BISBI

J. M. Haschke, A. E. Hodges III, G. E. Bisby, and R. L. Lucas, Reaction ofPu with Water, REP-3416, Rockwell International, Golden, Colo., 1983. 

In turn, 1O2 is a very electrophilic excited state species of molecular oxygen that interacts efficiently with electron-rich molecules, such as aminoadd residues of proteins like histidine, metionine, tryptophan, tyrosine, etc., by both physical and chemical quenching processes, eqns. 9 and 10 (Davies, 2003 Bisby et al., 1999). 

I>A 0.52) and histidine as actinometer, since this aminoacid reacts completely with O2 with = 4 xlQ7 M-is-i, (Bisby et al., 1999). 

In the present case, = 1.1x10 M- s i, a typical value for the reaction of aminoacid moieties with 1O2 (Michaeli Feitelson, 1994 Bisby et al., 1999). By comparison with the total quenching rate constant, kfi = 2.7x10 M- s-i, it can be concluded that almost 60% of the interaction with 1O2 is through physical quenching and about 40% of the reactive moieties of GA are oxidized by 1O2. 

Adams, G.E., Bisby, RH., Cundall, R.B., Redpath, J.L. and Willson, RL (1972). Selective free radical reactions with proteins and enzymes. The inactivation of ribonuclease. Radiat. Res. 49, 290-298. 

Much progress has been made on regioselective hydroformylation of terminal alkenes in favor of the linear product. In particular bidentate phosphine or phosphite ligands, which have a natural bite angle 9 of about 110°, will favor the linear product. The most successful ligand types are BISBI [49, 50], BIPHEPHOS [51,52], and XANTPHOS systems (Scheme 8) [53]. 

A variant of the BISBI ligand system is the NAPHOS ligand, which as expected gives similar levels of n-selectivity in the course of the hydroformylation of terminal alkenes. Interesting is a hydroformylation in the presence of secondary amines which allows a mild and selective one-pot hydroformy-lation/enamine formation (Scheme 13) [58]. 

The synergistic effect observed in the presence of all three antioxidants implies that there is an interaction between the individual antioxidant components. The direct interaction of the a-tocopherol radical and ascorbic acid is already well established (Bisby and Parker 1995) and a study by Mayne and Parker (1989) on chicks deficient in vitamin E and selenium showed that the... 

Bisby, R.H. and Parker, A.W. 1995. Reaction of ascorbate with the a-tocopheroxyl radical in micellar and bilayer membrane systems. Arch. Biochem. Biophys. 317 170-178. 

A few sulfonated bidentate ligands have been used for which the coordination behavior has been well established for their nonsulfonated analogs the sulfonated ligands showed a behavior that was very much the same as that of their parent ligands in organic solvents. NAPHOS as in rhodium complex (127) behaves the same as BISBI (58), as does its sulfonated analog BINAS (128), which was developed and extensively studied by Herrmann and co-workers.410"413 The catalytically active rhodium complexes [HRh(CO)2(P-P)] of NAPHOS and BINAS have been characterized by IR and NMR spectroscopy.414... 

More recent advances in iridium-catalyzed aldehyde hydrogenation have been through the use of bidentate ligands [6]. In the hydrogenation of citral and cinnamaldehyde, replacing two triphenylphosphines in [IrH(CO)(PPh3)3] with bidentate phosphines BDNA, BDPX, BPPB, BISBI and PCP (Fig. 15.1) led to an increase in catalytic activity. 

Another bidentate ligand which shows improvements over triphenylphos-phine is that of BISBI [28]. The complex [RuCl2(PPh3)(BISBI)] shows selectiv-ities over 80%, but the yields are only 40-50% [28]. The analogous iridium complexes are less active, but show similar selectivity [6]. 

Figure 11.6 Effect of varying the water soluble phosphine ligand on the hydroformylation of propene to butyraldehyde. P Rh ratio = TPPTS 80 BISBIS 7 NORBOS 14 BINAS 7...

Diphosphines have also become very popular ligands since the late eighties in rhodium hydroformylation, e.g. Eastman s BISBI. The two-phase system underwent considerable improvements involving diphosphines [9],... 

Figure 8.2. Eastman s BISBI and typical diphosphites from Union Carbide Corporation...

Table 8.1. Hydroformylation results using BISBI and other ligands [33,39,56]...

Extending the speculations presented in Section 8.2 for PPh3 and its rhodium complexes one expected that BISBI would coordinate in a bis-equatorial fashion (14) in RhH(L-L)(CO)2, thus leading to 3t only when dissociation of a CO molecule takes place (due to strain in the backbone 3t might not be completely trans). NMR and IR spectroscopy proved [57] that the structure of complexes 11 indeed contained the two phosphorus atoms in the equatorial plane and hydrogen in one of the apical positions (14, Figure 8.9). 

L. Davenport, R. E. Dale, R. H. Bisby, and R. B. Cundall, Transverse location of the fluorescent probe l,6-diphenyl-l,3,5-hexatriene in model lipid bilayer membrane systems by resonance excitation energy transfer, Biochemistry 24, 4097-4108 (1985). 

Bisby, F.A. (2000) The quiet revolution biodiversity informatics and the Internet. Science, 289, 2309-12. 

F. A. Bisby (2000). The quiet revolution biodiversity informatics. Science 289 2309. 

The rate with BISBI is the highest as well (3-4000 TOF), with a ligand-to-metal... 

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