Compounds having a C—C triple bond and use thereof in liquid-crystal mixtures

Abstract

Compounds containing at least one CC triple bond of the formula I
R.sup.1-[A.sup.1-Z.sup.1].sub.m-A.sup.2A.sup.3-[Z.sup.2-A.sup.4].sub.n-[Z.sup.3-A.sup.5].sub.o-R.sup.2I,
which have neutral dielectric anisotropy, to the use thereof for high-frequency components, to liquid-crystalline media comprising the compounds, and to high-frequency components, in particular antennae, especially for the giga- and terahertz region, comprising these media. The liquid-crystalline media serve, for example, for the phase shifting of microwaves for tuneable phased-array antennae.

Claims

1. A compound of the formula I
R.sup.1-[A.sup.1-Z.sup.1].sub.m-A.sup.2A.sup.3-[Z.sup.2-A.sup.4].sub.n-[Z.sup.3-A.sup.5].sub.o-R.sup.2I in which one of A.sup.2 and A.sup.3 denotes ##STR00047## the other of A.sup.2 and A.sup.3, A.sup.1, A.sup.4 and A.sup.5, independently of one another, denote a) 1,4-phenylene, in which one or more CH groups may be replaced by N, or b) a radical of the formula ##STR00048## and in which, in the groups a) and b), one or more H atoms are optionally replaced, independently, by in each case a group Y, Y denotes Br, Cl, F, CN, NCS, SCN, SF.sub.5, C.sub.2-C.sub.10 alkenyl, C.sub.1-C.sub.10 alkoxy, C.sub.3-C.sub.6 cycloalkyl, C.sub.3-C.sub.6 cycloalkenyl or a mono- or polyfluorinated C.sub.1-C.sub.10 alkyl or alkoxy group, R.sup.1 and R.sup.2, independently of one another, denote a straight-chain alkyl radical having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CHCH, (CO)O, O(CO), (CO), or O in such a way that O atoms are not linked directly to one another, R.sup.3 denotes C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.10 alkenyl, C.sub.1-C.sub.10 alkoxy, C.sub.3-C.sub.6 cycloalkyl, C.sub.3-C.sub.6 cycloalkenyl or a mono- or polyfluorinated C.sub.1-C.sub.10 alkyl or alkoxy group, Z.sup.1, Z.sup.2 and Z.sup.3, independently of one another, denote a single bond, and m is 0, n and o are 1, where (m+n+o) is 2.

2. A compound according of claim 1, wherein the sub-formula -A.sup.2--A.sup.3- of the formula I is selected from the group consisting of: ##STR00049## ##STR00050## in which the parameters Y and R.sup.3 have the meanings given in claim 1.

3. A compound of claim 1, wherein the rings A.sup.1 to A.sup.5, if present, each denote an optionally substituted 1,4-phenylene ring.

4. A liquid-crystal medium, wherein said liquid-crystal medium comprises one or more compounds of the formula I according to claim 1.

5. A liquid-crystal medium of claim 4, wherein said liquid-crystal medium additionally comprises one or more compounds selected from the compounds of the formula II: ##STR00051## in which: L.sup.11 denotes R.sup.11 or X.sup.11, L.sup.12 denotes R.sup.12 or X.sup.12, R.sup.11 and R.sup.12, independently of one another, denote unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkynyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, X.sup.11 and X.sup.12, independently of one another, denote F, Cl, Br, CN, NCS, SCN, SF.sub.5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, fluorinated alkenyloxy or fluorinated alkoxyalkyl having 2 to 7 C atoms, p, q independently denote 0 or 1, Z.sup.11 to Z.sup.13, independently of one another, denote trans-CHCH, trans-CFCF, CC or a single bond, and ##STR00052## independently of one another, denote ##STR00053## in which L independently denotes branched or unbranched alkyl, alkenyl or alkynyl having 1 to 12 C atoms, in which, in addition, one or more CH.sub.2 groups may be replaced, independently of one another, by O, or denotes C.sub.3-C.sub.6 cycloalkyl, C.sub.3-C.sub.6 cycloalkenyl, fluorinated alkyl or alkenyl, fluorinated alkoxy or alkenyloxy, F, Cl, Br, CN, NCS, SCN or SF.sub.5.

6. A liquid-crystal medium of claim 4, wherein the concentration of the compounds of the formula I in the medium is in the range from in total 5% to 95%.

7. A method comprising including a compound of formula I in a component for high-frequency technology.

8. A method comprising including a compound of formula I in a liquid-crystalline medium.

9. A process for the preparation of a liquid-crystal medium according to claim 4, wherein one or more compounds of the formula I are mixed with one or more further compounds and optionally with one or more additives.

10. A component for high-frequency technology, wherein said component for high-frequency technology contains a liquid-crystal medium according to claim 4.

11. A component for high-frequency technology of claim 10, wherein said component for high-frequency technology comprises one or more functionally connected phase shifters.

12. A method of comprising including a liquid-crystal medium according to claim 4 in a component for high-frequency technology.

13. A phased array antenna, wherein said phased array antenna comprises one or more components according to claim 10.

14. A process for the preparation of 2-alkyl-1-bromo-3-fluorobenzenes, wherein 1-bromo-3-fluorobenzene is ortho-metallated using LDA and then alkylated in situ using the corresponding alkyl iodide.

15. The compound of claim 1 wherein formula I is defined as one of the following structures ##STR00054## wherein R.sup.1 and R.sup.2 denotes, identically or differently, an alkyl radical having 2 to 7 C atoms, R.sup.3 denotes an alkyl radical having 1 to 7 C atoms, an alkenyl radical having 2 to 7 C atoms, a cycloalkyl radical having 3 to 6 C atoms or a cycloalkenyl radical having 4 to 6 C atoms.

Description

EXAMPLES

(1) The acetylenes and boronic acids employed are commercially available or can be prepared analogously to known syntheses which are known to the person skilled in the art. The radicals C.sub.4H.sub.9 stand for unbranched n-butyl radicals. The corresponding situation applies to C.sub.3H.sub.7, C.sub.5H.sub.11, C.sub.6H.sub.13, etc.

Synthesis Example 1

Synthesis of 4-butyl-4-(4-butylphenylethynyl)-2-fluoro-3-propyl-[1,1;4,1]terphenyl (1)

(2) ##STR00040##

(3) The synthesis of 4-butyl-4-(4-butylphenylethynyl)-2-fluoro-3-propyl-[1,1;4,1]terphenyl (1) is carried out starting from 1-bromo-3-fluorobenzene (2) (CAS 1073-06-9).

1.1 Synthesis of 1-bromo-3-fluoro-2-propylbenzene (3)

(4) ##STR00041##

(5) n-Butyllithium (206.5 ml, 1.6 M in hexane, 0.33 mol) is added dropwise at 70 C. to a solution of diisopropylamine (46.4 ml, 0.33 mol) and 1,3-dimethyltetrahydro-2(1H)-pyrimidinone (42.3 g, 0.33 mol) in THF (750 ml), and the mixture is stirred at 0 C. for 30 min. The reaction mixture is cooled to 75 C., and a solution of 1-bromo-3-fluorobenzene (2) (54.6 g, 0.31 mol) in THF (250 ml) is slowly added dropwise at this temperature, and the mixture is stirred for a further 1 h. 1-Iodopropane (30.0 ml, 0.31 mol) is subsequently added dropwise at 70 C., and the reaction mixture is allowed to warm to room temperature over the course of 16 h with stirring. For work-up, the mixture is hydrolysed using dist. water, acidified by addition of hydrochloric acid, sodium hydrogensulfite is added, and the mixture is extracted with pentane (2). The combined organic phases are washed with dist. water (2), dried over sodium sulfate and evaporated in vacuo. The crude product is purified by filtration through silica gel (100% pentane), giving 1-bromo-3-fluoro-2-propylbenzene (3) in the form of a colourless oil.

1.2 Synthesis of 1-(4-butylphenylethynyl)-3-fluoro-2-propylbenzene (5)

(6) ##STR00042##

(7) Lithium bis(trimethylsilyl)amide (147 ml, 1.0 M in hexane, 0.15 mol) is added dropwise at 75 C. to a solution of 4-butylphenylacetylene (4) (CAS 79887-09-5) (24.5 g, 0.15 mol) in THF (800 ml). After 1 h, 9-methoxy-9-borabicyclo[3.3.1]nonane (147 ml, 1.0 M in hexane, 0.15 mol) is added dropwise, and the reaction mixture is stirred at this temperature for 1 h. Tris(dibenzylideneacetone)dipalladium (2.9 g, 3.2 mmol), 2-dicyclohexylphosphino-2,6-dimethoxybiphenyl (1.0 g, 2.5 mmol) and 1-bromo-3-fluoro-2-propylbenzene (28.5 g, 0.13 mol) are subsequently added at 20 C., and the mixture is heated under reflux for 16 h. The work-up is carried out by addition of methyl tert-butyl ether and dist. water. After the organic phase has been separated off, the aqueous phase is re-extracted with methyl tert-butyl ether. The combined organic phases are washed with ammonium chloride solution and sodium chloride solution, dried over sodium sulfate and evaporated in vacuo. The residue is purified by filtration through silica gel (100% heptane), giving 1-(4-butylphenylethynyl)-3-fluoro-2-propylbenzene (5) in the form of a yellow oil.

1.3 Synthesis of 1-(4-butylphenylethynyl)-3-fluoro-4-iodo-2-propylbenzene (6)

(8) ##STR00043##

(9) n-Butyllithium (97.0 ml, 1.6 M in hexane, 0.15 mol) is added dropwise at 90 C. to a mixture of 1-(4-butylphenylethynyl)-3-fluoro-2-propylbenzene (5) (43.5 g, 0.14 mol) and potassium tert-butoxide (17.3 g, 0.15 mol) in THF (500 ml), and the mixture is stirred at this temperature for 45 min. A solution of iodine (39.3 g, 0.15 mol) in THF (250 ml) is then added dropwise, and the reaction mixture is stirred at 90 C. for a further 30 min and subsequently thawed to 20 C. over the course of 3 h with stirring. For work-up, the mixture is hydrolysed using dist. water, sodium hydrogensulfite is added until the mixture decolourises, and the organic phase is separated off. The aqueous phase is extracted with methyl tert-butyl ether, and the combined organic phases are washed with dist. water, dried over sodium sulfate and evaporated in vacuo. The residue is purified by filtration through silica gel (100% heptane), giving 1-(4-butylphenylethynyl)-3-fluoro-4-iodo-2-propylbenzene (6) as a yellow oil.

1.4 Synthesis of 4-butyl-4-(4-butylphenylethynyl)-2-fluoro-3-propyl-[1,1;4,1]terphenyl (1)

(10) ##STR00044##

(11) 3 drops of dist. water are added to a mixture of 1-(4-butylphenylethynyl)-3-fluoro-4-iodo-2-propylbenzene (6) (2.8 g, 10.6 mmol), 4-butylbiphenyl-4-boronic acid (7) (CAS 145413-17-8) (5.0 g, 10.6 mmol), tris(dibenzylidene-acetone)dipalladium (196 mg, 0.2 mmol), 2-dicyclohexylphosphino-2,6-dimethoxybiphenyl (357 mg, 0.8 mmol) and potassium phosphate (12.2 g, 53.0 mmol) in 1,4-dioxane (100 ml), and the mixture is stirred at 100 C. for 16 h. The work-up is carried out by addition of methyl tert-butyl ether and dist. water. After the organic phase has been separated off, the aqueous phase is re-extracted with methyl tert-butyl ether. The combined organic phases are washed with dist. water and sodium chloride solution, dried over sodium sulfate and evaporated in vacuo. The residue is filtered through silica gel (heptane/chlorobutane 8:2), and the crude product is purified by recrystallisation from ethanol/toluene (2), giving 4-butyl-4-(4-butylphenylethynyl)-2-fluoro-3-propyl-[1,1;4,1]terphenyl (1) in the form of colourless crystals.

(12) MS (EI): m/e=502 (M.sup.+), 473 ([M-ethyl].sup.+), 459 ([M-propyl].sup.+), 430 ([M-propyl-ethyl].sup.+), 387 ([M-2 propyl-ethyl].sup.+).

(13) C 107 C. N 217 C. I;

(14) =0.8;

(15) n=0.362 and

(16) .sub.1=5490 Pa.Math.s.

Synthesis Example 2

Synthesis of 4-butyl-4-(4-butylphenylethynyl)-3-ethyl-[1,1;4,1]-terphenyl (9)

(17) ##STR00045##

(18) The synthesis of 4-butyl-4-(4-butylphenylethynyl)-3-ethyl-[1,1;4,1]-terphenyl) (9) is carried out starting from 4-butylbiphenyl-4-boronic acid (7) (CAS 145413-17-8) and 4-bromo-1-(4-butylphenylethynyl)-2-ethylbenzene (8) (CAS 1375922-99-8).

(19) ##STR00046##

(20) 3 drops of dist. water are added to a mixture of 4-bromo-1-(4-butylphenylethynyl)-2-ethylbenzene (9) (CAS 1375922-99-8) (5.0 g, 14.3 mmol), 4-butylbiphenyl-4-boronic acid (7) (CAS 145413-17-8) (3.7 g, 14.3 mmol), tris(dibenzylideneacetone)dipalladium (263 mg, 0.3 mmol), 2-dicyclohexylphosphino-2,6-dimethoxybiphenyl (480 mg, 1.1 mmol) and potassium phosphate (16.4 g, 71.3 mmol) in 1,4-dioxane (100 ml), and the mixture is stirred at 100 C. for 4 h. The work-up is carried out by addition of methyl tert-butyl ether and dist. water. After the organic phase has been separated off, the aqueous phase is re-extracted with methyl tert-butyl ether. The combined organic phases are washed with dist. water and sodium chloride solution, dried over sodium sulfate and evaporated in vacuo. The residue is filtered through silica gel (100% heptane), and the crude product is purified by recrystallisation from ethanol/toluene (2), heptane and isopropanol/toluene, giving 4-butyl-4-(4-butylphenylethynyl)-3-ethyl-[1,1;4,1]-terphenyl (9) in the form of colourless crystals.

(21) MS (EI): m/e=470 (M+), 455 ([M-methyl]+), 427 ([M-propyl]+), 412 ([M-propyl-methyl]+), 369 ([M-2 propyl-methyl]+).

(22) C 132 C. N 260 C. I;

(23) =1.8;

(24) n=0.413 and

(25) .sub.1=5250 Pa.Math.s.

Mixture Example 1

(26) A liquid-crystal medium M-1 having the composition and properties as indicated in the following table is prepared. Compound (1) originates from Synthesis Example 1.

(27) TABLE-US-00004 Composition Compound No. Abbreviation Physical properties 1 BCH-3FF 10.8% T(N, I) = 96 C. 2 BCH-5FF 9.0% n (20 C., 589.3 nm) = 0.124 3 ECCP-30CF3 4.5% (20 C., 1 kHz) = 4.9 4 ECCP-50CF3 4.5% .sub.1 (20 C.) = 166 mPa .Math. s 5 CBC-33F 1.8% 6 CBC-53F 1.8% 7 CBC-55F 1.8% 8 PCH-6F 7.2% 9 PCH-7F 5.4% 10 CCP-20CF3 7.2% 11 CCP-30CF3 10.8% 12 CCP-40CF3 6.3% 13 CCP-50CF3 9.9% 14 PCH-5F 9.0% 15 (1) 10.0% 100.0%

(28) This mixture is preferably used for applications in the microwave region, in particular for phase shifters, for example for phased-array antennae.

(29) For comparison, a medium C without component (1) is prepared from compound Nos. 1-14 of medium M-1, where compound Nos. 1-14 are present in the same relative amounts.

Mixture Example 2

(30) A liquid-crystal medium M-2 having the composition of M-1 is prepared as in the case of Mixture Example 1, with the difference that for M-2, compound (9) from Synthesis Example 2 is employed instead of compound (1).

(31) This mixture is likewise preferably used for applications in the microwave region, in particular for phase shifters, for example for phased array antennae.

(32) The results for the mixture examples are shown in the following table.

(33) TABLE-US-00005 TABLE Properties of mixtures M-1 and M-2, and C (for comparison) at 19 GHz (20 C.) Mixture .sub.r, .sub.r, tan .sub.,r tan .sub.,r M-1 2.56 2.25 0.121 0.0040 0.0107 11.3 M-2 2.57 2.25 0.124 0.0039 0.0110 11.2 C 2.56 2.29 0.107 0.0049 0.0126 8.5

(34) The tuneability and the material quality for the two mixtures M-1 and M-2 according to the invention are significantly improved compared with those of comparative mixture C.