Series Cascade

In 1991, Newkome and Lin 121 reported a series of acid terminated poly(ether amido) dendrimers (e.g., 3, 4), generated from the tetraacid core (1) and sequential use of the amino acid building block 2 (Scheme 7.1). These acid-terminated dendrimers were readily transformed 131 into the related polytryptophane analogues (5-7) by treatment with tryptophane methylester hydrochloride employing a common peptide coupling procedure (DCC 1-HBT in DMF). 141 The resultant chiral cascade series was examined via ORD/CD and the preliminary data indicate a linear relationship between optical rotation and the number of surface tryptophane moieties. 

Fibrin is the protein fiber that forms a blood clot. Fibrin is produced from the precursor, fibrinogen, as the last step in a cascading series of covalent modifications of blood proteins (Figure 11.42). The enzymatic cleavage of the inactive fibrinogen to form active fibrin is catalyzed by the enzyme, thrombin. 

Sodium Benzenesulfonate. Benzenesulfonic acid prepared continuously in a cascade series of six 2,000-gal cast-iron vessels is fed to a neutralizer system. Sodium sulfite slurry from reaction (3) is fed into the neutraliza tion tank at a constant rate while the benzenesulfonic acid flow is regulated to keep the reaction mixture distinctly acid. Sulfur dioxide is liberated [Eq. (2)] and piped for acidification of sodium phenoxide [Eq. (4)], and some is sent to another plant for purification and liquefaction. 

Another early paper was that of Robinson and Roberts (1957) who derived mathematical relationships for residence times, and hence the CSDs, in a cascade series of perfectly mixed crystallizers (section 9.1.2). 

Liquid monomer is polymerized in continuous stirred tank reactors in a number of processes. The Hypol process, developed by Mitsui Petrochemical, uses a cascaded series of stirred reactors for homopolymerization, followed by fluidized bed gas-phase reactors for copolymerization (274). El Paso (now Himtsman) converted the Rexall liquid monomer process to use high yield catalysts eliminating the sections required for deashing and removal of atactic material (275). Shell (now Basell) developed the LIPP process to produce homopolymers and random copolymers, using their high yield catalysts. 

The reader should note that calculations involving a cascade (series) of CSTRs are normally solved algebraically, not graphically. 

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