Phenoxide moiety

Most coordination catalysts have been reported to be formed in binary or ternary component systems consisting of an alkylmetal compound and a protic compound. Catalysts formed in such systems contain associated multinuclear species with a metal (Mt)-heteroatom (X) active bond ( >Mt X Mt—X > or — Mt—X—Mt—X— Mt = Al, Zn, Cd and X = 0, S, N most frequently) or non-associated mononuclear species with an Mt X active bond (Mt = Al, Zn and X = C1, O, S most frequently). Metal alkyls, such as triethylaluminium, diethylzinc and diethylcadmium, without pretreatment with protic compounds, have also been reported as coordination polymerisation catalysts. In such a case, the metal heteroatom bond active in the propagation step is formed by the reaction of the metal-carbon bond with the coordinating monomer. Some coordination catalysts, such as those with metal alkoxide or phenoxide moieties, can be prepared in other ways, without using metal alkyls. There are also catalysts consisting of a metal alkoxide or related compound and a Lewis acid [1]. 

When the ortho and para positions on the phenoxide are all substituted by alkyl groups, attack by oxygen of the phenoxide moiety is realized. Thus, for 2,4,6-trimethylphenoxide, the O-bonded adduct 12 was identified by 1H-NMR spectroscopy as well as by its characteristic electronic absorption spectrum (30, 31). However, a competitive displacement of N02 by phenox-... 

Tamao-Corriu coupling the effectiveness of DHTP over HTP can also be attributed to the increased probability for the lithium phenoxide moiety to be situated close to the palladium. 

On the other hand, the rapid and extensive association facilitated by protonation of kraft lignin phenoxide moieties as the pH of the aqueous solution is lowered, or when they are present in non-aqueous solvents, is presumably mediated by hydrogen bonding and/or dipolar interactions, with non-bonded orbital interactions remaining the primary intermolecular forces. It has been shown that the absolute molecular weights of associated kraft lignin complexes encountered in /V,/V-dimethylformamide (DMF) could exceed values 1000 times larger than those observed in aqueous alkaline solutions. ... 

The E-diethylstilbestrol-4 ,4 -semiquinone oxygen-centred radical is converted to a carbon centred radical which reacts with Oj forming a di-oxetane. Unless the dioxetane is rapidly protonated, it will almost instantly cleave into excited carbonyl products because of the intramolecular chemically initiated electron exchange luminescence. In the latter, electron transfer from the phenoxide moiety to the peroxide ring promotes the fluorescence observed from the singlet-excited 4-hydroxy propio-... 

The effect of the substitution at the ortho position of the phenoxide moiety was investigated utilizing complexes 35b,c and 40a,b (Figure 9.5) (Furuyama et al, 2005a). When activated with MAO at 25 °C, each complex produced PE with a narrow molecular-weight distribution = 1.05-1.16, up to 75 000 g/mol), however, reaction times... 

To obtain higher isoselectivity, Coates and coworkers systematically varied ortho-, meta-, and para-substituents on the phenoxide moiety in addition to the ketimine substituent in complexes 45a-q (Figure 9.6) (Edson et al., 2008). All the complexes produced PP with a narrow molecular-weight distribution 1.07-1.33, M = 3000-364000 g/mol)... 

Subsequent modifications to both the phenoxide and N-aryl moieties, relative to 50, have also been made. For example, 55 (Figure 15) contains a 2,6-F2C,5H3 N-aryl moiety and iodine substituents on the phenolate ring. When activated with MAO at 25 °C, 55 was reported to produce amorphous PP, which exhibited a narrow molecular weight distribution (M /Mn=1.17, Mn = 200000gmor ). Furthermore, complexes 56a and 56b employ 3,5-difluorophenyl N-aryl groups and substituents smaller than tert-butyl in the ortho position of the phenoxide moiety. Both 56a and 56b/MAO were shown to furnish amorphous PP ([rrrr] <0.48) with narrow molecular weight distributions (Mw/Mn= 1.13-1.16, M ... 

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