Linked Life Data

9548905

Source:http://linkedlifedata.com/resource/pubmed/id/9548905

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1998-6-10
pubmed:abstractText
From the known crystal structure of aspartame hemihydrate, designated form 1, the theoretical powder X-ray diffraction (PXRD) pattern was calculated. This PXRD pattern differs significantly from that of the commercially available aspartame hemihydrate, which is therefore a different polymorph, designated form II. Form II transforms to form I during ball-milling or on heating for 30 min at 160 degrees C in the presence of steam. The two polymorphs were compared by PXRD, differential scanning calorimetry, thermogravimetric analysis, Karl Fischer titrimetry, Fourier transform infrared (FTIR) absorption spectroscopy, 13C solid-state nuclear magnetic resonance (SSNMR) spectroscopy, scanning electron microscopy, particle size analysis, and measurements of true density and intrinsic dissolution rate. Comparison of the 13C SSNMR and FTIR spectra of the two polymorphs suggests that the crystal structure of form II is less symmetric, with the side chains located in multiple environments. Although both hemihydrate polymorphs on heating in the absence of moisture dehydrate to a crystalline anhydrate, form I does so at a lower temperature, suggesting weaker interactions of water with aspartame molecules. At higher temperatures the anhydrate from both hemihydrate polymorphs yields 3-(carboxymethyl)-6-benzyl-2,5-dioxopiperazine (DKP) by a cyclization reaction for which the temperature, reaction enthalpy, and activation energy are very similar. Both hemihydrate forms, when in contact with liquid water, yield the 2.5-hydrate.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-3549
pubmed:author
pubmed:issnType
Print
pubmed:volume
87
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
501-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Solid-state characterization of two polymorphs of aspartame hemihydrate.
pubmed:affiliation
Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis 55455-0343, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't