Phenol salts

The aromatic ring of alkylphenols imparts an acidic character to the hydroxyl group the piC of unhindered alkylphenols is 10—11 (2). Alkylphenols unsubstituted in the ortho position dissolve in aqueous caustic. As the carbon number of the alkyl chain increases, the solubihty of the alkah phenolate salt in water decreases, but aqueous caustic extractions of alkylphenols from an organic solution can be accomphshed at elevated temperatures. Bulky ortho substituents reduce the solubihty of the alkah phenolate in water. The term cryptophenol has been used to describe this phenomenon. A 35% solution of potassium hydroxide in methanol (Qaisen s alkah) dissolves such hindered phenols (3). 

Hydroxy group containing tertiary amines are also used because they become incorporated into the polymer stmcture, which eliminates odor formation ia the foam (3). Delayed-action or heat-activated catalysts are of particular interest ia molded foam appHcations. These catalysts show low activity at room temperature but become active when the exotherm builds up. In addition to the phenol salt of DBU (4), benzoic acid salts of Dabco are also used (5). 

However, many salts such as the hydroquinone or biphenol salt are so insoluble diat they do not work well by this procedure. Furthermore, a stoichiometric amount of base used for die reaction is critical to obtain high-molecular-weight polymers. Moreover, die sd ong base may undesirably hydrolyze the dihalides to afford deactivated diphenolates, which upset the stoichiometry. Clendining et al. reported that potassium carbonate or bicarbonate could be used in these reactions instead of corresponding hydroxides.60 McGrath and co-workers were the first to systematically study die use of the weak base K2C03 instead of a strong base to obtain phenolate salts.8,61,62 Potassium carbonate was found to be better than... 

The Ullman reaction has long been known as a method for the synthesis of aromatic ethers by the reaction of a phenol with an aromatic halide in the presence of a copper compound as a catalyst. It is a variation on the nucleophilic substitution reaction since a phenolic salt reacts with the halide. Nonactivated aromatic halides can be used in the synthesis of poly(arylene edier)s, dius providing a way of obtaining structures not available by the conventional nucleophilic route. The ease of halogen displacement was found to be the reverse of that observed for activated nucleophilic substitution reaction, that is, I > Br > Cl F. The polymerizations are conducted in benzophenone with a cuprous chloride-pyridine complex as a catalyst. Bromine compounds are the favored reactants.53,124 127 Poly(arylene ether)s have been prepared by Ullman coupling of bisphenols and... 

Polymers of vinyl phenol are obtained by hydrolyzing polyacetoxystyrene [286,287]. The respective phenol salts can be used. The demulsifier is applicable to oil-in-water emulsions and does not require the use of zinc or other heavy metals. Therefore it does not cause the environmental problems inherent in such metals. 

TV",TV-dimethyl formamide phenols, salts and sulphonamides azo violet thymol blue... 

Figure 4.1 Synthesis of salicylic acid from phenol salt.

The cleavage products of several sulfonates are utilized on an industrial scale (Fig. 3). The fusion of aromatic sulfonates with sodium hydroxide [1310-73-2] and other caustic alkalies produces phenolic salts (see Alkylphenols Phenol). Chlorinated aromatics are produced by treatment of an aromatic sulfonate with hydrochloric acid and sodium chlorate [7775-09-9]. Nitriles (qv) (see Supplement) can be produced by reaction of a sulfonate with a cyanide salt. Arenesulfonates can he converted to amines with the use of ammonia. This transformation is also rather facile using mono- and dialkylamines. 

Low molecular weight aromatic ethers have been prepared principally by the condensation of phenolate salts with aromatic halides 82). The Ullmann condensation (81), which employs copper or its salts as catalysts has been used in most cases in the laboratory. Recently a modification of the Ullmann condensation which consists of heating copper (1) oxide, the free phenol, and the aromatic halide in s-collidine has been reported (3). This method is recommended for alkali-sensitive aromatic compounds. In addition, reaction of phenolate salts with copper (1) oxide and the aromatic halide in boiling N,N-dimethyl formamide is described. When the halogen is activated by electronegative groups as in -chloroni-... 

Briner has studied this reaction further and showed that it was reversible (7, 8). The reaction proceeds in good yield for simple phenols without substituents in the o-positions and appears to be the basis also for a potential commercial synthesis of diphenyl ether (13). Low yields of aromatic ethers have also been obtained by pyrolysis of a variety of phenolate salts and esters (27, 41). 

The preparation of the related high molecular weight poly-1.4-phenylene sulfide has been accomplished by heating />-bromothio-phenolate salts in pyridine at 250° C (57). The commercially available polyethersulfones are reported to be prepared by condensation of 4.4 -dichlorodiphenyl sulfone with salts of biphenols in solvents such as dimethylsulfoxide at 150° C. The work of Bacon and Hill would suggest that both of these reactions might be carried out at considerably lower temperatures with copper (I) salts as catalysts. In addition, it has been demonstrated that copper (I) acetylides react quantitatively with aromatic iodides to yield tolanes (15, 77) therefore this reaction should also be the basis for a similar polymer forming reaction. 

The pKa is important since it affects the way certain phenolic compounds are extracted. If we consider having a mixture of phenols that range from weak acids to strong acids, the addition of sodium carbonate (Na2C03) or sodium bicarbonate (NaHC03) to the mixture will allow separation of these phenols. The weak base picks up the H from the strong acids or the more acidic phenols. This results in formation of phenolate salts of the phenols that are soluble in water. 

Since thiophenol is a moderately strong acid, it was expected that potassium and sodium salts of thiophenol would be present in the molten KOH-NaOH mixture. Both the sodium and potassium thio-phenolate salts were prepared in order to examine their thermal stability. Reaction products with the neat sodium salt were essentially the same as with thiophenol. Only diphenylsulfide (<1J) and diphenyldisulfide (1J-3.5J) were found, along with recovered starting material. Results using the neat potassium salt of thiophenol were completely different. The potassium salt underwent substantial decomposition (Equation 9), producing benzene (25 -3050 as the major identifiable product, 36 -38 CH2Cl 2-insoluble material, and 11 -15 recovered thiophenol (as unreacted potassium salt). 

In chloroform, no phenolate anion of 5 was detected even in the presence of excess piperidine as a base. Addition of crystalline lithium salts to this mixture gives rise to changes in absorption spectra, indicating the formation of the phenolate salt (Fig. 7). A dramatic color change from yellow to violet took place rapidly on addition of lithium salts, except for that with nitrate, fluoride, and sulfate counter anions. No tendency for the interaction was observed with any of the other 58 inorganic salts listed in Fig. 7. 

This rearrangement occurs only when a nonpolar solvent, e.g., benzene, is employed, which suggests that the initially formed phenolate salt of 12 is not sufficiently ionized to permit further... 

However, less than quantitative yields of reactions and difficulty in purification of the product hampered the practical use of this scheme. The same compounds can be prepared by nitro displacement of 3 or 4-nitrophthalimide with difunrtional phenol salts. In this reaction, the nitro group is displaced and leaves as a nitrite ion [27]. The products bis(etherimide)s are hydrolyzed to the tetracarboxylic acids which are in turn converted to the dianhydrides [28]. 

If a phenol salt is treated with an acid, the free phenol will separate out. This method presents the advantage that it may be applied to substances containing, in addition to the phenol-ether radical, a reducible carbonyl group, which, if treated with hydriodic add, would be changed. 

Phenolic salts lodosubgallate Salicylate Subgallate Tribromophenate Tannate Internal astringent and absorbent for the protection of the gastrointestinal membrane. Used externally as an antiseptic. Treatment for gastroenteritis, toxic diarrhea, dermatitis, and hemorrhoids... 

The thermodynamic values were calculated by the additive nature of the bonds and correspond to the hypotheses of a gas phase reaction. The software does not take account of phenol salts. 

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