What are endo and exo products?
In the exo product, the pair of hydrogens on the diene ends up cis to the pair of hydrogens on the dienophile when the rings become fused. In the endo product, the opposite is true: the pair of hydrogens on the diene come out trans to the pair of hydrogens on the dienophile when the rings fuse together.
How do you know if Diels-Alder is endo or exo?
6. How Do You Know If A Diels-Alder Will Give You Endo And Exo Products?
- If all of the “outside” groups on the diene are the same as the “inside” groups, then there can’t be exo or endo.
- If the dienophile lacks a substituent that can be distinguished as the “electron withdrawing group”, then there won’t be exo or endo.
What is endo and exo conformation?
endo–exo isomerism is a special type of stereoisomerism found in organic compounds with a substituent on a bridged ring system. The prefix endo is reserved for the isomer with the substituent located closest, or “syn”, to the longest bridge.
Which is more stable endo or exo?
The exo product, on the other hand, is more stable as the substituent of the dienophile is pointing away from the larger ring system. Therefore, it is the thermodynamic product (more stable) and the endo is the kinetic product (forms faster).
What is endo and exo stereochemistry?
Now we’ll need to draw in the stereochemistry. The ENDO product is the one where the “outside” groups on the diene are on the SAME side of the 6-membered ring as the electron withdrawing group (EWG). The EXO product is the one where the “outside” groups are on the OPPOSITE side of the ring as the 6-membered ring.
Why is exo more stable?
The exo product is most stable as the smaller one-atom bridge eclipses the anhydride ring causing less steric hindrance, and is the thermodynamic product. Under reversible conditions, the exo product is formed.
What is the difference between Endo and exothermic reactions?
An exothermic process releases heat, causing the temperature of the immediate surroundings to rise. An endothermic process absorbs heat and cools the surroundings.”
Why is Endo preferred over exo Diels-Alder?
The preference for endo versus exo is especially curious since the endo products appear to be more sterically hindered. Note that in the endo product above, the anhydride is on the underside of the new six-membered ring, whereas in the exo, it points away. This is indeed less sterically hindered.
What are exo and endothermic reactions?
Exothermic reactions transfer energy to the surroundings and the temperature of the surroundings increases. Endothermic reactions take in energy and the temperature of the surroundings decreases.
Why is Endo preferred?
The endo product is kinetically favored, which means that under conditions of low temperature and limited time, it will be the major product that is formed. This is because the transition state of the formation of the endo product is lower in energy due to overlap of secondary orbitals.
Why are exo products more stable?
Why is Endo favored over exo?
This is because the transition state of the formation of the endo product is lower in energy due to overlap of secondary orbitals. However, the exo product is more stable and lower in energy and therefore thermodynamically favored.