Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
  • C07C67/333—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by isomerisation; by change of size of the carbon skeleton
  • C07C67/343—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms

Definitions

• the present invention relates to a novel process for preparing 1,4 dions derivatives substituted with al ylidene groups. These compounds are easily convertible into the corresponding alkyl- substituted derivatives that are used as electron donor compounds in the preparation of Ziegler-Natta heterogeneous catalysts for the polymerization of olefins. Transformation of the alkylidene-substituted 1,4 dions derivatives into the matching alkyl- substituted compounds is normally a clean reaction with an almost quantitative yield. Therefore, in order to industrially produce these compounds in an industrially exploitable way, it is necessary to have an economically advantageous process for the production of the corresponding alkylidene-substituted compounds.
• the starting diethyl succinate was used in excess with respect to both the starting ketone (25%) and the base, which in turn was in excess (about 10%) with respect to the ketone.
• the highest yields were obtained using acetone as a ketone and were 92% with respect to the ketone, but much lower with respect to the succinate (76%).
• EP 760,355 disclosed the preparation of a 2-alkylidene-substituted succinate via the Stobbe reaction and using cycloheptanone as starting ketone.
• the base was potassium tert-butoxide and the solvent was dimethylformamide (DMF).
• DMF dimethylformamide
• R 1 , R 2 and R 3 are hydrogen atoms or C ⁇ -C 20 hydrocarbon groups; optionally containing heteroatoms belonging to group 13-17 of the
• R and R can join together to form a saturated or unsaturated C 3 -C I Q ring optionally containing heteroatoms belonging to group 13-17 of the periodic table; with the proviso that when R 1 and R 2 are both hydrogen atoms, only compounds of formula (la) are obtained; preferably R 3 is a hydrogen atom, a linear or branched, saturated or unsaturated C 1 -C 15 alkyl, C 3 -C ⁇ o cycloalkyl, C 6 -C ⁇ o aryl, C 7 -C ⁇ 2 alkylaryl or C 7 -C ⁇ 2 arylalkyl radical; more preferably R is a hydrogen atom, a linear or secondary C ⁇ -C 8 alkyl or C 5 -C 7 cycloalkyl group such as methyl, ethyl ⁇ " isobutyl or cyclohexyl; even more preferably R 3 is a hydrogen atom;
• T 1 and T 2 are H, OR 4 , R 4 , NR 4 2 , SR 4 or PR 4 2 ; or T 1 and T 2 can be fused in an oxygen atom or a TSTR 4 group to form for example compounds of formula (Ic) or (Id):
• R equal to or different from each other, are a C]-C 2 o hydrocarbon group, optionally containing one or more heteroatoms belonging to group 13-17 of the periodic table; preferably R 4 is a linear or branched C ⁇ -C 0 alkyl, C -C ⁇ o cycloalkyl, C 6 -C ⁇ o aryl or a C 7 - C ]2 alkylaryl group; more preferably R 4 is a linear or branched C ⁇ -C 8 alkyl or C 5 -C I Q cycloalkyl group such as methyl, ethyl, isobutyl, tert-butyl or cyclohexyl; preferably T 1 and T 2 are OR 4 , R 4 , NR 4 2 , SR 4 ; more preferably T 1 and T 2 are OR 4 ; said process comprises the step of reacting a compound of formula (II)
• one equivalent means the same amount of basic functionality i.e. the capability to accept an acidic proton.
• one equivalent of K 2 CO 3 means that only 0.5 mole of K 2 CO per mole of compound of formula (ma) or (Illb) are used, for the reason that the anion CO 3 " is able to accept 2 acidic protons.
• one equivalent of KHCO means that one mole of KHCO is used per one mole of compound of formula (Ilia) or (Illb) for the reason that the anion HCO 3 " is able to accept one acidic proton.
• Non limitative examples of a salts of a base or a neutral base are:
• oxides of metal if group 1-13 of the periodic table preferably from groups 1, 2 and 13; such as CaO, BaO and Al O 3 ;
• R 9 compounds of formula NR 3 wherein R 9 equal to or different from each other, are hydrogen atom, or a linear or branched, saturated or unsaturated, Ci-Cio alkyl, C 6 -C 20 aryl, C 7 -C 20 arylalkyl or C -C 0 alkylaryl groups, optionally containing O, S, N, P, Si or halogen atoms, or two or more R form one or more saturated or unsaturated 4 to 7 membered rings, optionally containing O, S, N, P or Si atoms, that can bear substituents; when this ring is aromatic one R 9 can also be a bond part of a double bond to form for example compound like pyridine, or pyrazine; preferably R 9 is a linear or branched, saturated or unsaturated, -Cio alkyl group or two R 9 form a 5 or 6 membered ring such as pyrrole, or the compound of formula R 9 3 is of 1,8- diaza
• M is a metal of groups 1-12 of the periodic table, preferably M is a metal of groups 1, 2 of the periodic table, more preferably M is sodium or potassium.
• Preferred salts are K 2 CO 3 ; KHCO 3 ; Na 2 CO 3 ; NaHCO 3 ;
• Example of salts of a base or t neutral base salts that can be used in the present invention are:
• the amount of the salt of a base or of the neutral base to be used in the process is at least one equivalent with respect to the compound of formula (Ilia) or (IHb). Preferably the amount is between 1 and 4 equivalents, more preferably between 1 and 1.5.
• the molar ratio between the compounds of formula (II) and (Ilia) or (Illb) ranges from 5 to 0.2, preferably from 1.5 to 0.5, more preferably from 1.2 to 1.
• the reaction can be carried out both in protic and aprotic solvent, such as water, or alcohols for protic solvents and toluene, ethylbenzene, xylene, dimethylformammide
• the reaction can also be carried out without solvents when one or more reactanrs are in liquid phase.
• the above process is very suitable for obtaining the 2-alkylidene substituted- 1,4-di ones derivatives in very high yields.
• the applicant found that by carrying out the process according to the above-mentioned conditions the work-up of the final reaction mixtures is very simple. In fact, in most of the cases the work-up comprises only a dilution of the reaction mixture with water and an extraction of the desired products with an appropriate organic solvent, which is then suitably removed.
• One class of preferred compounds among those of formulas (la) or (lb) is that in which R 2 is hydrogen and R 1 is selected from C 4 -C 0 hydrocarbon groups.
• R 1 is C ⁇ -C 8 alkyl, C 5 -C ⁇ o cycloalkyl, C 6 -C ⁇ 0 aryl, C - 2 alkylaryl or C 7 -C ⁇ 2 arylalkyl radical; even more preferred are the compounds in which R 1 is C ⁇ -C 8 alkyl or C 5 -C ⁇ 0 cycloalkyl radical.
• R and R are C ⁇ -C 20 hydrocarbon groups, among them particularly preferred are the compounds in which R 1 and _ . equal to or different from each other, are C ⁇ -C 8 alkyl.
• R 1 and R 2 are: methyl, ethyl, n-propyl, cyclobutyl, but-3-enyl, cyclopropyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, 1-ethylpropyl, cyclohexyl, 4-methylcyclohexyl, 2-methylcyclohexyl, 3-methylcyclohexyl, neo-pentyl, cyclopentyl.
• R and R are the same and chosen among methyl, ethyl or propyl are preferred. Also preferred are the compounds in which R 1 and R 2 are linked together to form a cycle containing from 3 to 10 carbon atoms such as cyclopentyl, cyclohexyl, or cycloheptyl.
• the reactants can be brought into contact with each other according to any order whatsoever.
• the temperature for carrying out the process ranges from 70 to 300°C, more typically from
• the optimum temperature by taking into account parameters like the boiling temperature ofthe reaction medium, that ofthe starting compounds and the desired rate ofthe reaction.
• alkylidene-substituted- 1,4-dions derivatives obtained with the process of the present invention can be converted into the corresponding alkyl-substituted derivatives with methods known in the art. These final compounds are used as electron donor in the preparation of
• Ziegler-Natta heterogeneous catalysts for the polymerization of olefins.
• the alkyl-substituted- 1,4-dions derivatives can be suitably obtained via the catalytic hydro genation, this reaction is well known in the art. A review of this kind of reaction can for example be found in Comprehensive Organic Transformation: a guide to functional group preparation by R. C. Larock published by NCH Publishers.
• catalysts which can be used for carrying out this reaction, particularly preferred are the palladium or platinum deposited on carbon, alumina, BaCO 3 , CaCO 3 or PtO 2 .
• the content of palladium and platinum for deposited catalyst ranges from 0.5 to 30%, preferably from 1 to 10%.
• the temperature at which this reaction is carried out may range from 0 to 150°C, more typically from 40 to 120°C.
• the hydrogen pressure is generally higher than the atmospheric pressure and preferably higher than 15 bar. The skilled in the art can easily select, within these ranges, the optimum temperature by taking into account parameters like the boiling temperature of the reaction medium, that of the starting compounds and the like.
• reaction times for the process ofthe present invention may be from about 1 min to about 30 hours. More conveniently however, the reaction time is comprised from about 10 min to about 8 hours.
• the skilled in the art can control the state of the reaction by following the techniques known in the art and decide when to stop it.
• One subclass of compounds obtainable with the process of the invention are diethyl sec- butylidenesuccinate, diethyl cyclopropylidenesuccinate diethyl cyclohexylidenesuccinate, diethyl benzylidenesuccinate, diethyl cyclohexylmethylidenesuccinate, diethyl isobutylidenesuccinate, diethyl isopropylidenesuccinate, diethyl isopentylidenesuccinate and the corresponding products of formula (lb) and the corresponding compounds esterified with different alkoxy moieties.
• the 2-alkylidene- 1,4-dions derivative obtained with the process of the present invention can be also further substituted on position 3 in a subsequent reaction.
• the second substitution can be carried out by using the Stobbe reaction, as described for example in EP 01202184.6 with subsequent re-esterification of one acidic group and hydrogenation ofthe obtained compound.
• a further object of the present invention is a process for preparing 2, 3-disubstituted- alkylidene-1.4 dions derivatives of formula (INa), (INb) or (Ivc) or a mixture thereof:
• R 1 , R 2 R 4 and T 2 are described above; preferably T 2 is OR 4 ; R 5 and R 6 equal to or different from each other, are hydrogen atoms or C ⁇ -C 0 hydrocarbon groups; optionally c . . containing heteroatoms belonging to group 13-17 of the periodic table; or R and R can join together to form a saturated or unsaturated C 3 -C 10 ring optionally containing heteroatoms belonging to group 13-17 ofthe periodic table; with the proviso that R 5 and R 6 are not hydrogen at the same time; comprising the following steps: a) reacting a compound of formula (II)
• Step a) is substantially equal to the process described above.
• Step b) is preferably carried out under conditions such that: (i) the compound obtained from step a) is used in a molar amount substantially equal to, or lower than, the amount of compound of formula (VI); (ii) the base used in step b) is in a molar amount substantially equal to the compound obtained in step a) and it is selected from hydrides of formula MeH z where Me is a metal belonging to group I-II of the periodic table of elements and z is the valence of the metal and alkoxides of formula R 5 OMe where R 5 is a -C 15 hydrocarbon group and Me has the meaning given above; and (iii) the reaction medium comprises an aprotic liquid medium or a protic liquid medium having a K a , measured'in water, lower than that of iso-propyl alcohol (i-
• the preferred reaction media for step b) are the aprotic diluents and, among them, toluene, ethylbenzene, xylene, dimethylformammide (DMF), N,N-dimethylacetamide, l-methyl-2- pyrrolidone, diethylether, tetrahydrofurane are particularly preferred. Toluene and DMF are especially preferred and DMF is the most preferred. Among protic solvents tert-butanol is one of the most preferred.
• the reaction medium chosen among aprotic liquid medium or a protic liquid medium having a K a , measured in water, lower than that of i-PrOH, should be the largely prevailing medium but may be not the only one.
• small amounts generally not higher than 10% by volume with respect to the total amount of the diluents of liquids not falling within the above classes can in some cases be present for particular purposes.
• one of these liquids is preferably ethanol.
• the base used in step b) is preferably selected among alkoxides of formula R 7 OMe where R 6 is a C ⁇ -C ⁇ 5 hydrocarbon group and Me has the meaning given above. Particularly preferred among them are the alkoxides in which R 6 is a C 1 -C 5 alkyl group and Me is Na or K. Especially preferred compounds are potassium tert-butoxide, sodium tert-butoxide, potassium ethoxide, sodium ethoxide. As a preferred aspect, such preferred alkoxides are used in combination with the aprotic solvents specified above. In particular the combination of the preferred alkoxides with the aprotic solvents like DMF or toluene is especially preferred.
• One class of preferred starting compounds among those of formula (VI) is that in which one of the groups R or R is hydrogen and the other group is selected from C -C 20 hydrocarbon groups, preferably from those not having unsaturation on the carbon atom linked to the carbonyl of formula (VI); particularly preferred are the compounds in which this group is a secondary or tertiary alkyl group.
• Another class of preferred compounds among those of formula (VI) is that in which both R 5 and R 6 are C ⁇ -C 20 hydrocarbon groups preferably not having unsaturation on the carbon atom linked to the carbonyl of formula (VI). Among them particularly preferred are the compounds in which R 5 and R 6 are C ⁇ -C 8 alkyl groups or R 5 and R 6 join together to form cyclic ketones.
• ketones examples include methyl ethyl ketone, methyl n-propyl ketone, cyclobutyl methyl ketone, but-3-enyl methyl 'ketone, acetylcyclopropane, diethyl ketone, methoxyacetone, isopropyl methyl ketone, 2-hexanone, 4-methyl-2-pentanone, methyl sec-butyl ketone, methyl tert-butyl ketone, ethyl n-propyl ketone, ethyl isopropyl ketone, isopentyl methyl ketone, 4-methylcyclohexano ' ne, 2-methylcyclohexanone, 3-methylcyclohexanone, 2,2- dimethyl-3-pentanone, 2-heptanone, 3-heptanone, di-n-propyl ketone, , dicyclopropyl ketone, di-isopropyl ket
• R 5 and R 6 are the same and chosen among methyl, ethyl or propyl are preferred. Also preferred are the compounds in which R and R are linked together to form cyclic ketones like cyclopentanone, cyclohexanone, or cycloheptanone.
• step (b) has a non-esterified carboxylic group formed during this step.
• an esterification step must be carried out which is the step (c) ofthe process ofthe invention.
• the esterification step can be carried out according to any of the many methods known in the art.
• One of the known methods for obtaining esters includes for example the esterification of a carboxylic acid through the reaction with an alcohol catalyzed by an acid or a base.
• a comprehensive review of many methods for preparing the esters can be found in Organic Functional Group Preparation, II Edition, Academic Press 1983.
• the preferred method for carrying out the esterification according to the present invention is the reaction of the product of step (b) with a compound of formula R X where X is halogen and R is C ⁇ -C 20 hydrocarbon group.
• X is selected from Br, CI and I and R 7 is a primary C ⁇ -C 8 alkyl group.
• Particularly preferred R 8 groups are methyl, ethyl, n-propyl, n-butyl and isobutyl. The use of ethyl bromide is especially preferred.
• step (b) This method has the advantage that the alkylidene substituted product of step (b) can directly be reacted with the compound of formula R X without being first subjected to a preliminary work-up thereby saving time and increasing the yields.
• the temperature for carrying out step (c) is not critical. It generally ranges from about -30 to 150°C, more typically from -10 to 110°C.
• steps a), b) and c) are carried out "one pot” i.e. without isolating the intermediate products.
• the saturated derivatives of succinic and 4-oxo-butanoic acids find various applications in the art including the use in the pharmaceutical industry and, as mentioned above, as modifying compounds of Ziegler- ⁇ atta polymerization catalysts.
• reaction mixture was treated with toluene (130 ml) during 8 min.
• a toluene- water mixture (125 ml) was slowly distilled off during 60 min. while gradually increasing the temperature of the reaction mixture from 75 °C back to 150 °C.
• the mixture was treated with acetone (432 mmol) added fast in one portion and then with potassium ethoxide (460 mmol) added during 15 min. using a powder addition funnel.
• the funnel was rinsed with N,N-dimethylformamid (5 10 ml) to transfer all the potassium ethoxide into the reaction flask. After that the reaction mixture was heated to 60 °C and stirred for 30 min.
• reaction mixture was treated with toluene (50 ml) added fast in one portion.
• the reaction flask was then fitted with a 20 ml Dean-Stark receiver, the mixture was heated up to a reflux temperature ( ⁇ 140 °C) and the water formed during the first stage of the reaction was removed by azeotropic drying total 51 ml of a toluene-water mixture were collected during the azeotropic drying and the subsequent distillation.
• reaction mixture was treated with acetone (432 mmol) added fast in one portion, then with a solution of potassium ethoxide (460 mmol) in a mixture of N,N-dimethylformamide (153 ml) and ethanol (26.7 ml) added dropwise during 10 min., and following the completion of the addition stirred at 60 °C for 30 min.
• the mixture was then treated with bromoethane (460 mmol) added fast in one portion, heated up from 60 °C to 80 °C, and stirred at this temperature for 60 min.
• reaction mixture was treated with potassium ethoxide (100 mmol) added fast in one portion, stirred for 30 min., then treated with bromoethane (216 mmol) added fast in one portion, and stirred at the same temperature of 80 °C for additional 60 min.
• the mixture was cooled to 10 °C, quenched with water (333 ml), and then diluted with ether (133 ml). The organic phase was separated and the water phase was extracted with ether (4 x 100 ml).

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