"CHEMICAL DETERPENATION THROUGH THE CATALYTIC OXIDATION OF THE ESSENTIAL OILS OF CITRUS AND PRODUCT".

This invention concerns a chemical deterpenation the essential oils of citric fruits through a controlled catalytic oxidation by a suitable oxidizing agent in the presence of heterogeneous catalyst.

The present invention also reveals a modified essential oil derived from the above mentioned process. This oil contains residual limonene and a certain amount of oxygenated products obtained from limonene by its controlled oxidation, such as limonene epoxides, carveol, and carvone. Essential oils are usually responsible for most of the raw materials used for the production of perfumes and fragrances. Additionally, these oils are widely used in the products of personal hygiene, cleaners, cosmetics, food aromatizers, and flavor intensifiers. Despite the abundance of essential oils and their extensive use, Brazil is highly deficient monetarily in the import/export balance of such oils: crude oiles are exported at very low prices and the manufactured products derived from them are imported at extremely high prices.

Orange essential oils contain from 90 to 96 wt% of limonene, a monoterpenic chemical compound, which is highly reactive and easily decomposed under the action of light, humidity, and high temperatures. Limonene In addition to being responsible for the rapid degradation of oils - a low shelf life -also renders their low trade value. The United States, Uruguay, England, and Sweden are leading world producers of orange essential oils of low-limonene concentrations, which are also called deterpenated oils. Lack of deterpenation units has been pointed out as one of the factors of domestic low- price levels of the essential oil produced in Brazil, which is exported only as a crude product.

The deterpenated essential oil is produced by a physical removal of limonene which results in two fractions: a ready for commercialization concentrated oil fraction and a low-priced limonene fraction used as a solvent or in the production of polymers.

The technical state of the art shows some patents and scientific papers on the physical deterpenation of citrus essential oils, concentration of orange juice, and removal of undesired substances from citrus essential oils. a) EP1332201B1, US20040069713A1, WO0236720A1 Process for reducing the concentration of undesired compounds in a composition. Include processes for reducing the amounts of terpenic compounds in essential oils using column chromatography and concentrating the content of oxygenated compounds present in the oil. b) US4126709 Method for extracting carotenoid pigments from citrus oils. This invention describes the removal of steroids, coumarins and other undesired orange oil compounds using vacuum distillation techniques. c) US 20040031755A1 Extraction process using water. This invention describes an extraction method for oxygenated compounds of essential oils. The extraction method mentioned in this patent is comprised of a solvent removal of oxygenated compounds that are later concentrated by elution in absorbent material. The resulting product is a solution containing oxygenated compounds derived from the essential oil and washing organic solvent. d) WO9503380A1 Process for extracting essential oils from plants through cold maceration and cold deterpenating. This patent describes a process for obtaining concentrated essential oils from cold maceration of different plant species, which thus results in a more concentrated and chemically stable essential oil. e) IT1299580B1 Procedure for deterpenization of cold-pressed essential oils of citrus peels with super-critical carbon dioxide. This patent describes a process of deterpenation using a chromatographic technique of column separation and CO ₂ supercritical fluid as mobile phase. f) Citrus peel oil deterpenation with supercritical fluids. Diaz, S.;

Espinosa, S.; Brignole, E. A. PLAPIQUI (Universidad Nacional del Sur- CONICET), Bahia Blanca, Argent. Journal of Supercritical Fluids

(2005), 35(1), 49-61 e Supercritical fluid extraction for the removal of terpenes from citrus oil. Sato, M.; Goto, M.; Hirose, T. Dep. of

Appl. Chem., Kumamoto Univ., Japan. Editor(s): Shallcross, David C;

Paimin, Rohani; Prvcic, Leanne M. Value Adding through Solvent Extraction, [Papers presented at ISEC96], Melbourne, Mar. 19-23, 1996

(1996), 2 987-992.

These articles describe deterpenation using a chromatographic technique of column separation and CO ₂ supercritical fluid as mobile phase, g) Essential oil terpeneless by extraction using organic solvents or ionic liquids. Arce, Alberto; Marchiaro, Alicia; Rodriguez, Oscar;

Soto, Ana. Dept. of Chemical Engineering, University of Santiago de

Compostela, Santiago de Compostela, Spain. AIChE Journal (2006),

52(6), 2089-2097. This article describes a deterpenation technology using less toxic solvents and ionic liquids so as to render these solvents less aggressive to environment.

In summary, all publications found in the literature on the extraction of monoterpenic compounds, such as limonene, from the essential oils describe the processes consisting in physical removal procedures, such as distillations, chromatographic separations (mostly using supercritical CO ₂ as mobile phase), and adsortion/desortion of the oxygenated or hydrocarbon products.

All these processes allow to remove only small quantities of limonene from the citrus essential oil; therefore, a successive reprocessing of the concentrated oil is necessary to remove greater amounts of limonene and achieve deeper deterpenation.

The currently used deterpenation processes are called 5, 10, 15, and 20- fold processes. The numbers indicate the amounts of terpenes which could be removed by these processes. Using the 5-fold process, which is the most conventional one. the weight of the crude essential oil is reduced to a 1/5 of its original weight. This means that from 100 kg of the crude essential oil containing 96 wt% of limonene two new fractions are obtained; one of them

containing 80 kg of limonene and the other containing 16 kg of limonene and 4 kg of oxygenated products, i.e., 20 kg of concentrated oil containing 80 wt% of limonene can be obtained by the 5-fold process.

Detailed Description of the Invention The present invention is characterized by the process of the chemical deterpenation through the catalytic oxidation of the essential oils of citric fruits such as, nonlimiting, white grapefruit, red grapefruit, sweet orange (citrus sinensis (L.) Osbeck) known in Brazil as laranja doce, laranja-lima, laranja da Bahia, laranja da terra, laranja pera, laranja seleta, laranja china, laranja hamlin, laranja natal, laranja Valencia, laranja folha murcha, and lima da persia (citrus aurantifolia), lima de umbigo (citrus lima), laranja barao (citrus sinensis), and limao galego (citrus aurantifolia), limao tahiti (citrus aurantifolia), limao siciliano (citrus limon [L.J Burm.f.), limao cravo (citrus limonia [LJ Osbeck), tangerina cravo (citrus reticulata), tangerina ponca(citrus reticulata), tangerina morgote (citrus aurantium x reticulata), and also cidra (Citrus medica L).

The technology used for the invention differs from the conventional ones, since instead of separating the terpenic fraction, e.g. limonene, from the oxygenated compounds already present in the oil, limonene is converted by the controlled oxidation into oxygenated compounds which are more valuable and more chemically stable than limonene itself. The final product constitutes chemically modified oil containing oxygenated products and smaller amounts of limonene.

The process proposed in the present invention uses citric fruit essential oil as raw material, a solid catalyst doped with transition metal, oxidant and it is performed preferably in the absence of a solvent, the latter being a nonlimiting factor. The resulting product is described as a modified essential oil derived from citric fruit essential oil comprised of residual limonene and oxygenated products, such as: limonene epoxides, carveol, carvone, and some other minor products. This invention is characterized by the use of solid heterogeneous catalysts in the process of chemical deterpenation by oxidation. This catalyst can be supported, impregnated or anchored material or the material obtained

through the isomorphic substitution of ions in solid matrix. Catalyst may be used alone or in the combination with other catalysts.

The use of metal and semi-metal oxides - such as zirconium, alumina, silica, titanium, acid zeolites, basic zeolites and also phosphates, hydroxyapatites, carbonates, coal, polymeric materials, dendrimers which are nonlimiting - as solid matrices for incorporating the catalyst, used alone or in combination, is also a characteristic of the present patent.

Another feature of the present invention is the use of transition metals, such as cobalt, titanium, vanadium, chromium, manganese, iron, copper, molybdenum, tungsten, and rhenium, as catalysts used alone or in combination in chemical deterpenation through oxidation of citrus essential oil.

Use of oxidizers such as molecular oxygen, ozone, hydrogen peroxide, organic peroxides or atmospheric air used alone or in combination is also characteristic of this invention. The product obtained through the chemical deterpenation by catalytic oxidation of citrus essential oil described here shows features that make it a potential raw material for the production of fragrant compounds for cosmetics, cleaners and personal hygiene products, flavor intensifiers for beverages and other food products. The innovation present here is that the via the process described in this invention it is possible to deterpenate citric fruit essential oil by converting limonene into oxygenated compounds of greater economic and chemical interest.

The examples listed below make this invention better understandable. Example 1: Oxidation of citrus essential oil catalyzed by metal oxides under atmospheric pressure using oxigen as oxidant.

A suspension of the heterogeneous catalyst L/M _x N _y where M=Zr, Al,

Si ₁ Ti; N=O; x and y = 2 or 3; L= Co, Ti, V, Cr, Mn, Fe, Cu, Mo, W, Re; was put in contact with 100,00 ml_ of the essential oil of laranja pera (citrus sinensis) initially containing 96 wt% of limonene in a glass reactor coupled with an oxygen bubbler. The mixture was heated within a range of 25° to 120°C and mechanically stirred. After 24 hours, approximately 40% of limonene present in

the oil was converted into limonene-derived oxygenated products, such as carvone, carveol, limonene epoxides.

Example 2: Oxidation of citrus essential oil catalyzed by metal oxides under superatmospheric pressure using oxigen as oxidant. A suspension of the heterogeneous catalyst LVM _x Ny where M=Zr, Al,

Si,Ti; N=O; x and y = 2 or 3; L= Co, Ti, V, Cr, Mn, Fe, Cu, Mo, W, Re; was put in contact with 100,00 mL of the essential oil of laranja pera (citrus sinensis) initially containing 96 wt% of limonene in a stainless steel autoclave equipped with a sampling valve and pressure manometer. The reactor was pressurized at 1.1-50.0 atm with air or molecular oxygen. The mixture was heated within a range of 25°C to 120°C and mechanically stirred. After 24 hours, approximately 65% of limonene present in the oil was converted into limonene-derived oxygenated products, such as carvone, carveol, limonene epoxides.

Example 3: Oxidation of citrus essential oil catalyzed by metal oxides using hydrogen peroxide as oxidant

A suspension of the heterogeneous catalyst L/M _x N _y where M=Zr, Al, Si ₁ Ti; N=O; x and y = 2 or 3; L= Co, Ti, V, Cr, Mn, Fe, Cu, Mo, W, Re; was put in contact with 100,00 mL of the essential oil of laranja pera (citrus sinensis) initially containing 96 wt% of limonene and 40 ml of 35% hydrogen peroxide in a glass reactor. The mixture was heated within a range of 25° to120 °C and mechanically stirred. After 24 hours, approximately 50% of limonene present in the oil was converted into limonene-derived oxygenated products, such as carvone, carveol, limonene epoxides.

Example 4: Characterization of modified essential oil The chemically modified essential oil obtained through the processes described in examples 1 , 2 and 3 has its features better understood by means of a gas chromatography (GC) analysis.

Figures 1 and 2 represent chromatograms obtained using a 17B Shymadzu chromatograph equipped with a 3OM Carbowax capillary column and Fl detector using the following conditions: H ₂ as a carrier gas (72 mL/min), injector temperature of 28O ⁰ C, detector temperature of 25O ⁰ C, initial

temperature in the column of 80 ⁰ C for 3 minutes, heating rate of 10 ⁰ C per minute up to 22O ⁰ C and 5 minutes at 22O ⁰ C, column head pressure of 90 kpa.

The main chromatogram peak at 2.00 min corresponds to limonene. The other peaks correspond to limonene isomers and oxygenated derivatives of limonene, such as, nonlimiting, limonene epoxides at 5.46 min, carvone at 9.37 min., carveol at 10.59 min. The product is also characterized by the presence of GC peaks cited in Table 1 and shown in figures 1 and 2.

Table 1 :