Sodium phenoxide tetrahydrofuran

The reaction between benzyl chloride and sodium phenoxide follows second-order kinetics in a variety of solvents the nature of the products, however, v tries considerably. (a) In dimethylformamide, dioxane, or tetrahydrofuran, reaction yields only benzyl phenyl ether. Show in detail the mechanism of this reaction. To what general class does it belong (b) In aqueous solution, the yield of ether is cut in half, and there is obtained, in addition, o- and p-benzylphenol. Show in detail the mechanism by which the latter products are formed. To what general class (or classes) does the reaction belong (c) What is a possible explanation for the difference between (a) and (b) Hint See Sec. 1.21.) (d) In methanol or ethanol, reaction occurs as in (a) in liquid phenol or 2,2,2-trifluoroethanol, reaction is as in (b). How can you account for these differences ... 

Hexaphenoxy cyclotriphosphazene can be made by refluxing a mixture of trimer chloride with sodium phenoxide in tetrahydrofuran solution (7.326). It is a very stable white crystalline solid, mp = 112°C, which is soluble in benzene and is highly resistant to hydrolytic degradation. Certain aUcoxy derivatives will rearrange themselves to cyclophosphazanes when heated (7.327) (Figure 7.8). 

Thus there are many examples of PEG acting as a PTC (refer also to other contributions to the Symposium). It is of interest to inquire as to the effectiveness of other polyethers. Yamazaki and coworkers have examined the effect of various polymeric additives on the reaction between sodium phenoxide and n-butyl bromide in dioxane. Poly(oxetane), poly(tetrahydrofuran), and poly(ethyl-vinylether) were found to be ineffective, while PEG gave a rate enhancement of approximately 100. Interestingly, polyvinylpyrrolidone of several molecular weights was even more effective than PEG. ... 

The phase transfer method has also been used in the preparation of a variety of phenolic ethers [5]. It is interesting that alkylation of phenoxide anions generally yield products of both C and 0-alkylation with one favored to a greater or lesser extent depending on solvent. Sodium 2-naphthoxide, for example, exclusively C-benzylates in such hydrogen bonding solvents as ethanol [6], whereas 0-alkylation is favored in tetrahydrofuran. As the size of the cation associated with 2-naphthoxide is increased (for example from Li" to R4N ), 0-alkylation tends to be favored. Consistent with these observations is the report that 2-naphthol 0-alkylates under phase transfer conditions [5]. The successful 0-alkylation of the isomeric nitrophenols and salicyl-aldehyde are also noteworthy. These observations are consistent with the view that... 

---