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Визначення

Phenylethyl alcohol, or 2-phenylethanol, is an organic compound with the chemical formula C₈H₁₀O. It is a colorless liquid with a pleasant floral odor.

КВІТКОВИЙ СОЛОДКИЙ
2-Phenylethanol, Phenethyl alcohol, Phenethanol, Benzyl carbinol, β-Hydroxyethylbenzene, Benzeneethanol, PEA
Type
Складник
Olfactive family
Квіткові
Source
Mainly chemical synthesis; also extracted from rose petals
Chemical class
alcohol
Інструменти
Піраміда
ВВерхні ноти
СНоти серця
ББазові ноти
5/5Сила
Дуже висока
інтенсивність запаху

Запах

The odor of phenylethyl alcohol is soft, like roses. It is described as a mild, warm, rose, honey-like odor. Pure phenylethyl alcohol has an extremely mild roselike odor. Material of more than 99% purity varies in odor because of the impurities present. The odor is also described as pleasant and floral. The low end of its odor detection threshold is given as 7.02 ppm.

Докладно

Chemistry

The molecule of phenylethyl alcohol consists of a phenethyl group (C₆H₅CH₂CH₂–) attached to a hydroxyl group (–OH). It is optically inactive. It is slightly soluble in water, but miscible with most organic solvents. It is soluble in fixed oils and glycerol, and slightly soluble in mineral oil. Partial oxidation to phenylacetaldehyde makes it honey-like in consistency in the course of time. With anhydrous calcium chloride it forms a solid compound that can be used for its purification. Oxidation with chromic acid mixture yields phenylacetaldehyde and phenylacetic acid. Its taste is initially slightly bitter, then sweet and reminiscent of peach.

Occurrence

Phenylethyl alcohol is found in extracts of rose, carnation, hyacinth, Aleppo pine, orange blossom, ylang-ylang, geranium, neroli and champaca. It is also naturally present in plants such as roses, jasmine, buckwheat and tomato. It has been observed as a constituent of the leaf oil of Pinus halepensis, of rose oil and of neroli oil. In rose and neroli oils the alcohol appears also to be combined as an ester with benzoic acid and phenylacetic acid. Rosa centifolia absolute is composed of more than 50% phenylethyl alcohol. Rose oil contains only a small fraction of the phenylethyl alcohol found in the leaves, because of the alcohol's appreciable solubility in water. The larger part of the alcohol remains in the aqueous distillate. Bulgarian distilled rose oil is naturally low in phenylethanol, and Ukrainian or Russian rose oil is naturally high in phenylethanol.

It is also an autoantibiotic produced by the fungus Candida albicans. Various wild-type yeasts, including Saccharomyces cerevisiae, Kluyveromyces marxianus and Yarrowia lipolytica, can synthesize it de novo. Fusel alcohols like phenylethyl alcohol are grain fermentation byproducts, and therefore trace amounts are present in many alcoholic beverages.

Other uses

Phenylethyl alcohol is used as an additive in cigarettes. It is also used as a preservative in soaps due to its stability in basic conditions. Due to its antimicrobial characteristics, it is used in laundry and home care products. It is generally recognized as safe and used in the pharmaceutical industry, mainly as a preservative. As a pharmaceutical aid it acts as an antimicrobial. 2-Phenylethanol has been investigated as a potential postharvest biocontrol agent against gray mold in tomatoes.

Explore all seven extraits in the Discovery Set.

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Related: 2 Phenoxyethanol · Alba Rose · Benzophenone · Beta Damascenone · China Rose · Citronellyl Formate · Desert Rose · Dried Rose

Цікавий факт

The pure compound is difficult to crystallize because it tends to supercool to a glass. Natural 2-phenylethanol can cost 250 to 300 times more than the chemically synthesized compound. The compound also forms a number of azeotropes.

Отримання й хімія

Спосіб отримання

About 93% of the commercialized compound is obtained by chemical synthesis. The most common commercial route is the Friedel-Crafts reaction between benzene and ethylene oxide in the presence of aluminium trichloride. This alkylation of benzene with ethylene oxide takes place at temperatures lower than 25 °C. Hydrogenation of styrene oxide over Raney nickel also gives phenylethyl alcohol. In a Grignard route, chlorobenzene is converted to phenylmagnesium chloride, which reacts with ethylene oxide at 100 °C. It can also be made by reducing phenylacetic acid with sodium borohydride and iodine in THF. Natural 2-phenylethanol is extracted mainly from rose petals. For rose flavor, the petals are usually harvested by hand and distilled in the presence of water, which gives an aqueous phase and a lipophilic phase. The aqueous phase is the rose water, in which 2-phenylethanol is the main component, while the lipophilic phase is the essential oil, which also contains it. It can also be produced by biotransformation of L-phenylalanine into 2-phenylethanol via the Ehrlich pathway, a process observed in yeasts and bacteria. Phenylethyl alcohol can also be produced by biotransformation of L-phenylalanine using immobilized yeast Saccharomyces cerevisiae. Product made by this biotransformation can be considered natural. Biotechnological production is not yet attractive for industrial applications because of low titer and high production costs compared with the synthetic route.

Формула
C₈H₁₀O
CAS
60-12-8
Зовнішній вигляд
Colorless, viscous liquid
Сила запаху
Extremely mild
Синоніми
2-Phenylethanol, Phenethyl alcohol, Phenethanol, Benzyl carbinol, β-Hydroxyethylbenzene, Benzeneethanol, PEA
Статус IFRA
Див. примітку

No IFRA Standard for the material itself (51st Amendment)

Фізичні властивості
Температура кипіння
219–221 °C @ 760 mm Hg
Температура плавлення
-27 °C
Температура спалаху
96 °C (205 °F), closed cup
Відносна густина
1.017 to 1.019
Показник заломлення
1.5325 @ 20 °C

У парфумерії

Phenylethyl alcohol is a common ingredient in flavors and perfumery, particularly when the odor of rose is desired. It is a flavor compound with a rose-like scent, used in the cosmetics, perfume, home care and food industries. It is also used in the preparation of artificial volatile oils. Its use in perfumery is especially in rose perfumes. Its rose-like odor and antibacterial properties make it a high-value compound for the cosmetic, food and flavor industries.

Роль у формулі
01фірмова нота
02сполучний компонент
03формувач об’єму
Форми випуску
натуральний ізолят синтетична речовина

Див. також

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