What is suprafacial and antarafacial?

The key difference between suprafacial and antarafacial is that the term suprafacial refers to the relationship between two simultaneous chemical bonds making and/or breaking processes in the same face of a pi system or in an isolated orbital, whereas the term antarafacial refers to the same relationship in opposite …

What is antarafacial?

Antarafacial: A sigmatropic reaction or mechanism step in which the sigma bond changes occur on opposite faces of the molecule. This antarafacial 1,3-H shift is thermally allowed by the Woodward-Hoffmann rules, but prevented by excessive strain in the transition state.

What is suprafacial and antarafacial shift of hydrogen?

Suprafacial and antarafacial shifts If the migrating group remains on the same face of the π system, the shift is known as suprafacial, while if the migrating group transfers to the opposite face is called an antarafacial shift, which are impossible for transformations that occur within small- or medium-sized rings.

What is suprafacial process?

Suprafacial: A sigmatropic reaction or mechanism step in which the sigma bond changes occur on the same face of the molecule.

What is suprafacial cycloaddition?

Cycloaddition reactions and sigmatropic rearrangements both involve pairs of σ-bond-making events (or a coupled bond-making & bond-breaking) associated with a π-electron system. If all the bonding events take place on the same face of the π-system the configuration of the reaction is termed suprafacial.

What is Conrotatory motion?

In conrotatory mode, both atomic orbitals of the end groups turn in the same direction (such as both atomic orbitals rotating clockwise or counter-clockwise). In disrotatory mode, the atomic orbitals of the end groups turn in opposite directions (one atomic orbital turns clockwise and the other counter-clockwise).

What is meant by suprafacial mode of cycloaddition?

Suprafacial means that the new sigma bonds are formed on the same face of each reactant, the diene and the dienophile. The opposite of suprafacial is antarafacial. The term [4+2] refers to a 4-electron conjugated system reacting with a 2-electron system.

What is Conrotation?

A conrotation means that the orbitals will rotate in the same direction (either clockwise or counterclockwise). A disrotation, which is the other method by which the orbitals can form a bond, is a rotation in which the two orbitals will rotate in opposite directions.

What is conrotatory process?

What does the word pericyclic mean?

Relating to or denoting a reaction that involves a concerted rearrangement of bonding in which all the bonds broken or formed in the reaction lie on a closed ring, whether or not a cyclic molecule is involved. ‘In pericyclic reactions, bonds are made or broken in a concerted cyclic transition state. ‘

How do you determine conrotatory and disrotatory?

The change in orbital symmetry leads to a change in how the end carbons must rotate to form a new sigma bond, which can be either “conrotatory” (both ends rotate in the same direction) or “disrotatory” (both ends rotate in opposite directions), as we’ll see below.