1-(trifluoromethyl)naphthalene derivative

The present invention relates to a new liquid crystalline compound which has 1-(trifluoromethyl)naphthyl group useful as an electrooptic liquid crystal display material, a liquid crystal composition containing thereof, and a liquid crystal display device using it.

A liquid crystal display device is widely used now because of excellent features of low voltage operation and thin type display, and the like. A TN (Twisted Nematic), a STN (Super-Twisted Nematic), or an active matrix (TFT: thin film transistor) based on the TN, and the like are used for the display type of the conventional liquid crystal display device, which use a liquid crystal composition with a positive dielectric anisotropy value. However, narrowness of a viewing angle is one of weak points for these display types, and its improvement is a big problem with the greater demand of enlargement of a liquid crystal panel in recent years.

In order to solve this problem, display modes such as vertical alignment mode, IPS (In-Plane-Switching) and the like have newly been put into practical use in recent years. The vertical alignment mode is the mode aimed at improving the viewing angle by use of vertical orientation of liquid crystal molecules, which uses liquid crystal compositions having negative dielectric anisotropy (Δ∈). On the other hand, IPS is the method aimed at improving the viewing angle by switching the liquid crystal molecules using horizontal lateral electric field against a glass substrate, which liquid crystal composition having positive Δ∈ or negative Δ∈ is used. Thus, the liquid crystal compound and liquid crystal composition having negative Δ∈ are necessary as the vertical alignment mode and the IPS for the effective display modes which improve the viewing angle, and they have been desired strongly. Formerly, compounds having 2,3-difluorophenylene group have been mainly used as the composition having negative Δ∈ (as refer to patent document 1). However, a problem exists that the absolute value of Δ∈ of the liquid crystal composition using the compound is not sufficiently large (as refer to patent document 2) .

Therefore, a trifluoronaphthalene derivative is reported as a compound having negative Δ∈ of a larger absolute value than the compound having 2,3-difluorophenylene group (as refer to patent document 3). However, the demand for further reducing the consumption of electric power in a liquid crystal display device is strong, and, in this issue, the absolute value of Δ∈ is not sufficiently large even in case of using a trifluoronaphthalene moiety.

On the other hand, a compound having a trifluoromethyl group at a lateral position of benzene ring (as refer to patent document 4) is reported. Furthermore, it is also reported that the compound described in the cited document can be advantageously used as an element of the liquid crystal composition having negative Δ∈ of a larger absolute value. However, the compound having a trifluoromethyl group at a lateral position of benzene ring has a problem that the absolute value of dielectric anisotropy does not attain sufficiently large because of the following reason. That is, in the compound having negative Δ∈, in order to make the absolute value of Δ∈ larger, it is necessary to replace substituent groups having large electron-withdrawing group at a lateral position of benzene. However, since a 1,4-phenylene group has only two lateral substituent positions as 2-substituted position and 3-substituted position, a limit to increase the absolute value of Δ∈ exists.

Moreover, in the structure such as a biphenyl moiety which is connected with two 1,4-phenylene groups, the electron-withdrawing group replaced on two adjacency phenylene groups hardly turns to the same direction, and the absolute value of Δ∈ does not generally increase. Thus, as mentioned above, development of the compound having an absolute value of larger Δ∈ in a negative Δ∈ compound has been desired.

Patent document 1: JP-T-H02-503441

Patent document 2: JP-A-H10-176167

Patent document 3: DE: 195 22 195 Description

Patent document 4: JP-A-H08-40953

Problems to be Solved

The problems to be solved in the present invention relates to provide a compound having larger absolute value of Δ∈ in a negative Δ∈ compound, and to provide a practical liquid crystal composition by using the compound thereof.

The present invention provides a 1-(trifluoromethyl)naphthalene derivative represented by the general formula (I) as a means for solving the above-mentioned problems, provides a liquid crystal composition containing one or more kinds of compounds represented by the general formula (I), and further provides a liquid crystal device in which a component is the liquid crystal composition.

(In the formula, each R 1 and R 2 represents independently an alkyl group having 1 to 12 carbon numbers, an alkenyl group having 2 to 12 carbon numbers, an alkoxyl group having 1 to 12 carbon numbers, or an alkenyloxy group having 2 to 12 carbon numbers;

each one or more hydrogen atoms may be independently replaced with a fluorine atom, and each —CH 2 — group may be independently replaced with —O—, —S—, —CO—, —COO—, —OCO—, or —OCOO—; each A 1 , A 2 , B 1 , and B 2 represents independently a trans-1,4-cyclohexylene group, a trans-1,3-dioxane-2,5-diyl group, a pyridine-2,5-diyl group, a pyrimidine 2,5-diyl group, or a 1,4-phenylene group which may be replaced with one or more fluorine atoms; each L 1 , L 2 , M 1 , and M 2 represents independently a single bond, —CH 2 CH 2 —, —CH═CH—, —CH≡CH—, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, —CF 2 CF 2 —, —CF═CF—, —OCO—, —COO—, —CH(CH 3 )CH 2 —, —CH 2 CH(CH 3 )—, —CH(CH 3 )CH(CH 3 )—, —OCH(CH 3 )—, —CH(CH 3 )O—, —(CH 2 ) 4 —, —(CH 2 ) 3 O—, —O(CH 2 ) 3 —, —COS—, or —SCO—; each X 1 and X 2 represents independently a hydrogen atom or a fluorine atom; and each p, q, r, and s represents independently 0 or 1.)

A liquid crystal compound of the present invention is characterized in that a trifluoromethyl group having very large electron-withdrawability is replaced at 1-substituted position of a naphthalene ring. Therefore, a liquid crystal compound having this moiety has large polarization in the direction of a minor axis of a molecule, and has a negative dielectric anisotropy with a large absolute value as a result.

A compound represented by the general formula (I) of the present invention has a Δ∈ of negative and extremely large absolute value. Furthermore, since it is chemically stable with heat, light, water and the like, and excels in compatibility with a liquid crystal compound or a liquid crystal composition widely used now, so it is suitable as an element of the practical liquid crystal composition in which low voltage drive is possible.

In the general formula (I), each R 1 and R 2 represents independently an alkyl group having 1 to 12 carbon numbers, an alkenyl group having 2 to 12 carbon numbers, an alkoxyl group having 1 to 12 carbon numbers, or an alkenyloxy group having 2 to 12 carbon numbers, each one or more hydrogen atoms may be replaced independently with a fluorine atom, and each —CH 2 — group may be replaced independently with —O—, —S—, —CO—, —COO—, —OCO—, or —OCOO—; it is preferable that each R 1 and R 2 is an alkyl group having 1 to 8 carbon numbers, an alkenyl group having 2 to 8 carbon numbers, an alkoxyl group having 1 to 7 carbon numbers, or an alkenyloxy group having 2 to 7 carbon numbers; and it is more preferable that each R 1 and R 2 is a linear alkyl group having 2 to 5 carbon atoms, a vinyl group, a 3-butenyl group, a trans-1-propene-1-yl group, or a trans-3-pentene-1-yl group.

Each A 1 , A 2 , B 1 , and B 2 represents independently a trans-1,4-cyclohexylene group, a trans-1,3-dioxane-2,5-diyl group, a pyridine-2,5-diyl group, a pyrimidine 2,5-diyl group, or a 1,4-phenylene group which may be replaced with one or more fluorine atoms; it is preferable that each A 1 , A 2 , B 1 , and B 2 is a trans-1,4-cyclohexylene group or a 1,4-phenylene group which may be replaced with one or more fluorine atoms; and it is more preferable that they is a trans-1,4-cyclohexylene group or a 1,4-phenylene group without substitution.

Each L 1 , L 2 , M 1 , and M 2 represents independently a single bond, —CH 2 CH 2 —, —CH═CH—, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, —CF 2 CF 2 —, —CF═CF—, —OCO—, —COO—, —CH(CH 3 )CH 2 —, —CH 2 CH(CH 3 )—, —CH(CH 3 )CH(CH 3 )—, —OCH(CH 3 )—, —CH(CH 3 )O—, —(CH 2 ) 4 —, —(CH 2 ) 3 O—, —O(CH 2 ) 3 —, —COS—, or —SCO—; it is preferable that each is independently a single bond, —CH 2 CH 2 —, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, or —CF 2 CF 2 —; and it is more preferable that each is a single bond or —CH 2 CH 2 —.

Each X 1 and X 2 represent independently a hydrogen atom or a fluorine atom, and, in order to make Δ∈ larger, it is preferable that each X 1 and X 2 is a fluorine atom. While p, q, r, and s represents 0 or 1, it is preferable that the sum of p, q, r and s is an integer of 1 or more and 3 or less, and it is more preferable that the sum of p, q, r and s is 1 or 2.

Although compounds of the general formula (I) may include various kinds of compounds as mentioned above by selection of R 1 , R 2 , A 1 , A 2 , B 1 , B 2 , L 1 , L 2 , M 1 , M 2 , X 1 , X 2 , p, q, r, and s; among these, each compound represented by the following general formula (I-a-a) to general formula (I-h-k) is preferable.

(In the formulas, each R 1 and R 2 represents an alkyl group having 1 to 8 carbon numbers, an alkenyl group having 2 to 8 carbon numbers, an alkoxyl group having 1 to 7 carbon numbers, or an alkenyloxy group having 2 to 7 carbon numbers.)

Furthermore, in the above formulas, each compound of a general formula (I-a-a) to a general formula (I-a-d), a general formula (I-b-c) to a general formula (I-b-e), a general formula (I-c-a) to a general formula (I-c-e), and a general formula (I-d-c) to a general formula (I-d-d) is particularly preferable. A compound of (I) of the present invention can be prepared, for example, as follows. A naphthalene derivative represented by the general formula (II)

(In the formula, R 1 , R 2 , A 1 , A 2 , B 1 , B 2 , L 1 , L 2 , M 1 , M 2 , X 1 , X 2 , p, g, r, and s represent the same meaning with the general formula (I).) is iodized with N-iodosuccinimide, iodine, and the like; and a 1-iodonaphthalene derivative (III) is obtained.

(In the formula, R 1 , R 2 , A 1 , A 2 , B 1 , B 2 , L 1 , L 2 , M 1 , M 2 , X 1 , X 2 , p, q, r, and s represent the same meaning with the general formula (I).) The compound represented by the general formula (I) can be obtained by acting trifluoromethyltrimethylsilane on the obtained compound (III) in the presence of a fluorinated compound such as sodium fluoride, potassium fluoride, cesium fluoride, and the like and a copper salt such as copper(I) chloride, copper(I) bromide, copper(I) iodide, and the like in a nonpolar protic solvent such as N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and the like.

Or a 1-iodo-2-naphthol derivative (V) is obtained by acting N-iodosuccinimide, iodine, and the like on a 2-naphthol derivative (IV).

(In the formula, R 1 , A 1 , B 1 , L 1 , M 1 , X 1 , X 2 , p and q represent the same meaning with the general formula (I).)

(In the formula, R 1 , A 1 , B 1 , L 1 , M 1 , X 1 , X 2 , p and q represent the same meaning with the general formula (I).) A 1-iodo naphthalene derivative (VI) is obtained by acting trifluoromethanesulfonic anhydride, p-toluensulfonyl chloride, methanesulfonyl chloride, and the like on the obtained 1-iodo-2-naphthol derivative (V) in the presence of a base such as pyridine and triethylamine, and the like.

(In the formula, R 1 , A 1 , B 1 , L 1 , M 1 , X 1 , X 2 , p and q represent the same meaning with the general formula (I), and Z 1 represents a leaving group such as a trifluoromethanesulfonyl group, a p-toluenesulfonyl group, a methanesulfonyl group, and the like.)

A compound represented by the general formula (III) can also be obtained by acting an organometallic compound (VII) on the compound (VI) in the presence of a transition metal catalyst of a palladium system, a nickel system, or an iron system such as tetrakis(triphenylphosphine)palladium(0), (1,2-bis(diphenylphosphino)ethane)dichloronickel(II), tris(acetylacetonato)iron(III), and the like.

(In the formula, R 2 , A 2 , B 2 , L 2 , M 2 , r and s represent the same meaning with the general formula (I), and Z 2 represents a metal or a metallic salt such as magnesium chloride, zinc chloride, lithium, copper, copper-lithium, trialkylsilane, boric acid, and the like.)

Or, a naphthalene derivative (VIII) is obtained by acting trifluoromethanesulfonic anhydride, p-toluensulfonyl chloride, methanesulfonyl chloride, and the like on the 2-naphthol derivative (IV) in the presence of a base such as pyridine, triethylamine, and the like.

(In the formula, R 1 , A 1 , B 1 , L 1 , M 1 , X 1 , X 2 , p and q represent the same meaning with the general formula (I), and Z 1 represents a leaving group such as a trifluoromethanesulfonyl group, a p-toluenesulfonyl group, a methanesulfonyl group, and the like.) A 1-iodo naphthalene derivative (VI) can also be obtained by acting N-iodosuccinimide, iodine, and the like on the obtained compound (VIII).

Or, a 1-(trifluoromethyl)-2-naphthol derivative (IX) is obtained by acting trifluoromethyltrimethylsilane on the 1-iodo-2-naphthol derivative (V), in the presence of a fluorinated compound such as sodium fluoride, potassium fluoride, cesium fluoride, and the like and a copper salt such as copper(I) chloride, a copper(I) bromide, a copper(I) iodide, and the like in a nonpolar protic solvent such as N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and the like.

(In the formula, R 1 , A 1 , B 1 , L 1 , M 1 , X 1 , X 2 , p and q represent the same meaning with the general formula (I).)

A 1-(trifluoromethyl)naphthalene derivative (X) is obtained by acting trifluoromethanesulfonic anhydride, p-toluensulfonyl chloride, methanesulfonyl chloride, and the like on the obtained 1-(trifluoromethyl)-2-naphthol derivative (IX), in the presence of a base such as pyridine, triethylamine, and the like.

(In the formula, R 1 , A 1 , B 1 , L 1 , M 1 , X 1 , X 2 , p and q represent the same meaning with the general formula (I), and Z 1 represents a leaving group such as a trifluoromethanesulfonyl group, a p-toluenesulfonyl group, a methanesulfonyl group, and the like.)

A compound represented by the general formula (I) can also be obtained by acting an organometallic compound (VII) on the obtained compound (X) in the presence of transition metal catalyst of palladium, nickel, or iron such as tetrakis(triphenylphosphine)palladium(0), (1,2-bis(diphenylphosphino)ethane)dichloronickel(II), tris(acetylacetonato)iron(III) and the like.

Many of the compounds represented by the general formula (I) show comparatively excellent compatibility to other liquid crystal materials. Moreover, they can also obtain easily high resistivity and high voltage holding ratio. Therefore, they can be used suitably as a material for liquid crystal display cell in the state of a mixture with other liquid crystal compounds. A compound represented by the general formula (I) can increase the absolute value of Δ∈ greatly by adding it, can reduce the threshold voltage, also has an advantage of possibility of both of a high-speed response and an increase in birefringence (Δn). Therefore, the compounds represented by the general formula (I) can be used in any of the various above-mentioned display types. Besides, it is suitable to be used for a TN type display device of a simple matrix drive or of an active-matrix drive, and for a STN display device; and it is preferable to be used particularly as a polar element for the liquid crystal material of a TN display device of an active-matrix drive.

Thus, as a preferable representative example of the nematic liquid crystal compound which can be used by mixing with the compound represented by the general formula (I), in the compositions provided by the present invention, it is preferable to contain at least one kind of the compound represented by the general formula (I) as the first element, and contains one or more kinds of compounds represented particularly by the following general formula (A) as other elements.

(In the formula, R c represents a linear alkyl group or an alkenyl group having 1 to 7 carbon atoms, R d represents a linear alkyl group, an alkenyl group, an alkoxyl group, or an alkenyloxy group having 1 to 12 carbon atoms, p3 represents 0 or 1, each M b and M c represent independently a single bond, —COO—, or —CH 2 CH 2 —, and G c represents a trans-1,4-cyclohexylene group or a -1,4-phenylene group.)

In the general formula (A), it is preferable that R c is a linear alkyl group having 2 to 7 carbon atoms, a 1-alkenyl group having 2 to 5 carbon atoms, or a 3-alkenyl group having 4 to 5 carbon atoms; as a linear alkyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group is more preferable; as a 1-alkenyl group, a vinyl group or a trans-1-propenyl group is more preferable; and as a 3-alkenyl group, a 3-butenyl group or a trans-3-pentenyl group is more preferable. It is preferable that R d is a linear alkyl group having 1 to 7 carbon atoms, a 1-alkenyl group having 2 to 5 carbon atoms, a 3-alkenyl group having 4 to 5 carbon atoms, and a linear alkoxyl group having 1 to 3 carbon atoms. In the case when M b exists, it is preferable that at least one part of M b and M c is a single bond.

As a compound represented by the general formula (A), a compound represented by the following general formula (A-1) to the following general formula (A-14) is preferable, and a compound represented by the general formula (A-1), the general formula (A-2), the general formula (A-3), the general formula (A-5), or the general formula (A-6) is particularly preferable.

(In the formula, each R A and R B represents independently a linear alkyl group having 1 to 7 carbon atoms, a 1-alkenyl group having 2 to 3 carbon atoms, or a 3-alkenyl group having 4 to 5 carbon atoms; R C represents a linear alkyl group having 1 to 5 carbon atoms, or a linear 2-alkenyl group having 3 to 4 carbon atoms; R D represents a linear alkyl group having 1 to 3 carbon atoms, or a 3-alkenyl group having 4 to 5 carbon atoms; and R E represents a linear alkyl group having 1 to 3 carbon atoms, or a linear 2-alkenyl group having 3 to 4 carbon atoms.)

In the liquid crystal composition of the present invention,

(In the formula, R e represents an alkyl group having 1 to 7 carbon atoms; R f represents a linear alkyl group, an alkoxyl group, or an alkenyloxy group having 1 to 7 carbon atoms; p4 represents 0 or 1; each M d and M e represent independently a single bond, —CH 2 CH 2 —, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, or —COO—; and G d represents a trans-1,4-cyclohexylene group or an -1,4-phenylene group which may be replaced with 1 or 2 fluorine atoms.) one or more kinds of 2,3-difluoro-1,4-phenylene derivatives represented by the general formula (B) may be contained.

In the general formula (B), it is preferable that R e is a linear alkyl group having 2 to 7 carbon atoms. It is preferable that R f is a linear alkyl group and a linear alkoxyl group having 1 to 5 carbon atoms; and a linear alkyl group having 1 to 4 carbon atoms, or a linear alkoxyl group having 1 to 4 carbon atoms is particularly preferable. It is preferable that one of M d and M e is a single bond, and that the other is a single bond, —CH 2 CH 2 — or —COO—.

Although a great many compounds are included in the general formula (B), compounds represented by the following general formula (B-1) to the general (B-9) are preferable.

In the above formulas, R F represents a linear alkyl group having 1 to 7 carbon atoms; and R G represents a linear alkyl group having 1 to 5 carbon atoms, or a linear alkoxyl group having 1 to 4 carbon atoms.

Moreover, in the liquid crystal composition of the present invention, it may contain one or more kinds of compounds represented by the general formula (C) to the general formula (G).

(In the formulas, R g , R i , R k , and R m represent a linear alkyl group having 1 to 7 carbon atoms; R h , R j , and R n represent a linear alkyl group, an alkoxyl group, or an alkenyloxy group having 1 to 7 carbon atoms; R l represents a linear alkyl group having 1 to 7 carbon atoms; R o represents a linear alkyl group, an alkoxyl group having 1 to 7 carbon atoms, or a linear alkenyl group, alkenyloxy group having 2 to 7 carbon atoms; R p represents a linear alkyl group having 1 to 7 carbon atoms, or a linear alkenyl group having 2 to 7 carbon atoms; X a and X b represent a hydrogen atom or a fluorine atom; each p5, p6, p7, and p8 represents independently 0 or 1; each p9 and p10 represents independently 0, 1 or 2; the sum of p9 and p10 is 1 or 2; each M f and M g , M h and M i , M j and M k , M l , M m , and M n represents independently a single bond, —CH 2 CH 2 —, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, or —COO—; M o represents a single bond or —CH 2 CH 2 —; each G e , G f , G g , G h , G i , and G j represents independently a trans-1,4-cyclohexylene group or -1,4-phenylene group which may be replaced with 1 or 2 fluorine atoms; and in the case when a choice of G i , G j , M n and M o are, they may be same, or may be different.)

In the general formula (C) to the general formula (G), it is preferable that R g , R i , R k , R m , and R p is a linear alkyl group having 2 to 7 carbon atoms. It is preferable that R h , R j , R n , and R o is a linear alkyl group, a linear alkoxyl group having 1 to 5 carbon atoms. It is preferable that R l is a linear alkyl group having 1 to 3 carbon atoms. Each M f and M g , M h and M i , M j and M k , M l and M m represents independently a single bond, —CH 2 CH 2 —, —OCH 2 —, —CH 2 O—, —OCF 2 —, —CF 2 O—, or —COO—; it is preferable that one is a single bond, and the other is a single bond, —CH 2 CH 2 —, or —COO—. It is preferable that M n is a single bond, —CH 2 CH 2 —, —CH 2 O—, or —CF 2 O—.

Embodiments

Hereinafter is a further description of the present invention with reference to embodiments. However, the present invention is not to be limited to these embodiments.

Further, the measurement of phase transition temperature was performed with a polarizing microscope equipped with a hot stage and together with a differential scanning calorimeter (DSC). Also, the structure of the compounds was confirmed by nuclear magnetic resonance spectrum (NMR), infrared resonance spectrum (IR), mass spectrum (MS), and the like.