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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.
The stabilities of the carbocations formed by this dissociation are known to follow the trend tertiary > secondary > primary > methyl. Therefore, since the tertiary carbocation is relatively stable and therefore close in energy to the R-X reactant, then the tertiary transition state will have a structure that is fairly similar to the R-X reactant.
Adding the hydrogen ion to one carbon atom in the alkene creates a positive charge on the other carbon, forming a carbocation intermediate. The more substituted the carbocation, the more stable it is, due to induction and hyperconjugation. The major product of the addition reaction will be the one formed from the more stable intermediate.
Water leaves the protonated t-BuOH, forming a relatively stable tertiary carbocation. The chloride ion attacks the carbocation, forming t -BuCl. The overall reaction, therefore, is:
Carbocations were also found to be involved in the S N 1 reaction, the E1 reaction, and in rearrangement reactions such as the Whitmore 1,2 shift. The chemical establishment was reluctant to accept the notion of a carbocation and for a long time the Journal of the American Chemical Society refused articles that mentioned them.
The driving force for the actual migration of a substituent in step two of the rearrangement is the formation of a more stable intermediate. For instance a tertiary carbocation is more stable than a secondary carbocation and therefore the S N 1 reaction of neopentyl bromide with ethanol yields tert-pentyl ethyl ether.
Magic acid (FSO 3 H·SbF 5) is a superacid consisting of a mixture, most commonly in a 1:1 molar ratio, of fluorosulfuric acid (HSO 3 F) and antimony pentafluoride (SbF 5).This conjugate Brønsted–Lewis superacid system was developed in the 1960s by Ronald Gillespie and his team at McMaster University, [1] and has been used by George Olah to stabilise carbocations and hypercoordinated ...
A carbocation may be stabilized by resonance by a carbon–carbon double bond or by the lone pair of a heteroatom adjacent to the ionized carbon. The allyl cation CH 2 =CH−CH + 2 and benzyl cation C 6 H 5 −CH + 2 are more stable than most other carbenium ions due to donation of electron density from π systems to the cationic center. [20]