Wurtz synthesis

The Wurtz synthesis is a method of producing alkanes by the reaction of all l 

This method was first carried out by Adolph Wurtz in 1885. 

In the Wurtz synthesis, a complex alkane is produced from smaller ones. Hence methane cannot be produced in this way. If different aUqd halides are used in the Wurtz synthesis, three different alkanes can be formed. For this reason, this method is more useful for alkanes which have even numbers of carbon atoms. 

Two different a%l halides produce three different alkanes. 

Which a%l halides should be used to obtain hexane by the Wurtz synthesis Explain. 

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A similar process may take place in the reduction of polar compounds with single bonds. A halogen, hydroxy, sulfhydryl or amino derivative by accepting an electron dissociates into a radical and an anion. In aprotic solvents the two radicals combine. In the case of halogen derivatives the result is Wurtz synthesis. In the presence of protons the anion is protonated and the radical accepts another electron to form an anion that after protonation gives a hydrocarbon or a product in which the substituent has been replaced by hydrogen. 

The familiar Wurtz synthesis of polysilanes from dichlorosilanes and alkali metal evidently does not involve free silylenes. See R. G. Jones, R. E. Benfield, R. H. Cragg, A. C. Swain and S. J. Webb, Macromolecules, 26, 4878 (1993). 

A long established method for the preparation of alkanes involves heating an alkyl halide with sodium metal (the Wurtz synthesis). 

Ultrasound activation accelerates the synthesis, probably by maintaining a clean surface on the sodium particles. This allows the Wurtz synthesis to be carried out at much lower temperature, in benzene, tetrahydrofuran (THF) or diethyl ether.14 The synthesis is also speeded by the addition of additives which complex alkali metal cations, that is 15-crown-5 ether.15... 

Polysilane copolymers that contain a limited amount of hydrogen can be obtained using the Wurtz synthesis (5.12). The isolation must however be carried out carefully under... 

There were two reasons why Colonius and I were favored to be the first to hit on this very simple reaction in 1930. First, it was just then that lithium was first used for certain technical applications (e.g., as an alloy component for bearing metals), and therefore became easily accessible at a tolerable price. Second, the experiments described under II above had induced us to study the kinetics of certain lithium alkyl reactions. From these we had found that ethyllithium and alkyl halides, especially chlorides, essentially do not react with each other. Therefore the course of our decisive experiments had been predictable (38). This impetus had been necessary to overcome the prejudice about the Wurtz synthesis originating from the textbooks. 

PBBs may be used as starting materials in the synthesis of biphenyl esters, in a modified WUrtz synthesis and as color activators in sensitizers also, to control the molecular weights of polymers, e.g., in polybutadienes. Other possible uses include wood preservation and as voltage stabilizers in electrical insulation (ref. 80, p. 438). 

Attempts to produce higher silicon hydrides from H3SiCl or H2SiCl2 by means of a Wurtz synthesis (with Na/K alloy or amalgam) were unsuccessful, SiH4 and yellow polymeric silicon hydrides being formed for the reasons mentioned above. 

Wurtz synthesis and similar coupling mechanisms have also been used in the preparation of higher silane derivates ... 

Kumada et al.359 prepared linear methylpolysilanes up to n = 12 by Wurtz synthesis from different chloromethyldisilanes and found by investigation of the physical constants that the melting points of the silanes up to n = 7 do not rise continuously but follow in a zigzag course since the polysilanes with an odd number of silicon atoms melt at a lower temperature, than those with an even number of silicon atoms, though this effect is less pronounced with higher n. 

The oldest known heterocycles are those containing oxygen as the hetero element. Kipping s work386) 382) with the first cyclosilanes (formed by a Wurtz synthesis from diphenyldichlorosilane) led to the discovery of two... 

Polymeric silicon alkyl compounds Polymeric compounds are often observed in the Wurtz synthesis of dihalodialkyl(aiyl)silanes with metals. The intermediate product is probably a dialkyl(aryl)silylene (see Chapter 7). A polymeric dimethylsilane was found by Burkhard68). A yellow polymeric (SiCH3) was isolated after pyrolysis of SiH4 with ethylene156). 

Of the other methods for preparing organosilicon compounds, the Grignard and direct methods have been selected for further consideration here. This is not to say that the Wurtz synthesis and the meta-thetical reactions of silicon tetrachloride with alkyls of zinc and mer-... 

Wurtz synthesis. The condensation reaction between two halides brought about by the action of metallic sodium, as in... 

The total number of carbon atoms in the reactants must be equal to number of carbon atoms in the product in a Wurtz synthesis. Hexane, contains 6... 

Wurtz synthesis Alkyl halides react with sodium in dry ether solution to give hydrocarbons. 

Dimethyl and diethyl sulfates have been widely employed in the synthesis of alkylbenzenes and alkylnaphthalenes from aryl- and benzyl-type organometallic reagents. The final methyl groups of isodu-rene and pseudocumene are introduced in this manner. The reaction is superior to the Wurtz synthesis (method 9) for the preparation of o- and -diethylbenzenes. n-Propylbenzene obtained from benzylmagnesium chloride and diethyl sulfate ° is contaminated with a "rearranged product, f -ethyltoluene. ... 

Wurtz Synthesis.—The introduction of carboxyl in place of a halogen in the ring may also be effected by the action of an ester of chlor formic acid and sodium. 

Muller, E., Roscheisen, G. A variation of the Wurtz synthesis. I. Catalyzed reactions of benzyl and allyl halides with alkali metals. Chem. 

Fittig s synthesis of the aromatic hydrocarbons is the analogue of Wurtz synthesis of the aliphatic hydrocarbons, e.g. ... 

NOTES.—(a) In carrying out the Wurtz synthesis the reaction is often brought about in a solvent the halide, or mixture of halides, is diluted with about twice its volume of ether which has been dried over sodium. The preparation described above should yield from 7 to 8 grams of the slightly impure hydrocarbon. 

Diethyl ether is also used both in the Wurtz synthesis and in the preparation of Grignard Reagents. 

Alternative approaches to synthesize 221 include the reaction of phenyllithium (222) with SiCl4 (yield 99%) (equation 104)132, or the reaction of 222 with triphenylsilane (223) (equation 105)133. A facile way for preparing e.g. triphenylsilane (223) is to react diphenylsilane (123) with 217 (equation 106)134. Analogously to the Wurtz synthesis, 221 can be obtained by the reaction of chlorobenzene, gaseous SiF4 and sodium at 150°C according to a US patent135. 

A Wurtz synthesis with halogenobenzene (224) and Me3SiCl affords the respective phenyltrimethylsilane (225) (equation 107a). This route can also be applied to halogeno-benzenes with substituents in ortho position as demonstrated by equation 107b136,... 

A well-established route to tetrakis(4-biphenylyl)silane (233) is the reaction of 4-bromobiphenyl (232) with SiCl4 and sodium (yield 90%) according to Wurtz synthesis (equation 112)141. 

Von Braun1051 prepared long-chain a ,co-dihaloalkanes from the corresponding bisphenyl ethers, which are accessible from aryl co-haloalkyl ethers by a Wurtz synthesis (a). 

Reaction of metal halides and organic halides with metallic sodium in a kind of Wurtz synthesis ... 

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