JPS6317848A - Optically active 6-substituted naphthalene-2-carboxylic acid ester compound and liquid crystal - Google Patents

Abstract

NEW MATERIAL:A compound shown by formula I (R1 is 4-18C alkyl; R2 is optically active alkyl; X is C or N). EXAMPLE:6-(6'-n-Octyloxypyridyl-3'-carbonyloxy)naphthalene-2-carboxylic acid (S)-2-methylbutyl ester. USE:One component for a liquid crystal composition. Chiral smectic C liquid crystal useful as a display element material having improved weather resistance, smectic liquid crystal and especially ferroelectricity. Liquid crystal temperature range of chiral smectic C phase of the liquid crystal composition can be effectively extended by using the compound as one component for another liquid crystal compound. PREPARATION:A compound shown by formula II is reacted with thionyl chloride according to the reaction formula to give a compound shown by formula III. Then this compound is dissolved in an aromatic hydrocarbon solvent such as benzene, etc., and reacted with a compound shown by formula IV in the presence of pyridine, etc., to give a compound shown by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to novel 6-substituted naphthalene-2-carboxylic acid ester compounds.

Such 6-substituted naphthalene-2-carboxylic acid ester compounds are useful as liquid crystal compounds.

Liquid crystals include nematic liquid crystals, smectic liquid crystals, and cholesteric liquid crystals, among which the compound of the present invention is a smectic liquid crystal, particularly a chiral smectic C liquid crystal that has ferroelectricity and is useful as a display element material. Furthermore, such chiral smectic liquid crystals can also be used in optoelectronic instruments such as optical printer heads, optical Fourier transform elements, and light valves.

[Conventional technology]

Chiral smectic Ce crystal has a helical structure with a fairly long pitch length, but in cells with a cell gap shorter than the pitch length of the helical structure, it exhibits residual spontaneous polarization and exhibits extremely high velocity (1 ~100 microseconds) and also exhibits memory properties (N, A,
C1ark et al App 1. Phys, Let t,,3
6.899 (1980)).

By utilizing the light switching phenomenon of chiral smectic C liquid crystal, it becomes possible to produce a liquid crystal display element with much faster response time than the conventional twisted nematic type liquid crystal display element, making it possible to produce large-screen liquid crystal displays. It is possible to put the device into practical use.

As such chiral smecti Tsuku C4 & products,
p-Decyloxybenzylidene-p-amino-2-methylbutylcinnamate (hereinafter abbreviated as DOBAMBC) is known (R, B).

See Meyer et al. J, de Physique 3rd, L-69 (1975)).

Although some nematic liquid crystals having a 6-substituted naphthalene-2-carboxylic acid ester skeleton have been reported, there are few examples of smectic liquid crystals, and in particular, 6-n-alkoxynaphthalene-2 has been identified as smectic C liquid crystal. −
Carvone W-4--n-flucoxyphenyl ester is almost the only example (D, Coates and G
, W., Gray, Mo 1. Crys t, L iq,
Cryst.

Vol, 41. p197 (1978)).

[Problem that the invention seeks to solve]

However, since DOBAMBC has a Schiff base structure, it is unstable to moisture, and the ethylene structure of cinnamic acid is unstable to light, which is a serious drawback. That is, it cannot be widely used as a liquid crystal because of its poor weather resistance.

[Means and effects for solving the problems] The present inventors have conducted extensive studies with the aim of providing a novel compound exhibiting chiral smectic CW crystallinity with excellent weather resistance. As a result, the general formula (I ) (In the formula, R□ has 4 to 18 carbon atoms.
We have discovered an optically active 6-substituted naphthalene-2 carboxylic acid ester compound represented by It was discovered that the desired chiral smectic C liquid crystal can be obtained in a temperature range around room temperature, and the present invention was achieved. Furthermore, since such a compound has good mutual solubility with other liquid crystal compounds, when used as a component of a liquid crystal composition, it is effective in expanding the liquid crystal temperature range of the chiral smectic C phase of the liquid crystal composition. R+ in general formula (I)
is an alkyl group having 4 to 18 carbon atoms. Also, the general formula (
R2 in I) is an optically active alkyl group, and those that can be preferably used include an optically active 2-methylbutyl group,
2-methylpentyl group, 2-methylhexyl group, 2-methylheptyl group, 2-methyloctyl group, 1-methylpropyl group, 1-methylbutyl group, 1-methylpentyl group, 1-methylhexyl group, 1-methyl heptyl group, 3-
Examples include methyl pendel group, 3-methylhexyl group, 3-methylheptyl group, 5-methylheptyl group, and use of optically active 2-methylbutyl group is particularly preferred.

Optically active 6-substituted naphthalene of general formula (I) of the present invention
2-Carboxylic acid ester compounds do not have functional groups that are unstable to moisture or light, such as azomethine, azo, azoxy, or ethynyl groups as structural components, and are composed only of stable ester and ether groups. Therefore, it has very excellent weather resistance and becomes a chiral smectic CM crystal in the temperature range around room temperature, so it is highly practical.

-IG The optically active 6-substituted naphthalene-2-carboxylic acid ester compound of formula (I) can be synthesized according to the reaction formula described below.

Li----→ (I) After heating the compound of formula (II) with an excess amount of thionyl chloride under reflux for several hours, unreacted thionyl chloride was removed by distillation under reduced pressure, and the corresponding acid chloride ( III) is obtained. Next, acid chloride (III) is dissolved in an aromatic hydrocarbon solvent such as benzene or toluene, and 6-hydroxynaphthalene-2-carboxylic acid optically active alkyl ester ( By reacting with IV) for several hours at room temperature or under heating conditions,
A compound of general formula (I) is synthesized. The obtained crude compound (I) is purified by column chromatography, recrystallization, or other methods.

When X is a nitrogen atom in the compound of formula (II), a known method (A, 1. Pavluchenk.

et al Mo1. Cryst, Liq, Cr
yst.

37, No. 1-4, p. 35 (1976)),
It can be synthesized by reacting an anhydrous alcohol having 4 to 18 carbon atoms with total sodium to give the corresponding alcoholade, and reacting this alcoholade with 6-chloropyridine-3-carboxylic acid.

It can also be synthesized by reacting an alkali metal salt of 6-hydroxypyridine-3-carboxylic acid with an alkyl halide having 4 to 18 carbon atoms in a polar aprotic solvent such as dimethylformamide. When X is a carbon atom in the compound of formula (II), it can be synthesized by reacting 4-hydroxybenzoic acid with an alkyl halide having 4 to 18 carbon atoms in a mixed solution of potassium hydroxide in ethanol/water.

The compound of formula (IV) is 6-hydroxynaphthalene-2
- A method of esterifying carboxylic acid (V) with a predetermined optically active alcohol in the presence of a sulfuric acid catalyst, or a method in which the hydroxy group is protected as a benzyl ether, and then converted to an acid chloride and reacted with a predetermined optically active alcohol, It can be easily synthesized by hydrogenolysis of benzyl ether, which is a protecting group.

6-Hydroxinaphthalene-2-carboxylic acid of formula (V) can be synthesized by reacting β-naphthol potassium salt with carbon dioxide (Japanese Patent Application Laid-Open No. 57-959).
39), 7 Alternatively, as an alternative method, the hydroxy group of 2-bromo-6-hydroxynaphthalene (Vt) is methylated with dimethyl sulfate under alkaline conditions to obtain 2-bromo-6-methoxynaphthalene (■). , reacted with acetyl chloride in the presence of anhydrous aluminum chloride catalyst in nitrobenzene solvent to give 2-acetyl-6-methoxynaphthalene (■), followed by 6-med by oxidation with sodium hypobromite in dioxane solvent. A method of preparing xinaphthalene-2-carvone R (IX) can also be carried out. Compound (IX) can be converted to 6-hydroxynaphthalene-2-carboxylic acid (V) by reacting with hydrobromic acid in an acetic acid solvent (Q, W
, G ra yand Brynmor Jones
, J. Chem, Soc, p678 (1954)
reference).

Compound (IX) can also be directly synthesized by Grignard reaction of compound (■) (Fries
and K., Schimelschmidt, Ber.
(See p. 2835 (1925)).

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 6-(6--n-octyloxypyridyl-3-1carbonyloxy)naphthalene-2-carbon a(S)-2-
Methyl butyl ester (general formula % formula %) 6-hydroxynaphthalene-2-carboxylic acid 10.0g
(0,053 mol), (S)-2-methylbutyl alcohol 14.1 g (0,160 mol), concentrated sulfuric acid 0.5
A mixed solution of 2 g and 30 ml of toluene was heated under reflux for 6 hours while azeotropically removing by-product water. Ether 10 after cooling
Add 0ml to extract the generated ester and increase the ether calendar to 5
% sodium bicarbonate aqueous solution twice, washed with water, and dried over anhydrous magnesium sulfate. The crude product obtained by distilling off the solvent under reduced pressure was purified by silica gel column chromatography and recrystallization from a mixed solvent of n-hexane/ethyl acetate/benzene to obtain 6-hydroxynaphthalene-2-carboxylic acid (S )-2-methylbutyl ester (8.96 g (yield 65%)) was obtained. The melting point of this compound was 84-5°C.

1 part sodium chloride in 125 ml n-octyl alcohol
．． After adding 61 g (0.07 mol) and dissolving the resin, 6-chloropyridine-3-carboxylic acid 5. og
(0,032 mol) was added and heated at 150°C for 15 hours.
I stirred it. The obtained solid product was separated, washed with 150 ml of n-hexane, and recrystallized with 50 ml of acetic acid to obtain 6.3 g (yield: 78%) of 6-n-octyloxypyridine-3-carboxylic acid. Obtained. The melting point of this compound was 90-91°C.

This 6-n-octyloxypyridine-3-carboxylic acid 0
．． 63g (2.5 mmol) to 6.0g thionyl chloride
After heating under reflux for 3 hours, unreacted thionyl chloride was distilled off under reduced pressure. The obtained crude acid chloride was mixed with benzene 1
0.77 g (3.0 mmol) of 6-hydroxynaphthalene-2-carboxylic acid (S)-2-methylbutyl ester, and 0.0 ml of triethylamine.
76 g (7.5 mmol) of the mixture at room temperature,
The mixture was heated under reflux for 3 hours. After cooling, the reaction mixture was filtered, and the filtrate was washed successively with 1N-HCl, 1N-NaOH, and saturated brine, and dried over anhydrous magnesium sulfate. The crude product obtained by distilling off the solvent under reduced pressure was purified by silica gel column chromatography and recrystallization from an ethanol/benzene mixed solvent. The obtained 6-(6--n
The yield of -octyloxypyridyl-3'-carbonyloxy)naphthalene-2-carvone M(S)-2-methylbutyl ester was 0.93 g, giving a yield of 76%.

The infrared absorption spectrum of this compound is shown in FIG. The δ (ppm) of It (CDCl2, TMS internal standard) was as follows.

6.72-9.05 (m, 9H, pyridine ring and naphthalene ring) 4.42 (t, J=6Hz, 2H, 〇-Ω above CH2
) 4.30 (d, J=6Hz, 2H,0-CH--CH
) 0.6 to 2.20 (m, 24H) The results of elemental analysis of this compound were as follows, and were well consistent with the theoretical values. Theoretical value (C30H37NOs and LT
) C73,29% 87.59% N2.85%
Analysis values: C73.0% H7.6% N 3.0%.

Based on the above analytical data, this compound is 6-(6=-n
-Octyloxypyridyl-3'-carbonyloxy)naphthalene-2-carboxylic acid (S)-2-methylbutyl ester.

Further, this compound had a melting point of 42.2°C, exhibited the following liquid crystal phase transition upon cooling, and had a monotropic chiral smectic C phase near room temperature.

Examples 2-3 6-n-octyloxy-pyridine-3 in Example 1
The following 6-(6--n-alkoxypyridine-3'- Carbonyloxy)naphthalene-2-carboni (S)-2-methylbutyl ester was synthesized.

Example 26-(6'-n-doboxyviridyl-3'
-carbonyloxy)naphthalene-2=carbon a(S
)-2-methylbutyl ester (in general formula (I), R1=cr2H=s, R,=(S)-2-methylbutyl, X=N) Example 36-(6=-n-hexyloxypyridyl) 3-
monocarponyloxy]naphthalene-2-carvone Hff
(S)2-methylbutyl ester (general formula CI), Rx=C5Htt, R2=(S)-2-methylbutyl,
Performed by MR spectroscopy (CDC1x, TMS internal standard) and elemental analysis.

The results of the liquid crystal phase transition temperatures of the compounds of Examples 2 and 3 are shown in Table 1 together with the results of Example 1.

Examples 4-6 6-n-octyloxypyridine-3- in Example 1
The following 6-(4--n-alkoxyphenyl-1-1-carponyloxy) was prepared in exactly the same manner as in Example 1, except that the carboxylic acid was changed to 4-n-alkoxybensikoic acid corresponding to the desired product. Naphthalene-2-carbon u (S)
2-methylbutyl ester was synthesized.

Example 46-(4'-n-octyloxyphenyl-1-
monocarponyloxy)naphthalene-2-carboxylic 9(S
)-2-methylbutyl ester (in general formula (I), Rs = Cs H1'', R2 = (S) -2-methylbutyl, X = C) The infrared absorption spectrum of this compound is shown in Figure 2. ,” HNMR spectrum (CDC
13, TMS internal standard) was as follows.

6.80-8.70 (m, IOH, benzene ring and naphthalene ring) 4.25 (CiSJ=6Hz, 2H, 〇-Ω upper knee C
H) 4.02 (t, J=6Hz, 2H, 〇-ΩH.

-CHt) 0.7 to 2.20 (m, 24H) The results of elemental analysis of this compound are as follows, and were in good agreement with the theoretical values. Theoretical value (as CxtH1sO5) C75.89% 87.81% Analysis value C7
Analytical data of 5,7% H8,0% or more indicate that this compound is 6-(4''-n-octyloxyphenyl-1'-
carbonyloxy)naphthalene-2-carboxylic acid (S)
It was identified as -2-methylbutyl ester.

Example 56-(4--n-dobutyloxyphenyl-1'
-carbonyloxy)naphthalene-2-carboxylic acid (
S)-2-methylbutyl ester (in general formula (I), R1=CtzH:s, R2=(S)-2-methylbutyl group X=C) Example 66-(4--n-hexyloxyphenyl- 1′
-carbonyloxy)naphthalene-2-carboxylic acid (
S)-2-methylbutyl ester (R1" Cs Htz, R, = (S)-2-methylbutyl, X = C in general formula (I)) Liquid crystal phase transition temperature of the compounds of Examples 4.5 and 6 The measurement results are shown in Table 1.

Example 7 The compound of Example 4 was sealed in a cell made of ITO glass using a 1 μm thick polyethylene terephthalate film as a spacer, and oriented using a temperature gradient method. Tc-
Triangular wave method (Tc indicates the transition temperature from smectic A phase to chiral smectic C phase)
When the spontaneous polarization was fixed at δ11 at a peak height of 100 V and 5 Hz, PS = 2.2 nC/cm2 and DOB A
The value was comparable to that of MBC.

Furthermore, when a rectangular wave with a peak height of 20 V and a frequency of IHz was applied, rapid switching was observed with a response time of 400 microseconds.

Example 8 (Liquid crystal composition) 6-(6=-n-doboxyviridyl-3 of Example 2)
'-carbonyloxy)naphthalene-23-carbon M
(S)-2-methylbutyl ester (RI=C1:!H2S, R2= (S)-2-methylbutyl, X=N in general formula (I)) and 6-(4- −
A liquid crystal composition was prepared by mixing equimolar amounts of n-decylbiphenyl-4-carbonyloxy)pyridine-3-carbon a (S) 2-methylbutyl ester.

The melting point of this liquid crystal composition was 44.8° C., the phase transition temperature upon cooling was as follows, and it had an enantiotopic chiral smectic C phase near room temperature.

95@56'-3''' I (liquid) → SA-- → Sc'''-- → C (crystal)
The phase transition temperature of compound (X) alone upon cooling is as follows.

11→C (crystal) Example 9 (Liquid crystal composition) 6-(6--n-octyloxyviridyl-3 of Example 1)
'-Carbonyloxy)naphthalene-2-carboxylic acid
(S)-2-methylbutyl ester (R□=Ca H1'', R2=(S)-2-methylbutyl, X=N in general formula (I)) and 6-(4-n of Example 6) -hexyloxyphenyl-1'-carbonyloxy)naphthalene-2-carbon a(S)-2-methylbutyl ester (general formula % formula % () -methylbutyl, X=C) is mixed in equimolar amounts to produce a liquid crystal A composition was prepared.

The melting point of this liquid crystal composition was 42°C (47°C), the phase transition temperature upon cooling was as follows, and it had a monotropic chiral smectic C phase near room temperature.

Example 10 (Liquid crystal composition) 6-(6'-n-doboxyviridyl-3 of Example 3)
'-Carbonyloxy)naphthalene-2-carboxylic acid
(S)-2-methylbutyl ester (in general formula (I), R1=CI28?jS, R2=(S)-2-methylbutyl, X=N) and 6-(4--n- of Example 6) xyloxyphenyl-1'-carbonyloxy)naphthalene-2-carvone H(S)-2-methylbutyl ester (
A liquid crystal composition was prepared by mixing equimolar amounts of the general formula % (1 methylbutyl, X=C).

The melting point of this liquid crystal composition is 22.6°C, and the phase transition temperature upon cooling is as follows. Although the compound of Example 6 alone does not have a chiral smectic C phase, it can be used as a mixture. As a result, it had a monotropic chiral smectic C phase near room temperature.

〔Effect of the invention〕

According to the present invention, a novel 6-substituted naphthalene-2-carboxylic acid ester compound can be provided. Furthermore, the compound of the present invention is stable against moisture and light, has excellent weather resistance, and forms chiral smectic CJFI crystals in a temperature range around room temperature.

[Brief explanation of the drawing]

Figure 1 shows the compound of Example 1, 6-(6--n-octyloxypyridyl-3'-carbonyloxy)naphthalene-2-carboxylic acid (S)-2-methylbutyl ester, and Figure 2 shows the compound of Example 1. 2 is a chart of the infrared absorption spectrum of 6-(4--n-octyloxyphenyl-1'-carbonyloxy)naphthalene-2-carboxylic acid (S)2-methylbutyl ester, which is the compound of Example 4. Patent application Daitoshi Co., Ltd. 114! g duck vine

Claims (3)

[Claims] (1) General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 represents an alkyl group having 4 to 18 carbon atoms,
R_2 is an optically active alkyl group, X is a carbon atom or a nitrogen atom) An optically active 6-substituted naphthalene-2-carboxylic acid ester compound. (2) Optically active 6 according to claim 1, wherein R_2 in general formula (I) is an optically active 2-methylbutyl group.
-Substituted naphthalene-2-carboxylic acid ester compound. (3) General formula (I) ▲Mathematical formula, chemical formula, table, etc.▼(I) (In the formula, R_1 represents an alkyl group having 4 to 18 carbon atoms,
R_2 is an optically active alkyl group, X is a carbon atom or a nitrogen atom) A liquid crystal comprising an optically active 6-substituted naphthalene-2-carboxylic acid ester compound.