Gattermann reaction, aldehyde synthesis

Crafts alkylation and acylation (Section 22-4E and 22-4F), the Gattermann-Koch reaction for preparation of aldehydes from arenes and carbon monoxide (Section 22-4F), and the Kolbe-Schmitt, Reimer-Tiemann, and Gattermann reactions for synthesis of acids and aldehydes from arenols (Section 26-1E). 

REACTION ALDEHYDE SYNTHESIS — GATTERMANN-KOCH Example p-Tolylaldehyde from Toluene and Carbon Monoxide1... 

The Gattermann-Koch reaction can be carried out under two major types of conditions i.e. at atmospheric pressure where CU2CI2 is necessary as a promoter or complexing agent and secondly at high-pressure where the presence of CU2CI2 is not necessary. The Gattermann-Koch aldehyde synthesis is a suitable method for the preparation of simple aromatic aldehydes such as benzaldehyde and tolualdehyde. Formylation of ortho and... 

Gabriel synthesis Gattermaim aldehyde reaction Gattermann reaction Gattermann-Kocll reaction Gomberg-Hey reaction Grignard reaction... 

The Gattermann-Koch reaction when appHed to alkenes or alkanes gives ketones or acids but not aldehydes. However, the Vilsmeier aldehyde synthesis can be appHed to aUphatic compounds. For example, 1,2-diaLkoxyethylenes react with /V-methy1foTmani1ide and POCl to give alkoxymalondialdehydes ... 

The formylation of a phenol 1 with chloroform in alkaline solution is called the Reimer-Tiemann reaction. It leads preferentially to formation of an ortho-formylated phenol—e.g. salicylic aldehyde 2 —while with other formylation reactions, e.g. the Gattermann reaction, the corresponding /jara-formyl derivative is obtained as a major product. The Reimer-Tiemann reaction is mainly used for the synthesis of o-hydroxy aromatic aldehydes. 

The range of the reaction was extended by the elegant aldehyde synthesis of Gattermann and Koch. If a mixture of carbon monoxide and hydrogen chloride is allowed to act in the presence of aluminium chloride (and cuprous chloride) on toluene (benzene is less suitable), the reaction occurs which might he expected with formyl chloride if this substance were capable of existence. 

Gattermann aldehyde synthesis, 9, 2 Gattermann-Koch reaction, 5, 6 Germanes, addition to alkenes and alkynes, 13, 4 Glycals,... 

Gattermann Reaction (Gatterman Aldehyde Synthesis) /Gattermann Reagent... 

Phenolic ketones may be prepared by the Hoesch acylation reaction, which may be regarded as an extension of the Gattermann aldehyde synthesis (Section 6.10.1, p. 990). The procedure involves reaction of a nitrile with a phenol (or phenolic ether) in the presence of zinc chloride and hydrogen chloride best results are usually obtained with polyhydric phenols or their ethers, as for example in the preparation of phloroacetophenone (Expt 6.125). The formation of phenolic ketones by means of the Fries rearrangement of phenolic esters with aluminium chloride is discussed on p. 976. 

In a related reaction, the Gattermann aldehyde synthesis, the carbon monoxide of the previous reaction is replaced by hydrogen cyanide (Scheme 6.6). This reaction gives poor yields with benzene itself, but is successful with activated species such as aryl ethers and phenols. The reaction proceeds via an aryl imine and the mechanism is not dissimilar to that of the Vilsmeier-Haack reaction. 

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