JP3506257B2 - Difluorocyclopropane derivative - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel compound which is a difluorocyclopropane derivative useful as an electro-optical liquid crystal display material.

[0002]

2. Description of the Related Art Liquid crystal display devices have come to be used in watches, calculators, various measuring instruments, automobile panels, word processors, electronic notebooks, printers, computers, televisions and the like. Typical liquid crystal display methods are TN (twisted nematic) type, STN (super twisted nematic) type, DS (dynamic light scattering) type, GH (guest host) type, and FLC (ferroelectric liquid crystal). ) And the like are known, of which the TN type and the STN type are most widely used at present. Also, as the drive system, the conventional static drive has become more common, and the multiplex drive has become more common, and the simple matrix system and recently the active matrix system have been put into practical use. Of these, the active matrix method can display the highest image quality, has a wide viewing angle, facilitates high definition and colorization, and can also display moving images. Is believed to be.

The liquid crystal material used in this active matrix display system is required to have various characteristics as in the case of a normal liquid crystal display. In particular, (1) it has a high specific resistance and an excellent voltage holding ratio, (2) Threshold voltage (V
It is important that _th ) is low, and (3) the temperature range is wide.

Normally, the threshold voltage in liquid crystal display is expressed by the equation (1)

[0005]

[Equation 1]

(In the formula, k is a proportional constant, K is an elastic constant, and Δε is a dielectric anisotropy, respectively.) As can be seen from this formula, in order to lower the threshold voltage. Must reduce the elastic constant or increase the dielectric anisotropy.

However, a liquid crystal compound having a large dielectric anisotropy has a large polarity, and it is quite difficult to obtain a high specific resistance value and a high voltage holding ratio. Therefore, a liquid crystal material having a small elastic constant is required for such purpose.

However, many bicyclic compounds having a small elastic constant tend to significantly lower the maximum temperature of the liquid crystal phase of the composition. On the other hand, in order to extend the temperature range of the liquid crystal phase of the liquid crystal composition to a particularly high temperature range, it is necessary to add a compound having a high maximum temperature of the tricyclic or tetracyclic liquid crystal phase to the composition. However, many compounds with a high maximum temperature like this have large elastic constants,
When added, it tends to increase the threshold voltage of the composition. Therefore, it was quite difficult to obtain a liquid crystal composition having a low dielectric constant anisotropy, a wide temperature range of a liquid crystal phase up to a high temperature range, and a low threshold voltage.

[0009]

The problem to be solved by the present invention is to provide a compound for expanding the temperature range of a liquid crystal phase to a high temperature range without increasing the threshold voltage of the composition, and It is intended to provide a liquid crystal composition containing the compound, having a wide temperature range of a liquid crystal phase and a low threshold voltage.

[0010]

In order to solve the above-mentioned problems, the present invention has the general formula (I)

[0011]

[Chemical 2]

(In the formula, R ¹ represents a straight chain alkyl group having 1 to 10 carbon atoms, preferably a straight chain alkyl group having 1 to 5 carbon atoms, particularly preferably a propyl group, and R ²
Represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and a methyl group is particularly preferable. When R ² is an alkyl group, the cyclopropane ring is preferably in the trans configuration. The cyclohexane ring has a trans configuration. ) The difluoro cyclopropane derivative represented by these is provided.

The compound of the general formula (I) of the present invention can be obtained, for example, by the following production method.
First, the general formula (II)

[0014]

[Chemical 3]

(Wherein R ¹ has the same meaning as in formula (I) and the cyclohexane ring has the trans configuration) and the cyclohexylphenol derivative represented by formula (III)

[0016]

[Chemical 4]

(Wherein R ² has the same meaning as in formula (I) and X represents a chlorine atom, a bromine atom, an iodine atom or a leaving group such as a sulfonic acid ester). By condensing the derivative under basic conditions, the compound of general formula (IV)

[0018]

[Chemical 5]

An allyloxybenzene derivative represented by the formula: wherein R ¹ and R ² have the same meanings as in formula (I) and the cyclohexane ring has a trans configuration is obtained. The compound of general formula (I) can be easily obtained by reacting the compound of general formula (IV) with chlorodifluoroacetate salt to form difluorocyclopropane. At this time, in the case of a compound in which R ² is an alkyl group, a trans-form compound of the general formula (I) is obtained from a trans-formula compound of the general formula (III), and a cis-form compound of the general formula (III) is obtained. Gives a cis compound of formula (I).

The allyl halide derivative of the general formula (III) in the trans form corresponds to the corresponding general formula (V)

[0021]

[Chemical 6]

(Wherein R ² has the same meaning as in formula (I)), the propargyl alcohol derivative is reduced with sodium metal in liquid ammonia, and the obtained allyl alcohol derivative is halogenated. Alternatively, it can be obtained by sulfonic acid esterification.

The allyl halide derivative of the general formula (III) in cis form is subjected to catalytic reduction of the corresponding propargyl alcohol derivative of the general formula (V) in a hydrogen atmosphere, and the obtained allyl alcohol derivative is halogenated or sulfonated. Can be obtained by doing.

Representative examples of the compound represented by the general formula (I) thus produced are shown in Table 1.

[0025]

[Table 1]

(In the table, Cr represents a crystalline phase and I represents an isotropic liquid phase.)

From Table 1, many of the compounds represented by the general formula (I) do not show a nematic phase by themselves. However, as shown in Examples described later, when added to the composition, the temperature range of the liquid crystal phase can be expanded to a high temperature range.

The compound represented by the general formula (I) of the present invention is used as a material of a field effect display cell such as TN type or STN type in a state of being mixed with another nematic liquid crystal compound, and is used as a threshold of the composition. It can be used for the purpose of expanding the temperature range of the liquid crystal phase to a high temperature range without increasing the value voltage, and is particularly suitable as a constituent component of an active matrix driving liquid crystal material.

Preferred representative examples of the nematic liquid crystal compound which can be used by mixing with the compound represented by the general formula (I) of the present invention are, for example, 4-substituted benzoic acid 4-substituted phenyl ester and 4-substituted benzoic acid. Cyclohexanecarboxylic acid 4-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted biphenylyl ester, 4
4- (4-Substituted cyclohexanecarbonyloxy) benzoic acid 4-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4-substituted phenyl ester, 4- (4
-Substituted cyclohexyl) benzoic acid 4-substituted cyclohexyl ester, 4,4'-substituted biphenyl, 1- (4-substituted phenyl) -4-substituted cyclohexane, 4,4 "-substituted terphenyl, 1- (4'-substituted Biphenylyl) -4
-Substituted cyclohexane, 1- (4-substituted cyclohexyl) -4- (4-substituted phenyl) cyclohexane, 2-
(4-Substituted phenyl) -5-substituted pyrimidine, 2-
(4'-substituted biphenylyl) -5-substituted pyrimidine and the like can be mentioned, and particularly for active matrix, 4,4'-substituted biphenyl, 1- (4-substituted phenyl) -4-substituted cyclohexane, 4, 4 "-substituted terphenyl, 1- (4'-substituted biphenylyl) -4-substituted cyclohexane, 1- (4-substituted cyclohexyl)-
4- (4-substituted phenyl) cyclohexane and the like are preferable.

The effects of the compound of the general formula (I) are shown in the examples described below, but are clear from the following examples, for example. A matrix liquid crystal (A) currently widely used as a nematic liquid crystal material

[0031]

[Chemical 7]

(In the above, the cyclohexane ring represents the trans configuration and "%" represents "% by weight") was prepared. This host liquid crystal (A) exhibits a nematic phase at 54.5 ° C. or lower, and has a dielectric anisotropy (Δε) of 6.7, and a threshold voltage (V _th ) of a TN cell manufactured using this. Was 1.60V.

A liquid crystal composition (M-1) comprising 80% by weight of the base liquid crystal (A) and 20% by weight of the compound (No. 1) in Table 1 was prepared. The upper limit temperature of the nematic phase of (M-1) was significantly increased to 67.1 ° C, and Δε was 6.
It was 05. When a cell was produced in the same manner using this composition, V _th was 1.70 V, which was not very high, although Δε was lowered.

On the other hand, instead of the compound of (No. 1), a compound of the formula (R-1) having a structure similar to that of the compound of (No. 1) but having no difluorocyclopropane ring.

[0035]

[Chemical 8]

20% by weight of the compound of and the host liquid crystal (A) 8
A liquid crystal composition (N-1) consisting of 0 wt% was prepared. The upper limit temperature of the nematic phase of (N-1) was 76.2 ° C, which was considerably higher than that of (M-1). However, when a cell was prepared in the same manner, V _th was 1.99 V, which was significantly higher than that of (M-1). Since Δε is 6.1 and about the same as (M-1), the elastic constant of the compound of formula (R-1) is considered to be considerably large.

Next, in place of the compound (No. 1),
A compound of the formula (R-2) having a structure similar to that of the compound of (No. 1) but having a different position of the difluorocyclopropane ring.

[0038]

[Chemical 9]

20% by weight of the compound of and the host liquid crystal (A) 8
A liquid crystal composition (N-1) consisting of 0 wt% was prepared. When a cell was prepared in the same manner, V _th was 1.45 V, which was lower than that of (M-1), and Δε was 6.1 (M-1).
It was about the same. However, the maximum temperature of the nematic phase was 53.0 ° C., which was significantly lower than that of (M-1) and lower than that of the host liquid crystal (A).

From the above, the addition of the compound represented by the general formula (I) of the present invention causes almost no increase in the threshold voltage (V _th ) of the nematic liquid crystal composition and the temperature range of the liquid crystal phase. It is clear that can be effectively expanded.

[0041]

The present invention will be further described below by showing Examples of the present invention. However, the invention is not limited to these examples.

The phase transition temperature was measured by using a polarizing microscope equipped with a temperature adjusting stage and a differential scanning calorimeter (DSC). Further, the structure of the compound has a nuclear magnetic resonance spectrum ( ¹ H-NMR) and an infrared absorption spectrum (I
R), mass spectrum (MS), etc. IR
(KBr) represents the measurement by tableting. N
CDCl _{3 in} MR represents a solvent, d is a doublet,
m represents a multiple line. Further, J represents a coupling constant. M ^{+ in} MS represents the parent peak.

(Example 1) trans-3-methyl-
2,2-Difluoro-1- [4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyloxymethyl] cyclopropane (No. 1
Compound)

[0044]

[Chemical 10]

7.5 g of 4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -1- (trans-2-oxybenzene was dissolved in 23 ml of diethylene glycol dimethyl ether, and this solution was heated to 165 ° C. A solution of 19.9 g of sodium difluorochloroacetate in 52 ml of diethylene glycol dimethyl ether was added to this while maintaining the internal temperature at 160 ° C or higher.
It was dripped in 0 minutes. After stirring for another 2 hours at 165 ° C,
After allowing to cool, the reaction solution was poured into water, and the reaction product was extracted with toluene. The organic phase is dried over anhydrous magnesium sulfate, concentrated, and then purified by silica gel column chromatography (hexane) to give trans-3-methyl-2,2.
-6.2 g of white crystals of difluoro-1- [4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyloxymethyl] cyclopropane
Got Further, it was recrystallized from ethanol for purification, and its phase transition temperature was measured. As a result, the melting point was 168 ° C.

IR (KBr): 1515, 1485, 1
450, 1395, 1260, 1245, 1225, 1
195, 1180, 1025, 830, 805 cm ^-1 NMR: δ = 0.8 to 1.8 (m, 31H), 2.1 to
2.6 (m, 1H), 4.0 (d, 2H, J = 7.
0), 6.8 (d, 2H, J = 8.8), 7.1 (d,
2H, J = 8.8) MS: m / e = 394 (M ⁺ ).

Example 2 Preparation of Liquid Crystal Composition (1)

[0048]

[Chemical 11]

(Among the above, the cyclohexane ring represents the trans configuration and "%" represents "% by weight".) A matrix liquid crystal (A) was prepared, and a nematic (N) phase was obtained at 54.5 ° C or lower. showed that. The physical properties and the threshold voltage (V _th ) of the TN cell manufactured using the same were as follows.

Dielectric anisotropy (Δε) 6.7 Refractive index anisotropy (Δn) 0.092 Threshold voltage (V _th ) 1.60 V

A liquid crystal composition (M-1) comprising 80% by weight of the base liquid crystal (A) and 20% by weight of the compound (No. 1) of Example 1 was prepared. The upper limit temperature (T _NI ) of the N phase of (M-1) and its physical properties were as follows.

Maximum temperature of N phase (T _NI ) 67.1 ° C. Dielectric anisotropy (Δε) 6.1 Refractive index anisotropy (Δn) 0.094 Threshold voltage (V _th ) 1.70 V

As described above, it is understood that the upper limit temperature of the nematic phase is significantly increased although the threshold voltage is slightly increased. Dielectric anisotropy (Δ
Since ε) is small, the elastic constant (K) of the compound of (No. 1) is considered to be quite small in view of the above formula (1).

When this composition (M-1) was left at a low temperature for a long time, no precipitation or the like was observed. Therefore, it is clear that the compound (No. 1) is also excellent in compatibility with conventional liquid crystal compounds.

Comparative Example 1 In Example 2, (No.
Instead of the compound of 1), a compound of the formula (R-1) having a structure similar to that of the compound of (No. 1) but having no difluorocyclopropane ring.

[0056]

[Chemical 12]

20% by weight of the compound of and the host liquid crystal (A) 8
A liquid crystal composition (N-1) consisting of 0 wt% was prepared. The upper limit temperature (T _NI ) of this N phase of (N-1) and its physical properties were as follows.

Maximum temperature of N phase (T _NI ) 76.2 ° C. Dielectric anisotropy (Δε) 6.1 Refractive index anisotropy (Δn) 0.100 Threshold voltage (V _th ) 1.99V

As described above, although the upper limit temperature of the N phase was considerably higher than that of the base liquid crystal (A), the threshold voltage (V _th ) was 1.99 V, which was significantly higher than that of (M-1). Since the dielectric anisotropy (Δε) is not different from that of (M-1), the elastic constants of the compounds of the above formulas (1) to (R-1) are considerably larger than those of the compound of (No. 1). it is conceivable that.

Comparative Example 2 In Example 2, (No.
In place of the compound of 1), a compound of formula (R-2) having a similar structure to the compound of (No. 1) but having a different difluorocyclopropane ring position.

[0061]

[Chemical 13]

20% by weight of the compound of and the host liquid crystal (A) 8
A liquid crystal composition (N-1) consisting of 0 wt% was prepared. The upper limit temperature (T _NI ) of this N phase of (N-1) and its physical properties were as follows.

Maximum temperature of N phase (T _NI ) 53.0 ° C. Dielectric anisotropy (Δε) 6.1 Refractive index anisotropy (Δn) 0.090 Threshold voltage (V _th ) 1.45 V

Thus, the threshold voltage (V _th ) is 1.
Although it was 45 V, which was lower than that of (M-1), the upper limit temperature of the N phase was slightly lower than that of the host liquid crystal (A), and (M-
The value was considerably lower than that of 1). Since the dielectric anisotropy (Δε) of (N-1) does not change from that of (M-1), the elastic constant of the compound of formula (R-2) is also (No. It is considered to be considerably larger than the compound of 1).

From the above, by adding a small amount of the compound of the general formula (I) to the nematic liquid crystal composition,
It is clear that the upper limit temperature of the nematic liquid crystal phase can be effectively increased without increasing the threshold voltage (V _th ).

[0066]

INDUSTRIAL APPLICABILITY The compound represented by the general formula (I) of the present invention can be easily produced industrially, is chemically stable to heat, light, water and the like, and is widely used as a nematic liquid crystal at present. It is also excellent in compatibility with existing nematic liquid crystal compositions. Moreover, by adding a small amount to the nematic liquid crystal composition, the temperature range of the liquid crystal phase can be expanded without increasing the threshold voltage (V _th ). Therefore,
It is very useful as various liquid crystal display elements which have a wide temperature range and are required to be driven at a low voltage, especially as a liquid crystal material for active matrix driving.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C07C 43/225 C07C 41/16 C09K 19/30 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A compound represented by the general formula (I): (In the formula, R ¹ represents a linear alkyl group having 1 to 10 carbon atoms, and R ² represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms). 2. A liquid crystal composition containing the compound represented by formula (I) according to claim 1.