Reacting hydrogen with an acyl chloride in the presence of palladium produces these compounds in the Rosenmund reduction.
Four equivalents of pyrrole and four equivalents of these compounds react to form a porphyrin ring. In an IR spectra of these compounds, smaller peaks appear on the right shoulder of the C-H stretches, at around 2700 inverse centimeters. Reacting hydrogen with an acyl chloride in the presence of palladium produces these compounds in the Rosenmund reduction. One of them reacts with a lysine residue in opsin to form rhodopsin. A secondary alcohol is produced when one is reacted with a Grignard reagent. Glyoxal contains two of these functional groups, and a primary alcohol can be partially oxidized by PCC to one of them. For 10 points, name these compounds which, unlike related ketones, contain a terminal carbonyl group.
Four equivalents of pyrrole and four equivalents of these compounds react to form a porphyrin ring.
aldehyde [prompt on carbonyl]