Acyl- and bisacylphosphine derivatives

1. An acyl- or bisacylphosphine derivative of the formula (I)

where

R 1 is α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4-or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 2 , R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )OR 5 , —O(SO 2 )R 5 or —O(CO)Cl,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups.

2. An acyl- or bisacylphosphine derivative as claimed in claim 1 , where

Y is O, S or NR 3 ,

Z is O, S, NR 3 or a free pair of electrons,

FG is —Cl, —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )R 5 or —O(CO)Cl.

3. An acyl- or bisacylphosphine derivative as claimed in claim 1 , where

Y is O or S,

Z is O, S or a free pair of electrons,

FG is —Cl, —O(CO)R 5 , —O(CO)OR 5 or —O(SO 2 )R 5 .

4. An acyl- or bisacylphosphine derivative as claimed in claim 1 , where

Y is O,

Z is O or a free pair of electrons,

FG is —Cl or —O(SO 2 )R 5 .

5. An acyl- or bisacylphosphine derivative as claimed in claim 1 , where

R 1 is 2,4,6-trimethylphenyl, 2,6-dimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, or 2,4,6-trichlorophenyl, and

R 2 is phenyl or ethoxy.

6. A process for the preparation of an acyl- or bisacylphosphine derivative of the formula (I)

where

R 1 , R 2 , R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —F, —Cl, —I, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )Cl, —O(SO 2 )R 5 , —O(CO)Cl, —O(NO)OR 5 or, in the case where Z≠S, —SR 5 ,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups,

from a substance of the formula (II)

where

X is hydrogen or a cation,

which comprises reacting substance (II) with at least one agent which converts the —OX group into an —FG group.

7. A process as claimed in claim 6 , wherein substance (II) is reacted with phosgene (COCl 2 ), thionyl chloride (SOCl 2 ) or sulfuryl chloride (SO 2 Cl 2 ) in order to convert —OX into the group FG=—Cl.

8. A process as claimed in claim 6 , wherein substance (II) is reacted with R 5 SO 2 Cl or (R 5 SO 2 ) 2 O in order to convert —OX into the group FG=—OSO 2 R 5 .

9. A method of photoinitiation comprising photoinitiating a potopolymerizable compositions with an acyl- or bisacylphosphine derivative of the formula (I)

where

R 1 is phenyl, α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 2 , R 5 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore C 1 -C 18 -alkoxy is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocylic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )OR 5 , —O(SO 2 )R 5 or —O(CO)Cl,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups.

10. A method of photoinitiation comprising photoinitiating a potopolymerizable compositions with an acyl- or bisacylphosphine derivative of the formula (I)

where

R 1 is phenyl, α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 2 , R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore which is unsubstituted substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, and

FG is defined as follows:

FG —Br, —(NR 3 )—NR 4 R 9 , —(NR 3 )—OR 9 or —SR 3 (for Z=S), and

R 9 is hydrogen or C 1 - to C 4 -alkyl.

11. A photoinitiator mixture comprising at least one acyl- or bisacyiphosphine derivative of the formula (I)

where

R 1 is phenyl, α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 2 , R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore which is unsubstituted substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )OR 5 , —O(SO 2 )R 5 or —O(CO)Cl,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups.

12. A radiation-curable composition comprising at least one acyl- or bisacyiphosphine derivative of the formula (I)

where

R 1 is phenyl, α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 2 , R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore which is unsubstituted substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )OR 5 , —O(SO 2 )R 5 or —O(CO)Cl,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups.

13. A radiation-curable composition obtainable by reaction of at least one acyl- or bisacylphosphine derivative of the formula (I)

where

R 1 is phenyl, α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 2 , R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 2 is furthermore which is unsubstituted substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or is R 1 —(C═Y)—,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )OR 5 , —O(SO 2 )R 5 or —O(CO)Cl,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, and

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups,

with a compound containing free hydroxyl, amino, monoalkylamino, monoarylamino and/or mercapto groups.

14. A radiation-curable composition as claimed in claim 13 , wherein the compound is a polymerizable compound having a number average molecular weight M n of less than 20,000.

15. A radiation-curable composition comprising a photoinitiator mixture as claimed in claim 11 .

16. An acyl- or bisacylphosphine derivative as claimed in claim 2 , where

R 1 is 2,4,6-trimethylphenyl, 2,6-dimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl or 2,4,6-trichlorophenyl, and

R 2 is phenyl or ethoxy.

17. An acyl- or bisacylphosphine derivative as claimed in claim 3 , where

R 1 is 2,4,6-trimethylphenyl, 2,6-dimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl or 2,4,6-trichlorophenyl, and

R 2 is phenyl or ethoxy.

18. An acyl- or bisacylphosphine derivative as claimed in claim 4 , where

R 1 is 2,4,6-trimethylphenyl, 2,6-dimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl or 2,4,6-trichlorophenyl, and

R 2 is phenyl or ethoxy.

19. An acyl- or bisacyiphosphine derivative of the formula (I)

where

R 1 is phenyl, α-naphthyl, β-naphthyl, 2-, 3- or 4-chlorophenyl, 2,6- or 2,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2-, 3- or 4-methylphenyl, 2,6- or 2,4-dimethylphenyl, 2,4,6-trimethylphenyl, 2-, 3- or 4-ethylphenyl, 2,6- or 2,4-diethylphenyl, 2-, 3- or 4-iso-propylphenyl, 2-, 3- or 4-tert-butylphenyl, 2-, 3- or 4-methoxyphenyl, 2,6- or 2,4-dimethoxyphenyl, 2,6- or 2,4-diethoxyphenyl, methylnaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, cyclopentyl, cyclohexyl, 2,5-dimethylcyclopentyl, 2,6-dimethylcyclohexyl, 2,6-diethylcyclohexyl, 2,6-dimethoxycyclohexyl, 2,6-diethoxycyclohexyl, 2,6-dichlorocyclohexyl, 2,5-dichlorocyclopentyl, 2- or 3-furyl, 2- or 3-thiophenyl, 2- or 3-pyrryl, dimethylpyrryl or an ortho-substituted phenyl other than 2-methylphenyl, 2-methoxyphenyl or 2-chlorophenyl,

R 5 , R 6 and R 7 are C 1 -C 18 -alkyl, or C 2 -C 18 -alkyl, C 2 -C 18 -alkenyl, C 6 -C 12 -aryl or C 5 -C 12 -cycloalkyl, each of which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or are a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocyclic radical, where the said radicals may each be substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

Y is O, S, NR 3 , N—OR 3 or N—NR 3 R 4 ,

Z is O, S, NR 3 , N—OR 3 , N—NR 3 R 4 or a free pair of electrons,

R 3 is hydrogen, C 1 - to C 4 -alkyl, SO 3 H, phenyl or acetyl,

R 4 is hydrogen, C 1 - to C 4 -alkyl, COOR 3 , or C 6 -C 12 -aryl or arylsulfonyl, each of which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

FG is a leaving group having the structure —Cl, —CN, —OCN, —SCN, —N + R 6 R 7 R 8 , —O(CO)R 5 , —O(CO)OR 5 , —O(SO)Cl, —O(SO 2 )OR 5 , —O(SO 2 )R 5 or —O(CO)Cl,

R 5 is furthermore C 1 -C 18 -alkoxy, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals,

R 8 is C 1 -C 18 -alkyl, which is unsubstituted or substituted by aryl, alkyl, aryloxy, alkoxy, heteroatoms and/or heterocyclic radicals, or C 2 -C 18 -alkyl, which is uninterrupted or interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, and

R 2 is ethoxy.