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|Title:||Structures of L-lactic acid chloralide, D-malic acid chloralide and L-malic acid chloralide|
|Authors:||Z. Pang, W.|
H. Huang, H.
L. Koh, L.
Lactic acid chloralide
Malic acid chloralide
|Citation:||Z. Pang, W.,H. Huang, H.,L. Koh, L. (1997-08-11). Structures of L-lactic acid chloralide, D-malic acid chloralide and L-malic acid chloralide. Journal of Molecular Structure 415 (1-2) : 17-28. ScholarBank@NUS Repository. https://doi.org/10.1016/S0022-2860(97)00096-3|
|Abstract:||The crystal and molecular structures of L-lactic acid chloralide and L-malic acid chloralide have been determined by X-ray diffraction methods. L-lactic acid chloralide crystallises in the monoclinic space group, p21/c, a = 7.650 (3), b = 5,856 (2), c = 9.808 (4) ',β = 99.64 (3)°, Z= 2. L-malic acid chloralide crystallizes in the monoclinic space group, p21/c, a = 10.456 (2), b=5.818(10),c=16.638 (3) ',β=94.76 (2)°, Z=4. The five-membered ring system of these compounds is slightly twisted out-of-plane. The CCI3 group is trans to the CCH3 group in L-lactic acid chloralide and to the CH2COOH group in the L-malic acid chloralide. The IR spectra of L-malic acid chloralide and D-malic acid chloralide are discussed in relation to the structures of these compounds. The chemical shifts of the protons on the C5 position in the compounds are about 4.83 ppm in λ-lactic acid chloralide, and 4.89 ppm in L-malic acid chloralide and D-malic acid chloralide respectively. These values show that the conformations of these compounds are trans-substitutions. The long-range coupling constant (J(Ir) = 1.37 to 1.68 Hz) between the cross-ring protons (on C2 and C5) in the five-membered ring structure of chloralides confirms that the conformations of the compounds are transforms (in cis-forms, J(Ir) = 1.1 Hz). The geminal coupling between two protons on the methylene (-CH2COOH) of the malic acid chloralides may be the result of intramolecular hydrogen bonding which hinders the C-C bond between the CH(ring) and CH2COOH from rotating freely and causes the two protons on the CH2COOH group to have different chemical environments.|
|Source Title:||Journal of Molecular Structure|
|Appears in Collections:||Staff Publications|
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