JPS59118752A - Cyanocyclohexane derivative - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R is H or 1-10C alkyl). EXAMPLE:trans-4-[trans-4''-Pentylcyclohexyl)phenyl]cyanocyclohexane. USE:A liquid crystal composition having high liquid crystal-clear point (N-I point) and broad nematic temperature range, and neverthless of low viscosity. PROCESS:The compound of formula I can be prepared by (1) reducing the compound of formula II with metallic sodium in isoamyl alcohol, (2) converting the resultant compound of formula III to the acid chloride of formula IV with thionyl chloride, (3) reacting with ammonia to obtain an amide, and (4) subjecting the amide to dehydration reaction with thionyl chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal material exhibiting a liquid crystal phase over a wide temperature range and having positive dielectric anisotropy, and a liquid crystal composition containing the same.

Display elements using liquid crystals have come to be widely used in watches, calculators, etc. This liquid crystal display element utilizes the properties of optical anisotropy and dielectric anisotropy of liquid crystal materials, and liquid crystal phases include nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase, among which nematic liquid crystal is used. The one that has been put into practical use is the most widely used. Furthermore, there are TN (twisted nematic) types, DB (dynamic scattering) types, guest-host types, DAP types, etc., and the properties required of the liquid crystal materials used for each type are different.

However, in any case, it is desirable that the liquid crystal materials used in these display elements exhibit a liquid crystal phase over as wide a range of natural temperatures as possible, but there is currently no single material that satisfies these conditions. Currently, materials that can be put to practical use are obtained by mixing several types of liquid crystal substances or non-liquid crystal substances. In addition, these substances must of course be stable against moisture, light, heat, air, etc., and the required threshold voltage and saturation voltage for driving the display element must be as low as possible, and the response speed must be as low as possible. In order to speed up the process, it is desirable that the viscosity be as low as possible. By the way, in order to widen the liquid crystal temperature range toward higher temperatures, it is necessary to use a liquid crystal substance with a high melting point as a component, but liquid crystal substances with a high melting point generally have a high viscosity, so the liquid crystal composition containing it also has a high viscosity. As a result, the response speed of liquid crystal display elements that can be used at high temperatures, for example, up to about 80° C., particularly at low temperatures, tends to be significantly slow. However, the present inventors have found a liquid crystal material that has a high liquid crystal clearing point (N-1 point) and a wide natural temperature range and has a low viscosity, and has arrived at the present invention.

That is, the present invention relates to trans-4-(4'-()trans-41
-alkylcyclohexyl)phenylcocyanocyclohexane and a liquid crystal composition containing the same.

The compounds of the present invention have a high clearing point, for example the 0-N point of trans-4-r,,4'-()trans-41-pentylcyclohexyl)phenylcocyanocyclohexane, which is - of the compound of the present invention. It exhibits a liquid crystal phase over a wide temperature range of 123.1°C and 181.1°C at the N-1 point, and by adding it as a component of the liquid crystal composition, the clearing point can be lowered without increasing the viscosity of the liquid crystal composition. can be raised. Further, although the dielectric anisotropy value of the compound of the present invention is approximately +1, the threshold voltage and saturation voltage of the 5 compositions do not change much.

It also has good stability against moisture, heat, light, etc. Furthermore, the optical anisotropy value Δn of the compound of the present invention is small, and it can be applied to display cells that take advantage of this property.

Next, a method for producing the compound of the present invention will be described. First, 4'-()
Lance-4#-furkylcyclohexyl)biphenyl-
4-carboxylic acid was reduced with metallic sodium in isoamyl alcohol to give trans-4-(4'-()trans-4
1-Alkylcyclohexyl)phenylcocyclohexanecarboxylic acid l11. get. Next, this is converted into an acid chloride with thionyl chloride, and then reacted with ammonia to form an amide, which is dehydrated with thionyl chloride to obtain the desired trans-4-(4'-()trans-4#-alkylcyclohexyl). Phenylcocyanocyclohexane was produced.

If the above is expressed as a chemical formula, (R is the same as above) The present invention will be explained in more detail with reference to Examples below.

Example 1 [Trans-4-(4,'-() Lance-41
- Production of trans-4-(4'-()trans-4'-pentylcyclohexyl)phenylcocyclohexanecarboxylic acid] (1) Production of trans-4-(4'-()trans-4'-pentylcyclohexyl)phenylcocyclohexanecarboxylic acid 4'-()trans-41-hentyl Stir 10V of (cyclohexyl)biphenyl-4-carboxylic acid with 2'500m of isoamyl alcohol and heat to 9QC. When 30f of metallic sodium is added, it begins to violently rebel. While continuing to reflux, an additional 1,202 ml of sodium metal was added over a period of 3 hours, and the reaction solution gradually became homogeneous.

After the reaction is completed, it is allowed to cool to 100'C. Next, the isoamyl alcohol is distilled off while adding trap water. Water is 2000
m added. Then add 6N hydrochloric acid to 21117II to make it completely acidic. The deposited precipitate is filtered and washed with water. The product was recrystallized from acetic acid to obtain trans-4-(4'-)trans-41-pentylcyclohexyl)phenylcyclohexanecalfone/1&4.5F. This carboxylic acid also exhibits liquid crystallinity and its C-8 point is 239.1'C.

S-1 point is 274.3°C (decomposition).

(2) Trans-4-1, C-()trans- produced by cyanation (1)
41-pentylcyclohexyl)f,=C=]cyclohexanecarboxylic acid 1 t to thionyl chloride 3ONI
Heat to 80'C with t. The reaction solution became homogeneous in 2 hours, and the reaction was continued for an additional 5 hours. Excess thionyl chloride is distilled off under reduced pressure. The oil that remains is the acid chloride. This oil is added to 100 m of concentrated aqueous ammonia with vigorous stirring.

After stirring for 1 hour, the precipitate formed is filtered.

Air-dry the solid and put the entire amount into a flask and add thionyl chloride L.
Heat to reflux with oom.

It becomes almost uniform in 4 to 5 hours. Excess thionyl chloride is then distilled off under reduced pressure. Add 10% of the remaining oil to toluene.
Dissolve at 0 dK and wash the toluene layer three times with 2N-NaOH and then with water until neutral. After drying with anhydrous sodium sulfate, it is passed through an activated alumina column. After concentrating the eluate, the remaining oil was recrystallized twice from ethanol to obtain the desired trans-4-(4'-()trans-41-pentylcyclohexyl)phenylcocyanocyclohexane. Condition: 0.2 t, yield: 21%. Its C-N point is 123.1
~124.8°C, N-1 point is 1 B 1. It was IC. Furthermore, it was confirmed by infrared absorption spectrum and NMR that this compound was the target compound.

Example 2 (use example) trans-4-propyl-(4/-cyanophenyl)cyclohexa 7 28% trans-4-pentyl-(4'-cyanophenyl)cyclohexane 42% trans-4-hegthyl-(4'- The N-1 point of a liquid crystal composition having a composition of 30% (cyanophenyl)cyclohexane is 52°C. Threshold voltage fd1.53 of this liquid crystal composition sealed in a TN cell (twisted nematic cell) with a cell thickness of 10 μm
v, the saturation voltage was 2.12 VT. The viscosity was 23 cp at 20C, and the optical anisotropy value was 0.120.

To 90 parts of this liquid crystal composition was added the transformer produced in Example 1.
The N-1 point of the liquid crystal composition to which 10 parts of 4-(4'-()lans-4'-pentylcyclohexyl)phenyl]anocyclohexane was added rose to 63°C. The threshold voltage measured in the same manner as above was 1.55V, and the saturation voltage #'i was 2.14V. Also, the viscosity is 24C at 20℃
p, and the optical anisotropy value was 0.120, which was almost unchanged.

that's all

Claims (2)

[Claims] (1) Trans-4-[4'-(trans-4'
-Furkylcyclohexyl]phenyl]cyanocyclohexane. (2) trans-4-(4'-()uy-4' represented by the general formula (in the above formula, R represents hydrogen or an alkyl group having 1 to 1 carbon atoms)
A liquid crystal composition comprising at least one type of -'T-rukylcyclohexyl)phenylconanocyclohexane.