Complex Phenols

Coumarone—Indene Kesins. These should be called polyindene resins (17) (see Hydrocarbon resins). They are derived from a close-cut fraction of a coke-oven naphtha free of tar acids and bases. This feedstock, distilling between 178 and 190°C and containing a minimum of 30% indene, is warmed to 35°C and polymeri2ed by a dding 0.7—0.8% of the phenol or acetic acid complex of boron trifluoride as catalyst. With the phenol complex, tar acids need not be completely removed and the yield is better. The reaction is exothermic and the temperature is kept below 120°C. When the reaction is complete, the catalyst is decomposed by using a hot concentrated solution of sodium carbonate. Unreacted naphtha is removed, first with Hve steam and then by vacuum distillation to leave an amber-colored resin. It is poured into trays, allowed to cool, and broken up for sale. 

Nishioka and Fujita78) have also determined the Kd values fora- and (S-cyclodextrin complexes with p- and/or m-substituted phenyl acetates through kinetic investigations on the alkaline hydrolysis of the complexes. The Kd values obtained were analyzed in the same manner as those for cyclodextrin-phenol complexes to give the Kd(X) values (Table 5). The quantitative structure-activity relationships were formulated as Eqs. 30 to 32 ... 

With OH and SH, the nucleophilic substitution of Cl has been reported. Thus, with NaOH, there is a report of successful nucleophilic substitution in 50% aq. acetone at room temperature to give the phenol complex in 36% yield. The latter is then spontaneously deprotonated to give the cyclohexadienyl complex (Eq. (24)). An identical reaction was carried out using NaSH in MeCN (50% yield) to give the thiophenol complex which was deprotonated [72] Eq. (25). These reactions would be especially valuable because direct synthesis of the phenol or thiophenol complexes from ferrocene is not possible due to the strong interaction between the heteroatom and A1C13 [11, 19]. Recent improvement and use of this reaction were achieved [88],... 

Mn(II) > Mg(II).270 It should be underlined that titanium and zirconium alkoxides are efficient catalysts for both stages of reaction. Lanthanide compounds such as 2,2/-bipyridyl, acetylacetonate, and o-formyl phenolate complexes of Eu(III), La(III), Sm(III), Er(III), and Tb(III) appear to be even more efficient than titanium alkoxides, Ca or Mn acetates, Sb203, and their mixtures.273 Moreover, PET produced with lanthanides has been reported to exhibit better thermal and hydrolytic stability as compared to PET synthesized with the conventional Ca acetate -Sb203 catalytic system.273... 

Oxidation of the o-QM complex 13 (formed by treating the phenol complex with (R)-citronellal and pyridine) with CAN resulted in an intramolecular Diels-Alder reaction to form the benzo[c]chromene 15 (Scheme 3.8). 

One of the most significant differences between Arabica and Robusta coffees is in the caffeine content. Robusta coffees contain almost twice the caffeine found in Arabica coffees. There are some other differences recognized thus far Robustas contain almost no sucrose and only very small amounts of the kaurane and furokaurane-type diterpenes they contain higher proportions of phenols, complex carbohydrates (both soluble and hydrolyzable), volatile fatty acids on roasting, and sulfur compounds, all in comparison with Arabicas. References to these distinctions can be found in Chapter 6 of this book. 

A tetradentate ligand 2- bis[2-(2-pyridyl)ethyl]aminomethyl phenolate complexes zinc with an N30 donor set including pyridyl and phenolic groups. The X-ray structure reveals that a dimeric... 

It is considerably easier to induce an expansion of the periodicity along the c axis, since along this direction the layered structure is stabilized mainly by weaker dispersion forces. Indeed, the structural variation of the guest species caused a significant increase of the c axis from 14.845 A (for the phenol complex) to 15.818 A (for the p-cresol... 

The hydride-phenolate complexes OsH(OC6X5)(CO)(P Pr3)2 (X = H, F) react with molecular oxygen to give stable 1 1 adducts OsH(OC6X5)(CO)(r 2-02)... 

Swegat, W. Schlitter, I. Kruger, R Wollmer, A., MD simulation of protein-ligand interaction formation and dissociation of an insulin-phenol complex, Biophys. J. 2003, 84, 1493-1506... 

Sernetz, F. G. Mulhaupt, R. Fokken, S. Okuda, J. Copolymerization of ethene with styrene using methylalumi-noxane-activated bis(phenolate) complexes. Macromolecules 1997, 30, 1562-1569. 

This was initially formulated as in Fig. 35b, but on the basis of the structure of the phenol derivatives and reassessment of the spectroscopic data, the alternative formulation Fig. 35c is now preferred, with a switch in the oxygen bonding mode such as occurs in the phenol complex. 

Isaacson and Sawhney (60) studied the reactions of a number of phenols and smectite with transition metal (Cu, FeJ+) and nontransition metal exchangeable cations. IR spectra of the clay-phenol complexes showed that all the clays studied transformed the sorbed phenols. The transformation occurred to a much greater extent in clays with transition metal cations than in those with the non-transition metal cations. In a subsequent study, Sawhney et al. (61) studied the polymerization of 2,6-dimethylphenol on air-dried homoionic Na-, Ca-, A1-, and Fe-smectite at 50°C. A portion of the adsorbed 2,6-dimethylphenol was transformed into dimers, trimers, tetramers, and quinone-type compounds. The nature of the exchange cations had an effect on both sorption and transformation and decreased in the order Fe Al > Ca > Na. 

The ir spectrum of bis(phenolate) complexes has been interpreted in terms of a double minimum potential function (Kreevoy et ai, 1977 Kreevoy and Liang, 1980). With values of (p of ca. 0.3-0.4, points for these species probably lie close to the centre in Fig. 10. The point for the enol of 1, 1,1,5,5,5-hexafluoropentanedione with tp = 0.6 (Kreevoy and RidI, 1981)... 

Density functional calculations on the Dotz reaction leading from chromium carbene (75) with acetylene to give the phenol (78) suggested a new mechanism involving the formation of a chromahexatriene complex (77) from the initially formed vinylallyl-idene complex (76). " Complex (77) then collapses to the phenol complex (78). 

Dissociation of the Protein-Poly phenolic Complex and Characterization of the Polyphenolic Fraction. Since Indulin ATR is almost completely soluble in THF while the APPL s are quite insoluble in this solvent, but are soluble in DMF, a sequence of different percentage mixtures of these two solvents was used in order to dissociate the protein-lignin complexes for further analyses of the lignin part. 

Tejedor-Tejedor, M.L Yost, E.C. Anderson, M.C. (1990a) Characterization of benzoic acid and phenolic complexes at the goethite/ aqueous solution interface using cylindrical internal reflectance Fourier transform infrared spectroscopy. Part 5 Methodology. Langmuir 6 979-987... 

Poly(2,6-dimethylphenylene ether) can be prepared by dehydrogenation of 2,6-dimethylphenol with oxygen in the presence of copper(l) chloride/pyridine as catalyst at room temperature. It is known that the mechanism involves a stepwise reaction, probably proceeding via a copper phenolate complex that is then dehydrogenated. 

In irradiated potatoes, especially in some varieties and as a function of cultivating conditions of the raw material, after-cooking darkening may occur. This discoloration is attributed to formation of ferric-phenolic complexes. This phenomenon depends on the iron content, and is related to increased polyphenol formation and reduced citric acid levels, which are influenced by agronomic and climatic factors. Various technological measures have been developed to prevent this after-cooking darkening [23]. 

Stack and co-workers recently reported a related jx-rf / -peroxodi-copper(II) complex 28 with a bulky bidentate amine ligand capable of hydroxylating phenolates at - 80 °C. At - 120 °C, a bis(yu,-oxo)dicopper(III) phenolate complex 29 with a fully cleaved 0-0 bond was spectroscopically detected (Scheme 13) [190]. These observations imply an alternative mechanism for the catalytic hydroxylation of phenols, as carried out by the tyrosinase metalloenzyme, in which 0-0 bond scission precedes C - 0 bond formation. Hence, the hydroxylation of 2,4-di-tert-butylphenolate would proceed via an electrophilic aromatic substitution reaction. 

Interestingly, a homoleptic 2-mercapto phenolate complex c-[V(mcp)3] can be prepared from VO(acac)2 (as can the catecholato analog) by displacement of the acac and 0x0 ligands [54]. Similar to the catecholato complex, the structure is described as octahedral distorted toward trigonal prismatic. The redox features of this compound appear at values more negative than its catecholato analog. The Nernstian V(I V/V)... 

Crystallographic data for a Zn-phenol-pendant [12]aneN3 (226) revealed its TBP structure with extremely short equatorial phenolate-Zn2+ bond distance a water molecule is present at the apical position (227). It was observed that the deprotonation of phenol was promoted by coordination (pKa shifting from 9.2 (without zinc) to 6.8 with zinc and this has a direct bearing on the acidity of the CA phenol complex. 

Figure 7-18 Stereoscopic MolScript ribbon drawings of the B chains (A chains omitted) of (A) hexameric 2-zinc pig insulin. (B) A phenol complex of the same protein. Within each dimer the B chains are shaded differently. The Zn2+ ions are represented by white spheres and the coordinating histidine side chains are shown. Six noncovalently bound phenol molecules can be seen, as can several conformational differences. From Whittingham et al.B7 Courtesy of Peter C. E. Moody.

The formation of B-phenolic complexes can also affect the quantity of these compounds in the tissues. As indicated by Pilbeam and Kirkby [122], the bonding of B and caffeic acid blocks the formation of quinones, and therefore facilitates the synthesis and accumulation of phenolics. 

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