why formaldehydhe does not under go iodoform test?

where "R" can be a hydrogen atom or a hydrocarbon group (for example, an alkyl group).

If "R" is hydrogen, then we have the aldehyde ethanal, CH₃CHO.Ethanal is the only aldehyde to give the triiodomethane (iodoform) reaction. If "R"is a hydrocarbon group, then we have a ketone. Lots of ketones give this reaction, but those that do all have a methyl group on one side of the carbon-oxygen double bond. These are known as methyl ketones.Since formaldehyde(HCHO) does not have this group so it is negative for iodoform test.

Thanks & Regrds

Aarti Gupta

askiitians Faculty