Organosodium reagents

Organolithium and organosodium reagents can also be used to prepare tetraorganotins ... 

Organosodium compounds,767 as initiators, 14 255-256 Organosodium reagents, in tetraorganotin preparation, 24 812... 

The synthesis of 2-methylbutanoic acid (Expt 5.129) is illustrative of the method. Other organometallic reagents undergo a similar carboxylation reaction, and examples of the use of organolithium and organosodium reagents are included in the section on the synthesis of aromatic carboxylic acids (Section 6.13.3, p. 1069). 

The acetylide anions discussed in Chapter 11 are another example of organometallic compounds. These reagents are prepared by an acid-base reaction of an alkyne with a base such as NaNH2 or NaH. We can think of these compounds as organosodium reagents. Because sodium is even more electropositive (less electronegative) than lithium, the C-Na bond of these organosodium compounds is best described as ionic, rather than polar covalent. 

Toluene. Lithiation of aromatic and alkylaromatic compounds is markedly catalyzed by chelating diamines. Toluene is metalated by organosodium reagents but is rather unreactive toward organolithium compounds in the absence of diamine catalysts. However in the presence... 

In the usual preparation the moles of sodium chloride, sodium isopropoxide, and organosodium reagent are 1.6, 1.0, and about 0.36, respectively. The last amount varies with the yield in metalating the olefin but cannot exceed 0.50. In the last two experiments with butene-1, however, the amounts of isopropoxide were reduced to... 

With less active components of the catalyst, the composition is more critical. Some early work (8) with butenylsodium showed that some compositions which were active initially lost all activity with age. The data in Table I show also that the ratio of trans-l, 4- to 1,2-polymerization was relatively low in the last test with butenylsodium, where the mole quantities of the organosodium reagent and isopropoxide were 0.77 and 0.45, respectively, instead of 0.48 and 0.90 in the most active preparation. 

Another familiar type of sodium displacement reaction is the cleavage of ethers. This reaction is not important as a synthetic method, but it is an important side reaction which must be considered whenever ethers are used as solvents for organosodium reactions. Aliphatic ethers are essentially unreactive toward metallic sodium at moderate temperatures, but many organosodium reagents, such as phenylsodium and amylsodium, are able to cleave them by an acid-base reaction ROCH2CH2R + R"Na -> RONa + CH2=CHR + R"H... 

---