Ammonium carbamate type self-derivative salts of (R-)- and racemic alpha-methylbenzylamine

作者：Madarasz Janos^*; Szekely Edit; Halasz Judit; Bansaghi Gyorgy; Varga Daniel; Simandi Bela; Pokol Gyoergy

来源：Journal of Thermal Analysis and Calorimetry, 2013, 111(1): 567-574.

DOI：10.1007/s10973-011-2174-5

• X-ray diffraction (XRD)
• FTIR spectroscopy
• Mass spectrometry (MS)
• Differential scanning calorimetry (DSC)
• Simultaneous TG/DTA
• Evolved gas analysis (EGA)
• TG/DTA-MS
• TG-FTIR

Two different compounds have formed from liquid enantiomeric (R-) and racemic alpha-methylbenzylamine (alpha-MBA, named also as 1-phenylethylamine, 1-FEA) with supercritical fluid CO2. The crystalline solids have been characterized by elemental CHN analysis, X-ray diffraction (XRD), FTIR, H-1, and C-13 NMR spectroscopy, and found to be alpha-methylbenzylammonium alpha-methylbenzylcarbamate self-derivative ionic salts 1 (R/R) and 2 (rac RS), respectively, of the corresponding amines. Compound 2 (rac RS) has shown different XRD pattern from that of enantiomerically pure 1 (R/R), indicating a preferential formation of a 1:1 mixture of (R/S-) and (S/R-) or rather a racemate compound of (RS/SR-) ammonium carbamate salt (2 (rac RS)) from racemate. For thermal stability, the compounds have been checked by differential scanning calorimetry (DSC), simultaneous thermogravimetry and differential thermal analysis (TG/DTA), and in situ coupled evolved gas analysis by mass spectroscopy (TG/DTA-EGA-MS) and FTIR-gas cell (TG-FTIR). No melting point is observed because of the low thermal stability of the compounds. Decomposition stages are tried to be separated with using semi-closed (sealed with a pinhole on the top) crucibles, thus different evolution courses of CO2 and organic vapors could be followed by MS and FTIR spectroscopy. The alpha-MBA vapors themselves, evolved from open crucibles could be identified by FTIR-gas cell, while vapors up to m/z = 164 have been detected by MS from semi-closed Al crucible.

• 出版日期2013-1