Catecholic phenols

MDB 2-(Methoxy methoxy) phenol 3-Methyl-catechol Phenol ... 

McBride and Wesselink (1988) studied IR spectra of catechol adsorbed onto the oxide surface and found evidence that the compound was chemically altered, indicating that chemisorption was the dominant mechanism. In addition to catechols, phenols are known to adsorb onto metal oxide surfaces. This adsorption is dependent on the number and position of hydroxy substitutions on the benzene ring. Diphenolic compounds adsorb to a greater extent than monophenolic compounds, suggesting the formation of a bidentate bond with the metal oxide. This bidentate bond is formed when the two phenolic ligands coordinate with one or two surface metal ions (McBride and Wesselink, 1988). 

Pyridine-2-aldoxime methochloride 345 Pyrogallol, catechol, phenol and p-cresol 363... 

Phenols in tobacco smoke (hydroxyquinone, resorcinol, catechol, phenol, isomeric cresols)... 

Analysis for Phenol, Hydroquinone, Benzoquinone, and Catechol Phenol, hy-droquinone, benzoquinone and catechol can be detected with the d)C18 column (ID = 3.91mm, length = 50mm) and a UV detector at working wavelength of 190-400nm. Methanol/water (1/1, V/V) can be selected as the mobile phase at a flow rate of 0.5 mL min-1. /10.2 un membrane filter is necessary before injection. 

Polyphenol Oxidases. Plant trichomes and their exudates confer resistance to a variety of insects (54-56). In solanaceous plants, such as the tomato and potato, trichomes contain polyphenol oxidases and catecholic phenolics (e.g., caffeic and chlorogenic acids), which contribute to resistance to a variety of insect pests. In the potato plant, the polyphenol oxidases and phenolics are separated in different trichomes. When insects, such as aphids or leaf hoppers, walk across the surface of the plant they break the two types of trichomes. Trichomal fluids are liberated and, upon mixing, polymerize as a result of polyphenol oxidase activity on catechols, forming an often lethal adhesive trap for the insects (52,58) In tomato plants, the polyphenol oxidase and chlorogenic acid are separated by intracellular compartments, but upon breakage of trichomes by insects, polymerization and physical entrapment occurs (54). 

Compounds such as catechols, phenols, aromatic amines and phenothi-azines may be easily oxidised, while quinones and some nitroaromatics... 

Risner, C.H. and S.L. Cash A high performance liquid chromatographic method for the determination of hydroquinone, resorcinol, catechol, phenol, m- + p-cresol, and o-cresol in tobacco smoke R DM, 1988, No. 233, September 2, see www.rjrtdocs.com 507039723 -9766. 

The siderophores fall into two main chemical types, with either catecholate-phenolate or hydroxamate donor groups. Several subdivisions of the hydroxamate siderophores are known, and additional examples continue to be identified. The siderophores, with a small number of... 

Within the single-ring product fraction, the guaiacols yield shown in Figure 12b reached 0.33 by about 10 min. Their second decomposition to catechols, phenols and char led to a rapid decrease in their yield to a vdue of 0.07 by 120 min. The yields of catechols and phenols reached about 0.08 and 0.16, respectively, by about 120 min. The catechols underwent secondary decomposition to phenols and char neither hydrocarbons nor anisoles formed. Thus, the tar fraction was composed primarily of compounds with two oxygen-containing substituents. 

Impact of Oxidative Enzymes on Aphids. Tomato plants are also attacked by a variety of other arthropods such as whiteflies, mites, and aphids (126,127). Trichomes have been studied as a basis of resistance against many of these arthropods (99). A consistent feature of resistance has been the allusion to the sticky entrapping properties of trichomes (type VI). We have shown that these entrapping properties result from the presence of compartmentalized catecholic phenolics and PPO/POD in the tips of type VI trichomes (99 unpubl. data), which upon breakage, for example by aphids, lead to quinone mediated pol3onerization of trichomal protein. This polymerized protein forms the classical blackened boots on aphid s feet. Utilizing a series of crosses... 

Methylation S-adenosyl- methionine Transmethylase (c)dosol) Catechols phenols amines histamine... 

Many important fine chemicals, including catechols, phenols, aldehydes and ketones, low molecular epoxides and diepoxides, medixun-chain alcohols, and terpenoids fall within the range of 1 < log Pq/w < 4. The discovery of solvent-tolerant bacteria leads to the new possibility of biocatalytic reaction systems containing organic solvents. By using solvent-tolerant bacteria, a variety of fine chemicals can be formed in microbial production processes. 

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