JPH0415232B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a liquid crystal compound used as an electrical display material. More specifically, the present invention relates to a novel thiophene-based liquid crystal compound exhibiting a liquid crystal phase over a wide temperature range and a method for producing the liquid crystal compound. (Prior Art) Liquid crystals have the property of changing their orientation under the influence of electric or magnetic fields, thereby significantly changing their optical properties, and are widely used in electrical display devices. The properties required of the liquid crystal used in such display devices are a wide liquid crystal temperature range, low viscosity, high dielectric anisotropy, and
It is desired that the material be optically stable. Conventionally, liquid crystal compounds having three benzene rings bonded to each other have been known, but liquid crystal compounds containing a thiophene ring and having a wide temperature range have not been known. In addition, conventional liquid crystal substances with three benzene rings bonded have a drawback that the temperature at which they change from liquid crystal phase to crystal is high, so when they are added to liquid crystal compositions, they can only be added in a few percent because this increases the crystallization temperature. (Problems to be Solved by the Invention) Among crystalline compounds having two or more rings, azomethine-type compounds, which have been relatively frequently used in practice, have a low transition temperature and are optically stable; Easily hydrolyzed and loses liquid crystallinity in the presence of trace amounts of moisture. On the other hand, the ester type has a relatively high transition temperature, but is moisture and optically stable. In view of the above circumstances, by bonding a highly polar cyano group or halogen atom as the end group of an ester-type compound and bonding a sulfur-containing thiophene ring to the other end, dielectric anisotropy is increased in the long axis direction of the molecule. Colorless from an attempt to give
As a result of researching various liquid crystal compounds over a wide temperature range,
We have discovered that a series of new compounds containing a thiophene ring exhibit liquid crystallinity. That is, a novel biphenyl ester liquid crystal compound of thienyl acrylic acid and thiophene carboxylic acid having a wide liquid crystal temperature range and a method for producing the same,
The purpose is to provide. [Structure of the invention] (Means for solving the problems) That is, the liquid crystal compound of the present invention has the general formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
n is 1 or 0, and X represents a cyano group or a bromine atom). As a compound included in the present invention, the general formula when n is 1 (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
5-n-alkyl-2-thienyl acrylic acid represented by (X represents a cyano group or a bromine atom)
4'-substituted-4-biphenylyl and general formula when n is 0 (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
5-n-alkyl-2-thiefenecarboxylic acid represented by (X represents a cyano group or a bromine atom)
4′-substituted-4-biphenylyl, and as a compound included in the general formula (), the general formula 5-n-alkyl-2-thienyl acrylic acid-4'-cyano-4-biphenylyl represented by (in the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms) and the general formula 5-n-alkyl-2-thienyl acrylate-4-bromo-4-biphenylyl represented by the formula (R represents a straight-chain alkyl group having 2 to 14 carbon atoms), and the general formula ( ) as a compound included in the general formula 5-n-alkyl-2-thiophenecarboxylic acid 4'-cyano-4-biphenylyl represented by (in the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms) and the general formula Examples include 4'-bromo-4-phenylyl 5-n-alkyl-2-thiophenecarboxylate represented by the formula (wherein R represents a straight-chain alkyl group having 2 to 14 carbon atoms). These liquid crystal compounds can be manufactured using the manufacturing method 1 described below.
and can be obtained by manufacturing method 2. Manufacturing method 1 General formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
n is 1 or 0) and the general formula (In the formula, X represents a cyano group or a bromine atom) in the presence of a dehydrating agent to react with the general formula (In the formula, R, n and X have the same meanings as above)
A compound represented by can be produced. In this method, the dehydrating agent includes N-hydroxyphthalimide, N,N'-disuccinimidyl carbonate, N,N'-dicyclohexylcarbodiimide, etc., but N,N'-
N using dicyclohexylcarbodiimide,
Pravdic et al.'s method (J.Chem, Soc, 4633, 1964)
is preferred. In addition, N,N'-dicyclohexylcarbodiimide is used in an equimolar amount to the compound of formula (), and in the presence of pyridine, dichloromethane,
The desired compound can be produced in one step by dehydration reaction in a solvent such as dichloroethane or carbon tetrachloride. Manufacturing method 2 General formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
n is 1 or 0) is reacted with a chlorinating agent to form the general formula (wherein R and n have the same meanings as above), and then the general formula (In the formula, X represents a cyano group or a bromine atom) is reacted in an inert solvent to form the general formula (In the formula, R, n and X have the same meanings as above)
A compound represented by can be obtained. A compound represented by can be obtained. Examples of the chlorinating agent used in this method include thionyl chloride, phosphorus trichloride, and phosphorus pentachloride, but thionyl chloride is particularly preferred from the viewpoint of ease of treatment after the reaction. When thionyl chloride is used, it may be refluxed in an excess molar amount relative to the compound of formula (), and after the reaction, thionyl chloride may be distilled off under reduced pressure. Acid chloride of formula (X) and 4 of formula ()
The reaction with -hydroxy-4'-substituted biphenyl is carried out in a 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-alkyl- used as a raw material in the present invention
2-thienyl acrylic acid and 5-n-alkyl-2-thiophenecarboxylic acid were obtained by the method for which the present inventors previously applied for a patent (Japanese Patent Application No. 59-267133,
59-267134, patent application No. 1983-55433, patent application No. 1983-
No. 260935). (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
(R ₁ represents a straight-chain alkyl group having one carbon atom less than R) In the first step, thiophene is reacted with n-alkylcarboxylic acid or an acid chloride or acid anhydride of n-alkylcarboxylic acid. , an n-alkyl-2-thienyl ketone of formula (a) is produced. In the second step, the 2-n of formula (b) is reduced by reducing the n-alkyl-2-thienyl ketone with hydrazine hydrate in the presence of an ethylene glycol solvent.
-Alkylthiophenes are produced. In the third step, 2-
Reacting n-alkylthiophene with phenyllithium followed by N,N-dimethylformamide, or reacting 2-n-alkylthiophene with N,N-dimethylformamide using phosphorous oxychloride as a catalyst. , 5 of formula (C)
-n-alkyl-2-thiophene aldehyde is produced. In the fourth step, methyl 5-n-alkyl-2-thienyl acrylate obtained by refluxing 5-n-alkyl-2-thiophenaldehyde and methyl acetate in the presence of sodium is subjected to alkaline hydrolysis or a small amount of 5-n-alkyl-2-thienyl acrylic acid of formula (a) is produced by reacting 5-n-alkyl-2-thiophene aldehyde and malonic acid using pyridine containing piperidine as a solvent. Moreover, 5-n-alkyl-2-thiophenecarboxylic acid can be manufactured by the following steps. (in the formula, R represents a straight-chain alkyl group having 2 to 14 carbon atoms) 5-n-alkyl-2-thiophenaldehyde to silver oxide, sodium hypochlorite, potassium hypochlorite, sodium hypobromite , potassium hypobromite or the like. 4-Hydroxy-4'-promobiphenyl, the other raw material of the present invention, is a commercially available product. 4-hydroxy 4'-cyanobiphenyl can be produced by the following steps. It can be produced by reacting 4-hydroxy-4'-bromobiphenyl with cuprous cyanide in N,N-dimethylformamide. Other nematic liquid crystal compounds and non-nematic liquid crystal compounds that can be used in combination with the liquid crystal compound of 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 1
~10 integer)] [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 1
~10) integer)] [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 1
~10 integer)] [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 1
~10 integer)] [In the formula, R represents n−C _n H _2n+1 −, and 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 1
~10 integer)] [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 −O−,

【formula】

【formula】

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

【table】

[Table] (Example) Next, the present invention will be specifically explained with reference to raw material production examples, examples, and formulation examples. Raw Material Production Example 1 To 10 ml of N,N-dimethylformamide were added 12.45 g (0.05 mol) of 4-hydroxy-4'-bromobiphenyl and 5.4 g (0.06 mol) of cuprous cyanide, and the mixture was stirred and refluxed for 5 hours. After the reaction, it was cooled to 70°C. Separately, 22 g (0.08 mol) of ferric chloride hexahydrate was dissolved in 35 ml of an aqueous solution containing 9 ml of hydrochloric acid and added to the above reaction solution. After stirring at 60 to 70°C for 30 minutes, 300 ml of ethyl acetate and 100 ml of water were added, and the mixture was cooled while stirring. The ethyl acetate layer was separated, the aqueous layer was extracted with 150 ml of ethyl acetate, and the previous extracts were combined and treated sequentially with dilute hydrochloric acid and water. After distilling off ethyl acetate, the residue was dissolved in methanol, treated with activated carbon, and crystallized by adding water to obtain 3.9 g of 4-hydroxy-4'-cyanobiphenyl. Yield 39%. Example 1 5-propyl-2-thienyl acrylic acid 098g
(0.005 mol) and 1.25 g (0.005 mol) of 4-hydroxy-4'-bromobiphenyl were dissolved in 60 ml of dichloromethane containing 5 ml of pyridine. Then N,
N'-dicyclohexylcarbodiimide 1.04g
(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 1.52 g of the following compound.
Yield 71.2% NMR (δ, CDCl ₃ ) 1.00 (t, 3H, −CH ₃ ) 1.74 (m, 2H, −CH ₂ −) 2.81 (t, 2H, −CH ₂ −) 6.31 (d, 1H, Hd) 6.77 (d , 1H, Hb) 7.15 (d, 1H, Ha) 7.24 (d, 2H, He) 7.45 (d, 2H, Hh) 7.54 (d, 4H.Hf and Hg) 7.90 (d, 1H,, HC) Example 2-8 0.005 mol of the following compound in place of 0.005 mol of 5-propyl-2-thienyl acrylic acid in Example 1
The compounds listed in Table 3 were obtained in the same manner as in the same Example except that moles were used.

【table】

[Table] Example 9 5-propyl-2-thienyl acrylic acid 0.98g
(0.005 mol) and 0.98 g (0.005 mol) of 4-hydroxy-4'-cyanobiphenyl obtained in Raw Material Production Example 1 were dissolved in 60 ml of dichloromethane containing 5 ml of pyridine. Next, 1.04 g (0.005 mol) of N,N'-dicyclohexylcarbodiimide 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 1.40 g of the following compound. Yield 75.1%. NMR (δ, CDCl ₃ ) 1.00 (t, 3H, −CH ₃ ) 1.74 (m, 2H, −CH ₂ −) 2.82 (t, 3H, −CH ₂ −) 6.31 (d, 1H, Hd) 6.78 (d , 1H, Hb) 7.16 (d, 1H, Ha) 7.28 (d, 2H, He) 7.66 (d, 6H, Hf, Hg and Hh) 7.91 (d, 1H, Hc) Examples 10-13 In Example 9 The compounds listed in Table 4 were obtained in the same manner as in the same Example except that 0.005 mol of the following compound was used in place of 5-propyl-2-thienyl acrylic acid.

[Table] Examples 14-21 0.005 mol of the following compound in place of 0.005 mol of 5-propyl-2-thienyl acrylic acid in Example 1
The compounds listed in Table 5 were obtained in the same manner as in the same Example except that molar values were used.

【table】

[Table] Examples 22 to 26 0.005 mol of the following compound in place of 0.005 mol of 5-propyl-2-thienyl acrylic acid in Example 9
The compounds listed in Table 6 were obtained in the same manner as in the same Example except that moles were used.

【table】

[Table] Example 27 5-ethyl-2-thienyl acrylic acid 0.91g
(0.005 mol) was dissolved in 2 ml of dichloromethane and 2 ml of dichloroethane, 4 ml of thionyl chloride was added, and the mixture was refluxed for 1 hour. Thereafter, the solvent and excess thionyl chloride were distilled off under reduced pressure. The resulting reaction product was cooled and 30 ml of ethyl ether was added. Add this solution to 1.25 g of 4-hydroxy-bromobiphenyl.
(0.005 mol) of pyridine and 70 ml of ethyl acetate
After dropping the solution into a mixed solution with 100 ml, it was 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 ethyl acetate was distilled off, the residue was recrystallized from ethanol to obtain 1.40 g of the following compound. Yield 67.8
%. NMR (δCDCl ₃ ) 1.34 (t, 3H, −CH ₃ ) 2.88 (q, 2H, −CH ₂ −) 6.31 (d, 1H, Hd) 6.78 (d, 1H, Hb) 7.15 (d, 1H, Ha) 7.24 (d, 2H, He) 7.45 (d, 2H, Hh) 7.54 (d, 4H, Hf and Hg) 7.90 (d, 1H, Hc) Example 28 5-ethyl-2-thienyl acrylic acid in Example 27 5-ethyl-2- instead of 0.005 mol
1.02 g of the following compound was obtained in the same manner as in the same Example except that 0.005 mol of thiophenecarboxylic acid was used. Yield 52.7%. NMR (δ, CDCl ₃ ) 1.37 (t, 3H, −CH ₃ ) 2.93 (q, 2H, −CH ₂ −) 6.88 (d, 1H, Hb) 7.28 (d, 1H, Hc) 7.45 (d, 2H, Hf) 7.55 (d, 4H, Hd and He) 7.83 (d, 1H, Ha) Example 29 (Formulation example) The following liquid crystal composition (A) exhibits a liquid crystal phase up to 72.5°C (N→) and does not crystallize. The temperature (N→C) is below 0°C. When 5% (by weight) of the following compound obtained in the present invention was added to 95% (by weight) of this composition A, the results shown in Table 7 were obtained.

[Table] [Effects of the Invention] As described above, a novel thiophene-based liquid crystal compound having a wide liquid crystal temperature range could be obtained.

Claims (1)

[Claims] 1. General formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
A liquid crystal compound characterized in that n is 1 or 0, and X represents a cyano group or a bromine atom. 2 General formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
2. The liquid crystal compound according to claim 1, wherein X represents a cyano group or a bromine atom. 3 General formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
2. The liquid crystal compound according to claim 1, wherein X represents a cyano group or a bromine atom. 4. The liquid crystal compound according to claim 1, wherein X is a cyano group. 5. The liquid crystal compound according to claim 1, wherein X is a bromine atom. 6 General formula (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
n is 1 or 0) and the general formula (In the formula, X represents a cyano group or a bromine atom) is reacted with a compound represented by the general formula (In the formula, R, n and X have the same meanings as above)
A method for producing a liquid crystal compound, the method comprising obtaining a compound represented by: (In the formula, R is a straight chain alkyl group having 2 to 14 carbon atoms,
n is 1 or 0) is reacted with a chlorinating agent to form a compound represented by the general formula (wherein R and n have the same meanings as above), and then the general formula (In the formula, X represents a cyano group or a bromine atom) by reacting with a compound represented by the general formula (In the formula, R, n and X have the same meanings as above)
A method for producing a liquid crystal compound, the method comprising obtaining a compound represented by: