cis-Anethol

Description

Anethole 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.

Chemical properties

White crystals; sweet taste; odor of oil of anise. Affected by light. Soluble in 8 vol- umes of 80% alcohol, 1 volume of 90% alcohol; almost immiscible with water.

Chemical properties

Anethole occurs both as its (Z)-[25679-28-1] and (E)-[4180-23-8] isomers in nature; however, (E)-anethole is always the main isomer. Anethole occurs in anise oil (80–90%), star anise oil (>90%), and fennel oil (80%). (E)-Anethole forms colorless crystals (mp 21.5°C) with an anise-like odor and a sweet taste. Anethole is oxidized to anisaldehyde (e.g., with chromic acid); when hydrogenated, it is converted into l-methoxy-4-propylbenzene.

Physical properties

Appearance: this compound shows a colorless or light-yellow liquid appearance. Melting point: 20–21?°C. Solubility: dissolve in chloroform and ether in unlimited amount; soluble in benzene, ethyl acetate, acetone, carbon disulfide, petroleum ether, and alcohol; insoluble in water. It has a sweet smell.

History

In 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.

The Uses of cis-Anethol

Promote the white blood cells proliferation

Definition

ChEBI: A monomethoxybenzene that is methoxybenzene substituted by a prop-1-en-1-yl group at position 4.

Preparation

Production. 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, bp_{101.3 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.

General Description

White crystals or a liquid. Odor of anise oil and a sweet taste.

Air & Water Reactions

Slightly water soluble .

Reactivity Profile

Protect from light .

Health Hazard

ACUTE/CHRONIC HAZARDS: Toxic.

Fire Hazard

cis-Anethol is combustible.

Contact allergens

Anethole is the main component of anise, star anise, and fennel oils. It is used in perfumes, food and cosmetic industries (toothpastes), bleaching colors, and photography, and as an embedding material.

Pharmacology

Anethole is the main ingredient in star anise oil and possesses a variety of pharmacological effects.
1. Increasing the white blood cellular activity. Some agents such as Shengbaining and Shengxuening, whose main active ingredients were extracted from the star anise, can promote mature white blood cells in the bone marrow to spread into the surrounding blood. Due to the body’s own feedback, mature and release speed of bone marrow cells were accelerated. It can also keep bone marrow cells’ activity, enhancing the white blood cells (especially granulocytes).
2. Bacteriostatic effect. Star anise oil shows antibacterial effects in a variety of strains including Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Aspergillus niger, Aspergillus flavus, Penicillium citrinum, yeast, Shigella, diphtheria bacillus, and Salmonella typhi. The results laid a theoretical foundation for the development and utilization of novel plant-derived antifungal propenylbenzene derivatives.
3. Antiviral effects . Star anise oil can act on different acyclovir-susceptible and acyclovir-resistant herpes simplex virus type 1 (HSV-1) strains.
4. Other effects. Anethole can improve the activity of anticholinesterase . It shows significant inhibitory effect against acetylcholinesterase and butyrylcholinesterase, and the IC50 value was 39.89±0.32?μg/mL and 75.35±1.47?μg/mL, while the value for star anise oil was 36.00±0.44?μg/mL and 70.65±0.96?μg/ mL, respectively. It has also been reported that anethole has an antioxidant effect.
Through structural transformation, a variety of compounds can be prepared from anethole. Anisaldehyde, produced by the oxidation reaction, was widely used in the preparation of flavors for its lasting aroma. On the other hand, it can also be used as the intermediate during the preparation of drugs such as amoxicillin.

Clinical Use

As a drug, anethole is mainly used for leukopenia caused by tumor chemotherapy.

Safety Profile

Poison by ingestion. Questionable carcinogen with experimental tumorigenic data. Combustible liquid. When heated to decomposition it emits acrid smoke and irritating fumes. See also ETHERS.