Organic Halides with the Metal

In both this and the previous method of preparation, low yields are often found, due to competitive coupling reactions or to further reactions such as the decomposition of the M— R], products. Also tire metal anions are strong nucleophiles and they may cause the or mic halides to undergo elimination reactions. Metal-acyl complexes are often by-products of the reaction of organic halides with the metal carbonyl anions they are formed by insertion reactions (see p. 258). Indeed, acyl halides may be used to give metal-acyl complexes which are dien decarbonylated either thermally or by photochemi techniques [. Some metal-aryl complexes which are... 

Organolithium compounds are often prepared by the reduction of organic halide with lithium metal. 

In 1901, Victor Grignard, prepared an organomagnesium halide by the reaction of an organic halide with magnesium metal in dry ether. 

Organic halides serve as effective precursors of organic radicals, and the reduction of organic halides with reactive metal cathodes leads to the formation of organometallic compounds [Eq. (5)]. For example, the reduction of alkyl halides with a Pb cathode results in the formation of R4Pb [24-28]. The reduction at a Hg cathode results in the formation of R2Hg [29-32]. Sn is also effective as a reactive cathode to give R4 n [33-35]. 

The reaction of organic halides with alkali metals RX + 2 M RM + MX... 

The chief contaminants of organoalkalis made from organic halides with alkali metals [Eq. (a)] are the alkali-metal halide and unreacted alkali metal. For such organoalkalis as n-pentylsodium, which is insoluble in all solvents with which it does not react, there is no known method of purification of the product made by Eq. (a). 

Oxidative addition to transition metal atoms is important in preparing novel organometallic compounds. Reactions of organic halides with the atoms are covered in 5.8.2.9.3. Other reactants are discussed here. 

Many additives have been investigated for promoting the direct reaction of organic halides with tin metal, but the reaction has limited use. Dimethyltin dichloride can be prepared from the reaction of methyl chloride with molten tin, but, in the laboratory, the reaction is used principally for preparing diallyl- or dibenzyl-tin dichlorides. The reaction between tin(ll) halides and organic halides to give organotin trihalides, similarly finds little practical application. 

Organomagnesiums are synthetic tools in organic and organometallic chemistry since the discovery that organomagnesium halides can be prepared from an organic halide with Mg metal in a basic, aprotic solvent such as EtjO ... 

An important development of iiie diffusion flame technique was introduced [33] in 1964 in which a collecting system for the removal of the alkali metal halide products was incorporated. The halide products are the result of the reaction of two separate organic halides with the chosen alkali metal and one of the organic halides is labelled with chlorine-36. This technique, which is of considerable potential, has received relatively little attention [34—37]. It has been extended to the case of two different halides that are not labelled, using a conductimetric analysis of the alkali metal halide mbctures [36]. 

When organozinc halides are synthesized in situ by the reaction of organic halides with zinc metal or the zinc-copper couple, DME or benzene-DMA can be used as the solvent. " In the case of organozinc halides prepared by transmetallation of... 

Organozinc compounds can be prepared by direct metallation of organic halides with zinc metal. The procedure makes the coupling reaction more convenient. A mixture of alkyl halide, acyl chloride, and zinc metal upon stirring in the presence of palladium catalyst at room temperature gives the desired ketone.f - " While direct metallation can be carried out efficiently when the zinc-copper couple is used in some cases, the presence of copper ion sometimes prevents the coupling reaction with acyl chloride.f ... 

Organolithium compounds are often prepared by the reduction of organic halides with lithium metal. These reductions are usually carried out in ether solvents, and since organolithium compounds are strong bases, care must be taken to exclude moisture. (Why ) The ethers most commonly used as solvents are diethyl ether and tetrahydrofu-ran. (Tetrahydrofuran is a cyclic ether.)... 

This section describes methods of nitrile synthesis which are true substitution reactions, such as the reaction of an organic halide with a metal cyanide, and... 

The reaction of an organic halide with a metal is an oxidation-reduction in which the metal is the reducing agent. As shown in the fohowing equahons for the reactions of methyl chloride with lithium and with magnesium, a single-electron transfer from the metal converts methyl chloride to a radical anion, which then dissociates to a methyl radical and chloride ion. Bond formahon between methyl radical and a metal species ( Li or Mg" ) follows. 

The polymerizations described in Figs. 9.9 and 9.11 use a metal-catalyzed cross-coupling technique that has been investigated extensively [67-73]. The reaction is believed to proceed by (1) oxidative addition of an organic halide with a metal-phosphine catalyst, (2) transmetalla-tion between the catalyst complex and a reactive organo-... 

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