Williamson-type etherifications

Most chemists were more comfortable with speculations about movements of atoms than with flows of aether squirts. In particular, the idea of hydrogen atom mobility was to become a leading theme in late-nineteenth-century organic chemistry, based in the work of Williamson at midcentury. Williamson s investigations of etherification led him to a theory of the water "type" as well as to experimental proof that water is H20, not HO. Williamson clearly expressed the idea of chemical equilibrium as a balance between two sets of molecules in which some atoms or (uncharged) radicals may exist freely for short periods of time.43 In addition to its uncontestable central role in the "quiet revolution" of the 1850s,44 this was a paper that inspired both chemists and physicists to think about the "degree and kind of motion"45 of atoms within the molecule as well as the motion of the molecule as a whole. 

In conclusion, phase transfer catalyzed Williamson etherification and Wittig vinylation provided convenient methods for the synthesis of polyaromatics with terminal or pendant styrene-type vinyl groups. Both these polyaromatics appear to be a very promising class of thermally reactive oligomers which can be used to tailor the physical properties of the thermally obtained networks. Research is in progress in order to further elucidate the thermal polymerization mechanism and to exploit the thermodynamic reversibility of this curing reaction. 

Treatments based on condensation reactions (such as in the classical Williamson synthesis) produce the most stable cotton derivatives. On the other hand, treatments based on addition reactions (such as in the Michael reaction) yield cellulose ethers that are somewhat less stable. This lower level of stability is because of the equilibrium nature of the addition reaction. Typical examples of these two types of cellulose etherification are carboxymethyla-tion [9,329,330] and cyanoethylation [9,329,330,332], respectively, both of which proceed in the presence of alkali. 

But the situation with Wurtz, as with Kekule, was more complex and more interesting than that. This was the first paper in which Wurtz finally abandoned equivalent-weight formulas and adopted the barred C and O symbols that indicate atomic weights. He now clearly signaled his acceptance of the theory of polyatomic radicals, which he referred to by that name. Kekule s "extremely important theoretical article" of a few months earlier, and before that, the etherification project of Williamson, "whose work has had such a large part in the development of this theory," had led (he wrote) to an important new interpretation of types, in which the linking ("lien") function of polyatomic radicals was placed in the foreground. ... 

R)- and (S)-l,l -bi-naphthyl-2,2 -di-[pflrfl-(frflMS-4-M-pentylcyclohexyl)phenoxy-l-hexyl]ether were synthesized through the Williamson etherification reactions of chiroptical ( )-(+)- and (S)-(—)-l,l -bi-2-naphthols, respectively, with phenylcyclohexyl (PCH) derivatives. The products will hereafter be abbreviated as R)- and (S)-PCH506-Binol (Scheme 3.1). The suhstituent is composed of PCH moiety, M-pentyl group (the number of carbon of 5), and hexamethylene chain linked with an ether-type oxygen atom, [-(CH2)sO-, 06], hence abbreviated as PCH506. 

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