Limonene concentration ( Limonene) in cosmetics does not exceed 0.01%, so it is mentioned as one of the last in the list of ingredients.

Properties of limonene used in cosmetics:

Aromatic . Limonene imparts a fresh, light citrus or pine scent to cosmetics and hygiene products.

Solvent . Limonene is an excellent fat dissolver, and therefore is used in the production of cosmetics as a harmless alternative to alcohols.

Disinfectant. Limonene effectively fights fungal and bacterial microorganisms, mold, mites, helping to cleanse the skin and protect cosmetics from spoilage.

Limonene is an effective repellent because it not only repels, but also kills many insects, which is why it is included in ointments and sprays that protect against insect bites.

What cosmetics contain limonene?

Face and body creams
Lotions
Tonics
Tanning products
Shampoos, conditioners
Decorative cosmetics
Shaving products
Soap, bubble bath, shower gel
Decorative cosmetics
Lipsticks, lip balms

The use of cosmetics with limonene is undesirable:

for hypersensitive skin
with a tendency to allergies, especially to citrus and pine components

What is Limonene found in cosmetics?

Limonene is a substance related to terpene hydrocarbons. It was first isolated from the essential oil of orange peels back in the mid-19th century. At first, scientists believed that limonene had many different isomer variants, since this fragrant element was found in the essential oils of bergamot, cumin, lemon, mint, parsley, fennel, pine and many other plants, and even gave these variants different names. But then they came to the conclusion that there are only two varieties of limonene - one is found in citrus oils and smells of lemony freshness, and the other, with the smell of pine needles, is extracted from turpentine and pine oils (by the way, the term “terpenes” comes from the Latin expression Oleum Terebinthinae, meaning "turpentine").

Limonene is a popular aromatic fragrance for cosmetics, perfumes, hygiene and detergents, and medicines. Despite its flavor variations, limonene is usually referred to as the isomer that smells like lemon.

Due to its degreasing properties, limonene is indispensable in nail polish removers and for removing grease from the skin of the hands. Taking into account modern trends in environmental friendliness, it is becoming very popular to use home care products that leave a fresh, natural citrus scent. And limonene also helps with this, especially since its aroma can create a good mood.

Where do you get limonene for cosmetics?

Limonene can be obtained naturally and synthetically. Since citrus essential oils can contain up to 90% limonene, it can be extracted using centrifugation and fractional steam distillation. However, on an industrial scale, limonene is most often obtained synthetically from geraniol by chemically acting on its hydrocarbon chain.

The result is a viscous, transparent, colorless liquid with a strong lemon odor, which is completely insoluble in water, but easily contacts ethanol.

Limonene raises concerns about allergenicity and carcinogenicity. However, studies have shown that limonene is no more likely to cause allergies than other flavorings, including natural citrus flavors.

As for carcinogenicity, according to the International Agency for Research on Cancer, limonene is classified as a substance from the stable safety zone and is not classified as a carcinogen. Moreover, research is underway on the positive effects of limonene on the body in certain types of tumors.

Limonene is a solvent that is used in 3D printing to remove HIPS supports. This substance can replace acetone and a number of other solvents. Limonene is produced on the basis of technical citrus oil, so it has a pleasant smell.

It is insoluble in water and non-toxic. In addition, the material is biodegradable and therefore environmentally friendly. This solvent can be used several times, that is, it is reusable.

Due to the fact that the liquid does not dissolve plastics such as ABS, PC, PLA, it is used when working with these types of filaments, and when printing HIPS is used for supports.

It is important to follow safety precautions when working with limonene. Concentrates of this substance may irritate the respiratory tract and mucous membranes. Be sure to use gloves and work only in a well-ventilated area. Vapors may cause headaches. The solvent should not be heated to speed up the dissolution process, as this increases the volatility of the material. In addition, the model can change color.

Olya Likhacheva

Beauty is like a precious stone: the simpler it is, the more precious it is:)

Content

You can often find cosmetic products, household chemicals, and insecticides with citrus scents on store shelves. This effect is achieved due to a special ingredient - d-limonene. The substance is a clear liquid extracted from the peel of citrus fruits. Due to its positive properties, it is widely used in industrial production. Although its classification as a carcinogenic and allergic agent remains controversial. Find out everything about the substance limonene - what it is, whether it is beneficial or harmful, where it is used.

Substance limonene

E. Wagner in 1895 established the structural structure of limonene, a hydrocarbon belonging to the group of terpenes, 1-methyl-4-isopropenylcyclohexene-1. This colorless substance exists in the form of two active isomers: the racemic mixture and the enantiomers. There are D-limonene (with a citrus odor) and L-limonene (with a pine odor). Other names for this substance: terpene carbon, lemon extract, terpene.

Where is it contained?

Answering the question: limonene - what is it, you should consider how this substance is extracted and where it is found. D-limonen is a component of citrus fruits responsible for the smell. Its concentration is especially high in the peel (of lemon, orange, lime, grapefruit), in juice with pulp and amounts to up to 90%. In addition, the terpene is contained in turpentine from pine resin (up to 5%) and oils:

celery up to 60%;
caraway seeds up to 40%;
essential (neroli, bergamot, fennel);

Lemon extract can be obtained naturally (by centrifugation and fractional steam distillation) and synthetically (from geraniol). The result is a clear, viscous liquid with a strong lemon smell. The substance turns out to be water-insoluble, but has good contact with ethanol.

Where is it used?

Terpene hydrocarbon is used as an aromatic fragrance in perfumes, cosmetics, detergents, cleaning products, hygiene products, and medicines. Included in shampoos, conditioners, and solvents. The substance has degreasing properties, so it is used in nail polish removers to remove grease from metal before painting. Limonene is a worthy replacement for toxic petroleum products and solvents such as toluene, acetone, methyl, benzene. Home care products based on it have a pleasant smell, are biodegradable, and environmentally friendly.

A patent has been protected in Russia for the use of a complex of oils containing d-limonene in the production of alcoholic beverages. As a result, alcoholic products have a tonic effect and do not contain the smell of “fumes”. Pharmacologists also have not ignored the terpene, which can reduce the hepatotoxicity of drugs such as phenacetin, paracetamol, and caffeine. For medicinal purposes, this substance is also used as:

rubbing;
baths;
ingestion;
spraying.

Limonene in cosmetics

Due to the fact that limonene is an excellent fat dissolver, terpene carbon acts as an alternative to unsafe alcohols in the production of cosmetic products. Lemon extract extends the shelf life of drugs due to its antibacterial properties, and also gives them light pine or citrus aromas and acts as a repellent.

Beneficial features

The concentration of lemon extract in cosmetics is insignificant (no more than 0.01%), so it is listed last in the list of ingredients. Terpene carbon has multifaceted properties:

	Description	Where is it contained?
degreasing	removing excess oil from the skin	cream, tonic, lotion, shampoo
antibacterial	disinfects staphylococci, streptococci, meningococci, tuberculosis bacilli; fights mold.	home care products
aromatization	gives a pleasant smell	fresheners, deodorants
repellent	Repels insects and small pests	means of protection against midges, mosquitoes, moths.

In what cosmetics is it found?

Limonene is used in many fields, especially in the production of cosmetic products, perfumes, and cleaning products. The substance gives a pleasant smell and taste. It is recommended to store products containing terpenes in a cool, dry place. These include:

Product type	Function of limonene in cosmetics
shower gel	antibacterial
toothpaste	aromatization
Eau de Toilette
air conditioner	refreshes, gives a pleasant smell
	disinfects and removes excess fat
	activates oxidative and reduction processes, brightens the skin

D-Limonene

Dietary supplement based on orange peel oil - d-limonene from Jarrow Formulas. The drug stimulates the detoxification of enzymes in the liver and improves immunity. The product is taken daily during or after meals, 1 capsule. If an upset stomach occurs, it is better to discard the dietary supplement. You can buy D-Limonene in specialized departments, pharmacies and online stores. The price range for 60 capsules in Moscow and St. Petersburg is from 760-2000 rubles. By purchasing multiple packs you can save on cost.

Scientific and technological progress has led, on the one hand, to a significant improvement in the comfort of people's lives, and on the other hand, it has had a negative impact on the state of the environment and human health. As a result, a scientific direction called “green chemistry” arose, designed to make chemical production and its products as safe as possible for human health and the environment.

Nature has truly limitless resources of substances and compounds that can influence human life. Some of them become real sources of new ideas in the production of household and industrial chemicals, perfumery, cosmetics, food and pharmaceutical industries.

One such substance is d-limonene. This is a widespread terpene hydrocarbon, which is the main component of orange peel oil (up to 80-90%). It is also found in almost all citrus fruits and many other essential oils: lemon, tangerine, lime, grapefruit, bergamot, neroli, petitgrain, elemi, caraway, dill, fennel, parsley, erigeron, orthodone. d-Limonene is obtained by fractional distillation of mixtures of terpenes formed during their isolation from citrus essential oils. Currently, the annual production of d-limonene in the world reaches 70 thousand tons and continues to grow rapidly.

INCI: Limonene
CAS-No.: 5989-27-5
EINECS-No.: 5989-27-5
FEMA: 2633
Gross formula: C10H16
Molecular weight: 136.24
Boiling point: 175.5 °C
Density: 0.84 g/cm3 (at 20°C)
Appearance: Transparent, colorless liquid
with a pleasant citrus scent.
Soluble in alcohol, fatty and mineral oils, kerosene, acetone, dimethyl sulfoxide, diethyl ether, insoluble in water, propylene glycol, glycerin.

D-Limonene is widely used in production due to its diverse chemical properties and pleasant orange aroma:

an excellent solvent for fats, waxes, resins, plastics, petroleum products;

natural aromatic substance with a pleasant smell (for the production of perfume compositions, fragrances and food flavorings);

intermediate raw materials in chemical synthesis (terpinhydrate, terpineol, carvone, flotation reagents);

repellent;

antioxidant;

disinfectant;

skin lightening agent. d-Limonene can be used in its pure form, mixes well with other solvents and can be easily emulsified to produce water-soluble cleaning products.

d-Limonene is used in a wide variety of industries due to its diverse properties. It is included in many perfume products, shampoos, detergents and cleaning products, solvents - in everyday life and in production. It probably has no competitor when it comes to removing chewing gum marks or stickers from metal, wood or plastic surfaces. d-Limonene is used for degreasing metal before industrial painting, in household chemicals, for example, for cleaning wooden surfaces, and for removing grease from the skin of hands. It is an excellent environmentally friendly alternative to toxic and dangerous solvents and petroleum products such as: acetone, benzene, butyl cellosolve, toluene, trichlorethylene, xylene, methyl ethyl ketone, white spirit, etc.

Cleaning products based on d-limonene have a natural citrus scent, leave behind a fresh smell and, importantly, are biodegradable. In addition to household chemicals, it is widely used in perfumes and cosmetics. The current trend of using environmentally friendly products is contributing to the growing popularity of natural citrus scents. It has long been recognized that the smell of citrus fruits is very useful for creating a good mood and generally has a calming effect on the nervous system.

The use of d-limonene as an insecticide is interesting. It appeared because Ohio University entomology professor Fred Hinck discovered poisons that were lethal to fleas in orange peels. “These may be the only natural insecticides available that kill adult insects, their larvae and eggs,” he says.

Russian scientists have protected a patent for the use in the alcoholic beverage industry of an additive to improve the quality of alcoholic beverages in the form of a complex of essential oils, which includes d-limonene. According to the authors, the use of such an additive makes it possible to obtain vodka with increased stimulating and tonic effects, without an unpleasant “fume” smell after consumption, reduces the severity of hangover syndrome and, in general, weakens the harmful effects of alcohol on the body.

With the help of d-limonene, domestic pharmacologists have developed a method for reducing the hepatotoxicity of drugs such as paracetamol, caffeine, phenacytine, which are metabolized in the human liver to active metabolites, i.e. substances that are easily processed by the liver. As a result of medical and biochemical studies, data have been obtained on the hormone-regulating effect of d-limonene, which promotes the detoxification of estrogens by inducing the synthesis of the corresponding enzymes in the liver. This suggests that this substance may be effective in the prevention and treatment of breast and other tissue cancers.

The tables below highlight several popular uses of d-limonene. Information on its recommended dosages can be used as a guide to develop effective mixtures.

Studies of d-limonene for carcinogenicity and genotoxicity have shown that it is located in the “sustainable safety zone”. Its effects are approximately equal to the effects of caffeic acid from daily coffee consumption. The International Agency for Research on Cancer (IARC) classifies d-limonene as class 3, which means it is not classified as a carcinogen.

Due to its unique properties, d-limonene has found wide application in various industries. Through the efforts of chemists, biologists, doctors and scientists of other specialties, the range of applications of this amazing natural substance will undoubtedly be expanded and our world around us will become more pleasant, harmonious and safe.

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1. General information
3. Obtaining limonene
4. Physical properties
5. Chemical properties
6. Uses of limonene

1. General information

Limonene belongs to the group of unsaponifiable lipids that do not hydrolyze in acidic and alkaline environments. They are usually divided into 2 large subclasses: steroids and terpenes. . Steroids are present primarily in animal tissues, while terpenes are present primarily in plant tissues. Steroids and terpenes are built from the same isoprene units and are classified as isoprenoids.

Terpenes include a group of compounds that includes both polyisoprene hydrocarbons with the general formula (C 5 H 8) n and their oxygen-containing derivatives - alcohols, aldehydes and ketones. The hydrocarbons themselves are called terpenes, and their derivatives are called terpenoids. The isoprene units in terpenes are connected in a head-to-tail fashion:

They can have an acyclic and cyclic structure. Terpenes containing two isoprene groups are called monoterpenes. Diterpenes, respectively, contain four isoprene groups, triterpenes - six isoprene groups, tetraterpenes - eight isoprene groups. If there are three isoprene groups, then these are sesquiterpenes. Terpenes can be mono-, bi-, or polycyclic.

Limonene is a hydrocarbon that is a typical representative of monocyclic terpenes. Exists in the form of two optically active forms - enantiomers of D-limonene (( R) - enantiomer) and L-limonene (( S) is an enantiomer) and as a racemic mixture, which was previously considered a single substance called dipentene. The structure of limonene was established by E.E. Wagner in 1895 (Fig. 1).

(1) (2)

Figure 1. Structural formulas of L-limonene (1) and D-limonene (2)

Systematic name of limonene:

1-methyl-4-isopropenylcyclohexene. Since the limonene molecule is based on the carbon skeleton of p-menthane, limonene is also called 1,8-n-menthadiene (Fig. 2)

Figure 2. Structural formula of para-menthane

Trivial names for limonene are R-limonene and S-limonene, dipentene (for a racemic mixture)

limonene monocyclic terpene synthetic

2. Natural Sources of Limonene

Terpenes are found in essential oils of plants (mint, lemon, lavender, geranium and others), resin of coniferous trees, and milky sap of rubber plants.

Limonene is found in many essential oils (citrus essential oils contain up to 90% d-limonene). Together with pinene, it is found in lemon oil, up to 60% in celery oil, and up to 40% in caraway oil. It is also found in almost all citrus fruits and many other essential oils: lemon, tangerine, lime, grapefruit, bergamot, neroli, petitgrain, elemi, caraway, dill, fennel, parsley, erigeron, orthodone. Turpentine from the resin of Scots pine Pinus silvestris contains 4-6% dipentene. Turpentine, a volatile product of the distillation of oleoresin, is a mixture of terpene hydrocarbons. Most of all it contains b-pinene - up to 70%. In addition, turpentine contains the monocyclic terpenes β-pinene, limonene and carene, as well as small amounts of other terpenes.

3. Obtaining limonene

Synthetic limonene is produced in several ways. From isoprene as a result of the reaction of diene synthesis when heated (Fig. 3):

Figure 3. Scheme for obtaining limonene (dipentene)

Another way to obtain synthetic limonene is the pyrolysis of b-pinene.

Dipentene was synthesized from terpin hydrate and b-terpineol by eliminating water using potassium bisulfate or from gamma-carboxypimelic acid using the Perkin Jr. method; this method is also a method for the synthesis of b-terpineol (Fig. 4):

Figure 4. Dipentene production scheme

Limonene from plant materials is obtained by fractional distillation of mixtures of terpenes formed during their isolation from citrus essential oils.

Limonene in vivo is formed from geranyl phosphate through cyclization of the intermediate carbocation (Fig. 5):

Figure 5. Scheme of limonene formation in vivo.

4. Physical properties

Limonene (1,8-n-menthadiene), gross formula: C 10 H 16, molecular weight 136.24, has the appearance of a colorless, volatile, water-insoluble liquid with a pleasant lemon odor. Well soluble in non-polar organic solvents: alcohol, fatty and mineral oils, kerosene, acetone, dimethyl sulfoxide, diethyl ether. It exists in the form of optical isomers, the physicochemical constants of which are almost the same: melting point: - 74.35 ° C, boiling point 175.5-176.5 ° C; density: 0.84 g/cm 3 (at 20°C); relative coefficient of refraction n D 20 1.4746; rotation of the plane of polarization [a] D 20 =±126.3°; steam pressure (20°C) 139.6 Pa; flash point 42°C, ignition temperature 237°C; LD 50 for (+)-limonene 5 g/kg (rats, orally).

5. Chemical properties

Limonene is an unsaturated hydrocarbon, therefore it has chemical properties characteristic of unsaturated hydrocarbons.

Limonene is easily oxidized in air; Carvone can be obtained by targeted oxidation at the allylic position of the cyclohexene ring.

However, in industry, carvone is synthesized from limonene by nitrosation with nitrosyl chloride, followed by hydrolysis of the resulting carvone oxime. From carvone, limonene can be obtained through dihydrocarveol (Fig. 6):

Figure 6. Transformation scheme l-limonene to carvone and carvone to d-limonene

(+) - Limonene and (-) - limonene are relatively stable under thermal influence: they do not transform into other hydrocarbons when heated to 250-400 ° C, but only gradually racemize, giving dipentene.

Cracking limonene and dipentene at 500-700°C (passing vapor over a hot metal surface) leads to isoprene.

Limonene and dipentene in the presence of mineral acids are hydrated to form terpineol and terpine hydrate, during catalytic hydrogenation they are converted into n-menthane, and during dehydrogenation into n-cymene.

Figure 7. Scheme of d-limonene conversion to n-cymene

Upon complete hydration of dipentene in an acidic medium, according to Markovnikov’s rule, a dihydric alcohol is formed terpin, a drug which in the form of a hydrate is used as an expectorant for chronic bronchitis.

Figure 5. Scheme of hydrogenation and hydration of limonene

6. Uses of limonene

Limonene is used in a wide variety of production areas due to its diverse properties. D-limonene (( R) - enantiomer) has a pronounced citrus odor and is used as a flavoring agent in perfumery and in the production of flavorings. Smell of L-limonene (( R) - enantiomer) resembles the smell of pine needles, this enantiomer is also used as a fragrance. It is included in many perfume products, shampoos, detergents and cleaning products, solvents - in everyday life and in production. d-Limonene is used for degreasing metal before industrial painting, in household chemicals, for example, for cleaning wooden surfaces, and for removing grease from the skin of hands. It is an excellent environmentally friendly alternative to toxic and dangerous solvents and petroleum products such as: acetone, benzene, butyl cellosolve, toluene, trichlorethylene, xylene, methyl ethyl ketone, white spirit, etc.

Cleaning products based on d-limonene have a natural citrus scent, leave behind a fresh smell and, importantly, are biodegradable. It has long been recognized that the smell of citrus fruits is very useful for creating a good mood and generally has a calming effect on the nervous system.

The mechanism of biological action of D-limonene is to inhibit the activation of procarcinogens on cytochrome P-450 and the ability of this substance to increase the level of reduced glutathione in the body, which is known to be involved in the conjugation of active products of procarcinogens. More detailed studies have shown that D-limomene is capable of inhibiting not all isoforms of liver cytochrome P-450, but only cytochromes P4501A1/2 and P4502E1, i.e. precisely those hemoprotein isoforms that take part in the biological activation of paracetamol to a hepatotoxic product in humans. That. combined use of paracetamol and D-limonene can significantly reduce the hepatotoxic properties of the analgesic. In addition to paracetamol, cytochromes P450A1A1/2 and P4502E1 activate to active hepatotoxic products such drugs as phenacetin, caffeine, chlorzoxazone, theophylline, quinoline, quinoxaline, antipyrine, isoniazid, halothane, etc., as well as some carcinogens (halogenated polyaromatics, polycyclic aromatic hydrocarbons , nitroso compounds), organic solvents (hydrocarbon tetrachloride, benzene, toluene, acetone, aniline, styrene), alcohols (ethanol, propanol, butanol, pentanol). The hepatotoxic effects of all these compounds can be blocked by D-limonene.

List of sources used

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2. Limonene. Material from Wikipedia - the free encyclopedia. URL: http://ru. wikipedia.org/wiki/limonene

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5. Sidorov, I.I. Technology of natural essential oils and synthetic fragrant substances / I.I. Sidorov, N.A. Turysheva, L.P. Faleeva, E.I. Yasyukevich. - M.: Light and food industry, 1984. - 368 p.

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