Alkylsodiums

Ignites immediately in air. The tendency to ignition decreases with ascent of the homologous series of alkylsodiums. 

Alkylsodium and alkylpotassium compounds are highly reactive and are among the most powerful of bases => they react explosively with water and burst into flame when exposed to air. 

These catalysts require temperatures above 100° and usually 150-200° for reasonable rates. Alkylsodium compounds at their decomposition temperatures (50-90°) have also been used by Pines and Haag (9). Lithium reacted with ethylene diamine has also been reported by Reggel et al. (4) as a catalyst for this reaction. The homogeneous system thus formed seems to lower the temperature requirement to 100° (4), whereas the use of potassium amide in liquid ammonia requires 120° (S). Sodium reacted with ethylene diamine has been reported to be an ineffective catalyst (4)- The most active catalyst systems reported so far are high-surface alkali metals and activated-alumina supports. They are very effective at or near room temperature (10-12). 

The same difficulty also occurs in the preparation of alkylsodium compounds. The starting halide RX couples with RNa (to give R—R and NaX) or is converted to an alkene. These reactions appear to involve radical intermediates undergoing combination and disproportionation (Section 10-8C) ... 

The Vuitz or Wnrtz-Fittig synthesis is usually thought of as a coupling reaction of two molecules of a halide or different halides by metallic sodium. In the liquid phase, as the reaction is generally carried out, alkylsodium compounds are intermediates and the coupling stage or second step is comparable to the reactions discussed above. °... 

Via transmetallation (method 1) Metal-bismuth exchange reaction occurs between triarylbismuthine and alkyllithium or alkylsodium reagents. 

Q Although alkylsodium compounds react with diethyl eiher, orga nomagnesium halides (Grignard reagents) do not. Why is this ... 

The accompanying papers in this volume, the literature cited in them, and this paper discuss reasons for the enhanced reactivity of these complexes. Mechanistic discussion has been left to a minimum in this paper to emphasize preparative and synthetic aspects. (A useful analogy as to what these complexes can do or how they will react is to consider their behavior to be similar to hydrocarbon soluble alkylsodium compounds if they were to exist.)... 

Comparative investigations of alkylpotassiums and alkylsodiums as reagents for metalation of terminal olefins have been carried out by Broaddus.88... 

In the aliphatic series the results are useful only for linkage of two identical halides, i.e., when R = R the smooth course of the Fittig reaction (see below) depends on the facts that aromatic halides react much faster than alkyl halides with the metal and, further, that arylsodiums react faster than alkylsodiums with an alkyl halide (for justification of these statements see the elementary textbooks). 

The Wurtz reaction constitutes the direct coupling of the nucleophilic carbon of an alkylsodium compound and the electrophilic carbon in a haloalkane. It is an unselective reaction. There is no way to control it to prevent coupling of two like alkyl groups while attempting to couple two different ones. In other words, the reaction between chloroethane and 1-chloropropane gives a statistical mixture of butane (from two ethyls), pentane (from an ethyl and a propyl), and hexane (from two propyls). 

Alkylsodiums and alkylpotassiums are considerably more reactive and are less commonly used. Of particular importance are stabilized carbanions derived from deprotonation of C-H bonds adjacent to carbonyl groups such anions are often referred to as enolates because the negative charge is localized more on the carbonyl oxygen than on the carbanionic carbon ... 

Matson EM, Forrest WP, Fanwick PE, Bart SC. Use of alkylsodium reagents for the synthesis oftrivalent uranium alkyl complexes. Organometallics. 2012 31 4467-4473. 

It is also known that the butadiene-styrene copolymerization with alkylsodium in the presence or absence of polar modifiers give only randomized copolymers.31 Furthermore, the molecular weight of the copolymer is too low. As a result, the reaction does not produce a high quality elastomer. The situation is totally changed when n-butylsodium-crown ether system is used as a catalyst for the copolymerization of... 

Figure 1-2. Comparitive metalation potency of alkylmagnesium halides, alkyllithiums, alkylsodiums, and alkylpotassiums (including superbasic mixed-metal reagents) empty boxes mean practically no reaction, gray-screened boxes mean marginal or unselective metalation, and black boxes mean efficient metalation.

Alkyl chlorides are strikingly unreactive toward organoalkalis. At +25 C, 1-chlorobutane and -butyllithium, both 0.5 M, show half-survival periods that largely exceed 100 h, in paraffinic or aromatic hydrocarbons, and that still approximate 40 h in diethyl ether. This inertness is of course fortunate as it enables the efficacious preparation of alkyllithiums and alkylsodiums by allowing the reaction of alkyl halides with finely dispersed and hence activated metals to be executed in paraffinic media such as pentanes or hexanes. 

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