Compounds and liquid-crystalline medium

1. A liquid-crystalline medium, comprising

a) one or more compounds of the formula I

in which

R 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 2 — group or, if present, a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—, and one or, if present, a plurality of —CH 2 — groups may be replaced by —CH═CH— or —C≡C—, and in which one H atom or a plurality of H atoms may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 ,

R 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 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one —CH 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 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 13 , N(R 13 )(R 14 ) or R 15 , or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by OR 13 , N(R 13 )(R 14 ) or R 15 ,

R 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 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 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 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—,

S 11 and S 12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, in which one —CH 2 — group or, if present, a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 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 13 , N(R 13 )(R 14 ) or R 15 , or denote a single bond,

Y 11 to Y 14 each, independently of one another, denote methyl or ethyl,

Z 11 to Z 14 on each occurrence, independently of one another, denote —O—, —(C═O)—, —O—(C═O)—, —(C═O)—O—, —O—(C═O)—O—, —(N—R 13 )—, or ˜N—R 13 —(C═O)—, or additionally a single bond if S 11 is a single bond, provided that both Z 11 and Z 12 do not simultaneously denote —O—, and, provided that, if S 12 is a single bond, both Z 13 and Z 14 do not simultaneously denote —O—, and, provided that if —X 11 [—R 11 ] o — is a single bond, both Z 12 and Z 13 do not simultaneously denote —O—,

X 11 denotes C,

O. denotes an oxide radical,

p denotes 1 or 2,

o for formula I, denotes (3−p), and,

if p is 2,

n for formula I, denotes an integer from 2 to 4, and

m for formula I, denotes (4−n), and,

if p is 1,

n for formula I, denotes an integer from 5 to 10, and

m for formula I, denotes (10−n), and

denotes an organic radical having (m+n) bonding sites,

and where, in the case where p=1, —X 11 [—R 11 ] 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

in which

R 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 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,

in which

R 31 denotes an unsubstituted alkyl radical having 1 to 7 C atoms,

R 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 B1 and R 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 B1 and L 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 21 denotes n-propyl and R 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

in which

R 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 2 — group or, if present, a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—, and one or, if present, a plurality of —CH 2 — groups may be replaced by —CH═CH— or —C≡C—, and in which one H atom or a plurality of H atoms may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 ,

R 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 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one —CH 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 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 13 , N(R 13 )(R 14 ) or R 15 , or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by OR 13 , N(R 13 )(R 14 ) or R 15 ,

R 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 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 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 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—,

S 11 and S 12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, in which one —CH 2 — group or, if present, a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 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 13 , N(R 13 )(R 14 ) or R 15 , or denote a single bond,

Y 11 to Y 14 each, independently of one another, denote methyl or ethyl,

Z 11 to Z 14 on each occurrence, independently of one another, denote —O—, —(C═O)—, —O—(C═O)—, —(C═O)—O—, —O—(C═O)—O—, —(N—R 13 )—, or ˜N—R 13 —(C═O)—, or additionally a single bond if S 11 is a single bond, provided that both Z 11 and Z 12 do not simultaneously denote —O—, and, provided that, if S 12 is a single bond, both Z 13 and Z 14 do not simultaneously denote —O—, and, provided that if —X 11 [—R 11 ] o — is a single bond, both Z 12 and Z 13 do not simultaneously denote —O—,

X 11 denotes C,

p denotes 1 or 2,

o for formula I, denotes (3−p), and,

if p is 2,

n for formula I, denotes an integer from 2 to 4, and

m for formula I, denotes (4−n), and,

if p is 1,

n for formula I, denotes an integer from 5 to 10, and

m for formula I, denotes (10−n), and

denotes an organic radical having (m+n) bonding sites,

and where, in the case where p=1, —X 11 [—R 11 ] 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:

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,

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:

and

b) one or more compounds selected from the group of the compounds of the formula B,

in which

R B1 and R 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 B1 and L 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

in which

R 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 2 — group or, if present, a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—, and one or, if present, a plurality of —CH 2 — groups may be replaced by —CH═CH— or —C≡C—, and in which one H atom or a plurality of H atoms may be replaced by F, OR 3 , N(R 13 )(R 14 ) or R 15 ,

R 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 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—, a hydrocarbon radical which contains a cycloalkyl or alkylcycloalkyl unit and in which one —CH 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 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 13 , N(R 13 )(R 14 ) or R 15 , or an aromatic or heteroaromatic hydrocarbon radical, in which one H atom or a plurality of H atoms may be replaced by OR 13 , N(R 13 )(R 14 ) or R 15 ,

R 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 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 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 2 — group or a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 2 — groups cannot be replaced by —O—,

S 11 and S 12 on each occurrence, independently of one another, denote an alkylene group having 1 to 20 C atoms, in which one —CH 2 — group or, if present, a plurality of —CH 2 — groups may be replaced by —O— or —C(═O)—, but two adjacent —CH 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 13 , N(R 13 )(R 14 ) or R 15 , or denote a single bond,

Y 11 to Y 14 each, independently of one another, denote methyl or ethyl,

Z 11 to Z 14 on each occurrence, independently of one another, denote —O—, —(C═O)—, —O—(C═O)—, —(C═O)—O—, —O—(C═O)—O—, —(N—R 13 )—, or ˜N—R 13 —(C═O)—, or additionally a single bond if S 11 is a single bond, provided that both Z 11 and Z 12 do not simultaneously denote —O—, and, provided that, if S 12 is a single bond, both Z 13 and Z 14 do not simultaneously denote —O—, and, provided that if —X 11 [—R 11 ] o — is a single bond, both Z 12 and Z 13 do not simultaneously denote —O—,

X 11 denotes C,

O. denotes an oxide radical,

p denotes 1 or 2,

o for formula I, denotes (3−p), and,

if p is 2,

n for formula I, denotes an integer from 2 to 4, and

m for formula I, denotes (4−n), and,

if p is 1,

n for formula I, denotes an integer from 3 to 10, and

m for formula I, denotes (10−n),

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

denotes an organic radical having (m+n) bonding sites,

and where, in the case where p=1, —X 11 [—R 11 ] 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,

in which

R B1 and R 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 B1 and L B2 each, independently of one another, denote F or Cl.