What Are Phenols

Phenol A compound that contains an —OH group bonded to a benzene ring. 

The functional group of a phenol is a hydroxyl group bonded to a benzene ring. We name substituted phenols either as derivatives of phenol or by common names  

Phenols are widely distributed in nature. Phenol itself and the isomeric cresols (a-, Tfh, and /vcresol) are found in coal tar. Thymol and vanillin are important constituents of thyme and vanilla beans, respectively  

Eugenol, which can be isolated from the flower buds (cloves) of Eugenia aromatica, is used as a dental antiseptic and analgesic. Urushiol is the main component in the irritating oil of poison ivy. 

Phenols and alcohols both contain an —OH group. We group phenols as a separate class of compounds, however, because their chemical properties are quite different from those of alcohols. One of the most important of these differences is that phenols are significantly more acidic than are alcohols. Indeed, the acid ionization constant for phenol is 10 times larger than that of ethanol  

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What are phenolic compounds They are compounds that have one or more hydroxyl groups attached directly to an aromatic ring. Phenol (1.1) is the structure upon which the entire group is based. The aromatic ring in this case is, of course, benzene. 

How do we know that water is a weaker acid than phenol What are their respective p/Ca values ... 

Tuomi J, Ilvessalo H, NiemelaP, Siren S, Jormalainen V (1989) Within-plant variation in phenolic content and toughness of the brown alga Fucus vesiculosus L. Bot Mar 32 505-509 Underwood AJ (2000) Experimental ecology of rocky intertidal habitats what are we learning J Exp Mar Biol Ecol 250 51-76... 

What are the main error sources in PAC experiments One of them may result from the calibration procedure. As happens with any comparative technique, the conditions of the calibration and experiment must be exactly the same or, more realistically, as similar as possible. As mentioned before, the calibration constant depends on the design of the calorimeter (its geometry and the operational parameters of its instruments) and on the thermoelastic properties of the solution, as shown by equation 13.5. The design of the calorimeter will normally remain constant between experiments. Regarding the adiabatic expansion coefficient (/), in most cases the solutions used are very dilute, so the thermoelastic properties of the solution will barely be affected by the small amount of solute present in both the calibration and experiment. The relevant thermoelastic properties will thus be those of the solvent. There are, however, a number of important applications where higher concentrations of one or more solutes have to be used. This happens, for instance, in studies of substituted phenol compounds, where one solute is a photoreactive radical precursor and the other is the phenolic substrate [297]. To meet the time constraint imposed by the transducer, the phenolic... 

The intermolecular coupling of phenols is used extensively in what are believed to be biomimetic alkaloid syntheses. Aqueous solutions of iron(lll) salts are most frequently used as the oxidising agent and the dimerization process must involve phenoxy radicals. Examples are the dimerization of orcinol 21 [114] and the formation of bis-benzyltetrahydroisoquinolines 22 [115],... 

Write out the complete reactions for production of PMMA and phenol-formaldehyde, as sketched in Figure 11-11. What are the advantages and disadvantages of an integrated chemical plant compared to separate plants to prepare individual chemicals and polymers ... 

Problem 19.12 What are the effects of ( ) electron-attracting and (b) electron-releasing substituents on the acid strength of phenols ... 

Describe the color of the reaction mixtures just before loading onto the column. Make observations about the column development process. Analyze the absorbance data by preparing an elution curve. On graph paper or a computer graphics program, plot 520 (j-axis) versus fraction number. How many peaks were obtained What are the components represented by each peak Use this elution curve to explain the action of a gel filtration column. Explain the fact that phenol red is present in both colored fractions. In what fraction is the bovine serum albumin ... 

How can the size dependent reactivity be rationalized and what are the important factors which are responsible for this cluster size reactivity Experiments have been performed with 1-naphthol associated with other molecules (Knochenmuss et al. 1988 Knochenmuss and Leutwyler 1989). Naphthol undergoes proton transfer with two molecules of piperidine. For phenol, one needs three of four ammonia or three monoethylamine (MEA) molecules for the same process. 

Write down your conclusion. To what degree are phenolics levels correlated with levels of herbivory Are there outliers that do not fit a general trend ... 

What are the properties of the heterocyclic systems or amines to be employed Do they contain groups sensitive to heat or reactive groups such as alcoholic or phenolic hydroxyls that have to be protected ... 

Antioxidants are classified as primary or secondary, depending upon how they react. Hindered phenols are primary antioxidants and function by donating a hydrogen to convert a peroxy radical to a hydroperoxide. Phosphites are among what are called secondary antioxidants and function as hydroperoxide decomposers. The ultimate outcome of these reactions is to convert the polymer bound radical to derivatives that are less destructive to the polymer. 

Thermal destruction systems have become recognized over the past decade as an increasingly desirable alternative to the more traditional methods of disposing of hazardous wastes in landfills and injection wells. What are some of the problems in the combustion of substances such as methylene chloride, chloroform, trichloroethylene, waste oil, phenol, aniline, and hexachloroethane ... 

What is the major acid gas component, and what are the more minor acid gases present in flue gas that provide a low cost way to acidify aqueous alkaline waste water streams to assist recovery of pollutants, such as phenols and hydrogen sulfide ... 

The physical properties determined using the ECD are important to different areas of chemistry. Analytical chemistry deals with how much and what are involved in a chemical reaction. Expressed differently, it establishes what we refer to as the QQQ quantitation, qualitative identification, and the quality of the results. The determination of the electron affinities of the chlorinated biphenyls, dioxins, and phenols and the prediction of the response of the ECD and NIMS are important to qualitative and quantitative analyses of environmental pollutants [21]. Polarographic reduction in solutions likewise gives accurate and precise qualitative and quantitative results. The quality of the analyses is expressed by the random and systematic uncertainties in the reported values. These are obtained from the same principle of weighted least squares used to obtain information from ECD data. Wentworth has described the application of the general least-squares procedure to chemical problems [22, 23]. 

Define the phenol compounds. What are the differences between alcohols and phenols ... 

A column having an inside diameter of 14 mm is filled with silica gel d= 0.61 g/cm ) containing 10% water by weight, 15 g being required and filling the tube to the 25 cm level. Calculate A . The values for pyrogallol and phenol were 0.51 and 0.97, respectively. What are the partition coefficients ... 

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