Relative basicity of porpholactones

CHED 1236

Michelle King, zenish1@yahoo.com, University of Connecticut Chemistry REU Program and, Central Connecticut State University, Department of Chemistry, P.O. Box 4010, New Britain, CT 06050, Guy Crundwell, crundwellg@ccsu.edu, Department of Chemistry, Central Connecticut State University, New Britain, CT 06050, and Christian Brückner, c.bruckner@uconn.edu, Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Unit 3060, Storrs, CT 06269-3060.
The meso-tetraarylporphyrins, such as 1, are known to be basic. Both imine-type nitrogens are capable of accepting two protons, resulting in the formation of a diprotonated macrocycle. The basicity is conceivably dependent on the nature of the meso-aryl groups. Porpholactones, such as 2, are porphyrin derivatives in which one β,β'- bond of 1 were formally replaced by lactone moieties. Porpholactones are, based on their UV-vis spectra, surprisingly similar to porphyrins. This contribution will describe an investigation of the relative basicity of variously meso-aryl substituted porphyrins and porpholactones in non-aqueous systems. The investigation reveals that the basicity of porpholactones is about two orders of magnitude weaker compared to the corresponding porphyrins. This effect is attributed to the reduced basicity of the imine functionality that is conjugated to the lactone carbonyl group. The influence of the meso-aryl groups was also determined.

 

Undergraduate Research Poster Session: Inorganic Chemistry
2:00 PM-4:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Chemical Education

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007