JPH0247986B2 - HAROGENCHIKANJESUTERU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel liquid crystal compound having weak negative dielectric anisotropy useful as a component of a liquid crystal composition, and a liquid crystal composition containing the same. Display elements using liquid crystals have come to be widely used in watches, calculators, etc. These liquid crystal display elements are divided into TN type (twisted nematic type), DS type (disturbance scattering type), guest-host type, DAP type, dual frequency method type, etc. depending on the liquid crystal display method, and are used depending on each type. The characteristics of the liquid crystals used are different, but all of them are required to have a large absolute value of dielectric anisotropy. This is because by using a liquid crystal composition with a large absolute value of dielectric anisotropy, the driving voltage of the display element can generally be lowered and the response characteristics can be improved. However, if there is a liquid crystal that can be driven at a low voltage even if the absolute value of dielectric anisotropy is not large, the power consumption of the display element can be further reduced, which would be even more preferable. As a result of extensive research into compounds having such characteristics, the present inventors discovered that certain halogen-containing compounds satisfy such requirements, and arrived at the present invention. That is, the present invention is based on the general formula (In the above formula, R represents an alkyl group or an alkoxy group having 1 to 10 carbon atoms,

【ceremony

[Formula] or

[Production of 2-chloro-4-(trans-4-propylcyclohexanoyloxy)benzoic acid-2-chloro-4-fluorophenyl ester]

100 g of 2-chloro-4-hydroxybenzoic acid and 100 g of 2-chloro-4-fluorophenol
Place in a 3-necked flask and attach a stirrer and water meter. Add 1.5 xylene, 20 g of boric acid,
Add 10 ml of sulfuric acid and reflux. Continue until no more water is distilled into the water meter. It took 20 hours.
After cooling, crystals will precipitate, so separate the 2-chloro-
4-hydroxybenzoic acid-2-chloro-4-fluorophenyl ester was obtained. Melting point 110-130℃,
The yield was 45 g, and the yield was 27%. Next, this 2-chloro-4-hydroxybenzoic acid-2-chloro-4-fluorophenyl ester
3.0 g (0.01 mol) was dissolved in 20 ml of pyridine, and then 1.9 g (0.011 mol) of trans-4-propylcyclohexanecarboxylic acid chloride was added for reaction. After the reaction, add 50ml of toluene and leave it overnight, then add water.
Pour into 100ml. Separate the toluene layer and 6N−
After extracting three times with HCl and three times with 2N-NaOH, the toluene layer is washed with water until it becomes completely neutral, and then the toluene layer is distilled off under reduced pressure to leave crystals. It was recrystallized from ethanol to obtain the desired 2-chloro-4-(trans-4-propylcyclohexanoyloxy)benzoic acid-2-chloro-
4-Fluorophenyl ester was produced. The C-N point of this product is 116.0 to 119.4℃, and the N-I point is
The temperature was 152.0°C, the yield was 1.2 g, and the yield was 27%. It was confirmed to be the desired product by elemental analysis and NMR spectrum. Examples 2 to 7 The 2-chloro- 4-hydroxybenzoic acid-2-chloro-4-
Ester derivatives of fluorophenyl esters were prepared. These physical property values are shown in Table 1 together with the results of Example 1.

【table】

[Table] Example 8 (Usage example) 4-pentyl-4'-cyanobiphenyl 45% 4-heptyl-4'-cyanobiphenyl 29% 4-octyloxy-4'-cyanobiphenyl
The liquid crystal mixture (A) with the composition 15% 4-pentyl-4''-cyanoterphenyl 11% has an N-I point of 63.3°C, a dielectric anisotropy of +12.4, and a viscosity of 46 cp at 20°C. The mixture (A) is sealed in a 10 μm thick cell assembled with a substrate equipped with a tin oxide transparent electrode coated with silicon and rubbed to form a display element.
When the characteristics were measured at 25℃, the threshold voltage was
The voltage was 1.65V, and the saturation voltage was 2.31V. 80 parts of this liquid crystal mixture (A) and 2-chloro-4 of Example 1 of the present invention
The N-I point of the mixture with 20 parts of -(trans-4-propylcyclohexanoyloxy)benzoic acid-2-chloro-4-fluorophenyl ester is 67.6.
℃, dielectric anisotropy is +10.5, viscosity is 25℃
However, when measured under the same conditions, the threshold voltage was 1.65V and the saturation voltage was 2.30V, almost unchanged.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group or an alkoxy group having 1 to 10 carbon atoms, and [Formula] represents [Formula] or [Formula]) 2-chloro-4-hydroxybenzoic acid-2-chloro - Ester derivative of 4-fluorophenyl ester. 2 General formula (In the above formula, R represents an alkyl group or an alkoxy group having 1 to 10 carbon atoms, and [Formula] represents [Formula] or [Formula]) 2-chloro-4-hydroxybenzoic acid-2-chloro - A liquid crystal composition comprising at least one ester derivative of 4-fluorophenyl ester.