JPH0796529B2 - Optically active compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel optically active compound.

More specifically, it relates to an optically active compound useful as an intermediate for a novel optically active liquid crystal compound.

[Conventional technology]

At present, various liquid crystal display devices have been put into practical use. Above all, TN (Twisted Nematic) using nematic liquid crystal
The type display method has excellent performance of extremely low power consumption and is widely used. However, this display method has a drawback that the response speed is slow.

Recent advances in industrial technology strongly demand high-speed response for liquid crystal display elements, and various attempts have been made by improving liquid crystal materials to meet such requirements. In order to meet the above demand, a display device utilizing an optical switching phenomenon of a ferroelectric liquid crystal using an optically active smectic liquid crystal has already been proposed (Applied Physics Letter (Appl.Phys.Lett., 36 , 899). (1980)).

[Problems to be solved by the invention]

As a representative of known ferroelectric liquid crystals, there is one shown in Table 1.

However, these compounds have an unstable element that causes isomerization by light within a short period of time, and causes hydrolysis due to moisture so as not to show a liquid crystal phase, which is not preferable as a display element. Also, the spontaneous polarization is small at about 1 to 5 nC / cm ^2, and the response time is slow at about 1 msec. The subject of the present invention is photochemical and chemical stability that eliminates such unstable elements. And to provide a novel compound useful as an intermediate of a ferroelectric liquid crystal having a large spontaneous polarization and a high response speed.

[Means for solving problems]

The present inventors have arrived at the present invention by searching various compounds in order to solve the above problems.

That is, the invention has the general formula (I) (Wherein R represents an alkyl group having 2 to 10 carbon atoms and * represents an asymmetric carbon atom).

The compound of formula (I) can be produced by various methods, but typically, it is produced by the following synthetic route.

(R and * are the same as above, Bz represents a benzyl group), that is, 2,6-hydroxynaphthalenecarboxylic acid (a) is benzylated to form compound (b), and then thionyl chloride and oxalic acid chloride are added. And the like to obtain the acid chloride derivative (c). And (c) and various optical activities 2
An ester form (d) is obtained by reacting with a primary alcohol.
Then, it can be debenzylated with hydrogen in the presence of palladium / carbon to produce compound (I). The 2,6-hydroxynaphthalenecarboxylic acid used for the production of the compound (I) of the present invention is a known substance as described in, for example, Journal of Chemical Society (J. Chem. Soc., 1954, 678). is there.

Further, as an optically active secondary alcohol as a raw material, there are literature (J. Chem. Soc.
99,45 (1911)) and optically active 2-butanol, optically active 2-pentanol, optically active 2-hexanol, optically active 2-heptanol, optically active 2- Examples include octanol, optically active 2-nonanol, optically active 2-decanol, optically active 2-undecanol, and optically active 2-dodecanol, but preferably optically active 2-butanol, optically active 2-pentanol, optically active 2-octanol. And more preferably optically active 2-octanol.
Needless to say, the absolute configuration of the optically active alcohol can be used for both the (R) and (S) forms.

[Operation of the invention]

The compound of the present invention is very useful as an intermediate in the production of an optically active liquid crystal compound.

The compound of the present invention has an optically active group in the molecule,
It is particularly useful as an intermediate in the production of ferroelectric liquid crystals and chiral nematic liquid crystals.

Further, by introducing the compound of the present invention into a polymer liquid crystal, a polymer liquid crystal exhibiting an electro-optical effect can be produced.

〔The invention's effect〕

The compound produced by using the compound of the present invention as an intermediate product becomes a very excellent ferroelectric liquid crystal, and the ferroelectric liquid crystal has a large spontaneous polarization and is very optically and chemically stable.

In general, a liquid crystal compound has a rod-like structure composed of a nucleus portion including a benzene ring, a heterocyclic ring, a cyclohexane ring and the like, and an alkyl chain and the like. It is well known that those having an alkyl chain having a certain number of carbon atoms or more tend to show a smectic phase.

That is, the compound represented by the general formula (I) can be prepared by, for example, alkylcarboxylic acid, alkoxycarboxylic acid, 4-alkylbenzoic acid, 4-alkoxybenzoic acid, 4-alkylcarbonyloxybenzoic acid, 4-alkoxycarbonylbenzoic acid, 4-alkoxycarbonyloxybenzoic acid, 6
-Alkyl-naphthalene-2-carboxylic acid, 6-alkoxy-naphthalene-2-carboxylic acid, 6-alkylcarbonyloxy-naphthalene-2-carboxylic acid, 6-alkoxycarbonyl-naphthalene-2-carboxylic acid, 6-
Alkoxycarbonyloxy-naphthalene-2-carboxylic acid, 4- (4'-alkylphenyl) benzoic acid, 4-
(4'-alkoxyphenyl) benzoic acid, 4- (4'-
Alkylcarbonyloxy) benzoic acid, 4- (4'-alkoxycarbonyl) benzoic acid, 4- (4'-alkoxycarbonyloxy) benzoic acid, trans-4- (4 '
-Alkylphenyl) cyclohexylcarboxylic acid, trans-4- (4'-alkoxyphenyl) cyclohexylcarboxylic acid, trans-4- (4'-alkylcarbonyloxyphenyl) cyclohexylcarboxylic acid, trans-4- (4'-alkoxycarbonyl) Phenyl) cyclohexylcarboxylic acid, trans-4- (4'-alkoxycarbonyloxyphenyl) cyclohexylcarboxylic acid, 4- (trans-4'-alkylcyclohexyl) benzoic acid, 4- (5'-alkylpyrimidine-2-
Il) benzoic acid, 4- (5′-alkoxypyrimidine)
2-yl) benzoic acid, 4- (trans-5'-alkyl-1,3-dioxan-2-yl) benzoic acid, 4- (trans-5'-alkyl-1,3-dithiaoxan-2-yl) Benzoic acid, 4- (trans-5'-alkyl-1,3)
-Dithian-2-yl) benzoic acid, 4- (5'-alkyl-1,3,2-dioxaborinan-2-yl) benzoic acid,
Or a halogen atom, a cyano group, a nitro group, a methyl group on the ring of the benzene ring or naphthalene of these compounds,
A very useful ferroelectric liquid crystal can be obtained by reacting with a derivative having an ethyl group substituted.

For example, the compound (I) of the present invention and 4-alkylbenzoic acid, 4-alkoxybenzoic acid or 3-halogeno-4.
A compound of general formula (II) prepared from alkoxybenzoic acid (In the formula, R ₁ is an alkyl group or an alkoxy group having 1 to 20 carbon atoms, R ₂ is an alkyl group having 2 to 10 carbon atoms, X is a hydrogen atom or a halogen atom, and * is an asymmetric carbon atom. .) Shows a chiral smectic C phase in a temperature range relatively close to room temperature as shown in Table 2, and has a very large spontaneous polarization. That is, in Table 2, specific examples
It was found that the spontaneous polarization of the compound represented by 20 was as high as 87 _n C / cm ² and the response speed was as fast as 20 μsec.

In Table 2, C is the crystalline phase, Sc ^* is the chiral smectic C.
Phase, SA is a smectic A phase, I is an isotropic liquid, the mark of each phase and the number to the right of it indicate the transition temperature from that phase to the phase on the right, and the-mark does not indicate that phase. Means The value in the parentheses is the monotropic phase transition temperature. The value of spontaneous polarization was obtained at a temperature 10 ° C lower than the Sc ^* -SA transition temperature.

[Examples] The present invention will be specifically described below with reference to Examples, but the gist and scope of the present invention are not limited to these Examples.

Example 1 (R) -6-hydroxynaphthalene-2-carboxylic acid-
Production of 1'-methylheptyl ester (i) Production of 6-benzyloxynaphthalene-2-carboxylic acid.

100 g of 2,6-hydroxynaphthalenecarboxylic acid and 70 g of 85% potassium hydroxide were dissolved in 100 ml of water and 700 ml of ethanol, 110 g of benzyl bromide was added, and the mixture was heated under reflux for 8 hours. Then add another 35g of potassium hydroxide, 5
Heating under reflux was continued for hours. After cooling to room temperature, it was acidified with concentrated hydrochloric acid and the precipitated solid was filtered off. In addition, water, ethanol,
It was washed in order of benzene to obtain the desired product. This was used in the next reaction without further purification.

(Ii) Production of 6-benzyloxynaphthalene-2-carboxylic acid chloride Compound 6-benzyloxynaphthalene-2 obtained in (i)
-65 g of carboxylic acid was heated under reflux with 30 ml of thionyl chloride in 50 ml of toluene for 3 hours, and excess thionyl chloride and toluene were distilled off under reduced pressure to obtain an acid chloride. This crude product was used in the next reaction without purification.

(Iii) (R) -6-benzyloxynaphthalene-2-
Production of carboxylic acid -1'-methylheptyl ester The acid chloride obtained in (ii) was dissolved in 100 ml of toluene, and 30 g of (R) -2-octanol was added to this solution.
The solution dissolved in was added and left at room temperature for 8 hours. After the precipitated pyridine hydrochloride was filtered off, the organic layer was washed with 2N-hydrochloric acid, further washed with 2N-sodium hydroxide aqueous solution, and further washed with water until it became neutral.

The organic layer was separated, and toluene was distilled off under reduced pressure to obtain 80 g of an ester compound, melting point 69.5 to 71.0 ° C.

The elemental analysis values were in good agreement with the theoretical values as follows.

Theoretical value (C ₂₆ H ₃₀ O ₃ as) analysis C 79.96% C 78.89% H 7.74 % H 7.70% (iv) obtained in (iii) (R) -6- benzyloxy-2-carboxylic acid -1 30 g of'-methylheptyl ester were hydrogenated in 200 ml of ethanol at 40 ° C. in the presence of 5% palladium / 4 g of carbon at atmospheric pressure. After the palladium / carbon is filtered off, the solvent is distilled off under reduced pressure to obtain the desired (R)
-6-hydroxynaphthalene-2-carboxylic acid-1'-
23 g of methylheptyl ester was obtained. Melting point 67-68 ° C. The elemental analysis values were in good agreement with the theoretical values as shown in Table 3.

Examples 2 to 9 According to the method described in (iii) of Example 1, except that various optically active 2-alkanols were used instead of (R) -2-octanol in (iii) of Example 1. Of optically active 6-benzyloxynaphthalene-2-carboxylic acid-1'-methylalkyl ester was prepared.

Furthermore, in (iv) of Example 1, instead of (R) -6-benzyloxynaphthalene-2-carboxylic acid-1'-methylheptyl ester, various optically active 6-benzyloxynaphthalene-2-carboxylic acid-1 'was used. Various optically active 6-hydroxynaphthalene-2-carboxylic acid-1'-methylalkyl esters were produced according to the method described in (iv) of Example 1 except that -methylalkyl ester was used.

The elemental analysis values of these compounds were in good agreement with the theoretical values as shown in Table 3.

Claims (1)

[Claims] 1. A general formula (I) (In the formula, R represents an alkyl group having 2 to 10 carbon atoms, and * represents an asymmetric carbon atom).