Organic Chemistry textbooks have long used the addition of HBr to 1,3-butadiene as a classic example of kinetic vs. thermodynamic control. At high temperatures the thermodynamically favorable 1,4-addition product predominates. At low temperatures, the less stable 1,2-addition product predominates. The traditional explanation for this is that the activation energy of the 1,2-addition is lower, thus its rate is faster. Some texts, citing a 1979 experiment by Eric Nordlander, are stating that the real reason is what is being called a proximity effect. We are currently charting and will report on the movement towards this explanation in textbooks. We are using experimental and computational methods to further refine the role the two explanations play in the reaction.

?Kinetic vs. thermodynamic control: Slow movement to a new paradigm

245th National Meeting (2013)

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