Alkylation of D-Aspartic acid; R,R-Ethylenediaminedisuccinic acid
SyntheticPage 297
DOI:
10.1039/SP297
Submitted Aug 28, 2008, published Aug 28, 2008
Chemicals Used
D-Aspartic acid (Aldrich)
Ca(OH)2
NaOH (50% aqueous w/v)
1,2-dibromoethane
Procedure
D-aspartic acid (6.083 g, 0.045 mol), Ca(OH)2 (1.653 g, 0.023 mol), NaOH (50% aqueous w/v, 3.60 g), and deionized water (8.5 ml) were placed in a 3-necked round bottom flask, and fitted with a water condenser. 1,2-dibromoethane (1.6 ml, 3.47 g, 0.018 mol) was added through one of the side arms. The reaction mixture was heated to reflux. Over approximately 6 h NaOH (50% aqueous w/v, 2.98 g) was added dropwise using a syringe pump, whilst under reflux. Water (20 ml) was added, and the system refluxed for a further hour. The system was cooled to room temperature, then acidified to pH 3 using HCl (35%). A white precipitate was collected and was placed in water (23 ml). NaOH (50% aqueous w/v) was added until pH 11, then HCl (35%) was added carefully until pH 3.5. The white precipitate was collected, and dried under vacuum at 65 °C. Yield: 1.417 g, 26%
Author's Comments
The aspartic acid is used in excess to the dibromoethane, there should be a 2:1 stoichiometry.During the addition of NaOH over 6 h the pH of the reaction mixture is best between pH 9-13. The crude product will include many side products and the unreacted aspartic acid. Since aspartic acid is more soluble in water, it should remain in solution during the recrystallisation.
Data
H-NMR (300MHz, D2O/NaOH) 2.24 (dd, 2H, 3JHH=8.0Hz, 2JHH=15.1Hz, CH2COO), 2.41 (dd, 2H, 3JHH=5.7Hz, 2JHH=15.1Hz, CH2COO), 2.53 (m, 2H, CH2CH2), 3.29 (dd, 2H, 3JHH=5.7Hz, 3JHH=8.0Hz), 4.79 (solvent peak D2O/NaOH);C-NMR (D2O/NaOH): 41.3 (CH2-CH2 or CH2COO), 46.6 (CH2-CH2 or CH2COO), 61.3 (CH), 179.8 (COO quaternary), 181.5 (COO quaternary); ESI Positive m/z 293.09 ([EDDS + H]+)
Lead Reference
J. A. Neal and N. J. Rose,
Inorg. Chem., 1968,
7, 2405-2412
doi:10.1021/ic50069a043
Other References
A.Damiamoglou et al. A New Reference Material for UV-visible Circular Dichroism Spectroscopy, Chirality, 2008.
doi:10.1002/chir.20566Personal communications from Jim Barker, Innospec
Supplementary Information
The
S,
S-isomer of this compound (known as EDDS) is manufactured by Innospec under the trade name octaquest as a biodegradable alternative to EDTA in
e.g. microelement fertilisers and detergents, photographic processing or as molluscicide. The
R,
R-isomer is not readily biodegradable.
C13NMR spectrum of R,R-Ethylenediaminedisuccinic acid
HNMR Spectrum of R,R-Ethylenediaminedisuccinic acid
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Keywords: amino acids, aspartic acid, dibromoethane, nucleophilic, substitution