QBr-compounds

Cathro et al. [48] found that the use of mixtures of QBr-compounds (Q = quaternary ammonium) may give a Hquid polybromide phase, even though the individual components form soHd or highly viscous polybromides. With the two... 

The role of bromide in DPC catalysis is still unclear. It was suggested that NR Br works as a base to ionize phenol to phenoxide anion [51] or as a surfactant to stabilize Pd(0) nanoparticles [65]. However, no other bases or surfactants have even come close to its activity in DPC synthesis. Quaternary ammonium and phosphonium bromides are expensive and difficult to recover in downstream processing and, therefore, have a substantial impact on the DPC cost structure. For the process economics, it was critical to replace these compounds with less expensive equivalents, which could be done by two ways either replacing QBrs with inexpensive NaBr or nonbromide nonquaternary salts. 

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