Photographic useful group releasing system
AssigneeAgfa-Gevaert
InventorsJean-Marie Dewanckele, Johan Loccufier, Pierre De Clercq, Dirk Van Haver, Noel Hosten
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Abstract
A photographic element is disclosed containing a compound capable of releasing image-wise a photographic useful group (PUG) based on a mechanism involving radical formation under development conditions and splitting of a homolytically labile bond. In a preferred embodiment the compound capable of releasing the PUG is a hydrazine derivative or a 1-aryl-3-pyrazolidinone derivative.
Claims9
Photographic element comprising a support and at least one silver halide emulsion layer characterized in that said element further contains a compound which comprises in its molecular structure a redox moiety capable of forming a radical under photographic development conditions, said radical being capable of splitting by one or more consecutive reaction(s) a homolytically labile bond present in said same compound, thereby releasing a photographically useful group, wherein said compound corresponds to following general formula (I):
- Redox-Link-X-PUG (I)
- wherein,
- PUG together with X, defined hereinafter, represents a photographically useful group,
- Redox is a moiety capable of forming a radical under photographic development conditions,
- Link is (a) an optionally substituted methylene group, or (b) a divalent linking group having an endstanding carbon atom at the side bonded to X and containing at least one radical trapping functional group chosen from the following list, and present in the indicated position vis-a-vis the original position of the generated radical:
- (b.1) a Z.dbd.Y or Z.dbd.Y group, in the chain or exo positioned, in any of the fifth to ninth positions, wherein Z represents C, S or N, and Y represents C, S, O or N;
- (b.2) a C--H, C--Cl, C--Br, C--I or N--H group in any of the fifth to seventh positions;
- and
- (b.3) an aryl or a hetero-aryl group in any of the third to ninth positions;
- (b.4) a carbocyclic or heterocyclic three-membered ring in any of the fifth to ninth positions;
- with the proviso that after the final trapping of the radical the X-PUG group takes the .beta.-position vis-a-vis the final radical, and that there are no conformational restraints making this intramolecular reaction impossible;
- X represents --S--, --Se--, --Sn-- or SO.sub.2 --, --O-- or --N-- linked by one side to PUG, and by the other side to the endstanding carbon atom of Link thereby forming a homolytically labile bond.
Photographic element comprising a support and at least one silver halide emulsion layer characterized in that said element further contains a compound which comprises in its molecular structure a redox moiety capable of forming a radical under photographic development conditions, said radical being capable of splitting by one or more consecutive reaction(s) a homolytically labile bond present in said same compound, thereby releasing a photographically useful group, wherein said compound corresponds to following general formula (II):
- Redox-Link'-X'-PUG (II)
- wherein,
- PUG together with X', defined hereinafter, represents a photographically useful group,
- Redox is a moiety capable of forming a radical under photographic development conditions,
- Link' is a divalent linking group having an endstanding heteroatom at the side bonded to X' and containing at least one radical trapping functional group, and
- X' is a divalent linking atom, and wherein Link' and X' are chosen in such a way that the endstanding atom of Link' forms with X' a heteroatom-heteroatom homolytically labile bond chosen from the group consisting of S--S, N--S, N--Se, N--O, N--N and S--Sn, and positioned in any of the fourth to ninth positions vis-a-vis the original position of the generated radical.
Dependencies are inferred from the claim text.