(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date WO 2017/137343 Al 17 August 2017 (17.08.2017) P O P C T (51) International Patent Classification: (81) Designated States (unless otherwise indicated, for every C07C 269/04 (2006.01) C07C 271/24 (2006.01) kind of national protection available): AE, AG, AL, AM, C07C 271/12 (2006.01) AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, (21) Number: International Application DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, PCT/EP20 17/0525 10 HN, HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KH, KN, (22) International Filing Date: KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, 6 February 2017 (06.02.2017) MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, (25) Filing Language: English RU, RW, SA, SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, (26) Publication Language: English TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (30) Priority Data: 102016000013938 (84) Designated States (unless otherwise indicated, for every 11 February 2016 ( 11.02.2016) IT kind of regional protection available): ARIPO (BW, GH, GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, (71) Applicant: COVESTRO DEUTSCHLAND AG TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, [DE/DE]; Kaiser-Wilhelm-Allee 60, 51373 Leverkusen TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, (DE). DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, (72) Inventors: VINH, Trieu; Grabengasse 6, 50679 Koln SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, (DE). RICHTER, Frank; Heymannstr. 40, 51373 GW, KM, ML, MR, NE, SN, TD, TG). Leverkusen (DE). FEROCI, Marta; Via Pandolfo 1,8, 00162 Rom (IT). FORTE, Gianpiero; Via Appia Sud II Declarations under Rule 4.17 : trav., 2, 04023 Formia (FT). INESI, Achille; Via Antelao, — as to applicant's entitlement to apply for and be granted a 9, 0014 1 Rom (IT). CHIAROTTO, Isabella; Via Vin- patent (Rule 4.1 7(H)) cenzo Padula, 5, 00137 Rom (IT). Published: (74) Agent: LEVPAT; Covestro AG, Gebaude 4825, 51365 Leverkusen (DE). — with international search report (Art. 21(3)) (54) Title: SUSTAINABLE SYNTHESIS OF CARBAMATE COMPOUNDS (57) Abstract: A method for the production of carbamate compounds comprises the steps of: A) reacting an organic primary amine — with an organic halogen compound in the presence of a quaternary organic ammonium carbonate and/or bicarbonate, thereby obtain - ing a reaction mixture comprising a carbamate compound and a quaternary organic ammonium salt; B) separating the quaternary or- ganic ammonium salt from the reaction mixture obtained after step A); C) contacting the quaternary organic ammonium salt obtained after step B) with a carbonate and/or bicarbonate anion-exchange resin, thereby obtaining a quaternary organic ammonium carbonate and/or bicarbonate; D) repeating step A) at least once, wherein the quaternary organic ammonium carbonate and/or bicarbonate em- ployed in this next step A) is at least partially sourced from the quaternary organic ammonium carbonate and/or bicarbonate obtained from the preceding step C). Sustainable synthesis of carbamate compounds The present invention relates to a method for the production of carbamate compounds in which an organic amine is reacted with an organic halogen compound in the presence of a quaternary organic ammonium bicarbonate, thereby obtaining a reaction mixture comprising a carbamate compound and a quaternary organic ammonium salt. Several chemical routes for the production of O-alkyl carbamates as precursors for isocyanates are known, e.g. by reaction of primary amines with urea as the carbonyl source and an alcohol and evolution of ammonia. Efforts have also been made to use CO2 directly as the carbonyl source which is favorable since CO2 is available as sustainable raw material and no ammonia is produced as a side-product. Tetrahedron 1992, 48, 1515-1530 discloses that O-alkyl carbamates can be synthesized directly with CO2 with primary amines and an alkyl halide in presence of crown ether. However, the use of crown ether is impractical to use on a large scale for price reasons, and the reported maximum yield reached only 57%. Higher yields could be obtained under harsher conditions such as high pressure (J. Org. Chem, 1995, 60, 2820-2830) or electrochemical activation (Appl. Organometal. Chem. 2007, 21, 941- 944). However, this is also impractical to use on a large scale, since special equipment is required. A process under mild conditions is preferred. Another example for an electrochemical process is the Italian patent application RM2014A000694, filed on November 28, 2014 which discloses an electrochemical process for preparing bis-O-alkyl- carbamates from primary diamines with CO2 as carbonyl source, characterized in that at least one alkyl halide with at least 3 C-atoms in the alkyl group is used as alkylating agent in the presence of at least one iodide source and that the process is carried out at 10 to 215 °C. CO2 can be used indirectly under mild conditions when carbonate or bicarbonate salts are used as the carbonyl source. Carbonates or bicarbonates are easily accessible by reaction of CO2 in alkaline aqueous solution. It has been reported that O-alkyl carbamates can be obtained from aliphatic and aromatic amines with alkyl halide and cesium carbonate in presence of tetra-butyl ammonium iodide (WO 2002/034698 A2). However, the use of cesium and tetra-butyl ammonium iodide is unfavorable on a large scale for cost reasons, and the synthesis is preferably performed in dimethylformamide, which is unfavorable for toxicological reasons. Another synthesis route uses tetraethylammonium bicarbonate as carbonyl source. Using amines and alkyl halides in presence of tetraethyl ammonium bicarbonate under mild conditions results in high yields up to 98% for linear (J. Org. Chem. 1998, 63, 1337-1338) and cyclic carbamates (Synthesis 2010, 6, 943-946). For linear carbamates alkylating agents based on bromide, iodide, and tosylate have been employed in a large excess, typically 3 to 5 fold over amine, which makes this processes particularly unattractive in view of the high price of these alkylating agents. A general reaction sequence starting from an organic amine, a bicarbonate and an organic chloride is: + → + R-NH 2 + Y HC0 3 + Cl-R' R-NH-C(=0)-0-R' + Y C + H20 with R and R' being organic radicals and Y+ being an organic ammonium cation. Anionic exchange resins are known in the art. They can also be modified to serve as a source for hydrogen carbonate (bicarbonate) ions. US 2,999,821 relates to a method for removing chloride and silicate anions from a styrene-divinylbenzene quaternary ammonium anion-exchange resin which has at least one of said anions on the resin's ion-exchange sites, said method comprising treating the anion-exchange resin containing any chloride and silicate anions with an alkali metal bicarbonate, whereby said anions on the resin are replaced by bicarbonate ions and the resin is then capable of being used so as ultimately to take on more of said anions. WO 93/11071 Al discloses a method of producing an alkali metal carbonate comprising passing a solution or suspension of the chloride and the bicarbonate of the alkali metal through a solid ion exchange resin which in the aqueous environment is chloride retaining and has a basicity greater than that of the bicarbonate ion, and recovering an aqueous solution or suspension of the alkali metal carbonate from the resin. With respect to the synthesis of organic liquids, the publication Bull. Mater. Sci. 2013, 36, 1121- 1125 describes that salts were obtained by reacting tetraethylammonium cation [ + 2222] with inorganic anions like BF , NO 3, NO_ 2, SCN , BrO 3, IO 3, PF and HCO 3 using ion exchange methods. These ionic liquids (ILs) were characterized using thermal methods, infrared spectroscopy and densitometry. The present invention has the object of providing a process for producing O-alkyl carbamates that can also be conducted on an industrial scale with a recycling method for the quaternary ammonium salt. According to the invention this object is achieved by a method for the production of carbamate compounds, the method comprising the steps of: A) reacting an organic primary amine with an organic halogen compound in the presence of a quaternary organic ammonium carbonate and/or bicarbonate, thereby obtaining a reaction mixture comprising a carbamate compound and a quaternary organic ammonium salt; B) separating the quaternary organic ammonium salt from the reaction mixture obtained after step A); wherein the method further comprises the steps of: C) contacting the quaternary organic ammonium salt obtained after step B) with a carbonate and/or bicarbonate anion-exchange resin, thereby obtaining a quaternary organic ammonium carbonate and/or bicarbonate; D) repeating step A) at least once, wherein the quaternary organic ammonium carbonate and/or bicarbonate employed in this next step A) is at least partially sourced from the quaternary organic ammonium carbonate and/or bicarbonate obtained from the preceding step C). In step A) of the method according to the reaction an organic amine is brought to react with an organic halogen compound and a carbonate and/or bicarbonate as the carbonyl source. As a result, a carbamate is formed and the halogen of the organic halogen compound used as a starting material forms a halogenide salt with the organic ammonium compound.