Product Development Story
2. MAOC, AOC Development Story
3. OBBOC Development Story
OBBOC Development Story
4,4'-Oxybisbenzoyl chloride (OBBOC) is used as a monomer, but its high melting point makes it difficult to purify by distillation. A recrystallization method using thionyl chloride or phosphorus trichloride has problems with sulfur and phosphorus contaminants remaining in the product. |
The bottleneck was the inability to distill even the chlorine exchange reaction with benzotrichloride, which is our specialty. As mentioned earlier in the development story of OPC (WO 2010-013684: Japanese Patent 5649288: JP 2010-053126), OPC is our primary product. We continued the research to use it not only as a raw material for agricultural chemicals, but also as a chlorinating agent. Reaction of 4,4'-oxybisbenzoic acid with OPC was found to give OBBOC, however, it was difficult to purify via distillation.
We found a new synthetic method for Vilsmeier reagent from OPC with DMF, however, the phthalic anhydride byproduct remained in some solvents, and the solid Vilsmeier reagent could be isolated with high purity only by filtration. (Japanese Patent 57832331: JP 2012-136502)
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When the solid Vilsmeier reagent was treated with OBBA in 2-chlorotoluene with heat a slurry of OBBA gradually changed to OBBOC and dissolved in the solvent.
When cooled to room temperature, only OBBOC was precipitated as crystals, and DMF remained in the solvent. Filtration allowed for the isolation of high purity OBBOC
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As a result, it became possible to supply samples of OBBOC, but further cost reductions were required, so we have continued to examine a manufacturing method that could be implemented at our company. OBBA has low solubility in solvents, and chlorinating agents other than the Vilsmeier reagent required large amounts of solvent. Oxybisbenzaldehyde (OBBAD) has a low melting point of about 65 ℃ and was found to be highly soluble in various solvents. In fact, we were able to convert OBBAD to OBBOC efficiently by photo-chlorination. (Japanese Patent 6126440: JP 2014-201548)
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