3-CARENE Usage And Synthesis

3-carene is the main volatile component of many plant essential oils, including turpentine, pepper oil, angelica oil, etc. Its molecular formula is C10H16. It is a monoterpene and appears as a colorless liquid. Due to the pine wood-like aroma of 3-carene itself, it is widely used in edible flavorings. According to the "National Food Safety Standard - Standard for the Use of Food Additives" (GB2760-2014), 3-carene is a permitted synthetic flavoring for food use. In addition, 3-carene can be used in pesticides, drugs and cosmetics, and is also one of the important raw materials in chemicals such as plasticizers.

The chemical properties of 3-carene

3-carene, due to the presence of three important functional groups - the ternary ring, the six-membered ring, and the double bond within the ring - in its molecular structure, has highly reactive chemical properties and is prone to oxidation, reduction, isomerization, rearrangement, addition, halogenation, sulfonation and other reactions. It is one of the important natural chemical raw materials. It can be used as raw material to synthesize many valuable chemicals such as fragrances, plasticizers, non-infectious solvents, and intermediates for pharmaceuticals and pesticides. Many of these products have been widely applied in various industries.

The biological activity and application of 3-carene

The volatile substance 3-carene exerts different active effects in different plants. In some precious Chinese medicinal materials, it is a drug active ingredient; in fragrant plants, it is a flavoring active ingredient, such as the aroma component of flowers and fruits; and in some other plants, it is an insect repellent or pheromone aggregation active ingredient. The use of 3-carene as the active ingredient and its direct utilization in plant form has been well demonstrated in traditional Chinese herbal medicines, but the more important forms of utilization are natural essential oils (in the form of mixtures) or isolated compounds.

The application of 3-carene in cosmetics

GB 2760-2007 Hygienic Standard for Food Additives stipulates that 3-carene itself can be directly used as a natural food flavoring (No. 11761; FEMA 3821. Chemists from Poland and India have synthesized a series of high-value-added fragrances using 3-carene as the raw material. For instance, 4-carenone obtained by treating 3-carene with zinc salt is a pleasant herbal fragrance that can be used as an aromatic agent, or the isopromenthol acetate produced by further reaction can be used as an additive in toothpaste. In addition, 3-carene was acetylated to obtain 4-acetyl-carene, which has the herbal aroma characteristics of Perilla fruticosa. The American IFF Company named it Carenko for sale.

The application of 3-carene in drugs

Lena et al. conducted an experiment on the sensitivity of guinea pig lungs to 3-carene. The results showed that when the mass concentration of 3-carene in the air was 600 mg/m ³, it could cause bronchial constriction. Agneta et al. 's research indicates that 3-carene can irritate the skin and mucous membranes, leading to allergic dermatitis or chronic lung function impairment. As an active ingredient, 3-carene is often used for anti-inflammatory and antibacterial purposes. For instance, the essential oil of P montezumae Lamb containing 3-carene, the volatile oil of Heracleum hemsleyanum, and AsarumsieboldiiMiq containing 3-carene have anti-inflammatory effects. It has a good antibacterial effect through the synergistic action of 3-carene and other monoterpenoids it contains.

The application of 3-carene in pesticides

3-carene is often directly used as an active ingredient in chemoattractants. For example, 3-carene can be used as a repellent component for adult Longhorn beetles to inhibit the egg-laying behavior of female longhorn beetles. The attraction and capture effect of the red borer beetle obtained in the forest by using a core made of 3-carene as a single component. According to Cheng et al., 3-carene has both repelling and killing effects on Aedes albopictus.

In addition to direct application, 3-carene can be used as a raw material to synthesize biologically active pesticide intermediates. For instance, chiral 1R-trans pyrethroid pesticides can be synthesized from 3-carene, as well as new photosensitizers with optical activity such as pyrethroids and porphyrin-like macrocyclic metal complexes.

3-carene resources 

3-carene is widely present in the roots, stems, leaves, flowers and fruits of plants. It is mostly a trace or small amount component and is a rare spice resource. According to research reports, the main source of natural 3-crene is turpentine from some special tree species, such as Pinus ponderosa and Pinus banksiana Lamb, followed by some essential oils of Chinese herbal medicines. Such as Folium Artemisiae Argyi essential oil, Piper nigrumL. Essential oil, etc.

Turpentine is the main source of 3-carene. Research has found that the content of 3-carene in turpentine of Indian longleaf pine (Pinuslongifolia) can reach 55%, while that in turpentine of European red pine (Pimus sylvestris Linn) is 40% to 45%. The content of turpentine in Pinusechinata is approximately 8%, that in the resin of Pinussibirica duour. In Xinjiang is 7.2%, and that in the resin of Pinus sylvestris var:mongolia is 12.1% The content of pine resin in Pinus densata is 15.0%.

Herbaceous resources, as one of the important components of floral and fruity aromas, 3-carene exists in many flowering and fruity plants. Wang Huajun et al. extracted the volatile components from the fruit of the white ivory mango by simultaneous distillation extraction method and measured the content of 3-carene to be 7.06% by GC-MS combined method. The volatile oil of white pepper, known as the "King of Tropical Spices", contains 3-carene as the main component, with a content of 28.0%. The content of 3-carene, the main component in the volatile oil of Murraya koenigiiL leaves, is 17.01%. Wei Wang et al. measured the content of the main component 3-carene in mugwort essential oil to be 2.64% by GC-MS combined method. Deng Qinying et al. reported that the water-soluble aroma component 3-carene in the steam distillation effluent of the peel of commercially available Shatian pomelo (Citrusmaxima (Burm.)Mer: cv. ShatianYu) was determined by GC-MS combined technology. Jokingtzu by microwave and distillation extraction and GC - MS stab identified different leaf prickly ash (ZanthoxylumovalifoliumWightvar. Spinifolium (Rehd. Et Wlis.) Huang) terpene class volatile components also contains 3 - carene.

3-carene exists as an active ingredient in some Chinese herbal medicines. For example, Ligusticum sinense Oliv, which has sedative and analgesic effects Such as Ligusticum brachylobum Franch., Liguaticum wallichii, Ligusticum oliverianum de Boiss. And Ligusticum All acuminatum (Franch.) contain 3-carene, among which the content of 3-carene is the highest in Ligusticum fasciata. The volatile oil of the dried rhizome of Kaempferiae galangal Linn., which has the effects of digestion and pain relief, the volatile oil of pepper, which can be used as a food flavoring agent, and the volatile oil of the flower of CarumcarviL, which has the effect of relieving asthma, all contain 3-carene. 3-carene was also detected in Amomum villosum Lour., one of the "Four Great Southern Medicines".

As a spice resource, 3-carene plays an irreplaceable role. Bergamot (CitrusmedicaL. Var: sarcodactylis) is valuable spices and important Chinese medicinal materials resources, the main ingredient in its fruit leaf essential oils contain a 3-9.30% carene. 3-carene is one of the main components in the Angelica oil obtained from the roots of Levisticum officinale Lovage, with a content of 3% to 12%.

In addition, the volatile oil of the fruit of Alpinia galangal L contains 3-carene. The roots of Petasites japonicus (Sieb. et Zucc. Maxim.), fennel seeds, star anise (Iliciuimn verum Hook.f.), and basil (Ocimum basilicum Linn., the bark of Abies nephrolepis (Trautv.) Maxim., juniper berries (Juniperus rigida Sieb.et Zucc), Nardostachys jatamanse DC., and wood seeds Litseapungens Hemsl.) All essential oils contain 3-carene.

Refining of 3-carene

Due to the fact that the content of 3-carene in turpentine is 20% to 25% and that of β -pinene is 30% to 40%, and secondly, because the boiling points of 3-carene and β -pinene differ slightly (169℃ to 170℃ for 3-carene and 165℃ to 166℃ for β -pinene), in order to achieve efficient separation of the two through a single distillation method, multiple repeated distillations are required. Considering that β -pinene and 3-carene have different reactivity, β -pinene can be converted into other compounds with significantly different boiling points from 3-carene through chemical reactions without affecting 3-carene. The resulting mixture can then be easily distilled to obtain high-purity 3-carene.