Compounds and liquid-crystalline medium

Abstract

Compounds of formula I, and liquid-crystalline media, preferably having a nematic phase and negative dielectric anisotropy, comprising: a) one or more compounds of formula I ##STR00001## and one or more other compounds selected from: b) one or more compounds of formula II ##STR00002## and/or c) one or more compounds selected from compounds of formulae III-1 to III-4 and B ##STR00003## Use thereof in electro-optical displays, particularly in active-matrix displays based on the VA, ECB, PALC, FFS or IPS effect and use of compounds of formula I for stabilisation of liquid-crystalline media which comprise one or more compounds of formula II and/or one or more compounds selected from compounds of formulae III-1 to III-4 and B.

Claims

1. A liquid-crystalline medium, comprising a) one or more compounds of the formula I ##STR00238## in which R.sup.11 on each occurrence, independently of one another, denotes H, F, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one CH.sub.2 group or, if present, a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and one or, if present, a plurality of CH.sub.2 groups may be replaced by CHCH or CC, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.12 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.13 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6-12 C atoms, R.sup.14 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6-12 C atoms, R.sup.15 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms, in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, S.sup.11 and S.sup.12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, in which one CH.sub.2 group or, if present, a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or denote a single bond, Y.sup.11 to Y.sup.14 each, independently of one another, denote methyl or ethyl, Z.sup.11 to Z.sup.14 on each occurrence, independently of one another, denote O, (CO), O(CO), (CO)O, O(CO)O, (NR.sup.13), or NR.sup.13(CO), or additionally a single bond if S.sup.11 is a single bond, provided that both Z.sup.11 and Z.sup.12 do not simultaneously denote O, and, provided that, if S.sup.12 is a single bond, both Z.sup.13 and Z.sup.14 do not simultaneously denote O, and, provided that if X.sup.11[R.sup.11].sub.o is a single bond, both Z.sup.12 and Z.sup.13 do not simultaneously denote O, X.sup.11 denotes C, O. denotes an oxide radical, p denotes 1 or 2, o for formula I, denotes (3p), and, if p is 2, n for formula I, denotes an integer from 2 to 4, and m for formula I, denotes (4n), and, if p is 1, n for formula I, denotes an integer from 5 to 10, and m for formula I, denotes (10n), and ##STR00239## denotes an organic radical having (m+n) bonding sites, and where, in the case where p=1, X.sup.11[R.sup.11].sub.o may alternatively also denote a single bond, and one or more further compounds selected from: b) one or more compounds of the formula II ##STR00240## in which R.sup.21 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms and R.sup.22 denotes an unsubstituted alkenyl radical having 2 to 7 C atoms, and/or c) one or more compounds selected from the group of the compounds of the formulae III-1 to III-4 and B, ##STR00241## in which R.sup.31 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, R.sup.32 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, m, n and o, for formulae III-1 to III-4, each, independently of one another, denote 0 or 1, R.sup.B1 and R.sup.B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and L.sup.B1 and L.sup.B2 each, independently of one another, denote F or Cl.

2. Medium according to claim 1, wherein the total concentration of the compounds of the formula I in the medium as a whole is 1 ppm or more to 2000 ppm or less.

3. Medium according to claim 1, which comprises a compound of the formula II in which R.sup.21 denotes n-propyl and R.sup.22 denotes vinyl.

4. Medium according to claim 3, wherein the total concentration of the compounds of the formula II in the medium as a whole is from 25% to 45%.

5. Medium according to claim 1, which comprises one or more compounds of the formula B.

6. Medium according to claim 1, which comprises one or more compounds of the formula III-4.

7. Medium according to claim 1, which additionally comprises one or more chiral compounds.

8. A compound of the formula I ##STR00242## in which R.sup.11 on each occurrence, independently of one another, denotes H, F, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one CH.sub.2 group or, if present, a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and one or, if present, a plurality of CH.sub.2 groups may be replaced by CHCH or CC, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.12 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.13 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6-12 C atoms, R.sup.14 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6-12 C atoms, R.sup.15 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms, in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, S.sup.11 and S.sup.12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, in which one CH.sub.2 group or, if present, a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or denote a single bond, Y.sup.11 to Y.sup.14 each, independently of one another, denote methyl or ethyl, Z.sup.11 to Z.sup.14 on each occurrence, independently of one another, denote O, (CO), O(CO), (CO)O, O(CO)O, (NR.sup.13), or NR.sup.13(CO), or additionally a single bond if S.sup.11 is a single bond, provided that both Z.sup.11 and Z.sup.12 do not simultaneously denote O, and, provided that, if S.sup.12 is a single bond, both Z.sup.13 and Z.sup.14 do not simultaneously denote O, and, provided that if X.sup.11[R.sup.11].sub.o is a single bond, both Z.sup.12 and Z.sup.13 do not simultaneously denote O, X.sup.11 denotes C, p denotes 1 or 2, o for formula I, denotes (3p), and, if p is 2, n for formula I, denotes an integer from 2 to 4, and m for formula I, denotes (4n), and, if p is 1, n for formula I, denotes an integer from 5 to 10, and m for formula I, denotes (10n), and ##STR00243## denotes an organic radical having (m+n) bonding sites, and where, in the case where p=1, X.sup.11[R.sup.11].sub.o may alternatively also denote a single bond.

9. Compound of the formula I according to claim 8 in which p denotes 2.

10. Compound of the formula I according to claim 9, selected from the group of the compounds of the formulae I-1 to I-9: ##STR00244## ##STR00245## ##STR00246## ##STR00247##

11. Electro-optical display or electro-optical component, which contains a liquid-crystalline medium according to claim 1.

12. Display according to claim 11, which is based on the IPS, FFS, VA or ECB effect.

13. Display according to claim 11, which contains an active-matrix addressing device.

14. Process for the preparation of a liquid-crystalline medium according to claim 1, comprising mixing one or more compounds of the formula I with one or more compounds of the formula II and/or one or more compounds selected from the group of the compounds of the formulae III-1 to III-4 or formula B.

15. Process for the stabilisation of a liquid-crystalline medium, which comprises providing one or more compounds of the formula I of claim 8, and optionally one or more compounds selected from the group of the compounds of the formulae OH-1 to OH-6, ##STR00248## to the medium.

16. Process for the preparation of a compound of the formula I according to claim 8, comprising reacting an alcohol containing two 1-oxy-2,2,6,6-tetramethylpiperidin-4-yl groups with a derivatised ring structure that will provide a compound of the formula I.

17. The process of claim 16, wherein the derivatised ring structure has dicarboxylic acid dihalide or a tetracarboxylic acid tetrahalide derivatisation.

18. The medium of claim 1, wherein, in formula I, either: p=1 and n denotes an integer from 5 to 8, or p=2 and n denotes an integer from 2 to 3.

19. The compound of claim 8, wherein, in formula I, either: p=1 and n denotes an integer from 5 to 8, or p=2 and n denotes an integer from 2 to 3.

20. A liquid-crystalline medium which comprises: one or more compounds of the formulae I-1 to I-9: ##STR00249## ##STR00250## ##STR00251## ##STR00252## ##STR00253## and b) one or more compounds selected from the group of the compounds of the formula B, ##STR00254## in which R.sup.B1 and R.sup.B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and L.sup.B1 and L.sup.B2 each, independently of one another, denote F or Cl.

21. A liquid-crystalline medium comprising: a) one or more compounds of the formula I ##STR00255## in which R.sup.11 on each occurrence, independently of one another, denotes H, F, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one CH.sub.2 group or, if present, a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and one or, if present, a plurality of CH.sub.2 groups may be replaced by CHCH or CC, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.3, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.12 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl chain having 1-20 C atoms, in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, R.sup.13 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6-12 C atoms, R.sup.14 on each occurrence, independently of one another, denotes H, a straight-chain or branched alkyl or acyl group having 1 to 10 C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6-12 C atoms, R.sup.15 on each occurrence, independently of one another, denotes a straight-chain or branched alkyl group having 1 to 10 C atoms, in which one CH.sub.2 group or a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, S.sup.11 and S.sup.12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, in which one CH.sub.2 group or, if present, a plurality of CH.sub.2 groups may be replaced by O or C(O), but two adjacent CH.sub.2 groups cannot be replaced by O, and in which one H atom or a plurality of H atoms may be replaced by F, OR.sup.13, N(R.sup.13)(R.sup.14) or R.sup.15, or denote a single bond, Y.sup.11 to Y.sup.14 each, independently of one another, denote methyl or ethyl, Z.sup.11 to Z.sup.14 on each occurrence, independently of one another, denote O, (CO), O(CO), (CO)O, O(CO)O, (NR.sup.13), or NR.sup.13(CO), or additionally a single bond if S.sup.11 is a single bond, provided that both Z.sup.11 and Z.sup.12 do not simultaneously denote O, and, provided that, if S.sup.12 is a single bond, both Z.sup.13 and Z.sup.14 do not simultaneously denote O, and, provided that if X.sup.11[R.sup.11].sub.o is a single bond, both Z.sup.12 and Z.sup.13 do not simultaneously denote O, X.sup.11 denotes C, O. denotes an oxide radical, p denotes 1 or 2, o for formula I, denotes (3p), and, if p is 2, n for formula I, denotes an integer from 2 to 4, and m for formula I, denotes (4n), and, if p is 1, n for formula I, denotes an integer from 3 to 10, and m for formula I, denotes (10n), provided that either: p=1 and n denotes an integer from 5 to 8, or p=2 and n denotes an integer from 2 to 3, and ##STR00256## denotes an organic radical having (m+n) bonding sites, and where, in the case where p=1, X.sup.11[R.sup.11].sub.o may alternatively also denote a single bond, and b) one or more compounds selected from the group of the compounds of the formula B, ##STR00257## in which R.sup.B1 and R.sup.B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and L.sup.B1 and L.sup.B2 each, independently of one another, denote F or Cl.

Description

EXAMPLES

(1) The following examples explain the present invention without restricting it in any way. However, the physical properties make it clear to the person skilled in the art what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

Substance Examples

(2) The following substances are preferred substances of the formula I in accordance with the present application or substances of the formula I preferably to be employed in accordance with the present application.

(3) ##STR00212## ##STR00213## ##STR00214## ##STR00215##

(4) The following examples explain the present invention without limiting it in any way. However, the physical properties make it clear to the person skilled in the art which properties are to be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

Synthesis Example 1: Synthesis of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-{3-[2,5-bis({4-butyl-5-[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl})phenyl]propyl}-2-butylpropanedioate 1

Substance Example 1

(5) ##STR00216##

Step 1.1: Synthesis of 3-[3,4-bis(3-hydroxypropyl)phenyl]propan-1-ol A

(6) ##STR00217##

(7) 51.34 g (484.0 mmol) of anhydrous sodium carbonate are dissolved in 171.7 ml of water. A solution of 25.0 g (79.0 mmol) of 1,2,4-tribromobenzene and 67.7 g (476 mmol) of 2-butoxy-1,2-oxaborolane in 965.2 ml of tetrahydrofuran (THF) is added, 1.65 ml (11.9 mmol) of triethylamine are added, and the mixture is stirred and degassed for 30 min. using a stream of argon. 1.40 g (7.49 mmol) of palladium(II) chloride (59% of palladium, anhydrous) and 1.85 g (3.97 mmol) of 2-dicyclohexylphoshino-2,6-diisopropoxy-1,1-biphenyl are added, and the reaction mixture is stirred under reflux for 18 hours. The reaction mixture is allowed to cool to room temperature (RT), water and methyl tertiary-butyl ether (MTBE) are added, and the phases are separated. The water phase is extracted with MTBE, and the combined organic phases are washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo. The product is obtained as a yellowish oil and is filtered through silica gel with a mixture of ethyl acetate (EA) and methanol (9:1). The product fractions are combined and evaporated in vacuo, giving the reaction product as a pale-yellow oil. The product is characterised by means of NMR spectroscopy.

(8) .sup.1H NMR (500 MHz, DMSO-d6)

(9) =1.66 (m.sub.c, 6H, CH.sub.2), 2.42-2.69 (m.sub.(superimposed with DMSO), 6H, CH.sub.2), 3.36-3.49 (m, 6H, CH.sub.2), 4.44 (t, J=5.15 Hz, 1H), 4.48 (m.sub.c, 2H), 6.92 (dd, J=1.7, 7.72 Hz, 1H), 6.95 (d, J=1.53 Hz, 1H), 7.03 (d, J=7.7 Hz, 1H).

Step 1.2: Synthesis of 1,2,4-tris(3-iodopropyl)benzene B

(10) ##STR00218##

(11) 30.2 ml (138 mmol) of triphenylphosphine are dissolved in 513 ml of acetonitrile, and a solution of 34.92 g (138.0 mmol) of iodine in 513 ml of acetonitrile is added dropwise with gentle cooling. An orange suspension forms during this addition. When the addition is complete, the mixture is stirred for a further 10 min. 13.3 g (197 mmol) of imidazole are added, and a solution of 10.0 g (39.3 mmol) of triol A in 100 ml of acetonitrile is subsequently added dropwise (a clear, yellow solution forms during this addition). The reaction solution is stirred at RT for 3 hours (h) and carefully poured into a cold sodium thiosulfate solution (decolouration occurs), and heptane is added. After washing by stirring, the phases are separated, the water phase is extracted with heptane, and the combined organic phases are washed with water, dried over sodium sulfate, filtered and evaporated in vacuo. The crude product is filtered through silica gel with heptane (H) and ethyl acetate (8:2), and evaporation of the product fractions gives the product as a colourless oil. The product is characterised by means of mass spectrometry.

(12) MS (EI)=582.0

Step 1.3: Synthesis of 2-butylpropanedioyl Dichloride C

(13) ##STR00219##

(14) 76.00 g (474.5 mmol) of 2-butylmalonic acid are initially introduced in the reaction apparatus and warmed to 40 C. 90.00 ml (1.240 mol) of thionyl chloride are then added dropwise over the course of about 30 min. (care, evolution of gas), and the mixture is stirred at room temperature (RT) for a further 5 hours (h). The evolution of gas decreases significantly within this time span. The reaction solution is then stirred at 50 C. for 18 h and subsequently at 70 C. for 5 h. On each increase in temperature, slight evolution of gas re-occurs. The reaction mixture is then cooled to room temperature and taken up in 300 ml of dry toluene, and excess thionyl chloride is separated off by distillation together with the toluene (8 mbar and RT to max. bath temperature of 80 C.), giving the crude product as a brownish liquid, which can be employed directly in the next synthesis step.

Step 1.4: Synthesis of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-butylpropanedioate D

(15) ##STR00220##

(16) 45.3 g (262.9 mmol) of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (free radical) and 40.1 ml (289.15 mmol) of triethylamine are dissolved in 419 ml of dichloromethane (DCM) and cooled to 11 C. A solution of 25.9 g (131.4 mmol) of the acid chloride C in 252 ml of DCM is then added dropwise at 11 C. to 6 C. over the course of 1.5 hours (h). The reaction mixture is stirred at max. 0 C. for about 3 h, slowly thawed and stirred at room temperature (RT) for 18 h. Saturated NaHCO.sub.3 solution is added at 3-6 C. with cooling, the mixture is stirred briefly, and the phases are separated. The water phase is extracted with DCM, and the organic phases are combined, washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo. The crude product obtained (orange solid) is filtered through silica gel with DCM/MTBE (9:1), and the product fractions are evaporated in vacuo, giving the product as orange crystals.

Step 1.5: Synthesis of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-{3-[2,5-bis({4-butyl-5-[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl})phenyl]propyl}-2-butylpropanedioate 1

(17) ##STR00221##

(18) 0.31 g (7.80 mmol) of sodium hydride (60% suspension in paraffin oil) is suspended in 9.7 ml of N,N-dimethylformamide (DMF). 3.75 g (7.87 mmol) of a solution of the bisradical D dissolved in 29.0 ml DMF are added dropwise with gentle cooling (evolution of gas), and the mixture is stirred at RT for 1 hour. 1.40 g (2.39 mmol) of trisiodide B are added dropwise to the reaction solution (5 C. evolution of heat over 5 minutes), and the mixture is stirred at RT for 3 h. The reaction mixture is carefully added to ammonium chloride solution and extracted with MTBE. The phases are separated, the water phase is extracted with MTBE, washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo. The orange crude product obtained is filtered through silica gel with ethyl acetate/heptane (1:1), and the product fractions are evaporated in vacuo, giving the product as an orange solid which foams up in a glass-like manner. The product has the following properties.

(19) Phases: glass transition temperature (TG)=23.5 C., decomposition from 150 C.

(20) MS (APCI)=1605.1 [M+H.sup.+].

Synthesis Example 2: Synthesis of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-(3-{3,5-bis[({4-butyl-5-[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl}oxy)carbonyl]benzoyloxy}propyl)-2-butylpropanedioate 2

(21) ##STR00222##

Step 2.1: Synthesis of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-butyl-2-[3-(oxan-2-yloxy)propyl]propanedioate E

(22) ##STR00223##

(23) 3.20 g (80.4 mmol) of sodium hydride (60% suspension in paraffin oil) are suspended in 30 ml of DMF. A solution of 32.40 g (69.14 mmol) of bisradical D (from the synthesis of compound 1) in 300 ml of DMF is added dropwise to the reaction solution with gentle cooling (evolution of gas), and the mixture is stirred at RT for 1 h. A solution of 19.0 g (85.16 mmol) of 2-(3-bromopropoxy)tetrahydropyran in 200 ml of DMF is then added dropwise at RT (0.5 C. evolution of heat). For degassing of the reaction mixture before an increase in temperature, a gentle stream of argon is passed through the reaction mixture by means of an immersed Pasteur pipette for 30 minutes, and the mixture is subsequently stirred at 35 C. for 18 h. The reaction solution is allowed to cool to RT, added to saturated NaCl solution and extracted with MTBE, and the phases are separated. The aqueous phase is extracted with MTBE, and the organic phases are combined, washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo, giving the crude product as a red oil, which, for purification, is filtered through silica gel with DCM/MTBE (9:1), giving the product as a red oil.

Step 2.2: Synthesis of bis(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl) 2-butyl-2-(3-hydroxypropyl)propanedioate F

(24) ##STR00224##

(25) 36.5 g (56.1 mmol) of bisradical E and 9.50 g (55.2 mmol) of toluene-4-sulfonic acid monohydrate are dissolved in a mixture of 500 ml of methanol and 50 ml of water, and the mixture is stirred at 40 C. for 5 h. The reaction solution is cooled to RT and adjusted to pH=9 using NaHCO.sub.3 solution with cooling and evaporated in vacuo. The aqueous residue is extracted with MTBE, and the combined organic phases are washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo, giving a red oil, which is dissolved in 250 ml of DCM, 6.00 g (55.6 mmol) of MnO.sub.2 are added, and the mixture is stirred at RT for 1 h. (In the case of removal of the THP protecting group, the free radical is in some cases also converted into the OH compound, which is reversed using MnO.sub.2). The reaction mixture is filtered through silica gel with DCM and evaporated in vacuo. The crude product obtained is filtered through silica gel with DCM/MTBE (7:3), and the product fractions are evaporated in vacuo to give a red oil.

Step 2.3: Synthesis of bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-(3-{3,5-bis[({4-butyl-5-[(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl}oxy)carbonyl]-benzoyloxy}propyl)-2-butylpropanedioate 2

(26) ##STR00225##

(27) 6.70 g (11.7 mmol of F and 50.0 mg (0.41 mmol) of 4-(dimethylamino)pyridine are dissolved in 100 ml of dichloromethane at RT, and the mixture is cooled to 4 C. 5.00 ml (36.1 mmol) of triethylamine are then added, and a solution of 1.00 g (3.77 mmol) of 1,3,5-benzenetricarbonyl chloride in 10 ml of DCM is subsequently added dropwise at 3-4 C. When the evolution of heat is complete, the mixture is allowed to warm to RT and is subsequently stirred at RT for 18 h. Ammonium chloride solution is then added with cooling, the mixture is stirred briefly, the phases are separated, and the aqueous phase is extracted with DCM. The combined organic phases are washed with dilute NaCl solution (better phase separation), dried over sodium sulfate, filtered and evaporated in vacuo, giving the reaction product as a red, solidifying foam. For further purification, the product is filtered through silica gel with DCM/MTBE (9:1 to 85:15), and the product fractions are evaporated in vacuo. The reaction product obtained is a red, solidifying foam. It has the following properties.

(28) Phases: T.sub.g (glass transition temperature) 52 C., C (melting point) 57 C. I, decomposition >175 C.

(29) MS (APCI)=1734.

(30) The following compounds are prepared analogously to the synthesis sequence(s) described.

Substance/Synthesis Example 3

(31) ##STR00226##

(32) Phases: T.sub.g (glass transition temperature) 3 C. I (isotropic), decomposition >100 C.

Substance/Synthesis Example 4

(33) ##STR00227##

(34) Phases: T.sub.g (glass transition temperature) 5 C. I (isotropic), decomposition >180 C.

Substance/Synthesis Example 5

(35) ##STR00228##

(36) Phases: T.sub.g (glass transition temperature) 5 C. I (isotropic), decomposition >170 C.

Substance/Synthesis Example 6

(37) ##STR00229##

(38) Phases: T.sub.g (glass transition temperature) 27 C. I (isotropic).

Substance/Synthesis Example 7

(39) ##STR00230##

Substance/Synthesis Example 8

(40) ##STR00231##

(41) Phases: T.sub.g (glass transition temperature) 3 C. I (isotropic).

Substance/Synthesis Example 9

(42) ##STR00232##

Mixture Examples

(43) Liquid-crystal mixtures having the compositions and properties as indicated in the following tables are prepared and investigated. The improved stability of the mixtures comprising compounds of the formula I is shown by comparison with unstabilised base mixtures as reference (Ref.).

Examples 1.1 to 1.3 and Corresponding Comparative Examples

(44) Mixture (M-1) below is prepared and investigated.

(45) TABLE-US-00008 Mixture M-1 Composition Compound Concentration No. Abbreviation /% by weight 1 CPP-3-2 4.5 2 CC-3-V 23.5 3 CCH-301 4.0 4 CCY-3-O2 4.0 5 CCY-3-O3 7.0 6 CCY-4-O2 8.0 7 CLY-3-O2 8.0 8 CPY-2-O2 7.0 9 CPY-3-O2 11.0 10 CY-3-O2 11.0 11 PY-3-O2 12.0 100.0 Physical properties T(N, I) = 86 C. n.sub.e(20 C., 589 nm) = 1.5962 n(20 C., 589 nm) = 0.1118 .sub.(20, 1 kHz) = 8.0 (20, 1 kHz) = 4.3 .sub.1(20 C.) = 143 mPa .Math. s k.sub.11(20 C.) = 15.0 pN K.sub.22(20 C.) = t.b.d. pN k.sub.33(20 C.) = 16.7 pN V.sub.0(20 C.) = 2.08 V Note: Here, as throughout the present application, t.b.d. means to be determined, unless indicated otherwise.

(46) Firstly, the stability of the voltage holding ratio of mixture (M-1) itself is determined. The stability of mixture M-1 to irradiation with a backlight is investigated in a test cell having an alignment material for planar alignment, with a layer thickness of 6.0 m and flat ITO electrodes. To this end, the mixture is, or the mixtures are, subjected to a test for exposure to a backlight. To this end, the stability of the corresponding test cells to illumination with an LED (light-emitting diode) backlight for LCDs is investigated. To this end, corresponding test cells are filled and sealed. These cells are then exposed to illumination with a commercial LCD backlight for various times (168 h, 336 h, 500 h and 1000 h). There is no additional heating besides the heat generated by the backlight. The voltage holding ratio is then in each case determined after 5 minutes at a temperature of 100 C. The results are compiled in the following table, Table 1a.

(47) Here, as below, six test cells are filled and investigated for each individual mixture. The values indicated are the average of the six individual values.

(48) The relative deviations of the voltage holding ratio values in various measurement series are typically in the range from about 3 to 4%.

(49) 100 ppm of the reference compounds R-1 to R-3

(50) ##STR00233##
are added to each of three further parts of mixture M-1, and 100 ppm of in each case one of the three compounds I-1 to 1-3

(51) ##STR00234## ##STR00235##
are added to each of three further parts of mixture M-1, and the stability of the resultant mixtures (C-1.1, C-1.2 and C-1.3, as well as M-1.1, M-1.2 and M-1.3) is investigated as described above. The results are shown in the tables below, Tables 1a to 1d.

(52) TABLE-US-00009 TABLE 1a VHR(t)/% @ c(stab.) 100 C., 60 Hz Ex. Mixture Stabiliser /ppm t = 0 h t = 168 h t = 336 h (Ref.) M-1 none 0 80.4 59.1 58.2 C1.1 C-1-1 R-1 100 t.b.d. t.b.d. t.b.d. C1.2 C-1-2 R-2 100 74.1 66.8 66.6 C1.3 C-1-3 R-3 100 73.1 73.0 72.4 M1.1 M-1-1 I-1 100 72.6 74.9 74.0 M1.2 M-1-2 I-2 100 71.3 76.8 74.4 M1.3 M-1-3 I-3 100 72.7 77.7 75.3

(53) TABLE-US-00010 TABLE 1b VHR(t)/% @ c(stab.) 100 C., 60 Hz Ex. Mixture Stabiliser /ppm t = 0 h t = 168 h t = 336 h (Ref.) M-1 none 0 80.4 67.1 61.7 C1.1 C-1-1 R-1 100 t.b.d. t.b.d. t.b.d. C1.2 C-1-2 R-2 100 74.1 75.1 69.9 C1.3 C-1-3 R-3 100 73.1 77.9 75.7 M1.1 M-1-1 I-1 100 72.6 81.0 78.8 M1.2 M-1-2 I-2 100 71.3 81.3 80.5 M1.3 M-1-3 I-3 100 72.7 82.2 81.2

(54) TABLE-US-00011 TABLE 1c VHR(t)/% @ c(stab.) 60 C., 1 Hz Ex. Mixture Stabiliser /ppm t = 0 h t = 168 h t = 336 h (Ref.) M-1 none 0 88.9 79.4 68.9 C1.1 C-1-1 R-1 100 t.b.d. t.b.d. t.b.d. C1.2 C-1-2 R-2 100 78.2 78.0 70.0 C1.3 C-1-3 R-3 100 78.2 86.2 82.6 M1.1 M-1-1 I-1 100 77.3 90.3 87.6 M1.2 M-1-2 I-2 100 79.7 90.1 89.7 M1.3 M-1-3 I-3 100 78.5 88.1 86.9

(55) TABLE-US-00012 TABLE 1d VHR(t)/% @ c(stab.) 60 C., 1 Hz Ex. Mixture Stabiliser /ppm t = 0 h t = 500 h t = 1.000 h (Ref.) M-1 none 0 88.9 73.9 55.5 C1.1 C-1-1 R-1 100 t.b.d. t.b.d. t.b.d. C1.2 C-1-2 R-2 100 78.2 74.5 61.6 C1.3 C-1-3 R-3 100 78.2 87.4 78.2 M1.1 M-1-1 I-1 100 77.3 90.1 82.0 M1.2 M-1-2 I-2 100 79.7 91.4 83.8 M1.3 M-1-3 I-3 100 78.5 89.9 82.7

Examples 2.1.1 to 2.6.3 and Corresponding Comparative Examples

(56) The following mixture (M-2) is prepared and investigated.

(57) TABLE-US-00013 Mixture M-2 Composition Compound Concentration No. Abbreviation /% by weight 1 CY-3-O2 12.0 2 CY-3-O4 2.0 3 CY-5-O2 12.0 4 CCY-3-O1 6.0 5 CCY-3-O2 8.0 6 CCY-4-O2 8.0 7 CPY-2-O2 9.0 8 CPY-3-O2 9.0 9 PYP-2-3 5.0 10 CC-3-V1 5.0 11 CC-3-V 19.0 12 CPP-3-2 5.0 100.0 Physical properties T(N, I) = 86.5 C. n.sub.e(20 C., 589 nm) = 1.5924 n(20 C., 589 nm) = 0.1092 .sub.(20, 1 kHz) = 7.9 (20, 1 kHz) = 4.2 .sub.1(20 C.) = 155 mPa .Math. s k.sub.11(20 C.) = 14.6 pN k.sub.33(20 C.) = 16.6 pN V.sub.0(20 C.) = 2.08 V

(58) This mixture, mixture M-2, is investigated below with respect to the stability of its voltage holding ratio to irradiation with UV radiation. To this end, this mixture is also divided into several parts.

(59) Firstly, the stability of mixture (M-1) itself is determined. To this end, the stability of mixture M-1 to UV exposure is investigated in a test cell having an appropriate polyimide as alignment material for planar alignment, with a layer thickness of 6.0 m and flat ITO electrodes. To this end, corresponding test cells are irradiated in the Suntest for 30 min. The voltage holding ratio is then in each case determined after 5 minutes at a temperature of 100 C. The addressing frequency (or measurement frequency) here is 60 Hz, unless indicated otherwise in detail. The results are compiled in Table 2a.

(60) Then, for comparison, 100 ppm, 300 ppm or 600 ppm of the reference compound R-2 are added to three parts of mixture M-2, and the resultant mixtures (C-1.1, C-1.2 and C-1.3) are investigated as described above. The results are compiled in the following table, Table 2a.

(61) 100 ppm, 300 ppm or 600 ppm of in each case one of compounds I-1 to I-3, as indicated above, and of the following compounds I-4 to I-6

(62) ##STR00236## ##STR00237##
are then in each case added to sets of three further parts of mixture M-2, and the stability of the resultant mixtures (C-1.1, C-1.2 and C-1.3, as well as M-1.1, M-1.2 and M-1.3) is investigated as described above. The results are shown in the following tables, Tables 2a and 2b.

(63) TABLE-US-00014 TABLE 2a VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 none 0 76.2 66.1 C2.1 C-2-1.1 R-2 100 75.6 65.5 C2.2 C-2-1.2 R-2 300 t.b.d. t.b.d. C2.3 C-2-1.3 R-2 600 t.b.d. t.b.d. M2.1.1 M-2-1.1 I-1 100 75.5 65.8 M2.1.2 M-2-1.2 I-1 300 73.6 64.7 M2.1.3 M-2-1.3 I-1 600 69.1 65.1 M2.2.1 M-2-2.1 I-2 100 75.2 68.4 M2.2.2 M-2-2.2 I-2 300 76.2 68.9 M2.2.3 M-2-2.3 I-2 600 73.8 68.9 M2.3.1 M-2-3.1 I-3 100 72.4 73.5 M2.3.2 M-2-3.2 I-3 300 74.9 75.1 M2.3.3 M-2-3.3 I-3 600 72.2 73.4 M2.4.1 M-2-4.1 I-3 100 73.0 73.1 M2.4.2 M-2-4.2 I-4 300 71.0 71.7 M2.4.3 M-2-4.3 I-4 600 71.7 71.1 M2.5.1 M-2-5.1 I-5 100 7.4 72.6 M2.5.2 M-2-5.2 I-5 300 73.1 72.0 M2.5.3 M-2-5.3 I-5 600 72.3 72.2 M2.6.1 M-2-6.1 I-6 100 74.2 73.3 M2.6.2 M-2-6.2 I-6 300 73.1 71.7 M2.6.3 M-2-6.3 I-6 600 t.b.d. t.b.d.

(64) It is readily evident here that compounds I-1 to 1-6 exhibit clearly stabilising properties, even in relatively low concentrations.

(65) The investigations described above are repeated at a temperature of 60 C. and an addressing/measurement frequency of 10 Hz. The results are compiled in the following table, Table 2b.

(66) TABLE-US-00015 TABLE 2b VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 none 0 90.7 71.7 C2.1 C-2-1.1 R-2 100 84.1 75.2 C2.2 C-2-1.2 R-2 300 t.b.d. t.b.d. C2.3 C-2-1.3 R-2 600 t.b.d. t.b.d. M2.1.1 M-2-1.1 I-1 100 86.4 82.1 M2.1.2 M-2-1.2 I-1 300 85.7 83.8 M2.1.3 M-2-1.3 I-1 600 85.1 79.7 M2.2.1 M-2-2.1 I-2 100 84.2 81.4 M2.2.2 M-2-2.2 I-2 300 83.6 80.9 M2.2.3 M-2-2.3 I-2 600 83.9 80.3 M2.3.1 M-2-3.1 I-3 100 81.7 82.1 M2.3.2 M-2-3.2 I-3 300 83.0 81.5 M2.3.3 M-2-3.3 I-3 600 77.1 80.9 M2.4.1 M-2-4.1 I-3 100 81.9 81.23 M2.4.2 M-2-4.2 I-4 300 77.3 76.4 M2.4.3 M-2-4.3 I-4 600 76.9 77.1 M2.5.1 M-2-5.1 I-5 100 92.3 83.5 M2.5.2 M-2-5.2 I-5 300 84.0 81.5 M2.5.3 M-2-5.3 I-5 600 86.2 79.6 M2.6.1 M-2-6.1 I-6 100 86.6 82.8 M2.6.2 M-2-6.2 I-6 300 88.2 81.5 M2.6.3 M-2-6.3 I-6 600 t.b.d. t.b.d.

Example 3

(67) The following mixture (M-3) is prepared and investigated.

(68) TABLE-US-00016 Mixture M-3 Composition Compound Concentration No. Abbreviation /% by weight 1 B-2O-O5 4.0 2 CY-3-O2 10.0 3 CY-5-O2 1.5 4 CCY-3-O2 10.0 5 CCY-5-O2 7.0 6 CPY-2-O2 10.0 7 CPY-3-O2 10.0 8 PYP-2-3 5.5 9 CC-3-V 32.0 10 CC-3-V1 10.0 100.0 Physical properties T(N, I) 85.0 C. n.sub.e(20 C., 589 nm) = 1.5868 n(20 C., 589 nm) = 0.1047 .sub.(20, 1 kHz) = 6.9 (20, 1 kHz) = 3.4 .sub.1(20 C.) = 108 mPa .Math. s k.sub.11(20 C.) = 14.6 pN k.sub.33(20 C.) = 17.4 pN V.sub.0(20 C.) = t.b.d. V V.sub.10(20 C.) = t.b.d. V

(69) As described in Examples 1 and 2, mixture M-3 is also divided into several parts and its stability to exposure to an LCD backlight and to a UV source is investigated as such and with various added compounds in a test cell with an alignment material for planar alignment and flat ITO electrodes.

Example 4

(70) The following mixture (M-4) is prepared and investigated.

(71) TABLE-US-00017 Mixture M-4 Composition Compound Concentration No. Abbreviation /% by weight 1 CY-3-O2 12.0 2 CY-5-O2 10.5 3 CCY-3-O1 6.0 4 CCY-3-O2 7.0 5 CCY-5-O2 5.0 6 CPY-2-O2 12.0 7 CPY-3-O2 12.0 8 PYP-2-3 7.5 9 CC-3-V1 4.0 10 CC-3-V 24.0 100.0 Physical properties T(N, I) 85.0 C. n.sub.e(20 C., 589 nm) = 1.5956 n(20 C., 589 nm) = 0.1120 .sub.(20, 1 kHz) = 7.9 (20, 1 kHz) = 4.2 .sub.1(20 C.) = 145 mPa .Math. s k.sub.11(20 C.) = 14.2 pN k.sub.33(20 C.) = 16.7 pN V.sub.0(20 C.) = 2.08 V

(72) As described in Examples 1 and 2, mixture M-4 is also divided into several parts and its stability to exposure to an LCD backlight and to a UV source is investigated as such and with various added compounds in a test cell with an alignment material for planar alignment and flat ITO electrodes.

Example 5

(73) The following mixture (M-5) is prepared and investigated.

(74) TABLE-US-00018 Mixture M-5 Composition Compound Concentration No. Abbreviation /% by weight 1 B-2O-O5 4.0 2 CY-3-O2 12.0 3 CCH-34 2.5 4 CCP-V-1 1.5 5 CCY-3-O2 10.0 6 CCY-5-O2 2.0 7 CLY-3-O2 8.0 8 CPY-2-O2 6.0 9 CPY-3-O2 10.0 10 PGIY-2-O4 4.0 11 CC-3-V 30.0 12 CC-3-V1 10.0 100.0 Physical properties T(N, I) 87.0 C. n.sub.e(20 C., 589 nm) = 1.5829 n(20 C., 589 nm) = 0.1019 .sub.(20, 1 kHz) = 7.1 (20, 1 kHz) = 3.7 .sub.1(20 C.) = 112 mPa .Math. s k.sub.11(20 C.) = 15.2 pN k.sub.33(20 C.) = 18.0 pN

(75) As described in Examples 1 and 2, mixture M-5 is also divided into several parts and its stability to exposure to an LCD backlight and to a UV source is investigated as such and with various added compounds in a test cell with an alignment material for planar alignment and flat ITO electrodes.