The present invention relates to the field of processes to prepare carbonyl-containing compounds, and more particularly cyclic carbonates that are mainly used as monomers to produce different biocompatible and biodegradable carbonyl-containing polymers.

BACKGROUND

Cyclic carbonates are a very intriguing and promising class of material that have been commercially available since the mid-1950’s. Since then, five membered cyclic carbonates have found numerous applications due to their biodegradability, high solvency, high boiling points (up to 240°C), high flash points (up to 160°C), low odour levels, low evaporation rates, and low toxicities. Moreover, the use of five membered cyclic carbonates as a solvent in degreasing, paint stripping, and cleaning applications has risen in the past few years. Cyclic carbonates such as 1,3-dioxolan-2-one, also named ethylene carbonate, and 4-methyl-1,3-dioxolan-2-one, also named propylene carbonate, are being utilized as electrolytes for lithium-ion batteries. Furthermore, propylene carbonate has also been studied as a carrier solvent for topically applied medications and cosmetics.

Although much can be said concerning the use of cyclic carbonates as inert media, their potential as reactive monomers for the preparation of innovative polymers such as polycarbonates, polyesters and polyurethanes, through ring-opening polymerization, is an emerging area or interest. Such polymers have been synthesised noticeably because of their biocompatibility and biodegradability for a large variety of applications, from isocyanate-free polyurethane adhesives to high-added-value polycarbonates for biomedical use or as polymer electrolytes for energy storage.

For instance, 1 ,3-dioxan-2-one, also named trimethylene carbonate (TMC) is the simplest 6-membered cyclic carbonate and it has been extensively studied, either as a lone monomer to synthesise poly(trimethylene carbonate) (polyTMC), or in combination with lactones (ex: glycolide, lactide) or functionalised cyclic carbonates to form different functional carbonyl-containing polymers. It has been noticeably studied because of the suitable biocompatibility and biodegradability of the resulting polycarbonates.

Three different type of reactions were firstly employed to obtain TMC in particular and cyclic carbonates in general which are (1) the utilization of phosgene or derivatives with diols, (2) the coupling of dioxide carbonate (CO2) with diols and (3) the coupling of CO2 with oxetanes.

However, phosgene is a highly toxic gas which use is problematic and whose usage, handling and storing are severely regulating in most countries. Although they are not a gas at ambient temperature, derivatives such as triphosgene, chloroformates or isocyanates are also very toxic (and flammable for some of them). The use of CO2 as a precursor (with diols or oxetanes) for making cyclic carbonates is a more sustainable but limited alternative. Because of unfavourable equilibria and the low reactivity of CO2, toxic and expensive catalysts (usually metallic) as well as high temperature and/or harsh pressure conditions are required to obtain average yields (40-60%), rendering this type of reaction industrially irrelevant.

On the other hand, the concept of depolymerising Bisphenol A-based Polycarbonate (BPA-PC) to obtain carbonyl-containing cyclic molecules can be encountered in recent scientific articles. lannone et al., ( J . of Mol. Cat. A, 426, 107-116, 2017) describes the depolymerisation of BPA-PC catalysed by nanoparticles of Zinc at 100 °C in tetrahydrofuran (THF) to obtain 5- and 6-membered cyclic carbonates, carbamates and ureas.

Do et ai, ( Polym , 143, 106-114, 2018) also discloses the depolymerisation of BPA-PC using 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) organic base as catalyst in 2-methyl tetrahydrofuran and under nitrogen atmosphere to obtain 5-membered cyclic carbonates.

In the process described in Guaranta et ai, ( ACS Omega, 3 (7), 7261-7268, 2018), the depolymerisation of BPA-PC is performed using 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) as catalyst, in THF and under nitrogen to obtain 5-membered cyclic carbonates.

A method to obtain cyclic carbonates from BPA-PC wastes using a thermally stable acid- base catalyst has also been recently developed (Jehanno et ai, ACS Macro Letters, 9 (4), 443-447, 2020). With this procedure, different nucleophiles were employed as reagent for the depolymerisation of BPA-PC to yield carbonyl-containing cyclic molecules and Bisphenol A (BPA) in high yields and purity. The reaction is performed in bulk, with a recyclable organocatalyst forms of equimolar quantities of TBD and methanesulfonic acid (MSA) (TBD: MSA) under high temperature (90 to 160 °C depending on the reagent employed) and inert atmosphere.

The use of BPA-PC as a reagent for the synthesis of cyclic carbonate is highly beneficial because of the simplicity and low cost of the methodology. This procedure combines the recycling of commodity polymer wastes and the easy production of high-added value monomers.

However, this method did not allow the production of TMC itself, but only derivatives thereof, while high temperatures and inert atmosphere are required. Thus, alternative methods to produce carbonyl-containing cyclic molecules, and more importantly TMC in good yields, from BPA-PC as reagent are necessary. Furthermore, it would be desirable that said methods could be extended to also produce carbonyl- containing linear molecules. Particularly important is the development of procedures which require milder reaction conditions and the use of readily available catalysts.

BRIEF DESCRIPTION OF THE INVENTION

The authors of the present invention have developed an innovative process to synthesize carbonyl-containing molecules, both cyclic carbonates such as TMC, as well as linear carbonates, from the recycling of BPA-PC wastes. The procedure can be considered sustainable, as it only uses non-toxic chemicals, employs plastic wastes as reagent and is performed at relatively low temperatures, without requiring inert atmosphere.

The depolymerisation of BPA-PC can be carried out with a wide variety of reagents as nucleophile, with the additional advantage of employing a readily available catalyst.

A significant advantage of the process depicted in the present invention is the use of an imidazole or a derivative thereof as catalyst in combination with an organic solvent since they allow the production of said carbonyl-containing compounds at low temperatures without requiring a protective atmosphere.

Furthermore, the reaction takes place fast and is unpredictably selective providing TMC with yields up to 90%. Thus, the main aspect of the present invention refers to a process for preparing carbonyl-containing compounds of formula (la), (lb) or (lc):

wherein:

Xi, X ₂ , X ₃ and X ₄ are independently selected from O, S and N(Rn);

R ₁ -R ₁₁ and Zi are independently selected from: hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; C ₅ -C ₁₀ cycloalkyl, optionally substituted with at least one C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl;

C ₅ -C ₁₀ heterocyclyl, optionally substituted with at least one C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl;

C ₆ -C ₁₀ aryl, optionally substituted with at least one C ₁ -C ₄ alkyl, at least one fluorinated or perfluorinated C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; C ₅ -C ₁₀ heteroaryl optionally substituted with at least one C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl; a (C ₅ -C ₇ )cycloalkyl (CrC ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl (CrC ₄ )alkyl, wherein the aryl is optionally substituted with at least one C1-C4 alkyl; a “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl;

-C(0)0Ri ₄ , wherein R _M is a CrCe alkyl, a Ce-Cio aryl or a (Ci-C ₄ )alkyl(Ce-Cio)aryl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl; or in the compounds of formula (la), Ri and R ₃ , or R ₄ and R ₅ when n is i, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl; in the compounds of formula (lb), Ri and R ₃ or R ₃ and R ₅ , and/or R ₄ and R ₇ or R ₄ and Rg, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Y is a single bond or a group -(CH ₂ ) -0-(CH ₂ ) _q -, wherein indexes p and q are independently selected from 0, 1 and 2; n is O oM; comprising the reaction of BPA-PC of formula (II): (II) wherein m is from 10 to 1000. with a reagent of formula (Ilia), (I lib) or (I lie):

H-X1-Z1

(lllc) wherein Xi, X2, X3, X4, Ri-Rio,Y _> Zi and n are as defined above; in the presence of a catalyst of formula (IV). or any tautomeric form thereof, wherein: Z and W are independently selected from C and N, provided that Z and W are not simultaneously N; Ri5, Ri ₆ , Ri7 and Ris are independently selected from H and a C1-C4 alkyl group, or Ri ₇ and Ris can form a C ₆ aryl group when Z is C; and in the presence of an organic solvent, and wherein the process is carried out at a temperature from 25 to 60°C.

DETAILED DESCRIPTION OF THE INVENTION

In the context of the present invention, the following terms found in the described formulas have the meaning indicated below:

The term “alkyl” refers to a group formed by a linear or branched hydrocarbon chain consisting of carbon and hydrogen atoms, which contains no unsaturation and is linked to the rest of the molecule through a single bond. Specific examples include, without limitation, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-pentyl, etc. C1-C6 and C1-C4 alkyl, when mentioned, refer to said group having between 1 and 6 carbon atoms, and between 1 and 4 carbon atoms, respectively.

The term "C2-6 alkenyl" refers to a linear or branched hydrocarbon chain consisting of carbon and hydrogen atoms having at least one double bond, and from 2 to 6 carbon atoms. In a preferred embodiment, they refer to linear hydrocarbons having a single double bond.

The term “C5-10 cycloalkyl” refers to a saturated or partially saturated mono- or bicyclic aliphatic group having between 3 and 7, preferably between 3 and 6 carbon atoms (“C3- C ₆ cycloalkyl”), which is bound to the rest of the molecule by means of a single bond, including for example and in a non-limiting sense, cyclopropyl, cyclohexyl or cyclopentyl.

The term “C5-C10 heterocyclyl” refers to a monocyclic or bicyclic system which can be partially or fully saturated containing 5 to 10, preferably 5 or 6, ring atoms containing one or more, specifically one, two or three ring heteroatoms independently selected from N, O, and S, preferably one or two, and the remaining ring atoms being carbon. Examples of heterocyclyl groups include, but are not limited to, pyrrolidine, piperidine, tetrahydropyridine, piperazine, morpholine, thiomorpholine, azepane, diazepane, tetrahydrofuran, tetrahydropyran, octahydro-pyrrolopyrazine.

The term “C6-10 aryl” refers to an aromatic group having between 6 and 10, more preferable having 6 carbon atoms, comprising 1 or 2 aromatic nuclei, including for example and in a non-limiting sense, phenyl, biphenyl or naphthyl. Preferably, aryl refers to phenyl (Ph) or biphenyl.

The term “C ₅ -C ₁₀ heteroaryl” refers to a monocyclic or bicyclic system which is aromatic and contains 5 to 10, preferably 5 or 6, ring atoms containing one or more, specifically one, two or three ring heteroatoms independently selected from N, O, and S, preferably one or two, and the remaining ring atoms being carbon. Examples of such heteroaryl include, but are not limited to, thiophene, furan, pyrrole, thiazole, oxazole, isothiazole, isoxazole, imidazole, pyrazole, triazole, oxadiazole, thiadiazole, tetrazole, tetrazole oxide, oxadiazolone, pyridine, pyrimidine, pyrazine, dihydroindolone, benzimidazole, isoindole, benzothiazole, benzofuran, indole, purine, quinolone, isoquinoline. The term “(C ₅ -Cio)cycloalkyl(Ci-C ₄ )alkyl, refers to a C ₅ -C ₁₀ cycloalkyl group as defined above which is attached to the rest of the molecule through a C ₁ -C ₄ alkyl group as defined above. Preferably, the (Ci-C ₄ )alkyl(C ₅ -Cio)cycloalkyl is a (Ci-C ₃ )alkyl(C ₅ -C ₆ )cycloalkyl. Examples of these groups include cyclohexylmethyl, cyclohexylethyl and cyclohexylpropyl. The term “(C ₆ -Cio)aryl(Ci-C ₄ )alkyl” refers to a C ₆ -C ₁₀ aryl group as defined above which is attached to the rest of the molecule through a C ₁ -C ₄ alkyl group as defined above. Preferably, the (C ₆ -Cio)aryl(Ci-C ₄ )alkyl is a (C ₆ )aryl(Ci-C ₃ )alkyl. Examples of these groups include benzyl, phenylethyl, phenylpropyl, naphthylmethyl. Preferably, it refers to benzyl (Bn). The term “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl” refers to a C ₅ -C ₁₀ heteroaryl group as defined above which is attached to the rest of the molecule through a C ₁ -C ₄ alkyl group as defined above. Preferably, the (C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl is a (C ₅ -C ₆ )heteroaryl (Ci-C ₃ )alkyl.

The term “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl” refers to a C ₆ -C ₁₀ aryl group as defined above which is attached to the rest of the molecule through a C ₂ -C ₆ alkenyl group as defined above. Preferably, the (C ₆ -Cio)aryl(C ₂ -Ce)alkenyl is (C ₆ )aryl(C ₂ -C ₄ )alkenyl. Examples of these groups include (Ce)aryl(C ₂ )alkenyl (styryl), (Cio)aryl(C ₂ )alkenyl (vinylnaphthalene). Preferably, it refers to styryl.

The term “halogen” refers to F, Cl, Br or I.

As used herein, the terms “optional” or “optionally” means that the subsequent described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase “optionally substituted” for an alkyl group means that the alkyl group may or may not be substituted and that the description includes both substituted and unsubstituted alkyl groups.

As mentioned above, the main aspect of the present invention relates to a process for preparing carbonyl-containing cyclic compounds of formula (la), (lb) or (lc): wherein:

Xi, X2, X3 and X4 are independently selected from O, S and N(Rn);

R ₁ -R ₁₁ and Zi are independently selected from: hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; C5-C10 cycloalkyl, optionally substituted with at least one C1-C4 alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C1-C4 alkyl;

C5-C10 heterocyclyl, optionally substituted with at least one C1-C4 alkyl, hydroxyl, halogen or amine group N(Ri2)(Ri3) wherein R10 and Rn are independently selected from H and C1-C4 alkyl; C ₆ -C1 ₀ aryl, optionally substituted with at least one C1-C4 alkyl, at least one fluorinated or perfluorinated C1-C4 alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₀ and R11 are independently selected from H and C1-C4 alkyl;

C5-C1 ₀ heteroaryl optionally substituted with at least one C1-C4 alkyl, hydroxyl, halogen or amine group N(Ri2)(Ri ₃ ) wherein R1 ₀ and Rn are independently selected from H and C1-C4 alkyl; a (C ₅ -C ₇ )cycloalkyl (CrC ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl (CrC ₄ )alkyl, wherein the aryl is optionally substituted with at least one C1-C4 alkyl; a “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl, wherein the aryl is optionally substituted with at least one C1-C4 alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl;

-C(0)0Ri4, wherein RM is a CrCe alkyl, a Ce-Cio aryl or a (Ci-C4)alkyl(Ce-Cio)aryl; and wherein any of the CrCe alkyl and C2-C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C1-C4 alkyl; or in the compounds of formula (la), Ri and R ₃ , or R4 and R5 when n is 1, each pair together can form a C5-C7 cycloalkyl or C5-C ₆ heterocyclyl group optionally substituted with C1-C4 alkyl; in the compounds of formula (lb), Ri and R ₃ or R ₃ and R5, and/or R4 and R7 or R4 and Rg, together can form a C5-C7 cycloalkyl or C5-C ₆ heterocyclyl group optionally substituted with C1-C4 alkyl.

Y is a single bond or a group -(CH ₂ ) -0-(CH ₂ ) _q -, wherein indexes p and q are independently selected from 0, 1 and 2; n is 0 or 1 ; comprising the reaction of BPA-PC of formula (II): m is from 10 to 1000; with a compound of formula (Ilia), (Nib) or (lllc):

H-X1-Z1

(lllc) wherein Xi, X ₂ , X ₃ , X ₄ , R1-R11 ,Y, Zi and n are as defined above; in the presence of a catalyst of formula (IV): or any tautomeric form thereof; wherein: Z and W are independently selected from C and N, provided that Z and W are not simultaneously N;

Ri ₅ , R ₁₆ , Ri ₇ and Ris are independently selected from H and a C ₁ -C ₄ alkyl group or Ri ₇ and Ris can form a C ₆ aryl group when Z is C; and in the presence of an organic solvent, and wherein the process is carried out at a temperature from 25 to 60°C.

In a particular embodiment, Xi, X ₂ , X ₃ and X ₄ are independently selected from O, - NH, N(CI-C ₄ alkyl) and -N(C ₆ aryl), wherein the C ₆ aryl is optionally substituted with at least one C ₁ -C ₄ alkyl, a fluorinated or perfluorinated C ₁ -C ₄ alkyl; hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl). Preferably, Xi, X ₂ , X ₃ and X ₄ are independently selected from O, - NH, -N(CH ₃ ) and -N(C ₆ aryl), wherein the aryl is optionally substituted with at least one halogen, preferably fluoride, or a fluorinated or perfluorinated C ₁ -C ₄ alkyl group. More preferably, at least one of Xi, X ₂ , X ₃ and X ₄ is O, and even more preferably Xi, X ₂ , X ₃ and X ₄ are all O.

In another particular embodiment, R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a (C ₅ -C ₇ )cycloalkyl(Ci- C ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl; and -C(0)0RM, wherein RM is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or in the compounds of formula (la), Ri and R ₃ , or R ₄ and R ₅ when n is 1 , together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl; in the compounds of formula (lb), Ri and R ₃ or R ₃ and R ₅ , and/or R ₄ and R ₇ or R ₄ and Rg, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

In a more particular embodiment, R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0R _M , wherein R _M is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(R ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or in the compounds of formula (la), Ri and R ₃ , or R ₄ and R ₅ when n is i, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl; in the compounds of formula (lb), Ri and R ₃ or R ₃ and R ₅ , and/or R ₄ and R ₇ or R ₄ and Rg, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Even in a more particular embodiment, R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0R _M , wherein R _M is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl.

In a particular embodiment, the process of the invention refers to a process for preparing carbonyl-containing cyclic compounds of formula (la) or (lb).

In a particular embodiment, in the compounds of formula (la), Xi and X ₂ are independently selected from O, -NH, N(C _I -C ₄ alkyl) and -N(C ₆ aryl), wherein the C ₆ aryl is optionally substituted with at least one C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl). Preferably, Xi and X ₂ are independently selected from O, -NH, -N(CH ₃ ) and - N(Ce aryl), wherein the aryl is optionally substituted with at least one halogen, preferably fluoride. More preferably, at least one of Xi and X ₂ is O, and even more preferably Xi and X ₂ are all O. In another particular embodiment, in the compound of formula (la) n is 0.

Within this particular embodiment wherein n is 0, it is preferred that Ri, R ₂ and R ₃ are hydrogen; and R ₄ is hydrogen; a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or a C ₆ -C ₁₀ aryl group, more preferably a phenyl group. It is more preferred that R ₄ is a linear or branched C ₁ -C ₆ alkyl group, even more preferably a C ₁ -C ₃ alkyl, optionally substituted with a hydroxyl.

Within this particular embodiment wherein n is 0, it is also preferred that Ri and R ₃ are hydrogen; and R ₂ and R ₄ together form a C ₅ -C ₇ cycloalkyl group.

It is also preferred that when n is 0, the carbonyl-containing cyclic compound of formula (la) is selected from:

In another particular embodiment, in the compound of formula (la) n is 1.

Within the particular embodiment wherein n is 1, Ri-Re are independently selected from hydrogen; linear or branched CrCe alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a (C ₅ - C ₇ )cycloalkyl(Ci-C ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl; and - C(0)0Ri ₄ , wherein RM is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or Ri and R ₃ , or R ₄ and R ₅ together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Within the particular embodiment wherein n is 1, R ₁ -R ₆ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or Ri and R ₃ , or R ₄ and R ₅ , together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Within the particular embodiment wherein n is 1, R ₁ -R ₆ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl.

Within the particular embodiment wherein n is 1, Ri, R ₂ , Rs and R6 are hydrogen and R ₃ and R ₄ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ - Cio)aryl(Ci-C ₄ )alkyl.

Within the particular embodiment where n is 1 , R ₃ and R ₄ are hydrogen; and Ri, R ₂ , Rs and R6 are independently selected from hydrogen and C ₁ -C ₆ alkyl.

It is preferred that when n is 1 , the carbonyl-containing cyclic compound of formula (la) is selected from: In another particular embodiment, in the compound of formula (lb), Xi, X ₂ , X ₃ and X ₄ are independently selected from O, -NH, -N(CH ₃ ) and -N(C ₆ aryl), wherein the aryl is optionally substituted with at least one halogen, preferably fluoride. More preferably, at least one of Xi , X ₂ , X ₃ and X ₄ is O, and even more preferably Xi , X ₂ , X ₃ and X ₄ are all O.

In another preferred embodiment, in the compound of formula (lb), Y is a single bond. In another preferred embodiment, in the compound of formula (lb), Y is -(CIA _p -O- (CH ₂ )q-, and more preferably index p and/or q is 1.

In a particular embodiment, in the compound of formula (lb) n is 0.

Within this particular embodiment wherein n is 0 in the compounds of formula (lb), Ri- R ₄ and RyRe are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ - C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl.

More preferably, in the compounds of formula (lb), R ₃ and R ₄ are H. It is more preferred that in the compounds of formula (lb) when n is 0, R ₃ and R ₄ are hydrogen; and Ri, R2, R7 and Rs are hydrogen; a linear or branched C1-C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R12 and Ri ₃ are independently selected from H and C1-C4 alkyl; or a C ₆ -C1 ₀ aryl group, more preferably a phenyl group.

Even more preferably, in the compounds of formula (lb) when n is 0, Ri, R ₃ , R4 and R ₇ are hydrogen; and R ₂ and Rs are hydrogen; a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R12 and Ri ₃ are independently selected from H and C1-C4 alkyl; or a C ₆ -C1 ₀ aryl group, more preferably a phenyl group.

It is also preferred that in the compounds of formula (lb) when n is 0, Ri, R ₃ , R4 and R7 are hydrogen; and one of R2 and Rs is hydrogen, and the other a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri2)(Ri ₃ ), wherein R12 and R1 ₃ are independently selected from H and C1-C4 alkyl; or a C ₆ -C ₁₀ aryl group, more preferably a phenyl group.

Even in a more preferred embodiment, in the compounds of formula (lb), R1-R4 and R ₇ -R ₈ are hydrogen.

Within this particular embodiment when n is 0, it is preferred that the carbonyl- containing cyclic compound of formula (lb) is selected from:

In a particular embodiment, in the compound of formula (lb) n is 1.

Within this particular embodiment wherein n is 1 in the compounds of formula (lb), Ri- R1 ₀ are independently selected from hydrogen; linear or branched C1-C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)ORM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ - Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C1-C4 alkyl. It is more preferred that in the compounds of formula (lb) when n is 1, R ₁ -R ₁₀ are hydrogen; a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl; or a C ₆ -C ₁₀ aryl group, more preferably a phenyl group.

Even in a more preferred embodiment, in the compounds of formula (lb) when n is 1, R ₁ -R ₁₀ are hydrogen or a linear or branched C ₁ -C ₆ alkyl group. Most preferably, Ri, R ₂ , R ₅ , R6, R ₇ , Re, R ₉ and R ₁₀ are hydrogen and R ₃ and R ₄ are hydrogen or a linear or branched C ₁ -C ₄ alkyl group. Within this particular embodiment when n is 1, it is preferred that the carbonyl- containing cyclic compound of formula (lb) is selected from:

In another particular embodiment, the process of the invention refers to a process for preparing carbonyl-containing linear compounds of formula (lc).

Within this particular embodiment, it is preferred thatXi is O or N(Rn), wherein Rn is H, a C ₁ -C ₄ alkyl or a C ₆ -C ₁₀ aryl optionally substituted with at least a fluorinated or perfluorinated C ₁ -C ₄ alkyl.

In a preferred embodiment, Xi is O. In another preferred embodiment, Xi is NH.

In another preferred embodiment, Zi is selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a C ₆ -C ₁₀ aryl optionally substituted with at least a Ci- C ₄ alkyl or a fluorinated or perfluorinated C ₁ -C ₄ alkyl; a (C ₅ -C ₇ )cycloalkyl(Ci-C ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ - Cio)aryl(Ci-C ₄ )alkyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl(C ₂ -Ce)alkenyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl; and -C(0)0RM, wherein RM is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C1-C4 alkyl.

In a more particular embodiment, Zi is selected from hydrogen; linear or branched Ci- C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a C ₆ -C ₁₀ aryl optionally substituted with at least a Ci- C ₄ alkyl or a fluorinated or perfluorinated C ₁ -C ₄ alkyl; and -C(0)0RM, wherein RM is a CrCe alkyl, a Ce-Cio aryl or a (Ce-Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the CrCe alkyl and C2-C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C1-C4 alkyl.

Even in a more particular embodiment, Zi is selected from hydrogen; linear or branched CrCe alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a C ₆ -C ₁₀ aryl optionally substituted with at least a C ₁ -C ₄ alkyl or a fluorinated or perfluorinated C ₁ -C ₄ alkyl; and -C(0)0RM, wherein RM is a CrCe alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl.

In a preferred embodiment, Zi is H, C1-C4 alkyl or a C ₆ -C1 ₀ aryl optionally substituted with at least a C1-C4 alkyl or a fluorinated or perfluorinated C1-C4 alkyl, more preferably Zi is C1-C4 alkyl or a C ₆ -C1 ₀ aryl optionally substituted with at least a C1-C4 alkyl or a fluorinated or perfluorinated C1-C4 alkyl.

In another preferred embodiment, Xi is O and Zi is C1-C4 alkyl.

In another preferred embodiment, Xi is NH and Zi is a C ₆ aryl optionally substituted with at least a fluorinated or perfluorinated C1-C4 alkyl.

It is preferred that the carbonyl-containing linear compound of formula (lc) is selected from: The process of the invention uses, as a starting source, BPA-PC of formula (II) as defined above. This polycarbonate may come from a material synthesized for this purpose but, in a preferred and advantageous embodiment, the BPA-PC employed is a waste material so that the reaction can be considered as a recycling reaction.

In fact, in a preferred embodiment, the source of the bisphenol based polycarbonate of formula (II) is a waste material having poly(bisphenol A carbonate).

In a particular embodiment, the bisphenol based polycarbonate of formula (II) can be a mixture or combination of a waste material having poly(bisphenol A carbonate) and a synthetic poly(bisphenol A carbonate).

The use of BPA-PC as a reagent for the synthesis of carbonyl-containing compounds is highly beneficial because of the simplicity and low cost impaired to the process of the invention.

In a preferred embodiment, the BPA-PC of formula (II) has a weight average molecular weight (Mw) of 10000 to 100 000 g-mol ¹ as measured by gel permeation chromatography (GPC) using polystyrene standard.

BPA-PC can be used in the process of the invention in the form of pellets, flakes, powder or in any other solid form.

The process of the invention requires a reagent which provides the different substituents to the carbonyl-containing cyclic compound of formula (I). This reagent is the compound of formula (Ilia), (lllb) or (lllc): H-X ₁ -Z ₁

(lllc) wherein Xi, X ₂ , X ₃ , X ₄ , R ₁ -R ₁₀ , Y, Zi and n are as defined above.

Said compound is selected depending on the compound of formula (la), (lb) or (lc) to be obtained, respectively. The particular and preferred embodiments for Xi, X ₂ , X ₃ , X ₄ , R ₁ -R ₁₀ , Y, Zi and index n in the compounds of formula (Ilia), (I Mb) and (I lie) are the same as those mentioned above for the carbonyl-containing compounds of formula (la), (lb) and (lc).

Thus, in a particular embodiment, Xi, X ₂ , X ₃ and X ₄ are independently selected from O, -NH, N(CI-C ₄ alkyl) and -N(C ₆ aryl), wherein the C ₆ aryl is optionally substituted with at least one C ₁ -C ₄ alkyl, a fluorinated or perfluorinated C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl. Preferably, Xi, X ₂ , X ₃ and X ₄ are independently selected from O, -NH, -N(CH ₃ ) and -N(C ₆ aryl), wherein the aryl is optionally substituted with at least one halogen, preferably fluoride. More preferably, at least one of Xi, X ₂ , X ₃ and X ₄ is O, and even more preferably Xi, X ₂ , X ₃ and X ₄ are all O.

In another particular embodiment, R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a (C ₅ -C ₇ )cycloalkyl(Ci- C ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl; and -C(0)0R _M , wherein R _M is a CrCe alkyl, a Ce-Cio aryl or a (Ce-Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(R ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or in the compounds of formula (Ilia), Ri and R ₃ , or R ₄ and R ₅ when n is 1, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl; in the compounds of formula (lllb), Ri and R ₃ or R ₃ and R ₅ , and/or R ₄ and R ₇ or R ₄ and Rg, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

In a more particular embodiment, R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0R _M , wherein R _M is a CrCe alkyl, a Ce-Cio aryl or a (Ce-Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(R ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or in the compounds of formula (Ilia), Ri and R ₃ , or R ₄ and R ₅ when n is 1, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl; in the compounds of formula (lllb), Ri and R ₃ or R ₃ and R ₅ , and/or R ₄ and R ₇ or R ₄ and Rg, together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Even in a more particular embodiment, R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0R _M , wherein R _M is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl. In a particular embodiment, in the compounds of formula (Ilia), Xi and X ₂ are independently selected from O, -NH, N(C _I -C ₄ alkyl) and -N(C6 aryl), wherein the C6 aryl is optionally substituted with at least one C ₁ -C ₄ alkyl, hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and R ₁₃ are independently selected from H and C ₁ -C ₄ alkyl). Preferably, Xi and X ₂ are independently selected from O, -NH, -N(CH ₃ ) and - N(Ce aryl), wherein the aryl is optionally substituted with at least one halogen, preferably fluoride. More preferably, at least one of Xi and X ₂ is O, and even more preferably Xi and X ₂ are all O.

In another particular embodiment, in the compound of formula (Ilia), n is 0. Within this particular embodiment wherein n is 0, it is preferred that Ri, R ₂ and R ₃ are hydrogen; and R ₄ is hydrogen; a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or a C ₆ -C ₁₀ aryl group, more preferably a phenyl group. It is more preferred that R ₄ is a linear or branched C ₁ -C ₆ alkyl group, even more preferably a C ₁ -C ₃ alkyl, optionally substituted with a hydroxyl.

Within this particular embodiment wherein n is 0, it is also preferred that Ri and R ₃ are hydrogen; and R ₂ and R ₄ together form a C ₅ -C ₇ cycloalkyl group.

It is also preferred that when n is 0, the compound of formula (Ilia) is selected from:

In another particular embodiment, in the compound of formula (Ilia), n is 1.

Within the particular embodiment wherein n is 1, R ₁ -R ₆ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; a (C ₅ - C ₇ )cycloalkyl(Ci-C ₄ )alkyl, wherein the cycloalkyl is optionally substituted with at least one C ₁ -C ₄ alkyl; a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₆ -Cio)aryl(C ₂ -C ₆ )alkenyl, wherein the aryl is optionally substituted with at least one C ₁ -C ₄ alkyl; a “(C ₅ -Cio)heteroaryl(Ci-C ₄ )alkyl”, wherein the heteroaryl is optionally substituted with at least one C ₁ -C ₄ alkyl; and - C(0)0Ri ₄ , wherein RM is a CrCe alkyl, a Ce-Cio aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or Ri and R ₃ , or R ₄ and R ₅ together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Within the particular embodiment wherein n is 1, R ₁ -R ₆ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C ₁ -C ₄ alkyl; or Ri and R ₃ , or R ₄ and R ₅ , together can form a C ₅ -C ₇ cycloalkyl or C ₅ -C ₆ heterocyclyl group optionally substituted with C ₁ -C ₄ alkyl.

Within the particular embodiment wherein n is 1, R ₁ -R ₆ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl.

Within the particular embodiment wherein n is 1, Ri, R ₂ , Rs and R6 are hydrogen and R ₃ and R ₄ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0RM, wherein RM is a C ₁ -C ₆ alkyl, a C ₆ -C ₁₀ aryl or a (C ₆ - Cio)aryl(Ci-C ₄ )alkyl.

Within the particular embodiment where n is 1, R ₃ and R ₄ are hydrogen; and Ri, R ₂ , Rs and R6 are independently selected from hydrogen and C ₁ -C ₆ alkyl.

In a preferred embodiment, when n is 1, the compound of formula (Ilia) is selected from:

In another particular embodiment, in the compound of formula (I I lb), Xi, X ₂ , X ₃ and X ₄ are independently selected from O, -NH, -N(CH ₃ ) and -N(C ₆ aryl), wherein the aryl is optionally substituted with at least one halogen, preferably fluoride. More preferably, at least one of Xi , X ₂ , X ₃ and X ₄ is O, and even more preferably Xi , X ₂ , X ₃ and X ₄ are all O. In another preferred embodiment, in the compound of formula (Nib), Y is a single bond.

In another preferred embodiment, in the compound of formula (Nib), Y is -(Chh O- (CH ₂ )q-, and more preferably index p and/or q is 1.

In a particular embodiment, in the compound of formula (Nib) n is 0. Within this particular embodiment wherein n is 0 in the compounds of formula (Nib), R ₁ -R ₄ and RyRe are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0R _M , wherein R _M is a C ₁ -C ₆ alkyl, a C ₆ - C ₁₀ aryl or a (C ₆ -Cio)aryl(Ci-C ₄ )alkyl; and wherein any of the C ₁ -C ₆ alkyl and C ₂ -C ₆ alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ) wherein R ₁₂ and Ri ₃ are independently selected from H and C1-C4 alkyl.

More preferably, in the compounds of formula (lllb) when n is 0, R ₃ and R ₄ are H.

It is more preferred that in the compounds of formula (lllb) when n is 0, R ₃ and R ₄ are hydrogen; and Ri, R2, R7 and Rs are hydrogen; a linear or branched C1-C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R12 and Ri ₃ are independently selected from H and C1-C4 alkyl; or a C ₆ -C1 ₀ aryl group, more preferably a phenyl group.

Even more preferably, in the compounds of formula (lllb), Ri, R ₃ , R4 and R7 are hydrogen; and R ₂ and Rs are hydrogen; a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri ₂ )(Ri ₃ ), wherein R12 and Ri ₃ are independently selected from H and C1-C4 alkyl; or a C ₆ -C1 ₀ aryl group, more preferably a phenyl group.

It is also preferred that in the compounds of formula (lllb) when n is 0, Ri, R ₃ , R4 and R7 are hydrogen; and one of R2 and Rs is hydrogen, and the other a linear or branched C ₁ -C ₆ alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri2)(Ri ₃ ), wherein R12 and R1 ₃ are independently selected from H and C1-C4 alkyl; or a C ₆ -C ₁₀ aryl group, more preferably a phenyl group.

Even in a more preferred embodiment, in the compounds of formula (lllb) when n is 0, R1-R4 and R7-R ₈ are hydrogen.

Within this particular embodiment when n is 0, it is preferred that the compound of formula (lllb) is selected from:

In a particular embodiment, in the compound of formula (lllb) n is 1. Within this particular embodiment wherein n is 1 in the compounds of formula (lllb), R ₁ -R ₁₀ are independently selected from hydrogen; linear or branched C ₁ -C ₆ alkyl optionally containing at least one heteroatom intercalated in the alkyl chain; linear or branched C ₂ -C ₆ alkenyl optionally containing at least one heteroatom intercalated in the alkenyl chain; and -C(0)0R _M , wherein R _M is a C1-C6 alkyl, a C6-C10 aryl or a (C ₆ - Cio)aryl(Ci-C4)alkyl; and wherein any of the C1-C6 alkyl and C2-C6 alkenyl group can be optionally substituted with an hydroxyl, halogen or amine group N(Ri2)(Ri3) wherein R12 and Ri3 are independently selected from H and C1-C4 alkyl.

It is more preferred that in the compounds of formula (Nib) when n is 1, R1-R1 ₀ are hydrogen; a linear or branched C1-C6 alkyl group optionally substituted with an hydroxyl, halogen or amine group N(Ri2)(Ri3), wherein R12 and R13 are independently selected from H and C1-C4 alkyl; or a C ₆ -C1 ₀ aryl group, more preferably a phenyl group.

Even in a more preferred embodiment, in the compounds of formula (Nib) when n is 1 , R1-R1 ₀ are hydrogen or a linear or branched C1-C ₆ alkyl group. Most preferably, Ri , R2, R5, R6, R7, Re, R ₉ and R1 ₀ are hydrogen and R ₃ and R4 are hydrogen or a linear or branched C1-C4 alkyl group. Within this particular embodiment when n is 1, it is preferred that the carbonyl- containing cyclic compound of formula (Nib) is selected from:

In another particular embodiment, in the compound of formula (I lie), X1 is selected from O, NH, N(CH3) and N(C6 aryl), wherein the aryl is optionally substituted with at least a C1-C4 alkyl or a fluorinated or perfluorinated C1-C4 alkyl. More preferably X1 is O or NH.

In another particular embodiment, Z1 is H, C1-C4 alkyl or a C ₆ -C1 ₀ aryl optionally substituted with at least a C1-C4 alkyl or a fluorinated or perfluorinated C1-C4 alkyl, more preferably Zi is C1-C4 alkyl or a C ₆ -C1 ₀ aryl optionally substituted with at least a C1-C4 alkyl or a fluorinated or perfluorinated C1-C4 alkyl.

In another preferred embodiment, Xi is O and Zi is C1-C4 alkyl. In another preferred embodiment, Xi is NH and Zi is a C ₆ aryl optionally substituted with at least a fluorinated or perfluorinated C1-C4 alkyl.

It is preferred that the carbonyl-containing linear compound of formula (I lie) is selected from: By means of a transesterification reaction between BPA-PC of formula (II) and the compound of formula (Ilia), which acts as a nucleophile, Bisphenol A (BPA) is obtained along with the corresponding cyclic carbonyl-containing compound of formula (la), according to the following reaction:

In the same way, a transesterification reaction between BPA-PC of formula (II) and the compound of formula (Nib) leads to Bisphenol A (BPA) along with the corresponding cyclic carbonyl-containing compound of formula (lb), according to the following reaction: Similarly, a transesterification reaction between BPA-PC of formula (II) and the compound of formula (I lie) leads to Bisphenol A (BPA) along with the corresponding linear carbonyl-containing compound of formula (lc), according to the following reaction:

Accordingly, the process of the invention allows the production of a large variety of carbonyl-containing compounds, both cyclic and linear, either unsubstituted or substituted with different functionalities, which can be used as monomers for the synthesis of the corresponding polymers by polymerization reactions. In the particular case when carbonyl-containing cyclic compounds are obtained, the corresponding polymers can be prepared by ring-opening polymerization reactions. Depending on the substituents present in the carbonyl-containing cyclic compound, polymers with different properties can be obtained, such as biocompatibility, biodegradability, conductivity, antimicrobial and antifungal properties, resistance to heat, etc.

On the other hand, the process of the invention provides not only a carbonyl- containing compound of formula (la), (lb) or (lc), but also BPA, which can also be used as monomer to produce further BPA-PC. The process of the invention is carried out in the presence of a catalyst, namely an imidazole or a derivative thereof.

The imidazole or derivative thereof can be represented by formula (IV): or any tautomeric form thereof; wherein:

Z and W are independently selected from C and N, provided that Z and W are not simultaneously N; Ri ₅ , Ri ₆ , Ri7 and Ris are independently selected from H and a C1-C4 alkyl group or Ri7 and Ris can form a C6 aryl group when Z is C.

In a preferred embodiment, R15-R18 are independently selected from hydrogen and C1-C4 alkyl, more preferably from hydrogen and methyl. In a more preferred embodiment, R15-R18 are hydrogen.

In another preferred embodiment, Z is C.

In another preferred embodiment, Z is N.

In another preferred embodiment, the catalyst has formula (IVa): wherein:

Ris, R1 ₆ , Ri7 and Ris are independently selected from H and a C1-C4 alkyl group or Ri7 and Ris can form a C6 aryl group;

Z is C or N, provided that when Z is N then R17 does not exist; In another preferred embodiment, R16 is H. In another preferred embodiment, R15-R18 are hydrogen.

In a more preferred embodiment, the catalyst is selected from imidazole, 1,2,3- triazole, 1,2,4-triazole, benzimidazole and 1 H-benzotriazole: Even more preferably, the catalyst is imidazole.

The process of the invention is also performed in the presence of an organic solvent. A skilled person could easily recognise the suitable organic solvent to be used in the process of the invention depending on the reactants and the catalyst used.

In a preferred embodiment, the organic solvent is selected from methyl imidazole, tetrahydrofuran, chloroform and 2-methyl-tetrahydrofuran. Even more preferable is the use of methyl imidazole as organic solvent.

In a particular embodiment, the compound of formula (Ilia), (I Mb) or (lllc), the catalyst of formula (IV) or (Iva) and BPA-PC of formula (II) are mixed in the organic solvent in any order.

In a preferred embodiment, the BPA-PC and the catalyst are added in equimolar amounts, whereas the compound of formula (III) is added slightly in excess. For example, between 1.02 and 1.2 equivalents of compound of formula (III) are added per equivalent of BPA-PC and catalyst.

A significant advantage of the process of the invention is the use of imidazole or a derivative thereof of formula (IV) or (IVa) as catalyst in combination with an organic solvent since they allow the carbonyl-containing compound of formula (la), (lb) or (lc) to be obtained at low temperatures without requiring a protective atmosphere.

Thus, in a particular embodiment, the process of the invention is carried out at a temperature below 80°C, more preferably from 25 to 60°C, even more preferably from 25 to 55°C, and most preferably from 30 to 50°C.

In another particular embodiment, the process of the invention is carried out in less than 5 hours, even more preferably in less than 2 hours.

In another particular embodiment, the process of the invention is performed under a non-protective atmosphere, i.e., an atmosphere containing oxygen.

Furthermore, the process is preferably conducted under atmospheric pressure.

The compounds of formula (la), (lb) or (lc) resulting from the process of the invention can be further purified once obtained using conventional techniques, such as column chromatography and liquid-liquid extraction.

Examples Abreviations:

BPA: Bisphenol A

BPA-PC: Bisphenol A polycarbonate TMC: trimethylene carbonate DMSO: dimethylsulfoxide

Example 1. Synthesis of H ,31dioxan-2-one (TMC) using imidazole as catalyst and 1- methyl imidazole as solvent

BPA-PC pellets (1 g, 3.94 mmol, 1 eq.), 1,3-propanediol (0.31 g, 4.14 mmol, 1.05 eq.), imidazole (0.27 g, 3.94 mmol, 1 eq.) and 1-methyl imidazole (3.23 g, 39.4 mmol, 10 eq.) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 50 °C. After 2 h, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product.

After a flash column in acetone/hexane 80/20, 0.31 g (78 % yield) of 1,3-dioxan-2-one (TMC) were recovered as white powder, while 0.83 g (92 % yield) of Bisphenol A were recovered as white powder. ¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of TMC: 4.38 (t, 4H), 2.02 (qq, 2H)

¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).

Example 2. Synthesis of 5-((allyloxy)methyl)-5-ethyl-1,3-dioxan-2-one usinq imidazole as catalyst and 1-Methylimidazole as solvent BPA-PC pellets (1 g, 3.94 mmol, 1 eq.), 2-((allyloxy)methyl)-2-ethylpropane-1,3-diol (0.72 g, 4.14 mmol, 1.05 eq.), imidazole (0.27 g, 3.94 mmol, 1 eq.) and 1-methyl imidazole (3.23 g, 39.4 mmol, 10 eq.) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 50 °C.

After 1 h, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product. After a flash column in acetone/hexane 70/30, 0.71 g (91 % yield) of 5-((allyloxy)methyl)- 5-ethyl-1 ,3-dioxan-2-one were recovered as white powder, while 0.85 g (94 % yield) of Bisphenol A were recovered as white powder.

¹ H NMR (400 MHz, DMSO-d6) d (ppm) of 5-((allyloxy)methyl)-5-ethyl-1 ,3-dioxan-2-one: 5.94 - 5.82 (m, 1 H), 5.30 - 5.16 (m, 2H), 4.25 (q, 4H), 3.97 (d, 2H), 3.38 (s, 2H), 1.40 (q, 2H), 0.85 (t, 3H)

¹ H NMR (400 MHz, DMSO-d6) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).

Example 3. Synthesis of 5,5-dimethyltetra hydropyrimidin-2-one using imidazole as catalyst and 2-methyltetrahydrofuran as solvent BPA-PC pellets (1 g, 3.94 mmol, 1 eq.), 2, 2-dimethylpropane-1, 3-diamine (0.42 g, 4.14 mmol, 1.05 eq.), imidazole (0.54 g, 7.88 mmol, 2 eq.) and 2-methyltetrahydrofuran (4 ml_ 3,39 g, 39.4 mmol, 10 eq.) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at room temperature.

After 30 min, the crude product was filtered to remove the eventual polymeric side- product and 2-methyltetrahydrofuran was removed through rotary evaporation.

The resulting product was precipitated in diethyl ether and filtrated on Buchner prior to be collected and dried, 0.41 g (82 % yield) of 5,5-dimethyltetra hydropyrimidin-2-one were recovered as white powder, after evaporation of diethyl ether and precipitation in chloroform, 0.82 g (91 % yield) of Bisphenol A were recovered as white powder.

¹ H NMR (400 MHz, 298 K, DMSO-de) d (ppm) of 5,5-dimethyltetra hydropyrimidin-2-one: 6.05 (s, 2H), 2.77 (s, 4H), 0.95 (s, 6H)

¹ H NMR (400 MHz, DMSO-de) d (ppm) of BPA: 9.13 (s, 2H), 6.98 (d, 4H), 6.67 (d, 4H), 1.52 (s, 3H).

Example 4. Synthesis of H ,31dioxan-2-one (TMC) using triazole as catalyst and 1- methylimidazole as solvent

BPA-PC pellets (1 g, 3.94 mmol, 1 eq.), 1,3-propanediol (0.31 g, 4.14 mmol, 1.05 eq.), 1,2,4-1H-triazole (0.272 g, 3.94 mmol, 1 eq.) and 1-methyl imidazole (3.23 g, 39.4 mmol, 10 eq.) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 50 °C.

After 3 h, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product. After a flash column in acetone/hexane 80/20, 0.28 g (70 % yield) of 1,3-dioxan-2-one (TMC) were recovered as white powder, while 0.75 g (83 % yield) of Bisphenol A were recovered as white powder.

¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of TMC: 4.38 (t, 4H), 2.02 (qq, 2H) ¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).

Example 5. Synthesis of H ,31dioxan-2-one (TMC) using imidazole as catalyst and chloroform as solvent

BPA-PC pellets (1 g, 3.94 mmol, 1 eq.), 1 ,3-propanediol (0.31 g, 4.14 mmol, 1.05 eq.), imidazole (0.54 g, 7.88 mmol, 2 eq.), and chloroform (4 ml_ 5.96 g, 49.5 mmol, 12.56 eq.) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 50 °C.

After 1 h, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product.

After a flash column in acetone/hexane 80/20, 0.19 g (49 % yield) of 1,3-dioxan-2-one (TMC) were recovered as white powder, while 0.59 g (65 % yield) of Bisphenol A were recovered as white powder.

¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of TMC: 4.38 (t, 4H), 2.02 (qq, 2H)

¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H). Example 6. Synthesis of 5,5'-(oxybis(methylene))bis(5-ethyl-1,3-dioxan-2-one) usinq imidazole as catalyst and 1-methylimidazole as solvent 5,5'-(oxybis(methylene)) bis(5-ethyl-1 ,3-dioxan-2-one)

BPA-PC pellets (1 g, 3.94 mmol, 1 eq.), 2,2'-Oxybis(methylene)bis(2-ethyl-1,3- propanediol) (0.51 g, 2,06 mmol, 1.05 eq.), imidazole (0.266 g, 3.921 mmol, 1 eq.) and 1-Methylimidazole (3.219 g, 39.21 mmol, 10 eq.) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 50 °C.

After 3 h, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product.

After a flash column in acetone/hexane 80/20, 0.454 g (73 % yield) of 5,5'- (oxybis(methylene))bis(5-ethyl-1,3-dioxan-2-one) were recovered as white powder, while 0.644 g (71 % yield) of Bisphenol A were recovered as white powder.

¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of 5,5'-(oxybis(methylene))bis(5-ethyl-1,3- dioxan-2-one): 4.29 (d, 4H), 4.23 (d, 4H), 3.41 (s, 4H), 1.39 (q, 4H), 0.84 (t, 6H).

¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).

Example 7. Synthesis of dimethyl carbonate using imidazole as catalyst and chloroform as solvent BPA-PC pellets (20 g, 78.4 mmol, 1 eq.), methanol (7.5 g, 235 mmol, 3 eq.), imidazole (5.3 g, 78.4 mmol, 1 eq.), triethylamine (1,58 g 15,68 mmol) and chloroform (40 ml_) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 60°C. After 30 min, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product. The crude was kept in a freezer at 0 °C degrees overnight to precipitate the bisphenol A. The so formed bisphenol A crystals were filtrated, washed with 30 ml Chloroform and dried prior to be collected (13.41 g, 75% yield. The solution was distillated to obtain 4.94 g of dimethyl carbonate (70% yield) and recover the chloroform, triethylamine and imidazole used in the process.

¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of dimethyl carbonate: 3.7 (s, 6H)

¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H). Example 8. Synthesis of diethyl carbonate using imidazole as catalyst and chloroform as solvent

BPA-PC pellets (20 g, 78.4 mmol, 1 eq.), ethanol (10.8 g, 235 mmol, 3 eq.), imidazole (5.3 g, 78.4 mmol, 1 eq.), triethylamine (1 ,58 g 15,68 mmol) and chloroform (40 ml_) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 60°C.

After 1 h, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product. The crude was kept in a freezer at 0 °C degrees overnight to precipitate the bisphenol A. The so formed bisphenol A crystals were filtrated, washed with 30 ml Chloroform and dried prior to be collected (13.41 g, 75% yield. The solution was distillated in order to obtain 6.67 g of diethyl carbonate (72% yield) and recover the chloroform, triethylamine and imidazole used in the process.

¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of diethyl carbonate: 4.11 (q, 4H) 1.21 (q, 6H). ¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).

Example 9. Synthesis of 1, 3-diphenyl urea using imidazole as catalyst and 1 -methyl imidazole as solvent

BPA-PC pellets (10 g, 39.2 mmol, 1 eq.), aniline (3.8 g, 41.2 mmol, 1.05 eq.), imidazole (2,6 g, 39.2 mmol, 1 eq.), and 1-Methylimidazole (15 ml_) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 40°C.

After 30 min, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product. Then methanol, 40 ml were added to the solution and it was introduced in a freezer at 0°C degrees to precipitate the 1 ,3-diphenylurea. The so formed 1,3-diphenylurea crystals were filtrated, and dried prior to be collected (6.90 g, 83% yield.

¹ H NMR (400 MHz, 298 K, DMSO-d ₆ ) d (ppm) of diphenyl urea: 8.66 (s, 2H), 7.46 (d, 2H), 7.28 (t, 4H), 6.97(t, 2H).

¹ H NMR (400 MHz, DMSO-d ₆ ) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).

Example 10. Synthesis of 1,3-bis(3,5-bis(trifluoromethyl)phenyl)urea using imidazole as catalyst and 1 -methyl imidazole as solvent

BPA-PC pellets (10 g, 39.2 mmol, 1 eq.), 3,5-bis(trifluoromethyl)aniline (9.4 g, 41.2 mmol, 1.05 eq.), imidazole (2,6 g, 39.2 mmol, 1 eq.), and 1-Methylimidazole (15 ml_) were charged in a vial which was immersed in an oil bath. Reaction was carried out under stirring and under atmospheric pressure at 40°.

After 15 min, the crude product was cooled to room temperature and filtered to remove the eventual polymeric side-product. Then 40 ml of ethyl acetate were added to the crude to precipitate the product. After the addition the solution was kept in a freezer at 0 °C for 7 hours. The so formed crystals were filtrated, dried and collected (11.5 g 61% yield).

¹ H NMR (400 MHz, 298 K, DMSO-de) d (ppm) of 1,3-bis(3,5-bis(trifluoromethyl) phenyl)urea: 9.53 (s, 2H), 7.97 (s, 4H), 7.48 (s, 2H).

¹ H NMR (400 MHz, DMSO-de) d (ppm) of BPA: 9.12 (s, 2H), 6.96 (d, 4H), 6.65 (d, 4H), 1.53 (s, 3H).