Crystal structure and physical characterization of neotame methanol solvate

Zedong Dong, Victor G. Young, Brian E. Padden, Steve A. Schroeder, Indra Prakash, Eric J. Munson, David J.W. Grant

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The crystal structure of the methanol solvate (empirical formula: 2C20H30N2O5·3CH3OH ) of a new dipeptide sweetener, neotame (N-(3,3-dimethylbutyl)-L-α-aspartyl-L-phenylalanine 1-methyl ester), has been determined. Crystal data: a = 9.8989(1), b = 18.1331(1), c = 27.5725(1) Å, orthorhombic, space group P212121, with Z = 4. Each unit cell includes 8 neotame and 12 methanol molecules. Disorder exists in one neotame molecule and one methanol molecule. The crystals were characterized by the following techniques: hot-stage microscopy (HSM), Karl-Fischer titrimetry (KFT), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), 13C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Under HSM at a heating rate of 10°C/min in silicone oil, the sample melts at 64-84°C and liberates bubbles at 71-86°C. DSC in open pans shows two overlapping endotherms at 56 and 71°C, probably due to melting and desolvation, respectively. TGA in open pans shows 5.9% weight loss due to desolvation below 70°C. Under house vacuum (23 mm Hg) over phosphorus pentoxide at 23°C, the methanol solvate produces pure amorphous anhydrate, which converts to crystalline neotame monohydrate in the presence of moisture.

Original languageEnglish (US)
Pages (from-to)967-975
Number of pages9
JournalJournal of Chemical Crystallography
Issue number8
StatePublished - Aug 1999


  • C solid-state nuclear magnetic resonance spectroscopy
  • Crystal structure
  • Methanol solvate
  • Neotame
  • Powder x-ray diffractometry
  • Thermal analysis


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