Compounds and liquid-crystalline medium

Abstract

Compounds of the formula I, and liquid-crystalline media, preferably having a nematic phase and negative dielectric anisotropy, comprising a) one or more compounds of the formula I ##STR00001## and one or more 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 formula B ##STR00003## Methods for making and using these liquid-crystalline media in electro-optical displays, particularly in active-matrix displays based on the VA, ECB, PALC, FFS or IPS effect and the displays which contain these media. Methods for stabilizing liquid-crystalline media with compounds of formula I, where the liquid-crystalline media comprise one or more compounds of the formula II and one or more compounds selected from compounds of the formulae III-1 to III-4 and formula B.

Claims

1. A liquid crystalline medium comprising a. one or more compounds of the formulae I-9, I-10 or I-11 ##STR00260##

2. A medium according to claim 1, wherein the total concentration of the one or more compounds of the formulae I-9, I-10 or I-11 in the medium as a whole is from 1 ppm to 2500 ppm.

3. A medium according to claim 1, which further comprises a compound of the formula II ##STR00261## in which R.sup.22 denotes an unsubstituted alkenyl radical having 2 to 7 C atoms and R.sup.21 denotes n-propyl and R.sup.22 denotes vinyl.

4. A 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. A medium according to claim 1, which further comprises one or more compounds of the formula III-4 ##STR00262## 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.

6. A medium according to claim 1, which additionally comprises one or more chiral compounds.

7. A compound of the formulae I-9, I-10 or I-11 ##STR00263##

8. An electro-optical display electro-optical component, which contains a liquid-crystalline medium according to claim 1.

9. A display according to claim 8, which utilize a IPS, FFS, VA or ECB effect.

10. A display according to claim 8, which contains an active-matrix addressing device.

11. A method which comprises including a compound of claim 7 in a liquid-crystalline medium.

12. A method which comprises including a liquid-crystalline medium according to claim 1 in an electro-optical display or in an electro-optical component.

13. A process for the preparation of a liquid-crystalline medium according to claim 1, comprising mixing one or more compounds of the formulae I-9, I-10 or I-11 with one or more compounds of the formula B ##STR00264## 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.

14. A process for the stabilization of a liquid-crystalline medium which comprises adding to said liquid-crystalline medium one or more compounds of claim 7, and optionally one or more compounds of the formulae OH-1 to OH-6, ##STR00265##

15. A process for the preparation of a compound according to claim 7, which comprises hydrogenating the corresponding 2,2,6,6-tetramethylpiperidine 1-oxyl or 1-benzyl precursor.

16. A process for the preparation of a liquid-crystalline medium according to claim 3, comprising mixing one or more compounds of the formulae I-9, I-10 or I-11 with one or more compounds of the formula B ##STR00266## 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 and one or more compounds of the formula II.

17. A process for the preparation of a liquid-crystalline medium according to claim 5, comprising mixing one or more compounds of the Formulae I-9, I-10 or I-11 with one or more compounds of the formula B ##STR00267## 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 and one or more compounds of the formula III-4.

18. A medium according to claim 3, which further comprises a compound of the formula II and one or more compounds of formula B, in which ##STR00268## 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) ##STR00216## ##STR00217## ##STR00218## ##STR00219## ##STR00220##

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

Substance Example 1

(5) ##STR00221##

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

(6) ##STR00222##

(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-tribromo-benzene and 67.70 g (476.0 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-di-isopropoxy-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) ##STR00223##

(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) ##STR00224##

(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 is 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) ##STR00225##

(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, allowed to thaw slowly 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) ##STR00226##

(18) 0.31 g (7.87 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.+].

Step 1.6: Synthesis of bis(2,2,6,6-tetramethylpiperidin-4-yl) 2-{3-[2,5-bis({4-butyl-5-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl})phenyl]propyl}-2-butylpropanedioate 1

(21) ##STR00227##

(22) 1.5 g (0.1 mmol) of hexaradical 1 are dissolved in 20 ml of THF, and 1.5 g of sponge nickel (Johnson-Matthey A-7000) are added. The mixture is stirred at a hydrogen pressure of 5 bar and 50 C. for 17 h. The reaction solution is allowed to cool to RT, filtered and evaporated in vacuo. The crude product obtained is purified by column chromatography on basic aluminium oxide (RediSep Rf) in a CombiFlash apparatus with dichloro-methane/methanol (95:5), and the product fractions are combined and evaporated in vacuo. The product is dried in a bulb-tube apparatus at 50 C. and 3.210.sup.1 mbar for 3 h, giving the product as a foaming, glass-like solid.

(23) Phases: T.sub.g (glass transition temperature) 39 C. C (melting point) 41 C. I (isotropic).

(24) MS (APCI)=1515.1 [M+H].sup.+.

(25) .sup.1H NMR (500 MHz, CDCl.sub.3)

(26) =0.54-0.99 (m.sub.(superimposed), 16H, 6 NH, CH.sub.2), 1.09-1.40 (m.sub.(superimposed) 97H, CH.sub.3, CH.sub.2), 1.48 (m.sub.c, 6H, CH.sub.2), 1.82-2.02 (m.sub.(superimposed), 24H, CH.sub.2), 2.57 (t, J=7.63 Hz, 6H), 5.24 (m.sub.c, 6H, CH(CH.sub.2).sub.2), 6.93 (d.sub.(superimposed with singlet), J=7.87 Hz, 2H), 7.04 (d, J=7.72 Hz, 1H).

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

(27) ##STR00228##

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

(28) ##STR00229##

(29) 3.20 g (80.01 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

(30) ##STR00230##

(31) 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

(32) ##STR00231##

(33) 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.

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

(35) MS (APCI)=1734.

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

Substance/Synthesis Example 2

(37) ##STR00232##

Substance/Synthesis Example 2

(38) ##STR00233##

Substance/Synthesis Example 3

(39) ##STR00234##

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

Substance/Synthesis Example 3

(41) ##STR00235##

(42) Substance/Synthesis Example 4:

(43) ##STR00236##

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

Substance/Synthesis Example 4

(45) ##STR00237##

Substance/Synthesis Example 5

(46) ##STR00238##

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

Substance/Synthesis Example 5

(48) ##STR00239##

Substance/Synthesis Example 6

(49) ##STR00240##

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

Substance/Synthesis Example 6

(51) ##STR00241##

Substance/Synthesis Example 7

(52) ##STR00242##

Substance/Synthesis Example 7

(53) ##STR00243##

(54) Phases: (glass transition temperature) 14 C. I (isotropic).

Substance/Synthesis Example 8

(55) ##STR00244##

Substance/Synthesis Example 8

(56) ##STR00245##

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

Substance/Synthesis Example 9

(58) ##STR00246##

Substance/Synthesis Example 9

(59) ##STR00247##

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

Substance/Synthesis Example 10: Synthesis of 4-(3-{3-[3,5-bis({3-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]propoxy})phenyl]-5-{3-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]propoxy}phenoxy}propoxy)-2,2,6,6-tetramethylpiperidine

(61) ##STR00248##

Step 8.1: Synthesis of 1-benzyl-2,2,6,6-tetramethylpiperidin-4-ol A

(62) ##STR00249##

(63) 37.80 ml (318.2 mmol) of benzyl bromide and 100.0 g (635.9 mmol) of 2,2,6,6-tetramethylpiperidin-4-ol are dissolved in 500 ml of N,N-dimethylformamide (DMF), and the mixture is stirred at 120 C. for 18 hours (h). The reaction solution is cooled to room temperature (RT) and stirred into a mixture of water and ice. The mixture is stirred for 30 min., and the precipitated solid is filtered off with suction and extracted with methyl tertiary-butyl ether (MTB ether). The product solution is washed a number of times with saturated sodium chloride solution, and the organic phase is dried over sodium sulfate, filtered and evaporated in vacuo. The crystalline crude product obtained is recrystallised from heptane/isopropanol (5:1) at 5 C., and the crystals are filtered off with suction and dried in vacuo at 40 C. for 18 h, giving the reaction product as a colourless, crystalline solid.

Step 8.2: Synthesis of 1-benzyl-2,2,6,6-tetramethyl-4-[3-(oxan-2-yloxy)-propoxy]piperidine B

(64) ##STR00250##

(65) 35.00 g (141.5 mmol) of tetramethylpiperidine A, 47.20 g (211.5 mmol) of 2-(3-bromopropoxytetrahydropyran) and 20.00 g (62.04 mmol) of tetra-n-butylammonium bromide are suspended in 270 ml of toluene, and 110 ml (2.10 mol) of sodium hydroxide solution (50%) are rapidly added drop wise at room temperature (RT). The reaction mixture is stirred at 60 C. for 16 hours (h) and subsequently allowed to cool to RT. The reaction mixture is carefully added to a mixture of ice-water and toluene, and the phases are separated. The aqueous phase is extracted with toluene, and the combined organic phases are washed with saturated sodium chloride solution, dried over sodium sulfate, filtered and evaporated in vacuo, giving a yellow, partially crystalline crude product, to which 300 ml of heptane are added, and the mixture is stirred and filtered. The reaction product is obtained in the mother liquor as a yellow oil, which is filtered through silica gel with toluene/ethyl acetate (9:1 to 3:1). The product fractions are combined and evaporated in vacuo, giving the product as a slightly yellow oil.

Step 8.3: Synthesis of 3-[(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]propan-1-ol C

(66) ##STR00251##

(67) 34.60 g (80.91 mmol) of B and 20.00 g (116.1 mmol) of toluene-4-sulfonic acid monohydrate are dissolved in 700 ml of methanol, and 100 ml of water are added at RT (exothermic/7 K). The reaction solution is stirred at 40 C. for 1 h, subsequently evaporated in vacuo and diluted with methyl tert-butyl ether (MTBE). The mixture is carefully washed with saturated NaHCO.sub.3 solution, and the phases are separated. The organic phase is washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated in vacuo, giving the crude product as a yellow oil, which is filtered through silica gel with dichloromethane (DCM) and MTBE (3:1). The product fractions are combined, giving the reaction product as a virtually colourless oil.

Step 8.4: Synthesis of 1-benzyl-4-[3-(3-{3-[(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]propoxy}-5-bromophenoxy)propoxy]-2,2,6,6-tetramethylpiperidine D

(68) ##STR00252##

(69) 5.80 g (30.7 mmol) of 5-bromobenzene-1,3-diol, 21.50 g (70.4 mmol) of alcohol C from the preceding step and 18.51 g (70.58 mmol) of triphenylphosphine are dissolved in 120 ml of tetrahydrofuran (THF) and cooled to 0 C. 14.70 ml (70.58 mmol) of diisopropyl azodicarboxylate are added dropwise to the reaction solution, and the mixture is stirred at RT for 16 h. The reaction mixture is evaporated in vacuo, 200 ml of heptane are added, and the mixture is stirred vigorously. The precipitated triphenylphosphine oxide is filtered off, and the mother liquor is washed with 100 ml of heptane and evaporated in vacuo. The crude product obtained is filtered through silica gel with heptane/MTBE (7:3), and the combined product fractions are evaporated in vacuo, giving the reaction product as a viscous oil.

Step 8.5: Synthesis of 1-benzyl-4-[3-(3-{3-[(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]propoxy}-5-[3,5-bis({3-[(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]propoxy})-phenyl]phenoxy)propoxy]-2,2,6,6-tetramethylpiperidine E

(70) ##STR00253##

(71) 14.60 g (19.11 mmol) of the bromide D from the preceding step, 2.54 g (10.0 mmol) of bis(pinacolato)diboron and 2.81 g (28.7 mmol) of potassium acetate are initially introduced in 150 ml of dioxane and degassed under an argon atmosphere for 30 min. 220.00 mg (0.30 mmol) of PdCl.sub.2-dppf are added, and the reaction mixture is stirred at 100 C. for 1 h. It is then cooled to below the boiling point, a further 220.00 mg (0.30 mmol) of PdCl.sub.2-dppf and 25 ml (50 mmol) of sodium carbonate solution (2 M) are added, and the mixture is stirred at 100 C. for 20 h. The reaction mixture is allowed to cool to RT, water and MTBE are added, and the phases are separated. The water phase is extracted with MTBE, and the organic phases are combined, washed with water, dried over sodium sulfate, filtered and evaporated in vacuo. The crude product is obtained as a black oil and is filtered through silica gel with heptane/MTBE (8:2 to 7:3). The combined product fractions are evaporated in vacuo, giving the reaction product as a yellow resin.

(72) MS (APCI)=1367.9 [M].sup.+

(73) .sup.1H NMR (500 MHz, CDCl.sub.3)

(74) =0.99 (s, 24H, CH.sub.3), 1.13 (s, 24H, CH.sub.3), 1.45 (t, J=11.7 Hz, 8H, CH.sub.2), 1.94 (dd, J=12.25, 3.84 Hz, 4H, CH.sub.2), 2.09 (quint, J=6.16 Hz, 4H, CH.sub.2), 3.71 (t.sub.(superimposed with multiplet), J=6.21 Hz, 6H, CH.sub.2, CH), 3.83 (s, 8H, CH.sub.2), 4.15 (t, 6.15 Hz), 6.53 (t, 2.06 Hz, 2H), 6.76 (d, J=2.12 Hz, 4H), 7.16 (t, 7.26 Hz, 4H), 7.28 (t, 7.72 Hz, 8H), 7.43 (d, J=7.49 Hz, 8H).

Step 8.6: Synthesis of 4-(3-{3-[3.5-bis({3-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]propoxy})phenyl]-5-{3-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]-propoxy}phenoxy}propoxy)-2,2,6,6-tetramethylpiperidine 10

(75) ##STR00254##

(76) 8.50 g (6.21 mmol) of the product E from the preceding step are dissolved in 107 ml of tetrahydrofuran, 3.00 g of 5% Pd/C (50% of water, Degussa) are added, and the mixture is stirred under a hydrogen atmosphere at atmospheric pressure and room temperature (RT) for 17 h. The reaction mixture is filtered and evaporated in vacuo. The residue is taken up in 100 ml of MTBE, 50 ml of 2 N hydrochloric acid are added, and the phases are separated. The aqueous phase is extracted with MTBE, and the aqueous phase is then adjusted to pH 12-13 using 32% sodium hydroxide solution and extracted with MTBE ether. The combined organic phases are washed with saturated sodium chloride solution, dried over sodium sulfate, filtered and evaporated in vacuo. The crude product obtained is filtered through Al.sub.2O.sub.3 (basic aluminium oxide) with dichloromethane/methanol, and the product fractions are combined and evaporated in vacuo, giving the product as a slightly yellow oil, which solidifies.

(77) Phases: T.sub.g (glass transition temperature) 4 C., T(C,I) (melting point) 64 C. I (isotropic).

(78) MS (APCI)=1007.7 [M+H].sup.+

(79) .sup.1H NMR (500 MHz, CDCl.sub.3)

(80) =0.62 (s.sub.(broad), 4H, NH), 1.02 (t, J=11.76, 8H), 1.15 (s, 24H, CH.sub.3), 1.19 (s, 24H, CH.sub.3), 1.98 (dd, 12.49, 3.9 Hz 8H), 2.07 (quint., 6.13 Hz, 8H), 3.69 (t.sub.(superimposed), J=5.8 Hz, 12H), 4.12 (t, J=6.1 Hz, 8H), 6.50 (s.sub.(broad)=2H), 6.73 (d, J=2.1 Hz, 4H).

Substance/Synthesis Example 11: Synthesis of

(81) ##STR00255##

(82) The compound is prepared analogously, giving a colourless oil.

(83) Phases: T.sub.g (glass transition temperature) 118 C.

(84) .sup.1H NMR (500 MHz, CDCl.sub.3)

(85) =6.35 (dd, J=13.3, 2.2 Hz, 6H), 4.05 (t, J=6.1 Hz, 8H), 3.81-3.51 (m, 12), 2.57-2.48 (m, 4H), 2.04 (p, J=6.2 Hz, 8H), 1.98 (dd, J=12.5, 3.9 Hz, 8H), 1.67-1.56 (m, 4H), 1.36 (d, J=4.1 Hz, 6H), 1.18 (d J=19.7 Hz, 48H), 1.02 (t, J=11.7 Hz, 8H), 0.69 (s, 4H).

Mixture Examples

(86) 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 1.1.1 to 1.3.3 and Corresponding Comparative Examples

(87) The following mixture (M-1) is prepared and investigated.

(88) TABLE-US-00008 Mixture M-1 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 Note: Here, as throughout the present application, t.b.d. means to be determined, unless indicated otherwise.

(89) Mixture M-1 is divided into several parts and investigated as described below.

(90) Firstly, the stability of the voltage holding ratio of mixture (M-1) itself is determined. The stability of mixture M-1 to UV exposure is investigated in a test cell having an alignment material for planar alignment (polyimide AL-16301 from Japan Synthetic Rubber), with a layer thickness of 6.5 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 determined in each case after 5 minutes at a temperature of 100 C. The addressing frequency (or measurement frequency) here is 60 Hz, unless specifically indicated otherwise. The results are compiled in Table 1a. Here, as below, six test cells are filled and investigated for each individual mixture. The values indicated are the mean of the six individual values.

(91) 100 ppm, 500 ppm and 1000 ppm of the reference compound (called R-1 here)

(92) ##STR00256##

(93) are then added to each of 3 further parts of mixture M-1, and the stability of the resultant mixtures (C-1-1.1, C-1-1.2 and C-1-1.3) is investigated as described above. The results are shown in the following table, Table 1a.

(94) Next, 100 ppm, 500 ppm and 1000 ppm of in each case one of the compounds I-1 to I-3

(95) ##STR00257##

(96) are added to sets of in each case three corresponding, remaining parts of mixture M-1, and the stability of the resultant mixtures (M-1-1.1 to M-1-1.3, M-2-2.1 to M-1-2.3 and M-1-3.1 to M-1-3.3) is investigated as described above. The results are shown in the following table, Table 1a.

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

(98) TABLE-US-00009 TABLE 1a VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 None 0 69 52 C1.1 C-1-1.1 R-1 100 76.5 70.0 C1.2 C-1-1.2 R-1 500 81.0 75.5 C1.3 C-1-1.3 R-1 1000 79.5 74.8 M1.1.1 M-1-1.1 I-1 100 86.4 78.8 M1.1.2 M-1-1.2 I-1 500 90.6 86.0 M1.1.3 M-1-1.3 I-1 1000 90.7 86.9 M1.2.1 M-1-2.1 I-2 100 84.5 76.2 M1.2.2 M-1-2.2 I-2 500 87.7 82.4 M1.2.3 M-1-2.3 I-2 1000 86.5 80.4 M1.3.1 M-1-3.1 I-3 100 81.7 74.5 M1.3.2 M-1-3.2 I-3 500 89.5 86.6 M1.3.3 M-1-3.3 I-3 1000 87.8 85.5

(99) It is readily evident here that compounds I-1 to I-3 exhibit clearly stabilising properties, even in relatively low concentrations.

(100) The investigations described above are repeated at an addressing/measurement frequency of 10 Hz. The results are compiled in the following table, Table 1 b.

(101) TABLE-US-00010 TABLE 1b VHR(t)/% @ c(stab.)/ 100 C., 10 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 None 0 44 26 C1.1 C-1-1.1 R-1 100 60.2 50.4 C1.2 C-1-1.2 R-1 500 59.3 53.0 C1.3 C-1-1.3 R-1 1000 50.9 50.4 M1.1.1 M-1-1.1 I-1 100 66.9 54.5 M1.1.2 M-1-1.2 I-1 500 79.6 71.9 M1.1.3 M-1-1.3 I-1 1000 77.7 72.5 M1.2.1 M-1-2.1 I-2 100 t.b.d. t.b.d. M1.2.2 M-1-2.2 I-2 500 t.b.d. t.b.d. M1.2.3 M-1-2.3 I-2 1000 t.b.d. t.b.d. M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(102) The investigations described above are repeated at an addressing/measurement frequency of 3 Hz. The results are compiled in the following table, Table 1c.

(103) TABLE-US-00011 TABLE 1c VHR(t)/% @ c(stab.)/ 100 C., 3 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 None 0 28 19 C1.1 C-1-1.1 R-1 100 38.7 34.0 C1.2 C-1-1.2 R-1 500 36.6 34.3 C1.3 C-1-1.3 R-1 1000 30.7 31.8 M1.1.1 M-1-1.1 I-1 100 45.7 37.7 M1.1.2 M-1-1.2 I-1 500 59.9 53.9 M1.1.3 M-1-1.3 I-1 1000 60.5 52.8 M1.2.1 M-1-2.1 I-2 100 t.b.d. t.b.d. M1.2.2 M-1-2.2 I-2 500 t.b.d. t.b.d. M1.2.3 M-1-2.3 I-2 1000 t.b.d. t.b.d. M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(104) The investigations are additionally repeated at a lower temperature, here at a temperature of 60 C. Addressing voltages/measurement frequencies of 3 Hz and 1 Hz are used here. The results are compiled in the two following tables, Table 1 d and Table 1e.

(105) TABLE-US-00012 TABLE 1d VHR(t)/% @ c(stab.)/ 60 C., 3 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 None 0 66.3 45.8 C1.1 C-1-1.1 R-1 100 87.0 76.3 C1.2 C-1-1.2 R-1 500 86.2 78.4 C1.3 C-1-1.3 R-1 1000 85.0 78.7 M1.1.1 M-1-1.1 I-1 100 90.8 82.9 M1.1.2 M-1-1.2 I-1 500 93.8 89.6 M1.1.3 M-1-1.3 I-1 1000 92.3 88.7 M1.2.1 M-1-2.1 I-2 100 t.b.d. t.b.d. M1.2.2 M-1-2.2 I-2 500 t.b.d. t.b.d. M1.2.3 M-1-2.3 I-2 1000 t.b.d. t.b.d. M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(106) TABLE-US-00013 TABLE 1e VHR(t)/% @ c(stab.)/ 60 C., 1 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-1 None 0 45.3 33.8 C1.1 C-1-1.1 R-1 100 72.6 63.3 C1.2 C-1-1.2 R-1 500 70.2 64.3 C1.3 C-1-1.3 R-1 1000 65.8 63.3 M1.1.1 M-1-1.1 I-1 100 81.3 74.1 M1.1.2 M-1-1.2 I-1 500 86.6 82.3 M1.1.3 M-1-1.3 I-1 1000 83.3 80.6 M1.2.1 M-1-2.1 I-2 100 t.b.d. t.b.d. M1.2.2 M-1-2.2 I-2 500 t.b.d. t.b.d. M1.2.3 M-1-2.3 I-2 1000 t.b.d. t.b.d. M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(107) In addition, the mixtures are subjected to a test for exposure to a backlight. To this end, the stability of corresponding test cells having an alignment layer for planar alignment (PI: AL16301, as described above) and flat ITO electrodes to illumination with a cold cathode (CCFL) LCD backlight is investigated. To this end, corresponding test cells are filled and sealed. These cells are then exposed to illumination with a commercial LED backlight for LCDs for various times (48 h, 336 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 tables, Tables 2a to 2c.

(108) TABLE-US-00014 TABLE 2a VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 48 h (Ref.) M-1 None 0 72.4 61.2 C1.1 C-1-1.1 R-1 100 85.7 82.3 C1.2 C-1-1.2 R-1 500 84.2 84.3 C1.3 C-1-1.3 R-1 1000 83.7 84.5 M1.1.1 M-1-1.1 I-1 100 90.5 89.7 M1.1.2 M-1-1.2 I-1 500 93.7 92.9 M1.1.3 M-1-1.3 I-1 1000 92.2 93.0 M1.2.1 M-1-2.1 I-2 100 87.2 84.5 M1.2.2 M-1-2.2 I-2 500 88.9 89.6 M1.2.3 M-1-2.3 I-2 1000 89.4 89.2 M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(109) TABLE-US-00015 TABLE 2b VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 336 h (Ref.) M-1 None 0 72.4 53.9 C1.1 C-1-1.1 R-1 100 85.7 72.6 C1.2 C-1-1.2 R-1 500 84.2 79.7 C1.3 C-1-1.3 R-1 1000 83.7 79.3 M1.1.1 M-1-1.1 I-1 100 90.5 82.4 M1.1.2 M-1-1.2 I-1 500 93.7 89.2 M1.1.3 M-1-1.3 I-1 1000 92.2 90.5 M1.2.1 M-1-2.1 I-2 100 87.2 80.9 M1.2.2 M-1-2.2 I-2 500 88.9 86.2 M1.2.3 M-1-2.3 I-2 1000 89.4 86.6 M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(110) TABLE-US-00016 TABLE 2c VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 1000 h (Ref.) M-1 None 0 72.4 53.6 C1.1 C-1-1.1 R-1 100 85.7 69.6 C1.2 C-1-1.2 R-1 500 84.2 78.0 C1.3 C-1-1.3 R-1 1000 83.7 77.0 M1.1.1 M-1-1.1 I-1 100 90.5 77.4 M1.1.2 M-1-1.2 I-1 500 93.7 85.4 M1.1.3 M-1-1.3 I-1 1000 92.2 87.5 M1.2.1 M-1-2.1 I-2 100 87.2 76.6 M1.2.2 M-1-2.2 I-2 500 88.9 83.4 M1.2.3 M-1-2.3 I-2 1000 89.4 85.0 M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(111) In addition, the ion densities are determined for the mixtures. The results are compiled in the following table, Table 3.

(112) The exposure is carried out in a commercial UV/Suntest instrument from Hereaus, Hanau. The irradiation is carried out using a Hoya lamp with a cut-off filter with a wavelength of 340 nm (i.e. T=50% at 340 nm). The spectral distribution of the radiation from this lamp is similar to the spectral distribution of natural sunlight. The irradiation intensity is 3 J/cm.sup.2, measured using an appropriate detector at a wavelength of 365 nm. The irradiation is carried out at an ambient temperature of typically 20 C. for about hour.

(113) The ion density (ID for short) is determined in closed test cells. The test cells have, as described above, an alignment layer of the polyimide AL-16301. However, they have a layer thickness of 6.0 m. The measurements are carried out at 3 V, 0.03 Hz and 60 C.

(114) TABLE-US-00017 TABLE 3 Ion density/pC c(stab.)/ t = 30 min, Ex. Mixture Stabiliser ppm t = 0 h Suntest (Ref.) M-1 None 0 605 1519 C1.1 C-1-1.1 R-1 100 238 458 C1.2 C-1-1.2 R-1 500 261 438 C1.3 C-1-1.3 R-1 1000 357 500 M1.1.1 M-1-1.1 I-1 100 175 376 M1.1.2 M-1-1.2 I-1 500 117 216 M1.1.3 M-1-1.3 I-1 1000 106 205 M1.2.1 M-1-2.1 I-2 100 t.b.d. t.b.d. M1.2.2 M-1-2.2 I-2 500 t.b.d. t.b.d. M1.2.3 M-1-2.3 I-2 1000 t.b.d. t.b.d. M1.3.1 M-1-3.1 I-3 100 t.b.d. t.b.d. M1.3.2 M-1-3.2 I-3 500 t.b.d. t.b.d. M1.3.3 M-1-3.3 I-3 1000 t.b.d. t.b.d.

(115) It is readily evident here that compound I-1, even in relatively low concentrations, exhibits clearly stabilising properties which are clearly superior both to those of the starting mixture and also to those of the comparative mixture. In addition, the ion density is very greatly reduced compared with the undoped mixture.

(116) The compounds of the formulae I-1 to I-3 have a stabilising activity which is superior to the comparative compound R-1 in all concentrations employed. This leads, inter alia, to a reduction in the risk of image sticking on exposure to the backlight.

Examples 2.1.1 to 2.3.3 and Corresponding Comparative Examples

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

(118) TABLE-US-00018 Mixture M-2 Composition Compound Concentration No. Abbreviation /% by weight 1 CC-3-V 32.0 2 CC-3-V1 11.0 3 CC-3-2V1 4.5 4 PP-1-2V1 2.0 5 CCP-3-OT 7.5 6 CCP-5-OT 1.5 7 DPGU-4-F 5.0 8 PUQU-3-F 1.5 9 APUQU-2-F 7.0 10 APUQU-3-F 7.0 11 PGUQU-3-F 3.0 12 PGUQU-4-F 8.0 13 PGUQU-5-F 2.0 14 DGUQU-4-F 8.0 100.0 Physical properties T(N, I) = 85.0 C. n.sub.e(20 C., 589 nm) = 1.5865 n(20 C., 589 nm) = 0.1089 .sub.(20, 1 kHz) = 19.0 (20, 1 kHz) = 15.3 .sub.1(20 C.) = 89 mPa .Math. s k.sub.11(20 C.) = 14.4 pN k.sub.33(20 C.) = 15.1 pN V.sub.0(20 C.) = t.b.d. V V.sub.10(20 C.) = t.b.d. V Note: t.b.d.: to be determined.

(119) The corresponding compounds are added to mixture M-2, divided into several parts are described in Example 1 in the case of mixture M-1, and investigated as described therein. The results are compiled in the following tables.

(120) TABLE-US-00019 TABLE 4a VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) C1 None 0 96.3 77.6 C2.1 C-2-1.1 R-1 100 98.6 90.1 C2.2 C-2-1.2 R-1 500 98.5 85.4 C2.3 C-2-1.3 R-1 1000 98.3 85.1 M2.1.1 M-2-1.1 I-1 100 99.0 91.8 M2.1.2 M-2-1.2 I-1 500 99.2 91.5 M2.1.3 M-2-1.3 I-1 1000 99.0 89.7 M2.2.1 M-2-2.1 I-2 100 98.7 89.7 M2.2.2 M-2-2.2 I-2 500 98.6 81.3 M2.2.3 M-2-2.3 I-2 1000 98.4 74.4 M2.3.1 M-2-3.1 I-3 100 97.1 90.5 M2.3.2 M-2-3.2 I-3 500 98.0 88.4 M2.3.3 M-2-3.3 I-3 1000 97.6 86.9 M2.4.1 M-2-4.1 I-4 100 97.3 84.4 M2.4.2 M-2-4.2 I-4 500 98.7 79.8 M2.4.3 M-2-4.3 I-4 1000 98.8 72.7

(121) It is readily evident here that compounds I-1 to I-4 and in particular I-1 to I-3 have clearly stabilising properties, even in relatively low concentrations.

(122) Compound I-1 has an excellent stabilising activity in a concentration of 100 ppm. This leads to a reduction in the risk of image sticking on exposure to the backlight.

(123) The investigations described above are repeated at an addressing/measurement frequency of 10 Hz. The results are compiled in the following table, Table 4b.

(124) TABLE-US-00020 TABLE 4b VHR(t)/% @ c(stab.)/ 100 C., 10 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-2 None 0 96.4 56.3 C2.1 C-2-1.1 R-1 100 t.b.d. t.b.d. C2.2 C-2-1.2 R-1 500 t.b.d. t.b.d. C2.3 C-2-1.3 R-1 1000 97.7 58.5 M2.1.1 M-2-1.1 I-1 100 t.b.d. t.b.d. M2.1.2 M-2-1.2 I-1 500 t.b.d. t.b.d. M2.1.3 M-2-1.3 I-1 1000 98.7 71.0 M2.2.1 M-2-2.1 I-2 100 t.b.d. t.b.d. M2.2.2 M-2-2.2 I-2 500 t.b.d. t.b.d. M2.2.3 M-2-2.3 I-2 1000 t.b.d. t.b.d. M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(125) The investigations described above are repeated at an addressing/measurement frequency of 3 Hz. The results are compiled in the following table, Table 4c.

(126) TABLE-US-00021 TABLE 4c VHR(t)/% @ c(stab.)/ 100 C., 3 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-2 None 0 96.4 43.3 C2.1 C-2-1.1 R-1 100 t.b.d. t.b.d. C2.2 C-2-1.2 R-1 500 t.b.d. t.b.d. C2.3 C-2-1.3 R-1 1000 97.7 39.0 M2.1.1 M-2-1.1 I-1 100 t.b.d. t.b.d. M2.1.2 M-2-1.2 I-1 500 t.b.d. t.b.d. M2.1.3 M-2-1.3 I-1 1000 98.7 51.8 M2.2.1 M-2-2.1 I-2 100 t.b.d. t.b.d. M2.2.2 M-2-2.2 I-2 500 t.b.d. t.b.d. M2.2.3 M-2-2.3 I-2 1000 t.b.d. t.b.d. M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(127) The investigations are additionally repeated at a temperature of 60 C. Addressing voltages/measurement frequencies of 3 Hz and 1 Hz are used here. The results are compiled in the two following tables, Table 4d and Table 4e.

(128) In addition, the mixtures are subjected to a test for exposure to a backlight. To this end, the stability of corresponding test cells having an alignment layer for planar alignment (PI: AL16301, as described above) and flat ITO electrodes to illumination with a cold cathode (CCFL) LCD backlight is investigated. To this end, corresponding test cells are exposed to the illumination for various times (48 h, 336 h and 1000 h). The voltage holding ratio is then in each case determined after 5 minutes at the temperature of 100 C. The results are compiled in the following tables, Tables 5a to 5c.

(129) TABLE-US-00022 TABLE 5a VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 48 h (Ref.) M-2 None 0 95.4 79.6 C2.1 C-2-1.1 R-1 100 98.1 95.7 C2.2 C-2-1.2 R-1 500 97.7 96.3 C2.3 C-2-1.3 R-1 1000 97.7 96.6 M2.1.1 M-2-1.1 I-1 100 98.6 97.7 M2.1.2 M-2-1.2 I-1 500 98.8 98.2 M2.1.3 M-2-1.3 I-1 1000 98.8 98.0 M2.2.1 M-2-2.1 I-2 100 98.2 97.2 M2.2.2 M-2-2.2 I-2 500 98.2 96.7 M2.2.3 M-2-2.3 I-2 1000 97.8 96.2 M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(130) TABLE-US-00023 TABLE 5b VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 336 h (Ref.) M-2 None 0 95.4 63.5 C2.1 C-2-1.1 R-1 100 98.1 85.8 C2.2 C-2-1.2 R-1 500 97.7 88.4 C2.3 C-2-1.3 R-1 1000 97.7 90.5 M2.1.1 M-2-1.1 I-1 100 98.6 92.0 M2.1.2 M-2-1.2 I-1 500 98.8 94.9 M2.1.3 M-2-1.3 I-1 1000 98.8 94.7 M2.2.1 M-2-2.1 I-2 100 98.2 90.9 M2.2.2 M-2-2.2 I-2 500 98.2 90.5 M2.2.3 M-2-2.3 I-2 1000 97.8 89.6 M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(131) TABLE-US-00024 TABLE 5c VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 1000 h (Ref.) M-2 None 0 95.4 58.6 C2.1 C-2-1.1 R-1 100 98.1 73.9 C2.2 C-2-1.2 R-1 500 97.7 77.3 C2.3 C-2-1.3 R-1 1000 97.7 83.3 M2.1.1 M-2-1.1 I-1 100 98.6 83.8 M2.1.2 M-2-1.2 I-1 500 98.8 88.5 M2.1.3 M-2-1.3 I-1 1000 98.8 89.1 M2.2.1 M-2-2.1 I-2 100 98.2 80.1 M2.2.2 M-2-2.2 I-2 500 98.2 83.3 M2.2.3 M-2-2.3 I-2 1000 97.8 84.4 M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(132) As can be seen from Table 5, even a low concentration of compounds I-1 and I-2 leads to a considerable improvement in the final value of the VHR after exposure to light from an LCD backlight.

(133) In addition, the ion densities are determined for the mixtures. The results are compiled in the following table, Table 6.

(134) TABLE-US-00025 TABLE 6 Ion density/pC c(stab.)/ t = 30 min, Ex. Mixture Stabiliser ppm t = 0 h Suntest (Ref.) M-2 None 0 152 681 C2.1 C-2-1.1 R-1 100 57 275 C2.2 C-2-1.2 R-1 500 40 449 C2.3 C-2-1.3 R-1 1000 43 579 M2.1.1 M-2-1.1 I-1 100 37 193 M2.1.2 M-2-1.2 I-1 500 21 217 M2.1.3 M-2-1.3 I-1 1000 23 254 M2.2.1 M-2-2.1 I-2 100 37 233 M2.2.2 M-2-2.2 I-2 500 39 433 M2.2.3 M-2-2.3 I-2 1000 43 634 M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(135) It is readily evident here that the compound of the formula I-1, even in relatively low concentrations, exhibits clearly stabilising properties which are clearly superior both to those of the starting mixture and also to those of the comparative mixture. In addition, the ion density is very greatly reduced compared with the undoped mixture.

(136) In addition, the VHR values are determined for the mixtures after heating in test cells for 120 hours. The closed test cells are stored here in an oven at a temperature of 100 C. for the times indicated.

(137) The results are compiled in the following table, Table 7.

(138) TABLE-US-00026 TABLE 7 VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 120 h (Ref.) M-2 None 0 96.3 91.1 C2.1 C-2-1.1 R-1 100 97.7 90.2 C2.2 C-2-1.2 R-1 500 98.5 94.0 C2.3 C-2-1.3 R-1 1000 97.8 84.9 M2.1.1 M-2-1.1 I-1 100 98.7 93.1 M2.1.2 M-2-1.2 I-1 500 99.1 94.0 M2.1.3 M-2-1.3 I-1 1000 99.1 92.9 M2.2.1 M-2-2.1 I-2 100 t.b.d. t.b.d. M2.2.2 M-2-2.2 I-2 500 t.b.d. t.b.d. M2.2.3 M-2-2.3 I-2 1000 t.b.d. t.b.d. M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

(139) In addition, the ion densities are determined for the mixtures. The results are compiled in the following table, Table 8.

(140) The exposure is carried out, as described above, in a commercial UV/Suntest instrument from Hereaus, Hanau. The irradiation is carried out using a Hoya lamp with a cut-off filter with a wavelength of 340 nm (i.e. T=50% at 340 nm). The spectral distribution of the radiation from this lamp is similar to the spectral distribution of natural sunlight. The irradiation intensity is 3 J/cm.sup.2, measured using an appropriate detector at a wavelength of 365 nm. The irradiation is carried out at an ambient temperature of typically 20 C. for about hour.

(141) The ion density (ID for short) is determined in closed test cells. The test cells have, like those described above, an alignment layer of the polyimide AL-16301. However, they have a layer thickness of 5.5 m. The measurements are carried out at 3 V, 0.03 Hz and 60 C.

(142) TABLE-US-00027 TABLE 8 Ion density/pC c(stab.)/ t = 30 min, Ex. Mixture Stabiliser ppm t = 0 h Suntest (Ref.) M-2 None 0 152 681 C2.1 C-2-1.1 R-1 100 57 275 C2.2 C-2-1.2 R-1 500 40 449 C2.3 C-2-1.3 R-1 1000 43 579 M2.1.1 M-2-1.1 I-1 100 37 193 M2.1.2 M-2-1.2 I-1 500 21 217 M2.1.3 M-2-1.3 I-1 1000 23 254 M2.2.1 M-2-2.1 I-2 100 37 233 M2.2.2 M-2-2.2 I-2 500 39 433 M2.2.3 M-2-2.3 I-2 1000 43 634 M2.3.1 M-2-3.1 I-3 100 t.b.d. t.b.d. M2.3.2 M-2-3.2 I-3 500 t.b.d. t.b.d. M2.3.3 M-2-3.3 I-3 1000 t.b.d. t.b.d. M2.4.1 M-2-3.1 I-4 100 t.b.d. t.b.d. M2.4.2 M-2-3.2 I-4 500 t.b.d. t.b.d. M2.4.3 M-2-3.3 I-4 1000 t.b.d. t.b.d.

Examples 3.1.1 to 3.3.3

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

(144) TABLE-US-00028 Mixture M-3 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

(145) Mixture M-3 is divided into several parts and investigated as described in the case of Example 1.

(146) Firstly, the stability of the voltage holding ratio of mixture (M-3) itself is determined. The stability of mixture M-3 to UV exposure is investigated in a test cell having an alignment material for planar alignment and flat ITO electrodes. To this end, corresponding test cells are irradiated in the Suntest for 30 min. The voltage holding ratio is then determined in each case after 5 minutes at a temperature of 100 C. The results are compiled below, in Table 9. Here, as below, six test cells are filled and investigated for each individual mixture. The values indicated are the mean of the six individual values.

(147) Next, 300 ppm of compound R-1 (C-3-1) are added to the remaining three parts of mixture M-3, and 100 ppm, 300 ppm and 600 ppm concentrations of compounds I-1 to I-3 are in each case added to further sets of in each case three parts of mixture M-3, and the stability of the resultant mixtures (C-3-1 and M-3-1.1 to M-3-3.3) is investigated as described above. The results are shown in Table 9 below.

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

(149) TABLE-US-00029 TABLE 9 VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-3 None 0 60.6 1.2 57.1 0.9 C3.1 C-3-1 R-1 300 70.3 1.1 72.7 0.8 M3.1.1 M-3-1.1 I-1 100 88.2 1.2 83.0 0.7 M3.1.2 M-3-1.2 I-1 300 90.7 1.4 86.5 0.8 M3.1.3 M-3-1.3 I-1 600 90.0 0.6 88.5 0.4 M3.2.1 M-3-2.1 I-2 100 85.6 1.6 79.9 1.6 M3.2.2 M-3-2.2 I-2 300 82.6 0.7 81.4 0.9 M3.2.3 M-3-2.3 I-2 600 81.8 1.0 79.7 0.9 M3.3.1 M-3-3.1 I-3 100 79.9 1.2 75.2 1.2 M3.3.2 M-3-3.2 I-3 300 86.2 2.0 84.1 1.3 M3.3.3 M-3-3.3 I-3 600 84.3 2.1 85.9 1.5

Examples 4.1.1 to 4.2.2

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

(151) TABLE-US-00030 Mixture M-4 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.33(20 C.) = 16.7 pN V.sub.0(20 C.) = 2.08 V

(152) Mixture M-4 is divided into several parts. Firstly, the stability of the voltage holding ratio of mixture (M-4) itself is determined. The stability of mixture M-4 to exposure to an LCD backlight is investigated as described above in a test cell having an alignment material for planar alignment and flat ITO electrodes. To this end, corresponding test cells are irradiated with an LCD backlight for 30 min. The voltage holding ratio is then in each case determined after 5 minutes at a temperature of 100 C. The results are compiled below, in Table 10. Here, as below, six test cells are filled and investigated for each individual mixture. The values indicated are the mean of the six individual values.

(153) 500 ppm of compound R-1 are then added to one part of mixture M-4 (mixture C-4-1) and 500 ppm or 1000 ppm of compound I-2 or 500 ppm of compound I-3 are added to each of three further parts of mixture M-4, and the stability of all mixtures to exposure to the LCD backlight is investigated analogously to the procedure described in Examples 1 to 3 in test cells, here with alignment layer SE5811 from Nissan Chemicals, Japan. The results of the VHR measurements after irradiation for 500 hours are compiled in Table 10.

(154) TABLE-US-00031 TABLE 10 VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 500 h (Ref.) M-4 None 0 65.7 2.5 51.8 3.0 C4.1 C-4-1 R-1 500 58.9 2.0 62.0 2.0 M4.1.1 M-4-1.1 I-1 500 70.6 3.0 74.6 1.9 M4.1.2 M-4-1.2 I-1 1000 69.4 1.7 72.9 3.1 M4.2.1 M-4-2.1 I-3 500 70.0 1.6 73.9 1.7 M4.2.2 M-4-2.2 I-3 1000 t.b.d. t.b.d. Note: t.b.d.: to be determined.

(155) As can be seen from Table 10, even a low concentration of compounds I-1 and I-3 leads to a considerable improvement in the final value of the VHR after the exposure.

Examples 5.1 to 5.3

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

(157) TABLE-US-00032 Mixture M-5 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) = 0.112 .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

(158) As described in Example 4, mixture M-5 is also divided into several parts, and its stability to exposure to an LCD backlight is investigated as such and with various added compounds in a test cell having an alignment material for planar alignment and flat ITO electrodes.

(159) TABLE-US-00033 TABLE 11 VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 500 h (Ref.) M-5 None 0 88.5 1.0 73.4 1.2 C5.1 C-5-1 R-1 300 t.b.d. t.b.d. M5.1 M-5-1 I-1 300 88.8 0.9 84.2 2.2 M5.2 M-5-2 I-2 300 t.b.d. t.b.d. M5.3 M-5-2 I-3 300 t.b.d. t.b.d. Note: t.b.d.: to be determined.

(160) As can be seen from Table 11, even a low concentration of compound I-1 leads to a considerable improvement in the final value of the VHR after exposure to a backlight, both compared with the unstabilised reference mixture.

Examples 6.1 to 6.3

(161) The following mixture (M-6) is prepared and investigated.

(162) TABLE-US-00034 Mixture M-6 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

(163) ##STR00258##

(164) as reference substance and, for comparison, compound I-9

(165) ##STR00259##

(166) are added to this mixture. The results for test cells having the alignment layer AL-16301 are compiled in the following tables.

(167) TABLE-US-00035 TABLE 12a VHR(t)/% @ c(stab.)/ 60 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-6 None 0 96.2 89.1 C6.1 C-6-1 R-2 100 98.8 97.5 C6.2 C-6-2 R-2 500 98.7 97.8 C6.3 C-6-3 R-2 1000 98.5 98.0 M6.1 M-6-1 I-4 100 98.1 94.9 M6.2 M-6-2 I-4 500 99.6 99.4 M6.3 M-6-3 I-4 1000 99.5 99.2

(168) TABLE-US-00036 TABLE 12b VHR(t)/% @ c(stab.)/ 60 C., 1 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-6 None 0 58.5 35.4 C6.1 C-6-1 R-2 100 69.8 65.0 C6.2 C-6-2 R-2 500 63.9 62.8 C6.3 C-6-3 R-2 1000 60.9 61.5 M6.1 M-6-1 I-9 100 73.2 51.9 M6.2 M-6-2 I-9 500 91.5 87.5 M6.3 M-6-3 I-9 1000 90.4 85.9

(169) TABLE-US-00037 TABLE 12c VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-6 None 0 68.6 51.4 C6.1 C-6-1 R-2 100 78.1 75.2 C6.2 C-6-2 R-2 500 79.8 76.5 C6.3 C-6-3 R-2 1000 79.3 77.4 M6.1 M-6-1 I-9 100 83.4 . . . 76.2 . . . M6.2 M-6-2 I-9 500 93.1 . . . 92.9 . . . M6.3 M-6-3 I-9 1000 94.6 . . . 93.6 . . .

(170) TABLE-US-00038 TABLE 12d VHR(t)/% @ c(stab.)/ 100 C., 3 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 30 min (Ref.) M-6 None 0 23.7 17.3 C6.1 C-6-1 R-2 100 27.5 28.0 C6.2 C-6-2 R-2 500 27.8 27.6 C6.3 C-6-3 R-2 1000 26.3 26.9 M6.1 M-6-1 I-9 100 35.0 30.7 M6.2 M-6-2 I-9 500 55.5 56.0 M6.3 M-6-3 I-9 1000 61.3 56.7

(171) TABLE-US-00039 TABLE 12e VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 48 h (Ref.) M-6 None 0 71.8 61.8 C6.1 C-6-1 R-2 100 81.2 79.0 C6.2 C-6-2 R-2 500 80.7 81.3 C6.3 C-6-3 R-2 1000 79.3 81.4 M6.1 M-6-1 I-9 100 86.2 81.9 M6.2 M-6-2 I-9 500 94.4 94.5 M6.3 M-6-3 I-9 1000 93.5 94.0

(172) TABLE-US-00040 TABLE 12f VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 360 h (Ref.) M-6 None 0 71.8 52.6 C6.1 C-6-1 R-2 100 81.2 73.5 C6.2 C-6-2 R-2 500 80.7 78.8 C6.3 C-6-3 R-2 1000 79.3 80.1 M6.1 M-6-1 I-9 100 86.2 84.2 M6.2 M-6-2 I-9 500 94.4 92.4 M6.3 M-6-3 I-9 1000 93.5 91.7

(173) TABLE-US-00041 TABLE 12g VHR(t)/% @ c(stab.)/ 100 C., 60 Hz Ex. Mixture Stabiliser ppm t = 0 h t = 1.000 h (Ref.) M-6 None 0 71.8 52.7 C6.1 C-6-1 R-2 100 81.2 72.1 C6.2 C-6-2 R-2 500 80.7 77.2 C6.3 C-6-3 R-2 1000 79.3 78.7 M6.1 M-6-1 I-9 100 86.2 80.6 M6.2 M-6-2 I-9 500 94.4 83.6 M6.3 M-6-3 I-9 1000 93.5 80.8

(174) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(175) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.