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- Bredt's_rule abstract "Bredt's rule is an empirical observation in organic chemistry that states that a double bond cannot be placed at the bridgehead of a bridged ring system, unless the rings are large enough. The rule is named after Julius Bredt.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.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 possible for small rings (fewer than eight atoms) due to a combination of ring strain, and angle strain (nonplanar alkene). The p orbitals of the bridgehead atom and adjacent atoms are orthogonal and thus are not aligned properly for the formation of pi bonds.Bredt's rule can be useful for predicting which isomer is obtained from an elimination reaction in a bridged ring system. It can also be applied to reaction mechanisms that go via carbocations and, to a lesser degree, via free radicals, because these intermediates, like carbon atoms involved in a double bond, prefer to have a planar geometry with 120 degree angles and sp2 hybridization.An anti-bredt molecule is one that is found to exist and be stable (within certain parameters) despite this rule. A recent (2006) example such a molecule is 2-quinuclidonium tetrafluoroborate.".
- Bredt's_rule thumbnail Norbornene_isomers_Bredt_rule.png?width=300.
- Bredt's_rule wikiPageID "3176865".
- Bredt's_rule wikiPageRevisionID "550394962".
- Bredt's_rule hasPhotoCollection Bredt's_rule.
- Bredt's_rule subject Category:Physical_organic_chemistry.
- Bredt's_rule subject Category:Stereochemistry.
- Bredt's_rule comment "Bredt's rule is an empirical observation in organic chemistry that states that a double bond cannot be placed at the bridgehead of a bridged ring system, unless the rings are large enough.".
- Bredt's_rule label "Bredt's rule".
- Bredt's_rule label "Bredtsche Regel".
- Bredt's_rule label "Regel van Bredt".
- Bredt's_rule label "Regla de Bredt".
- Bredt's_rule label "Правило Бредта".
- Bredt's_rule label "ブレット則".
- Bredt's_rule label "布莱特规则".
- Bredt's_rule sameAs Bredtsche_Regel.
- Bredt's_rule sameAs Regla_de_Bredt.
- Bredt's_rule sameAs ブレット則.
- Bredt's_rule sameAs Regel_van_Bredt.
- Bredt's_rule sameAs m.08x95v.
- Bredt's_rule sameAs Q900838.
- Bredt's_rule sameAs Q900838.
- Bredt's_rule wasDerivedFrom Bredt's_rule?oldid=550394962.
- Bredt's_rule depiction Norbornene_isomers_Bredt_rule.png.
- Bredt's_rule isPrimaryTopicOf Bredt's_rule.