Process for preparing polypropylene carbonate

1 . Process for the preparation of polypropylene carbonate comprising the copolymerization of propylene oxide and carbon dioxide (CO 2 ) in the presence of a catalytic system comprising:

at least one catalyst selected from complexes of a transition metal having general formula (I):

wherein:

M represents a metal atom selected from the group consisting of chromium, manganese, iron, cobalt, nickel, and aluminum;

Y represents a halide anion; or it is selected from inorganic anions; or it is selected from organic anions;

R 1 represents a hydrogen atom; or it is selected from linear or branched, saturated or unsaturated, C 1 -C 20 alkyl groups, optionally containing heteroatoms, optionally substituted aryl groups, heteroaryl groups optionally substituted, the optionally substituted heteroaryl groups being optionally in cationic form, and cycloalkyl groups optionally substituted;

R 2 and R 3 , mutually identical or different, represent a hydrogen atom; or they are selected from linear or branched, saturated or unsaturated, C 1 -C 20 , alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triaryl-silyls groups optionally substituted;

or R 2 and R 3 are optionally bound together so as to form, together with the atoms to which they are bound, a saturated, unsaturated or aromatic cycle containing from 3 to 12 carbon atoms, optionally polycondensed, which are optionally substituted with linear or branched, saturated or unsaturated, C 1 -C 20 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triaryl-silyl groups, dialkyl- or diaryl-amine groups, linear or branched, saturated or unsaturated C 1 -C 20 alkoxy groups, aryloxy groups optionally substituted, thioalkoxy or thioaryloxy groups optionally substituted, cyano groups, the cycle optionally containing heteroatoms;

at least one co-catalyst selected from:

(a) ionic compounds having general formula (II):

wherein:

E represents an atom selected from the group consisting of phosphorus, arsenic, antimony, and bismuth;

R 4 , R 5 , R 6 and R 7 , mutually identical or different, represent a hydrogen atom; or they represent a halogen atom; or they are selected from the group consisting of linear or branched, saturated or unsaturated C 1 -C 20 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, the heteroaryl groups optionally substituted being optionally in the cationic form, cycloalkyl groups optionally substituted, and heterocyclic groups optionally substituted, the optionally substituted heterocyclic groups being optionally in the cationic form;

or R 4 and R 5 and/or R 5 and R 6 and/or R 6 and R 7 and/or R 7 and R 4 are optionally bound together so as to form together with the other atoms to which they are bound a saturated, unsaturated or aromatic cycle containing from 1 to 12 carbon atoms, which are linear or branched, saturated or unsaturated C 1 -C 20 alkyl groups optionally substituted, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triarylsilyl groups, dialkyl- or diaryl-amino groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated C 1 -C 20 alkoxy groups, aryloxy groups optionally substituted, thioalkoxy or thioaryloxy groups optionally substituted, cyano groups, the cycle optionally containing heteroatoms;

X − represents a halogen anion; or it is selected from inorganic anions; or it is selected from organic anions;

n is an integer between 1 and 4;

provided that at least three of R 4 , R 5 , R 6 and R 7 are different from hydrogen;

(b) ionic compounds having general formula (III):

wherein:

E represents an atom selected from phosphorus, arsenic, antimony, and bismuth;

R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 and R 15 , mutually identical or different, represent a hydrogen atom; or they are selected from linear or branched, saturated or unsaturated C 1 -C 20 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, the heteroaryl groups optionally substituted being optionally in cationic form, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, the optionally substituted heterocyclic groups being optionally in cationic form, trialkyl- or triaryl-silyl groups;

or R 8 and R 9 , and/or R 10 and R 11 , and/or R 11 and R 12 , and/or R 12 and R 13 , and/or R 13 and R 14 , and/or R 14 and R 15 are optionally bound together so as to form together with the other atoms to which they are bound a saturated, unsaturated or aromatic cycle containing from 2 to 12 carbon atoms, which are optionally substituted with linear or branched, saturated or unsaturated C 1 -C 20 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triaryl-silyl groups, dialkyl- or diaryl-amino groups, dialkyl- or diaryl-phosphine groups, linear or branched, saturated or unsaturated C 1 -C 20 alkoxy groups, aryloxy groups optionally substituted, thioalkoxy or thioaryloxy groups optionally substituted, cyano groups, the cycle optionally containing heteroatoms;

W represents a halogen atom; or it is selected from linear or branched, saturated or unsaturated C 1 -C 20 alkoxy groups, aryloxy groups optionally substituted, and oxylamine groups;

X − represents a halide anion; or it is selected from inorganic anions; or it is selected from organic anions; or it is selected from tetra-alkylborate anions optionally containing heteroatoms; tetra-arylborate anions optionally containing heteroatoms; and an azide anion;

a is an integer between 0 and 4;

b is an integer between 0 and 4;

c is 0 or 1;

provided that the sum a+b+c is equal to 4 and that at least one of a and b is different from 0; and

m is an integer between 1 and 4.

2 . Process for the preparation of polypropylene carbonate according to claim 1 , wherein the process is carried out in the presence of at least one organic solvent selected from: aliphatic hydrocarbons; aromatic hydrocarbons; halogenated hydrocarbons; or mixtures thereof.

3 . The process of claim 2 , wherein aliphatic hydrocarbons are selected from the group consisting of pentane, octane, decane, cyclohexane, and mixtures thereof;

wherein aromatic hydrocarbons are selected from the group consisting of benzene, toluene, xylene, and mixtures thereof; wherein halogenated hydrocarbons are selected from the group consisting of dichloromethane, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, ethylchloride, trichloroethane, 1-chloropropane, 2-chloropropane, 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, chlorobenzene, bromobenzene, or mixtures thereof; and mixtures thereof.

4 . The process of claim 3 , wherein the halogenated hydrocarbons is dichloromethane.

5 . Process for the preparation of polypropylene carbonate according to claim 1 , wherein the propylene oxide acts as a solvent.

6 . Process for the preparation of polypropylene carbonate according to claim 1 , wherein:

the catalytic system and the propylene oxide are used in a molar ratio between 1:100 and 1:100000; and/or

in the catalytic system, the at least one catalyst selected from complexes of a transition metal having general formula (I) and the at least one co-catalyst selected from ionic compounds having general formula (II) or general formula (III) are used in a molar ratio between 100:1 and 1:100.

7 . The process of claim 6 , wherein the catalytic system and the propylene oxide are used in a molar ratio between 1:1000 and 1:10000; and wherein the at least one catalyst and the at least one co-catalyst are used in a molar ratio between 2:1 and 1:2.

8 . Process for the preparation of polypropylene carbonate according to claim 1 , wherein the process is carried out;

at a temperature between 0° C. and 250° C.; and/or

at a pressure between 1 atm and 100 atm; and/or

for a time between 30 minutes and 48 hours.

9 . The process of claim 8 , wherein the temperature is between 10° C. and 120° C.; and/or the pressure is between 2 atm and 60 atm; and/or the time is between 2 hours and 30 hours.

10 . The process of claim 1 , wherein the halide anion of Y is selected from the group consisting of a fluoride anion, a chloride anion, a bromide anion, and an iodide anion; wherein the inorganic anion of Y is selected from the group consisting of azide anions, hydroxide anions, amide anions, a perchlorate anions, chlorate anions, sulfate anions, phosphate anions, and a nitrate anions; wherein the organic anions of Y are selected from the group consisting of C 1 -C 30 carboxylate anions; C 1 -C 20 alcoholate anions; C 1 -C 20 thioalcoholate anions; and an C 1 -C 30 alkyl or dialkyl-amide anion; wherein the C 1 -C 20 thioalcoholate anions are selected from the group consisting of thioethoxide anion, thiophenoxide anion; wherein the C 1 -C 30 alkyl or dialkyl-amide anion is selected from the group consisting of di-methyl-amide anion, di-iso-propylamide anion, diphenyl-amide anion; wherein the C 1 -C 20 alkoxy groups are selected from the group consisting of C 2 -C 10 alkoxy groups; wherein the heteroatoms of the cycle of R 2 and R 3 are selected from the group consisting of oxygen, sulfur, nitrogen, silicon, phosphorus, and selenium; wherein the heteroatoms the cycle of R 4 and R 5 and/or R 5 and R 6 and/or R 6 and R 7 and/or R 7 and R 4 are selected from the group consisting of oxygen, sulfur, nitrogen, silicon, phosphorus, and selenium; wherein E is phosphorus; wherein the halogen atom of R 4 , R 5 , R 6 and R 7 is selected from the group consisting of fluorine, chlorine, and bromine; wherein the halogen anion of X − of general formula (II) is selected from the group consisting of a fluoride anion, a chloride anion, a bromide anion, and an iodide anion; wherein the inorganic anions of X − of general formula (II) are selected from the group consisting of azide anion, perchlorate anion, chlorate anion, sulfate anion, phosphate anion, nitrate anion, hexafluorophosphate anion, and tetrafluoroborate anion; wherein the organic anions of X − of general formula (II) are selected from the group consisting of benzenesulfonate anion, toluenesulfonate anion, dodecylsulfate anion, octylphosphate anion, dodecylphosphate anion, octadecylphosphate anion, phenylphosphate anion, and tetraphenylborate anion; wherein n is an integer of 1 or 2; wherein the C 1 -C 20 alkyl groups of R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 and R 15 are C 1 -C 12 alkyl groups; wherein the heteroatoms of the cycle of R 8 and R 9 , and/or R 10 and R 11 , and/or R 11 and R 12 , and/or R 12 and R 13 , and/or R 13 and R 14 , and/or R 14 and R 15 are selected from the group consisting of oxygen, sulfur, nitrogen, silicon, phosphorus, and selenium; wherein the halogen atom of W is selected from the group consisting of chlorine, bromine, fluorine, and iodine; wherein the C 1 -C 20 alkoxy groups of W are C 1 -C 10 alkoxy groups; wherein the halide anion of X − of general formula (III) is selected from the group consisting of a fluoride anion, a chloride anion, a bromide anion, and an iodide anion; wherein the inorganic anions of X − of general formula (III) are selected from the group consisting of azide anion, perchlorate anion, chlorate anion, sulfate anion, phosphate anion, nitrate anion, hexafluorophosphate anion, and tetrafluoroborate anion; wherein the organic anions of X − of general formula (III) is selected from the group consisting of benzenesulfonate anion, toluenesulfonate anion, dodecylsulfate anion, octyl phosphate anion, dodecylphosphate anion, octadecylphosphate anion, and phenylphosphate anion; wherein the tetra-alkylborate anions of X − of general formula (III) are selected from the group consisting of oxygen and nitrogen; wherein the heteroatoms of the tetra-arylborate anions of X − of general formula (III) are selected from the group consisting of oxygen and nitrogen; wherein a is an integer from 1 to 3; wherein b is an integer from 1 to 4; wherein c is 0; and wherein m is 1 or 2.

11 . The process of claim 10 , wherein the C 1 -C 30 carboxylate anions are selected from the group consisting of an acetate anion, a butyrate anion, 2-ethyl-hexanoate anions, acrylate anions, methyl methacrylate anions, benzoate anions, and trifluoroacetate anions; wherein C 1 -C 20 alcoholate anions are selected from the group consisting of methoxide anions, ethoxide anion, tert-butoxide anions, phenoxide anions, 2,4,6-trimethylphenoxide anions, and 4-tert-butyl-phenoxide anions; wherein the C 1 -C 20 thioalcoholate anions are selected from the group consisting of thioethoxide anions, thiophenoxide anions, C 1 -C 30 alkyl or dialkyl-amide anions, di-iso-propylamide anions, and diphenyl-amide anions; wherein the halide anion of Y is selected from the group consisting of chloride anion and a bromide anion; wherein the inorganic anions are azide anions; wherein heteroatoms are selected from the group consisting of oxygen and nitrogen; wherein the heteroatoms the cycle of R 2 and R 3 are selected from the group consisting of oxygen and nitrogen; wherein the heteroatoms the cycle of R 4 and R 5 and/or R 5 and R 6 and/or R 6 and R 7 and/or R 7 and R 4 are selected from the group consisting of oxygen and nitrogen; wherein the halogen atom of R 4 , R 5 , R 6 and R 7 is selected from the group consisting of fluorine and bromine; wherein the halogen anion of X − of general formula (II) is selected from the group consisting of the chloride anion and the bromide anion; wherein the inorganic anions of X − of general formula (II) are selected from the group consisting of azide anion, sulfate anion, and tetrafluoroborate anion; wherein the heteroatoms of the cycle of R 8 and R 9 , and/or R 10 and R 11 , and/or R 11 and R 12 , and/or R 12 and R 13 , and/or R 13 and R 14 , and/or R 14 and R 15 are selected from the group consisting of oxygen and nitrogen; wherein the halogen atom of W is selected from the group consisting of chlorine and bromine; wherein the tetra-alkylborate anions of X − of general formula (III) are selected from the group consisting of oxygen and nitrogen; and wherein the halide anion of X − of general formula (III) is a chloride anion.

12 . The process of claim 11 , wherein the C 1 -C 30 alkyl or dialkyl-amide anion is di-methyl-amide anion.

13 . A transition metal complex having general formula (Ia):

wherein:

M represents a metal atom selected from the group consisting of chromium and cobalt;

Y′ represent an azide anion;

R 1 represents a hydrogen atom; or it is selected from the group consisting of linear or branched, saturated or unsaturated, C 1 -C 12 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, the heteroaryl groups optionally substituted being optionally in cationic form, cycloalkyl groups optionally substituted, and heterocyclic groups optionally substituted, the optionally substituted heterocyclic groups being optionally in cationic form;

R 2 and R 3 , mutually identical or different, represent a hydrogen atom; or they are selected from the group consisting of linear or branched, saturated or unsaturated, C 1 -C 12 , alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, and trialkyl- or triaryl-silyls groups optionally substituted;

or R 2 and R 3 may be optionally bound together so as to form, together with the atoms to which they are bound, a saturated, unsaturated or aromatic cycle containing from 3 to 12 carbon atoms, optionally polycondensed, which may be optionally substituted with linear or branched saturated, unsaturated or aromatic, optionally polycondensed, C 1 -C 12 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triaryl-silyl groups, dialkyl- or diaryl-amine groups, linear or branched, saturated or unsaturated C 2 -C 10 alkoxy groups, aryloxy groups optionally substituted, thioalkoxy or thioaryloxy groups optionally substituted, and cyano groups, the cycle optionally containing heteroatoms selected from the group of oxygen, sulfur, nitrogen, silicon, phosphorus, and selenium.

14 . The transition metal complex of claim 13 , wherein the heteroatoms of the cycle of R 2 and R 3 are selected from the group consisting of oxygen and nitrogen.

15 . Process for the preparation of a transition metal complex having

wherein:

M represents a metal atom selected from the group consisting of chromium, manganese, iron, cobalt, nickel, and aluminum;

R 1 represents a hydrogen atom; or it is selected from linear or branched, saturated or unsaturated, C 1 -C 20 alkyl groups, optionally containing heteroatoms, optionally substituted aryl groups, heteroaryl groups optionally substituted, the optionally substituted heteroaryl groups being optionally in cationic form, and cycloalkyl groups optionally substituted;

R 2 and R 3 , mutually identical or different, represent a hydrogen atom; or they are selected from linear or branched, saturated or unsaturated, C 1 -C 20 , alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triaryl-silyls groups optionally substituted;

or R 2 and R 3 are optionally bound together so as to form, together with the atoms to which they are bound, a saturated, unsaturated or aromatic cycle containing from 3 to 12 carbon atoms, optionally polycondensed, which are optionally substituted with linear or branched, saturated or unsaturated, C 1 -C 20 alkyl groups, optionally containing heteroatoms, aryl groups optionally substituted, heteroaryl groups optionally substituted, cycloalkyl groups optionally substituted, heterocyclic groups optionally substituted, trialkyl- or triaryl-silyl groups, dialkyl- or diaryl-amine groups, linear or branched, saturated or unsaturated C 1 -C 20 alkoxy groups, aryloxy groups optionally substituted, thioalkoxy or thioaryloxy groups optionally substituted, cyano groups, the cycle optionally containing heteroatoms; and

wherein Y″ represents a halide anion, comprising reacting at least one transition metal complex having general formula (IV):

in the presence of at least one organic solvent selected from the group consisting of halogenated solvents and alcohols with at least one hydrogen halide acid; wherein the mixture of the transition metal complex has general formula (IV) and the organic solvent:

a first aliquot of the at least one hydrogen halide acid is added and the mixture obtained is left to react, at a temperature between 30° C. and 70° C., for a time of between 3 hours and 7 hours; and subsequently

a second aliquot of the at least one hydrogen halide acid is added and the mixture obtained is left to react, at a temperature between 30° C. and 70° C., for a time of between 8 hours and 15 hours; and subsequently

a third aliquot of the at least one hydrogen halide acid is added and the mixture obtained is left to react, at a temperature between 30° C. and 70° C. for a time of between 18 hours and 30 hours.

16 . The process of claim 15 , wherein Y″ represents a fluoride anion, a chloride anion, a bromide anion, an iodide anion; wherein the halogenated solvents is selected from the group consisting of trichloromethane, dichloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, chlorobenzene, and mixtures thereof; wherein the alcohols with at least one hydrogen halide acid is selected from the group consisting of methanol, ethanol, iso-propanol, butanol, 1-octanol, and mixtures thereof; wherein the at least one hydrogen halide acid is selected from the group consisting of hydrochloric acid, hydrobromic acid, hydroiodic acid, hydrofluoric acid, and mixtures thereof; wherein the temperature of reacting of the first aliquot is between 40° C. and 60° C.; wherein the time of reacting of the first aliquot is between 4 hours and 6 hours; wherein the temperature of reacting of the second aliquot is between 40° C. and 60° C.; wherein the time of reacting of the second aliquot is between 10 hours and 13 hours; wherein the temperature of reacting of the third aliquot is between 40° C. and 60° C.; and wherein the time of reacting of the third aliquot is between 20 hours and 26 hours.

17 . The process of claim 16 , wherein the halogenated solvents is trichloromethane; wherein the alcohols is methanol; and wherein the at least one hydrogen halide acid is hydrochloric acid.