Sodium phenoxide formation

In order to rationalize the orr/zo-selectivity observed in the reaction of sodium phenoxide 1 with carbon dioxide, the formation of a complex 3 is assumed. By that complexation the carbon dioxide becomes polarized, and its electrophilic character is increased. Complex 3 is of suitable geometry for reaction with the activated ort/zo-carbon center " ... 

Finally,- the alkali salts of phenol itself are more deeply coloured than is phenol. This fact cannot indeed be recognised subjectively, but investigation of the absorption of ultra-violet light demonstrates it. Thus it has been found that the absorption by sodium phenoxide much more nearly approaches the subjectively visible part of the spectrum than does that of the free phenol. The difference is so considerable that it provides also a satisfactory explanation of a subjectively perceptible deepening of colour from colourless to yellow. The colour of the salts of nitrophenols is therefore ascribed to the bathychromic (colour-deepening) efEect of salt-formation. 

These studies, which employed density functional theory (DFT) methods (B3LYP/LANL2DZ/Gaussian 98) proposed that the reactions of all alkali metal phenoxides with C02 followed a similar ground mechanism that comprised three intermediates and three transition states. In step 1, C02 must first be activated by an alkali metal phenoxide. In the case of the sodium phenoxide [24a], C02 can only attack at the polarized O-Na bond to form a Ph0Na/C02 complex as the first intermediate (structure 4). The calculation definitely rules out a direct C-C bond formation at the aromatic ring. 

Aromatic and aliphatic amino ethers have been synthesized by this method. An example of the formation of a cyano ether is the preparation of p-cyano benzyl methyl ether from the substituted benzyl bromide and sodium methoxide (84%). Also, certain aryloxyacetonitriles, AtOCHjCN, are made by the condensation of chloroacetonitrile with sodium phenoxides in a solution of methyl ethyl ketone containing a small amount of sodium iodide (70-80%). Aromatic nitro ethers, like o- and p-nitrodiphenyl ether, have been prepared by the Ullmann procedure (84%). The synthesis of alkyl p-nitrophenyl ethers has also been accomplished with good yields (55-92%). ... 

An alkaline catalyst like NaOH is used, with formaldehyde to phenol ratio varied from 1 1 to 3 1 (usually 1.8-2.4 ) for particle boards. Apart from catalyzing the hydroxymethylation of phenol, NaOH also serves to provide the required water solubility of the resin, even at a high molecular weight, through the formation of sodium phenoxides. Furthermore, it accelerates the curing of the resin. 

Aryl ethers. Pd-mediated C-O bond formation ameliorates the undesirable feature of the Ullmann method employing stoichiometric quantities of copper salts. Electron-deficient ArBr and electron-rich ArONa are suitable reaction partners. Electron-poor phosphine ligands improve the yields of the displacement reaction between aryl bromides and sodium phenoxides. 

Reaction of 2,3-dimethyl-1,3-butadiene with methyl acetoacetate is carried out with PdCl2 as a catalyst in the presence of sodium phenoxide. When triphenylphos-phine is employed, a 1 2 adduct is obtained. On the other hand, the use of 3-methyl-l-phenyl-A3-phospholene (168) at 100 °C causes formation of a 1 1 adduct to give... 

Fletcher and coworkers170-172 found that phenyl and methyl j8-D-ribofuranoside (1,2-trans) are obtained by treatment of 2,3,5-tri-O-benzoyl-D-ribofuranosyl bromide with sodium phenoxide and meth-oxide, respectively, whereas favored formation of /3-D-arabinofurano-... 

Polyethylene glycols (PEGs) can also be used as the catalyst in SLPTC. Chu [207] reported the kinetics for etherification of sodium phenoxide with benzyl bromide using quaternary ammonium salts and PEG as the catalyst in SLPTC. When PEG is used as the catalyst, formation of the complex PEG-Na PhO mainly occurs at the solid-liquid interface. The phenoxide anion carried by PEG can dissolve much more than its original... 

Equation (a) Phenol first undergoes dissolution in sodium hydroxide solution to result into the formation of sodium phenoxide, which on being subjected to benzoylation yields phenyl benzoate. 

Hydrolysis of Chlorobenzene (Dow Process). In this process chlorobenzene is heated at 350 °C (under high pressure) with aqueous sodium hydroxide. The reaction produces sodium phenoxide, which, on addification, yields phenol. The mechanism for the reaction probably involves the formation of benzyne (Section 21.1 IB). 

The original conditions employed by Kolbe involved the formation of sodium phenoxide through evaporation of a molar equivalent mixture of phenol and aqueous sodium hydroxide. The hygroscopic sodium phenoxide is then heated at 180 °C while a stream of carbon dioxide is passed over the molten salt. The mixture is then heated at 220-250 °C to give the dianion of salicylic acid along with carbon dioxide and phenol, both of which distill away from the reaction mixture. Under these conditions, only a 50% theoretical yield of salicylic acid can be realized and often less is isolated. 

Radical-cations may also be involved in the formation of phenyl esters from aromatic carboxylic acids and benzene in the presence of xenon difluoride, and can apparently be detected by e.s.r. spectroscopy during the reaction of iViV-dimethylaniline with perfluoropiperidine. The last reagent gives a low yield of o- and p-fluorophenol in the ratio 3.5 1 in its reaction with sodium phenoxide, and the predominance of ortho substitution is ascribed to a cage mechanism of the type shown in (3). However, towards 2,4,6-tri-t-butylphenoxyl radicals the piperidine acts as a source of fluorine atoms to give the dienone (4). ... 

Scheme 8.45. An example of the Reimer-Heman reaction. Dichlorocarbene is known to be generated from the reaction of trichloromethane (chloroform, HCClj) with, for example, aqueous sodium hydroxide. Introduction of sodium phenoxide solution results in the formation of orfho-hydroxybenzaldehyde. Substitution via either carbene insertion or electrophiUc addition resnlts.

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