Phenyl-oxygen bond

Oxygen-Phenyl Bond in Phenyl Benzoate. By using the new value for the enthalpy of formation of phenyl benzoate together with the most recent values (80 and —21 kcal. per mole, respectively) for the enthalpies of formation of the phenyl (3) and benzoate (11, 12) radicals, we obtain for the strength of the oxygen-phenyl bond in phenyl benzoate a value of... 

The reaction is somewhat less involved for 4-hydroxy-3-phenyl-coumarin tetra-0-acetyl-/3-D-glucopyranoside (LII).20 Since one of the products of methanolysis is methyl a-D-glucopyranoside (XLVIII), it is obvious that inversion of configuration has occurred, and that the oxygen-glucosyl bond was cleaved. These facts are rationalized if the controlling... 

Unsymmetrical alkyl phenyl tellurium derivatives were prepared in good yields from phenyl trimethylsilyl tellurium and epoxides, carboxylic acid esters, and linear or cyclic ethers under very mild conditions. In these reactions, which proceed in dichloromethane in the presence of a catalytic amount of zinc iodide, a carbon-oxygen single bond is cleaved. The highly nucleophilic benzenetellurolate binds to the carbon fragment, whereas the trimethylsilyl group becomes linked to the oxygen. 

Variation of X has little effect on the length of the monomer repeat, owing to the fact that the terminal oxygen of the urethane group is almost colinear with the N-C (phenyl) bond. 

The contribution from XC would make the Ph—O bond stronger owing to increased resonance and thus increase its stretching frequency. The frequencies of the oxygen-phenyl stretching mode are given in Table 15.2. 

The [2+2] cycloaddition of isocyanates across metal/oxygen double bonds is also observed. For example, complexed molybdenum oxide reacts with phenyl isocyanate to give the [2+2] cycloadduct 147. ... 

We could cease trying to understand the nature of the benzoyloxy radical in M-B and P-B and assume only that its spin is near the original site of the carbonyl oxygen and that it has the observed g tensor. This might result from some unanticipated motion or distortion of the radical. If we then risk supposing that one of the benzoyloxy radicals of B-B has these same properties, we may determine the g tensor and spin location of the other. The same is true of B-B. In either instemce one of two plausible interpretations is incorrect. Either 1) the second radical has the same anomalous properties as the first and has its carboxyl group twisted about the C-phenyl bond, or 2) the second radical is in a II electronic state and is essentially unmoved in B-B but twisted by 11 about the C-phenyl bond in B-B. ... 

The migratory aptitude decreases from p-nitrophenyl over phenyl and / -tolyl to /j-anisyl. ° This substituent effect argues in favor of a two-step mechanism, i.e., nucleophilic addition of the metalated a-carbon onto the aryl //7TO-position to give the bridged intermediate 354 and subsequent scission of the oxygen-aryl bond (Scheme 1-277). 

The extent of decarboxylation primarily depends on temperature, pressure, and the stabihty of the incipient R- radical. The more stable the R- radical, the faster and more extensive the decarboxylation. With many diacyl peroxides, decarboxylation and oxygen—oxygen bond scission occur simultaneously in the transition state. Acyloxy radicals are known to form initially only from diacetyl peroxide and from dibenzoyl peroxides (because of the relative instabihties of the corresponding methyl and phenyl radicals formed upon decarboxylation). Diacyl peroxides derived from non-a-branched carboxyhc acids, eg, dilauroyl peroxide, may also initially form acyloxy radical pairs however, these acyloxy radicals decarboxylate very rapidly and the initiating radicals are expected to be alkyl radicals. Diacyl peroxides are also susceptible to induced decompositions ... 

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