Aromatic hydroxyls

I-Naphthylamine readily diazotizes and couples to aromatic hydroxylic or basic compounds. It was thus used as a first component in a number of important monoazo dyes, but its use has been severely curtailed because of its potent carcinogenicity. It sulphonates to give naphthionic acid (l-naphthylamine-4-sul-phonic acid). 

H2O2 in the presence of HE/BE acts as an effective and economical reagent for aromatic hydroxylation (163). Hydroxylations of phenols and amines in similar high acidity media are very effective (163). Xylenes were hydroxylated by bis(trimethylsilyl) peroxide and AlCl in poor yields (164). 

Dmg metaboHsm may also produce toxic materials. Thus, the aromatic hydroxylation of hydrocarbons such as ben2pyrene produces the highly reactive and carcinogenic 1,2-epoxides. 

Zavitsas et al. added terms for the extent of hemiformal and paraformaldehyde formation. Hemiformal formation slows the methylolation reaction as does the presence of paraformaldehyde. They report that only monomeric methylene glycol appears to methylolate. They point out that the terms for the two polyoxy-methylene species partially cancel one another, as depolymerization of paraformaldehyde naturally occurs while hemiformal formation is increasing due to methylolation. They observe that hemiformals form only on the methylolphenol hydroxyls and not on the aromatic hydroxyl. They calculate that the average number of methoxy groups involved in each of the hemiformals is about two in addition to the original methylol. There is no selectivity for ortho versus para positions in hemiformal formation. 

It would not be unreasonable to suggest that the dipole moment of the phenolic system has a negative skew toward the aromatic hydroxyl and that the electronic repulsion of these groups in an ortho-ortho situation greatly reduces the likelihood... 

Removal of one of the aromatic hydroxyl groups gives an agent similar to epinephrine in its effects but with longer dura-... 

The isomer of isoproterenol in which both aromatic hydroxyl groups are situated meta to the side chain also exhibits bron-chiodilating activity. Oxidation of 3,5-dimethoxyacetophenone by means of selenium dioxide affords the glyoxal derivative (15). Treatment of the aldehyde with isopropylamine in the presence of... 

Replacement of the aromatic hydroxyl groups in isoproterenol by chlorine again causes a marked shift in biologic activity. 

Aromatic nitroso compounds usually are considered to be intermediates in the hydrogenation of a nitroaromatic compound to the aromatic hydroxyl-amine or amine. However, nitroso compounds do not accumulate in these reductions, suggesting that they are reduced more easily than are nitro compounds. Catalysts effective for the nitro group should also be effective for nitroso. 

About half of the dissolved organic carbon may appear in humic or fulvic acids. These are high-molecular weight organic compounds of a composition which is somewhat uncertain. They contain aromatic hydroxyl and carboxyl groups which have the ability to bind to metal ions. Rivers and estuaries typically contain 10 mg/liter of acid with an exchange capacity of 5-10 mmol/g, mainly due to carboxylic... 

Figure 18.2 Representative receiver operator curves to demonstrate the leave n out validation of K-PLS classification models (metabolite formed or not formed) derived with approximately 300 molecules and over 60 descriptors. The diagonal line represents random. The horizontal axis represents the percentage of false positives and the vertical axis the percentage of false negatives in each case. a. Al-dealkylation. b. O-dealkylation. c. Aromatic hydroxylation. d. Aliphatic hydroxylation. e. O-glucuronidation. f. O-sulfation. Data generated in collaboration with Dr. Mark Embrechts (Rensselaer Polytechnic Institute).

Borodina Y, Rudik A, Filimonov D, Kharchevnikova N, Dmitriev A, Blinova V, et al. A new statistical approach to predicting aromatic hydroxylation sites. Comparison with model-based approaches. J Chem Inf Comput Sci 2004 44 1998-2009. 

Smith RV, Erhardt PW, Leslie SW. Microsomal O-demethylation, A-demethyl-ation and aromatic hydroxylation in the presence of bisulfite and dithiothreitol. Res Commun Chem Path Pharmacol 1975 12 181-4. 

AROMATICS HYDROXYLATION WITH NITROUS OXIDE 2.1. Discovering zeolite catalysts... 

Acronycine 0 0CH3 Cunninghamella echinulata NRRL 3655 Cunninghamella bainieri ATCC 9244 Aromatic hydroxylation [25]... 

Smith RV, Rosazza JP (1974) Microbial models of mammalian metabolism. Aromatic hydroxylation. Arch Biochem Biophys 161(2) 551-558... 

Other dialdehydes, keto aldehydes, hydroxyl aldehydes, ortho-substituted aromatic dialdehydes, and ortho-substituted aromatic hydroxyl aldehydes have been claimed to be active in a similar way [459]. 

Endogenous or exogenous aromatic compounds such as phenols and phenolic acids react extremely rapidly with OH radicals to form a mixture of hydroxylated products (Halliwell et /., 1988). Indeed, aromatic hydroxylation serves as an efiective method for evaluating OH radical activity both in vitro (Moorhouse et al., 1985 Grootveld and Halliwell, 1986a) and in vivo (Grootveld and Halliwell, 1986b). 

Kaur, H., Fagerheim, L, Grootveld, M., Puppo, A. and Halliwell, B. (1988). Aromatic hydroxylation of phenylalanine as an assay for hydroxyl radicals application to activated human neutrophils and to the haem protein leghaemoglobin. Anal. Biochem. 172, 360-367. 

A relatively stable QM is produced by initial P450-catalyzed aromatic hydroxylation of the SERM tamoxifen to yield 4-hydroxytamoxifen, followed by a cytochrome P450-catalyzed direct two-electron oxidation (Scheme 10.9).7 58 This QM is extremely long lived at physiological pH and temperature (tl/2 3 h, Table 10.2),59 most likely... 

Aromatic hydroxylation Aliphatic hydroxylation AM Iydroxylalion N-, O-, 5-Dealkylation Deamination Sulfoxidation Af-Oxidation Dehalogenation... 

Encapsulated Cu—chlorophthalocyanines oxidize hexane at C-l using 02 and at C-2 using H202 as oxidants. The dimeric structure of copper acetate is intact when it is incorporated into the zeolite. This is a regioselective aromatic hydroxylation catalyst, which mimics the specificity of the monooxygenase enzyme tyrosinase.82,89 Zeolite NaY catalysts made with a tetranuclear Cu(II) complex were synthesized and characterized.90... 

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