What is anti and syn?

An addition reaction of an alkene or an alkyne in which the net reaction is addition of two ligands to the multiple-bonded carbon atoms from the same face of the multiple bond is called a syn addition; one in which the net reaction is addition of the two ligands from the opposite faces of the multiple bond is called an …

Is anti addition Stereoselectivity?

Syn and Anti Additions to Alkenes When two groups add to the same side of the double bond, it is called a syn addition and when they add from different sides, it is an anti addition.

How do you know if it’s syn or anti addition?

When both atoms/groups add to the same face it’s considered syn addition. When they add to opposite faces it’s considered anti addition. The difference between the two is determined by which atom the group added to (Mark vs Anti-Mark) or to which SIDE it adds (syn vs anti).

What is SYN Stereoselectivity?

Stereoselectivity. When an alkene undergoes addition, two new s bonds are formed. If we think of an alkene as having two faces, then the two new s bonds can either both form on the same face, which we call syn addition, or they can be formed on different faces which we call anti addition.

Why is halogenation anti?

As a nucleophile, the halogen is attracted to partially positive carbon atoms in the bridged molecule. The resulting product has 2 halogens attached on opposite sides or ‘anti’ to each other. Since carbon can only have 4 bonds, this attack forces carbon to let go of the bridge halogen, thus breaking the bridge.

Does syn mean CIS?

*Note: The term syn is more appropriate for describing a system where a rotation about a single bond is possible, while cis is used mostly for alkenes and cyclic systems which are locked and cannot change the orientation of the groups. However, in this article, the terms syn/cis and anti/trans are used interchangeably.

Is SYN the same as cis?

The difference is subtle: “cis” and “trans” implies that the orientation of the two groups is locked; you can’t convert cis to trans through rotation. The terms “syn” and “anti” imply similar relationships to “cis” and “trans”, but can also be applied to systems which are not locked.

Is halogenation an anti or syn?

In anti addition, two substituents are added to opposite sides (or faces) of a double bond or triple bond, once again resulting in a decrease in bond order and increase in number of substituents. The classical example of this is bromination (any halogenation) of alkenes.

What is Kharasch effect?

Kharasch effect also known as “peroxide effect” and termed as anti-markovnikov’s rule is the effect shown when unsymmetrical alkenes react with alkyl halides (especially HBr) in the presence of peroxides (mostly of benzenes) and the reaction proceeds via a free radical mechanism.