How is 4,4'-[(E)-1,2-Diphenyl-1,2-ethenediyl]dibenzoic acid (CAS: 1002339-79-8) typically synthesized?

4,4'-[(E)-1,2-Diphenyl-1,2-ethenediyl]dibenzoic acid is typically synthesized via a two-step process. First, diphenylacetylene is reacted with phthalic anhydride under controlled conditions to form the intermediate. Then, the intermediate is oxidized to yield the final product. This synthesis involves the use of various reagents and catalysts, and the process requires precise temperature and pressure control to achieve high yield and selectivity.