Anethol

BeschreibungAnethole is the main component of anise, star anise and fennel oils. It is used in the food and cosmetic industries, in bleaching colors photography and as an embedding material. Is mainly a cause of intolerance to toothpaste but may cause contact dermatitis in food handlers.

HistoryIn China, anise has been used as a traditional food spice and seasoning. In the anise plant, the main biological active ingredient is volatile oils such as trans-anethole. Till the end of last century, several methods to obtain the pure anethole have been developed, including:1. Cooling, crystallizing, and recrystallizing after the distillation of the anise oil.2. Heating p-methoxyphenyl crotonic acid at 220–240°C.3. Heating and dehydrating the derived product of anisaldehyde and C2H5MgX.4. Heating anisaldehyde together with propionic anhydride and sodium propionate.5. Adding concentrated hydrochloric acid and phosphoric acid to the mixture of anisole and propionaldehyde at 0°C and then heating the product with pyridine to remove hydrogen chloride.6. Prepare Grignard reagent using parabromoanisole, then react with allyl bromide to produce p-methoxyphenylpropylene, then heat with potassium hydroxide, and finally anethole was obtained after isomerization.7. Using crystalline ferric chloride to catalyze the reaction of p-propenyl phenol and methanol .Anethole is easily oxidized when exposed in the air, especially in the presence of heat, light, or catalyst . Therefore, in recent years, a series of studies have been carried out on the synthesis of its derivatives in order to obtain more active substances.

VerwendenPromote the white blood cells proliferation

synthetischeProduction. Anethole is isolated from anethole-rich essential oils as well as from sulfate turpentine oils or is synthesized starting from anisole.1) Anethole can be obtained from oils in which it occurs as a major component (main source is star anise oil) by distillation and/or crystallization. 2) A fraction of American sulfate turpentine oil (0.5% of the total) consists mainly of an azeotropic mixture of anethole and caryophyllene. (E)-Anethole can be isolated from this mixture by crystallization. 3) Another fraction of American sulfate turpentine oil (1% of the total) consists essentially of an azeotropic mixture of estragole (l-methoxy-4-allylbenzene, bp101.3 kPa 216°C) and α-terpineol. Treatment with potassium hydroxide yields a mixture of anethole isomers and -terpineol, which can be separated by fractional distillation.4) Synthesis from anisole and propionic acid derivatives. Anisole is converted into 4-methoxypropiophenone by Friedel–Crafts acylation with propionyl chloride or propionic anhydride. The ketone is hydrogenated to the corresponding alcohol with a copper chromite catalyst.The alcohol is dehydrated in the presence of acidic catalysts to a (Z)-/(E)-mixture of anetholes.