Water as a Green Solvent for Bulk Chemicals

Abstract

AbstractBulk chemicals industry rely mostly on heterogeneous catalysis; nevertheless, there are also several homogeneous processes applying soluble catalysts. This chapter describes those transition metal complex‐catalyzed processes for bulk chemicals in which the use of water as a solvent is a key element of technology and catalyst recovery. Water is used as the solvent in the biphasic hydroformylation of propene with a water‐soluble rhodium–sulfonated triphenylphosphine catalyst (the Ruhrchemie–Rhône‐Poulenc process) and in the telomerization of butadiene and water with a water‐soluble Pd(II)–phosphine catalyst (Kuraray process). These processes are described in detail and compared with those in which organic solvents are used. Other hydroformylation processes treated in this chapter use water as a solvent for induced phase separation and/or extraction. In general, the use of water allowed efficient catalyst recovery and recycle with losses in the lower ppb range and dramatic simplifications of technologies. In addition to its other advantageous properties, the non‐flammability and high heat capacity of water are outstandingly important characteristics for safety and in designing technological process details in the production of large quantities of chemicals. The overall result is characterized by improved economics and substantially reduced environmental impact.