Biphenol phenol

Palladium may also show exceptional selectivities. as in the conversion of o,o -biphenol to o-(2-hydroxycyclohexyl)phenol (55), or p-phenylphenol to p-cyclohexylphenol (90%). If this latter reduction is continued in methanol solvent, the main product is not 4-cyclohexylcyclohexanol, but rather 4 cyclohexylcyclohexyl methyl ether (84%) (5d). 

However, many salts such as the hydroquinone or biphenol salt are so insoluble diat they do not work well by this procedure. Furthermore, a stoichiometric amount of base used for die reaction is critical to obtain high-molecular-weight polymers. Moreover, die sd ong base may undesirably hydrolyze the dihalides to afford deactivated diphenolates, which upset the stoichiometry. Clendining et al. reported that potassium carbonate or bicarbonate could be used in these reactions instead of corresponding hydroxides.60 McGrath and co-workers were the first to systematically study die use of the weak base K2C03 instead of a strong base to obtain phenolate salts.8,61,62 Potassium carbonate was found to be better than... 

Previous studies by Sorokin with iron phthalocyanine catalysts made use of oxone in the oxidation of 2,3,6-trimethylphenol [134]. Here, 4 equiv. KHSO5 were necessary to achieve full conversion. Otherwise, a hexamethyl-biphenol is observed as minor side-product. Covalently supported iron phthalocyanine complexes also showed activity in the oxidation of phenols bearing functional groups (alcohols, double bonds, benzylic, and allylic positions) [135]. Besides, silica-supported iron phthalocyanine catalysts were reported in the synthesis of menadione [136]. 

Various bisphenol derivatives were also polymerized by peroxidase under selected reaction conditions, yielding soluble phenolic polymers. Bisphenol-A was polymerized by peroxidase catalyst to give a polymer soluble in acetone, DMF, DMSO, and methanol. The polymer was produced in higher yields using SBP as a catalyst. This polymer showed a molecular weight of 4 x 10 and a 7g at 154°C. The HRP-catalyzed polymerization of 4,4 -biphenol produced a polymer showing high thermal stability. ... 

Several other minor metabolites of phenol have been identified in vitro. The formation of 1,4-dihydroxybenzene and 1,2-dihydroxybenzene in a 20 1 molar ratio was observed in isolated rat liver microsomes incubated with phenol (Sawahata and Neal 1983). Further catalysis to / -benzoquinone, 4,4 -biphenol, and biphenoquinone has been demonstrated in microsomes and in in vitro peroxidase preparations. The benzoquinone products react nonenzymatically with nucleophiles, including cysteine and reduced glutathione, to yield. V-conjugates of 1,4-dihydroxybenzene and 4,4-biphenol (Eastmond et al. 1986 Lunte and Kissinger 1983 Subrahmanyam and O Brien 1985). 

Of the many types of phenolic compounds, not many have been shown to possess AChE inhibitory activity. The root and stem bark of Magnolia officinalis Rehd. Et Wils. contains the biphenolic lignans, honokiol (72) and magnolol (73). Both lignans increased ChAT activity and inhibited AChE activity in vitro, and increased hippocampal ACh release in vivo) These two compounds also appeared to have antioxidant antiinflammatory... 

The Ullmann coupling is the classical example of Cu-catalyzed biaryl coupling, wherein (a) a phenol and arylhalide substrate are converted to a bis-arylether or (b) two arenes are coupled to form a bis-arene species. These coupling reactions are of great importance for general organic synthesis as well as pharmaceutical and fine chemicals. The copper-catalyzed phenol coupling to arrive at chiral biphenol derivatives is used extensively as a test reaction for the catalytic activity of new copper complexes [254,255]. 

The preparation of the related high molecular weight poly-1.4-phenylene sulfide has been accomplished by heating />-bromothio-phenolate salts in pyridine at 250° C (57). The commercially available polyethersulfones are reported to be prepared by condensation of 4.4 -dichlorodiphenyl sulfone with salts of biphenols in solvents such as dimethylsulfoxide at 150° C. The work of Bacon and Hill would suggest that both of these reactions might be carried out at considerably lower temperatures with copper (I) salts as catalysts. In addition, it has been demonstrated that copper (I) acetylides react quantitatively with aromatic iodides to yield tolanes (15, 77) therefore this reaction should also be the basis for a similar polymer forming reaction. 

Phenols act as acids toward [ (tmpa)Cu 2(02)]2+ (3) and Cu2(XYL—O—)(02)] + (8), hydronating them to give hydrogen peroxide and phenoxo-copper(II) complexes. However, hydrogen-atom abstraction takes place when complex [Cu2(N4)(02)]2+ (15) is reacted with phenols, giving phenoxy radicals that dimerize to produce biphenols or diphenoquinones, depending on the position of the substituents on the phenols. This shows that 15 is a better one-electron oxidant than 3 or 8. 

Some simple biphenols equipped with methyl groups, e.g., 3,3, 5,5 -tetramethyl-2,2 -biphenol 38, have attracted attention as important components of highly potent ligand systems [75-86]. Remarkably, the sustainable synthesis of such biphenols is rather challenging despite their simple scaffolds. In particular, methyl-substituted phenols are prone to side reactions. This is especially the case when 2,4-dimethyl-phenol (37) is oxidatively treated. Upon anodic conversion 37 is preferably transformed into polycyclic architectures [87]. Direct electrolysis in basic media provided only traces of the desired biphenol 38 and the dominating components of the product mixture consisted of Pu in meter s ketone 39 and the consecutive pentacyclic spiro derivative 40 [88]. For an efficient electrochemical access to 3,3, 5,5 -tetramethyl-2,2,-biphenol (38) we developed a boron-based template strategy [89, 90]. This methods requires a multi-step protocol but can be conducted on a multi-kilogram scale (Scheme 17). 

Isolated biphenol bCurrent efficiency c0.01 mol phenol d0.005 mol phenol e0.012 mol phenol... 

The stoichiometric coupling of phenols to biphenols by oxidation with manganic tris(acetylacetonate) has also been reported,343 e.g.,... 

Reagents. Para-Bis-A polymerization-quality bisphenol-A (Dow Chemical Co.) was recrystallized once from toluene. Pfaltz and Bauer s 4,4 -dichlorodiphenylsulfone was recrystallized three times from ethanol. Reagent phenol (Baker) and 4,4 -biphenol (Eastman s white label) were used as received. Spectroquality methyl sulfoxide, dimethyl acetamide, and dimethylformamide (Matheson, Coleman, and Bell) were used as solvents. 3,5,3, 5 -Tetramethyldiphenoquinone and hexamethylphosphor-amide (Aldrich) were used as received. 

Chen and Eastmond (1995) showed that benzene metabolites can adversely affect human topoisomerases, enzymes involved in DNA replication and repair. No effect of any metabolite was seen on human topoisomerase I or for topoisomerase II for hydroquinone, phenol, 2,2 -biphenol, 4,4 -biphenol and catechol at concentrations as high as 500 pM. 1,4-Benzoquinone and 1,2,4-benzenetriol inhibited human topoisomerase II in vitro, at 500 and 250 pM without bioactivation. However, following bioactivation, phenol and 2,2 -biphenol showed inhibitory effects at doses as low as 50 pM, whereas 4,4 -biphenol inhibited topoisomerase II at concentrations of 10 pM. 

A whole series of high-performance polyester LCPs was introduced in 1985. They were assembled from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Polyarylates (PARs) - amorphous phenolic esters derived from aromatic dicarboxylic acids (mixtures of terephthalic acid and isophthalic acid) and biphenols such as bisphenol A - are produced by Amoco (Ardel ), Celanese (Durel ) and DuPont (Arylon ) at a volume of approx. 2000 t/a. 

Cyclic bis-alkoxo complexes of the type Cp2Ti(0-0) have been synthesized by reacting Cp2TiCl2 with HO-OH in the presence of sodium amide (HO-OH = substituted and unsubstituted dibasic phenols, biphenols, and binaphthols).1542... 

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