Linked Life Data

9548906

Source:http://linkedlifedata.com/resource/pubmed/id/9548906

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1998-6-10
pubmed:abstractText
Previous studies have shown that aspartame in the solid state can exist as a hemihydrate which occurs in two different polymorphic forms (I and II). The present work shows that equilibration of either hemihydrate at 25 degrees C with water vapor at relative humidities > or = 58% or with liquid water produces a 2.5-hydrate. Upon subjecting each of these crystalline hydrates to increasing temperature, the same crystalline anhydrate is formed which thermally cyclizes at a higher temperature to form the known compound 3-(carboxymethyl)-6-benzyl-2,5-dioxopiperazine. The activation energy of the cyclization reaction appears to depend on the degree of crystallinity of the anhydrate that is formed at a lower temperature. On increasing the temperature of the 2.5-hydrate, a hemihydrate intervenes before the anhydrate is formed. This intervening hemihydrate is similar to the commercial form (II) of aspartame hemihydrate but exhibits greater amorphous character. The techniques employed were Karl Fischer titrimetry, powder X-ray diffractometry, differential scanning calorimetry, thermogravimetric analysis, solid-state 13C nuclear magnetic resonance spectroscopy, and Fourier transform infrared absorption spectroscopy.
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
508-13
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Hydration and dehydration behavior 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