Try the next one oh o oh ho o h2o h oh h o o ho o h2o

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: two protons from acetic acid. The carboxylic acid proton is more acidic (pKa of 5) versus the alpha proton (pKa of 20). As a result, when confronted with the two possibilities, by pKa the top possibility happens and the bottom does not (or is VERY UNLIKELY). (There are some cases where pKa distances of 10 or more can be breached, but these involve slow reactions or high temperatures). Try the next one: OH O OH HO O H2O H OH H O O HO O H2O H OH H O OH HO O H2O H OH O OH HO O H2O H H 15 20 OH O O HO O H2O H H 15 15 OH O OH HO O H2O H 15 45 Hydroxide is much more likely to steal the proton from the hydroxyl group and not the alpha proton to the carbonyl. But it is still possible. As a result, the molecules in the top two rows can be present at the same time. It is always tempting to take the proton from the aldehyde. DO NOT DO IT! Aldehyde protons are not that acidic. There are specific reactions designed to take that specific proton away. These reactions are long and complicated. As a result, a mere base cannot take the proton away. Bronsted Acid- Base Mechanism: TA’s and Professors are sticklers for mechanism drawing. There is not a mechanism that you will draw more than the proton transfer mechanism. It consists of two arrows. The first arrow starts at the basic atom and goes to just before the proton. The second arrow starts at the bond between the acidic proton and the atom that it is attached to and goes to the atom the proton was attached to. ALWAYS DRAW IN THE H- A BOND. H OH O HO...
View Full Document

This note was uploaded on 02/14/2014 for the course CHEMISTRY 343 taught by Professor Clauss during the Spring '10 term at Wisconsin.

Ask a homework question - tutors are online