KR100674626B1 - Catalytic process for the preparation of isolongifolene - Google Patents

Abstract

The present invention relates to a method for producing a catalyst by using a nanocrystalline solid super acid to prepare isolongipolene. This production method is a method for the production of isolongipolene, which is a tricyclic sesquiterpene hydrocarbon, is environmentally friendly, is made by a single step, and is prepared by a solvent-free catalyst. More specifically, the present invention provides a method for isomerization of long organolene to isolong group pollen using nanocrystalline zirconia sulfide as a solid superacid catalyst.

Description

Catalytic process for the preparation of isolongifolene

The present invention relates to a method for producing a catalyst by using a nanocrystalline solid super acid to prepare isolongipolene. This production method is a method for the production of isolongipolene, which is a tricyclic sesquiterpene hydrocarbon, is environmentally friendly, is made by a single step, and is prepared by a solvent-free catalyst. More specifically, the present invention provides a method for isomerization of long organolene to isolong group pollen using nanocrystalline zirconia sulfide as a solid superacid catalyst.

Longipolene, C ₁₅ H ₂₄ (decahydro-4,8,8-trimethyl-9-methylene-1,4-methanoazulene), is present in about 5-7% of Indian terebin oil obtained from Chirpine (Pinus longifolia). . This is the most productive sesquiterpene hydrocarbon available anywhere in the world.

The economic use of such terpene hydrocarbons involves converting it to isolongipolene and its derivatives, an isomer product widely used in the fragrance industry due to the fragrance of trees and flowers. These acid catalyzed reactions of isomerized isolongopolene and hydroformylation products (2,2,7,7-tetramethyltricycloundec-5-ene) have wood odor and are used as fragrances in the pharmaceutical industry.

Such isomerized aromatic compounds are of commercial importance as fragrances in the pharmaceutical art. Currently, isolongopolene, C ₁₅ H ₂₄ , is mainly produced by rearrangement reactions of longopolenes involving many steps of catalysis by inorganic acids such as sulfuric acid / acetic acid. Current methods using inorganic acids are multi-step processes that produce a large amount of unwanted waste compounds as by-products, which wastes require further treatment before disposal.

Since dangerous inorganic acids are corrosive, irritating, and require more than stoichiometric amounts, using dangerous inorganic acids is not safe from a handling point of view. In addition, the isomerization products obtained using inorganic acids are colored due to the production of impurities that require further purification.

Therefore, there is a need for a research effort to prepare isolong groupene from long organolene to overcome the above disadvantages and to find a more environmentally friendly and safer catalyst.

Referring to Sobti, R. R and Dev, S. (Tetrahedron, Volume 26, 649, 1970), isolongipoleone synthesis from campene-1-carboxylic acid is disclosed using a multistep process. In addition to involving many steps, this method has disadvantages in that the byproduct C ₁₃ -keto acid is produced by the decomposition of isorongipolene, using reagents in stoichiometric amounts.

Prahlasd, J. R. et al. (Tetrahedron Letters, Volume 60, 417, 1964) reported the synthesis of isolongipolene by acid catalysis of longipolene using acid treated silica gel. This synthesis strategy has a major drawback in the stability of the catalysts used, since the acid is exuded from the silica gel with prolonged use.

Beyler, RE and Qurisson, G. (J. Org. Chem. Volume 30, 2838, 1965) reported the synthesis of isolongipolene by treating long gifolene with boron trifluoride etherate. . In a typical reaction, longipolene is added to sodium-dried ether, to which boron trifluoride etherate is added, and the mixture is refluxed over a vapor bath for 60 minutes. The resulting dark brown mixture is carefully added to excess potassium hydroxide and ice. The mixture is stirred for 90 minutes at ambient temperature, and by the end of it the ether phase turns to straw yellow. Separation and further extraction, followed by water washing, followed by evaporation of the ether yields a pale yellow isolongipolene. This route has disadvantages in that it is synthesized in multiple stages by isorongipolene using dangerous compounds such as KOH, BF ₃ , and sodium metal. Separating the product from the reaction mixture involves several chemical treatments and takes additional time before the product is obtained.

Bisarya SC et al. (Tetrahedron Letters Volume 28, 2323, 1969) reported that isolonggifolene was treated by treating longgifolene with amberlyst-15 (Rohm and Hass) or acid treated silica gel for 36 hours at 95 ° C. The method of synthesis was reported in the yield of%. This method is disadvantageous in that it uses not only the thermal stability but also the amber swell which is a swelling ion exchange resin when used for a long time. In addition, this method takes 36 hours to complete the reaction.

Ramesha A.R. (Organic Preparation Procedure International, Volume 31, 227, 1999) reported a method of isomerizing longipolin with 100% selectivity and 90% or more conversion using montmorillonite clay K10 at 120 ° C. However, this method is disadvantageous in that it uses natural clay which has a large number of impurities and which is difficult to recycle to have the necessary surface acidity. Moreover, the clays have low thermal stability and are inactivated by use, and the recyclability of the clay catalysts is unknown.

Kula J., and Masarweh A. (Flaovour and Fragrance Journal, Volume 13, 277, 1998) reported the acid catalyzed rearrangement of longipolene to isolongepolene using bromoacetic acid. This method has the disadvantage of using bromoacetic acid, which is a liquid that is not safe to handle for isomerization. It is also difficult to separate the product from the reaction mixture.

Nayak. U. R. and Dev S. (Tetrahederon, 8, 42, 1960) reported a process for preparing isolongipolene by hydrating longipolene with acetic acid and sulfuric acid in dioxane. 3-Sesquiterpene alcohol with isorongipene was obtained as a byproduct. Typically, 200 g of longipolene in 500 mL of acetic acid and 40 mL of 50% sulfuric acid were stirred with 475 mL of dioxane. The mixture was left at 22-24 ° C. for 60 hours, then warmed at 52 ° C. for 10 hours, and then poured into 60 mL of water. The aqueous layer was treated with ammonium sulfate and then extracted three times with 50 mL of petroleum ether. The combined organic layers were washed with water and dried to evaporate the solvent. This dried product contained about 66% isolongipolene. This method has the disadvantage of using many steps and many reagents that are dangerous and toxic. This method also has problems in discarding the reagents used.

Wang, Hui et al., Jilin daxue Ziran Kexue Xuebao, 1, 88-90, 2001, (Chinese) reported the isolation and identification of isolongipolene along with other products derived from volatile oils in the stem and leaves of ginseng. . However, this method is time consuming and therefore does not meet many production needs, thus requiring the development of new synthetic routes.

Object of the present invention

An object of the present invention is to provide a method for producing isolong group pollen by the catalyst, overcoming the above disadvantages.

Another object of the present invention is to prepare isolong group styrene by isomerization of long group styrene.

It is a further object of the present invention to provide a process for isomerizing longipolin without solvents in a single step.

It is another object of the present invention to provide a process using nanocrystalline zirconia solid superacids as a catalyst.

It is a further object of the present invention to provide a method for isomerizing long organolene having a high conversion (> 90%) and having a selectivity to isolong organolene 100%.

It is a further object of the present invention to provide a process in which the conversion of the longigolene isomerization process and the selectivity to isolongipolene can be made high under atmospheric pressure and at an appropriate temperature.

It is yet another object of the present invention to provide a process in which isomerization of longopoles can be achieved by catalytic reactions having high atomic utilization and low E-factors.

Summary of the Invention

Therefore, the present invention

(i) hydrolyzing the zirconium alkoxide and sulphating with sulfuric acid to obtain zirconia sulfide;

(Ii) drying the zirconia sulfide and then calcining the dried zirconia sulfide;

(Iii) activating the dried sulfide zirconia catalyst obtained in step (ii);

(Iii) reacting longipolene with the activated catalyst obtained in step (iii) in a solvent-free medium with a ratio of catalyst to reactant in the range of 2-10% by weight to obtain an isomerization product. step;

(Iii) separating the isolongipolene, an isomerization product, from the reaction mixture;

(Iii) washing the catalyst to remove adhered material;

(Iii) drying the catalyst at 110 ° C. for 2-4 hours and then firing the air at 550 ° C. for 4-8 hours.

In one embodiment of the invention, the hydrolysis and sulfation in step (i) is carried out by a single step or two step sol-gel technique, at ambient temperature, in a medium selected from the group consisting of acidic, basic, or neutral media do.

In another embodiment of the invention, the zirconia sulfide is dried for 8-12 hours at a temperature of 110 ° C. and then calcined at 550 ° C. to 650 ° C. for 2-6 hours.

In another embodiment of the invention, the dried zirconia sulfide catalyst is activated prior to the reaction for 2-4 hours at a temperature in the range of 400-450 ° C.

In another embodiment of the present invention, the long gifolene reaction is carried out for 0.5 to 6 hours, under atmospheric pressure, while maintaining the reaction temperature in the range of 120 to 200 ℃.

In another embodiment of the present invention, the separation of the isomerization product isorongipolene is carried out by filtration.

In another embodiment of the invention, the catalyst is washed with ethyl acetate to remove the adhered material.

In another embodiment of the invention, the catalyst comprises (i) a crystallite size in the range of 10-100 nm; (Ii) a BET surface area of 80-120 m ² g ⁻¹ ; (Iii) nanocrystalline zirconia sulfide, which has a pore volume of 0.08-0.2 cm ³ g ^-1 and (iii) a pore size of 35-60 mm ³ , and is mainly tetragonal in crystalline state with catalytic activity.

Detailed description of the invention

Nano-crystalline zirconia with sulfate as the bidentate chelating species on the surface is used for the conversion by the catalyst at ambient temperature. Hydrolysis of zirconium alkoxides or zirconium salts can be in an acidic, basic, or neutral medium. Sulfation of zirconia with sulfuric acid can be accomplished by sol-gel techniques using a single step as well as two steps at ambient temperature. The solid acid catalyst contains sulfur in the range of 0.5 to 2.5% by weight after firing of the catalyst at a temperature of 600 ° C. The proportion of solid acid catalyst to reactant may vary from 2 to 10 wt%.

The temperature for the conversion by the catalyst may be in the range of 120 to 200 ℃, the reaction time may be 0.5 to 6 hours. The reaction may be carried out in a single step process, preferably under solvent free conditions.

In a typical method for preparing a catalyst, zirconium iso-propoxide is hydrolyzed with ZrO ₂ and sulfated with sulfuric acid to become zirconia sulfide. Hydrolysis and sulfation were carried out simultaneously during a single step process. In the two step process, hydrolysis was carried out in the first step and then sulfated in the second step. Hydrolysis was performed in basic and neutral media. In all cases the samples were dried overnight at 110 ° C. and then calcined at 550-650 ° C. for 2-6 hours. The catalyst thus obtained was cooled at ambient temperature. The activation of the catalyst thus prepared was carried out at 450 ° C. for 4 hours before the catalytic study.

Catalyst studies were carried out in a 50 mL capacity stirred tank reactor equipped with a temperature controller, a water circulator, a magnetic stirrer, and a water removal device. Typically, long gifolene (2 g) was placed in a 50 mL round bottom flask and activated catalyst (0.2 g) was added so that the ratio of long gifolene / catalyst was in the range of 2-10. Activation of the catalyst was carried out at 450 ℃ for 4 hours. The round bottom flask was placed in a condenser with constant temperature water. A moisture removal device was attached to the end of the condenser. The flask contents were continuously stirred using a magnetic stirrer. The flask was placed in an oil bath in which the temperature gradually increased in the range of 120-200 ° C., the desired reaction temperature. The contents of the flask were analyzed by gas chromatography, HP model 6890 using fine column HP-5 at different time intervals ranging from 0.5 to 6 hours. The% conversion of longgipolene was calculated using the following equation:

% Conversion rate = [n ₀ -n _f / n ₀ ] x 100

From here,

n ₀ = number of moles of longipolin introduced before the reaction

n _f = number of moles of longipoline remaining in the reaction mixture after the reaction.

Structure characterization of the synthesized catalyst was performed by FT-IR spectroscopy and X-ray powder diffraction. Crystallite size was determined from X-ray diffraction data. Determinations of surface area, pore volume, and pore size were made by nitrogen adsorption at 77 K.

In the present invention, nanocrystalline sulfated zirconia based catalysts have been developed for the single step isomerization of longipolene to selectively produce isorongepolene products. These catalysts showed high activity (> 90% conversion, 100% selectivity) in the absence of solvent.

Sulfide zirconia has a surface pH of the strong acid to be because of the second range (Hammett indicator <-12) to the sulfate group is bonded via an oxygen Zr ^{4 +.} During the sol-gel process, the voids produced in the solid are large enough to promote diffusion of the longipolene / isolongopolene molecules into and out of the active acid sites. Longipoleine double bonds produce carbonium ions upon reaction with acid sites, resulting in rearrangements to form longopolenes.

The inventive progress over the prior art includes: (i) a novel synthesis process for the production of isorongipolene, based on acidic catalysts of solids; (Ii) single or two-stage sols of nanocrystalline sulfide zirconia in acidic, basic, or neutral media for catalytic activity for isomerizing longipolene to isolongepolene to yield isomerized products with very high conversion and selectivity. Synthesis by gel technique, (i) the synthesis of isolongipolene in a single step and solvent-free medium, and (i) at atmospheric pressure for the synthesis of isolongipolene for less than one hour, making the energy of the process efficient. Relatively moderate temperature conditions; (v) the high atomic utilization of the process, due to the fact that no by-products are produced and the catalyst is easily separated and reusable.

The following examples are intended to illustrate the invention, but not to limit the scope of the invention.

Example  One

1.02 mL of concentrated H ₂ SO ₄ diluted in 6.4 mL of water was added dropwise to a 30% solution of Zr (OC ₃ H ₇ ) ₄ in propanol or a zirconium salt such as zirconium nitrate. The hydrated sol was continuously stirred with a magnetic stirrer for 3 hours. The gel formed was first dried at ambient temperature for 3 hours and then at 110 ° C. for 12 hours. The dried gel was powdered to 170 mesh and calcined at 600 ° C. for 2 hours. The prepared sample had a crystallite size of 13 nm as determined by X-ray diffraction. As measured by elemental analysis, the sulfur loaded on the catalyst was 1.2% by weight. 2 g of longipoulene were placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 120 ° C., and 0.2 g of the preactivated catalyst in a muffle furnace at 450 ° C. was added to the reaction for 2 hours. Samples were taken periodically by syringe and analyzed by gas chromatography using an HP-5 column. The percent conversion of longgipolene after 3 to 6 hours was 72 to 75% and the selectivity was 100%.

Example  2

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then, the temperature of the oil bath was gradually raised to the desired temperature, ie 140 ° C., and 0.2 g of the catalyst prepared in the same manner as in Example 1, previously activated in a muffle at 450 ° C. for 2 hours, was added to the reaction. . After 6 hours a sample was taken by syringe and analyzed by gas chromatography using an HP-5 column. After 6 hours, the percent conversion of longgipolene was 85% and the selectivity was 100%.

Example  3

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then, the temperature of the oil bath was gradually raised to the desired temperature, i. . Samples were taken by syringe periodically after 2-6 hours and analyzed by gas chromatography using an HP-5 column. The% conversion of longgipolene after 2 to 6 hours was 84 to 86% and the selectivity was 100%.

Example  4

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.2 g of the catalyst prepared in the same manner as in Example 1, previously activated in a muffle furnace at 450 ° C. for 2 hours, was added to the reaction. . Samples were taken by syringe periodically over 0.5-6 hours and analyzed by gas chromatography using an HP-5 column. The% conversion of longgipolene after 0.5 to 6 hours was 91 to 92% and the selectivity was 100%.

Example  5

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then, the temperature of the oil bath was gradually raised to the desired temperature, 190 ° C., and 0.2 g of the catalyst prepared in the same manner as in Example 1, previously activated in a muffle furnace at 450 ° C. for 2 hours, was added to the reaction. . Samples were taken by syringe after 0.5-4 hours and analyzed by gas chromatography using an HP-5 column. The% conversion of longgipolene after 0.5 to 4 hours was 90 to 92% and the selectivity was 100%.

Example  6

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then, the temperature of the oil bath was gradually raised to the desired temperature, ie 200 ° C., and 0.2 g of the catalyst prepared in the same manner as in Example 1, previously activated in a muffle at 450 ° C. for 2 hours, was added to the reaction. . Samples were taken by syringe periodically after 0.5-4 hours and analyzed by gas chromatography using an HP-5 column. The% conversion of longgipolene after 1 to 4 hours was 91 to 92% and the selectivity was 100%.

Example  7

1.02 mL of concentrated H ₂ SO ₄ was added to a 30% solution of Zr (OC ₃ H ₇ ) ₄ in propanol, and then 6.4 mL of water was added dropwise to this solution. The hydrated sol was continuously stirred with a magnetic stirrer. The gel immediately solidified. The gel formed was first dried at room temperature for 3 hours and then at 110 ° C. for 12 hours. The dried gel was powdered to 170 mesh and calcined at 600 ° C. for 2 hours. The prepared sample had a crystallite size of 11 nm as determined by X-ray diffraction. As measured by elemental analysis, the sulfur loaded on the catalyst was 1.6% by weight. 2 g of longipoulene were placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 140 ° C., and 0.2 g of the preactivated catalyst in the muffle furnace at 450 ° C. for 2 hours was added to the reaction. Samples were taken periodically by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 92% and the selectivity was 100%.

Example  8

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then, the temperature of the oil bath was gradually raised to the desired temperature, i. . Samples were taken periodically by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longifolene was 93% and the selectivity was 85%.

Example  9

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then, the temperature of the oil bath was gradually raised to the desired temperature, ie, 200 ° C., and 0.2 g of the catalyst prepared in the same manner as in Example 7, previously activated in a muffle furnace at 450 ° C. for 2 hours, was added to the reaction. . Samples were taken periodically by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 93% and the selectivity was 80%.

Example  10

Aqueous ammonia solution (25%) was added dropwise to a 30% solution of Zr (OC ₃ H ₇ ) ₄ in propanol until the pH of the mixture reached 9-10. The hydrated sol was continuously stirred with a magnetic stirrer for 3 hours. The gel formed was first dried at room temperature for 3 hours and then at 110 ° C. for 12 hours. The dried gel was powdered to 170 mesh and stirred with 1 NH ₂ SO ₄ (15 mL / g) for 30 minutes. After filtration, it was first dried at room temperature for 3 hours and then at 110 ° C. for 12 hours. The dried gel was powdered to 170 mesh and calcined at 600 ° C. for 2 hours. The prepared sample had a crystallite size of 11 nm as determined by X-ray diffraction. As measured by elemental analysis, the sulfur loaded on the catalyst was 1.4% by weight. 2 g of longipoulene were placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.2 g of the preactivated catalyst in the muffle furnace at 450 ° C. for 2 hours was added to the reaction. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 90% and the selectivity was 100%.

Example  11

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then slowly raise the temperature of the oil bath to the desired temperature, ie 200 ° C., and add 0.2 g of the catalyst prepared in the same manner as in Example 10, previously activated in a muffle furnace at 450 ° C. for 2 hours, to the reaction. It was. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 90% and the selectivity was 100%.

Example  12

6.4 mL of H ₂ O was added dropwise to a 30% solution of Zr (OC ₃ H ₇ ) ₄ in propanol. The hydrated sol was continuously stirred with a magnetic stirrer for 3 hours. The formed gel was first dried at room temperature for 3 hours and then at 110 ° C. for 12 hours. The dried gel was powdered to 170 mesh and stirred with 1 NH ₂ SO ₄ (15 mL / g) for 30 minutes. After filtration, it was first dried at room temperature for 3 hours and then at 110 ° C. for 12 hours. The dried gel was powdered to 170 mesh and calcined at 600 ° C. for 2 hours. The prepared sample had a crystallite size of 100 nm as determined by X-ray diffraction. As measured by elemental analysis, the sulfur loaded on the catalyst was 1.3% by weight. 2 g of longipoulene were placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.2 g of the preactivated catalyst in the muffle furnace at 450 ° C. for 2 hours was added to the reaction. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 92% and the selectivity was 100%.

Example  13

2 g of longifolene were placed in a round bottom flask with two spouts and placed in an oil bath equipped with a temperature controller, magnetic stirrer, condenser, and circulator. Then slowly raise the temperature of the oil bath to the desired temperature, ie 200 ° C., and add 0.2 g of the catalyst prepared in the same manner as in Example 12, preactivated in a muffle furnace at 450 ° C. for 2 hours, to the reaction in the flask. Was added. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 92% and the selectivity was 100%.

Example  14

The catalyst prepared in Example 1 was separated by filtration from the reaction mixture after completion of the reaction described in Example 4 and then washed with 10 mL of ethyl acetate solution at ambient temperature. The catalyst was dried at 110 ° C. for 2-4 hours in an oven and then air calcined at 550 ° C. for 4-8 hours in a muffle furnace. The catalyst was cooled to ambient temperature and then labeled Example 1 -Recycling. 1 g of longipoulene was placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.1 g of the catalyst of Example 1-Recycling was added to the reaction in the flask. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the long conversion was 36% and the selectivity was 100%.

Example  15

The catalyst prepared in Example 7 was separated by filtration from the reaction mixture after completion of the reaction described in Example 8 and then washed with 10 mL of ethyl acetate solution at ambient temperature. The catalyst was dried at 110 ° C. for 2-4 hours in an oven and then air calcined at 550 ° C. for 4-8 hours in a muffle furnace. The catalyst was cooled to ambient temperature and then labeled as Example 2-Recycling. 1 g of longipoulene was placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.1 g of the catalyst of Example 2-recycling was added to the reaction in the flask. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 90% and the selectivity was 100%.

Example  16

The catalyst prepared in Example 10 was separated by filtration from the reaction mixture after completion of the reaction described in Example 10 and then washed with 10 mL of ethyl acetate solution at ambient temperature. The catalyst was dried at 110 ° C. for 2-4 hours in an oven and then air calcined at 550 ° C. for 4-8 hours in a muffle furnace. The catalyst was cooled to ambient temperature and then labeled as Example 10-Recycling. 1 g of longipoulene was placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.1 g of the catalyst of Example 10-Recycling was added to the reaction in the flask. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 90% and the selectivity was 100%.

Example  17

The catalyst prepared in Example 12 was separated by filtration from the reaction mixture after completion of the reaction described in Example 12 and then washed with 10 mL of ethyl acetate solution at ambient temperature. The catalyst was dried at 110 ° C. for 2-4 hours in an oven and then air calcined at 550 ° C. for 4-8 hours in a muffle furnace. The catalyst was cooled to ambient temperature and then labeled as Example 12-Recycling. 1 g of longipoulene was placed in a round bottom flask with two spouts, and the flask was placed in an oil bath equipped with a temperature controller, a magnetic stirrer, a condenser, and a circulator. The temperature of the oil bath was then slowly raised to the desired temperature, ie 180 ° C., and 0.1 g of the catalyst of Example 12-Recycling was added to the reaction in the flask. Samples were taken by syringe and analyzed by gas chromatography using an HP-5 column. After 2 hours, the percent conversion of longgipolene was 91% and the selectivity was 100%.

Advantages of this method over the prior art include the following:

1. The process of the present invention utilizes a solid acid catalyst that is environmentally friendly, safe to handle, and produces no waste or by-products.

2. The process of the present invention is a single step of preparation without using any solvent.

3. Furthermore, the process of the invention is carried out at moderate temperature and pressure conditions.

4. The catalyst, originally in the solid state, can be easily separated from the reaction mixture in the liquid state by filtration or centrifugation.

5. Crystalline and thermally stable catalysts can be regenerated and recycled by heat treatment.

6. Zirconia sulfide solid catalysts are easier in terms of conversion and handling than conventional catalysts such as sulfuric acid, acetic acid, and BF ₃ .OEt ₂ .

Claims (16)

(i) hydrolyzing the zirconium alkoxide and sulphating with sulfuric acid to obtain zirconia sulfide; (Ii) drying the zirconia sulfide and then calcining the dried zirconia sulfide to obtain a nanocrystalline sulfide zirconia catalyst; (Iii) activating the dried sulfide zirconia catalyst obtained in step (ii); (Iii) reacting longipolene with the activated catalyst obtained in step (iii) in a solvent-free medium with a ratio of catalyst to reactant in the range of 2-10% by weight to obtain an isomerization product. step; (Iii) separating the isolongipolene, an isomerization product, from the reaction mixture; (Iii) washing the catalyst to remove adhered material; (Iii) drying the catalyst at 110 ° C. for 2-4 hours and then firing the air at 550 ° C. for 4-8 hours. The process of claim 1, wherein the hydrolysis and sulfation in step (i) is carried out by a single or two stage sol-gel technique, at ambient temperature, in a medium selected from the group consisting of acidic, basic, or neutral media. Manufacturing method characterized in that. The method of claim 1, wherein the zirconia sulfide is dried for 8-12 hours at a temperature of 110 ℃, and then fired for 2-6 hours at 550 ℃ to 650 ℃. The method of claim 1 wherein the dried zirconia sulfide catalyst is activated for 2-4 hours at a temperature in the range of 400-450 ° C. prior to the reaction. The method according to claim 1, wherein the long gifolene reaction is performed for 0.5 to 6 hours under atmospheric pressure while maintaining the reaction temperature in the range of 120 to 200 ° C. The method of claim 1, wherein the isomerization product is characterized in that the separation of isorongipolene is carried out by filtration. The process according to claim 1, wherein the catalyst is washed with ethyl acetate to remove the adhered material. The catalyst of claim 1 wherein the catalyst comprises (i) a crystallite size in the range of 10-100 nm; (Ii) a BET surface area of 80-120 m ² g ⁻¹ ; (Iii) a pore volume of 0.08-0.2 cm ³ g ^-1 and (iii) a pore size of 35-60 mm, comprising nanocrystalline zirconia sulfide in a mostly tetragonal crystalline state with catalytic activity Way. The process according to claim 1, wherein the isomerization of longipolene is carried out in a single step without using any solvent. The method of claim 1, wherein the nanocrystalline zirconia sulfide has a crystallite size in the range of 10 to 100 nm. The method according to claim 1, wherein the nanocrystalline zirconia sulfide has a sulfur content in the range of 0.5 to 2.5% by weight after firing at 600 ° C. The process according to claim 1, wherein the BET surface area of the nanocrystalline sulfide zirconia catalyst is maintained in the range of 80-120 m ² g ⁻¹ . 2. The process according to claim 1, wherein the isomerization of long gifolene has a conversion of at least 90%. The process according to claim 1, wherein the selectivity of isomerization of longgipolene is maintained in the range of 98 to 100%. 2. The process according to claim 1, wherein isomerization of longgipolene is performed with high atomic availability and low E-factor. The method of claim 1 wherein the catalyst is separated and regenerated for recycling.