JPS59172452A - Optically active substance having negative dielectric anisotropic value - Google Patents

Abstract

NEW MATERIAL:An optically active liquid crystal substance shown by the formula I (R is 1-10C alkyl; n is 0 or 1; * is asymmetric carbon). EXAMPLE:S-( + )- Trans-4-[ 4-( 2-methylbutyloxy ) phenyl ] cyclohexane - carboxylic acid-2-cyano-4-heptylphenyl ester. USE:A liquid crystal composition for display element of cholesteric nematic phase transition type. Having spiral molecular structure, showing mostly cholesteric phase, or having negative dielectric anisotropy. PREPARATION:A compound shown by the formula II is reacted with metal sodium in isoamyl alcohol to give a compound shown by the formula III, which is reacted with SOCl2 to give an acid chloride shown by the formula IV. This compound is further reacted with 2-cyano-4-alkylphenol in the presence of pyridine, to give a compound shown by the formula I .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal compound having negative dielectric anisotropy, optically active, and a helical molecular structure, and a liquid crystal composition containing the same.

Liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy that are the characteristics of liquid crystal materials, and there are various display types, but the one currently in practical use is the twisted nematic type (TNW). ), dynamic scattering type (DS type), etc. However, recently, other types of liquid crystal display methods have been actively developed, and representative examples include cholesteric-nematic phase transition type display and White-Taylor type color display. The liquid crystal compositions used in these display elements are each adjusted to have an appropriate cholesteric helical pitch by adding an optically active substance to a nematic liquid crystal. The molecules of the optically active substance to be added have a twisted helical structure.1. It is desired that the helical pitch be short and that it be stable against heat, light, air, and water. The compound of the present invention is a novel compound having optical activity and a twisted molecular structure, which is useful for the above-mentioned applications.

That is, the present invention is based on the general formula % (in the above formula, R is an alkyl group having 1 to 1 o carbon atoms, and n is 0
or S-(t)-trans-4-(4-(2-methylbutyl)phenylcocyclohexanecarboxylic acid-2-cyano-
4-alkylphenyl ester and S-(+-)-thone-4-(4-(2-methylbutyloxy)7-el)cyclohexanecarboxylic acid-2-cyanophenyl ester and a liquid crystal composition containing them. be.

The compounds of the present invention have a helical molecular structure, many exhibit a cholesteric phase, and also have negative dielectric anisotropy. By adding a small amount of these compounds to a nematic liquid crystal, a liquid crystal composition for a cholesteric-nematic phase transition display element or a white tailor display element can be obtained. The helical pitch of this compound itself, obtained from the helical pitch value obtained by adding 10% of this compound to a nematic liquid crystal and measuring it, is 8 for n = o in formula (1).
．． 4 μm, ng=l is 8.2 μm. Furthermore, when this compound is added to a nematic liquid crystal or composition for a TN type display element, it is possible to reduce the occurrence of striped patterns (so-called reverse domains) on the display surface and improve its performance.

Next, the method for producing the compound according to the present invention will be described. First, S-(th)-4-(2-methylbutyl)biphenylyl-4'-carboxylic acid or 1ds-f+)-4-(2-methylbutyloxy)biphenylyl -4'-carboxylic acid is reduced by the action of sodium metal in an isoamyl alcohol solvent to obtain S-(t)-tri-4-(2-methylbutylphenyl)cyclohexanecarboxylic acid or S-←)-trans-4 -(2-methylbutyloxyphenyl)cyclohexanecarboxylic acid. This is reacted with thionyl chloride to form an acid chloride, and then reacted with 2-cyano-4-alkylphenol in the presence of pyridine to obtain the desired product. This can be expressed as a chemical formula as follows.

(R, n and * in the above formula are the same as above) The present compound will be explained in more detail with reference to Examples below.

Example 1 [S-(t)-trans-4-(4-(2-methylbutyloxy)phenyl]cyclohexane) Bore f/l
-Production of 2-cyano-4-heptyl phenyl ester] (1) Production of S-(t)-trans-4-(4-(2-methylbutyloxy)phenylcocyclohexanecarboxylic acid 5-(-1-) -3 g of -4-(2-methylbutyloxy)biphenylyl-4'-carboxylic acid is stirred with inamyl alcohol 150 (lyl) and heated to 90"C. When 1 og of metallic sodium is added thereto, a violent reaction begins. While continuing to reflux, an additional 100 f of metallic sodium is added over 3 hours.The reaction solution gradually becomes homogeneous.After the reaction is complete, it is allowed to cool to 100°C.Isoamyl alcohol is distilled off while adding water little by little.

1.54 liters of water was added. After 14 hours of 6N hydrochloric acid was added to make the mixture completely acidic, the precipitate was filtered and thoroughly washed with water. This was thoroughly dried and used for the next reaction.

(2) S-←)-trans-4-(2-methylbutylphenyl)cyclohexanecarboxylic acid o, 't obtained in esterification (1)
oy into a flask with thionyl chloride 1 (1+l).
When refluxed at 0 to 70'C, it becomes uniform in about 2 hours, and after further heating for 1 hour, excess thionyl chloride is distilled off under reduced pressure, leaving the acid chloride as an oil. 2- in another flask
Dissolve 0.55 f of cyano-4-heptylphenol in 10 ml of pyridine, add the entire amount of the acid chloride, and stir at room temperature to react. Furthermore, 10 x tt of toluene was added, mixed well, and left overnight, then poured into 100 ml of water, and 20 ml of toluene was added for extraction.

The toluene layer is washed with 6N hydrochloric acid, then with 2N sodium hydroxide solution, and then with water until neutral. After drying it over anhydrous sodium sulfate, toluene was distilled off under reduced pressure, and the remaining crystals were recrystallized twice with ethanol to obtain the desired S-←
)-trans-4-(2-methylbutyloxyphenyl)cyclohexanecarboxylic acid-2-cyano-4-hebutylphenyl ester was obtained by 0.68 gJ & (yield 58%
). This substance exhibits a cholesteric liquid crystal phase, and its C-
Point I is 70.5-71.5°C.

Ch-I point was 40.5-4i, o'c. When 10% of this compound was added to a nematic liquid crystal composition and measured, the helical pitch of the compound itself calculated from the value of the helical pitch was 8.2 μm.

Example 2 S-(t)-4-(2-methylbutyloxy)biphenylyl-4'-carboxylic acid in Example 1 was replaced with S-
←)-4-(2-methylbutyl)biphenylyl-4'-
S-←)-trans-4-(4-(2-methylbutyl)phenyl]cyclohe+sancarboxylic acid-2-cyano-4-heptylphenyl ester 0.929 was produced in exactly the same manner except that carboxylic acid was used. This is also a cholesterlink liquid crystal, and its C-I point is 65.5℃, Ch-I
The point was 80.4°C. Further, the helical pitch of this compound obtained by calculation in the same manner as in Example 1 was 3.4 μm.

Compounds having R (alkyl group) other than those mentioned above in formula (1) can also be produced in the same manner by using the corresponding 2-cyano-4-alkylphenol.

S-(t)-trans-4-(4-(2-methylbutyloxy)phenylcocyclohexanecarboxylic acid-2-)
It can be seen with the naked eye that a TN cell using a liquid crystal composition containing 1 part of cyano-4-hebutylphenyl ester has a significantly reduced reverse domain compared to a TN cell manufactured without adding this compound. It was observed frequently.

Example 4 (Use Example 2) S-(T) of the present invention was added to Rixon GR-6899 part.
-Trans-4-(4-(2-methylbutyl)phenylcocyclohexanecarboxylic acid-2-Schiff/-4-heptylphenyl ester) A TN cell using a liquid crystal composition containing 1 part of this compound does not contain this compound. It was observed with the naked eye that the reverse domain was greatly reduced compared to the produced TN cell.

that's all

Claims (2)

[Claims] (1) General formula % formula % () (In the above formula, R is an alkyl group having 1 to 10 carbon atoms, and n is 0
or 1 (* indicates an asymmetric carbon atom). (2) General formula (in the above formula, R is an alkyl group having 1 to 1 o carbon atoms, n is 0
or 1, * indicates an asymmetric carbon atom) A liquid crystal composition containing at least one optically active liquid crystal substance.