Process for preparation of 2-equivalent 4-arylthio-5-pyrazolone magenta couplers
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United States of America Patent
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Jul 8, 1997
Grant Date -
N/A
app pub date -
Aug 1, 1996
filing date -
Sep 18, 1995
priority date (Note) -
Expired
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Abstract
A process for preparation of 2-equivalent 4-arylthio-5-pyrazolone magenta couplers comprises the steps of: (i) reacting a 4-equivalent 5-pyrazolone magenta coupler and a diaryldisulfide compound in the presence of 1,8-diazabicyclo-[5,4,0]-undecen-7-ene and an organic solvent to obtain a reaction product between 4-arylthio-5-pyrazolone magenta coupler and 1,8-diazabicyclo-[5,4,0]-undecen-7-ene, and (ii) converting the reaction product with an inorganic acid into the 4-arylthio-5-pyrazolone magenta coupler. The reaction product between the 4-arylthio-5-pyrazolone magenta coupler and the 1,8-diazabicyclo-[5,4,0]-undecen-7-ene is easily formed in high yield and purity. This reaction product, which is insoluble in the reaction solvent, can be easily isolated from the reaction mixture and converted by acidification into the 2-equivalent 4-arylthio-5-pyrazolone magenta coupler in high yield and purity.
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