Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.
A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates.
Catalysis Research Laboratory (CaRLa), Im Neuenheimer Feld 584, 69120, Heidelberg, Germany.
Nicolas
N
Germain
BASF SE, Carl-Bosch-Str. 38, 67056, Ludwigshafen, Germany.
Imke
I
Müller
BASF SE, Carl-Bosch-Str. 38, 67056, Ludwigshafen, Germany.
Matthias
M
Hanauer
BASF SE, Carl-Bosch-Str. 38, 67056, Ludwigshafen, Germany.
Rocco A
RA
Paciello
BASF SE, Carl-Bosch-Str. 38, 67056, Ludwigshafen, Germany.
Robert
R
Baumann
Catalysis Research Laboratory (CaRLa), Im Neuenheimer Feld 584, 69120, Heidelberg, Germany.|Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120, Heidelberg, Germany.
Oliver
O
Trapp
Catalysis Research Laboratory (CaRLa), Im Neuenheimer Feld 584, 69120, Heidelberg, Germany. thomas.schaub@basf.com.|BASF SE, Carl-Bosch-Str. 38, 67056, Ludwigshafen, Germany. thomas.schaub@basf.com.
Thomas
0000-0003-2332-0376
T
Schaub
D000438:Alcohols / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic; D007221:Industry; D017953:Isocyanates / Q000737:chemistry*; D009947:Organotin Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D048448:Phenylcarbamates / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory
D000438:Alcohols; D017953:Isocyanates; D009947:Organotin Compounds; D048448:Phenylcarbamates; D002245:Carbon Dioxide; D010100:Oxygen
carbamates; carbon dioxide; isocyanates; polymers; tin