What is bridgehead in chemistry?

What is bridgehead in chemistry?

Bridgehead: An atom that is part of two or more rings in a polycyclic molecule. Bridgehead carbons in naphthalene. All eight carbons of cubane are bridgehead atoms.

What is bridge head position?

A bridged bicycloalkane is a bicycloalkane whose molecule has two carbon atoms shared by all three rings identifiable in the molecule. The two carbon atoms shared by the three rings are called bridgehead carbon atoms. A bond or a chain of bonds connecting the bridgehead carbon atoms is called a bridge.

What is hybridization of bridgehead carbon?

The normal geometry for a sp2 hybridized carbon is trigonal planar. However, due to the constraints placed on it by being part of multiple rings, the bridgehead carbon becomes “pyramidalized”, that is to say, somewhat like a pyramid (non-planar). In other words it has a very atypical shape for an sp2 hybridized carbon.

Are bicyclic compounds more stable?

Bicyclic compounds that have bridgehead double bonds within larger rings are more stable and can be isolated. the greater heat of formation.

Why does Bredt’s rule occur?

Bredt’s rule is a consequence of the fact that having a double bond on a bridgehead would be equivalent to having a trans double bond on a ring, which is not stable for small rings (fewer than eight atoms) due to a combination of ring strain, and angle strain (nonplanar alkene).

How do you identify bridgehead carbon?

A bridgehead carbon atom is a carbon atom which is shared by at least two rings. The hydrogen atom which is attached to a bridgehead carbon may be referred to as a bridgehead hydrogen.

What is bridgehead in military?

bridgehead. / (ˈbrɪdʒˌhɛd) / noun military. an area of ground secured or to be taken on the enemy’s side of an obstacle, esp a defended river. a fortified or defensive position at the end of a bridge nearest to the enemy.

Is bridgehead free radical stable?

Our results show this bridgehead free radical to be signifi- cantly less stable (the difference in rate of forma- tion is a factor of ten), and, because the radicals are formed directly and no assumptions must be made on two different competing reactions, the perester decompositions are probably better measures of …

What is Hofmann’s rule?

Hofmann’s rule: When an elimination reaction which can produce two or more alkene (or alkyne) products, the product containing the less highly substituted pi bond is major.

What is Antiperiplanar in organic chemistry?

In organic chemistry, anti-periplanar, or antiperiplanar, describes the A–B–C–D bond angle in a molecule. In a Newman projection, the molecule will be in a staggered arrangement with the anti-periplanar functional groups pointing up and down, 180° away from each other (see Figure 4).

What is bridgehead hydrogen?

What is Bredt’s rule (1924)?

This post is all about Bredt’s Rule (1924): double bonds cannot be placed at the bridgehead of a bridged ring system.

What is the Bredt rule in chemistry?

The rule is named after Julius Bredt, who first discussed it in 1902 and codified it in 1924. It primarily relates to bridgeheads with carbon-carbon and carbon-nitrogen double bonds.

Why does Bredt’s rule not apply to the small rings?

The constraint dictated by Bredt’s Rule has now been attributed to the fact that the small and common rings can accommodate only a cis- double bond. A bridgehead olefin demands a trans- geometry at the olefin.

What is an example of Bredt’s rule violation?

For example, two of the following isomers of norbornene violate Bredt’s rule, which makes them too unstable to prepare: In the figure, the bridgehead atoms involved in Bredt’s rule violation are highlighted in red.