, and a method for producing the liquid crystal compound. [Structure of the invention] That is, the liquid crystal compound of the present invention has the general formula (In the formula, R is a linear alkyl group having 2 to 14 carbon atoms, and X is a cyano group, or a fluorine, chlorine, or bromine atom.) The manufacturing method for this liquid crystal compound is (1) General formula (In the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms.) A compound represented by the general formula (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) in the presence of a dehydrating agent, and the general formula (In the formula, R and X have the same meanings as above.)
(2) General formula (In the formula, R is a straight-chain alkyl group having 2 to 14 carbon atoms.) A compound represented by the general formula (in the formula, R has the same meaning as above), and then the general formula (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) A compound represented by the formula: (In the formula, R and X have the same meanings as above.)
(3) General formula (In the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms.) A compound represented by the general formula (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) in the presence of a dehydrating agent, and the general formula (In the formula, R and X have the same meanings as above.)
There is a method to obtain a compound represented by Next, the above-mentioned manufacturing methods (1) and (2) of the present invention will be explained in detail. Production method (1) In this method, the dehydrating agent includes N-hydroxyphthalimide, N,N'-disuccinimidyl carbonate, N,N'-dicyclohexylcarbodiimide, etc., but in particular N,
Using N'-dicyclohexical galbodiimide [method of N. Pravdic et al. (J. Chem. Soc., 4633,
1964)] is preferred. In addition, N,N'-dicyclohexylcarbodiimide is used in an equimolar amount to the 5-n-alkyl-2-thiophenecarboxylic acid of the compound (), and in the presence of pyridine, it is dissolved in a solvent such as dichloromethane, dichloroethane, or carbon tetrachloride. The desired compound can be obtained in one step by dehydration reaction. Production method (2) The chlorinating agent used in this method includes thionyl chloride, phosphorus trichloride, phosphorus pentachloride, etc., and thionyl chloride is particularly preferred from the viewpoint of ease of treatment after the reaction. When thionyl chloride is used, 5 of formula ()
-N-Alkyl-2-thiophenecarboxylic acid may be used in an excess molar amount to reflux, and after the reaction, thionyl chloride may be distilled off under reduced pressure. 5-n-alkyl-2-thiophenecarboxylic acid chloride of formula () and 4-hydroxybenzoic acid of formula ()
The reaction with 4'-substituted phenyl is carried out in an inert solvent such as ethyl ether, benzene, or ethyl acetate, with ethyl acetate being particularly preferred from the viewpoint of solubility.
Further, in order to remove hydrogen chloride generated during the reaction from the system, it is preferable to add a basic substance such as pyridine or triethylamine. The product after the reaction can be subjected to treatments such as organic solvent extraction, water washing, and crystallization to obtain the desired compound. 5-n- of formula () used as a raw material in the present invention
Alkyl-2-thiophenecarboxylic acid can be produced by the following steps. (In the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms, and R ₁ represents a straight-chain alkyl group having 1 fewer carbon atoms than R.) 5-n-alkyl- of formula (d) The manufacturing process up to 2-thiophenaldehyde is based on the method for which the present inventors previously applied for a patent (Japanese Patent Application No. 1986-267133,
-267134, Japanese Patent Application No. 60-55433). 4th stage 5-n-alkyl-2
-thiophenaldehyde to 5-n-alkyl-
The production of 2-thiophenecarboxylic acid requires silver oxide or sodium hypochlorite, potassium hypochlorite,
Oxidation with sodium hypobromite, potassium hypobromite, etc. can also be carried out. In addition, 4'-substituted phenyl 4-hydroxybenzoate, which is the other raw material of the present invention, is
It can be produced by the following method, which is an improvement on the method of No. 13560. (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) In the first step, 4-hydroxybenzoic acid is reacted with acetyl chloride to produce 4-acetoxybenzoic acid of formula (e). . In the second step, 4-acetoxybenzoic acid was added to 4-substituted phenols (4-cyanophenol, 4-fluorophenol, 4-chlorophenol and 4-substituted phenol).
-bromophenol) in the presence of a dehydrating agent to produce 4'-substituted phenyl 4-acetoxybenzoate of formula (f). In the third step, 4'-substituted phenyl 4-acetoxybenzoate can be decomposed with hydrochloric acid in an alcoholic solvent to produce 4'-substituted phenyl 4-hydroxybenzoate of formula (). Examples of other liquid crystal compounds and non-liquid crystal compounds that can be used in combination with the compound of the formula include the following compounds. [In the formula, R and R' are respectively n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R and R' are respectively n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R and R' are respectively n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R is n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R represents n-C _n H _2n+1 ^- , R' represents n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R represents n-C _n H _2n+1 ^- , R' represents n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

【formula】

【formula】

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R represents n-C _n H _2n+1 ^- , R' represents n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

【formula】

【formula】

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R and R′ are respectively n−C _n H _2n+1 ⁻ ,
n−C _n H _2n+1 −O−,

【formula】

【formula】

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R represents n-C _n H _2n+1 ^- , R' represents n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

【formula】

【formula】

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R represents n-C _n H _2n+1 ^- , R' represents n-C _n H _2n+1 ^- , n-C _n H _2n+1 -O-,

【formula】

【formula】

[Formula] Represents either -CN or -NO ₂ (where m is an integer from 1 to 10)] [In the formula, R represents n−C _n H _2n+1 ⁻ , and X represents either F, Cl, or Br (however, m is an integer from 1 to 10)] [In the formula, R represents n−C _n H _2n+1 ⁻ , and X represents either F, Cl, or Br (however, m is an integer from 1 to 10)] [In the formula, R represents n−C _n H _2n+1 ⁻ , and X represents either F, Cl, or Br (however, m is an integer from 1 to 10)] [In the formula, R represents n−C _n H _2n+1 ⁻ , and X represents either F, Cl, or Br (however, m is an integer from 1 to 10) [In the formula, R and R' are n-C _n H _2n+1 ^- , n-C _n
H2n ₊₁ represents either -O-, X represents either -CN or -Br (however, m is an integer of 1 to 10)] The physical properties of the main liquid crystal compound of the present invention are Shown in the table.

【table】

[Table] [Examples of the Invention] Next, the present invention will be specifically explained using raw material production examples, examples, and formulation examples. Raw material production example 1 5-ethyl-2-thiophenaldehyde 7.0g
(0.05 mol) was dissolved in 40 ml of ethanol, and a solution of 18.6 g of silver nitrate dissolved in 40 ml of water was added thereto.
A solution of 10 g of sodium hydroxide dissolved in 300 ml of water was added dropwise to this mixture. After the dropwise addition was completed, stirring was continued for an additional hour, and the resulting silver oxide was filtered. The filtrate was concentrated to approximately 100 ml and acidified with 6N sulfuric acid. The resulting precipitate was recrystallized from 50% aqueous ethanol to obtain 7.3 g of the following compound. Yield 93.6%, melting point 70~
71℃. NMR (δ, CDCl ₃ ) 1.34 (t, 3H, −CH ₃ ) 2.90 (q, 2H, −CH ₂ −) 6.83 (d, 1H, Hb) 7.73 (d, 1H, Ha) 9.15 (S, 1H, -COOH) Raw material production examples 2 to 9 In place of 0.05 mol of 5-ethyl-2-thiophenaldehyde in raw material production example 1, the following compound was used.
The compounds shown in Table 2 were obtained in the same manner as in Production Example 1 except that 0.05 mol was used.

【table】

[Table] Raw material production example 10 27.6 g (0.2 mol) of p-hydroxybenzoic acid was dissolved in 200 ml of acetone containing 30 ml of pyridine and cooled. Acetyl chloride 15.6 while stirring this solution.
ml (0.22 mol) was added dropwise and left at room temperature overnight.
To remove excess acetyl chloride, 10 ml of ethanol was added and the mixture was stirred for 2 hours, then dropped into ice water 2 containing hydrochloric acid for crystallization. The crystals were filtered and recrystallized from 50% methanol to give 32.8 g of p-acetoxybenzoic acid.
I got it. Yield 91.1%. Raw material production example 11 12.6 g (0.07 mol) of p-acetoxybenzoic acid obtained in raw material production example 10, 8.3 p-cyanophenol
g (0.07 mol) was dissolved in 200 ml of dichloromethane containing 10 ml of pyridine, 18.2 g (0.07 mol) of N,N'-dicyclohexylcarbodiimide was added, stirred, and allowed to stand overnight. The produced urea body was filtered off, and the filtrate was concentrated, dissolved in carbon tetrachloride, cooled, and filtered off again. The solvent of the filtrate was distilled off under reduced pressure, methanol was added, the mixture was again heated and dissolved, and the resulting crystals were filtered off after cooling to obtain 16.3 g of 4'-cyanophenyl-4-acetoxybenzoate. Next, 15 g of 4'-cyanophenyl-4-acetoxybenzoate
(0.053 mol) was added with 300 ml of methanol and 0.5 ml of hydrochloric acid, and after refluxing for 4.5 hours, the solvent was distilled off under reduced pressure and recrystallized from 50% methanol to obtain 10.1 g of 4'-cyanophenyl-4-hydroxybenzoate. I got it. The yield was 60.3%. Raw material production example 12 5.4 g (0.03 mol) of 4-acetoxybenzoic acid obtained in raw material production example 10 and p-fluorophenol
3.4 g (0.03 mol) was dissolved in 80 ml of dichloromethane containing 5 ml of pyridine, 6.2 g (0.03 mol) of N,N'-dicyclohexylcarbodiimide was added, stirred, and allowed to stand overnight. The generated urea body was filtered off, and the filtrate was distilled off under reduced pressure. Carbon tetrachloride was added and heated to dissolve, cooled and filtered again. The filtrate was distilled off under reduced pressure and crystallized from methanol to give 4′-
Fluorophenyl-4-acetoxybenzoate
6.9g was obtained. 150 ml of methanol and 0.25 ml of hydrochloric acid were added to 6.9 g of 4'-fluorophenyl-4-acetoxybenzoate, and after refluxing for 4.5 hours, the methanol was distilled off under reduced pressure and crystallized from 50% methanol to obtain 4'-fluorophenyl-4-acetoxybenzoate. 4.4 g of enyl-4-hydroxybenzoate was obtained. Yield 63.2%. Raw material production example 13 p-fluorophenol in raw material production example 12
4'-chlorophenyl-4-hydroxybenzoate 4.9 was prepared in the same manner as in Raw Material Production Example 12 except that 0.03 mol of p-chlorophenol was used instead of 0.03 mol.
I got g. Yield 65.7%. Raw material production example 14 p-fluorophenol in raw material production example 12
6.1 4'-bromophenyl-4-hydroxybenzoate was prepared in the same manner as in Raw Material Production Example 12 except that 0.03 mol of p-bromophenol was used instead of 0.03 mol.
I got g. Yield 69.4%. Next, examples will be described. Example 1 0.78 g of 5-ethyl-2-thiophenecarboxylic acid
(0.005 mol) and 1.20 g (0.005 mol) of 4'-cyanophenyl-4-hydroxybenzoate were dissolved in 60 ml of dichloroethane containing 5 ml of pyridine.
Next, N-N'-dicyclohexylcarbodiimide
1.04 g (0.005 mol) was added, stirred, and allowed to stand overnight. The generated urea body was filtered off, and the solvent of the filtrate was distilled off. The crystals obtained by adding ethanol were recrystallized from ethanol to obtain the following compound 1.42.
I got g. Yield 75.3%. NMR (δ, CDCl ₃ ) 1.38 (t, 3H, −CH ₃ ) 2.94 (q, 2H, −CH ₂ −) 6.90 (d, 1H, Hb) 7.38 (d, 2H, Hc or He) 7.39 (d, 2H, He or Hc) 7.74 (d, 2H, Hf) 7.85 (d, 1H, Ha) 8.24 (d, 2H, Hd) Examples 2 to 5 5-ethyl-2-thiophenecarboxylic acid in Example 1 0.005 0.005 of the following compound instead of mole
The compounds listed in Table 2 were obtained in the same manner as in Example 1 except that moles were used.

【table】

[Table] Example 8 5-butyl-2-thiophenecarboxylic acid 0.92g
(0.005 mol) was added with 3 ml of thionyl chloride and refluxed for 30 minutes. Thereafter, excess thionyl chloride was distilled off under reduced pressure. Next, the obtained reaction product was cooled and 30 ml of ethyl ether was added. Add 1.2% of this solution to 4'-cyanophenyl-4-hydroxybenzoate.
The mixture was added dropwise to a mixture of 10 ml of pyridine and 50 ml of ethyl acetate containing g (0.005 mol), and then left overnight at room temperature. This reaction solution was treated with dilute hydrochloric acid, water, dilute caustic soda, and water in this order. After distilling off ethyl acetate, recrystallize from ethanol to obtain the following compound 1.7.
I got g. Yield 81.1%. NMR (δ, CDCl ₃ ) 0.96 (t, 3H, -CH ₃ ) 1.17-1.89 (m, 4H, -CH ₂ -) 2.90 (t, 2H, -CH ₂ -) 6.89 (d, 1H, Hb) 7.38 (d, 2H, Hc or He) 7.39 (d, 2H, He or Hc) 7.74 (d, 2H, Hf) 7.84 (d, 1H, Ha) 8.24 (d, 2H, Hd) Examples 9 to 11 Examples The compounds listed in Table 4 were obtained in the same manner as in Example 8, except that 0.005 mol of the following compound was used instead of 0.005 mol of 4'-cyanophenyl-4-hydroxybenzoate in Example 8.

[Table] Example 12 5-beptyl-2-thiophenecarboxylic acid 1.14
Add 3 ml of thionyl chloride to 30 g (0.005 mol)
Refluxed for minutes. Thereafter, excess thionyl chloride was distilled off under reduced pressure. Next, the obtained reaction product was cooled and 30 ml of ethyl ether was added. Add this solution to 4′-
Cyanophenyl-4-hydroxybenzoate
The mixture was added dropwise to a mixture of 10 ml of pyridine and 50 ml of ethyl acetate containing 1.2 g (0.005 mol), and then allowed to stand overnight at room temperature. This reaction solution was treated with dilute hydrochloric acid, water, dilute caustic soda, and water in this order. After distilling off ethyl acetate, recrystallize from ethanol to obtain the following compound 1.45.
I got g. Yield 65.9%. NMR (δ, CDCl ₃ ) 0.89 (t, 3H, −CH ₃ ) 1.32 (s, 8H, −CH ₂ −) 1.73 (m, 2H, −CH ₂ −) 2.89 (t, 2H, −CH ₂ −) 6.88 (d, 1H, Hb) 7.38 (d, 2H, Hc or He) 7.39 (d, 2H, He or Hc) 7.72 (d, 2H, Hf) 7.83 (d, 1H, Ha) 8.23 (d, 2H, Hd) Examples 13 to 15 The compounds listed in Table 5 were obtained in the same manner as in Example 12, except that 0.005 mol of the following compound was used in place of 0.005 mol of 4'-cyanophenyl-4-hydroxybenzoate in Example 12. Ta.

[Table] Example 16 (Formulation Example) The following liquid crystal composition (A) shows a liquid crystal phase up to 72.5°C (N→I), and the crystallization temperature (N→C) is 0°C or lower. 43% (weight) 17% (weight) 13% (weight) 17% (weight) 10% (weight) When 5% (weight) of the following compound obtained in the present invention was added to 95% (weight) of this composition (A), the results shown in Table 6 were obtained.

[Table] [Effects of the Invention] As is clear from the above examples, according to the present invention, a liquid crystal compound that can be used in a wide temperature range can be obtained.

Claims (1)

[Claims] 1. General formula (In the formula, R is a linear alkyl group having 2 to 14 carbon atoms, and X is a cyano group, or a fluorine, chlorine, or bromine atom.) 2. The liquid crystal compound according to claim 1, wherein X is a cyano group. 3. Claim 1 in which X is a fluorine atom
Liquid crystal compound described in Section. 4. The liquid crystal compound according to claim 1, wherein X is a chlorine atom. 5. The liquid crystal compound according to claim 1, wherein X is a bromine atom. 6 General formula (In the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms.) A compound represented by the general formula (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) in the presence of a dehydrating agent, and the general formula (In the formula, R and X have the same meanings as above.)
A method for producing a liquid crystal compound, the method comprising obtaining a compound represented by: 7 General formula (In the formula, R represents a straight chain alkyl group having 2 to 14 carbon atoms.) A compound represented by the formula: (in the formula, R has the same meaning as above), and then the general formula (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) By reacting with a compound represented by the general formula (In the formula, R and X have the same meanings as above.)
A method for producing a liquid crystal compound, the method comprising obtaining a compound represented by: 8 General formula (In the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms.) A compound represented by the general formula (In the formula, X represents a cyano group, or a fluorine, chlorine, or bromine atom.) in the presence of a dehydrating agent, and the general formula (In the formula, R and X have the same meanings as above.)
A method for producing a liquid crystal compound, the method comprising obtaining a compound represented by: