Substituted polyphenyls

Abstract

The invention relates to substituted quinquephenyls of the formulae indicated in the claims and description. They are particularly suitable as UV-stabilizing component in liquid-crystalline media.

Claims

1. A compound of formula I, ##STR00029## which includes a biphenyl moiety of the formula A ##STR00030## in which L independently denotes F, Cl, CN, an alkyl group having 1 to 5 C atoms, an alkoxy group having 1 to 5 C atoms or an alkenyl group having 1 to 5 C atoms, a, b, c, d, e, independently of one another, denote 0, 1 or 2, where a+b+c+d+e>0, R.sup.1 and R.sup.2, independently of one another, denote a) an alkyl group having 1 to 15 C atoms, which may optionally be monosubstituted by CN or at least monosubstituted by halogen, where in each case one or more CH.sub.2 groups, in each case independently of one another, may also be replaced by CHCH, CFCF, CFCH, CHCF or CC, b) F, Cl, CN, NCS, SF.sub.5, CF.sub.3, CHF.sub.2, CH.sub.2F, OCF.sub.3, OCHF.sub.2, OCH.sub.2F, c) a radical of the formula ##STR00031## in which R.sup.0 is defined as R.sup.1 above, or d) a polymerisable group.

2. A compound according to claim 1, which is selected from the group of the compounds of the formulae IA and IB, ##STR00032## in which R.sup.1, R.sup.2, L, a, b, c and e independently have the meaning given in claim 1.

3. A compound according to claim 1, selected from the group of the compounds of the formulae ##STR00033## ##STR00034## in which the groups R.sup.1, R.sup.2 and L independently have the meaning given in claim 1.

4. A compound according to claim 1, wherein one, two or three of the substituents L present denote F, Cl or CH.sub.3.

5. A compound according to claim 1, wherein R.sup.1 and R.sup.2 denote a straight-chain, unbranched alkyl group having 1 to 8 C atoms, which may optionally be mono- or polysubstituted by halogen, where in each case one or more CH.sub.2 groups, in each case independently of one another, may be replaced by CHCH, CFCF, CFCH, CHCF or CC, or a group from definition b), c) or d) according to claim 1.

6. A compound according to claim 1, wherein one or more of the groups L denotes fluorine.

7. A method which comprises including in a liquid-crystal medium a compound according to claim 1 as a component for the stabilisation of said liquid-crystal medium.

8. A liquid-crystal medium comprising at least two liquid-crystalline compounds, characterised in that it comprises one or more compounds of the formula I according to claim 1.

9. A method which comprises including a liquid-crystal medium according to claim 8 in an electro-optical display.

10. An electro-optical display containing a liquid-crystal medium according to claim 8.

11. A process for the preparation of a liquid-crystalline medium according to claim 8, wherein one or more compounds of the formula I are mixed with one or more further liquid-crystalline compounds, and further compounds and additives are optionally added.

12. A compound according to claim 1, wherein each L independently denotes F or Cl.

Description

EXAMPLES

1. Synthesis of 3,2-dichloro-4,2-difluoro-4-pentyl-[1,1;4,4; 1,1;4,1]-quinquephenyl (4)

(1) ##STR00014##

(2) 1.1 g (8 mmol) of sodium metaborate are initially introduced in 4 ml of water, and 5 ml of THF, 0.1 g (0.14 mmol) of bis(triphenylphosphine)palladium(II) chloride and a few drops of hydrazinium hydroxide are subsequently added. 1.7 g (4.9 mmol) of the boronic ester and 2.5 g (5.2 mmol) of the triflate compound of the formulae indicated are then added, and the mixture is refluxed for 3 h, 0.5 g (1.4 mmol) of boronic ester are again added, and the mixture is refluxed for a further 12 h.

(3) The batch is cooled, methyl t-butyl ether (MTBE) and water are added, and the phases are separated. The aqueous phase is extracted once with MTBE, the combined organic phases are washed once with water and once with saturated sodium chloride solution, dried over sodium sulfate, filtered and evaporated in a rotary evaporator. The residue is purified by column chromatography (basic aluminium oxide; heptane/toluene) and subsequently recrystallised from ethanol/toluene or heptane, giving the product as a colourless solid.

(4) MS (EI): m/e (%)=556 (100, M.sup.+), 499 (81, [M-butyl].sup.+), 249.5 (35, [M-butyl].sup.2+).

(5) C 116 I

(6) =5.8

(7) n=0.333

(8) .sub.1=8782 mPa.Math.s

(9) The following are synthesised analogously or comparably:

2. 2,3-Dichloro-2,2,4-trifluoro-4-pentyl-[1,1;4,1;4,4;1,1]-quinquephenyl (2)

(10) ##STR00015##

(11) MS (EI): m/e (%)=574 (100, M.sup.+), 517 (82, [M-butyl].sup.+), 258.5 (31, [M-butyl].sup.2+).

(12) C 98 SmA 203 N 268.6 I

(13) =3.1

(14) n=0.309

(15) .sub.1=10837 mPa.Math.s

3. 4-Butyl-2-chloro-2,2-difluoro-4-pentyl-[1,1;4,1;4,4;1,1]-quinquephenyl (1)

(16) ##STR00016##

(17) MS (EI): m/e (%)=578 (100, M.sup.+), 535 (13, [M-propyl].sup.+), 521 (40, [M-butyl].sup.+), 478 (16, [M-butyl-propyl].sup.+), 239 (32, [M-butyl-propyl].sup.2+).

(18) C 101 SmA 252 N 330 I

(19) =1.0

(20) n=0.330

(21) .sub.1=11203 mPa.Math.s

4. 4-Butyl-2-chloro-2-fluoro-4-pentyl-[1,1;4,4;1,1;4,1]-quinquephenyl (3)

(22) ##STR00017##

(23) MS (EI): m/e (%)=560 (100, M.sup.+), 517 (13, [M-propyl].sup.+), 503 (50, [M-butyl].sup.+), 460 (14, [M-butyl-propyl].sup.+), 446 (19), 389 (11), 230 (33, [M-butyl-propyl].sup.2+).

(24) Tg 72 C 99 SmC 133 SmA 275 N 351 I

(25) =2.1

(26) n=0.345

(27) .sub.1=9534 mPa.Math.s

(28) Further example compounds:

5

(29) ##STR00018##

6

(30) ##STR00019##

7

(31) ##STR00020##

8

(32) ##STR00021##

9

(33) ##STR00022##

10

(34) ##STR00023##

11

(35) ##STR00024##

12

(36) ##STR00025##

13

(37) ##STR00026##

14

(38) ##STR00027##

15

(39) ##STR00028##

Use Examples: Increasing the Stability of a Liquid-Crystal Mixture to UV Exposure

(40) In each case, 0, 0.1 and 1% by weight of the example compounds indicated are added to the following mixture, which is then subjected to a light test for 1 h or 24 h. The light test is carried out using an MTS Atlas Suntest CPS+ instrument. The VHR (voltage holding ratio) measurement value is determined at 100 C.

(41) TABLE-US-00004 TABLE 1 Test mixture for the light test. Component Proportion (% by weight) PCH-53 18% CCH-35 9% CCP-2F.F.F 10.8% CCP-3F.F.F 9% CCP-5F.F.F 7.2%.sup. ECCP-3F.F 9% ECCP-5F.F 9% CCP-30CF3.F 9% CCP-50CF3.F 9% PP(F)UQU-3-F 10%

(42) The measurement results are shown in Table 2 below.

(43) TABLE-US-00005 TABLE 2 VHR measurement values of the test mixture with various additives and variation of the added amount. Measurement after light test (UV exposure) for 1 and 24 h. No. Additive (content) VHR (24 h) [%] .sup.(*.sup.) VHR (1 h) [%] .sup.(*.sup.) 1 None (0% by weight) 55 79 2 1 (0.1% by weight) 71 3 1 (1% by weight) 74 4 2 (0.1% by weight) 70 5 2 (1% by weight) 75 6 3 (0.1% by weight) 78 7 3 (1% by weight) 89 8 4 (0.1% by weight) 77 9 4 (1% by weight) 88 .sup.(*.sup.) The VHR (voltage holding ratio) value before the light test is about 99%.

(44) The table also shows one reference value each after 1 and 24 h for the mixture without additive. The VHR values are already significantly improved by a small amount of additives, i.e. the mixture is protected against light/UV exposure. The effect is enhanced by increasing the amount of additive.