Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2001-07-25
2002-12-24
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S570000, C430S572000, C430S566000, C430S567000, C430S607000, C430S613000, C430S614000
Reexamination Certificate
active
06498002
ABSTRACT:
The invention relates to a photographic material comprising a support and at least one layer which comprises at least one spectrally sensitised silver halide emulsion.
It is known that spectrally sensitised emulsions can be supersensitised by depositing compounds apart from sensitisers, particularly additional dyes, on the surface of the silver halide crystals, which compounds are capable of increasing the spectrally sensitised sensitivity. Ascorbic acid is a typical example of such compounds. Other suitable compounds are disclosed in U.S. Pat. Nos. 2,945,762, 3,695,888, 3,809,561 and 4,011,083. The supersensitisation of silver halide emulsions with catechol sulphonic acids is also known. The aforementioned compounds do have a super-sensitising effect, but result in an unwanted increase in fogging.
U.S. Pat. No. 5,457,022 describes supersensitisation by metallocenes. These are aromatic transition metal complexes of cyclopentadiene and derivatives thereof which have a characteristic “sandwich structure” without a direct metal-carbon &sgr; bond. The best known of these compounds are bis-(cyclopentadienyl)iron (ferrocene) and derivatives thereof. One disadvantage is that supersensitisation with ferrocenes results either in an unsatisfactory increase in sensitivity or is associated with an increase in fogging, during storage at the latest, due to which any increase in sensitivity is lost again.
With these known measures, however, no success has been achieved in obtaining photographic materials such as those which are currently required and which comprise a very high spectral sensitivity together with reduced fogging and a good shelf life, particularly when they are stored under humid climatic conditions.
The underlying object of the present invention is thus to identify photographic materials of increased spectral sensitivity which furthermore are distinguished by a high sensitivity/fogging ratio and by a good shelf life, particularly when stored under humid climatic conditions.
It has surprisingly been found that this object can be achieved by the addition of certain triazolines comprising thio- or selenoether radicals.
The present invention therefore relates to a photographic material comprising a support and at least one layer which comprises at least one spectrally sensitised silver halide emulsion layer, characterised in that the material contains at least one compound of formula
hereinafter also called compound I, wherein
X denotes sulphur or selenium,
R
1
denotes aryl or heterocyclyl,
R
2
denotes alkyl, alkenyl, alkynyl, aralkyl or hetarylalkyl,
R
3
denotes alkyl, alkenyl, aryl, aralkyl, hetaryl or hetarylalkyl, and
R
4
denotes H, alkyl, alkenyl, aryl, aralkyl, hetaryl or hetaralkyl, or
R
3
, together with R
4
, denotes the remaining atoms of a carbocyclic or heterocyclic ring.
Of the possible rings formed by the radicals R
3
and R
4
, saturated carbocyclic 4- to 6-membered rings are preferred.
The alkyl, aralkyl and alkenyl radicals in the sense of the present invention can be straight chain, branched or cyclic. The alkyl and alkenyl radicals can be substituted by aryl, heterocyclyl, hydroxy, carboxy, halogen, alkoxy, aryloxy, heterocyclyloxy, alkylthio, arylthio, heterocyclylthio, alkylseleno, arylseleno, heterocyclylseleno, acyl, acyloxy, acylamino, cyano, nitro, amino, thio or mercapto groups, for example, and the aryl, aralkyl, and heterocyclyl radicals can be substituted by alkyl, aryl, heterocyclyl, hydroxy, carboxy, halogen, alkoxy, aryloxy, heterocyclyloxy, alkylthio, arylthio, heterocyclylthio, alkylseleno, arylseleno, heterocyclylseleno, acyl, acyloxy, acylamino, cyano, nitro, amino, thio or mercapto groups, for example, wherein the term heterocyclyl represents a saturated, unsaturated or aromatic heterocycle and the term acyl represents the radical of an aliphatic, olefinic or aromatic carboxylic, carbamic, carbonic, sulphonic, amidosulphonic, phosphoric, phosphonic, phosphorous, phosphinic or sulphinic acid.
R
1
is preferably an unsubstituted or substituted phenyl, an unsubstituted or substituted pyridyl, an unsubstituted or substituted pyrimidyl, an unsubstituted or substituted thiazolyl or an unsubstituted or substituted tetrahydrothiophen-sulphone radical.
R
1
is most preferably an unsubstituted phenyl radical, a mono-or di-substituted phenyl radical, an unsubstituted tetrahydrothiophen-sulphone radical or a substituted thiazolyl radical.
In a further preferred embodiment, the R
2
radical contains polar substituents such as a phenol ether, pyridyl or carbonamide group.
Examples of preferred compounds of formula I are given below:
Compounds I-2, I-5, I-7, I-13, I-23, I-39 and I-40 are particularly preferred.
In the simplest case, for example, the preparation of triazoles of formula I which contain thioether groups is described by the etherification of a 4H-triazoline-3-thione with a reactive halide or sulphonic acid ester in the presence of bases.
Information on the preparation of 4H-triazoline-3-thiones is given, for example, in J. Heterocyclic Chem. 27 (1990) 2017-2020, in Liebigs Ann. Chem. 724 (1969) 226-228, in Synthesis 1990, 803-808 and 1048-1053, in Sci. Pharm. 51 (1983) 379-390 and in Chem. Ztg. 104 (1980) 239-240. The selenium compounds are prepared analogously.
Synthesis Example 1
Compound I-2 (1-phenyl-3,3-dimethyl-5-ethylthio-&Dgr;4-1,2,4-triazoline)
23 g potassium hydroxide (0.41 mol) was introduced over 30 minutes at 15° C. with stirring and cooling in ice into a batch comprising 83 g (0.4 mol) 1-phenyl-3,3-dimethyl-1,2,4-triazolidine-5-thione and 62 g (0.4 mol) ethyl iodide in 300 ml methanol. The batch was stirred at 20° C. for a further 1 hour, 15 g ethyl iodide and 6 g potassium hydroxide were added, and the batch was stirred at room temperature for a further 2 hours and 200 g ice were added. The batch was filtered under suction as soon as the ice had dissolved, and was washed with water and with a little methanol (80% by weight). The yellowish, crystalline product was purified by crystallisation from methanol (80% by weight) and was dried under vacuum at 40° C.
Yield: about 55 g of white needles (58% theoretical); melting point: 76-78° C.
Synthesis Example 2
Compound I-40 (1-phenyl-3,3-tetramethylene-5-ethylseleno-&Dgr;4-1,2,4-triazoline)
0.15 g potassium hydroxide were added with stirring to a batch comprising 0.56 g (0.4 mol) 1-phenyl-3,3-tetramethylene-1,2,4-triazolidine-5-selone, prepared by the reaction of cyclopentanone phenylhydrazone with glacial acetic acid and potassium selenocyanate at 50 to 60° C. by analogy with Liebigs Ann. Chem. 724, 226-228 (melting point 143° C.), and 0.35 g ethyl iodide in 10 ml methanol. After 45 minutes, 20 g ice were added thereto, the batch was filtered under suction as soon as the product became crystalline, and was washed with water and with a little methanol (80% by weight). The slightly reddish product was purified by recrystallisation from methanol (70% by weight) and was dried under vacuum at 40° C. As identified by thin layer chromatography, the product still contained about 5-10% of non-alkylated selone.
Yield: about 0.41 g of white needles; melting point: 72-75° C.
The compounds of formula I according to the invention can be hydrophobic or, in the presence of anionisable groups for example, can be hydrophilic. Moreover, in a preferred embodiment they can contain specific groups which improve their adsorption on a silver halide, e.g. thioether, selenoether, thio, thiol or amine radicals.
The preferred compounds of formula I are characterised in that their redox potential in aqueous solution, provided that it can be measured, differs by not more than +/−100 mV from the standard potential of the hydrogen electrode within the pH range between 5 and 7. In general, the redox potential of a compound I can readily be determined by cyclic voltammetry.
Compounds I can be added to the material at any point, in a preferred amount of 10
−6
to 10
−2
mol, particularly 10
−5
to 10
−2
mol per mol of total silver halide. This applies in particular to substances
Bergthaller Peter
Borst Hans-Ulrich
Siegel Jörg
Agfa-Gevaert
Letscher Geraldine
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