Tert-Butyl cation 2-methylpropene

We can extend the general principles of electrophilic addition to acid catalyzed hydration In the first step of the mechanism shown m Figure 6 9 proton transfer to 2 methylpropene forms tert butyl cation This is followed m step 2 by reaction of the car bocation with a molecule of water acting as a nucleophile The aUcyloxomum ion formed m this step is simply the conjugate acid of tert butyl alcohol Deprotonation of the alkyl oxonium ion m step 3 yields the alcohol and regenerates the acid catalyst... 

The two dimers of (CH3)2C=CH2 are formed by the mechanism shown m Figure 6 16 In step 1 protonation of the double bond generates a small amount of tert butyl cation m equilibrium with the alkene The carbocation is an electrophile and attacks a second molecule of 2 methylpropene m step 2 forming a new carbon-carbon bond and generating a carbocation This new carbocation loses a proton m step 3 to form a mixture of 2 4 4 tnmethyl 1 pentene and 2 4 4 tnmethyl 2 pentene... 

The tert butyl group is cleaved as the corresponding carbocation Loss of a proton from tert butyl cation converts it to 2 methylpropene Because of the ease with which a tert butyl group is cleaved as a carbocation other acidic reagents such as trifluoroacetic acid may also be used... 

Protonation of 2-methylpropene gives the tert-butyl cation, which carries out an electrophilic aromatic substitution reaction. 

Attack by the tert-butyl cation on another molecule of 2-methylpropene produces an eight-carbon tertiary cation, which then proceeds to another molecule of alkylate ... 

In the presence of an acid catalyst (H2S04), 2-methylpropene is converted to tert-butyl cation, which then attacks the aromatic ring ortho to the strongly activating methoxy group. ... 

Reaction coordinate diagram for the addition of to 2-methylpropene to form the primary isobutyl cation and the tertiary tert-butyl cation. 

Methylpropene tert-Butyl cation 1,1,3,3-Tetramethylbutyl cation... 

Treatment of 2-methylpropene with hot aqueous sulfuric acid gives two dimers 2,4,4-trimethyl-1-pentene and 2,4,4,-trimethyl-2-pentene. This transformation is possible because 2-methylpropene can be protonated undOT the reaction conditions to furnish the 1,1-dimethylethyl (tert-butyl) cation. This species can attack the electron-rich double bond of 2-methylpropene with formation of a new carbon-carbon bond. Electrophihc addition proceeds according to the Markovnikov rule to generate the more stable carbocalion. Subsequent deprotonation from either of two adjacent carbons furnishes a mixture of the two observed products. 

A new class of polymetallic organolanthanide polyhydride complexes was found by W.J. Evans et al. (1982b). Dicyclopentadienyl-tert-butyl erbium tetrahydrofur-anate decomposes in toluene in the presence of Uthium chloride within ten hours at room temperature with formation of 2-methylpropane, 2-methylpropene and a pink compound, which shows a broad absorption in the infrared spectrum between 1250 and 1200 cm for the j (ErH). A single crystal X-ray structural determination of a pink prismatic crystal shows cation-anion pairs with three dicyclopentadienyl... 

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