Ethyl-metal compounds

Ziegler and collaborators 162, 283) succeeded in the electrolytic preparation of tetraethyllead, a process which is also suitable for obtaining other ethyl metal compounds. The electrolysis of alkali aluminum (or boron) tetraethyl with a lead anode and a mercury cathode yields at the anode a... 

From Metal Alkyls. For the synthesis of Pb(C2H5)4 from metal alkyls, lead(ll) compounds are usually used as starting materials rather than lead(IV) compounds. This is because of better availability and easier handling of the Pb" compounds and yields with Pb" and Pb compounds are at best similar. Al(C2H5)3 has been studied as an ethylating agent more extensively than any other ethyl metal compound. For a general review of the synthesis... 

Alkylation and arylation of organosilanes occur readily with alkyl and aryl alkaU metal compounds. Yields from these reactions are good but are iafluenced by steric requirements on both silane and metal compounds. There is Httie iaductive effect by the organic groups attached to siUcon, as measured by the yield of products (126,127). These reactions proceed more readily ia tetrahydrofuran and ethyl ether than ia ligroin or petroleum ether, where R and are alkyl or aryl and M is Li, Na, or K. 

Aluminum alkyls undergo many reactions that are typical of covalent metal compounds. Compounds containing methyl, ethyl, and propyl groups ignite spontaneously in air. The reactions with water take place with explosive violence when the alkyl groups contain four or fewer carbon atoms. 

Although a metal catalysed decomposition of ethyl diazoacetate was originally described by Silberrad and Roy in 19061, it was to be many years before the value of this type of process for cyclopropanation of alkenes using transition metal catalysts was widely appreciated and reliable, efficient methods were developed. By the early 1960s, the reaction had become important in organic synthesis. Various transition metal compounds have been screened for catalytic cyclopropanation. Copper, rhodium and palladium compounds have... 

Reaction XXIII. (b) Condensation of Esters other than Ethyl Formate, with certain Ketones under the influence of Sodium Ethylate, Metallic Sodium, or Sodamide (Claisen). (B., 22, 1009 23, R., 40 38, 695.)— This is a similar reaction to that discussed above, and is part of a general condensation undergone by esters with oxy compounds, other phases of which are discussed on pp. 142-150. 

A method of producing the sol is to hydrolyse reactive metal compounds, for example alkoxidcs, M(OR) , where M is a metal (e.g. Ce and other rare earths, Al, Ti, Zr, etc.) and R is an alkyl group (e.g. methyl, CH3, ethyl, C2H3, or propyl,... 

This dependence on the polarity of the environment is not experienced with free radical reactions in general, but it follows the same pattern as oxidation-reduction potentials of metal compounds in these solvents a striking example is the case FeCl4 /FeCl4 2 where a jump of half a volt occurs in a very narrow range of ethyl alcohol-water mixtures (22). 

Ethyl diazoacetate (228 mg, 2.0 mmol) was added at a controlled rate over a 6-8 h period to a stirred mixture of the alkene (20.0 mmol) or diene (10.0 mmol) and the catalyst (0.01 -0,02 mmol) under and ordinarily at 25 C. For copper(I) triflate catalyzed reactions with enol ethers, the diazo ester dissolved in the enol ether w as added to copper(II) triflate in EtjO in order to minimize polymerization of the enol ether. Alkenes were generally purified by distillation prior to their use. The initial solubility of the transition metal compound was dependent on the alkene employed, and, with the exception of Rhg(CO)jg, bis(acetylacetonato)copper(II), and copper bronze, homogeneous solutions were obtained prior to or immediately after the initial addition of ethyl diazoacetate. 1 h after addition was complete, EtjO was added, the resulting solution was washed twice with sat. aq NaHC03 dried (MgSOJ. EtjO and excess alkene were distilled under reduced pressure. The desired cyclopropanes were obtained either by fractional bulb-to-bulb distillation or by preparative GC (Table 8). 

Zinc alkides form addition-products with aldehydes and ketones, which on treatment with water, yield secondary and tertiary alcohols, respectively. In the reactions between organo-metallic compounds and substances which contain the carbonyl group (C = 0), the positive, metallic atom enters into combination with the negative oxygen atom, and the alkyl radical unites with carbon. The structure of the compound formed from zinc ethyl and acetyl chloride is an example —... 

It is interesting that ethane can be converted to propionic acid and its mixed anhydride and trifluoromethyl ethyl ketone under the action of hydrogen peroxide in trifluoroacetic anhydride at 80 °C in the absence of a metal compound [49], The addition of palladium trifluoroacetate resulted in simple oxidation to ethanol and acetaldehyde. 

In contrast to diazomethane, a-diazo- S-carbonyl and - S-phosphoryl compounds cannot be halogenated by the direct methods mentioned above, but the corresponding a-mercury-bis(a-diazo-yff-carbonyl) (9.4) or (a-diazo-a-silver-)ff-phosphoryl) derivatives (9.6) must be synthesized first. The metallated compounds 9.4 and 9.6 react with molecular bromine and iodine or with other halogenation reagents, like sulfuryl chloride or cyanogen chloride. The compounds 9.5 and 9.7 are obtained in a yield of 30-90% (Schollkopf et al., 1968, for ethyl diazoacetate Regitz et al., 1979c, for diazophosphoryl compounds). 

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