D. Apiole
Synonym Dill; Dill apiole; Parsley comphor.
Chemical Structure 4,5-Dimethoxy-6-(2-propenyl)-1, 3-benzodioxole.
Occurrence It occurs abundantly in dill oil Anethum graveolus L., belonging to the natural order Umbelliferae. It is also found in the Parsley seed oil Petroselinum crispum (Mill.) Nym. (Family: Apiaceae). The volatile oil of Sassafras albidum (Nutt.) Nees (Family: Lauraceae) contains apiole.
Isolation It is obtained by chilling the volatile oil to a very low temperature in a deep-freezer and finally recrystallizing it either from ethanol or petroleum ether (mp 29.5°C).
Characteristic Features Apiole crystallises usually in the shape of long colourless needles with a faint specific odour of Parsley. Its physical parameters are: mp 29.5°C, bp 285°C; n17D 1.5305; d15151.1598. It is practically insoluble in water, but soluble in ethanol, ether and in fatty oils.
Apiole on boiling with alcoholic KOH undergoes isomerisation to yield isoapiole (mp 55-56°C) whereby the allyl group in the former gets isomerized to the propenyl function in the latter as given below:
Apiole on treatment with bromine yields a monobromide (mp 51°C), a dibromide (mp 75°C) and also a tribromide (mp 120°C) as depicted below:
On oxidation with KMnO4 both apiole and isoapiole yield the corresponding apioaldehyde and apiolic acid.
Identification
1. It may be identified by forming its bromoderivatives as stated above having a specific melting point.
2. It may also be identified by preparing its oxidative products with KMnO4, such as: opioaldeyde (mp 102°C) and apiolic acid (mp 173°C).
Uses
1. It exerts a synergistic activity with insecticides.
2. Dill is frequently employed as an aromatic stimulant, carminative and flavouring agent.
3. Dill oil is an important ingredient of ‘Gripe Water’ which is given to infants to relieve them from flatulence.
