Integrated SequencePhysics Chemistry Organic Biology

Web Resources



  click if a link is broken



Special points of emphasis

Chemical Thermodynamics and the Equilibrium State

Chemical Kinetics

Reactions of Alkenes

Reactions of Conjugated Species

The same electrophiles that undergo electrophilic addition to alkenes, also will add to conjugated dienes, though forming a resonance stabilized allylic cation intermediate. The delocalization of positive charge in the cation intermediate leads to the possibility of two reaction pathways, direct addition (1,2 addition), which produces the Markovnikov adduct, or conjugate addition (1,4 addition).

1,2 addition occurs faster than 1,4 addition (the transition state for anion capture is lower for 1,2 addition), but the 1,4 adduct is more stable (with internal double bond). At lower temperature (kinetic conditions) the 1,2 adduct is the favored product. However, higher temperature (thermodynamic conditions) allows equilibration between the possible products, so the more stable 1,4 adduct is favored.

Kinetic versus thermodynamic control in conjugate addition has been on the MCAT a number of times.








The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

Please read our policies on privacy and shipping & returns.  Contact Us.
MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course.


Creative Commons License
The work of WikiPremed is published under a Creative Commons Attribution Share Alike 3.0 License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions. You can use the resources here for commercial or non-commercial purposes, but please give attribution and a link to the production credits and edit history of the resource. For the works here which began as my individual work, please attribute "John Wetzel, an author at wikipremed.com".