Publisher Summary This chapter discusses the synthesis of organometallics by decarboxylation reactions The decarboxylation reactions of metal carboxylates are of increasing value in the synthesis of organometallic compounds The reverse reaction, for example, carbonation of Grignard and organolithium reagents, is a well-known source of carboxylic acids The mechanisms of thermally initiated decarboxylations giving organometallic compounds have generally not been studied in detail, and mechanistic conclusions have largely been derived from substituent or solvent effects A number of possible unimolecular mechanisms can be envisaged for decarboxylation ranging from one involving a free carbanion intermediate to one involving a free-carbonium ion intermediate Formation of organometallics by radical-initiated decarboxylation is largely restricted to the preparations of monoorganomercurials from mercuric carboxylates Thermal decarboxylation has proved useful in the preparation of a variety of trihalogenomethyl– and a few polyfluoroalkylorganometallics Applications of the decarboxylation of metal cyanoacetates are currently restricted to derivatives of tin, lead, and copper Studies of the thermal decarboxylation of phenylpropiolates of copper, tin, and lead parallel those of the corresponding cyanoacetate compounds Syntheses of aryl organometallics other than polyhalogenoaryls by thermal decarboxylation are comparatively rare The hemidecarboxylation of sodium phthalate on reaction with mercuric acetate in boiling water was the first reported thermal decarboxylation Successful syntheses involving radical initiated decarboxylation are mainly limited to monoorganomercurials, where the method has extensive uses Radical initiated decarboxylation appears to have considerable scope in organometallic synthesis, especially where the incoming radical is part of a coordinated ligand

The synthesis of organometallics by decarboxylation reactions

Microwave assisted synthesis of novel organomercurials in 'dry media'

New data on the methods of synthesis and practical applications of organic compounds of mercury are surveyed and treated systematically. The bibliography includes 180 references.

Advances in the methods of synthesis of organic compounds of mercury

Decarboxylation of mercuric pyridine-2,3-dicarboxylate in hot dimethyl sulfoxide or hexamethylphosphoramide gives a mixture of 2-carboxylatopyridin-3-ylmercury(II) (major product) and 3- carboxylatopyridin-2-ylmercury(II) (minor product). The mixture reacts ( i ) with acidified halide ions ( Cl - or I-) to yield a mixture of the corresponding carboxypyridinyl ( halogeno )mercury(II) derivatives, (ii) with tribromide ions to give the bromo ( carboxypyridinyl )mercury(ii) complexes, 3-bromopyridine-2-carboxylic acid, and 2-bromopyridine-3- carboxylic acid, and (iii) with iodide ions in hot aqueous acetic acid to yield bis (2-carboxypyridin-3-yl)mercury(II) hydrogen triiodomercurate (II). Solutions of the last compound in dimethyl sulfoxide deposit bis (2-carboxypyridin-3-yl)mercury(II). Reaction of pyridine-2,3-dicarboxylate ions with mercuric acetate in boiling aqueous acetic acid at pH 5.0-5.8 gives mercurated acetic acid as the sole organometallic product, and the reported1 decarboxylation yielding 3-carboxylatopyridin-2-ylmercury(II) is not observed.

GB Deacon

Papers

Organomercury compounds. XXVII: The synthesis and properties of some carboxylato- and carboxy-pyridinylmercurials