Phenolic adds

The distillate may contain volatile neutral compounds as well as volatile acids and phenols. Add a slight excess of 10-20 per cent, sodium hydroxide solution to this distillate and distil until the liquid passes over clear or has the density of pure water. The presence of a volatile, water-soluble neutral compound is detected by a periodic determination of the density (see Section XI,2) if the density is definitely less than unity, the presence of a neutral compound may be assumed. Keep this solution Si) for Step 4. 

Procedure. Prepare four test solutions of phenol by placing 200 mL of boiled and cooled distilled water in each of four stoppered, 500 mL bottles, and adding to each 5g of sodium chloride this assists the extraction procedure by salting out the phenol. Add respectively 5.0, 10.0, 15.0 and 20.0 mL of the standard phenol solution to the four bottles, then adjust the pH of each solution to about 5 by the careful addition of 5M hydrochloric acid (use a test-paper). Add distilled... 

Both alcohols and phenols add to ketenes to give carboxylic esters (R2C=C= O+ROH —> R2CHC02R). This has been done intramolecularly (with the ketene end of the molecule generated and used in situ) to form medium- and large-ring lactones. In the presence of a strong acid, ketene reacts with aldehydes or ketones (in their enol forms) to give enol acetates. 

Decarboxylase Decarboxylation of amino adds and simple phenolic adds, primarily p-hydroxylated L-dopa, tyrosine... 

A new type of initiator containing the azido group has recently been described by Glowiak [164]. These are salts of heavy metals (e.g. lead), phenols of phenolic adds containing nitro groups and azido group, e.g. the plumbous salt of dinitro-azidophenol (XIII) and 5-nitro-3-azidosalicylic acid (XIV) ... 

Both alcohols and phenols add to ketenes to give carboxylic esters 80... 

In the presence of base, alcohols and phenols add l,5-diphenylpenta-l,4-diyn-3-one (72JOU1398). At 40 °C addition occurs at both triple bonds to give a mixture of the 1,5-dialkoxy compound (411), the triketone and the pyran-4-one. On treatment with acid the former compounds are converted into the pyranone. However, at 15 °C only one triple bond is attacked giving the alkoxyvinyl ethynyl ketone (412), but this also forms the pyranone with acid (Scheme 136). 

Rao, M. V. S. S. T. S. and Muralikrishna, G. (2001). Non-starch polysaccharides and bound phenolic adds from native and malted finger millet (ragi, Eleusine coracana, Indaf-15). Food Chem. TL, 187-192. 

Phenols add intramolecularly to Michael acceptors. " Under acidic conditions, a one-pot sequence starts with initial electrophilic acetylation of the activated aromatic ring and is followed by cyclization." With an appropriate leaving group in the /f-position (OMe. or other amines such as in the unsaturated carbonyl compound (e.g., 4) is formed. Other approaches to pyroncs include the self-condensation of protected //-hydroxy acrylates,intramolecular aldol reactions followed by condensation,thermal cycli-zations of unsaturated ()-chloro esters,and an iodo-cyclization-elimination sequence w th Michael acceptors.Oxymercuration of an unsaturated alcohol is an alternative cyclization approach to tetrahydropyrans. 

Alcohols are used in the synthesis of metsJ hydrides where metal alkoxides are intermediates. Isolation of hydridometal alkoxides from the oxidative addition of alcohols to metal centers is not common. Hydrocarbon solns of WjCNMej) and 2-propanol generate" NHMe and H at RT. The product results from alcoholysis, oxidative addition of i-PrOH and condensation to the tetramer, H W COPr-i),. Both Os3(CO),2 and Os3(NCMe)2(CO),g oxidatively add HOR (R = Me, Et), forming HOs3(OR)(CO)3q. Phenol adds to Ni[P(C H,)3]2 under mild conditions to yield HNi(OPh)[P(C,H )3]2. 

Phenylurethanes. Mix 100 mg of anhydrous alcohol (or phenol) and 100 mg of phenyl isocyanate (or a-naphthylurethane) and heat on the steam bath for 5 min. (If the unknown is a phenol add a drop of pyridine to the reaction mixture.) Cool, add about 1 mL of ligroin, heat to dissolve the product. 

Alcohols, as well as phenols, add to 3,4-dihydro-2//-pyran under acid catalysis giving 2-alkyl(aryl)-oxytetrahydropyrans 3 [16a]. These cyclic acetals are stable to base but prone to hydrolysis even with dilute acids. Thus, OH functions can be blocked reversibly (THP protecting group in organic synthesis) ... 

Analytical Techniques for the Determination of Phenolic Adds in Foods.328... 

Structure-Antioxidant Activity Relationship in Phenolic Adds.331... 

It appears that this partitioning system provides information on the compounds responsible for the effects described. The water extracts were the most inhibitory at both concentrations it contains phenolic adds and other soluble chemical compounds from the partitioning by organic solvents which are known allelopathic compounds. 

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