Silver halide photographic material - Patent Review 4409323

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The present invention relates to a silver halide photographic material containing a new compound of photographic application capable of releasing a photographically useful group in a controllable timing.

Various means are known to make use of a compound of photographic application in releasing a photographically useful group in correspondence with the image pattern. For example, U.S. Pat. Nos. 3,148,062, 3,277,554 and 3,705,801 disclose methods to release a development inhibitor, a photographic dye or a bleach inhibitor from the coupling site of the photographic coupler as a result of the reaction of such photographic coupler with the oxidized color developing agent. These compounds are induced to release a photographically useful group without adjustments to control the releasing timing.

Advancedly UK patent application GB No. 2010818A discloses a coupler which releases the photographically useful group on the color development with capability of control timing of the releasing. According to the description, the reaction of the coupler with the oxidized color developing agent leads to the first stage of cleavage, followed by an intramolecular nucleophilic displacement reaction, which causes the second stage of cleavage for the release of the photographically useful group, so, parameters may be controlled allowing adjustments over a wide range including those required for the timing of the effect exerted by the photographically useful group, the moving distance thereof, etc.

However, when the compound is used, the hydroxyl ion in the color developer also shares the nucleophilic displacement reaction, which results in a defect that the photographically useful group is released not only in exposed areas but in unexposed areas inspite of the expectation of the effect only in exposed areas, and that the controllable timing is limited to relatively shorter range.

The object of the present invention is to provide a compound free from the disadvantage mentioned above, and a photographic material containing the compound therein. More definitely the object is to provide a compound and a photographic material containing the compound, which is hard to decompose by hydroxyl ion and improved in a property of imagewise releasing a photographically useful group, on a coupling reaction, permitting control of time of release, rate of release, rate of diffusion, etc.

According to the present invention, the compound comprises a coupling group, a photographically useful group a timing group joining the coupler and photographically useful groups, which is cleavable from said coupler group on reaction with an oxidized color developing agent and the resulting cleaved timing and photographically useful group is able to undergo electron transfer along a conjugated system in the timing group whereby the photographically useful group is cleaved.

In the present invention, compounds that are preferable for use are represented by the formula as follows:

A-TIME-PUG (1)

where "A" is the coupler group capable of coupling reaction with the oxidized color developing agent, "TIME" the timing group and "PUG" the photographically useful group.

Any compound may be used for the coupler group A as far as it can react with the oxidized color developing agent to release the group -TIME-PUG. Examples of the coupler group include one which will form a colored product or a colorless product on coupling reaction with the oxidized color developing agent. The coupler group A may have no ballasting group or may be ballasted with an oil soluble or aliphatic group or groups. The group -TIME-PUG is attached to the component A at the coupling site, which is capable of coupling reaction with the oxidized color developing agent. The timing group joining the PUG and the component A may be an arbitrary organic group characterized by such a property that it can be cleaved from the PUG as a result of an electron transfer along a conjugated system toward PUG after the group -TIME-PUG is cleaved from the component A.

In the present invention, the term "conjugated system" refers to a form of bonding generally known as such in the field of chemistry, namely, the one in which a single bond and a double or triple bond appear alternatively in the chemical formula. Accordingly, it is assumed that the lone pair electron on the fragment -TIME-PUG cleaved from the component A is transferred along a conjugated system to ultimately break the bond between the TIME and PUG.

Examples of the timing group are formulated in the following formula: ##STR1## wherein the left hand side is attached to the coupler group, Z is O. S or ##STR2## R.sub.1, R.sub.2 and R.sub.3 are individually a hydrogen atom, alkyl or aryl group, Q ia 1,2- or 1,4-phenylene or naphthylene group. The phenylene or naphthylene may have a such substituent as halogen atom, alkyl, alkoxy, --CN, --NO.sub.2, --NHCOR or --COOR wherein R is alkyl.

In case the TIME group forms quinonemethide or naphthoquinonemethide on the final cleavage, the compound of the present invention includes one represented by the following general formula: ##STR3## where "A" and "PUG" are the same as defined in the general formula (1) while "X" represents atoms necessary to complete a substituted or nonsubstituted benzene or naphthalene nucleus and "R.sub.1 " and "R.sub.2 " individually represent a hydrogen atom, alkyl group or aryl group, with the group ##STR4## being joined at the para or ortho position relative to the oxygen atom.

The compound as represented by the above general formula (2) is cleaved as it reacts with the oxidized color developing agent, first forming a compound as represented by the following general formula (3), which is then recleaved through an electron transfer along the conjugated system to form a compound as represented by the following general formula (4) while releasing the PUG: ##STR5##

The above compound (4) is called either quinonemethide or naphthoquinonemethide.

Next, as an example of the compound of the present invention, a compound comprising a timing group which will ultimately form a quinonemethide compound and phenylmercaptotetrazole as the PUG is selected to illustrate the process of the present invention diagrammatically: ##STR6## where "CD" represents the oxidized color developing agent.

In the above diagram, upon the coupling reaction the compound of the present invention cleaves to release the timing group bonding to the photographically useful group (development inhibitor in this case), which is then recleaved by an electron transfer along the conjugated system as indicated by arrows to form orthoquinonemethide while releasing the development inhibitor.

Further, referring to a compound that uses a timing group other than the one used above as another example of the compound of the present invention, the process is again illustrated diagrammatically: ##STR7## where "A" and "CD" are the same as defined previously. Also in this case, in the fragment that is released from the compound after its reaction with CD' a lone pair electron located on the oxygen atom is conjugated with the carbonyl .pi. electrons.

As for the coupling group capable of undergoing a coupling reaction with the oxidized color developing agent, residues of couplers generally employed in the color photographic material are cited.

For example, for the yellow coupler, benzoylacetanilide derivatives or pivaloylacetanilide derivatives as disclosed