Synthesis
Piperonyl alcohol (0.15 g, 1.00 mmol) was dissolved in EtOAc (7 mL, 0.14 M fifinal concentration), and 1-hydroxy-1,2,benziodoxol-3(1H)-one (IBX 0.84 g, 3.00 mmol) was added. The resulting suspension was immersed in an oil bath set to 80 °C and stirred vigorously open to the atmosphere. After 3.25 h (TLC monitoring), the reaction was cooled to room temperature and fifiltered through a medium glass frit. The fifilter cake was washed with 3 × 2 mL of EtOAc, and the combined fifiltrates were concentrated to yield 0.14 g (90%, > 95% pure by 1 H NMR) of piperonal as a waxy solid.
Reference: More, J. D.; Finney, N. S. Org. Lett. 2002, 4, 3001−3003.
Chemical Properties
Heliotropin occurs in a number of essential
oils, but only in low concentrations. It forms white crystals (mp 37°C) with a
sweet, floral, slightly spicy, heliotrope-like odor.
Chemical Properties
Piperonal has a sweet, flowery odor reminiscent of heliotrope and a bittersweet taste.
Chemical Properties
white crystalline solid
Occurrence
Reported found in the essential oils of Robinia pseudo-acacia and Eryngium poterium; in the oils of Spirea
ulmaria and of leaves of Doryphora sassafras; also reported found in Tahitian and Bourbon vanilla, camphor wood oil, violet flowers
concrete and absolute, burley tobacco, rabbiteye blueberry, melon, pepper, cooked chicken, sherry and dill.
Uses
Piperonal is used as fragrance and flavoring agent.
Uses
In perfumery, in cherry and vanilla flavors, in organic syntheses.
Uses
Piperonal is an impurity of Tadalafil (T004500). Tadalafil impurity A.
Definition
ChEBI: An arenecarbaldehyde that is 1,3-benzodioxole substituted by a formyl substituent at position 5. It has been isolated from Piper nigrum.
Preparation
Heliotropin is produced by two main routes:
1) From isosafrole: For many years, oxidative cleavage of isosafrole was the only
route applicable on an industrial scale. Isosafrole [120-58-1] is obtained by
isomerization from safrole [94-59-7], which can be isolated from (Chinese)
sassafras oil . Examples of oxidants that give good yields of
heliotropin are chromium(VI) salts, oxygen, and ozone.
This method is still used currently, but the destructive exploitation of sassafras
trees in Southeast Asia has led to a strong decline in the availability of
sassafras oil and thus of safrole/isosafrole.
2) From catechol: Several routes have recently been developed for the synthesis
of heliotropin from catechol. In one such route, catechol is converted into
3,4-dihydroxymandelic acid with glyoxylic acid in an alkaline medium in the
presence of aluminum oxide. 3,4-Dihydroxymandelic acid is oxidized to the
corresponding keto acid (e.g., with copper-(II) oxide), which is decarboxylated
to 3,4-dihydroxybenzaldehyde. The latter product is converted
into heliotropin, for example, by reactionwith methylene chloride in the presence
of quaternary ammonium salts.
In another route, catechol is first reacted with methylene chloride and converted
into 1,2-methylenedioxybenzene . Reaction with glyoxylic acid in
strongly acidic media yields 3,4-methylenedioxymandelic acid . Subsequent
oxidation and decarboxylation with nitric acid afford heliotropin.
Alternative routes that start from 1,2-methylenedioxybenzene and use
piperonyl chloride as intermediate have been described .
Aroma threshold values
Detection: 62 ppb to 1 ppm. Aroma characteristics at 1.0%: sweet, anise-like, almond vanilla, floral, black
cherry pit, berry raspberry, powdery coumarin-like with a hint of hay.
Taste threshold values
Taste characteristics at 10 to 50 ppm: ripe black cherry fleshy, ripe berry, sweet, macaroon, Jordan almond,
creamy vanilla, spicy cream soda, courmarin, slight floral with hay nuances.
General Description
Colorless lustrous crystals.
Air & Water Reactions
Slightly water soluble .
Reactivity Profile
Piperonyl aldehyde is an aldehyde. Aldehydes are frequently involved in self-condensation or polymerization reactions. These reactions are exothermic; they are often catalyzed by acid. Aldehydes are readily oxidized to give carboxylic acids. Flammable and/or toxic gases are generated by the combination of aldehydes with azo, diazo compounds, dithiocarbamates, nitrides, and strong reducing agents. Aldehydes can react with air to give first peroxo acids, and ultimately carboxylic acids. These autoxidation reactions are activated by light, catalyzed by salts of transition metals, and are autocatalytic (catalyzed by the products of the reaction). The addition of stabilizers (antioxidants) to shipments of aldehydes retards autoxidation. Piperonyl aldehyde is sensitive to light. Piperonyl aldehyde may react with oxidizing materials.
Fire Hazard
Flash point data for Piperonyl aldehyde are not available. Piperonyl aldehyde is probably combustible.
Flammability and Explosibility
Not classified
Safety Profile
Moderately toxic by
ingestion and intraperitoneal routes. Can
cause central nervous system depression. A
human skin irritant. Mutation data reported.
Combustible when exposed to heat or
flame; can react with oxidizing materials. See
also ALDEHYDES.
Synthesis
By the oxidation of isosafrole with potassium dichromate and sulfuric acid and subsequent steam distillation of piperonal
Metabolism
In the animal body heliotropin undergoes the expected metabolic reaction involving oxidation to the corresponding acid (Williams, 1959).
Purification Methods
Crystallise piperonal from aqueous 70% EtOH or EtOH/water. [Beilstein 19/4 V 225.]
