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The IUPAC acknowledges the three divergent definitions of carbonium ion and urges care in the usage of this term. For the remainder of this article, the term carbonium ion will be used in this latter restricted sense, while non-classical carbocation will be used to refer to any carbocation with C–C and/or C–H σ-bonds delocalized by bridging.
The structure is described as R−C≡O + or R− + =O. It is an acyl carbocation, but the actual structure has the oxygen and carbon linked by a triple bond. Such species are common reactive intermediates, for example, in the Friedel−Crafts acylations also in many other organic reactions such as the Hayashi rearrangement.
A tertiary carbon atom is a carbon atom bound to three other carbon atoms. [1] For this reason, tertiary carbon atoms are found only in hydrocarbons containing at least four carbon atoms. They are called saturated hydrocarbons because they only contain carbon-carbon single bonds. [2] Tertiary carbons have a hybridization of sp3.
Structure of the 2-norbornyl cation based on X-ray crystallography. All other C-C bond lengths are normal (ca. 1.5 Å). [1] In chemistry, a carbonium ion is a cation that has a pentacoordinated carbon atom. [2] They are a type of carbocation. In older literature, the name "carbonium ion" was used for what is today called carbenium.
The migration of alkyl groups in this reaction occurs in accordance with their usual migratory aptitude, i.e.phenyl carbocation > hydride > tertiary carbocation (if formed by migration) > secondary carbocation (if formed by migration) > methyl carbocation. {Why carbocation? Because every migratory group leaves by taking electron pair with it.}
Using Hammond's postulate, the lower energy of the tertiary transition state means that its structure is relatively closer to its reactants R(tertiary)-X than to the carbocation product when compared to the secondary case. Thus, the tertiary transition state will be more geometrically similar to the R(tertiary)-X reactants than the secondary ...
A secondary carbon has two carbon neighbors. A tertiary carbon has three carbon neighbors. A quaternary carbon has four carbon neighbors. In "structurally complex organic molecules", it is the three-dimensional orientation of the carbon–carbon bonds at quaternary loci which dictates the shape of the molecule. [3]
Tertiary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermediates (e. g. alkyl radicals, carbocations). Red highlighted central atoms in various groups of chemical compounds.