Process for the preparation of polyisoprene with a mainly alternating cis-1,4- alt-3,4 structure in the presence of a catalytic system comprising a pyridyl iron complex
11746167 · 2023-09-05
Assignee
Inventors
- Giovanni Ricci (Parma, IT)
- Anna Sommazzi (Novara, IT)
- Guido Pampaloni (Pontedera, IT)
- Giuseppe Leone (Milan, IT)
- Francesco Masi (Sant'angleo Lodigiano, IT)
Cpc classification
International classification
B60C1/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
Process for the preparation of polyisoprene with a mainly alternating cis-1,4-alt-3,4 structure comprising polymerizing isoprene in the presence of a catalytic system comprising: (a) at least one pyridyl iron complex having general formula (I): ##STR00001## wherein: R.sub.1 is selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups; R.sub.2 is selected from linear or branched C.sub.1-C.sub.10, preferably C.sub.1-C.sub.3, alkyl groups; X, mutually identical or different, represent a halogen atom such as, for example, chlorine, bromine, iodine; or they are selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups, —OCOR.sub.3 groups or —OR.sub.3 groups wherein R.sub.3 is selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.15, alkyl groups. n is 2 or 3; (b) at least one co-catalyst selected from organo-derivative compounds of aluminum, preferably from (b.sub.1) aluminoxanes having general formula (II):
(R.sub.4).sub.2—Al—O—[—Al(R.sub.5)—O—].sub.m—Al—(R.sub.6).sub.2 (II) wherein R.sub.4, R.sub.5 and R.sub.6, mutually identical or different, represent a hydrogen atom, or a halogen atom such as, for example, chlorine, bromine, iodine, fluorine; or they are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, said groups being optionally substituted with one or more silicon or germanium atoms; and m is an integer ranging from 0 to 1000; (b.sub.2) aluminum compounds having general formula (III):
Al(R.sub.7)(R.sub.8)(R.sub.9) (III) wherein R.sub.7 is a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkoxy groups; R.sub.8 and R.sub.9, mutually identical or different, are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, arylalkyl groups; wherein the molar ratio between the aluminum present in the co-catalyst and the iron present in the iron pyridyl complex having general formula (I) is ranging from 5 to 60, preferably from 8 to 55.
Claims
1. A process for the preparation of polyisoprene with a mainly alternating cis-1,4-alt-3,4 structure the process comprising: polymerizing isoprene in the presence of a catalytic system, the system comprising: (a) at least one pyridyl iron complex having general formula (I): ##STR00013## wherein: R.sub.1 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, optionally substituted cycloalkyl groups, and optionally substituted aryl groups; R.sub.2 is selected from linear or branched C.sub.1-C.sub.10 alkyl groups; X, mutually identical or different, represents a halogen atom; or X is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, —OCOR.sub.3 groups and —OR.sub.3 groups wherein R.sub.3 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; n is 2 or 3; (b) at least one co-catalyst selected from (b1) aluminoxanes having general formula (II):
(R.sub.4).sub.2—Al—O—[—Al(R.sub.5)—O—].sub.m—Al—(R.sub.6).sub.2 (II) wherein R.sub.4, R.sub.5 and R.sub.6, mutually identical or different, represent a hydrogen atom or a halogen atom; or R.sub.4, R.sub.5 and R.sub.6 are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, and aryl groups, the groups being optionally substituted with one or more silicon or germanium atoms; and m is an integer ranging from 0 to 1000; (b2) aluminum compounds having general formula (III):
Al(R.sub.7)(R.sub.8)(R.sub.9) (III) wherein R.sub.7 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, arylalkyl groups, alkoxy groups; R.sub.8 and R.sub.9, mutually identical or different, are selected from linear or branched C.sub.1-C.sub.20 alkyl groups, cycloalkyl groups, aryl groups, alkylaryl groups, and arylalkyl groups; wherein the molar ratio between aluminum present in the co-catalyst and iron present in the pyridyl iron complex having general formula (I) ranges from 5 to 60.
2. The process according to claim 1, further comprising the pyridyl iron complex having general formula (I), wherein: R.sub.1 represents a methyl group, an ethyl group, an n-propyl group, or an iso-propyl group; R.sub.2 represents a methyl group, an ethyl group, an n-propyl group, or an iso-propyl group; X, mutually identical, represents a halogen atom such as chlorine, bromine, or iodine atom; and n is 2 or 3.
3. The process according to claim 1, wherein the aluminoxanes having general formula (II) are selected from: methylaluminoxane (MAO), ethylaluminoxane, n-butylaluminoxane, tetra-iso-butylaluminoxane (TIBAO), tert-butylaluminoxane, tetra-(2,4,4-trimethylpentyl)aluminoxane (TIOAO), tetra-(2,3-dimethylbutyl)aluminoxane (TDMBAO), tetra-(2,3,3-trimethylbutyl)aluminoxane (TTMBAO), and mixtures thereof.
4. The process according to claim 1, wherein the aluminum compounds having general formula (III) are selected from: diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, di-iso-butyl-aluminum hydride (DIBAH), diphenylaluminum hydride, di-p-tolylaluminum hydride, dibenzyl aluminum hydride, diethylaluminum hydride, phenyl-n-propylaluminum hydride, p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride, p-tolyl-iso-propylaluminum hydride, benzylethylaluminum hydride, benzyl-n-propylaluminum hydride, benzyl-iso-propylaluminum hydride, diethylaluminum ethoxide, di-iso-butyl aluminum dioxide, dipropylaluminum ethoxide, trimethylaluminum, triethylaluminum (TEA), tri-n-propylaluminum, tri-iso-butylaluminum (TIBA), tri-n-butylaluminum, tripentylaluminum, trihexaluminum, tricyclohexylaluminum, trioctylaluminum, triphenylaluminum, tri-p-tolylalluminium, tribenzylaluminum, ethyldiphenylaluminum, ethyldi-p-tolylaluminum, etildibenzylaluminum, diethylphenylaluminum, diethyl-p-tolylaluminum, diethylbenzylaluminum, and mixtures thereof.
5. The process according to claim 1, wherein: the process is carried out in the presence of at least one inert organic solvent selected from the group consisting of: saturated aliphatic hydrocarbons; saturated cycloaliphatic hydrocarbons; mono-olefins; aromatic hydrocarbons; halogenated hydrocarbons; and/or the concentration of the isoprene in the inert organic solvent is ranges from 5% by weight to 50% by weight, with respect to the total weight of the mixture of isoprene and inert organic solvent; and/or the process is carried out at a temperature ranging from −30° C. to +60° C.
6. The process according to claim 1, wherein the linear or branched C.sub.1-C.sub.20 alkyl groups of R.sub.1 is linear or branched C.sub.1-C.sub.15 alkyl groups.
7. The process according to claim 1, wherein the linear or branched C.sub.1-C.sub.20 alkyl groups of R.sub.3 is linear or branched C.sub.1-C.sub.15 alkyl groups.
8. The process according to claim 1, wherein the linear or branched C.sub.1-C.sub.10 alkyl groups of R.sub.2 is linear or branched C.sub.1-C.sub.3 alkyl groups.
9. The process according to claim 1, wherein the halogen atom is selected from the group consisting of chlorine, bromine, iodine, and fluorine.
10. The process according to claim 2, wherein R.sub.1 represents a methyl group; R.sub.2 represents a methyl group or an iso-propyl group; and X, mutually identical, represents a chlorine atom.
11. The process according to claim 5, wherein the saturated aliphatic hydrocarbons are selected from the group consisting of: butane, pentane, hexane, heptane, and mixtures thereof.
12. The process according to claim 5, wherein the mono-olefins are selected from the group consisting of: 1-butene, 2-butene, and mixtures thereof.
13. The process according to claim 5, wherein the saturated cycloaliphatic hydrocarbons are selected from the group consisting of: cyclopentane, cyclohexane, and mixtures thereof.
14. The process according to claim 5, wherein the aromatic hydrocarbons are selected from the group consisting of: benzene, toluene, xylene, and mixtures thereof.
15. The process according to claim 5, wherein the halogenated hydrocarbons are selected from the group consisting of: dichloromethane, chloroform, carbon tetrachloride, trichlorethylene, perchloroethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene, chlorotoluene, and mixtures thereof.
16. The process according to claim 5, wherein the process is carried out at a temperature ranging from −20° C. to +30° C.
17. The process according to claim 5, wherein the concentration of the isoprene in the inert organic solvent ranges from 10% by weight to 20% by weight, with respect to the total weight of the mixture of isoprene and inert organic solvent.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE DISCLOSURE
(22) For the purpose of understanding the present invention better and to put it into practice, below are some illustrative and non-limiting examples thereof.
EXAMPLES
(23) Reagents and Materials
(24) The list below reports the reagents and the materials used in the following examples of the invention, any optional pre-treatments thereof and their manufacturer: iron (III) chloride (FeCl.sub.3) (Aldrich): purity 99.9%, used as such; iron (II) chloride (FeCl.sub.2) (Aldrich): purity 97%, used as such; neodymium 2-ethylhexanoate [Nd(OCOC.sub.7H.sub.15).sub.3] (Strem Chemicals): used as such; methylaluminoxane (MAO) (toluene solution 10% by weight) (Crompton): used as such; tri-iso-butylaluminum (TIBA) (Akzo Nobel): used as such; diethylaluminum chloride (AlEt.sub.2Cl) (Akzo Nobel): used as such; hydrochloric acid in 37% aqueous solution (Aldrich): used as such; o-toluidine (Aldrich): distilled at reduced pressure and stored in an inert atmosphere; 2-iso-propylaniline (Aldrich): used as such; 2-acetylpyridine (Aldrich): used as such; ethyl acetate (Aldrich): used as such; heptane (Aldrich): pure, ≥99%, distilled over sodium (Na) in an inert atmosphere; methanol (Carlo Erba, RPE): used as such; toluene (Aldrich): pure, ≥99.5%, distilled over sodium (Na) in an inert atmosphere; isoprene (Aldrich): pure, ≥99%, refluxed over calcium hydride for 2 hours, then distilled “trap-to-trap” and stored in a nitrogen atmosphere at +4° C.; formic acid (HCOOH) (Aldrich): purity 95%, used as such; p-toluenesulfonic acid monohydrate (Aldrich): pure, 98.5%, used as such; hydrofluoric acid (HF) (40% aqueous solution) (Aldrich): used as such; sulfuric acid (H.sub.2SO.sub.4) (96% aqueous solution) (Aldrich): used as such, or diluted with distilled water (1/5); nitric acid (HNO.sub.3) (70% aqueous solution) (Aldrich): used as such; sodium carbonate (Na.sub.2CO.sub.3) (Aldrich): used as such; silver nitrate (AgNO.sub.3) (Aldrich): used as such; deuterated tetrachloroethylene (C.sub.2D.sub.2Cl.sub.4) (Acros): used as such; hexamethyldisilazane (HMDS) (Acros): used as such.
(25) The analysis and characterization methodologies reported below were used.
(26) Elementary Analysis
(27) a) Determination of Fe
(28) For the determination of the quantity by weight of iron (Fe) in the pyridyl iron complexes used for the purpose of the present invention, an exactly weighed aliquot, operating in dry-box under nitrogen flow, of about 30 mg-50 mg of sample, was placed in a 30 ml platinum crucible, together with a 1 ml mixture of 40% hydrofluoric acid (HF), 0.25 ml of 96% sulphuric acid (H.sub.2SO.sub.4) and 1 ml of 70% nitric acid (HNO.sub.3). The crucible was then heated on a hot plate increasing the temperature until white sulfur fumes appeared (about +200° C.). The mixture thus obtained was cooled to ambient temperature and 1 ml of 70% nitric acid (HNO.sub.3) was added, then it was left again until fumes appeared. After repeating the sequence another two times, a clear, almost colorless, solution was obtained. 1 ml of nitric acid (HNO.sub.3) and about 15 ml of water were then added cold, then heated to +80° C. for about 30 minutes. The sample thus prepared was diluted with MilliQ pure water until it weighed about 50 g, precisely weighed, to obtain a solution on which the instrumental analytical determination was carried out through a Thermo Optek IRIS Advantage Duo ICP-OES (plasma optical emission) spectrometer, for comparison with solutions of known concentration. For this purpose, for every analyte, a calibration curve was prepared in the range 0 ppm-10 ppm, measuring calibration solutions by dilution by weight of certified solutions.
(29) The solution of sample prepared as above was then diluted again by weight in order to obtain concentrations close to the reference ones, before carrying out spectrophotometric measurement. All the samples were prepared in double quantities. The results were considered acceptable if the individual repeated test data did not have a relative deviation of more than 2% with respect to their mean value.
(30) b) Determination of Chlorine
(31) For said purpose, samples of the pyridyl iron complexes used for the purpose of the present invention, about 30 mg-50 mg, were precisely weighed in a 100 ml glass beakers in dry-box under nitrogen flow. 2 g of sodium carbonate (Na.sub.2CO.sub.3) were added and, outside the dry-box, 50 ml of MilliQ water. It was brought to the boiling on the hot plate, under magnetic stirring, for about 30 minutes. It was left to cool, then 1/5 diluted sulfuric acid (H.sub.2SO.sub.4) was added, until acid reaction and was then titrated with 0.1 N silver nitrate (AgNO.sub.3) with a potentiometric titrator.
(32) c) Determination of Carbon, Hydrogen and Nitrogen
(33) The determination of carbon, hydrogen and nitrogen, in the pyridyl iron complexes used for the purpose of the present invention, as well as in the ligands used for the purpose of the present invention, was carried out through a Carlo Erba automatic analyzer Mod. 1106.
(34) .sup.13C-NMR and .sup.1H-NMR Spectra
(35) The .sup.13C-NMR and .sup.1H-NMR spectra were recorded through a nuclear magnetic resonance spectrometer mod. Bruker Avance 400, using deuterated tetrachloroethylene (C.sub.2D.sub.2Cl.sub.4) at +103° C., and hexamethyldisilazane (HDMS) as internal standard. For this purpose, polymeric solutions were used with concentrations equal to 10% by weight with respect to the total weight of the polymeric solution.
(36) The microstructure of the polyisoprenes obtained [i.e. cis-1,4(%) and 3,4(%) unit content] was determined through the analysis of the aforesaid spectra based on the indications reported in literature by Ricci G. et al, “Macromolecules” (2009), Vol. 42(23), pp. 9263-9267, mentioned above.
(37) For that purpose:
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%3,4=[B/(2A+B)]×100 wherein B represents the area of the peaks related to the two olefinic protons with a 3,4 structure, and A represents the area of the peak related to the only olefinic proton of the unit with a cis-1,4 structure;
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(40) I.R. Spectra
(41) The I.R. (FT-IR) spectra were recorded through Thermo Nicolet Nexus 670 and Bruker IFS 48 spectrophotometers.
(42) The I.R. (FT-IR) spectra of the polyisoprenes obtained were determined by the analysis of polymeric films on potassium bromide (KBr) tablets, said films being obtained through the deposition of a solution in hot 1,2-dichlorobenzene of the polymer to be analyzed. The concentration of the polymeric solutions analyzed was equal to 10% by weight with respect to the total weight of the polymeric solution.
(43) Determination of the Molecular Weight
(44) The determination of the molecular weight (MW) of the polyisoprenes obtained was carried out through GPC (“Gel Permeation Chromatography”), using the Waters® Alliance® GPC/V 2000 System by Waters Corporation which uses two detection lines: Refractive Index (RI) and Viscometer operating under the following conditions: two PLgel Mixed-B columns; solvent/eluent: o-dichlorobenzene (Aldrich); flow rate: 0.8 ml/min; temperature: +145° C.; molecular mass calculation: Universal Calibration method.
(45) The weight-average molecular weight (M.sub.w) and the Polydispersion Index (PDI) corresponding to the ratio M.sub.w/M.sub.n (M.sub.n=number-average molecular weight) are reported.
(46) Differential Scanning calorimetry (DSC)
(47) Differential Scanning calorimetry analysis, for the purpose of determining the glass transition temperature (T.sub.g) of the polymers obtained, was carried out through a Perkin Elmer Pyris differential scanning calorimeter. For that purpose, 5 mg of polymer were analyzed, with a scanning speed ranging from +1° C./min to +20° C./min, in an inert nitrogen atmosphere.
Example 1
Synthesis of Ligand Having Formula (L1)
(48) ##STR00005##
(49) In a 250 ml flask, 2-acetylpyridine (9.1 g, 75 mmoles) and some drops of formic acid were added to a solution of o-toluidine (8 g, 75 mmoles) in methanol (100 ml): the mixture obtained was left, under stirring, at ambient temperature, for 48 hours. Subsequently, the solvent was removed through vacuum evaporation and the residue obtained was purified through elution on a silica gel chromatography column [eluent: mixture of heptane/ethyl acetate in ratio of 99/1 (v/v)], obtaining 6.5 g of a light yellow oil (yield=40%) corresponding to the ligand having formula (L1).
(50) Molecular weight (MW): 210.28.
(51) Elementary analysis [found (calculated for C.sub.14H.sub.14N.sub.2)]: C: 80.00% (79.97%); H: 6.77% (6.71%); N: 13.41% (13.32%).
(52) .sup.1H-NMR (CDCl.sub.3, δ ppm) 8.70 (m, 1H, HPy), 8.41 (m, 1H HPy), 7.80 (td, 1H, HPy), 7.39 (dt, 1H, HPy), 7.27-7.18 (m, 2H, Ph), 7.02 (m, 1H, Ph), 6.69 (d, 1H, Ph), 2.30 (s, 3H, N═C—CH.sub.3), 2.10 (s, 3H, Ph-CH.sub.3).
Example 2
Synthesis of Ligand Having Formula (L2)
(53) ##STR00006##
(54) In a 250 ml flask, 2-acetylpiridine (3.78 g; 31.1 mmoles) and p-toluenesulfonic acid monohydrate (0.15 g; 0.81 mmoles) were added to a solution of 2-iso-propylaniline (4.20 g; 31.1 mmoles) in toluene (20 ml): the mixture obtained was heated under reflux, for 2 hours. Subsequently, the solvent was removed through vacuum evaporation and the residue obtained was purified through vacuum distillation, obtaining 5.89 g of an orange oil (yield=79%) corresponding to the ligand having formula (L2).
(55) Molecular weight (MW): 238.33.
(56) Elementary analysis [found (calculated for C.sub.16H.sub.18N.sub.2)]: C: 80.17% (80.63%); H: 7.80% (7.61%); N: 11.91% (11.75%).
(57) .sup.1H-NMR (CDCl.sub.3, δ ppm) 8.71 (d, 1H), 8.37 (d, 1H), 7.81 (t, 1H), 7.38 (m, 2H), 7.22 (t, 1H), 7.15 (t, 1H), 6.67 (d, 1H), 3.05 (sept, 1H), 2.39 (s, 3H), 1.23 (d, 6H).
Example 3
Synthesis of FeCl.SUB.3.(L1) [Sample MG213]
(58) ##STR00007##
(59) In a 100 ml flask, to a solution of the ligand having formula (L1) (293 mg; 1.39 mmoles), obtained as described in Example 1, in toluene (20 ml), iron (III) chloride (FeCl.sub.3) (225 mg; 1.39 mmoles; molar ratio L1/Fe=1) was added: the mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The supernatant was then removed through evaporation at reduced pressure and the residue obtained was washed with heptane (2×15 ml) and vacuum dried, at ambient temperature, obtaining 396 mg of a brown solid product corresponding to the complex FeCl.sub.3(L1), equal to a 76% conversion with respect to the iron (III) chloride (FeCl.sub.3) loaded.
(60) Molecular weight (MW): 372.48.
(61) Elementary analysis [found (calculated for C.sub.14H.sub.14Cl.sub.3FeN.sub.2)]: C: 45.00% (45.14%), H: 3.69% (3.79%), N: 7.69% (7.52%), Cl: 28.96% (28.55%), Fe: 15.09% (14.99%).
Example 4
Synthesis of FeCl.SUB.3.(L2) [Sample MG208]
(62) ##STR00008##
(63) In a 100 ml flask, to a solution of the ligand having formula (L2) (514 mg; 2.16 mmoles), obtained as described in Example 2, in toluene (20 ml), iron (III) chloride (FeCl.sub.3) (350 mg; 2.16 mmoles; molar ratio L2/Fe=1) was added: the mixture obtained was maintained, under stirring, at ambient temperature, for 3 hours. The supernatant was then removed through evaporation at reduced pressure and the residue obtained was washed with heptane (2×15 ml) and vacuum dried, at ambient temperature, obtaining 821 mg of a red solid product corresponding to the complex FeCl.sub.3(L2), equal to a 95% conversion with respect to the iron (III) chloride (FeCl.sub.3) loaded.
(64) Molecular weight (MW): 400.53.
(65) Elementary analysis [found (calculated for C.sub.16H.sub.18Cl.sub.3FeN.sub.2)]: C: 48.09% (47.97%), H: 4.71% (4.53%), N: 6.65% (6.99%), Cl: 25.96% (26.55%), Fe: 14.08% (13.94%).
Example 5
Synthesis of FeCl.SUB.2.(L1) [Sample MG215]
(66) ##STR00009##
(67) In a 100 ml flask, to a solution of the ligand having formula (L1) (527 mg; 2.51 mmoles), obtained as described in Example 1, in toluene (20 ml), iron (II) chloride (FeCl.sub.2) (319 mg; 2.51 mmoles; molar ratio L1/Fe=1) was added: the mixture obtained was maintained, under stirring, at +100° C., for 3 hours. The supernatant was then removed through evaporation at reduced pressure and the residue obtained was washed with heptane (2×15 ml) and vacuum dried, at ambient temperature, obtaining 521 mg of a light blue solid product corresponding to the complex FeCl.sub.2(L1), equal to a 62% conversion with respect to the iron (II) chloride (FeCl.sub.2) loaded.
(68) Molecular weight (MW): 337.03
(69) Elementary analysis [found (calculated for C.sub.14H.sub.14Cl.sub.2FeN.sub.2)]: C: 49.10% (49.89%), H: 4.38% (4.19%), N: 8.21% (8.31%), Cl: 21.42% (21.04%), Fe: 16.82% (16.57%).
Example 6
Synthesis of FeCl.SUB.2.(L2) [sample MG212]
(70) ##STR00010##
(71) In a 100 ml flask, to a solution of the ligand having formula (L2) (540 mg; 2.27 mmoles), obtained as described in Example 2, in toluene (20 ml), iron (II) chloride (FeCl.sub.2) (288 mg; 2.27 mmoles; molar ratio L2/Fe=1) was added: the mixture obtained was maintained, under stirring, at +100° C., for 3 hours. The supernatant was then removed through evaporation at reduced pressure and the residue obtained was washed with heptane (2×15 ml) and vacuum dried, at ambient temperature, obtaining 665 mg of a light blue solid product corresponding to the complex FeCl.sub.2(L2), equal to a 80% conversion with respect to the iron (II) chloride (FeCl.sub.2) loaded.
(72) Molecular weight (MW): 365.08.
(73) Elementary analysis [found (calculated for C.sub.16H.sub.18Cl.sub.2FeN.sub.2)]: C: 52.12% (52.64%), H: 4.65% (4.96%), N: 7.26% (7.67%), Cl: 19.02% (19.42%), Fe: 15.04% (15.30%).
Example 7 (ZG189)
(74) 2 ml of isoprene equal to about 1.36 g were placed in a 25 ml test tube. Subsequently, 14 ml of toluene were added and the temperature of the solution thus obtained was brought to +20° C. Then, methylaluminoxane (MAO) in toluene solution (0.315 ml; 5×10.sup.−4 moles, equal to about 0.029 g) was added and, subsequently, the FeCl.sub.2(L1) complex [sample MG215] (1.7 ml of toluene solution at a concentration of 2 mg/ml; 1×10.sup.−5, equal to about 3.37 mg) obtained as described in Example 5. Everything was kept under magnetic stirring, at ambient temperature, for 5 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 1.36 g of polyisoprene for a conversion equal to 100%, having a mainly alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
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(76)
Example 8 (ZG188)
(77) 2 ml of isoprene equal to about 1.36 g were placed in a 25 ml test tube. Subsequently, 13.82 ml of toluene were added and the temperature of the solution thus obtained was brought to +20° C. Then, methylaluminoxane (MAO) in toluene solution (0.315 ml; 5×10.sup.−4 moles, equal to about 0.029 g) was added and, subsequently, the FeCl.sub.2(L2) complex [sample MG212] (1.87 ml of toluene solution at a concentration of 2 mg/ml; 1×10.sup.−5, equal to about 3.74 mg) obtained as described in Example 6. Everything was kept under magnetic stirring, at ambient temperature, for 10 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 1.36 g of polyisoprene for a conversion equal to 100%, having a mainly alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
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(79)
Example 9 (IP294)
(80) 5 ml of isoprene equal to about 3.4 g were placed in a 100 ml test tube. Subsequently, 31.3 ml of toluene were added and the temperature of the solution thus obtained was brought to −10° C. Then, methylaluminoxane (MAO) in toluene solution (0.13 ml; 2×10.sup.−4 moles, equal to about 0.012 g) was added and, subsequently, the FeCl.sub.2(L2) complex [sample MG212] (3.6 ml of toluene solution at a concentration of 2 mg/ml; 2×10.sup.−5, equal to about 7.3 mg) obtained as described in Example 6. Everything was kept under magnetic stirring, at ambient temperature, for 240 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 2.49 g of polyisoprene for a conversion equal to 73.2%, having an alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
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Example 10 (IP295)
(83) 5 ml of isoprene equal to about 3.4 g were placed in a 100 ml test tube. Subsequently, 31.3 ml of heptane were added and the temperature of the solution thus obtained was brought to +25° C. Then, methylaluminoxane (MAO) in toluene solution (0.13 ml; 2×10.sup.−4 moles, equal to about 0.012 g) was added and, subsequently, the FeCl.sub.2(L2) complex [sample MG212] (3.6 ml of toluene solution at a concentration of 2 mg/ml; 2×10.sup.−5, equal to about 7.3 mg) obtained as described in Example 6. Everything was kept under magnetic stirring, at ambient temperature, for 360 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 3.4 g of polyisoprene for a conversion equal to 100%, having an alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
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(85)
Example 11 (IP205/A)
(86) 2 ml of isoprene equal to about 1.36 g were placed in a 25 ml test tube. Subsequently, 13.82 ml of toluene were added and the temperature of the solution thus obtained was brought to +20° C. Then, methylaluminoxane (MAO) in toluene solution (0.315 ml; 5×10.sup.−4 moles, equal to about 0.029 g) was added and, subsequently, the FeCl.sub.3(L1) complex [sample MG213] (1.87 ml of toluene solution at a concentration of 2 mg/ml; 1×10.sup.−5, equal to about 3.74 mg) obtained as described in Example 3. Everything was kept under magnetic stirring, at ambient temperature, for 5 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 1.36 g of polyisoprene for a conversion equal to 100%, having an alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
(87)
(88)
Example 12 (IP206/A)
(89) 2 ml of isoprene equal to about 1.36 g were placed in a 25 ml test tube. Subsequently, 13.72 ml of toluene were added and the temperature of the solution thus obtained was brought to +20° C. Then, methylaluminoxane (MAO) in toluene solution (0.315 ml; 5×10.sup.−4 moles, equal to about 0.029 g) was added and, subsequently, the FeCl.sub.3(L2) complex [sample MG208] (2 ml of toluene solution at a concentration of 2 mg/ml; 1×10.sup.−5, equal to about 4 mg) obtained as described in Example 4. Everything was kept under magnetic stirring, at ambient temperature, for 5 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 1.36 g of polyisoprene for a conversion equal to 100%, having an alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
(90)
(91)
Example 13 (IP271)
(92) 2 ml of isoprene equal to about 1.36 g were placed in a 25 ml test tube. Subsequently, 13.9 ml of heptane were added and the temperature of the solution thus obtained was brought to +20° C. Then, methylaluminoxane (MAO) in toluene solution (0.063 ml; 1×10.sup.−4 moles, equal to about 0.058 g) was added and, subsequently, the FeCl.sub.3(L2) complex [sample MG208] (2 ml of toluene solution at a concentration of 2 mg/ml; 1×10.sup.−5, equal to about 4 mg) obtained as described in Example 4. Everything was kept under magnetic stirring, at ambient temperature, for 20 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 0.544 g of polyisoprene for a conversion equal to 40%, having an alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
(93)
(94)
Example 14 (IP269)
(95) 2 ml of isoprene equal to about 1.36 g were placed in a 25 ml test tube. Subsequently, 13.4 ml of toluene were added and the temperature of the solution thus obtained was brought to +20° C. Then, tri-iso-butylaluminum (TIBA) (0.07 ml; 3×10.sup.−4 moles, equal to about 0.0595 g) was added and, subsequently, the FeCl.sub.3(L2) complex [sample MG208] (1.87 ml of toluene solution at a concentration of 2 mg/ml; 1×10.sup.−5, equal to about 3.74 mg) obtained as described in Example 4. Everything was kept under magnetic stirring, at ambient temperature, for 2880 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 0.481 g of polyisoprene for a conversion equal to 35.4%, having an alternating cis-1,4/3,4 structure: further characteristics of the process and of the polyisoprene obtained are reported in Table 1.
(96)
(97)
Example 15
Synthesis of the Catalytic System AlEt.SUB.2.Cl/Nd(OCOC.SUB.7.H.SUB.15.).SUB.3./Al(.SUP.i.Bu).SUB.3
(98) The catalytic system AlEt.sub.2Cl/Nd(OCOC.sub.7H.sub.15).sub.3/Al(.sup.iBu).sub.3 was prepared as described in Ricci G. et al, “Polymer Communications” (1987), Vol. 28, Issue 8, pp. 223-226, mentioned above.
(99) For that purpose, neodymium 2-ethylhexanoate [Nd(OCOC.sub.7H.sub.15).sub.3] (2.38×10.sup.−4 moles; 0.136 grams) and heptane (9.6 ml) were placed into a 25 ml test tube. The solution thus obtained, was kept, under stirring, at ambient temperature, for 1 hour. Subsequently, diethylaluminum chloride (AlEt.sub.2Cl) in heptane solution [7.5×10.sup.−3 moles; 0.09 grams; 0.47 ml of a heptane solution 1/5 (v/v)] was added, drop by drop: a white/light blue suspension was formed which was kept, under vigorous stirring, for 15 minutes. Subsequently, tri-iso-butylaluminum (TIBA) (7.1×10.sup.−3 moles; 1.42 grams; 1.8 ml) was added: everything was kept, under stirring, at ambient temperature for 24 hours, obtaining a solution of the catalytic system AlEt.sub.2Cl/Nd(OCOC.sub.7H.sub.15).sub.3/Al(.sup.iBu).sub.3 having a concentration of neodymium equal to 0.02 M.
Example 16 (Comparative)
Synthesis of Polyisoprene Having a Mainly Cis-1,4 Structure
(100) 2 ml of isoprene equal to about 1.36 g were placed into a 25 ml test tube. Subsequently 15.5 ml of heptane were added and the temperature of the solution thus obtained was brought to +0° C. Then the catalytic system AlEt.sub.2Cl/Nd(OCOC.sub.7H.sub.15).sub.3/Al(.sup.iBu).sub.3 (0.25 ml of heptane solution having a concentration of neodymium equal to 0.02 M; 5×10.sup.−6 moles) was added, obtained as described in Example 15. Everything was kept under magnetic stirring, at +0° C., for 60 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 1.03 g of polyisoprene for a conversion equal to 75.7%, having a mainly cis-1,4 structure 97%).
(101)
Example 17 (Comparative)
Synthesis of Polyisoprene Having a Mainly Syndiotactic 3,4 Structure
(102) The polyisoprene having a mainly syndiotactic 3,4 structure was obtained by operating as described in Ricci G. et al, “Journal of Molecular Catatalysis A: Chemical” (2003), 204-205, pp. 287-293, mentioned above
(103) For that purpose, 2 ml of isoprene equal to about 1.36 g and toluene (10.9 ml) were placed into a 25 ml test tube. The temperature of the solution thus obtained was brought to −30° C., then methylaluminoxane (MAO) in toluene solution (3.8 ml; 6×10.sup.−3 moles, equal to about 0.348 g) was added and, subsequently the complex FeCl.sub.2(bipy).sub.2 (1.3 ml of toluene solution at a concentration of 2 mg/ml; 6×10.sup.−6 moles, equal to about 2.6 mg). Everything was kept under magnetic stirring, at −30° C., for 80 minutes. The polymerization was then quenched by adding 2 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 40 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 1.233 g of polyisoprene for a conversion equal to 90.5%, having a mainly syndiotactic 3,4 structure 80%).
(104)
Example 18 (Comparative)
Synthesis of Polyisoprene with a Perfectly Alternating Cis-1,4-Alt-3,4 Structure
(105) The polyisoprene with a perfectly alternating cis-1,4-alt-3,4 structure was obtained by operating as described in Ricci G. et al, “Macromolecules” (2009), Vol. 42(23), pp. 9263-9267, mentioned above.
(106) For that purpose, 5 ml of isoprene equal to about 3.4 g were placed in a 50 ml test tube. Subsequently, 6.6 ml of toluene were added and the temperature of the solution thus obtained was brought to +22° C. Then, methylaluminoxane (MAO) in toluene solution (0.63 ml; 1×10.sup.−3 moles, equal to about 0.058 g) was added and, subsequently, the CoCl.sub.2(P.sup.nPrPh.sub.2).sub.2 complex (5.9 ml of toluene solution at a concentration of 1 mg/ml; 1×10.sup.−5, equal to about 5.9 mg). Everything was kept under stirring, at ambient temperature, for 140 minutes. The polymerization was then quenched by adding 5 ml of methanol containing some drops of hydrochloric acid. The polymer obtained was then coagulated by adding 60 ml of a methanol solution containing 4% of Irganox® 1076 antioxidant (Ciba) obtaining 2.26 grams of polyisoprene for a conversion equal to 66.5%, having a perfectly alternating cis-1,4-alt-3,4 structure.
(107)
(108) TABLE-US-00001 TABLE 1 Polymerization of isoprene with catalytic systems comprising pyridyl iron complexes Al/Fe Time Conversion cis-1,4 3.4 M.sub.w T.sub.g Example (molar ratio) (min) (%) (%) (%) (g × mol.sup.−1) M.sub.w/M.sub.n (° C.) 7 50 5 100 58.5 41.5 260800 1.8 −29.7 8 50 10 100 59.3 40.7 244700 2.0 −31.9 9 10 240 73.2 57.2 42.8 315700 1.7 −30.2 10 10 360 100 58.2 41.8 120600 2.1 −29.6 11 50 5 100 59.1 40.9 369900 1.9 −29.3 12 50 5 100 57.7 42.3 355600 2.0 −29.9 13 10 20 40 56.1 43.9 113700 2.2 −29.0 14 30 2880 35.4 56.2 43.8 142900 2.1 −28.1
(109) TABLE-US-00002 TABLE 2 Attribution of the different peaks present in the olefinic zone of the .sup.13C-NMR spectrum