EP1178945A1 - Reactions utilisant les acides de lewis - Google Patents

Reactions utilisant les acides de lewis

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Publication number
EP1178945A1
EP1178945A1 EP00927561A EP00927561A EP1178945A1 EP 1178945 A1 EP1178945 A1 EP 1178945A1 EP 00927561 A EP00927561 A EP 00927561A EP 00927561 A EP00927561 A EP 00927561A EP 1178945 A1 EP1178945 A1 EP 1178945A1
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EP
European Patent Office
Prior art keywords
lewis acid
reaction
aqueous solution
isopulegol
drying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00927561A
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German (de)
English (en)
Inventor
Paul Nicholas Davey
Chi-Lam Tse
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Givaudan Nederland Services BV
Original Assignee
Quest International BV
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Publication date
Application filed by Quest International BV filed Critical Quest International BV
Priority to EP00927561A priority Critical patent/EP1178945A1/fr
Publication of EP1178945A1 publication Critical patent/EP1178945A1/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/17—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrogenation of carbon-to-carbon double or triple bonds
    • C07C29/172—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrogenation of carbon-to-carbon double or triple bonds with the obtention of a fully saturated alcohol
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/003—Preparation involving a liquid-liquid extraction, an adsorption or an ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00—Compounds of zinc
    • C01G9/04—Halides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B63/00—Purification; Separation; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/56—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by isomerisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

Definitions

  • This invention relates to reactions using Lewis acids and concerns a method of performing a chemical reaction involving a Lewis acid, and products resulting from such reaction .
  • Lewis acids in the form of metal salts eg zinc bromide, aluminium chloride etc
  • the Lewis acid commonly functioning as a catalyst, eg in ene-reactions, Diels-Alder reactions, rearrangement reactions and Friedel-Crafts reactions.
  • Lewis acids may also present serious environmental issues on disposal.
  • the Lewis acid zinc bromide
  • the present invention is based on a novel approach to reactions using a Lewis acid that can overcome such practical difficulties.
  • the present invention provides a method of performing a chemical reaction involving a Lewis acid, comprising carrying out the reaction involving the Lewis acid; extracting from the reaction products the Lewis acid in the form of an aqueous solution; and drying the aqueous solution of the Lewis acid.
  • the dried Lewis acid can be reused as a catalyst in a further reaction. It is found that the method of the invention can be repeated several times, using the same batch of Lewis acid, without the activity and selectivity of the Lewis acid being significantly affected.
  • the invention can therefore overcome the problems noted above, enabling quantitative recovery of a Lewis acid and hence enabling repeated reuse of the Lewis acid with consequent reduction in cost of raw materials and avoidance of the cost of disposal of used Lewis acid.
  • the Lewis acid may be, for example, zinc bromide, zinc chloride, zinc iodide, other metal salts, or mixtures thereof.
  • the Lewis acid is zinc bromide.
  • the invention is applicable to a range of chemical reactions using Lewis acids, including ene-reactions, Diels- Alder reactions, rearrangement reactions and Friedel-Crafts reactions.
  • the desired chemical reaction may be carried out in a suitable organic solvent, such as cyclohexane, benzene, xylene, toluene or mixtures thereof.
  • a suitable organic solvent such as cyclohexane, benzene, xylene, toluene or mixtures thereof.
  • the currently preferred solvent is toluene as it gives good reaction rates and selectivity. Toluene is also a cheap, safe solvent and so is well suited to industrial use.
  • the Lewis acid is conveniently extracted from the reaction products by adding water, preferably deionised water, and separating the aqueous fraction typically from an organic solvent fraction containing the reaction products.
  • Drying of the aqueous solution of the Lewis acid may be performed using techniques including vacuum dehydration; chemical drying eg with dried molecular sieve material, anhydrous magnesium sulphate or sodium sulphate; physical drying techniques, for instance pervaporisation with selective membrane technology; azeotropic distillation; or a mixture of such techniques.
  • the drying of the aqueous solution of the Lewis acid is performed by azeotropic distillation.
  • Azeotropic distillation may be performed using any suitable solvent that gives an azeotrope with water, is inert to the Lewis acid, has a low solubility in water and preferably is suitable for the reaction.
  • suitable solvents include, but are not limited to, cyclohexane, benzene, xylene and toluene. Preferred for use herein is toluene.
  • the dried Lewis acid in the solvent is ready for reuse in a reaction and it is simply necessary to add further reagents.
  • the Lewis acid can be recycled and reused in this way several times.
  • the method of the invention may be preceded by an initial step of drying the Lewis acid so that it is in a stable state to take part in the reaction.
  • the initial drying step may be carried out independently of the reaction, or alternatively, the Lewis acid may be dried in situ in a reaction mixture. Whether it is appropriate to dry the Lewis acid in situ will depend upon whether the reactants and products of a particular reaction are thermally stable under the drying conditions employed and whether the optimum temperature for carrying out the reaction is compatible with the temperature at which the Lewis acid is dried. Typically, either means of drying the Lewis acid reactivates it to act as a catalyst in the reaction.
  • Drying may be performed by the techniques described above, and is preferably performed by azeotropic distillation eg with toluene of an aqueous solution of the Lewis acid. Drying the Lewis acid by this method has the beneficial consequence that it is not necessary to use the Lewis acid reagent in anhydrous form.
  • Some Lewis acids, eg zinc bromide are expensive in their anhydrous form and difficult to maintain in anhydrous condition, being hygroscopic. It is thus beneficial not to have to use the reagent in anhydrous form but instead to be able to use an aqueous solution of Lewis acid, which is a cheaper starting material that does not require special storage and handling.
  • the invention provides a method of performing a chemical reaction involving a Lewis acid, comprising the steps of:
  • step 3 adding water to the reaction products of step 2) and separating an aqueous solution of the Lewis acid;
  • Steps 1) to 3) can be repeated several times, thus reusing the same Lewis acid in several reactions, without significantly affecting the activity and specificity of the Lewis acid in the reaction.
  • the invention provides a method for performing an ene reaction involving a Lewis acid.
  • the invention has been used to good effect in the preparation of 2-isopropenyl- 5-methylcyclohexanol, known as isopulegol, from 3,7-dimethyl-6-octenal, known as citronellal, by a catalytic ene reaction.
  • Isopulegol and citronellal both exist in two enantiomeric forms, which are respectively (lR,2S,5R)-2-isopropenyl-5-methylcyclohexanol and (lS,2R,5S)-2-isopropenyl-5-methylcyclohexanol; and (7S)-3,7-dimethyl-6-octenal and (7R)-3,7-dimethyl-6-octenal.
  • Mixtures of enantiomers of each of these materials are nevertheless referred to in this specification in the singular, eg as isopulegol, so that references to isopulegol may refer to one or other enantiomeric form or a mixture of enantiomers. Similar considerations apply to citronellal.
  • Isopulegol is a known fragrance material, with its most important use being as a precursor for (lR,2S,5R)-2-isopropyl-5-methylcyclohexanol, known as 1-menthol, prepared by a known hydrogenation reaction.
  • 1-menthol or (-)-menthol
  • isopulegol by cyclisation of citronellal using a Lewis acid catalyst. Powdered anhydrous zinc bromide has been found to be one of the most selective catalysts in the cyclisation reaction, as described in Nakatani et al, Synthesis 1978, 147.
  • zinc bromide is required in stoichiometric amounts and is effectively consumed in the process, and moreover can present waste disposal problems, being not only a marine toxin, but also a water pollutant as described above.
  • Zinc bromide is also hygroscopic and wet zinc bromide is much less reactive than the anhydrous form. Hence precautions are required in the storage and usage of zinc bromide to avoid moisture.
  • a method of preparing isopulegol from citronellal comprising reacting citronellal in the presence of a Lewis acid catalyst to cause cyclisation of citronellal to produce isopulegol; extracting from the reaction products the Lewis acid in the form of an aqueous solution; and drying the aqueous solution of the Lewis acid.
  • isopulegol exists in two enantiomeric forms.
  • 1-menthol is generally the most preferred form of menthol, as noted above.
  • the invention can produce isopulegol in good yields.
  • the dried Lewis acid can be reused in the cyclisation of a further batch of citronellal to isopulegol, without loss of reactivity and selectivity.
  • the invention can therefore overcome the problems noted above associated with the prior art, enabling quantitative recovery of Lewis acid and hence enabling repeated reuse of Lewis acid with consequent reduction in cost of raw materials and avoidance of the cost of disposal of used zinc bromide.
  • the Lewis acid may be, for example, zinc bromide, zinc chloride, zinc iodide, other metal salts or mixtures thereof.
  • Zinc bromide generally gives the best yield and selectivity and so is favoured in the conversion of citronellal to isopulegol.
  • the cyclisation reaction is carried out in a suitable organic solvent, such as cyclohexane, benzene, xylene, toluene or mixtures thereof.
  • a suitable organic solvent such as cyclohexane, benzene, xylene, toluene or mixtures thereof.
  • the currently preferred solvent is toluene as it gives good reaction rates and selectivity. Toluene is also a cheap, safe solvent and so is well suited to industrial use.
  • the cyclisation reaction is conveniently carried out at a temperature in the range -15°C to 30°C, with a temperature of about 0°C giving good compromise results in terms of yield and selectivity.
  • the Lewis acid is conveniently extracted from the reaction products by adding water, preferably deionised water, and separating the aqueous fraction from the organic solvent fraction containing isopulegol.
  • Drying of the aqueous solution of the Lewis acid may be performed using techniques including vacuum dehydration; chemical drying eg with dried molecular sieve material, anhydrous magnesium sulphate or sodium sulphate; physical drying techniques, for instance pervaporisation with selective membrane technology; azeotropic distillation; or a mixture of such techniques.
  • azeotropic distillation is currently favoured as the resulting dried Lewis acid is found to give best product yields and selectivity. It may be convenient to precede azeotropic distillation by optional vacuum dehydration.
  • Azeotropic distillation may be performed using any suitable solvent that gives an azeotrope with water, is inert to the Lewis acid, has low solubility in water and preferably is suitable for the cyclisation reaction. Suitable solvents include those mentioned above, ie cyclohexane, benzene, xylene and toluene, with toluene currently being favoured.
  • the dried Lewis acid in the solvent is ready for reuse in the cyclisation reaction and it is simply necessary to add a further batch of citronellal.
  • the Lewis acid can be recycled and reused in this way several times without loss of catalytic activity and selectivity.
  • the preferred method of the invention will generally be preceded by an initial step of drying the Lewis acid so that it is in a suitable state to act as a catalyst in the cyclisation reaction. Drying may be performed by the techniques described above, and is preferably performed by azeotropic distillation with toluene of an aqueous solution of the Lewis acid. Such initial drying has the beneficial consequence that it is not necessary to use as a reagent anhydrous Lewis acid, eg zinc bromide. Anhydrous zinc bromide is expensive and difficult to maintain in anhydrous condition as it is a hygroscopic material; instead an aqueous solution of Lewis acid can be used as a reagent, which is a cheaper starting material that does not require special storage and handling.
  • anhydrous Lewis acid eg zinc bromide.
  • Anhydrous zinc bromide is expensive and difficult to maintain in anhydrous condition as it is a hygroscopic material; instead an aqueous solution of Lewis acid can be used as a reagent, which
  • the invention thus provides a method of preparing isopulegol from citronellal, comprising the steps of:
  • step 3 adding water to the reaction products of step 2) and separating an aqueous solution of zinc bromide from the toluene solution of isopulegol;
  • Steps 1) to 3) can be repeated several times, thus reusing the same zinc bromide on several batches of citronellal, without significantly affecting the activity and specificity of the zinc bromide in the cyclisation reaction.
  • the method can give good yields of isopulegol of desired optical form even after repeated re-use of the zinc bromide.
  • the invention can thus provide an environmentally acceptable and efficient process for the production of isopulegol from citronellal, in both racemic and enantiomerically pure forms.
  • the invention includes within its scope isopulegol prepared by the method of the invention.
  • the isopulegol can be converted into menthol, eg by hydrogenation.
  • the invention also covers use of the isopulegol so prepared for the preparation of menthol, and the resulting menthol.
  • the invention enables conversion of d-citronellal to 1-isopulegol and then 1- menthol, while a racemic starting material produces racemic products.
  • the invention provides a method for performing a Diels-Alder reaction involving a Lewis acid.
  • the structure of the diene and dienophile employed in the Diels-Alder reaction will often determine the rate of reaction. Depending on the nature of the reactants, a faster rate of reaction may be brought about, for example, by conducting the reaction at high temperatures or by employing a catalyst. Catalytic Diels-Alder reactions tend to be more selective in the product formed than the corresponding thermally induced reactions.
  • the invention however has been used to good effect in catalytic Diels-Alder reactions, specifically, in the preparation of intermediates of perfumery ingredients.
  • the invention may be employed to good effect in the Diels-Alder reaction of 7- methyl-3-methylene-l,6-octadiene, known as myrcene, with 3-methyl-3-penten-2-one to give a mixture of l-[l,6-dimethyl-3-(4-methyl-3-pentenyl)-3-cyclohexen-l-yl]ethanone and l-[l,6-dimethyl-4-(4-methyl-3-pentenyl)-3-cyclohexen-l-yl]ethanone as follows:
  • the products of the Diels-Alder reaction afford a mixture of bicyclic compounds which are useful intermediates in the preparation of perfumery ingredients having a floral, woody and ambergris odour.
  • the Diels-Alder reaction is conveniently carried out at a temperature in the range 100°C to 140°C, preferably 100°C to 130°C. Additionally, the Diels-Alder reaction is carried out in a suitable solvent, such as for example, toluene.
  • the preferred Lewis acid in the Diels-Alder reaction is zinc bromide, wherein zinc bromide is preferably employed as an aqueous solution.
  • the aqueous solution of the Lewis acid may be dried in situ during the course of the Diels-Alder reaction by azeotropic distillation using toluene when both the reactants and Diels-Alder adducts are stable under these drying conditions and the temperature for carrying out the Diels-Alder reaction is typically, the same as the temperature for drying the Lewis acid.
  • the Lewis acid is then extracted from the reaction products by adding water, and separating the aqueous fraction from the organic solvent fraction containing the Diels-Alder adducts.
  • the recovered aqueous solution of the Lewis acid may then be subject to further drying in situ in a further Diels-Alder reaction of myrcene with 3-methyl-3-penten-2-one, thus, being reused as a catalyst in this reaction.
  • the invention includes within its scope l-[l,6-dimethyl-3-(4-methyl-3-pentenyl)-3- cyclohexen- 1 -yl] ethanone and 1 -[ 1 , 6-dimethyl-4-(4-methy 1-3 -pentenyl)-3 -cyclohexen- 1 - yl]ethanone prepared by the method of the invention.
  • the invention provides a method for performing a rearrangement reaction involving a Lewis acid.
  • Lewis acids are capable of activating functional groups such as for example aldehydes, ketones, epoxides, acetals and olefins to induce a rearrangement of the molecule.
  • the invention has been used successfully in rearrangement reactions, specifically in the rearrangement of 2,7,7-trimethyl-3-oxatricyclo[4.1.1.0 2 ' 4 ]octane, known as ⁇ -pinene oxide, to (2,2,3-trimethyl-3-cyclopenten-l-yl)acetaldehyde, known as campholenic aldehyde, as is shown below:
  • aldehyde is a useful intermediate in the synthesis of a variety of woody, musky and sandalwood fragrance ingredients.
  • a method of preparing (2,2,3-trimethyl-3-cyclopenten-l-yl)acetaldehyde from 2,7,7-trimethyl-3- oxatricyclo[4.1.1.0 2 ' ]octane comprising reacting 2,7,7-trimethyl-3-oxatricyclo[4.1.1.0 2 ' 4 ] octane in the presence of a Lewis acid catalyst to cause rearrangement of 2,7,7-trimethyl-3- oxatricyclo[4.1.1.0 2 ' 4 ] octane to produce (2,2,3-trimethyl-3-cyclopenten-l-yl) acetaldehyde; extracting from the reaction products the Lewis acid in the form of an aqueous solution; and drying the aqueous solution of the Lewis acid.
  • the rearrangement reaction is conveniently carried out at a temperature in the range 100°C to 140°C.
  • the preferred Lewis acid in this rearrangement reaction is zinc bromide and the reaction is typically carried out in toluene.
  • the reaction may be preceded by an initial step of drying the Lewis acid.
  • the Lewis acid is extracted from the reaction products by adding water, and separating the aqueous fraction from the organic solvent fraction containing campholenic aldehyde.
  • the recovered aqueous solution of zinc bromide is then conveniently dried by azeotropic distillation using toluene. After azeotropic drying, the dried zinc bromide in toluene is ready for use in a further rearrangement reaction of ⁇ - pinene oxide. Good yields of campholenic aldehyde are obtained.
  • the dried Lewis acid can be recycled and reused in the conversion of two further batches of ⁇ -pinene oxide to campholenic aldehyde, without loss of activity or selectivity.
  • the invention thus includes within its scope (2,2,3-trimethyl-3-cyclopenten-l- yl)acetaldehyde prepared by the method of the invention.
  • Example 1 Drying of zinc bromide and preparation of isopulegol
  • Racemic citronellal (68.80g, 0.45 mol) was added to the suspension over 3 hours by pump at 0.4g/min. at 2-5°C and stirred vigorously.
  • the resulting mixture was stirred for another 1.5 hours.
  • GC the reaction was completed by this stage.
  • the reaction mixture was then quenched with deionised (DI) water (3x100ml).
  • DI deionised
  • the organic layer was then washed with brine (1x50ml).
  • the yield of isopulegol was found to be 87.14% by GC analysis.
  • the zinc content of the aqueous solution was determined by atomic absorption analysis and it was found that zinc was totally recovered in the aqueous extraction.
  • the recovered zinc bromide was dried and used in a further cyclisation reaction under the same conditions.
  • 200ml toluene was added to the zinc bromide solution, and the mixture was refluxed with a D&S trap for 8 hours.
  • Citronellal was pumped in to the suspension at 0.4g/min. for 2 hours 15 min at 2-5°C. 53.95g citronellal was added and the solution was stirred for a further 3 hours.
  • GC the reaction was complete by this stage.
  • the reaction mixture was then washed with deionised water (2x50ml).
  • the yield of isopulegol was found to be 85.85%) by GC analysis.
  • the diastereoselectivity of the two cycles were similar.
  • Example 2 Experiments similar to those of Example 1 using azeotropic drying of toluene were carried out on a larger scale using reagents from the same source. The experiments were carried out using a 10 litre jacketed reactor with a Dean & Stark trap, condenser, mechanical stirrer and thermocouple.
  • step (c) To the suspension resulting from step (c) cooled to 0°C and stirred vigorously ( ⁇ 80rpm), racemic citronellal was pumped in at 4.76g/min. 600.16g citronellal was added after 2 hours and 6 min. The solution (most of the zinc bromide was dissolved at this point) was further stirred at +1-0°C for 1.5 hours. According to GC and TLC, the reaction was completed by this stage. To the reaction mixture, 600ml DI water was added with stirring. The aqueous phase was separated and removed. The organic phase was washed with another 600ml DI water and separated. The yield of isopulegol was found to be 87.90%) by GC analysis with similar disastereoselectivity when compared with the first cycle.
  • step (c) To the 1.2 litre zinc bromide solution from step (d), procedure (c) was applied. A pinkish suspension of zinc bromide in toluene resulted.
  • step (e) Third Cycle, Cyclisation of Citronellal.
  • citronellal was pumped in at 4.76g/min. 694.61g citronellal was added after 2 hours and 40 min. The solution (most of the zinc bromide was dissolved at this point) was further stirred at +2-0°C for 1.5 hours.
  • GC and TLC the reaction was completed by this stage.
  • 600ml DI water was added with stirring. The aqueous phase was separated and removed. The organic phase was washed with another 600ml DI water and separated.
  • the yield of isopulegol was found to be 82.26%o by GC analysis with similar disastereoselectivity compare with the first cycle.
  • step (g) To the suspension resulting from step (g) cooled to 0°C and stirred vigorously ( ⁇ 80rpm), racemic citronellal was pumped in at 4.76g/min. 600. lOg citronellal was added after 2 hours and 14 min. The solution (most of the zinc bromide was dissolved at this point) was further stirred at +2-0°C for 1.5 hours. According to GC and TLC, the reaction was completed by this stage. To the reaction mixture, 600ml DI water was added with stirring. The aqueous phase was separated and removed. The organic phase was washed with another 600ml DI water and separated. The yield of isopulegol was found to be 86.22%> by GC analysis with similar disastereoselectivity compared with the first cycle.
  • the heating was continued for 12 hours, after which time, the reaction was found to be complete by GC analysis.
  • the reaction mixture was cooled to 50°C under nitrogen. 25ml deionised water was then added to the reaction mixture, stirred for 15 minutes and the aqueous and organic layers were allowed to separate. The aqueous layer containing the zinc bromide solution was removed and the organic layer washed with another 25ml portion of deionised water.
  • the crude reaction mixture comprising the Diels-Alder adducts contained in the toluene organic layer was analysed by internal standard GC and the conversion was found to be 95%> (based on the amount of myrcene used) and the selectivity was 76%>. Hence the combined %> yield of the Diels-Alder adducts based on myrcene was 71.96%).
  • Carrier gas Nitrogen
  • Temp Program 140°C, hold 5 minutes, ramp 40°C/min to 220°C, hold 8 min.; total run time 15 min.
  • Example 6 Diels-Alder reaction of myrcene and 3-methyl-3-penten-2-one with recycled zinc bromide.
  • the heating was continued for 12 hours, after which time, the reaction was found to be complete by GC analysis.
  • the reaction mixture was cooled to 50°C under nitrogen. 25ml deionised water was then added to the reaction mixture and stirred for 15 minutes, and the aqueous and organic layers were allowed to separate. The aqueous layer containing the zinc bromide solution was removed and the organic layer was washed with another 25ml portion of deionised water.
  • the crude reaction mixture comprising the Diels- Alder adducts contained in the toluene organic layer was then analysed by internal standard GC and the conversion was found to be 97% (based on the amount of myrcene used) and the selectivity was 75%. Hence the combined % yield of the Diels-Alder adducts based on myrcene was 73.27%.
  • Zinc bromide ex Aldrich, purity 98%, Cat. No.: 21,632-1
  • ⁇ -Pinene oxide (10.61g, 69.8mmol) in 50ml toluene was added to the zinc bromide suspension dropwise from an addition funnel over 2 hours.
  • the temperature of the reaction mixture during the addition was kept at 113-117°C (toluene was gently refluxed) and the reaction vigorously stirred. After the addition was complete, the temperature of the reaction was maintained at 113-117°C and the mixture was further stirred for 90 minutes.
  • the reaction was found to be complete after this time by GC analysis.
  • the reaction mixture was then cooled to room temperature and 25ml deionised water was added to the reaction mixture.
  • the aqueous layer was removed and the organic layer was washed with another 25ml of deionised water and separated.
  • the organic layer was found to contain 128.35g of crude product.
  • the crude product was analysed by internal standard GC and found to contain 6.17%> campholenic aldehyde. Hence the yield of the reaction was 76

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Catalysts (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

Dans un procédé de réaction chimique utilisant un acide de Lewis, cet acide de Lewis, une fois la réaction achevée, est extrait du produit de réaction sous la forme d'une solution aqueuse qui est ensuite séchée. L'acide de Lewis séché peut être réutilisé dans une autre réaction similaire. Le procédé peut être répété plusieurs fois, en utilisant le même lot d'acide de Lewis, sans que l'activité et la spécificité de l'acide Lewis en soient considérablement affectées. Cette invention a été utilisée à bon effet dans la réaction ène d'isopulégol à partir de citronellal, dans la réaction Diels-Alder de myrcène et 3-méthyl-3-penten-2-one et la réaction de réarrangement d'oxyde α-pinène en aldéhyde campholénique à l'aide du bromure de zinc comme catalyseur, acide de Lewis. Cette invention offre ainsi un procédé d'utilisation, efficace et ménageant l'environnement des acides de Lewis dans des procédés industriels.
EP00927561A 1999-05-17 2000-05-11 Reactions utilisant les acides de lewis Withdrawn EP1178945A1 (fr)

Priority Applications (1)

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EP00927561A EP1178945A1 (fr) 1999-05-17 2000-05-11 Reactions utilisant les acides de lewis

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP99303812 1999-05-17
EP99303812A EP1053974A1 (fr) 1999-05-17 1999-05-17 Réactions utilisant des acides de Lewis
EP00927561A EP1178945A1 (fr) 1999-05-17 2000-05-11 Reactions utilisant les acides de lewis
PCT/GB2000/001793 WO2000069777A1 (fr) 1999-05-17 2000-05-11 Reactions utilisant les acides de lewis

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EP1178945A1 true EP1178945A1 (fr) 2002-02-13

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JP (1) JP2002544245A (fr)
AU (1) AU4595300A (fr)
MX (1) MXPA01011259A (fr)
WO (1) WO2000069777A1 (fr)
ZA (1) ZA200109303B (fr)

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US6515186B2 (en) 2001-05-08 2003-02-04 Millennium Specialty Chemicals Process for obtaining alpha-campholenic aldehyde
DE102004011543A1 (de) * 2004-03-08 2005-10-06 Basf Ag Verfahren zur Herstellung optisch aktiver Carbonylverbindungen
DE102004049631A1 (de) * 2004-10-11 2006-04-20 Basf Ag Verfahren zur Herstellung optisch aktiver Carbonylverbindungen
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