Leaf alcohol

Description

Leaf alcohol exists as a liquid at room temperature with a characteristic odor of green leaves. It is found in green tea, violet leaf oil, and many types of leaves, herbs, and grasses. Leaf alcohol finds applications in perfumery as floral fragrance. Leaf alcohol is also investigated for its antidiabetic activity.

Description

cis-3-Hexen-1-ol is a natural product that is present in the leaves of most plants. It exudes the strong aroma of freshly cut grass and leaves, which accounts for its trivial name, “leaf oil”. Its odor can be the downfall of the plants that produce it because the compound attracts predatory insects.
Because?cis-3-hexen-1-ol is found in a wide variety of fruits and vegetables (including carnation, grape, kiwi, corn, tomato, and tea), it is a valuable resource for imparting fruit and vegetable aromas to foods and for use in perfumes. But the compound is less expensive to manufacture than to extract from natural sources. The annual output of commercial?cis-3-hexen-1-ol is ≈30 t.
So what is the Halloween connection??cis-3-Hexen-1-ol is the?major aroma component of freshly cut pumpkins. Think about it as you start to carve your jack-o’-lantern this season. Happy Halloween!

Chemical properties

colourless liquid

Chemical properties

Leaf Alcohol is a colorless liquid with the characteristic odor of freshly cut grass. In small quantities, leaf alcohol occurs in the green parts of nearly all plants. The volatile flavor constituents of green tea contain up to 30%.
A stereospecific synthesis of (Z)-3-hexen-1-ol starts with the ethylation of sodium acetylide to 1-butyne, which is reacted with ethylene oxide to give 3-hexyn-1-ol. Selective hydrogenation of the triple bond in the presence of palladium catalysts yields (Z)-3-hexen-1-ol. Biotechnological processes have been developed for its synthesis as a natural flavor compound, for example.
Leaf alcohol is used to obtain natural green top notes in perfumes and flavors. In addition, it is the starting material for the synthesis of (2E,6Z)-2,6-nonadien-l-ol and (2E,6Z)-2,6-nonadien-l-al.

Chemical properties

cis-3-Hexen-l-ol has an intense, green odor, not as strong as the corresponding aldehyde and a characteristic herbaceous, leafy odor on dilution. This substance can be obtained through extraction from various essential oils and purified by reacting it to the corresponding phthalate or allophanate; it was synthesized by Ruzicka and Schinz, who also clarified its chemical structure; Stoll and Rouve reported on the most significant differences between the natural and the synthetic products.

Chemical properties

3-Hexen-1-ol has an intense, grassy-green odor, not as strong as the corresponding aldehyde, and a characteristic herbaceous, leafy odor on dilution.

Occurrence

Main constituent of the oil distilled from the infusion of fermented tea leaves. Reported found as the corresponding ester of phenylacetic acid in the oil of Japanese mint (Mentha arvensis); the volatile oil of Thea chinensis contains approximately 26 to 35% 3-hexen-1-ol, whereas larger amounts are reported in the oils of Morus bombysic, Robinia pseudacacia and Raphanus sativus. Probably occurring also in several green leaves and herbs; reported found in the fruit juices of raspberry, grapefruit and others. Also reported in over 200 foods including apple, apricot, banana, citrus peel oils and juices, berries, guava, mango, grapes, pineapple, cabbage, kohlrabi, celery, cucumber, lettuce, leek, peas, sauerkraut, tomato, ginger, peppermint oil, coconut oil, spearmint oil, mustard, parsley, breads, butter, fish, fish oil, cognac, brandy, cider, sherry, grape wines, tea, soybeans, avocado, olive, passion fruit, plum, rose apple, Malay apple, water apple (Syzigium spp.), beans, marjoram, starfruit, broccoli, pear and apple brandies, figs, brussels sprouts, radish, prickly pear, litchi, dill, lovage, pumpkin, corn oil, malt, laurel, kiwifruit and other sources

The Uses of Leaf alcohol

cis-3-Hexen-1-ol is a naturally occuring compound that has the smell of freshly cut grass and is used to obtain a тАЬgreenтАЭ taste/smell in certain flavours and fragrances.

Definition

ChEBI: A primary alcohol that consists of (3Z)-hex-3-ene substituted by a hydroxy group at position 1.

Preparation

By the reaction of butyne-1 with ethylene oxide and subsequent selective reduction to the eis isomer (Bedoukian, 1967).

Aroma threshold values

Detection: 70 ppb

Taste threshold values

Taste characteristics at 30 ppm: fresh, green, raw fruity with a pungent depth

General Description

cis-3-Hexen-1-ol is one of the key volatile constituents of green leaf volatiles(GLV) that can act as an attractant to various insects. It is emitted by green plants when they are physically damaged.

Flammability and Explosibility

Flammable

Synthesis

Extracted from various essential oils and purified by reacting it to the corresponding phthalate or allophanate; it was synthesized by Ruzi-ka and Schinz, who also clarified its chemical structure; Stoll and Rouve reported on the most significant differences between the natural and the synthetic products (Burdock, 1995)

References

[1] NPCS Board of Consultants & Engineers, Industrial Alcohol of Technology Handbook, 2010
[2] A. Shirwaikar, K. Rajendran and C. Kumar, Oral Antidiabetic Activity of Annona squamosa Leaf Alcohol Extract in NIDDM Rats, Pharmaceutical Biology, 2004, vol. 42, 30-35