Formula C8H6O3 Boiling point 263 °C | Density 1.34 g/cm³ Appearance Colorless crystals | |
 | ||
Similar Safrole, Isosafrole, Nitroethane | ||
Piperonal, also known as heliotropin, is an organic compound which is commonly found in fragrances and flavors. The molecule is structurally related to other aromatic aldehydes such as benzaldehyde and vanillin.
Contents
Natural occurrence
Piperonal naturally occurs in various plants. Examples include dill, vanilla, violet flowers, and black pepper.
Preparation
Piperonal can be prepared by oxidizing isosafrole or by using a multistep sequence from catechol or 1,2-methylenedioxybenzene. Synthesis from the latter chemical is accomplished through a condensation reaction with glyoxylic acid followed by cleaving the resulting α-hydroxy acid with an oxidizing agent. Synthesis from catechol requires an additional step, Williamson ether synthesis using dichloromethane.
Reactions
Piperonal, like all aldehydes, can be reduced to its alcohol (piperonyl alcohol) or oxidized to give its acid (piperonylic acid).
Piperonal can be used to synthesize:
- 3,4-methylenedioxyamphetamine (MDA), an illegal psychoactive drug reported to have entactogenic and stimulant properties.
- Piperonal is also used in the synthesis of tadalafil.
- Olmidine
- Stiripentol
- Heliotropin can be used to make piperonyl acetone. This in-turn is used to prepare Safrazine.
- L-DOPA synthesis:
- Reductive amination with piperazine would give Methylenedioxybenzylpiperazine.
- Nitroaldol reaction with nitromethane followed by reduction of the nitrostyrene gives 3,4-Methylenedioxyphenethylamine.
- Monomethylation of the above product gives Homarylamine.
- Hydrastinine is cyclization of the above product with formaldehyde.
- 1-(4-chlorobenzhydryl)-4-(3,4-methylenedioxybenzalamino)piperazine (Ex25 in Ropizine patent U.S. Patent 3,178,422).
Fragrance
Piperonal has a floral odor which is commonly described as being similar to that of vanillin or cherry. For this reason it commonly used in fragrances and artificial flavors. The compound was named Heliotropin after the 'cherry pie' notes found in the heliotrope flower's fragrance (even though the chemical is not present in the flower's true aroma). Perfumers began to use the fragrance for the first time by the early 1880s. It is commonly used to add vanilla or almond nuances, generally imparting balsamic, powdery, and floral aspects to a scent's character.
