Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea
Akardite II (AK-II, N-methyl-N′,N′-diphenylurea) is a well-known stabilizer for nitrocellulose (NC) propellants as it scavenges NOx. Currently, AK-II is produced using phosgene, a highly toxic gas. An alternative, two-step synthesis route is presented here that does not rely on phosgene. First, symm...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-01-01
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| Series: | Current Research in Green and Sustainable Chemistry |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666086522000789 |
| _version_ | 1828163867638759424 |
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| author | E.P. van Geest J.J.M.H. van den Elshout J.F. Zevenbergen A.E.D.M. van der Heijden |
| author_facet | E.P. van Geest J.J.M.H. van den Elshout J.F. Zevenbergen A.E.D.M. van der Heijden |
| author_sort | E.P. van Geest |
| collection | DOAJ |
| description | Akardite II (AK-II, N-methyl-N′,N′-diphenylurea) is a well-known stabilizer for nitrocellulose (NC) propellants as it scavenges NOx. Currently, AK-II is produced using phosgene, a highly toxic gas. An alternative, two-step synthesis route is presented here that does not rely on phosgene. First, symmetrical organic carbonates (R2CO3, with R = Me, Et, or Ph) and diphenylamine react to form their corresponding carbamates in good yields for R = Me and Et (80% and 57%) and low yield for R = Ph (9%), catalyzed by 3-methyl-1-butylimidazolium chloride ([BMIM]Cl). The carbamate species are suggested to be formed in an equilibrium reaction. Evaporation of the alcohol side products pushes the equilibrium to the carbamate product. The second step converts the diphenyl carbamates into the targeted compound by treatment with (mono)methylamine (MMA), with reversed yield trend (4% for R = Me and Et, 81% for R = Ph). For the alkyl carbamates, the formation of AK-II appears to run in parallel with an MMA-alkylation reaction, which severely lowers the product yield. Overall, the synthesis of AK-II via the carbamate route is feasible, yet the carbonate side groups should be chosen carefully to obtain a high overall yield. |
| first_indexed | 2024-04-12T01:16:06Z |
| format | Article |
| id | doaj.art-fd0f5e567d4f48abbf867fb08983a7ca |
| institution | Directory Open Access Journal |
| issn | 2666-0865 |
| language | English |
| last_indexed | 2024-04-12T01:16:06Z |
| publishDate | 2022-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Current Research in Green and Sustainable Chemistry |
| spelling | doaj.art-fd0f5e567d4f48abbf867fb08983a7ca2022-12-22T03:53:57ZengElsevierCurrent Research in Green and Sustainable Chemistry2666-08652022-01-015100336Phosgene-free synthesis of N-methyl-N′,N′-diphenylureaE.P. van Geest0J.J.M.H. van den Elshout1J.F. Zevenbergen2A.E.D.M. van der Heijden3Netherlands Organization for Applied Scientific Research (TNO), Research Group Energetic Materials, Ypenburgse Boslaan 2, 2496 ZA, The Hague, the Netherlands; Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden, the NetherlandsNetherlands Organization for Applied Scientific Research (TNO), Research Group Energetic Materials, Ypenburgse Boslaan 2, 2496 ZA, The Hague, the NetherlandsNetherlands Organization for Applied Scientific Research (TNO), Research Group Energetic Materials, Ypenburgse Boslaan 2, 2496 ZA, The Hague, the NetherlandsNetherlands Organization for Applied Scientific Research (TNO), Research Group Energetic Materials, Ypenburgse Boslaan 2, 2496 ZA, The Hague, the Netherlands; Corresponding author.Akardite II (AK-II, N-methyl-N′,N′-diphenylurea) is a well-known stabilizer for nitrocellulose (NC) propellants as it scavenges NOx. Currently, AK-II is produced using phosgene, a highly toxic gas. An alternative, two-step synthesis route is presented here that does not rely on phosgene. First, symmetrical organic carbonates (R2CO3, with R = Me, Et, or Ph) and diphenylamine react to form their corresponding carbamates in good yields for R = Me and Et (80% and 57%) and low yield for R = Ph (9%), catalyzed by 3-methyl-1-butylimidazolium chloride ([BMIM]Cl). The carbamate species are suggested to be formed in an equilibrium reaction. Evaporation of the alcohol side products pushes the equilibrium to the carbamate product. The second step converts the diphenyl carbamates into the targeted compound by treatment with (mono)methylamine (MMA), with reversed yield trend (4% for R = Me and Et, 81% for R = Ph). For the alkyl carbamates, the formation of AK-II appears to run in parallel with an MMA-alkylation reaction, which severely lowers the product yield. Overall, the synthesis of AK-II via the carbamate route is feasible, yet the carbonate side groups should be chosen carefully to obtain a high overall yield.http://www.sciencedirect.com/science/article/pii/S2666086522000789N-Methyl-N′,N′-diphenylureaAkardite IIPhosgene-free synthesis |
| spellingShingle | E.P. van Geest J.J.M.H. van den Elshout J.F. Zevenbergen A.E.D.M. van der Heijden Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea Current Research in Green and Sustainable Chemistry N-Methyl-N′,N′-diphenylurea Akardite II Phosgene-free synthesis |
| title | Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea |
| title_full | Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea |
| title_fullStr | Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea |
| title_full_unstemmed | Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea |
| title_short | Phosgene-free synthesis of N-methyl-N′,N′-diphenylurea |
| title_sort | phosgene free synthesis of n methyl n n diphenylurea |
| topic | N-Methyl-N′,N′-diphenylurea Akardite II Phosgene-free synthesis |
| url | http://www.sciencedirect.com/science/article/pii/S2666086522000789 |
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