Authors:

Juliana Linder

Date Created:

Not specified

Course Title:

Professor:

Not specified

About Paper:

Lewis acids are used to activate carbonyls in a broad range of organic syntheses. In order to continue the development of novel reaction pathways and understand existing methods, it is necessary to determine the solution interactions between Lewis acids and bases, especially under catalytically relevant conditions. In this study, we performed in situ titrations coupled with in situ IR spectroscopy to observe Lewis acid/base equilibria, Lewis pairs, and aggregate complexes. Solution conductivity was also employed to measure the interaction of a range of acetophenones with iron(II) chloride. We observe data consistent with formation of iron(IIl)-centered complexes. Up to one equivalent of ketone, peak(s) consistent with the formation of a Lewis pair are observed. After one equivalent of ketone, peak(s) consistent with the formation of aggregate complexes are observed. Negligible conductance is observed when less than one equivalent of ketone is added to the.system, consistent with a Lewis pair. Beyond one equivalent of ketone, we observe conductance which is indicative of aggregate formation. Our data show that acetophenones with electron-donating substituents on the ring are more likely to form aggregate complexes with the catalyst. We also observed how the incorporation of fluorine atoms to the alpha position of acetophenone disrupts the formation of these aggregates. This collection of observations is intended to assist the synthetic chemist in the design of new catalysts and methods.

Source:

Loyola University Chicago

Topics:

No topics listed

Co-authors:

Juliana Linder