Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D311/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings
  • C07D311/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D311/04—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D311/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings
  • C07D311/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D311/04—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring
  • C07D311/58—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4
  • C07D311/70—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4 with two hydrocarbon radicals attached in position 2 and elements other than carbon and hydrogen in position 6
  • C07D311/72—3,4-Dihydro derivatives having in position 2 at least one methyl radical and in position 6 one oxygen atom, e.g. tocopherols
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P3/00—Drugs for disorders of the metabolism
  • A61P3/02—Nutrients, e.g. vitamins, minerals

Definitions

• the present invention relates to a novel process for the manufacture of chroman derivatives, especially for the manufacture of ⁇ -tocopherol (TCP) and alkanoates (TCPA) thereof such as ⁇ -tocopheryl acetate (TCPAc), whereby at least one step of the process is carried out in the presence of a Lewis acid or a mixture of a Lewis acid with a Bronsted acid as the catalyst under pressure.
• TCP ⁇ -tocopherol
• TCPAc ⁇ -tocopheryl acetate
• the absolute pressure of the reaction is at least 1.1 bar, more preferably it is from about 1.1 bar to about 20.0 bar, even more preferably it is from about 1.1 bar to about 6.0 bar.
• TCP and its alkanoates either a mixture of 2,3,5-trimethylhydroquinone (TMHQ) or 2,3,6-trimethylhydroquinone-1-alkanoate (TMHQA) and a compound selected from the group consisting of phytol (pH), isophytol (IP) and (iso)phytol derivatives, or the “open ring” compound 2-phytyl-3,5,6-trimethylhydroquinone (PTMHQ), a 3-phytyl-2,5,6-trimethylhydroquinone-1-alkanoate (PTMHQA) and/or an isomer thereof are used.
• TMHQ 2,3,5-trimethylhydroquinone
• THQA 2,3,6-trimethylhydroquinone-1-alkanoate
• a compound selected from the group consisting of phytol (pH), isophytol (IP) and (iso)phytol derivatives or the “open ring” compound 2-phytyl-3,5,6-trimethylhydro
• (all-rac)- ⁇ -tocopherol (or as it has mostly been denoted in the prior art, “d,1- ⁇ -tocopherol”) is a mixture of four diastereomeric pairs of enantiomers of 2,5,7,8-tetramethyl-2-(4′,8′,12′-trimethyl-tridecyl)-6-chromanol ( ⁇ -tocopherol), which is the biologically most active and industrially most important member of the vitamin E group.
• TMHQ and IP PH or a PH derivative are reacted in the presence of a mineral acid, a Lewis acid, an acidic ion exchange resin or a triflate, nitrate or sulfate of Sc, Y or a lanthanide element as the catalyst.
• a mineral acid a Lewis acid, an acidic ion exchange resin or a triflate, nitrate or sulfate of Sc, Y or a lanthanide element
• Sc(III) triflate as catalyst for the condensation of TMHQ with IP is also described in Bull. Chem. Soc. Jpn. 1995, 68, 3569-3571.
• TCP can be converted into its acetate, succinate and further known application forms by standard methods, e. g. as described in Ullmann's Encyclopedia of Industrial Chemistry, Vol. A27, 5 th edition, pages 484 to 485, VCH Verlagsgesellschaft mbH, D-69451 Weinheim, 1996.
• esters In contrast to TCP which is labile against oxidative conditions, the esters (TCPA) are more stable and more convenient to handle.
• the object of the present invention is to provide a process for the manufacture of chroman derivatives such as tocols and tocopherols and of their alkanoates, especially of ⁇ -tocopherol and its alkanoates, with high selectivities and yields.
• this object is achieved by the use of a Lewis acid or a mixture of a Lewis acid with a Bronsted acid as the catalyst under pressure, preferably at an absolute pressure of at least 1.1 bar, more preferably at an absolute pressure of from about 1.1 bar to about 20.0 bar, even more preferably at an absolute pressure of from about 1.1 bar to about 6.0 bar. It has been surprisingly found that pressure has a positive effect on the condensation reaction of phenols such as TMHQ or TMHQA with compounds such as IP, PH or a derivative thereof and on the ring closure reaction of PTMHQ or PTMHQA and/or isomers thereof to produce ⁇ -tocopherol as well as on the acylation of tocols and tocopherols.
• R 2 is hydroxy, acetyloxy, benzoyloxy or halogen
• n is an integer from 0 to 3
• reaction is carried out in the presence of a Lewis acid or a mixture of a Lewis acid with a Bronsted acid as the catalyst under pressure, preferably at an absolute pressure of at least 1.1 bar, more preferably at an absolute pressure of from about 1.1 bar to about 20.0 bar, even more preferably at an absolute pressure of from about 1.1 bar to about 6.0 bar.
• This process is referred to as PROCESS 1 hereinafter.
• substituent R 1 preferably it is hydrogen or acetyl, more preferably it is hydrogen.
• R 2 is hydroxy, acetyloxy, benzoyloxy, chlorine or bromine, more preferably R 2 is hydroxy, acetyloxy or chlorine, most preferably R 2 is hydroxy.
• n preferably n is 3.
• PROCESS 1 of the present invention the production of (all-rac)-2-alkenyl-3,5,6-trimethylhydroquinone, e.g. (all-rac)-PTMHQ, or (all-rac)-3-alkenyl-2,5,6-trimethylhydroquinone 1-alkanoate, e.g. (all-rac)-PTMHQA, especially (all-rac)-3-phytyl-2,5,6-trimethylhydroquinone-1-acetate (PTMHQAc), is preferred, the invention is not limited to the production of that particular isomeric form and other isomeric forms can be obtained by using e.g.
• (R,R)-PTMHQ or (R,R)-PTMHQA will be obtained e.g. when using (R,R)-phytol, (R,R,R)-isophytol, (S,R,R)-isophytol or (RS,R,R)-isophytol or an appropriate (iso)phytol derivative.
• PROCESS 1 is also applicable for the alkenylation of phenols comprising 0 to 4 methyl groups, a total of 1 to 3 hydroxy groups and at least one unsubstituted position, whereby the unsubstituted position is ortho to a hydroxy group.
• a further object of the present invention is a process for the alkenylation of phenols comprising 0 to 4 methyl groups, a total of 1 to 3 hydroxy groups and at least one unsubstituted position, whereby the unsubstituted position is ortho to a hydroxy group, with a compound of the formula III and/or IV in an organic solvent with R 2 and n having the same meanings and preferences as above, and
• Especially suitable phenols have the following formula IIa with R 3 being hydrogen, acetyl, propionyl, pivaloyl, HO 2 C—CH 2 —CH 2 —CO, nicotinoyl or benzoyl, and X 1 , X 2 and X 3 being independently from each other hydrogen or methyl, with the proviso that R 3 is only acetyl, propionyl, pivaloyl, HO 2 C—CH 2 —CH 2 —CO, nicotinoyl or benzoyl, if X 1 , X 2 and X 3 are all methyl; i.e.
• hydroquinone 2-methylhydroquinone, 2,3-dimethylhydroquinone, 2,5-dimethylhydroquinone, 2,6-dimethylhydroquinone, 2,3,5-trimethylhydroquinone and 2,3,6-trimethylhydroquinone-1-alkanoates.
• Preferred from this group are 2,3,5-trimethylhydroquinone and 2,3,6-trimethylhydroquinone-1-alkanoates, more preferred are 2,3,5-trimethylhydroquinone and 2,3,6-trimethylhydroquinone-1-acetate, the most preferred is 2,3,5-trimethylhydroquinone.
• PROCESS 3 As starting material in PROCESS 3 also a compound of the formula IX instead of a compound of the formula III and/or IV may be used, so that compounds of the formula X are obtained.
• R 1 , R 2 and n have the same meanings and preferences as above. To this process it will be referred to in the following as PROCESS 4.
• phytol, isophytol or a derivative thereof as the starting material in the appropriate isomeric form will be obtained when using (R,R)-PTMHQ, (R,R)-PTMHQA, (R,R)-phytol, (R,R,R)-isophytol, (S,R,R)-isophytol or (RS,R,R)-isophytol or an appropriate (iso)phytol derivative.
• the present invention is concerned with a process for the manufacture of compounds of the formula VIIa by
• step b) (STEP b) submitting in an organic solvent a compound of the formula Ia and optionally one or more double bond isomers thereof, all obtainable by step a), to ring closure to form a compound of the formula VIla, whereby at least one of the steps a) and b) is carried out in the presence of a Lewis acid or a mixture of a Lewis acid with a Bronsted acid as the catalyst under pressure, preferably at an absolute pressure of at least 1.1 bar, more preferably at an absolute pressure of from about 1.1 bar to about 20.0 bar, even more preferably at an absolute pressure of from about 1.1 bar to about 6.0 bar.
• PROCESS 2A To this process it will be referred to in the following as PROCESS 2A.
• step a of PROCESS 2A can also proceed to the final products, the compounds of the formula VIIa, so that the compounds of the formula Ia are not isolated.
• a further aspect of the present invention is the manufacture of a compound of the formula VIla by reacting a compound of the formula IIa with a compound of the formula III and/or IV in an organic solvent with R 2 , R 3 , n, X 1 , X 2 and X 3 having the same meanings and preferences as above, whereby the reaction is carried out in the presence of a Lewis acid or a mixture of a Lewis acid with a Bronsted acid as the catalyst under pressure, preferably at an absolute pressure of at least 1.1 bar, more preferably at an absolute pressure of from about 1.1 bar to about 20.0 bar, even more preferably at an absolute pressure of from about 1.1 bar to about 6.0 bar.
• PROCESS 3A To this process it will be referred to in the following as PROCESS 3A.
• the reaction is carried out in the presence of a Lewis acid as the catalyst.
• the reaction is carried out at reduced pressure, preferably at an absolute pressure of below 0.9 bar, or under pressure, preferably at an absolute pressure of at least 1.1 bar (in the following referred to as PROCESS 5).
• n it is an integer from 0 to 3.
• R it is selected from the group consisting of acetyl, propionyl, pivaloyl, HO 2 C—CH 2 —CH 2 —CO, nicotinoyl or benzoyl; preferably R is HO 2 C—CH 2 —CH 2 —CO or acetyl, more preferably R is acetyl.
• R it is selected from the group consisting of acetyl, propionyl, pivaloyl, HO 2 C—CH 2 —CH 2 —CO, nicotinoyl or benzoyl; preferably R is HO 2 C—CH 2 —CH 2 —CO or acetyl, more preferably R is acetyl.
• Lewis acids and mixtures of Lewis acids with Bronsted acids known to the person skilled in the art as catalysts for the condensation reaction of TMHQ or TMHQA with IP, PH or derivatives thereof can be used.
• Suitable catalysts are e.g. bortrifluoride (BF 3 ), a mixture of boric acid (especially orthoboric acid) and oxalic acid, triflates and heterowolfram acids.
• Preferred are Lewis acids, where the radius of the metal cation varies from about 73 pm to about 90 pm, preferably from about 73 pm to about 82 pm, such as the radius of Fe 2+ (0.74 ⁇ ), Zn 2+ (0.74 ⁇ ), In 3+ (0.81 ⁇ ) and Sc 3+ (0.73 ⁇ ).
• InCl 3 , In(OTf) 3 and Sc(OTf) 3 are more preferred, whereby InCl 3 is the most preferred one.
• the indium and scandium salts InCl 3 , In(OTf) 3 and Sc(OTf) 3 are known compounds which are commercially available, InCl 3 e.g. from Fluka (No. 57 100), In(OTf) 3 and Sc(OTf) 3 e.g. from Aldrich (No. 442 151 and 418 218). They can be used in solid form, anhydrous or hydrated (of which InCl 3 .4 H 2 O is an example), as well as in solution or in suspension.
• the catalyst is preferably dissolved or suspended in water.
• the concentration of such an aqueous solution is not critical. Furthermore, all the Lewis acids cited above tolerate acetic anhydride and other acylating agents as well as protic solvents such as acetic acid, methanol, ethanol and water. After the termination of the reaction the Lewis acids used as the catalysts can be recycled.
• Suitable mixtures of Lewis acids with Bronsted acids are the following systems: zinc(II) compounds/hydrochloric acid, zinc(II) compounds (preferably ZnCl 2 )/gaseous HCl and Fe(II) chloride/gaseous HCl.
• the Fe(II) chloride can be prepared in situ by the reaction of Fe with HCl, which therefore presents an equivalent system to the system Fe(II) chloride/gaseous HCl.
• Suitable zinc(II) compounds are zinc(II) salts such as ZnCl 2 , ZnBr 2 as well as all zinc(II) compounds which form ZnCl 2 under the reaction conditions, e.g. ZnO.
• the reaction is carried out in the presence of an amine such as disclosed in the last paragraph on page 4 and the first paragraph on page 5 of EP 0 100 471 A1, which is hereby incorporated by reference, or in the presence of an ammonium salt.
• the reaction is preferably carried out by using the compound of the formula III or IV such as IP or PH having been pretreated with an amine or NH 3 as described in DE-OS 26 06 830.
• the starting material TMHQAc may be obtained e.g. by selective hydrolysis of 2,3,5-trimethylhydroquinone diacetate as described in EP-A 1 239 045.
• 2,3,5-Trimethylhydroquinone diacetate can be prepared e.g. by the acid catalyzed rearrangement of ketoisophorone in the presence of acetic anhydride or another acetylation agent as described in EP-A 0 850 910, EP-A 0 916 642, EP-A 0 952 137 or EP-A 1 028 103.
• the (iso)phytyl compounds can be produced by conventional processes known to the person skilled in the art.
• Preferred is the use of phytol and its derivatives represented by the formula IV as E/Z-mixtures.
• the most preferred starting material selected from the (iso)phytyl compounds is IP.
• (R,R)-phytol, (R,R,R)-isophytol, (S,R,R)-isophytol or (RS,R,R)-isophytol or an appropriate (iso)phytol derivative e.g. can be used to obtain (R,R)-PTMHQ/(R,R)-PTMHQA or (RS,R,R)-TCP/(RS,R,R)-TCPA, if TMHQ/TMHQA is used as the other component.
• PROCESS 1 STEP a of PROCESS 2
• PROCESS 2a STEP a of PROCESS 2a
• step a and b of PROCESS 2 the reaction proceeds to the final product (steps a and b of PROCESS 2) or is slowly enough so that these intermediates can be isolated (only step a of PROCESS 2 is performed). The same applies for the steps a and b of PROCESS 2a.
• TMHQ is reacted with PH and/or IP, more preferably with IP.
• reaction is carried out under an inert gas atmosphere, preferably gaseous nitrogen or argon.
• the reaction is preferably carried out at an absolute pressure of at least 1.1 bar, more preferably at an absolute pressure of from about 1.1 to about 20.0 bar, even more preferably at an absolute pressure of from about 1.1 bar to about 6.0 bar, even more, more preferably at an absolute pressure of from about 1.7 to about 5.1 bar, most preferably at an absolute pressure of from about 2.0 to about 3.6 bar.
• the reaction temperature depends on the applied pressure and solvent because the reaction is carried out under reflux. Therefore, the reaction temperature is conveniently from about 90° C. to about 170° C., preferably from about 90° C. to about 160° C., more preferably from about 112° C. to about 160° C. and most preferably from about 125 to about 150° C.
• Suitable organic solvents are aprotic non-polar organic solvents such as aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons, halogenated aromatic hydrocarbons and mixtures thereof.
• Preferred examples of aliphatic hydrocarbons are linear, branched or cyclic C 5 - to C 15 -alkanes. Particularly preferred are linear, branched or cyclic C 6 - to C 10 -alkanes, especially preferred are hexane, heptane, octane and cyclohexane or mixtures thereof.
• halogenated aliphatic hydrocarbons are mono- or polyhalogenated linear, branched or cyclic C 1 - to C 15 -alkanes. Especially preferred examples are mono- or polychlorinated or -brominated linear, branched or cyclic C 1 - to C 15 -alkanes. More preferred are mono- or polychlorinated linear, branched or cyclic C 1 - to C 15 -alkanes. Most preferred are 1,1,1-trichloroethane, 1,2-dichloroethane, methylene chloride and methylene bromide.
• aromatic hydrocarbons are benzene, toluene, o-, m- and p-xylene, 1,2,3-trimethylbenzene, mesitylene, pseudocumene, naphthalene and mixtures thereof, particularly preferred is toluene.
• halogenated aromatic hydrocarbons are mono-or polyhalogenated benzene. Especially preferred are chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene and 1,4-dichlorobenzene.
• the most preferred non-polar solvents differ from catalyst to catalyst:
• toluene and heptane are the preferred solvents; especially preferred is heptane.
• Sc(OTf) 3 is used as the catalyst, the most preferred solvent is toluene.
• process 1 or step a) of process 2/2a in the presence of an amine such as disclosed in the last paragraph on page 4 and the first paragraph on page 5 of EP 0 100 471 A1, which is hereby incorporated by reference.
• the process can also be carried out by pretreating the compound of the formula III or IV such as IP or PH with an amine or NH 3 as described in DE-OS 26 06 830.
• the most preferred solvent for carrying out the reaction with the Zn(II) catalyst system is hexane. If no amine is present, the most preferred solvent for carrying out the reaction with the Zn(II) catalyst system is heptane.
• the molar ratio of the compound of the formula II or Ia (most preferred: TMHQ or TMHQA(c)) to a compound of the formula III or IV, whichever is employed, in the reaction mixture conveniently varies from about 0.95:1 to about 1:1.1, preferably from about 1:1.01 to about 1:1.05.
• the amount of the aprotic non-polar organic solvent used is conveniently from about 0.1 ml to about 6.0 ml, preferably from about 0.15 ml to about 3.0 ml, based on 1 mmol of the compound of the formula III or IV, whichever is employed.
• the relative amount of catalyst, based on compound III or IV, whichever is employed, is dependent on the catalyst system used and the reactants. Conveniently the relative amount of the catalyst based on compound III or IV, whichever is employed, is at least 0.01 mol %. Generally the relative amount of catalyst varies from about 0.01 to about 30 mol %. The optimal relative amount of the catalyst is different from catalyst to catalyst and also depends on the reactants:
• InCl 3 is used as the catalyst, it may be preferably present e.g. in a relative amount of from about 0.1 mol % to about 2.5 mol %, especially preferable in a relative amount of from about 0.1 mol % to about 2.0 mol %, more preferably in a relative amount of from about 0.1 to about 1.0 mol %, even more preferably in a relative amount of from about 0.1 to about 0.5 mol %, based on compound III or IV, whichever is employed.
• Sc(OTf) 3 is used as the catalyst, it may be preferably present in a relative amount of from about 0.05 mol % to about 2.0 mol %, preferably in a relative amount of from about 0.075 to about 1.5 mol %, more preferably in a relative amount of from about 0.1 to about 1.0 mol %, based on compound III or IV, whichever is employed.
• Fe and/or FeCl 2 in combination with HCl may be present in an amount as described e.g. in DE-OS 21 60 103 (page 5, end of second paragraph and claim 9 ) and in U.S. Pat. No. 3,789,086 (column 3, lines 27-60).
• Zn(II) and/or ZnCl 2 is used as the catalyst, it may be present in an amount as described e.g. in the examples 1 to 12 of U.S. Pat. No. 2,411,967, in U.S. Pat. No. 3,708,505 (page 1, right column, lines 26-44), in DE-OS 196 54 038 (page 2, lines 55-63; page 3, lines 4-6; page 3, line 60 to page 4, line 19; page 4, line 29-38), in EP-A 0 100 471 (page 7, lines 19-24), in DE-OS 26 06 830 (page 4, last two lines to page 5, first two paragraphs), in U.S. Pat. No. 4,191,692 (second column, lines 49-62).
• the expression “amount of catalyst” is to be understood as referring to the weight of pure Lewis acid or pure Bronsted acid present, even though the catalyst may be impure, in the form of an adduct with a solvent and/or a solution/suspension.
• the relative amount of the Bronsted acid depends also on the Lewis acid used and can be chosen accordingly.
• the reaction can be carried out batchwise or continuously, and in general operationally in a very simple manner, for example (i) by adding the compound of the formula III or IV—as such or dissolved in the solvent, preferably as such—portionwise or continuously to a mixture of the Lewis acid, the compound of the formula IIa/II (preferred: TMHQ or TMHQA; most preferred: TMHQ or TMHQAc) and the solvent. If a catalyst system consisting of a Lewis acid and a Bronsted acid is employed, the Bronsted acid is added continuously or batchwise, preferably continuously, to the mixture of the Lewis acid, the compound of the formula Ia/II (most preferred: TMHQ or TMHQA(c)) and the solvent.
• TMHQ or TMHQA most preferred: TMHQ or TMHQA(c)
• the compound of the formula III or IV is added continuously to the compound of the formula IIa/II (most preferred: TMHQ or TMHQA(c)) within about 15 to about 180 minutes, preferably within about 30 to about 150 minutes, more preferably within about 45 to about 130 minutes.
• the Lewis acid is preferably added at once, i.e. in its full amount, to the mixture of the compound of the formula IIa/II (most preferred: TMHQ or TMHQA(c)) and the solvent.
• reaction mixture After completion of the addition of the compound of the formula III or IV (in the non-polar solvent) the reaction mixture is suitably heated further at the reaction temperature for about 10 minutes to about 360 minutes, preferably for about 30 minutes to about 240 minutes.
• the working-up can be effected by procedures conventionally used in organic chemistry.
• a compound of the formula II or IIa with R 1 and R 3 , respectively, being hydrogen such as PTMHQ or an isomer thereof as a reactant in the process of this invention will result in the preparation of a tocol or a tocopherol such as ⁇ -tocopherol while, when using a compound of the formula II with R 1 being acetyl, propionyl, pivaloyl, HO 2 C—CH 2 —CH 2 —CO, nicotinoyl or benzoyl and n being 3 the respective tocyl alkanoate or tocopheryl alkanoate such as ⁇ -tocopheryl alkanoate will be obtained.
• PTMHQ or PTMHQA For the manufacture of ⁇ -tocopherol or ⁇ -tocopheryl alkanoate PTMHQ or PTMHQA and optionally one or more isomers thereof, which are obtained as minor by-products in the manufacture of PTMHQ or PTMHQA, prepared to any method known to the person skilled in the art can be used as starting material.
• This reaction can be carried out using the same catalysts under substantially the same reaction conditions as described above for step a) of PROCESS 2 and 2a.
• the amount of catalyst and the reaction temperature the reaction stops at the intermediates of the formula Ia/I or proceeds to the end products of the formula VII/VIla.
• This reaction can be carried out using the same catalysts under substantially the same reaction conditions as described above for step a) of PROCESS 2 and 2a.
• the reaction proceeds to the final product of the formula X independent from the nature of the catalyst, the amount of catalyst and the reaction temperature.
• a compound of the formula VIIc such as e.g. ⁇ -tocopherol or ⁇ -tocopherol, or any other tocol as described in DE-OS 21 60 103 on page 5 in the third and forth paragraph may be converted into its alkanoate (a compound of the formula VIIIa), e.g. its acetate, by treatment with an acylating agent in the presence of a Lewis acid as the catalyst at reduced pressure, preferably at an absolute pressure of below 0.9 bar, or under pressure, preferably at an absolute pressure of at least 1.1 bar.
• the absolute reaction pressure varies from about 0.02 bar to about 0.9 bar (even more preferably from about 0.1 bar to about 0.9 bar, most preferably from about 0.2 bar to about 0.9 bar) and from about 1.1 bar to about 10.0 bar (even more preferably from about 1.1 bar to about 6.0 bar, even more, more preferably from about 1.1 bar to about 5.0 bar, most preferably from about 1.1 bar to about 3.0 bar).
• the invention is also directed to a process for the manufacture of tocyl alkanoates in the presence of a Lewis acid as the catalyst at reduced pressure, preferably at an absolute pressure of below 0.9 bar, or under pressure, preferably at an absolute pressure of at least 1.1 bar.
• acylation in accordance with that aspect of the invention can be carried out using acylating agents conventionally used in the acylation of tocopherols such as anhydrides or halides.
• Examples of these are anhydrides or halides of alkanoic acids such as acetic acid, propionic acid, pivalic acid, succinic acid, nicotinic acid and benzoic acid.
• acetic anhydride or acid chloride, especially acetic anhydride are/is used.
• the molar ratio of the compound of the formula VIIc to the acylating agent in the reaction mixture conveniently varies from about 1:1 to about 1:5, preferably from about 1:1 to about 1:3, more preferably from about 1:1.1 to about 1:2.
• Suitable Lewis acids are the ones named above.
• the amount of the Lewis acid used as the catalyst is based on the lesser molar amount of reactant, i.e. the compound of the formula VIIc or the acylating agent, and can be in the range of from about 0.006 mol % to about 2.0 mol %, preferably from about 0.0075 mol % to about 1.5 mol %, more preferably from about 0.01 mol % to about 1.0 mol %, in the batchwise mode of operation.
• the amount of catalyst will be adjusted to the size of the reactor and the flow of the reactants. It will be appreciated that the determination of the appropriate figures based on the figures for batchwise operation is within normal skill.
• the Lewis acid is added at once, i.e. in its full amount.
• the catalyst is added as an aqueous solution or suspension.
• the temperature of the acylation is dependent on the catalyst system used and the temperature the reactants (resulting from former process steps) already have.
• the acylation reaction can be generally carried out at temperatures from about 20 to about 200° C., preferably from about 60 to about 180° C., more preferably from about 80 to about 160° C.
• the acylation reaction is preferably carried out at temperatures below 120° C., more preferably from about 15 to about 120° C., most preferably at room temperature, i.e. from about 15 to about 40° C.
• reaction can be carried out essentially in the absence of an additional organic solvent, which is preferred.
• Essentially in the absence of an additional organic solvent in the context of the present invention means that essentially no organic solvent is present during the reaction and that no organic solvent is deliberately added. It might, however, be possible that traces of organic solvent are present in the starting materials or the catalyst as impurities.
• the reaction is carried out in substance; i.e. no other compound except the compound of the formula VIIc, the acylating agent and the catalyst is intendedly used for the reaction, so that at the beginning of the reaction the amount of any substance except for the starting material, the compound of the formula VIIc and the acylating agent, and except for the catalyst in the reaction mixture is ⁇ 5 weight %, preferably ⁇ 3 weight %, more preferably ⁇ 0.5 weight %, and that no further compound is added during the reaction
• the reaction is conveniently carried out under an inert gas atmosphere, preferably gaseous nitrogen or argon.
• the ⁇ -tocopherol or its alkanoate obtained by one of the processes of the present invention can further be formulated by any method known to the person skilled in the art, e.g. as those disclosed in U.S. Pat. No. 6,162,474, US 2001/0009679, U.S. Pat. No. 6,180,130, U.S. Pat. No. 6,426,078, U.S. Pat. No. 6,030,645, U.S. Pat. No. 6,150,086, U.S. Pat. No. 6,146,825, U.S. Pat. No. 6,001,554, U.S. Pat. No. 5,938,990, U.S. Pat. No. 6,530,684, U.S. Pat. No.
• Jeffsol EC50® is a solvent mixture available from Huntsman Corp., PO Box 15730 Austin, Tex., USA/Antwerp 2030, Belgium, which consists of ethylene carbonate and propylene carbonate in the volume ratio 1:1.
• TMHQ (24.691 g, 161.1 mmol) and IP (38.833 ml, 107.4 mmol, 97%, added during 1 hour) were reacted in a molar ratio of 1.5:1 in the presence of 1.0 mol % of In(OTf) 3 as the catalyst (amount based on IP) at 22° C. and at atmospheric pressure.
• 1.0 mol % of In(OTf) 3 as the catalyst (amount based on IP) at 22° C. and at atmospheric pressure.
• Table 2 After separation of the heptane phase and washing of the heptane phase with Jeffsol EC50® (250 ml) the resulting suspension in heptane was filtered under vacuum. The pasty nearly colorless solid was analysed by quantitative GC.
• TMHQ 200 mmol of TMHQ were reacted with 200 mmol of IP (examples 10 and 13) and 203 mmol of IP (examples 11, 12 and 14), respectively, in the presence of increasing amounts of In(OTf) 3 (example 10) or InCl 3 (examples 11-14) as the catalyst in 100 ml of an organic solvent.
• examples 10 and 14 were carried out under pressure, whereby examples 11-13 were carried out at atmospheric pressure.
• examples 11-13 were carried out at atmospheric pressure.
• the amount of solvent was 100 ml in all cases.
• the amount of TMHQ was 200 mmol in all cases.
• TCP [%] time Pressure Selectivity Example Catalyst Solvent [hour/s] [bar] for TCP [%] 18 InCl 3 Toluene 1 2.0 95.7 20* InCl 3 Toluene 2 2.0 95.5 21 InCl 3 Heptane 1 3.4 89.5 22* InCl 3 Heptane 2 3.4 93.9 23 In(OTf) 3 Toluene 1 2.0 72.3 24 In(OTf) 3 Heptane 1 3.4 65.6 *molar excess of IP of 1.38%
• Example [mol %] Solvent [bar] [%] 12 0.5 Heptane 1.0 18.5 19 0.5 Heptane 3.4 92.0 20 2.0 Toluene 2.0 95.5 22 2.0 Heptane 3.4 93.9 25 0.5 Toluene 2.0 90.2 26 0.25 Toluene 2.0 85.1 27 0.25 Heptane 3.4 81.5
• Example 35 was repeated but the reaction was carried out at a higher temperature and at a higher pressure. For details and the results see Table 9 and 12.
• Example 32 was repeated, but instead of 0.1 mol % of Sc(OTf) 3 1.0 mol % of Sc(OTf) 3 were used.
• Example 38 was repeated with the same amounts of TMHQ, IP and Fe.
• the amount of HCl and the time for the addition of IP were, however, different.
• the pressure, under which the reaction was carried out was also slightly different in the examples 39-41. For further details and the results see Table 10 and 13 (examples 41 and 42 only).
• Example 46 was repeated but the reaction was carried out under an absolute pressure of 2.1 bar instead of 1.0 bar. Further details and the results are shown in Table 10. TABLE 10 Comparison between experiments at atmospheric pressure (examples 43-46) and under pressure (examples 38-42 and 47) in toluene (under reflux) with Fe/HCl as the catalyst; the conversion of IP was 100% in all cases. All yields and selectivities are based on IP.
• Example 48 was repeated, but the reaction carried out under an absolute pressure of 2.1 bar and not at 1.0 bar. Further details and the results are given in Table 11.
• Example 50 was repeated, but instead of 403 mmol of IP 404 mmol of IP were added and instead of 5.3 g of gaseous HCl 49.9 g of gaseous HCl were used. For further details and the results see Table 11.
• Example 51 was repeated with the amounts of TMHQ, IP, ZnCl 2 , tridecyl amine and gaseous HCl given in Table 11. The reaction, however, was not carried out at 2.2 bar, but at 1.0 bar. The results are presented in Table 11.
• Example 51 was repeated with the amounts of TMHQ, IP, ZnCl 2 , tridecyl amine and gaseous HCl given in Table 11. The reaction, however, was not carried out in hexane, but in heptane. The results are presented in Table 11 and 13. TABLE 11 Comparison between experiments at atmospheric pressure (1.0 bar) and under pressure (2.1-2.2 bar) in heptane under reflux (examples 48, 49 and 53) or hexane under reflux (examples 50-52) with ZnCl 2 /HCl (g) as the catalyst. IP was added during one hour in all cases. All yields and selectivities are based on IP. The conversion of IP was 100% in all cases.
• Tridecyl [%] Selectivity TMHQ/IP [mol %] - amine HCl Pressure for TCP Example [mmol/mmol] based on IP [10 ⁇ 3 kg] [10 ⁇ 3 kg] [bar] [%] 48 322/320 18.3 0 39.9 1.0 75.9 49 322/320 18.3 0 40.0 2.1 86.6 50 394/403 22.7 1.2 5.3 2.2 94.9 51 394/404 22.7 1.2 49.9 2.2 94.1 52 394/402 22.8 1.2 50.0 1.0 77.8 53 394/400 22.8 1.2 49.9 2.2 91.0
• InCl 3 shows a higher selectivity for the formation of TCP than In(OTf) 3 and Sc(OTf) 3 .
• TABLE 13 Detailed results and comparison of selectivity for a mixture of Bronsted with Lewis acids as the catalyst Example 41 42 53 Amount of TMHQ to IP 595/617 595/617 394/400 [mmol/mmol] Catalyst Fe + HCl Fe + HCl ZnCl 2 + HCl + tri- decyl amine Amount of catalyst [mol %] 0.5 Fe 0.5 Fe 23.0 ZnCl 2 Amount of gaseous HCl [g] 39.9 60.2 49.9 Solvent toluene toluene heptane Temperature of the 135-146° C.

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