Phenols in nature

Di Corcia A, Bellioni A, Madbouly MD, et al. 1996. Trace determination of phenols in natural waters. Extraction by a new graphitized carbon black cartridge followed by liquid chromatography and reanalysis after phenol derivatization. J Chromatogr 733 383-393. 

Dealkylations have been used in the regioselective conversion of methoxyaryl groups to phenols in natural products, particularly alkaloids 1471 such as papaverine (30), and in the production of mammalian metabolites by microbial biotransformation, as exemplified by the biotransformation of bisprolol (4). 

Table 5.6 shows the total phenolic content (determined using the Folin-Ciocalteu assay) and antioxidant activity (ABTS radical scavenging capacity) of extracts from morama bean seed coat and cotyledon prepared with acidified mefhanol. If is clear fhaf morama bean seed coat and cotyledon have appreciable levels of fofal phenolics and antioxidant activity. These phenolics are concentrated in the seed coat. It has been reported that the morama bean cotyledon contains high levels of the amino acid tyrosine (Maruatona et ah, 2010) which is phenolic in nature and can therefore confribufe fo fhe fofal phenolic content of the cotyledon as determined with the Folin-Ciocalteu assay. 

Ratanathanawongs and Crouch [19] have described an on-line post-column reaction based on air-segmented continuous flow for the determination of phenol in natural waters by high performance liquid chromatography. The reaction used was the coupling of diazotised sulphanilic acid with the phenol to form high coloured azo dyes. The detection limit for phenol was 17pg L 1 which represents a 16-fold improvement over determination of phenol with ultraviolet detection. 

Cashew nut shell liquid (CNSL) is the exudate from the cashew nut shell. It is mainly phenolic in nature. Industrially used for making polymeric resins etc. A bath of the CNSL is traditionally used for heating the whole nuts with shells. 

Indirect photolysis mechanisms involve the excitation of an additional compound called a photosensitizer (PS), which in its excited state can directly oxidize the pollutant of interest. This type of mechanism was investigated by Faust and Hoigne [82] using fulvic substances as photosensitizers of phenols in natural waters. These latter mechanisms correspond to the indirect photolysis of M. In fact, Faust and Hoigne [82] reported that there are four possible routes of the excited photosensitizing action ... 

Bosch F, Font G, Manes J. 1987. Ultraviolet spectrophotometric determination of phenols in natural and waste waters with iodine monobromide. Analyst 112 1335-1337. 

How are glycosides formed from phenols (in Nature or in the laboratory) Why is the stereochemistry of the glycoside not related to that of the original sugar ... 

Figure 7 Direct photochemical reaction pathway of Triclosan (5-chloro-2-(2,4-di-chlorophenoxy)phenol) in natural water (3-100 iM of Triclosan in pH-bujfered solutions), irradiated with a Hg-vapour lamp. Only the triclosan phenolate anion (present in water at pH >8) is susceptible to significant photochemical transformation and will also react through indirect photolysis (not shown) with singlet oxygen ( O2) and OH radicals to form 2,4-dichloro-phenol (2,4-DCP). The photoproduct 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) belongs to a notoriously persistent group of chemicals commonly referred to as dioxins ...

Zhao, R.S., Cheng, C.G., Yuan, J.P., Jiang, T., Wang, X., Lin, J.M. Sensitive measurement of ultratrace phenols in natural water by purge-and-trap with in situ acetylation coupled with gas chromatography-mass spectrometry. Anal. Bioanal. Chem. 387, 687-694 (2007)... 

Knutsson M, Mathiasson L, and Jdnsson JA. Supported liquid membrane work-up in combination with liquid chromatography and electrochemical detection for the determination of chlorinated phenols in natural water samples. Chromatographia 1996 42 165-170. 

By operating an air-blown, fluidized-bed reactor at about 590 to 600°C, Biocarbons Corporation has been able to produce a water-insoluble liquid product that is phenolic in nature. While product yields are lower than for fast pyrolysis processes designed to maximize liquid fuel production from biomass, the selectivity is 100% no further product separation is required before the oil can be used to make adhesive. 

A FIA system with CLD was proposed for determination of phenols in natural waters, based on the reaction with potassium permanganate in the presence of sulfuric acid. Preconcentration by SPE on XAD-4 resin lowers the LOD to 5 p.gL . The method has... 

Afghan, B. K., Belliveau, P. E., LaRose, R. H., and Ryan, J. F. (1974). An improved method for determination of trace quantities of phenols in natural waters. Anal. Chim. Acta 71, 355-366. 

A.L. Moskvin, L.N. Moskvin, A.V. Moszhuchin, V.V. Fomin, Extraction-chromatographic preconcentration with chromatomembrane separation of extract from aqueous phase for luminescence determination of oil products and phenols in natural water by flow injection analysis, Talanta 50 (1999) 113. 

Ethers There are very few ethers commonly found in essential oils and those that do are phenolic in nature. The two most important are anethol, which is found in aniseed, and methyl chavicol, which is found in basil and tarragon. The structures of anethol and methyl chavicol are shown in Figure 6. 

MS has proved to be a very powerful technique in the analysis of flavonoids and phenolic acids mainly due to its high sensitivity and the possibility of coupling with different chromatographic techniques such as gas chromatography (GC-MS), capillary electrophoresis (CE-MS), and especially LC-MS. Nowadays, techniques such as LC-DAD-MS, and particularly LC-DAD-electrospray ionization (ESI)/MS, are regarded as necessary tools for the analysis of phenolics in natural matrices. ... 

Sample preparation is a critical step for the analysis of phenolics in natural matrices and is far more critical for quantification than for identification. 

The active antioxidant component may be built in at either A or A and can be either amino or phenolic in nature. 

Being phenolic in nature, methyl salicylate may be extracted from solvent solution by aqueous potassium hydroxide, practically no hydrolysis occurring in the cold if the alkali solution is weak. Other methods of determination can be more advantageously discussed in the analysis of the preparations containing methyl salicylate, which are described below. 

Quirke, J. M. E. Hsu, Y.-L. Van Berkel, G. J. Ferrocene-based electroactive derivatizing reagents for the rapid selective screening of alcohols and phenols in natural product mixtures using electrospray tandem mass spectrometry. J. Nat. Prod. 2000, 63, 230-237. 

J. Brady and N. Griffiths, Upwind flight responses of tsetse flies (Glossina spp.) (Diptera Glossinidae) to acetone, octenol and phenols in nature A video study. Bull. EntomoL Res., 83, 329, 1993. 

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