Abnormal buffer region observed for silica attached 3-aminopropyltrimethoxysilane

CHED 343

O'dell Hicks, bell@tarleton.edu, Department of Chemistry, Geoscience, & Environmental Science, Tarleton State University, Box T-0540, Stephenville, TX 76402 and Peter T. Bell, bell@tarleton.edu, Department of Chemistry, Geosciences, & Environmental Science, Tarleton State University, Box T-0540, Stephenville, TX 76402.
Silica supported reagents have been extensively used in order to develop ‘green' chemistry methodologies, as well as simpler and faster purifications. A convenient method was sought to determine the extent of incorporation of 3-aminopropyltrimethoxysilane (AMPSi) onto silica gel through potentiometric titration. However, due to titration curve irregularities, the method appeared to not be a valid way of determining incorporation. The absence of a well behaved buffer region is rationalized by the presence of multiple pKa's due to different environments experienced by the attached amine.
 

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