PROCESS FOR PREPARING POLYCARBONTE AND CATALYTIC SYSTEM USED

Abstract

The present invention relates to a process for preparing polycarbonate comprising copolymerizing an epoxy compound and carbon dioxide (CO.sub.2) in the presence of a catalytic system comprising: at least one catalyst selected from complexes of a transition metal; at least one co-catalyst selected from ionic compounds, as well as to a catalytic system comprising: at least one catalyst selected from complexes of a transition metal; at least one co-catalyst selected from ionic compounds.

Claims

1. Process for preparing polycarbonate comprising copolymerizing an epoxy compound and carbon dioxide (CO.sub.2) in the presence of a catalytic system comprising: at least one catalyst selected from complexes of a transition metal having general formula (I): ##STR00053## wherein: E represents a metal atom selected from chromium, manganese, iron, cobalt, nickel, aluminum, preferably chromium, cobalt; R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9 and R.sub.10, identical or different, represent a hydrogen atom; or are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.12, optionally containing heteroatoms; optionally substituted aryl groups; optionally substituted heteroaryl groups; optionally substituted cycloalkyl groups; optionally substituted heterocyclic groups; or R.sub.6 and R.sub.7 and/or R.sub.9 and R.sub.10, may optionally be linked together to form, together with the other atoms to which they are linked, a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which may optionally be substituted with linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups, optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, trialkyl- or triarylsilyl groups, dialkyl- or diaryl-amine groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated C.sub.1-C.sub.20 alkoxy groups, preferably C.sub.2-C.sub.10, optionally substituted aryloxy groups, optionally substituted thioalkoxy or thioaryloxy groups, cyano groups, said cycle optionally containing heteroatoms selected from the group consisting of oxygen, sulfur, nitrogen, silicon, phosphorus, selenium, oxygen, and nitrogen; Y represents a halogen anion such as a fluoride anion, a chloride anion, a bromide anion, an iodide anion, preferably a chloride anion, a bromide anion; or is selected from inorganic anions such as azide anion, hydroxide anion, amide anion, perchlorate anion, chlorate anion, sulfate anion, phosphate anion, nitrate anion, preferably an azide anion; or is selected from organic anions selected from the group consisting of C.sub.1-C.sub.20 alcoholate anion, C.sub.1-C.sub.20 thioalcoholate anion, C.sub.1-C.sub.30 carboxylate anion, C.sub.1-C.sub.30 alkyl- or dialkyl-amide anion; Z represents a divalent organic radical having general formula (Ill), (IV) or (V): ##STR00054## wherein: R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15 and R.sub.16, identical or different, represent a hydrogen atom; or are selected from linear or branched, saturated or unsaturated C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.12, optionally containing heteroatoms; optionally substituted aryl groups; optionally substituted heteroaryl groups; optionally substituted cycloalkyl groups; optionally substituted heterocyclic groups; or R.sub.11 and R.sub.12 in general formula (III) or in general formula (IV), or R.sub.11 and R.sub.13 in general formula (IV), or R.sub.11 and R.sub.15 or R.sub.11 and R.sub.16 in general formula (V), may optionally be linked together to form together with the other atoms to which they are linked, a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which may optionally be substituted with linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, trialkyl- or trialyl-silyl groups, dialkyl or diaryl-amine groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkoxyl groups, preferably C.sub.2-C.sub.10, optionally substituted aryloxy groups, optionally substituted thioalkoxy or thioaryloxy groups, cyano groups, said cycle optionally containing heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorous, selenium, preferably oxygen, nitrogen; at least one co-catalyst selected from ionic compounds having general formula (II): ##STR00055## wherein: M represents a metal atom selected from phosphorus, arsenic, antimony, bismuth, preferably phosphorus; R.sub.1, R.sub.2, R.sub.3 and R.sub.4, identical or different, represent a hydrogen atom; or represent a halogen atom such as fluorine, chlorine, bromine, preferably fluorine, bromine; or are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.12, optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, said optionally substituted heteroaryl groups being optionally in the cationic form, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, said optionally substituted heterocyclic groups being optionally in the cationic form; or R.sub.1 and R.sub.2 and/or R.sub.2 and R.sub.3 and/or R.sub.3 and R.sub.4 and/or R.sub.4 and R.sub.1, may optionally be linked together to form together with the other atoms to which they are linked a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which may optionally be substituted with linear or branched, saturated or unsaturated C.sub.1-C.sub.20 alkyl groups, optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, trialkyl- or trialyl-silyl groups, dialkyl- or diaryl-amine groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkoxy groups, preferably C.sub.2-C.sub.10, optionally substituted aryloxy groups, thioalkoxy or thioaryloxyl groups, cyano groups, said cycle optionally containing heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorus, selenium, preferably oxygen, nitrogen; X.sup. represents a halogen anion such as a fluoride anion, a chloride anion, a bromide anion, an iodide anion, preferably a chloride anion, a bromide anion; or is selected from inorganic anions such as azide anion, perchlorate anion, chlorate anion, sulfate anion, phosphate anion, nitrate anion, hexafluorophosphate anion, tetrafluoroborate anion; or is selected from organic anions such as benzenesulfonate anion, toluenesulfonate anion, dodecylsulfate anion, octylphosphate anion, dodecylphosphate anion, octadecylphosphate anion, phenylphosphate anion, tetraphenylborate anion; preferably a chloride anion, a bromide anion, an azide anion, a tetrafluoroborate anion, a sulfate anion; provided that at least three of R.sub.1, R.sub.2, R.sub.3 and R.sub.4, are different from hydrogen.

2. Process for preparing polycarbonate according to claim 1, wherein said epoxy compound is selected from: C.sub.2-C.sub.20 alkylene oxides, optionally substituted with one or more halogen atoms or with one or more alkoxy groups; C.sub.4-C.sub.20 cycloalkylene oxides, optionally substituted with one or more halogen atoms or with one or more alkoxy groups; C.sub.8-C.sub.20 styrene oxides, optionally substituted with one or more halogen atoms or with one or more alkoxy, alkyl or aryl groups.

3. Process for preparing polycarbonate according to claim 1, wherein said epoxy compound is selected from ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene monoxide, 1,2-epoxy-7-octene, epifluorhydrin, epichlorhydrin, epibromhydrin, iso-propyl glycidyl ether, butyl glycidyl ether, tent-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, cyclopentene oxide, cyclohexene oxide, cycloctene oxide, cyclododecane oxide, -pinene oxide, 2,3-epoxynorbornene, limonene oxide, dieldrin, 2,3-epoxypropylbenzene, styrene oxide, phenylpropylene oxide, stilbene oxide, chlorostilbene oxide, dichlorostilbene oxide, 1,2-epoxy-3-phenoxypropane, benzyloxymethyl oxirane, glycidylmethylphenyl ethers, chlorophenyl-2,3-epoxypropyl ethers, epoxypropyl methoxyphenyl ethers, biphenyl glycidyl ethers, glycidyl naphtyl ethers, or mixtures thereof; preferably cyclohexene oxide, propylene oxide.

4. Process for preparing polycarbonate according to claim 1, wherein said process is carried out in the presence of at least one organic solvent selected from: aliphatic hydrocarbons such as pentane, octane, decane, cyclohexane, or mixtures thereof; aromatic hydrocarbons such as benzene, toluene, xylene, or mixtures thereof; halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, ethylchloride, trichloroethane, 1-chloropropane, 2-chloropropane, 1-chlorobutane, 2-chlorobutane, chlorobenzene, bromobenzene, or mixtures thereof; or mixtures thereof; preferably 1,2-dichloromethane; said organic solvent being used in volume ratio with respect to said at least one epoxy compound ranging from 0:100 to 99:1, preferably ranging from 0:100 to 90:1.

5. Process for preparing polycarbonate according to claims 1, wherein said at least one epoxy compound acts as a solvent.

6. Process for preparing polycarbonate according to claim 1, wherein: said catalytic system and said at least one epoxy compound are used in a molar ratio ranging from 1:100 to 1:100000, preferably ranging from 1:1000 to 1:10000; and/or in said catalytic system said at least one catalyst selected from transition metal complexes having general formula (I) and said at least one co-catalyst selected from ionic compounds having general formula (II) are used in a molar ratio ranging from 100:1 to 1:100, preferably ranging from 2:1 to 1:2, more preferably being 1:1.

7. (Currently amended I) Process for preparing polycarbonate according to claim 1, wherein said process is carried out; at a temperature ranging from 20 C. to 250 C., preferably ranging from 40 C. to 160 C.; and/or at a pressure ranging from 1 atm to 100 atm, preferably ranging from 2 atm to 60 atm; and/or for a time ranging from 30 minutes to 30 hours, preferably from 1.5 hours to 26 hours.

8. Catalytic system comprising: at least one catalyst selected from complexes of a transition metal having general formula (I): ##STR00056## wherein: E represents a metal atom selected from chromium, manganese, iron, cobalt, nickel, aluminum, preferably chromium, cobalt; R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9 and R.sub.10, identical or different, represent a hydrogen atom; or are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.12, optionally containing heteroatoms; optionally substituted aryl groups; optionally substituted heteroaryl groups; optionally substituted cycloalkyl groups; optionally substituted heterocyclic groups; or R.sub.6 and R.sub.7 and/or R.sub.9 and R.sub.10, may optionally be linked together to form, together with the other atoms to which they are linked, a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which may optionally be substituted with linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups, optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, trialkyl- or triarylsilyl groups, dialkyl- or diaryl-amine groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated C.sub.1-C.sub.20 alkoxy groups, preferably C.sub.2-C.sub.10, optionally substituted aryloxy groups, optionally substituted thioalkoxy or thioaryloxy groups, cyano groups, said cycle optionally containing heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorus, selenium, preferably oxygen, nitrogen; Y represents a halogen anion such as a fluoride anion, a chloride anion, a bromide anion, an iodide anion, preferably a chloride anion, a bromide anion; or is selected from inorganic anions such as azide anion, hydroxide anion, amide anion, perchlorate anion, chlorate anion, sulfate anion, phosphate anion, nitrate anion, preferably an azide anion; or is selected from organic anions such as C.sub.1-C.sub.20 alcoholate anion, C.sub.1-C.sub.20 thioalcoholate anion, C.sub.1-C.sub.30 carboxylate anion, C.sub.1-C.sub.30 alkyl- or dialkyl-amide anion; Z represents a divalent organic radical having general formula (Ill), (IV) or (V): ##STR00057## wherein: R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15 and R.sub.16, identical or different, represent a hydrogen atom; or are selected from linear or branched, saturated or unsaturated C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.12, optionally containing heteroatoms; optionally substituted aryl groups; optionally substituted heteroaryl groups; optionally substituted cycloalkyl groups; optionally substituted heterocyclic groups; or R.sub.11 and R.sub.12 in general formula (III) or in general formula (IV), or R.sub.11 and R.sub.13 in general formula (IV), or R.sub.11 and R.sub.15 or R.sub.11 and R.sub.16 in general formula (V), may optionally be linked together to form together with the other atoms to which they are linked, a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which may optionally be substituted with linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, trialkyl- or trialyl-silyl groups, dialkyl or diaryl-amine groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkoxyl groups, preferably C.sub.2-C.sub.10, optionally substituted aryloxy groups, optionally substituted thioalkoxy or thioaryloxy groups, cyano groups, said cycle optionally containing heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorous, selenium, preferably oxygen, nitrogen; at least one co-catalyst selected from ionic compounds having general formula (II): ##STR00058## wherein: M represents a metal atom selected from phosphorus, arsenic, antimony, bismuth, preferably phosphorus; R.sub.1, R.sub.2, R.sub.3 and R.sub.4, identical or different, represent a hydrogen atom; or represent a halogen atom such as fluorine, chlorine, bromine, preferably fluorine, bromine; or are selected from linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkyl groups, preferably C.sub.1-C.sub.12, optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, said optionally substituted heteroaryl groups being optionally in the cationic form, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, said optionally substituted heterocyclic groups being optionally in the cationic form; or R.sub.1 and R.sub.2 and/or R.sub.2 and R.sub.3 and/or R.sub.3 and R.sub.4 and/or R.sub.4 and R.sub.1, may optionally be linked together to form together with the other atoms to which they are linked a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which may optionally be substituted with linear or branched, saturated or unsaturated C.sub.1-C.sub.20 alkyl groups, optionally containing heteroatoms, optionally substituted aryl groups, optionally substituted heteroaryl groups, optionally substituted cycloalkyl groups, optionally substituted heterocyclic groups, trialkyl- or trialyl-silyl groups, dialkyl- or diaryl-amine groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated, C.sub.1-C.sub.20 alkoxy groups, preferably C.sub.2-C.sub.10, optionally substituted aryloxy groups, thioalkoxy or thioaryloxyl groups, cyano groups, said cycle optionally containing heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorus, selenium, preferably oxygen, nitrogen; X.sup. represents a halogen anion such as a fluoride anion, a chloride anion, a bromide anion, an iodide anion, preferably a chloride anion, a bromide anion; or is selected from inorganic anions such as azide anion, perchlorate anion, chlorate anion, sulfate anion, phosphate anion, nitrate anion, hexafluorophosphate anion, tetrafluoroborate anion; or is selected from organic anions such as benzenesulfonate anion, toluenesulfonate anion, dodecylsulfate anion, octylphosphate anion, dodecylphosphate anion, octadecylphosphate anion, phenylphosphate anion, tetraphenylborate anion; preferably a chloride anion, a bromide anion, an azide anion, a tetrafluoroborate anion, a sulfate anion; provided that at least three of R.sub.1, R.sub.2, R.sub.3 and R.sub.4, are different from hydrogen.

Description

EXAMPLES

[0086] Reagents and Materials

[0087] The list below reports the reagents and materials used in the following examples of the invention, any pre-treatments thereof and their manufacturer: [0088] cyclohexene oxide (Aldrich): purity 98%, distilled over calcium hydride (CaH.sub.2) in an inert atmosphere; [0089] propylene oxide (Aldrich): purity 99,5%, distilled over calcium hydride (CaH.sub.2) in an inert atmosphere; [0090] dichloromethane (CH.sub.2Cl.sub.2) (Aldrich) maintained at reflux temperature for 4 hours and distilled over calcium hydride (CaH.sub.2); [0091] tetraphenylphosphonium chloride (TPPCI) (Aldrich): 98%, recrystallized twice from a dichloromethane mixture (CH.sub.2Cl.sub.2) (Aldrich)/diethylether (C.sub.2H.sub.5).sub.2O (Aldrich) (1/10, v/v); [0092] triphenyl(4-pyridinylmethyl)phosphonium chloride hydrochloride (UHFFA) (Aldrich): 98%, recrystallized twice from a dichloromethane mixture (CH.sub.2Cl.sub.2) (Aldrich)/diethylether (C.sub.2H.sub.5).sub.2O (Aldrich) (1/10, v/v); [0093] triphenyl(2-pyridinylmethyl)phosphonium chloride hydrochloride (FAO) (Aldrich): 98%, recrystallized twice from a dichloromethane mixture (CH.sub.2Cl.sub.2) (Aldrich)/diethylether (C.sub.2H.sub.5).sub.2O (Aldrich) (1/10, v/v); [0094] carbon dioxide (CO.sub.2) (Rivoira): pure, 99.8%, used as such; [0095] N,N-bis(3,5-di-tert-butyl salicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] (Aldrich): used as such; [0096] silver perchlorate (AgClO.sub.4) (anhydrous) (Aldrich): used as such; [0097] acetonitrile (CH.sub.3CN) (anhydrous) (Aldrich): pure, 99.8%, used as such; [0098] sodium azide (NaN.sub.3) (Aldrich): pure, 99.5%, used as such; [0099] diethylether (C.sub.2H.sub.5).sub.2O (Aldrich): used as such; [0100] magnesium sulfate (MgSO.sub.4) (Merck): pure, 99.5%, used as it is; [0101] o-phenylenediamine (Aldrich): used as such; [0102] 3,5-di-tent-butylsalicylaldehyde (Aldrich): used as such; [0103] methanol (MeOH) (anhydrous) (Aldrich): pure, 99.8%, used as such; [0104] formic acid (HCOOH) (Aldrich): 95-97%, used as such; [0105] sodium chloride (NaCl) (Aldrich): pure, 99%, used as such; [0106] chromium(II) chloride (CrCl.sub.2) (Aldrich): 95%, used as such; [0107] tetrahydrofuran (THF) (anhydrous) (Aldrich): used as such; [0108] ammonium chloride (NH.sub.4C1) (Merck): pure, 99.9%, used as such; [0109] hydrochloric acid in 37% aqueous solution (Merck): used as such; [0110] acetone [(CH.sub.3).sub.2O] (Aldrich): used as such; [0111] deuterated methylene chloride (CD.sub.2Cl.sub.2) (Merck): used as such.

[0112] Elementary Analysis

[0113] a) Determination of Carbon, Hydrogen, Nitrogen, Chromium and Phosphorus

[0114] The determination of carbon, hydrogen, nitrogen, chromium and phosphorus in the compounds synthesized in the following examples, was carried out through a Carlo Erba automatic analyzer Mod. 1106.

[0115] NMR Spectra

[0116] The NMR spectra of the compounds synthesized in the following examples were acquired with an NMR Bruker Avance 400 spectrometer.

[0117] For that purpose, about 10 mg of the sample to be examined were dissolved in about 0.8 ml of CD.sub.2Cl.sub.2 (deuterated methylene chloride) directly in the glass tube used for the measurement. The chemical shift scale was calibrated in relation to the signal of the dichloromethane set to 5.30 ppm. The experimental parameters used were as follows: [0118] 128 scans; [0119] 90 pulse; [0120] delay: 2 s, +4.5 s, of acquisition time; [0121] spectral amplitude: 7200 Hz.

[0122] Differential Scanning calorimetry (DSC)

[0123] Differential Scanning calorimetry, for the purpose of determining the glass transition temperature (T.sub.g) of the polycarbonates obtained, was carried out through a Perkin Elmer Pyris differential scanning calorimeter. For that purpose, 5 mg of polycarbonate were analyzed, with a scanning speed ranging from 1 C./min to 20 C./min, in an inert nitrogen atmosphere.

[0124] Determination of the Molecular Weight

[0125] The determination of the molecular weight (M.sub.w) of the polycarbonates 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: [0126] two PLgel Mixed-B columns; [0127] solvent/eluent: o-dichlorobenzene (Aldrich); [0128] flow rate: 0.8 ml/min; [0129] temperature: 145 C.; [0130] molecular mass calculation: Universal Calibration method.

[0131] The number average molecular weight (M.sub.n), the weight average molecular weight (M.sub.w) and the polydispersion index (PDI) are reported (M.sub.w/M.sub.n ratio).

Example 1

Synthesis of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) azide [Cr(Salen)N.SUB.3.]

[0132] ##STR00050##

[0133] 2 g (3.16 mmoles) of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] and 0.65 g (3.16 mmoles) of anhydrous silver perchlorate (AgClO.sub.4) were dissolved, respectively, in 120 ml (in a 200 ml two-neck flask) and in 30 ml (in a 500 ml two-neck flask) of anhydrous acetonitrile (CH.sub.3CN), under nitrogen flow (N.sub.2), at ambient temperature (25 C.). The solution of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] obtained was then dripped, in about 30 minutes, into the solution of silver perchlorate (AgClO.sub.4) obtained: the reaction mixture obtained was left, under stirring, at ambient temperature (25 C.), for one night. Subsequently, the reaction mixture was filtered in order to separate the precipitated silver chloride (AgCl) and, after filtration, 0.62 g (9.48 mmoles) of sodium azide (NaN.sub.3) were added: the whole was left, under stirring, at ambient temperature (25 C.), for one night, for the purpose of promoting the slow dissolution of sodium azide (NaN.sub.3) in the acetonitrile (CH.sub.3CN). Subsequently, the mixture obtained was diluted with 150 ml of diethyl ether [(C.sub.2H.sub.5).sub.2O], then washed with water (3100 ml) obtaining an aqueous phase and an organic phase that were separated through a separatory funnel. The organic phase obtained was anhydrified on magnesium sulfate (MgSO.sub.4), filtered and the residual solvent was removed, under vacuum, obtaining 2.1 g of a green solid product (yield 88%) corresponding to N,N-bis(3,5-di-tert-butyl salicylidene)-1,2-cyclohexanediamine chromium(III) azide [Cr(Salen)N.sub.3].

[0134] Elementary analysis [found (calculated for C.sub.36H.sub.52N.sub.5O.sub.2Cr): C 66.31% (67.68%); H 7.94% (8.20%); N 9.87% (10.96%).

Example 2

Synthesis of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-benzodiamine (SalaphenH.SUB.2.)

[0135] ##STR00051##

[0136] In a 500 ml two-neck flask, 2.0 g (18.5 mmoles) of o-phenylenediamine and 8.67 g (37.0 mmoles) of 3,5-di-tent-butyl-salicylaldehyde were dissolved in 200 ml of anhydrous methanol (MeOH). A few drops (about 0.7 ml) of concentrated formic acid (HCOOH) were added to the solution obtained and the mixture was then refluxed for about 3 hours: the precipitation of a yellow-orange solid was observed. The progress of the reaction was observed through thin layer chromatography (TLC). At the end of the reaction, the solid obtained was separated through filtration, washed with cold anhydrous methanol (MeOH), subsequently dissolved in 20 ml of dichloromethane (CH.sub.2Cl.sub.2) and washed with water (2100 ml) and subsequently with a saturated sodium chloride solution (NaCl) (2100 ml) obtaining an aqueous phase and an organic phase that were separated through a separatory funnel. The organic phase obtained was anhydrified on magnesium sulfate (MgSO.sub.4), filtered and the residual solvent was removed, under vacuum, obtaining 7.5 g of an orange solid product (yield 75%) corresponding to N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine (SalaphenH.sub.2).

[0137] .sup.1H NMR (CD.sub.2Cl.sub.2, 600 MHz); (ppm) 8,71 (s, CHN, 2H), 7.46-7.27 (m, 8H), 1.44 (s, 18H), 1.33 (s, 18H).

Example 3

Synthesis of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-benzodiaminechromium(III) chloride [Cr(Salaphen)Cl]

[0138] ##STR00052##

[0139] In a 200 ml two-neck flask, 0.5 g (0.924 mmoles) of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-benzodiamine (SalaphenH.sub.2) obtained as described in Example 2 and 0.125 g (0.996 mmoles) of chromium(II) chloride (CrCl.sub.2), were dissolved, under nitrogen flow (N.sub.2), in 50 ml of anhydrous tetrahydrofuran (THF). The solution obtained was left, under stirring, at ambient temperature (25 C.), for 24 hours, under nitrogen flow (N.sub.2) and, subsequently, for another 24 hours, in air. The mixture obtained was diluted with 50 ml of diethyl ether [(C.sub.2H.sub.5).sub.2O], then extracted with a saturated solution of ammonium chloride (NH.sub.4Cl) (3100 ml) and subsequently with a saturated solution of sodium chloride (NaCl) (280 ml) obtaining an aqueous phase and an organic phase that were separated through a separatory funnel. The organic phase obtained was anhydrified on magnesium sulfate (MgSO.sub.4), filtered and the residual solvent was removed, under vacuum, obtaining 0.466 g of a green microcrystalline powder (yield 82%) corresponding to N,N-bis(3,5-di-tert-butyl salicylidene)-1,2-benzodiaminechromium(III) chloride [Cr(Salaphen)Cl].

[0140] Elementary analysis [found (calculated for C.sub.36H.sub.46N.sub.2O.sub.2CrCl): C 68.47% (69.05%); H 7.72% (7.40%); N 4.28% (4.47%).

[0141] .sup.1H NMR (CDCl.sub.3, 400 MHz); (ppm) 8.87 (s, CHN, 2H), 7.46-7.14 (m, 8H), 1.44 (s, 18H), 1.33 (s, 18H).

Examples 4-9

[0142] Preparation of polycyclohexenecarbonate (variable pressure)

[0143] A 250 ml steel autoclave was sanitized with thorough washing with acetone [(CH.sub.3).sub.2O] and anhydrous methanol (MeOH) and subsequently maintained, under vacuum, at 80 C., for 12 hours.

[0144] In the meantime, in a dry box, 0.073 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] and 0.049 mg (0.115 mmoles) of triphenyl(4-pyridinylmethyl)phosphonium chloride hydrochloride (UHFFA) were weighed in a Schlenk flask and, subsequently, 5 ml of dichloromethane (CH.sub.2Cl.sub.2) were added: the mixture obtained was left, under stirring, at ambient temperature (25 C.), for 1 hour. The solvent was then removed, under vacuum, and 25 ml of cyclohexene oxide were added to the catalytic system obtained: the reaction mixture obtained was left, under stirring, at ambient temperature (25 C.), for 15 minutes and subsequently inserted, under vacuum, into an autoclave at the working temperature of 80 C. Once inserted into the autoclave, the reaction mixture was maintained, under stirring for 2 minutes and, subsequently, carbon dioxide (CO.sub.2) was added at a pressure of 30 atm. The polymerization reaction was carried out for 3.5 hours, at the end of which, the pressure inside the autoclave had dropped to 15 atm. Subsequently, the autoclave was cooled to 30 C. and the pressure was brought to 1 atm. The semisolid viscous solution obtained was collected from the autoclave and purified through dissolution in dichloromethane (CH.sub.2Cl.sub.2) (20 ml) and precipitation with 100 ml of a methanol (MeOH)/hydrochloric acid (HCI) (9/1, v/v) solution. The precipitated solid was collected by filtration, dried at reduced pressure, at ambient temperature (25 C.) and finely ground.

[0145] Examples 5-9 were carried out operating under the same conditions described above with the only difference being the use of different catalytic systems (i.e. different catalysts and co-catalysts). In particular, [0146] Example 5: 0.073 g (0.115 mmoles) of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] and 0.043 g (0.115 mmoles) of tetraphenylphosphonium chloride (TPPCI); [0147] Example 6: 0.073 g (0.115 mmoles) of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] and 0.049 g (0.115 mmoles) of triphenyl(2-pyridinylmethyl)phosphonium chloride hydrochloride (FAO); [0148] Example 7: 0.037 g (0.057 mmoles) of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] and 0.025 g (0.057 mmoles) of triphenyl(4-pyridinylmethyl)phosphonium chloride hydrochloride (UHFFA); [0149] Example 8 (invention): 0.073 g (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexanediamine chromium(III) azide [Cr(Salen)N.sub.3] obtained as described in Example 1 and 0.049 g (0.115 mmoles) of triphenyl(4-pyridinylmethyl)phosphonium chloride hydrochloride (UHFFA); [0150] Example 9 (invention): 0.073 g (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexanediamine chromium(III) azide [Cr(Salen)N.sub.3] obtained as described in Example 1 and 0.043 g (0.115 mmoles) of tetraphenylphosphonium chloride (TPPCI).

[0151] The polycyclohexenecarbonate obtained from each example, was then characterized through (DSC) (Differential Scanning calorimetry) and GPC (Gel Permeation Chromatography): the results obtained are reported in Table 3 wherein they are reported in the following order: the Example number, the type and the amount in mmoles of catalyst, the type and the amount in mmoles of co-catalyst, the polymerization temperature (T) in Celsius degrees, the amount of polymer recovered (yield) in grams, the number average molecular weight (M.sub.n) in g/mole, the weight average molecular weight (M.sub.w) in g/mole, the polydispersion index (PDI) (M.sub.w/M.sub.n ratio) and the glass transition temperature (T.sub.g) in Celsius degrees.

TABLE-US-00003 TABLE 3 Catalyst Co-catalyst T Yield M.sub.n M.sub.w T.sub.g Example (mmoles) (mmoles) ( C.) (g) (g/mole) (g/mole) M.sub.w/M.sub.n ( C.) 4 Cr(Salen)Cl UHFFA 80 17.3 11120 13010 1.17 111 (0.115) (0.115) 5 Cr(Salen)Cl TPPCI 80 6.2 11764 22446 1.91 70 (0.115) (0.115) 6 Cr(Salen)Cl FAO 80 12.5 10149 7717 1.22 117 (0.115) (0.115) 7 Cr(Salen)Cl UHFFA 80 17.1 8721 19362 2.22 70 (0.057) (0.057) 8 Cr(Salen)N.sub.3 UHFFA 80 14.9 9060 10238 1.13 119 (0.115) (0.115) 9 Cr(Salen)N.sub.3 TPPCI 80 7.1 4810 5510 1.15 115 (0.115) (0.115)

Examples 10-11

[0152] Preparation of polycyclohexenecarbonate (constant pressure)

[0153] A 250 ml steel autoclave was sanitized with thorough washing with acetone [(CH.sub.3).sub.2O] and anhydrous methanol (MeOH) and subsequently maintained, under vacuum, at 80 C., for 12 hours.

[0154] In the meantime, in a dry box, 0.073 g (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] obtained as described in Example 3 and 0.049 g (0.115 mmoles) of triphenyl(4-pyridinylmethyl)-phosphonium chloride hydrochloride (UHFFA) were weighed in a Schlenk flask and, subsequently, 5 ml of dichloromethane (CH.sub.2Cl.sub.2) were added: the mixture obtained was left, under stirring, at ambient temperature (25 C.), for 1 hour. The solvent was then removed, under vacuum, and 25 ml of cyclohexene oxide were added to the catalytic system obtained. The reaction mixture obtained was left, under stirring, at ambient temperature (25 C.), for 15 minutes and then inserted, under vacuum, into an autoclave at the working temperature of 80 C. Once inserted into the autoclave, the reaction mixture was maintained, under stirring for 2 minutes and, subsequently, carbon dioxide (CO.sub.2) was added at a pressure of 30 atm: the pressure was kept constant through a system of flow meter valves for the whole polymerization duration. The polymerization reaction was carried out for 3.5 hours, at the end of which the autoclave was cooled to 30 C. and the pressure was brought to 1 atm.

[0155] The semisolid viscous solution obtained was collected from the autoclave and purified through dissolution in dichloromethane (CH.sub.2Cl.sub.2) (20 ml) and precipitation with 100 ml of a methanol (MeOH)/hydrochloric acid (HCl) (9/1, v/v) solution. The precipitated solid was collected by filtration, dried at reduced pressure, at ambient temperature (25 C.) and finely ground.

[0156] Example 11 was carried out operating under the same operating conditions with the following differences: use of a different catalytic system (i.e. different catalyst and co-catalyst), co-polymerization temperature, i.e. 120 C. instead of 80 C. In particular: [0157] Example 11: 0.073 g (0.115 mmoles) of N,N-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine chromium(III) chloride [Cr(Salen)Cl] and 0.049 g (0.115 mmoles) of triphenyl(4-pyridinylmethyl)phosphonium chloride hydrochloride (UHFFA).

[0158] The polycyclohexenecarbonate obtained from each example was then characterized through (DSC) (Differential Scanning calorimetry) and GPC (Gel Permeation Chromatography): the results obtained are reported in Table 4 wherein they are reported in the following order: : the Example number, the type and the amount in mmoles of catalyst, the type and the amount in mmoles of co-catalyst, the polymerization temperature (T) in Celsius degrees, the amount of polymer recovered (yield) in grams, the number average molecular weight (M.sub.n) in g/mole, the weight average molecular weight (M.sub.w) in g/mole, the polydispersion index (PDI) (M.sub.w/M.sub.n ratio) and the glass transition temperature (T.sub.g) in Celsius degrees.

TABLE-US-00004 TABLE 4 Co- Catalyst catalyst T Yield M.sub.n M.sub.w T.sub.g Example (mmoles) (mmoles) ( C.) (g) (g/mole) (g/mole) M.sub.w/M.sub.n ( C.) 10 Cr(Salaphen)Cl UHFFA 80 8.43 5590 6916 1.24 116 (0.115) (0.115) 11 Cr(Salen)Cl UHFFA 120 7.84 7517 8368 1.11 118 (0.115) (0.115)

Examples 12-19

[0159] Preparation of polypropylene carbonate (variable pressure)

[0160] A 250 ml steel autoclave was sanitized with thorough washing with acetone [(CH.sub.3).sub.2O] and anhydrous methanol (MeOH) and subsequently maintained, under vacuum, at 80 C., for 12 hours.

[0161] In the meantime, in a dry box, 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] obtained as described in Example 3 and 0.025 mg (0.57 mmoles) of triphenyl(4-pyridinyl-methyl)phosphonium chloride hydrochloride (UHFFA) were weighed in a Schlenk flask and, subsequently, 5 ml of dichloromethane (CH.sub.2Cl.sub.2) were added: the mixture obtained was left, under stirring, at ambient temperature (25 C.), for 1 hour. The solvent was then removed, under vacuum, and 25 ml of propylene oxide were added to the catalytic system obtained: the reaction mixture obtained was left, under stirring, at ambient temperature (25 C.), for 15 minutes and subsequently inserted, under vacuum, into an autoclave at the working temperature of 80 C. Once inserted into the autoclave, the reaction mixture was maintained, under stirring for 2 minutes and, subsequently, carbon dioxide (CO.sub.2) was added at a pressure of 30 atm. The polymerization reaction was carried out for 24 hours, at the end of which, the pressure inside the autoclave had dropped to 18 atm. Subsequently, the autoclave was cooled to 30 C. and the pressure was brought to 1 atm.

[0162] The semisolid viscous solution obtained was collected from the autoclave and purified through dissolution in dichloromethane (CH.sub.2Cl.sub.2) (20 ml) and precipitation with 100 ml of a methanol (MeOH)/hydrochloric acid (HCl) (9/1, v/v) solution. The precipitated solid was collected by filtration, dried at reduced pressure, at ambient temperature (25 C.) and finely ground.

[0163] Examples 13-16 were carried out operating under the same conditions described above with the only difference being the use of different catalytic systems (i.e. different co-catalysts). In particular, [0164] Example 13: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.022 g (0.057 mmoles) of tetraphenylphosphonium chloride (TPPCI); [0165] Example 14: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.025 g (0.057 mmoles) of triphenyl(2-pyridinylmethyl)phosphonium chloride hydrochloride (FAO); [0166] Example 15: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.027 g (0.057 mmoles) of 3-(bromopropyltriphenyl)phosphonium bromide (BTPBr); [0167] Example 16: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.022 g (0.057 mmoles) of benzyltriphenylphosphonium chloriide (BTPCI); [0168] Example 17: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.026 g (0.057 mmoles) of 2-(aminobenzyl)triphenylphosphonium bromide (ABPBr); [0169] Example 18: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.026 g (0.057 mmoles) of (tent-butoxycarbonylmethyl)triphenylphosphonium bromide (BMPBr); [0170] Example 19: 0.074 mg (0.115 mmoles) of N,N-bis(3,5-di-tert-butyl-salicylidene)-1,2-benzodiamine chromium(III) chloride [Cr(Salaphen)Cl] and 0.024 g (0.057 mmoles) of (3-carboxylpropyl)triphenyl)phosphonium bromide (CPPBr).

[0171] The polypropylene carbonate obtained from each example, was then characterized through (DSC) (Differential Scanning calorimetry) and GPC (Gel Permeation Chromatography): the results obtained are reported in Table 5 wherein they are reported in the following order: the Example number, the type and the amount in mmoles of catalyst, the type and the amount in mmoles of co-catalyst, the conversion expressed as a percentage and determined with a NMR spectrum (.sup.1H-MNR) on the crude reaction product in order to determine the amount of propylene oxide converted in polypropylene carbonate, the selectivity expressed as a percentage and determined with a NMR spectrum (.sup.1H-MNR) on the crude reaction product in order to determine the amount of polypropylene carbonate obtained with respect to the amount of cyclic carbonate, the amount of ether linkages remained in the polypropylene carbonate after its purification expressed as a percentage and determined with a NMR spectrum (.sup.1H-MNR), the number average molecular weight (M.sub.n) in g/mole, the weight average molecular weight (M.sub.w) in g/mole, the polydispersion index (PDI) (M.sub.w/M.sub.n ratio) and the glass transition temperature (T.sub.g) in Celsius degrees.

TABLE-US-00005 TABLE 5 Co- Ether Catalyst catalyst Conversion Selectivity linkages M.sub.n M.sub.w T.sub.g Example (mmoles) (mmoles) (%) (%) (%) (g/mole) (g/mole) M.sub.w/M.sub.n ( C.) 12 Cr(Salaphen)Cl UHFFA 83 59 12 26660 32790 1.23 35 (0.115) (0.057) 13 Cr(Salaphen)Cl TPPCI 83 90 5 29400 33520 1.14 39 (0.115) (0.057) 14 Cr(Salaphen)Cl FAO 59 68 16 19500 20870 1.07 30 (0.115) (0.057) 15 Cr(Salaphen)Cl BTPBr 60 58 3 14400 16270 1.13 n.m. (0.115) (0.057) 16 Cr(Salaphen)Cl BTPCI 39 45 19 13300 14100 1.06 n.m. (0.115) (0.057) 17 Cr(Salaphen)Cl ABPBr 10 26 43 n.m. n.m. n.m. n.m. (0.115) (0.057) 18 Cr(Salaphen)Cl BMPBr 11 53 37 n.m. n.m. n.m. n.m. (0.115) (0.057) 19 Cr(Salaphen)Cl CPPBr 20 27 38 n.m. n.m. n.m. n.m. (0.115) (0.057) n.m.: not measured.