Additive / catalyst free aminolysis for depolymerization of real-life polycarbonates to value added products

Abstract

The present disclosure relates to a novel process for the depolymerization of waste polycarbonates (PC), into valuable carbamates and diols through a greener approach. Specifically, present invention relates to an efficient and environmentally friendly process to depolymerize polycarbonates into monoaminocarbamate, bisaminocarbamate, and their diol without employing catalysts or additives and operates at ambient temperature under air, utilizing green solvents.

Description

[0001] ADDITIVE / CATALYST FREE AMINOLYSIS FOR DEPOLYMERIZATION OF REAL-LIFE POLYCARBONATES TO VALUE ADDED PRODUCTS

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates to a novel process for the depolymerization of waste polycarbonates (PC), into valuable carbamates and diols through a greener approach. Specifically, present invention relates to an efficient and environmentally friendly process to depolymerize polycarbonates into monoaminocarbamate, bisaminocarbamate, and their diol without employing catalysts or additives and operates at ambient temperature under air, utilizing green solvents.

[0004] BACKGROUND OF THE INVENTION

[0005] Polycarbonate (PC) production have seen a significant surge in the global polycarbonate markets by surpassing 4.72 metric million tons in 2022 with an anticipated annual growth rate of 4.38 % until next 10 years. Its superior properties make it a suitable material for various industries such as automobiles, construction, optical, safety goods and many more. However, the fate of after use plastic is still undefined and majority of plastics which is produced ending up as landfills. The heaps of unsegregated waste causing air, land, and water pollution which has drawn an attention of scientific communities to find the efficient way to re / upcycle the waste. Miniature amount of polycarbonate is recycled via mechanical recycling, but majority of its going to the landfills or for incineration. On contrary, chemical recycling could be appropriate method for the treatment of end-of-life or postconsumer plastic waste by using catalyst or reagent selective functionalization’s which can bring back its virgin monomers or other value-added products. However only handful approaches are existed so far for the polycarbonates recycling / upcycling.

[0006] The recycling of polycarbonates is a pressing issue that warrants greater attention. This involves decomposition of polycarbonates to its monomer, its separation, and the upcycling of monomer to other valuable products. Unfortunately, insolubility of polycarbonates makes this process very challenging and mandate the requirements of harsh reaction conditions such as high temperature, pressure etc. Various approaches such as pyrolysis, hydrolysis, alcoholysis and aminolysis have been utilized for the degradation of polycarbonates. Among all aminolysis can be considered as the efficient process compared to other processes as mentioned above which are energy intensive, costly and harmful to the environment. There are reports where PC are depolymerized by reacting with primary n- amine with different catalysts such as NaOH, ZnCh, AICI3, etc. or reacting n- Hexamethylenediamine (HDA) and Diamino siloxanes with additive diisocyanates. However, such use of catalysts and additives are not preferable as it increases side products and impurities thus have lesser yield and conversion to desired products.

[0007] Oku and co-workers (S. Hata, H. Goto, E. Yamada, A. Oku, Polymer. 2002, 43, 2109- 2116) demonstrated that in aminolysis, nucleophilic attack of amine to the carbonate led to the corresponding products. Specifically, solvolytic aminolysis, using AAli methyl- 1 ,2- diaminomethane (DMDAE) produced BP A and dimethyl carbonate at 100 °C for 12 h.

[0008] Shenghong A. Dai and coworkers (C. H. Wu, L. Y. Chen, R. J. Jeng, S. A. Dai, ACS Sustainable Chem. Eng. 2018, 6, 8964-8975) showed even the recycling of BPA which was obtained as product was utilized as raw material for the synthesis of polyurethanes.

[0009] Therefore, there is a long-standing need in the art of an improved process for developing a sustainable approach for depolymerizing the real-life polycarbonate (PC) to get valuable carbamate species along with virgin monomer under ambient conditions with successful redemption in use of stoichiometric amount of reagents at room temperature.

[0010] Considering the above mentioned drawbacks, the current inventors have developed an eco- friendly method to depolymerize PC, wherein monomers were obtained along with monoaminocarbamate and bisaminocarbamate species. The developed method is metal free, works at room temperature under ambient conditions with greener solvent and avoids high temperature, super stoichiometric amount of additives or reagents. This method not only enhances energy efficiency but also facilitates the recovery of raw materials with 100% atom economy, aligning with the principles of life cycle assessment.

[0011] OBJECTS OF THE INVENTION

[0012] An object of the present disclosure is to provide a process of conversion of polycarbonate (PC) based wastes into value added products by depolymerization.

[0013] Another object of the present disclosure is to provide a process for depolymerizing the polycarbonate waste to bisphenol A, monoaminocarbamate and bisaminocarbamate. Still another objective of the invention is to provide a process of conversion of polycarbonate (PC) based wastes that is catalyst free, additive free.

[0014] Still another objective of the invention is to provide a process of conversion of polycarbonate (PC) based wastes into value added products by depolymerisation by treating polycarbonate waste with secondary amine (R2NH; R2 = alkyl, aryl, heteroaryl), under mild conditions covering a solvent, room temperature and in an open air for time period in the range of 30 to 90 minutes to obtain value added products.

[0015] SUMMARY OF THE INVENTION

[0016] In an aspect, the present disclosure provides a process of preparation of value added products by depolymerization of polycarbonate, comprising reacting the polycarbonate with secondary amine as aminolytic agent in presence of a solvent at temperature in the range of 25-30 °C for time period in the range of 30-90 minutes to obtain the value added products, wherein the process is a catalyst free process, and additive free process.

[0017] In an embodiment, the value added products are selected from bisphenol A [4,4'-(propane- 2,2-diyl)diphenol], monoaminocarbamate and bisaminocarbamate or combination thereof.

[0018] In an embodiment, the value added products are selected from: i. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl morpholine-4-carboxylate (4a), ii. propane-2, 2-diylbis(4,l -phenylene) bis(morpholine-4-carboxylate) (5a), iii. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl piperidine- 1 -carboxylate (4b), iv. propane-2, 2-diylbis(4,l -phenylene) bis(piperidine-l-carboxylate)(5b), v. 4-(2-(4-hydroxyphenyl) propan-2-yl) phenyl pyrrolidine- l-carboxylate(4c), vi. propane-2, 2-diylbis(4, 1 -phenylene) bis(pyrrolidine- l-carboxylate(5c), vii. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenylazetidine- 1 -carboxylate (4d), viii. propane-2, 2-diylbis(4,l -phenylene) bis(azetidine- 1 -carboxylate) (5d), ix. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl-4-methoxypiperidine-l -carboxylate (4e), x. 4-(2-(4-((4-methoxycyclohexane- l-carbonyl)oxy)phenyl)propan-2-yl)phenyl 4- methoxypiperidine- 1 -carboxylate (5e), xi. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl 4-phenylpiperidine-l -carboxylate (4f), xii. propane-2, 2-diylbis(4, l-phenylene)bis(4-phenylpiperidine- l-carboxylate)(5f), xiii. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(9-chlorodibenzo[d,f][l,3]oxazepin- 6-yl)piperazine- 1 -carboxylate (4i) , xiv. propane-2, 2-diylbis(4,l-phenylene)bis(4-(9-chlorodibenzo[d,f][l,3]oxazepin-6- yl)piperazine- 1 -carboxylate) (5i), xv. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(7-chloro-5,10-dihydro-l lH benzo[4,5]cyclohepta[l,2-b]pyridin-l l-ylidene)piperidine-l -carboxylate (4j), and xvi. Propane-2,2-diylbis(4,l-phenylene)bis(4- (8chloro5,6dihydrol lHbenzo[5,6]cyclohepta[l,2-b]pyridin-l l-ylidene)piperidine- 1 -carboxylate) (5j ) .

[0019] In an embodiment, the value added products based on monoaminocarbamate is selected from:

[0020] 1) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl morpholine-4-carboxylate (4a),

[0021] 2) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl piperidine- 1 -carboxylate (4b),

[0022] 3) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl pyrrolidine- 1 -carboxylate (4c),

[0023] 4) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl azetidine- 1 -carboxylate (4d),

[0024] 5) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl-4-methoxypiperidine-l -carboxylate (4e),

[0025] 6) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl 4-phenylpiperidine-l -carboxylate (4f),

[0026] 7) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(9-chlorodibenzo[d,f][l,3]oxazepin- 6-yl)piperazine-l -carboxylate (4i), and

[0027] 8) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(7-chloro-5,10-dihydro-l lH benzo[4,5]cyclohepta[l,2-b]pyridin-l l-ylidene)piperidine-l-carboxylate (4j).

[0028] In an embodiment, the value added products based on bisaminocarbamate is selected from: i. propane-2, 2-diylbis(4,l -phenylene) bis(morpholine-4-carboxylate) (5a), ii. propane-2, 2-diylbis(4,l -phenylene) bis(piperidine-l-carboxylate)(5b), iii. propane-2, 2-diylbis(4, 1 -phenylene) bis(pyrrolidine- l-carboxylate(5c), iv. propane-2, 2-diylbis(4,l -phenylene) bis(azetidine- 1 -carboxylate) (5d), v. 4-(2-(4-((4-methoxycyclohexane-l-carbonyl)oxy)phenyl)propan-2-yl)phenyl-4- methoxypiperidine- 1 -carboxylate (5e), vi. propane-2, 2-diylbis(4,l -phenylene) bis(4-phenylpiperidine-l -carboxylate) (5f), vii. propane-2, 2-diylbis(4,l-phenylene)bis(4-(9-chlorodibenzo[d,f][l,3]oxazepin-6- yl)piperazine- 1 -carboxylate) (5i), and viii. propane-2,2-diylbis(4,l-phenylene)bis(4-(8-chloro-5,6-dihydro-l l-H- benzo[5,6]cyclohepta[l,2-b]pyridin-l l-ylidene)piperidine-l-carboxylate)(5j).

[0029] In an embodiment, the secondary amine is selected from cyclic secondary amine, and derivatives thereof.

[0030] In preferred embodiment, the reaction time of the process is in the range of 30-60 minutes.

[0031] In preferred embodiment, the process is done without the need for pretreatment.

[0032] In an embodiment, the secondary amine is selected from piperidine, pyrrolidine, azetidine, 4-methoxypiperidine, 4-phenylpiperidine, 2, 5-dihydro-lH-pyrrole, and thiomorpholine or any combination thereof.

[0033] In an embodiment, the solvent is selected from dichloromethane (DCM), acetone, tetrahydrofuran (THF), and 1, 4-dioxane or any of mixture thereof.

[0034] In an embodiment, the process optionally comprises a base.

[0035] In an embodiment, the base is selected from cesium carbonate (CS2CO3), 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU), tripotassium phosphate (K3PO4), and potassium tert-butoxide (KOtBu), or any combination thereof.

[0036] In an embodiment, the polycarbonate is a waste polycarbonate based on a material selected from waste CD disc, helmet, laboratory safety goggle, and roof sheet.

[0037] In an embodiment, the yield of the bisphenol A is in range of 22-32%, yield of the monoaminocarbamate is in range of 65-72%, and yield of the bisaminocarbamate is in range of 40 to 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.

[0039] The features and advantages of the present disclosure will become more apparent from the following detailed description along with the accompanying figures, which forms a part of this application and in which:

[0040] FIG. 1 illustrates the GPC data for real life polycarbonates.

[0041] FIG. 2 illustrates the ORTEP diagram of compound 3a. The asymmetric unit contains three molecules. Herein, the ellipsoids are drawn with a 50% probability.

[0042] FIG. 3 illustrates the ORTEP diagram of compound 4a. The asymmetric unit contains a single molecule. Herein, the ellipsoids are drawn with a 50% probability.

[0043] FIG. 4 illustrates the ORTEP diagram of compound 5a. The asymmetric unit contains a single molecule. Herein, the ellipsoids are drawn with a 50% probability.

[0044] FIG. 5 illustrates the catalyst free aminolysis for depolymerization of the polycarbonate to carbamates and BPA.

[0045] FIG. 6 illustrates the synthesis of carbamates and BPA using morpholine as aminolytic reagent.

[0046] FIG. 7 illustrates the depolymerization of the polycarbonate to carbamates and monomer BPA.

[0047] FIG. 8 illustrates the derivatization of bisaminocarbamate (5c).

[0048] DETAILED DESCRIPTION OF THE INVENTION

[0049] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

[0050] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0051] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0052] In some embodiments, numbers have been used for quantifying weights, percentages, ratios, and so forth, to describe and claim certain embodiments of the invention and are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0053] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[0054] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”

[0055] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.

[0056] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0057] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.

[0058] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present disclosure. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.

[0059] It should also be appreciated that the present disclosure can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.

[0060] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

[0061] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus, if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

[0062] The term "or", as used herein, is generally employed in its sense including "and / or" unless the content clearly dictates otherwise.

[0063] The polycarbonate (PC) or poly(bisphenol A carbonate) (PC-BPA) is a high-performance engineering thermoplastic based on bisphenol A, and its recycling poses different challenges due to its aromatic backbone and thermal stability.

[0064] The present invention provides a process of conversion of polycarbonate (PC) based wastes into value added products by depolymerization, wherein the process is carried out by treating polycarbonate waste with secondary amine under mild conditions covering a solvent, at a temperature in the range of 25 to 30 °C, and in an open air for time period in the range of 30 to 90 minutes to obtain value added products; wherein the process is catalyst free, additive free.

[0065] In some embodiments, the value added products are bisphenol A, monoaminocarbamate and bisaminocarbamate.

[0066] In some embodiments, the secondary amine is cyclic secondary amines and its derivatives.

[0067] In some embodiments, the obtained BPA: 1st carbamate: 2nd carbamate is in range of 1:2: 1. In some embodiments, the yield of BPA is in range of 22-32%, 1st carbamate is in range of 65-72%, and 2nd carbamate is in range of 40 to 50%.

[0068] In some embodiments, the amine is selected from piperidine, pyrrolidine, azetidine, 4- methoxypiperidine, 4-phenylpiperidine, 2,5-dihydro-lH-pyrrole, thiomorpholine or combinations thereof.

[0069] In some embodiments, the solvent is selected from DCM, acetone, THF, 1,4 dioxane or mixture thereof.

[0070] In some embodiments, the solvent is acetone.

[0071] The optimization experiments were performed on the waste CD disc (Mn = 12,016 g / mol, Mw = 21,724 g / mol) and morpholine as standard substrates. The upcycling of PC using amines as nucleophile was aimed to get carbamates derivatives. Primary amines like aniline, and cyclohexyl amine were found ineffective to deliver the carbamates under the reaction conditions but were effective to deliver the urea derivatives. Similarly tertiary amine was found ineffective for aminolysis of PC and starting material was retained after the reaction.

[0072] The depolymerization of polycarbonate to its monomer BPA, mono aminocarbamate and bisaminocarbamate was observed upon introducing secondary amines. This indicates that the strength of the nucleophile dictates the fate of depolymerization of the polycarbonate.

[0073] For the initial screening, secondary amines were utilized as aminolytic agents in presence of catalytic amount of base using DCM as solvent for one hour at room temperature under air to get the carbamate. This resulted in monoamino, and bisamino substituted carbamates along with BPA in ratio of 1:2: 1 ratio respectively (Table 1, Entry 1). The product structures (3a, 4a and 5a) were confirmed by x-ray crystallography.

[0074] Various bases were screened in order to increase the selectivity. The screening was performed in the presence of organic as well as inorganic bases but the selectivity of the product did not changed (Table 1, Entry 2-3). Surprisingly, when the reaction was performed in the absence of base, similar results were obtained (Table 1, Entry 5). This indicated that no external additive was required. Increasing or decreasing the solvent concentration to 0.78 M and 0.19 M respectively did not alter the reaction rate (Table 1, Entry 6-7).

[0075] The concentration of the amine was slightly changed. This resulted in changes in the product yield, however ratio of the products was maintained irrespectively (Table 1, Entry 8-9). With other solvents such as acetone, THF and 1,4 dioxane similar results were obtained (Table 1, Entry 10-11). Reactivities were good with all the four solvents, however, acetone was preferred as the solvent, considering it as a green solvent.

[0076] BPA-PC samples are selected from but not limited to (a) Disc, (b) Helmet, (c) Safety goggle, and d) Roof sheet. FIG. 1 illustrates the GPC data for real life polycarbonates. Table 1. Optimization table for aminolysis of polycarbonate

[0077] Reaction conditions: 1 (100 mg, 0.39 mmol, 1 equiv), 2 (67.89 mg, 0.78 mmol, 2 equiv), base (0.11 mmol, 30 mol%), solvent 0.39 M, under air.awith 0.78M concentration,bwith 0.19M concentration,c0.39 mmol of 2,dl .17 mmol of 2.

[0078] After the reaction conditions were optimized, different secondary amines for the depolymerization of polycarbonate waste were explored and tested. Amines such as piperidine, pyrrolidine, azetidine, 4-methoxypiperidine, 4-phenylpiperidine, 2,5-dihydro- IH-pyrrole, thiomorpholine were tested and yielded good to excellent yields of carbamates along with BPA (FIG. 5; 2a-2h). The solubility issues were noticed when acetone was used as solvent for substrates like 2d, 2e, 2f. Later, DCM was used as solvent for substrates like 2d, 2e, 2f. Substrates 2d and 2f gave the product distribution in 1: 1: 1 ratio of BPA, mono and bisaminocarbamates respectively. The final products were separated through column chromatography except for final prodcuts from amines 2g and 2h.

[0079] Further, late stage functionalization with 9-chloro-6-(piperazin-l- yl)dibenzo[d,f][l,3]oxazepine (amoxapine) and 8-chloro-l l-(piperidin-4-ylidene)-6,l l- dihydro-5 / 7-bcnzo[5,6]cyclohcpta[L2-b]pyridinc (desloratadine) was conducted. These substrates resulted in products like other amines but with DCM as the reaction solvent (FIG. 5, 2i-2j).

[0080] Furthermore, depolymerization of different polycarbonate waste like laboratory safety goggle (Mn = 11368 g / mol, Mw = 19,922 g / mol) helmet (Mn = 15,730 g / mol, Mw = 28,930 g / mol) and roof sheet (Mn = 15,345 g / mol, Mw = 27,228 g / mol) was tested under the optimized conditions with the combination of morpholine as ideal aminolytic reagent. Good yields of carbamates and BPA (FIG. 6) was observed, which demonstrates the generality of the method to depolymerize the PC.

[0081] Later, the reaction was conducted at gram scale (3.9 mmol) in the laboratory using the waste CD disc. Under the optimized conditions complete depolymerization of the polycarbonate to carbamates and monomer BPA was achieved (FIG. 7). The bisaminocarbamate (5c) was further derivatized and subjected to the ort / zo-Fries rearrangement reaction which delivered the amides 6 and 7 with 22% and 50% of yields respectively (FIG. 8).

[0082] Accordingly, the present invention provides a simple and greener method for the depolymerization of end-of-life polycarbonates. The secondary amines facilitates the catalyst / additive free method for depolymerization of polycarbonate at ambient conditions. Variety of secondary amines were screened with real life PC to synthesize the virgin monomer BPA along with corresponding monoaminocarbamate and bisamionocarbamates. Various commercial amine derivatives were also employed for the depolymerization of PC. Further gram scale reaction and derivatization of the bisaminocarbamate to amides proves the potentiality of the method in chemical recycling of polycarbonates.

[0083] EXAMPLES:

[0084] Unless stated otherwise, all reactions were carried out under air in a 10 mL RB. Anhydrous grade solvents were used as such from the Spectrochem. All the reactions were monitored by analytical thin layer chromatography (TLC) using commercial aluminium sheets precoated with silica gel. Column chromatography was conducted on silica gel (Merck, 100-200 mesh). All other chemicals were received and used as such from the commercial sources. NMR spectra were recorded on Bruker Avance 400, 500 MHz instruments. NMR data have been reported as follows: chemical shift (d) in ppm, multiplicity (s = singlet, d = doublet, t = triplet, q =quartet, and m = multiplet), coupling constant (J) in Hz, and integration. Mass spectra were recorded on Thermo Scientific QExactive mass spectrometer, the column specification is Hypersil gold C18 column 150 * 4.6 mm diameter 8 pm particle size mobile phase used in acetonitrile and methanol. OMNISEC RESOLVE and OMNISEC REVEAL of Malvern Panalytical Instrument were used to determine the number average molecular weight (Mn), weight average molecular weights (Mw), and polydispersities (Mw / Mn). OMNISEC RESOLVE is a combined pump, degasser, autosampler and column oven for mobile phase delivery and sample injection. OMNISEC REVEAL is an integrated multi -detector. The Columns were eluted with THF at 30 °C at LOmL / min, column T6000 M General Mixed. The calibration curve was obtained using 12 monodisperse polystyrene standards. Example 1: Preparation of waste PC-BPA samples for experiment

[0085] The used PC-BPAs were obtained from compact disk, safety goggles, sun roof, and helmet. All samples were first cleaned of any external contamination by washing the surface thoroughly with soap and water, followed by acetone. The Compact Disk was then cut into small pieces with scissor and then dissolved in THF at 80 °C. Later, the dissolved polycarbonate was precipitated by hot filtration into excess methanol to remove impurities and additives. Other waste PC-BPA samples were dissolved in DCM and precipitated by pouring into methanol to remove impurities and additives.

[0086] Example 2: General procedure for conversion of waste PC-BPA to carbamates

[0087] An oven dried RB was charged with Teflon coated magnetic stir bar under air. Then, waste PC-BPA (1) (100 mg, 0.393 mmol, 1 equiv), morpholine (2) (70 mg, 0.8 mmol, 2 equiv) were added, followed by acetone (1 mL). The resultant reaction mixture was stirred in a closed system at room temperature for 1 h. Solvent was evaporated under reduced pressure and the crude reaction mixture was purified by flash column chromatography (EtOAc / Hexane) on silica gel afforded the BPA and carbamates as white solid.

[0088] Example 3: Preparation and Analytical data of the products i) 4,4'-(propane-2,2-diyl)diphenol (3a): Compound 3a was prepared according to the general procedure and purified by flash column chromatography (25% EtOAc / Hexane) yield 31% (26 mg) as a white solid.1H NMR

[0089] (400 MHz, CDCh) d 7.09 (m, 4H), 6.73 (m, 4H), 4.73 (s, 2H), 1.62 (s, 6H).13C NMR (101 MHz, CDCh) d 153.42, 143.47, 128.08, 114.85, 41.84, 31.21. HRMS-ESI (m / z): Calculated for C15H15O2 [M-H]’: 227.1071; Found: 227.1067.

[0090] Compound 4g, 5g and 4h, 5h were prepared along with 3a according to the general procedure and purified by flash column chromatography (30% EtOAc / Hexane) yield as a white solid, 80% (4g, 5g; 130 mg) and 76% (4h, 5h; 133 mg), respectively, in 1:2: 1 ratio.

[0091] HRMS-ESI (m / z): Calculated for (4g) C20H22NO3 [M+H]+: 324.1600; Found: 324.1604.

[0092] HRMS-ESI (m / z): Calculated for (5g) C25H27N2O4 [M+H]+: 419.1971; Found: 419.1965.

[0093] HRMS-ESI (m / z): Calculated for (4h) C20H24NO3S [M+H]+: 358.1477; Found: 358.1468. HRMS-ESI (m / z): Calculated for (5h) C25H31N2O4S2 [M+H]+: 487.1725; Found:

[0094] 487.1714. ii) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl morpholine-4-carboxylate (4a): l

[0095] 'H NMR (400 MHz, CDCh) d 7.22 - 7.18 (m, 2H), 7.09 - 7.05 (m, 2H), 7.01- 6.97 (m, 2H), 6.72 - 6.68 (m, 2H), 5.07 (s, 1H), 3.75-3.73 (m, 4H), 3.65-3.57 (m, 4H), 1.63 (s, 6H).

[0096] 3C NMR (101 MHz, CDCh) d 154.08, 153.67, 149.06, 148.25, 142.79, 128.10, 127.85, 121.07, 114.89, 66.80, 44.97, 44.24, 42.19, 31.17. HRMS-ESI (m / z): Calculated for

[0097] C20H24NO4 [M+H]+: 342.1705; Found: 342.1696 iii) propane-2, 2-diylbis(4,l-phenylene) bis(morpholine-4-carboxylate) (5a):

[0098] Com ound 5a was re ared accordin to the eneral solid.

[0099] 'H NMR (400 MHz, CDCh) 3 7.22- 7.19 (m, 4H), 7.02-6.98 (m, 4H), 3.75 - 3.73 (m, 8H), 3.65-3.57 (m, 8H), 1.65 (s, 6H).13C NMR (101 MHz, CDCh) 3 153.94, 149.20, 147.67, 127.89, 121.12, 66.77, 44.98, 44.24, 42.57, 31.13. HRMS-ESI (m / z): Calculated for C25H31N2O6 [M+H]+: 455.2182; Found: 455.2177. iv) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl piperidine-l-carboxylate (4b): al y

[0100] (30% EtOAc / Hexane) yield 47% (65 mg) as a white solid. 'H NMR (400 MHz, CDCh) <5 7.19-7.16 (m, 2H), 7.04 -6.96 (m, 4H), 6.65 - 6.62 (m, 2H), 6.06 (s, 1H), 3.59-3.51 (m, 4H), 1.63 (s, 6H), 1.61 (s, 6H).13C NMR (101 MHz, CDCh) <5 154.30, 154.04, 149.25, 148.11, 142.26, 127.93, 127.75, 121.16, 114.91, 45.64, 45.25, 42.12, 31.20, 26.01, 25.61, 24.39. HRMS-ESI (m / z): Calculated for C21H26NO3 [M+H]+: 340.1913; Found: 340.1907. v) propane-2, 2-diylbis(4,l -phenylene) bis(piperidine-l-carboxylate) (5b): Compound

[0101] 'H NMR (400 MHz, CDCI3) d 7.21-7.17 (m, 4H), 7.01 - 6.97 (m, 4H), 3.58-51 (m, 8H), 1.65 (s, 6H), 1.63-1.60 (m, 12H).13C NMR (101 MHz, CDCI3) d 153.99, 149.52, 147.38, 127.80, 121.19, 45.61, 45.23, 42.53, 31.17, 26.06, 25.64, 24.47. HRMS-ESI (m / z) Calculated for C27H35N2O4 [M+H]+: 451.2597; Found: 451.2591. vi) 4-(2-(4-hydroxyphenyl) propan-2-yl) phenyl pyrrolidine- l-carboxylate(4c): Compound 4c was prepared according to the general procedure and purified by flash column chromatography (15% EtOAc / Hexane) yield 49% (63 mg) as a white solid.

[0102] 'H NMR (400 MHz, CDCI3) 3 7.18 (d, J = 8.7 Hz, 2H), 7.08 (m, 4H), 6.72-6.67 (m, 2H), 5.15 (s, 1H), 3.55 (t, J = 6.5 Hz, 2H), 3.47 (t, J = 6.5 Hz, 2H), 1.97-1.90 (m, 4H), 1.62 (s, 6H).13C NMR (101 MHz, CDCI3) d 153.72, 153.60, 149.26, 147.87, 142.81, 128.09, 127.73, 121.18, 114.88, 46.59, 46.48, 42.17, 31.21, 25.94, 25.12. HRMS-ESI (m / z): Calculated for C20H24NO3 [M+H]+: 326.1756; Found: 326.1751. vii) propane-2, 2-diylbis(4,l-phenylene) bis(pyrrolidine-l-carboxylate(5c): Compound 5c was prepared according to the general procedure and purified by flash column chromatography (15% EtOAc / Hexane) yield 26% (43 mg) as a white solid.

[0103] 'H NMR (400 MHz, CDCI3) d 7.21-7.17 (m, 4H), 7.03-7.00 (m, 4H), 3.54 (t, J = 6.6 Hz, 4H), 3.47 (t, J= 6.6 Hz, 4H), 1.99-1.87 (m, 8H), 1.65 (s, 6H).13C NMR (101 MHz, CDCI3) <5 153.41, 149.38, 147.36, 127.79, 121.17, 46.55, 46.44, 42.52, 31.16, 25.94, 25.11. HRMS- ESI (m / z): Calculated for C25H31N2O4 [M+H]+: 423.2284; Found: 423.2256. viii) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenylazetidine-l-carboxylate (4d) : Compound 4d was prepared according to the general procedure using DCM as solvent and purified by flash column chromatography (20% EtOAc / Hexane) yield 33% (40 mg) as a white solid. 'H NMR (200 MHz, CDCh) d 7.20-7.14 (m, 2H), 7.10-6.96 (m, 4H), 6.74-6.66 (m, 2H), 5.06 (s, 1H), 4.18-4.11 (m, 4H), 2.39-2.24 (m, 2H), 1.62 (s, 6H).13C NMR (101 MHz, CDCh) d 153.59, 152.68, 148.79, 147.82, 142.63, 127.95, 127.63, 120.85, 114.75, 42.10, 42.02, 31.04, 15.74. HRMS-ESI ( / z): Calculated for C19H22NO3 [M+H]+: 312.1600; Found: 312.1594. ix) propane-2, 2-diylbis(4,l-phenylene) bis(azetidine-l-carboxylate) (5d): Compound 5d was prepared according to the general procedure using

[0104] DCM as solvent and purified by flash column chromatography (15% EtOAc / Hexane) yield 32% (49 mg) as a white solid.

[0105] 'H NMR (200 MHz, CDCh) d 7.21-7.16 (m, 4H), 7.03 - 6.95 (m, 4H), 4.14 (s, 8H), 2.39- 2.23 (m, 4H), 1.64 (s, 3H).13C NMR (101 MHz, CDCh) d 154.54, 149.08, 147.42, 127.82, 121.00, 50.34, 49.27, 42.51, 31.12, 15.88. HRMS-ESI ( / z): Calculated for C23H27N2O4 [M+H]+: 395.1971; Found: 395.1968. x) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl-4-methoxypiperidine-l-carboxylate yield 44% (64 mg) as a white solid.

[0106] 'H NMR (400 MHz, CDCh) d 7.20-7.16 (m, 2H), 7.06-7.02 (m, 2H), 6.99-6.95 (m, 2H), 6.71-6.65 (m, 2H), 5.99 (s, 1H), 3.89-3.83 (m, 2H), 3.48-3.41 (m, 1H), 3.38 (s, 4H), 3.37- 3.31 (m, 1H), 1.92-1.88 (m, 2H), 1.69-1.63 (m, 2H), 1.61 (s, 6H).13C NMR (101 MHz, CDCh) d 154.18, 153.99, 149.17, 148.16, 142.39, 127.99, 127.78, 121.11, 114.90, 75.52, 55.88, 49.74, 42.13, 41.82, 41.54, 31.18. HRMS-ESI ( / z): Calculated for C22H28NO4 [M+H]+: 370.2018; Found: 370.2013. xi) 4-(2-(4-((4-methoxycyclohexane-l-carbonyl)oxy)phenyl)propan-2-yl)phenyl 4- methoxypiperidine- 1 -carboxylate (5e) : purified by flash column chromatography

[0107] (30% EtOAc / Hexane) yield 23% (47 mg) as a white solid. 'H NMR (400 MHz, CDCI3) d 7.19 (d, J = 8.7 Hz, 4H), 6.98 (d, J = 8.7 Hz, 4H), 3.89- 3.83 (m, 4H), 3.47-3.41 (m, 2H), 3.38 (s, 6H), 3.33-3.31 (m, 4H), 1.93-1.88 (m, 4H), 1.68 - 1.65 (m, 7H), 1.63-1.61 (m, 3H).13C NMR (101 MHz, CDCI3) d 153.94, 149.40, 147.48, 127.83, 121.16, 75.51, 55.89, 42.54, 41.82, 41.53, 31.15, 30.85, 30.36. HRMS-ESI (m / z Calculated for C29H39N2O6 [M+H]+: 511.2808; Found: 511.2803. xii) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl 4-phenylpiperidine-l-carboxylate

[0108] 'H NMR (400 MHz, CDCI3) d 7.3-7.32 (m, 2H), 7.25-7.18 (m, 5H), 7.08-7.00 (m, 4H), 6.71 - 6.66 (m, 2H), 5.30 (s, 1H), 4.42 (s, 2H), 3.11-2.91 (m, 2H), 2.74 (tt, J = 12.1, 3.5 Hz, 1H), 1.92 (d, J = 13.1 Hz, 2H), 1.75 (ddd, 7 = 25.8, 12.8, 4.3 Hz, 2H), 1.63 (s, 6H).13C NMR (101 MHz, CDCI3) d 154.17, 153.78, 149.28, 148.08, 145.48, 142.67, 128.74, 128.06, 127.80, 126.91, 126.65, 121.17, 114.90, 45.34, 45.00, 42.67, 42.18, 33.49, 32.99, 31.20. HRMS-ESI (m / z) Calculated for C27H30NO3 [M+H]+: 416.2226; Found: 416.2220. xiii) propane-2, 2-diylbis(4,l-phenylene)bis(4-phenylpiperidine-l-carboxylate)(5f): yield 27% (65 mg) as a white solid.

[0109] 'H NMR (400 MHz, CDCI3) d 7.36-7.32 (m, 4H), 7.26-7.22 (m, 10H), 7.05-7.03 (m, 4H), 4.42 (s, 4H), 3.08-2.92 (m, 4H), 2.74 (tt, J = 12.1, 3.4 Hz, 2H), 1.93 (d, J = 12.9 Hz, 4H), 1.76 (ddd, J = 25.7, 12.8, 4.2 Hz, 4H), 1.67 (s, 6H).13C NMR (101 MHz, CDCI3) d 153.97, 149.47, 147.49, 145.53, 128.73, 128.03, 127.85, 126.90, 126.63, 121.20, 45.32, 44.98, 42.70, 42.56, 33.50, 33.02, 31.18. HRMS-ESI (m / z) Calculated for C39H43N2O4 [M+H]+: 603.3223; Found: 603.3217. xiv) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(9-chlorodibenzo[d,f][l,3]oxazepin-

[0110] 6-yl)piperazine-l-carboxylate (4i): Compound 4i was prepared according to the general . , . , , . , . , , . ,

[0111] J = 8.7 Hz, 1H), 7.23-7.18 (m, 3H), 7.12-7.08 (m, 2H), 7.05-7.01 (m, 5H), 6.69-6.65 (m, 2H), 3.72-3.57 (m, 8H), 1.59 (s, 6H).13C NMR (101 MHz, DMSO) 3 163.93, 163.27, 160.31, 158.35, 156.46, 153.97, 153.02, 145.53, 144.95, 138.37, 134.87, 134.01, 132.57,

[0112] 132.44, 131.77, 131.10, 129.70, 129.62, 128.38, 126.33, 125.46, 119.92, 46.63, 35.91. HRMS-ESI (m / z) Calculated for C33H3IC1N3O4 [M+H]+: 568.2003; Found: 568.1998. xv) propane-2, 2-diylbis(4,l-phenylene)bis(4-(9-chlorodibenzo[d,f][l,3]oxazepin-6- yl)piperazine-l -carboxylate) (5i): Compound 5i was prepared according to the general ,

[0113] 7.33 (dd, J = 8.6, 2.4 Hz, 2H), 7.26 (d, J = 2.3 Hz, 2H), 7.17-7.00 (m, 12H), 6.95- 6.92 (m, 6H), 3.70-3.63 (m, 8H), 3.51 (s, 8H), 1.58 (s, 6H).13C NMR (101 MHz, CDCI3) 3 159.49, 158.88, 153.98, 151.88, 149.20, 147.69, 139.92, 132.93, 130.56, 128.99, 127.89, 127.25, 125.98, 125.08, 124.96, 122.96, 121.15, 120.29, 47.41, 44.31, 43.78, 42.56, 31.11. HRMS- ESI ( / z): Calculated for C51H45CI2N6O6 [M+H]+: 907.2778; Found: 907.2772. xvi) 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(7-chloro-5,10-dihydro-llH benzo[4,5]cyclohepta[l,2-b]pyridin-ll-ylidene)piperidine-l-carboxylate (4j): EtOAc / Hexane) yield 34% (75 mg) as a white solid.

[0114] 'H NMR (400 MHz, DMSO) <5 9.21 (s, 1H), 8.35 (d, J = 3.7 Hz, 1H), 7.58 (d, J = 7.2 Hz, 1H), 7.31 (m, 1H), 7.23-7.11 (m, 5H), 7.00 (q, J = 4.5 Hz, 4H), 6.65 (d, J = 8.4 Hz, 2H), 3.81- 3.59 (m, 6H), 2.85-2.80 (m, 2H), 2.43-2.27 (m, 4H), 1.57 (s, 6H).13C NMR (400 MHz, DMSO) <5 158.71, 158.05, 155.09, 153.13, 151.24, 148.75, 147.80, 140.31, 139.73, 133.15, 129.65, 128.79, 127.35, 127.22, 126.55, 125.88, 124.48, 124.40, 123.16, 121.11, 120.24, 114.70, 46.44, 43.77, 43.16, 41.41, 30.69. HRMS-ESI (m / z): Calculated for C35H34CIN2O3 [M+H]+: 565.2258; Found: 565.2252. xvii) Propane-2, 2-diylbis(4,l-phenylene)bis(4-(8chloro5,6dihydro-llH benzo[5,6]cyclohepta[l,2-b]pyridin-ll-ylidene)piperidine-l-carboxylate)(5j):

[0115] (53 mg) as a white solid.

[0116] 'H NMR (400 MHz, CDC13) d 8.41 (d, J = 4.4 Hz, 2H), 7.45 (d, J = 7.6 Hz, 2H), 7.20- 7.09 (m, 12H), 6.98 (d, J = 8.6 Hz, 4H), 3.94-3.90 (m, 4H), 3.43-3.25 (m, 8H), 2.90-2.78 (m, 5H), 2.62-2.56 (m, 2H), 2.47-2.35 (m, 7H), 1.64 (s, 6H).13C NMR (101 MHz, CDCI3) <5 157.07, 153.90, 149.36, 147.53, 146.84, 139.66, 137.75, 137.11, 134.66, 133.51, 133.15, 130.65, 129.17, 127.83, 126.36, 122.50, 121.17, 49.57, 42.53, 31.82, 31.62, 31.13, 30.81. HRMS-ESI (m / z): Calculated for C55H5IC12N4O4 [M+H]+: 901.3287; Found: 901.3241.

[0117] Example 5: Gram Scale reaction and production of value added products:

[0118] An oven dried RB was charged with Teflon coated magnetic stir bar under air. Waste PC- BPA (1000 mg, 3.93 mmol, 1 equiv), morpholine (696mg, 8 mmol, 2 equiv) were added, followed by acetone (10 m ). The resultant reaction mixture was stirred in a closed system at room temperature for 1 h. Solvent was evaporated under reduced pressure and the crude reaction mixture was purified by flash column chromatography (EtOAc / Hexane) on silica gel afforded the BPA, 42% (378 mg), 4a, 39% (530 mg), and 5a, 23% (423 mg) as white solid (FIG. 7). Example 6: Derivatization of bisaminocarbamate (5c)

[0119] In an oven dried Schlenk flask n-BuLi (0.6 mL , 3 equiv , 2M sol. in cyclohexane) was added dropwise to a stirred solution of diisopropylamine (121 mg , 1.2 mmol, 3 equiv), in anhydrous THF (1 mL) at -78 °C under a nitrogen atmosphere. After 20 min at -78 °C a solution of the appropriate carbomate (5c) (181 mg, 0.4 mmol, 1 equiv) in anhydrous THF (1 mL) was added. The reaction mixture was stirred for 30 min at -78 °C, later allowed to warm to room temperature and stirred for another 6 h. After the reaction time, quenched with sat. NH4CI and extracted with DCM. The organic layer was washed with brine (25 mL) and then dried using Na2SO4. The solvent was removed in vacuo and the crude product was purified by flash column chromatography (25% EtOAc / Hexane) on silica gel to give the corresponding amides 6 in 22% (30 mg) and 7 in 50% (90 mg) yield (FIG. 8).

[0120] (2-hydroxy-4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl)(piperidin-l-yl)methanone) (6): Obtained as white solid. 'H NMR (200 MHz, CDCh) 3 9.47 (s, 1H), 7.29-7.24 (m, 1H), 7.08 (d, J = 8.7 Hz, 2H), 6.96- 6.89 (m, 2H), 6.77-6.69 (m, 2H), 4.99 (s, 1H), 3.53-3.48 (m,

[0121] 4H), 1.61 (s, 8H), 1.54-1.51 (m, 4H).13C NMR (101 MHz, CDCh) 3 171.12, 156.85, 153.71, 142.89, 141.29, 130.48, 128.05, 127.34, 117.35, 116.64, 114.94, 47.05, 41.85, 31.05, 26.10, 24.66. HRMS-ESI ( / z): Calculated for C21H26NO3 [M+H]+: 340.1913; Found: 340.1907.

[0122] (propane-2, 2-diylbis(6-hydroxy-3,l-phenylene))bis(piperidin-l-ylmethanone) (7):

[0123] Obtained as white solid. 'H NMR (400 MHz, CDCh) <5 9.51 (s, 2H), 7.26-7.23 (m, 2H), 6.97 (d, J = 2.4 Hz, 2H), 6.92 (d, J = 8.6 Hz, 2H), 3.54-3.50 (m, 8H), 1.69-1.63 (m,

[0124] 4H), 1.62 (s, 6H), 1.56-1.50 (m, 8H).13C NMR (101 MHz, CDCh) 8 170.94, 157.10, 140.71, 130.52, 127.10, 117.54, 116.75, 47.06, 41.87, 30.93, 26.11, 24.63. HRMS-ESI ( / z): Calculated for C27H35N2O4 [M+H]+: 451.2597; Found: 451.2591.

[0125] Example 7: SC-XRD experiment

[0126] The single crystals of 3a, 4a and 5a components were obtained from DCM solvent, while the crystals of 3h obtained from the ethyl acetate solvent by slow evaporation method. The X-ray diffraction measurements were performed to determine the crystal structure of all the four components at 100 K using APEX3 (Bruker, 2016; Bruker D8 VENTURE Kappa Duo PHOTON II CPAD) diffractometer having graphite -monochromatized (MoKa = 0.71073 A). The X-ray generator was operated at 50 kV and 30 mA. A preliminary set of unit cell parameters and an orientation matrix were calculated from 36 frames, and the cell refinement was performed by SAINT-Plus (Bruker, 2016). An optimized strategy used for data collection consisted of different sets of cp and co scans with 0.5° steps cp / co. The data were collected with a time frame of 10 sec for both the components by setting the sample to detector distance fixed at 40 cm. All the data points were corrected for Lorentzian, polarization, and absorption effects using SAINT-Plus and SADABS programs (Bruker, 2016). SHELXS-97 (Sheldrick, 2008) was used for structure solution, and full-matrix least- squares refinement on F2.[1],[2]The molecular graphics of ORTEP diagrams were performed by Mercury software. The crystal symmetry of the components was cross-checked by running the cif files through PLATON (Spek, 2020) software and notified that no additional symmetry was observed. The Encifer software was used to correct the cif files.

[0127] FIG. 2-4 disclose the ORTEP diagram of compounds 3a, 4a and 5a, wherein the asymmetric unit contains a single molecule.

[0128] Table 2. Crystallographic information details of compounds 3a, 4a and 5a. Table 3. Hydrogen-bond geometry (A°, °) of 3a, 4a and 5a components are given as below.

[0129] ADVANTAGES OF THE PRESENT INVENTION i. The present disclosure provides a process of conversion of polycarbonate (PC) based wastes into value added products by depolymerization. ii. The present disclosure provides a process for depolymerizing the polycarbonate waste to bisphenol A, monoaminocarbamate and bisaminocarbamate. iii. The present disclosure provides a process of conversion of polycarbonate (PC) based wastes that is catalyst free, additive free. iv. The present disclosure provides a process of conversion of polycarbonate (PC) based wastes into value added products by depolymerisation by treating polycarbonate waste with secondary amine (R2NH; R = alkyl, aryl, heteroaryl), under mild conditions covering a solvent, room temperature and in an open air for time period in the range of 30 to 90 minutes to obtain value added products. v. The present disclosure provides a metal free method that works with greener solvent and avoids high temperature, super stoichiometric amount of additives or reagents. vi. The present disclosure provides a method that not only enhances energy efficiency but also facilitates the recovery of raw materials with 100% atom economy, aligning with the principles of life cycle assessment.

[0130] Although the present invention has been described with reference to preferred embodiments, it is submitted that various modifications can be made to the exemplary embodiments without departing from the spirit and scope of the invention.

Claims

We Claim:

1. A process for preparation of value added products by depolymerization of a polycarbonate, comprising: reacting the polycarbonate with a secondary amine as an aminolytic agent in presence of a solvent at temperature in the range of 25-30 °C for a time period in the range of 30-90 minutes to obtain the value added products; wherein the process is a catalyst free and additive free process.

2. The process as claimed in claim 1, wherein the value added products are selected from bisphenol A [4,4'-(propane-2,2-diyl)diphenol], monoaminocarbamate and bisaminocarbamate or combination thereof.

3. The process as claimed in claim 1, wherein the value added products are selected from: i. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl morpholine-4-carboxylate (4a), ii. propane-2, 2-diylbis(4,l -phenylene) bis(morpholine-4-carboxylate) (5a), iii. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl piperidine- 1 -carboxylate (4b), iv. propane-2, 2-diylbis(4,l -phenylene) bis(piperidine-l-carboxylate)(5b), v. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl pyrrolidine- 1 -carboxylate (4c), vi. propane-2, 2-diylbis(4, 1 -phenylene) bis(pyrrolidine- l-carboxylate(5c), vii. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl azetidine- 1 -carboxylate (4d), viii. propane-2, 2-diylbis(4,l -phenylene) bis(azetidine- 1 -carboxylate) (5d), ix. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl-4-methoxypiperidine-l -carboxylate (4e), x. 4-(2-(4-((4-methoxycyclohexane- l-carbonyl)oxy)phenyl)propan-2-yl)phenyl 4- methoxypiperidine- 1 -carboxylate (5e), xi. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl 4-phenylpiperidine-l -carboxylate (4f), xii. propane-2, 2-diylbis(4,l -phenylene) bis(4-phenylpiperidine-l -carboxylate) (5f), xiii. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(9-chlorodibenzo[d,f][l,3]oxazepin- 6-yl)piperazine- 1 -carboxylate (4i) , xiv. propane-2, 2-diylbis(4,l -phenylene) bis(4-(9-chlorodibenzo[d,f][l,3]oxazepin-6- yl)piperazine- 1 -carboxylate) (5i), xv. 4-(2-(4-hydroxyphenyl)propan-2-yl)phenyl4-(7-chloro-5,10-dihydro-l lH benzo[4,5]cyclohepta[l,2-b]pyridin-l l-ylidene)piperidine-l -carboxylate (4j), and xvi. Propane-2,2-diylbis(4,l-phenylene)bis(4-(8-chloro-5,6-dihydro-l l-H- benzo[5,6]cyclohepta[l,2-b]pyridin-l l-ylidene)piperidine-l-carboxylate)(5j).

4. The process as claimed in claim 1, wherein the secondary amine is selected from cyclic secondary amine, and derivatives thereof.

5. The process as claimed in claim 4, wherein the cyclic secondary amine is selected from piperidine, pyrrolidine, azetidine, 4-methoxypiperidine, 4-phenylpiperidine, 2,5-dihydro- IH-pyrrole, and thiomorpholine or any combination thereof.

6. The process as claimed in claim 1, wherein the solvent is selected from dichloromethane (DCM), acetone, tetrahydrofuran (THF), 1,4 dioxane, and ethyl acetate, or mixture thereof.

7. The process as claimed in claim 1, wherein the process optionally comprises a base.

8. The process as claimed in claim 7, wherein the base is selected from cesium carbonate (CS2CO3), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), tripotassium phosphate (K3PO4), and potassium tert-butoxide (KOtBu), or combination thereof9. The process as claimed in claim 1, wherein the polycarbonate is a waste polycarbonate based on a material selected from waste CD disc, helmet, laboratory safety goggle, and roof sheet.

10. The process as claimed in claim 1, wherein yield of the bisphenol A is in range of 22-32%, yield of the monoaminocarbamate is in range of 65-72%, and yield of the bisaminocarbamate is in range of 40 to 50%.

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