Disclosure of Invention
The invention aims to provide a liquid crystal material with excellent performance.
An object of the present invention is to provide a liquid crystal compound having a negative dielectric anisotropy with a large absolute value.
Another object of the present invention is to provide a liquid crystal composition containing the above liquid crystal compound.
Another object of the present invention is to provide a liquid crystal display material or a liquid crystal display element produced by using the above liquid crystal composition.
Specifically, the invention provides the following technical scheme:
in a first aspect, the present invention provides a liquid crystal compound, said compound being according to formula I:
in the formula (I), the compound is shown in the specification,
ring a1 represents 2,3,5, 6-tetrafluoro-1, 4-phenylene;
the a2 ring represents 2, 3-difluoro-1, 4-phenylene;
xa, Xb, Xc and Xd are each independently selected from F, Cl and H;
R1is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
R2is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
when Y is a single bond, Z is a single bond, methyleneoxy (-CH)2O-) or-COO-; or Y is- (CH)2) n-; wherein, when n is 1 or 2; z is a single bond.
In a preferred embodiment, in formula I, when Y is- (CH)2) n-; wherein, when n is 1 or 2; when Z is a single bond, Xa, Xb, Xc and Xd are each independently selected from F, Cl and H; and at least two of Xa, Xb, Xc, and Xd are not H.
In a preferred embodiment, the compound is a compound of formula I-1, a compound of formula I-2, a compound of formula I-3, a compound of formula I-4, a compound of formula I-5, a compound of formula I-7, or a compound of formula I-8:
in the following formulas, the first and second groups,
each R is1Each independently is an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms;
ring F represents 2,3,5, 6-tetrafluoro-1, 4-phenylene.
The second aspect of the present invention provides a liquid crystal composition comprising a component (a), a component (b) and a component (c);
the component (a) is one or more compounds in the compounds of the formula I;
in the formula I, the compound is shown in the specification,
ring a1 represents 2,3,5, 6-tetrafluoro-1, 4-phenylene;
the a2 ring represents 2, 3-difluoro-1, 4-phenylene;
xa, Xb, Xc and Xd are each independently selected from F, Cl and H;
R1is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
R2is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
when Y is a single bond, Z is a single bond, methyleneoxy (-CH)2O-) or-COO-; or Y is- (CH)2) n-; wherein, when n is 1 or 2; z is a single bond;
the component (b) is one or more compounds in the compound shown in the formula II;
in the formula II, the reaction mixture is shown in the specification,
the a2 ring represents 2, 3-difluoro-1, 4-phenylene;
ring A3 represents 1, 4-phenylene or 1, 4-cyclohexylene;
ring a4 represents 1, 4-cyclohexylene;
z is a single bond, methyleneoxy (-CH)2O-) or-COO-;
R1is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
R2is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
the component (c) is a compound of formula III;
in a preferred embodiment, in formula I, when Y is- (CH)2) n-; wherein, when n is 1 or 2; when Z is a single bond, Xa, Xb, Xc and Xd are each independently selected from F, Cl and H; and XaAt least two of Xb, Xc and Xd are not H.
In a preferred embodiment, the component (a) is one or more compounds selected from the group consisting of: a compound of formula I-1, a compound of formula I-2, a compound of formula I-3, a compound of formula I-4, a compound of formula I-5, a compound of formula I-6, a compound of formula I-7, a compound of formula I-8, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is1Each independently is an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms;
ring F represents 2,3,5, 6-tetrafluoro-1, 4-phenylene.
In a preferred embodiment, the component (b) is one or more compounds selected from the group consisting of: a compound of formula II-1, a compound of formula II-2, a compound of formula II-3, a compound of formula II-4, a compound of formula II-5, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is1Each independently is an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms.
In a preferred embodiment, the liquid crystal composition further comprises a component (d); the component (d) is one or more compounds selected from the group consisting of: a compound of formula IV-1, a compound of formula IV-2, a compound of formula IV-3, a compound of formula IV-4, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is3Each independently is an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms;
each R is4Each independently is an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms.
In a preferred embodiment, the liquid crystal composition further comprises a component (e); the component (e) is one or more compounds selected from the group consisting of: a compound of formula V-1, a compound of formula V-2, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is5Each independently is an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkenyl group having 2 to 5 carbon atoms.
In a preferred embodiment, the liquid crystal composition further comprises a component (f); the component (f) is one or more compounds selected from the group consisting of: a compound of formula VI-1, a compound of formula VI-2, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is6Each independently is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms.
In a preferred embodiment, the liquid crystal composition further comprises a component (g); the ingredient (g) is one or more compounds selected from the group consisting of: a compound of formula VII-1, a compound of formula VII-2, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is7Each independently is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms.
In a preferred embodiment, the liquid crystal composition further comprises a component (h); the component (h) is one or more compounds selected from the group consisting of: a compound of formula VIII-1, a compound of formula VIII-2, a compound of formula VIII-3, or any combination of the foregoing;
in the following formulas, the first and second groups,
each R is8Each independently is an alkoxy group having 1 to 6 carbon atoms;
ring F represents 2,3,5, 6-tetrafluoro-1, 4-phenylene.
In another preferred embodiment, the liquid crystal composition comprises a component (a), a component (b) and a component (c); and one or more of the following components: component (d), component (e), component (f), component (g) and component (h).
As used herein, the ingredient (a) is one or more compounds of formula I.
As used herein, the ingredient (b) is one or more compounds of formula II.
As used herein, the component (c) is a compound of formula III.
As used herein, the component (d) is one or more compounds selected from the group consisting of compounds of formula IV-1, compounds of formula IV-2, compounds of formula IV-3, and compounds of formula IV-4.
As used herein, the ingredient (e) is one or more compounds of the formula V-1 and formula V-2.
As used herein, the component (f) is one or more compounds of the formula VI-1 and VI-2.
As used herein, the component (g) is one or more compounds of formula VII-1 and formula VII-2.
As used herein, the ingredient (h) is one or more compounds selected from the group consisting of a compound of formula VIII-1, a compound of formula VIII-2, and a compound of formula VIII-3.
In another preferred embodiment, the liquid crystal composition comprises a component (a), a component (b) and a component (c); and component (d) and component (e).
In another preferred embodiment, the liquid crystal composition comprises a component (a), a component (b) and a component (c); and a component (f).
In another preferred embodiment, the liquid crystal composition comprises a component (a), a component (b) and a component (c); and a component (e).
In another preferred embodiment, the liquid crystal composition comprises a component (a), a component (b) and a component (c); and a component (d).
In another preferred embodiment, the content of the component (a) in the liquid crystal composition is 15 to 40% by weight, based on 100% by weight. Preferably 15 to 30 percent.
In another preferred embodiment, the content of the component (b) in the liquid crystal composition is 20% to 50% by weight based on 100% by weight.
In another preferred embodiment, the content of the component (c) in the liquid crystal composition is 20 to 35% by weight based on 100% by weight.
In another preferred embodiment, the content of the component (d) in the liquid crystal composition is 0% to 30% by weight, based on 100% by weight.
In another preferred embodiment, the content of the component (e) in the liquid crystal composition is 0% to 20% by weight based on 100% by weight.
In another preferred embodiment, the content of the component (f) in the liquid crystal composition is 0% to 15% by weight based on 100% by weight.
The third aspect of the present invention provides a use of the liquid crystal compound according to the first aspect of the present invention or the liquid crystal composition according to the second aspect of the present invention for producing a liquid crystal display material or a liquid crystal display element.
The main advantages of the invention include:
the invention provides a liquid crystal compound with a novel structure, which can be used for preparing a liquid crystal composition with excellent performance so as to be used for manufacturing a liquid crystal display material or a liquid crystal display element.
The liquid crystal compound provided by the invention has a negative dielectric anisotropy value with a large absolute value, does not have a smectic phase or has a small temperature range of the smectic phase, and also has ultraviolet and thermal stability, a high clearing point and excellent co-solubility with the blended liquid crystal.
The liquid crystal composition provided by the invention comprises the liquid crystal compound. The liquid crystal composition has at least one of the following characteristics: rotational viscosity (gamma)1) The ratio is lower, the optical anisotropy value is proper, the absolute value of the negative dielectric anisotropy value is higher, the temperature of a nematic phase clearing point is higher, and the critical voltage is lower; or the liquid crystal composition has at least two of the above characteristics and the at least two characteristics have an appropriate balance.
A liquid crystal display material or a liquid crystal display element manufactured by using the liquid crystal compound or the liquid crystal composition of the present invention has at least one of the following characteristics: the response time is short, the driving voltage is low, the contrast is high, the visual angle is wide, the working temperature range is wide, and the like; or at least two of the above characteristics with a suitable balance.
It is to be understood that within the scope of the present invention, the above-described features of the present invention and those specifically described below (e.g., in the examples) may be combined with each other to form new or preferred embodiments. Not to be reiterated herein, but to the extent of space.
Detailed description of the invention
Term(s) for
As used herein, the term "alkyl group having 1 to 8 carbon atoms" refers to a straight or branched alkyl group having 1 to 8 carbon atoms. Alkyl groups having 1, 2,3, 4, 5,6, 7 or 8 carbon atoms are preferred. Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl and the like. The term "alkyl group having 1 to 6 carbon atoms" means a straight or branched alkyl group having 1 to 6 carbon atoms. An alkyl group having 1, 2,3, 4, 5 or 6 carbon atoms is preferred. The term "alkyl group having 1 to 5 carbon atoms" means a straight or branched alkyl group having 1 to 5 carbon atoms. An alkyl group having 1, 2,3, 4 or 5 carbon atoms is preferred.
As used herein, the term "alkoxy" is "alkyl-O-". The term "alkoxy group having 1 to 8 carbon atoms" means "alkyl-O-" having 1 to 8 carbon atoms ". The term "alkoxy group having 1 to 6 carbon atoms" means "alkyl-O-having 1 to 6 carbon atoms". The term "alkoxy group having 1 to 5 carbon atoms" means "alkyl-O-" having 1 to 5 carbon atoms ". Wherein the alkyl group having 1 to 8 carbon atoms, the alkyl group having 1 to 6 carbon atoms and the alkyl group having 1 to 5 carbon atoms are as defined above.
As used herein, the term "alkenyl group having 2 to 6 carbon atoms" refers to a straight or branched alkenyl group having 2 to 6 carbon atoms. "alkenyl having 2 to 5 carbon atoms" has a similar definition. Alkenyl groups having 2,3, 4, 5 or 6 carbon atoms are preferred.
The term "1, 4-cyclohexylene" as used herein, means that the point of attachment of the group to the rest of the molecule is at the 1,4 position of the cyclohexyl group.
The term "1, 4-cyclohexenylene" as used herein means that the point of attachment of the group to the rest of the molecule is at the 1,4 position of the cyclohexenyl group and may have 1 or 2 alkenyl groups on the ring.
The term "1, 4-phenylene" as used herein means that the point of attachment of the group to the rest of the molecule is at the 1,4 position of the phenyl group.
As used herein, the term "2, 3,5, 6-tetrafluoro-1, 4-phenylene" means that the point of attachment of the group to the rest of the molecule is at the 1,4 position of the phenyl group and that the 2,3,5,6 positions of the phenyl group are all substituted with fluorine.
As used herein, the term "2, 3-difluoro-1, 4-phenylene" means that the point of attachment of the group to the rest of the molecule is at the 1,4 position of the phenyl group and that both 2,3 positions of the phenyl group are substituted with fluorine.
As used herein, ring A1, i.e. ring A1
Represents 2,3,5, 6-tetrafluoro-1, 4-phenylene.
As used herein, ring A2, i.e. ring A2
Represents 2, 3-difluoro-1, 4-phenylene.
As used herein, the F ring, i.e.
Represents 2,3,5, 6-tetrafluoro-1, 4-phenylene.
As used herein, ring A3, i.e. ring A3
Represents a1, 4-phenylene group or a1, 4-cyclohexylene group.
As used herein, ring A4, i.e. ring A4
Represents a1, 4-cyclohexylene group.
Liquid crystal composition
The liquid crystal composition of the present invention comprises a plurality of liquid crystal compounds.
The liquid crystal composition at least comprises one or more compounds in the compounds shown in the formula I. The compound of formula I of the invention is a compound with novel structure. The compound may also be referred to herein as a compound of formula I or compound I. The concrete structure is as follows:
in the formula (I), the compound is shown in the specification,
ring a1 represents 2,3,5, 6-tetrafluoro-1, 4-phenylene;
the a2 ring represents 2, 3-difluoro-1, 4-phenylene;
xa, Xb, Xc and Xd are each independently selected from F, Cl and H;
R1is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
R2is alkyl with 1-6 carbon atoms or alkoxy with 1-6 carbon atoms;
when Y is a single bond, Z is a single bond, methyleneoxy (-CH)2O-) or-COO-; or Y is- (CH)2) n-; wherein, when n is 1 or 2; z is a single bond.
The compound has negative dielectric anisotropy and a small optical anisotropy value.
Liquid crystal compounds having a large absolute value of negative dielectric anisotropy, such as terphenyl compounds represented by formula B, are currently known:
the nematic phase is narrow, and the smectic phase is wide; and since terphenyl has a large conjugated system, the optical anisotropy value is extremely large, and thus terphenyl is not suitable as a component of a liquid crystal composition of IPS and VA.
Although the liquid crystal compound after modification, such as the compound represented by formula A,
it has a negative dielectric anisotropy value with a moderate absolute value and a moderate small optical anisotropy value, but it is considered that the dielectric anisotropy value is not large enough to have an unsatisfactory effect of reducing the driving voltage of the liquid crystal composition.
In the present invention, the inventors have utilized 2,3,5, 6-tetrafluorophenylene in place of cyclohexylene to produce compounds of formula I (especially compounds of formula I-1), with many improvements over compounds of formula A. Because the tetrafluorophenylene is symmetrical, is nonpolar and has small intermolecular, the compound does not generate a smectic phase, only has a nematic phase and has low viscosity. The optical anisotropy value is reduced compared to the terphenyl compound due to the reduction of the electron density in the tetrafluorophenylene group. In addition, the ultraviolet radiation resistance and heat resistance of the tetrafluorophenylene compound are higher than those of the cyclohexylene compound. Therefore, the liquid crystal compound with the tetrafluorophenylene structure, namely the compound shown in the formula I, has higher polarity, lower viscosity and lower birefringence than the compound shown in the formula A and the compound shown in the formula B; and has strong heat resistance and ultraviolet resistance.
The liquid crystal composition of the invention also comprises at least one or more compounds in the compound of formula II of the invention. The compound has less optical anisotropy, and thus can be used for improving the optical anisotropy of a liquid crystal composition.
The liquid crystal composition of the present invention further comprises at least a compound of formula III of the present invention. The compound has very low rotational viscosity, so that the preparation of the liquid crystal composition with low rotational viscosity is facilitated.
The liquid crystal composition of the present invention may further comprise one or more compounds of formula IV of the present invention. The non-polarity of the compound is favorable for reducing the rotational viscosity of the liquid crystal composition, but is not favorable for improving the dielectric anisotropy and clearing points. The compound of formula IV in the invention comprises a compound of formula IV-1, a compound of formula IV-2, a compound of formula IV-3 and a compound of formula IV-4.
The liquid crystal composition of the present invention may further comprise one or more compounds of the formula V compounds of the present invention. The compound of the formula V comprises a compound of a formula V-1 and a compound of a formula V-2.
The liquid crystal composition of the present invention may further comprise one or more compounds of formula VI of the present invention. The compound of formula VI in the invention comprises a compound of formula VI-1 and a compound of formula VI-2.
The liquid crystal composition of the present invention may further comprise one or more compounds of formula VII of the present invention. The compound of formula VII in the invention comprises a compound of formula VII-1 and a compound of formula VII-2.
The liquid crystal composition of the present invention may further comprise one or more compounds of the formula VIII compounds of the present invention. The compound of formula VIII in the invention comprises a compound of formula VIII-1, a compound of formula VIII-2 and a compound of formula VIII-3.
The compounds of the formulae I to VIII can be used as components for producing negative dielectric anisotropic liquid crystals in the present invention. Among them, the compound of formula VI can be used to adjust driving voltage, viscosity, or optical anisotropy. The compounds of formula VII can be used to extend the nematic temperature range, e.g. to increase clearing point, to adjust optical anisotropy. The compounds of formula VIII can be used to adjust the optical anisotropy. When the content of the compound of formula V to the compound of formula VII is increased, the viscosity is decreased and the driving voltage Vth of the liquid crystal composition is increased. Therefore, the content of these compounds in the liquid crystal composition is suitable so that Vth can satisfy the requirement. If the absolute value of the dielectric anisotropy value of one of the compounds of formula V to VII contained in the liquid crystal composition is less than 4, if the content of these compounds is more than 40% by weight, a satisfactory low driving voltage may not be obtained. The content of compounds of formulae V to VII in the liquid crystal composition should not exceed 40%, preferably 15-30%.
Preferably, the liquid crystal composition provided by the invention has one or more of the following characteristics:
1) optical anisotropy: the birefringence Deltan (589nm, 25 ℃) is 0.09-0.12;
2) dielectric anisotropy: delta epsilon (1KHz, 25 ℃) is-2.0 to-4.5;
3) clearing the bright spots: tni (DEG C) is 78-82;
4) viscosity: v (mm)2The temperature/s at 25 ℃ is 15 to 24.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. Unless otherwise indicated, percentages and parts are percentages and parts by weight. The test materials and reagents used in the following examples are commercially available without specific reference.
Herein, the optical anisotropy Δ n of the liquid crystal composition was measured by the abbe refractometer method; the clearing point Tni was tested by the DSC method; the dielectric anisotropy Δ ∈ was tested by the wheatstone bridge method; the viscosity v was measured using a Ubbelohde viscometer.
In order to briefly illustrate the various embodiments, the liquid crystal compounds of the present invention are represented by code combinations. The codes and their corresponding groups are shown in table 1.
Table 1 groups and corresponding codes
For example,
can be represented by the corresponding code of the groups in the compound as 3OB (2F,3F,5F,6F) B (3F) B (2F,3F) O2.
Preparation example 1 preparation of liquid Crystal Compound (4-ethoxy-2, 3-difluorophenyl-1-yl) -2,3, 3', 5, 6-pentafluoro-4-propoxybiphenyl (noted as 3OB (2F,3F,5F,6F) B (3F) B (2F,3F) O2)
The first step is as follows: to a mixture of magnesium (1.0mol) and 100ml of THF was slowly added dropwise a THF solution of 4-propoxy-2, 3,5, 6-tetrafluorobromobenzene at 5 ℃ with the temperature being maintained. Stirring was then carried out for 2 hours until the magnesium turnings were consumed, resulting in a gray grignard solution. While maintaining the temperature at 0 deg.C, a solution of 3-fluoroiodobenzene (1.0mol) in 500ml of THF was gradually added, and the reaction was stirred at 23 deg.C for 3 hours. 300ml NH was added to the reaction solution4The solution was saturated with Cl and stirred well. Extracting with 200ml ethyl acetate for 2 times to obtain organic solution layer, and extracting with anhydrous MgSO4And (5) drying. Filtering to remove solid to obtain solution, and distilling under reduced pressure to obtain red residue. The product structure is as follows:
the second step is that: the above reaction product (0.3mol) was added to THF400ml to give a colorless homogeneous solution, which was cooled to-68 ℃. To this solution was added commercial Sec-butyllithium (corresponding to an amount of 0.33 mol) over a period of 3 hours, and the mixture was kept at a constant temperature. After stirring for a further 1 hour, a solution of iodine (0.31mol) in 250ml of THF is added, the temperature not exceeding-60 ℃. The reaction started to be colorless and became red. The reaction solution was gradually warmed to room temperature, and further stirred for 1 day and 1 night. Toluene was added to the reaction mixture, which was washed with 500ml of water and 400ml of saturated NaCl solution. Then using anhydrous Na2SO4And (5) drying. The solid was filtered off to give a solution, which was concentrated under reduced pressure to give a highly viscous oil. After standing, the mixture became a crystal. The crystals were washed with 100ml ethanol and recrystallized from 50ml heptane. The product structure is as follows:
the third step: to 2, 3-difluoroethoxybenzene (0.4mol) was added 200ml of THF and cooled to-70 ℃. While the reaction system was kept at below-65 deg.C, a cyclohexane solvent (1.06M solution) (0.44mol) of sec-butyllithium was added, and after stirring for 20 minutes, a solution of triisopropylboronic acid (0.6mol) in 50ml of THF was added at a temperature of-68 deg.C to-70 deg.C and further stirred for 3 hours. The reaction product was gradually warmed to room temperature (. about.18 ℃ C.), 100ml of 6M hydrochloric acid was added in its entirety, followed by stirring for 30 minutes and extraction with 300ml of diethyl ether 3 times. The collected extracts were washed with 100ml of saturated NaCl solution. The ether layer was washed with NaSO4And (5) drying. After removing the solid, concentration under reduced pressure gave a brown solid, which was washed thoroughly with 100ml of heptane to give light brown powdery crystalline 2, 3-difluoro-4-ethoxyphenylboronic acid (0.29 mol). The product structure is as follows:
the fourth step: 4- (3-fluoro-4-iodophenyl) 4-propoxy-2, 3,5, 6-tetrafluorobenzene (0.05mol), 2, 3-difluoro-4-ethoxyphenylboronic acid (0.05mol) and K2CO3(0.02mol)、Pd(PPh3)4(0.0015mol), 50ml of toluene and 50ml of ethanol, refluxing for 8 hours, cooling to room temperature, filtering off the catalyst, and concentrating the filtrate under reduced pressure. The obtained residue was subjected to silica gel column chromatography (eluent: mixed solution of heptane/toluene 10: 1) to obtain a crude product, which was recrystallized from 100ml of ethanol to obtain white solid (4-ethoxy-2, 3-difluorophenyl-1-yl) -2,3, 3', 5, 6-pentafluoro-4-propoxybiphenyl (described as 3OB (2F,3F,5F,6F) B (3F) B (2F,3F) O2) (0.031mol), and the yield was 62%. The product structure is as follows:
preparation example 2: preparation of the liquid crystalline Compound 4-ethoxy-2, 3-difluorophenyl-2, 3, 3', 5, 6-pentafluoro-4-propoxybenzoate (noted as 3OB (2F,3F,5F,6F) B (3F) EB (2F,3F) O2)
1) Synthesis of 4-propoxy-2, 3,5, 6-tetrafluorophenylboronic acid
Under the protection of nitrogen, 4-propoxy-2, 3,5, 6-tetrafluorobromobenzene (0.025mol) and 10mL of dry THF are added into a 100mL three-neck flask, the temperature is reduced to-20 ℃, 35mL (0.029mol) of i-PrMgCl/THF is dripped in, the dripping is finished after 10min, and the reaction is carried out for 2 hours under the condition of heat preservation. 5.3g (0.028mol) of triisopropyl borate are added dropwise, the reaction is continued for 2 hours at low temperature after 5 min. 3.65g of 30% hydrochloric acid are added dropwise, the reaction is carried out at-10 ℃ for 1h, and the temperature is automatically raised to room temperature. THF was evaporated under reduced pressure and the crude product was dissolved in a mixture of ethyl acetate and water. After standing for separation, the aqueous phase was extracted twice with ethyl acetate, and the organic phases were combined and dried over anhydrous magnesium sulfate. And (3) evaporating the solvent under reduced pressure to obtain a solid, pulping the solid by using n-hexane, cooling, standing, and filtering to obtain a white solid product, namely 4-propoxy-2, 3,5, 6-tetrafluorophenylboronic acid, wherein the yield is 60%.
2) Synthesis of 2, 3-difluoro-4-ethoxyphenol
18.4g (0.091mol) of 2, 3-difluoro-4-ethoxyphenylboronic acid, 10.9g (0.182mol) of glacial acetic acid and 70mL of dry tetrahydrofuran are added into a 250mL three-neck flask, 40.8g (11.2mol) of hydrogen peroxide is dropwise added from a normal-pressure dropping funnel in an ice-water bath, the temperature of a reaction solution is controlled below 40 ℃ in the dropwise adding process, 10min of dropwise addition is finished, the reaction is continued for 20h at normal temperature, and the TLC tracking reaction is completed. To the reaction solution, 100mL of an aqueous solution of sodium sulfate (15%) was added and stirred for 5min, and extracted with methyl tert-butyl ether to obtain an organic phase, which was dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure to obtain 15.80g of a white solid product, yield: 99.7 percent. Melting point: 72.7-73.4 ℃.
3) Synthesis of 2, 3-difluoro-4-ethoxy phenyl p-iodobenzoate
2.5g (10.1mmol) of p-iodobenzoic acid, 2.1g (10.0mmol) of 2, 3-difluoro-4-ethoxyphenol, 2.3g (11.1mmol) of dicyclohexylcarbodiimide and 90mg (0.74mmol) of 4-dimethylaminopyridine were added to a 100mL three-necked flask under nitrogen protection, dissolved by adding 60mL of tetrahydrofuran, magnetically stirred, reacted at room temperature for 30 hours, and the reaction was followed by TLC to completion. And (2) carrying out suction filtration on reaction liquid, washing a solid by using dichloromethane, respectively washing the obtained lower-layer mother liquor by using 5% acetic acid, saline water and water for three times, drying an obtained organic phase by using anhydrous sodium sulfate, and distilling under reduced pressure to remove a solvent to obtain a solid, wherein the solid is prepared by using petroleum ether: the eluent of dichloromethane ═ 1:1 was passed through the column and the crude product obtained was purified again using petroleum ether: recrystallization from a solvent mixture of 20:1 dichloromethane gave 2.70g of the product as a white solid in yield: 67%.
4) Synthesis of 4-ethoxy-2, 3-difluorophenyl-2, 3, 3', 5, 6-pentafluoro-4-propoxybenzoate (noted as 3OB (2F,3F,5F,6F) B (3F) EB (2F,3F) O2)
280mg (1.1mmol) of 4-n-propoxy-2, 3,5, 6-tetrafluorophenylboronic acid were mixed with 400mg (1.0mmol) of (2, 3-difluoro-4-ethoxyphenyl) -2-fluoro 4-iodobenzoate (1.0mmol), Pd (PPh)3)4(0.011mmol)、K2CO3(1.5mmol) and 20mL ethanol were added to a 100mL three-necked flask under nitrogen and stirred magnetically. The reaction was carried out under reflux for 5h followed by TLC, complete reaction, cooling, suction filtration and washing of the solid with methyl tert-butyl ether. Washing the lower mother liquor with water (50mL × 5), collecting yellow organic phase, drying with anhydrous sodium sulfate, evaporating the solvent under reduced pressure, eluting with petroleum ether: column chromatography of ethyl acetate 40:1 afforded the crude product as a white solid which was recrystallized from petroleum ether to afford 0.48g of the product as a white solid in yield: 89 percent.
The other compounds of the formula I used in the individual examples were prepared according to the process of preparation 1 or 2, using the corresponding starting materials. The code combinations and mass spectral data for the compounds of formula I prepared are as follows:
| compound (I)
|
MS(m/z,%)
|
| 3OB(2F,3F,5F,6F)BB(2F,3F)O2
|
440.12
|
| 5OB(2F,3F,5F,6F)BB(2F,3F)O2
|
468.15
|
| 3OB(2F,3F,5F,6F)B(3F)B(2F,3F)O2
|
458.11
|
| 3OB(2F,3F,5F,6F)B(2F)B(2F,3F)O2
|
458.11
|
| 5OB(2F,3F,5F,6F)B(2F)B(2F,3F)O2
|
486.14
|
| 4OB(2F,3F,5F,6F)BB(2F,3F)O2
|
454.14
|
| 5OB(2F,3F,5F,6F)B(3F)B(2F,3F)O2
|
486.14
|
| 3OB(2F,3F,5F,6F)BEB(2F,3F)O2
|
484.11
|
| 3OB(2F,3F,5F,6F)B(2F)EB(2F,3F)O2
|
502.1
|
| 3OB(2F,3F,5F,6F)B(3F)EB(2F,3F)O2
|
502.1 |
Example 1 liquid Crystal composition 1
1 st component
3OB(2F,3F,5F,6F)BB(2F,3F)O2 10%
5OB(2F,3F,5F,6F)BB(2F,3F)O2 10%
3OB(2F,3F,5F,6F)B(3F)B(2F,3F)O2 10%
Component 2
Component 3
3HBO2 5%
3HB(2F,3F)O2 5%
Example 2 liquid Crystal composition 2
1 st component
3OB(2F,3F,5F,6F)B(2F)B(2F,3F)O2 10%
5OB(2F,3F,5F,6F)B(2F)B(2F,3F)O2 10%
3OB(2F,3F,5F,6F)B(3F)B(2F,3F)O2 10%
Component 2
Example 3 liquid Crystal composition 3
1 st component
Component 2
Component 3
3HB(2F,3F)O2 5%
4HB(2F,3F)O2 5%
Example 4 liquid Crystal composition 4
1 st component
Component 2
Example 5 liquid Crystal composition 5
1 st component
3OB(2F,3F,5F,6F)BB(2F,3F)O2 5%
3OB(2F,3F,5F,6F)BEB(2F,3F)O2 5%
3OB(2F,3F,5F,6F)B(2F)EB(2F,3F)O2 5%
Component 2
Example 6 liquid Crystal composition 6
1 st component
Component 2
Component 3
3HB(2F,3F)O2 10%
5HB(2F,3F)O2 10%
Example 7 liquid Crystal composition 7
1 st component
Component 2
Component 3
3HB(2F,3F)O2 6%
3BB(2F,3F)O2 6%
The results of the respective parameters of the liquid crystal compositions 1 to 7 are shown in table 2.
TABLE 2
As can be seen from table 2, the liquid crystal composition prepared according to the present invention has the following characteristics:
optical anisotropy: the birefringence Deltan (589nm, 25 ℃) is 0.09-0.12;
dielectric anisotropy: delta epsilon (1KHz, 25 ℃) is-2.0 to-4.5;
clearing the bright spots: tni (DEG C) is 78-82.
Viscosity: v (mm)2The temperature/s at 25 ℃ is 15 to 24.
Therefore, the liquid crystal composition has a good balance among the four characteristics of clearing point, optical anisotropy, dielectric anisotropy and viscosity.
Comparative example 1: comparative liquid Crystal composition 1
The 1 st component in the liquid crystal composition 7 of experimental example 7 was removed, and the additional component in the 3 rd component: 3BBB (2F,3F) O2 and 3BB (2F,3F) BO 2.
0 percent of the 1 st component
Component 2
Component 3
The physical properties of comparative liquid crystal composition 1 were as follows:
optical anisotropy: a birefringence Δ n (589nm, 25 ℃ C.) of 0.13;
dielectric anisotropy: delta epsilon (1KHz, 25 ℃) is-4.2;
clearing the bright spots: tni (. degree. C.) is 78;
viscosity: v (mm)2A temperature/s, 25 ℃) of 23.
In the comparative example, when 3BBB (2F,3F) O2 and 3BB (2F,3F) BO2 were used in place of the 1 st component in Experimental example 7, the viscosity of the liquid crystal composition was significantly increased although the absolute value of the dielectric anisotropy was increased, and the optical anisotropy was also increased, which was not favorable for improving the overall properties of the liquid crystal composition. It can be seen that the addition of the component belonging to the compound of formula I of the present invention to the liquid crystal composition is advantageous for improving the overall characteristics of the liquid crystal composition.
Comparative example 2 comparative liquid Crystal composition 2
Comparative liquid crystal composition 2 was prepared by replacing 3OB (2F,3F,5F,6F) B (3F) B (2F,3F) O2 in the 1 st component of liquid crystal composition 7 of Experimental example 7 with comparative compound 3OB (2F,3F,5F,6F)2B (3F) EB (2F,3F) O2.
The solubilities of the above two compounds in the liquid crystal compositions were compared in liquid crystal composition 7 and comparative liquid crystal composition 2, respectively: both sets of liquid crystal compositions were placed in a-20 ℃ freezer and deposition of crystals was observed.
The viscosities of liquid crystal composition 7 and comparative liquid crystal composition 2 were compared.
(3OB (2F,3F,5F,6F)2B (3F) EB (2F,3F) O2, comparative Compound)
(3OB (2F,3F,5F,6F) B (3F) B (2F,3F) O2, Compound prepared in preparation 1)
As a result, it was found that:
the solubility of the compound prepared in preparation example 1 of the present invention in liquid crystal composition 7 was significantly better than that of the comparative compound in comparative liquid crystal composition 2, at least 3 times higher.
Furthermore, the viscosity of the compound prepared in preparation example 1 of the present invention was significantly lower than that of the comparative compound, by about twenty percent.
All documents referred to herein are incorporated by reference into this application as if each were individually incorporated by reference. Furthermore, it should be understood that various changes and modifications of the present invention can be made by those skilled in the art after reading the above teachings of the present invention, and these equivalents also fall within the scope of the present invention as defined by the appended claims.