Foreword
Teaching organic chemistry is a difficult task. One reason is the large gap between
the observable properties of a given chemical species and its formal representation
on a blackboard or on a computer screen. This concern is even more important in
the case of the elucidation of reaction mechanisms, since it involves entities such
as reaction intermediates or transition states which are difficult, if not impossible,
to observe. The second (obvious) reason is that organic chemistry is an experimental science. We do not have in our discipline any “theorem of stereocontrol”
for example, although we have experimental data and mechanistic models that
provide us with conceptual tools to explain or even to predict the stereocontrol of
a new experiment in organic chemistry. Therefore, according to Popper, we cannot
demonstrate that a given mechanism is “true” although we can conclude that it is
“false” if it is not compatible with the experimental observations. In addition, the
concept of reaction mechanism can be misleading because in many textbooks it is
implicitly assumed that there is a common mechanism for, let us say the Diels Alder-reaction although we know that any cycloaddition can be stepwise or concerned.
This book constitutes an innovative contribution within this context. The authors have collected very illustrative problems that cover the main topics of organic chemistry. However, they have not followed the usual admonitory way in
which only the correct answers are commented. Instead, the authors show the possible alternative mechanisms and how the experimental data provided by carefully
designed experiments can help to discard very plausible hypotheses.
In summary, the reader, after studying the problems presented and discussed in
this book, will appreciate not only the beauty and diversity of organic chemistry,
but also the necessity of being creative and (reasonably) unbiased as well as scepa a
tical and cautious when confronted with novel mechanistic problems.
University of the Basque Country, June 2003
Fernando P. Cossío
Teaching organic chemistry is a difficult task. One reason is the large gap between
the observable properties of a given chemical species and its formal representation
on a blackboard or on a computer screen. This concern is even more important in
the case of the elucidation of reaction mechanisms, since it involves entities such
as reaction intermediates or transition states which are difficult, if not impossible,
to observe. The second (obvious) reason is that organic chemistry is an experimental science. We do not have in our discipline any “theorem of stereocontrol”
for example, although we have experimental data and mechanistic models that
provide us with conceptual tools to explain or even to predict the stereocontrol of
a new experiment in organic chemistry. Therefore, according to Popper, we cannot
demonstrate that a given mechanism is “true” although we can conclude that it is
“false” if it is not compatible with the experimental observations. In addition, the
concept of reaction mechanism can be misleading because in many textbooks it is
implicitly assumed that there is a common mechanism for, let us say the Diels Alder-reaction although we know that any cycloaddition can be stepwise or concerned.
This book constitutes an innovative contribution within this context. The authors have collected very illustrative problems that cover the main topics of organic chemistry. However, they have not followed the usual admonitory way in
which only the correct answers are commented. Instead, the authors show the possible alternative mechanisms and how the experimental data provided by carefully
designed experiments can help to discard very plausible hypotheses.
In summary, the reader, after studying the problems presented and discussed in
this book, will appreciate not only the beauty and diversity of organic chemistry,
but also the necessity of being creative and (reasonably) unbiased as well as scepa a
tical and cautious when confronted with novel mechanistic problems.
University of the Basque Country, June 2003
Fernando P. Cossío