How is Disodium 2,2'-[(E)-1,2-ethenediyl]bis{5-[(E)-(4-hydroxyphenyl)diazenyl]benzenesulfonate} (CAS: 3051-11-4) typically synthesized?

Disodium 2,2'-[(E)-1,2-ethenediyl]bis{5-[(E)-(4-hydroxyphenyl)diazenyl]benzenesulfonate} (CAS: 3051-11-4) is typically synthesized via a multi-step process involving the diazotization of 4-hydroxyphenyl benzene followed by coupling with an azo derivative. The reaction is catalyzed by various reagents, and the overall process requires careful control of pH and temperature to achieve the desired yield and selectivity. Commonly used solvents include acetic acid and water.