Appeal No. 96-0700
Application No. 08/153,550
There is no dispute that Christmann discloses a process for
preparing a yellow pigment which is analogous to the claimed
process, i.e., Christmann utilizes tetrabromophthalic anhydride
as a reactant instead of the claimed tetrachlorophthalic
anhydride. We note "[a]ppellants agree that the process of
present claim 1 is analogous to the reaction disclosed in the
Christmann et al. reference" (page 4 of Brief). As with the
claimed reaction, the Christmann reaction is performed in the
presence of acetic acid as a solvent. Accordingly, based upon
the close similarity in chemical structure between the
chlorinated starting reactant of the claimed process and the
brominated starting material of the Christmann process, i.e., the
bromine substituent is the next adjacent element to chlorine in
the Group VIIA halogens, we concur with the examiner that it
would have been prima facie obvious for one of ordinary skill in
the art to replace the bromine substituents of Christmann with
the chlorine substituents of appellants with the reasonable
expectation that a useful pigment would be the resultant product.
Moreover, we find that the conclusion of obviousness is
substantially fortified by the disclosure of Hein which expressly
exemplifies the claimed reaction of tetrachlorophthalic anhydride
with o-phenphenylene diamine, albeit in a different acidic
solvent. In our view, not only would Hein strongly suggest
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