Carbocation trigonal planar

To illustrate the consequences of having a trigonal planar carbocation formed as a reactive intermediate, we examine the SnI reaction of a 3° alkyl halide A having the leaving group bonded to a stereogenic carbon. [Pg.255]

Br is the leaving group and H2O is the nucleophile. Loss of the leaving group generates a trigonal planar carbocation, which can react with the nucleophile from either direction to form two products. [Pg.256]

The two products in this reaction are nonsuperimposable mirror images—enantiomers. Because nucleophilic attack on the trigonal planar carbocation occurs with equal frequency from both directions, a racemic mixture is formed. [Pg.257]

A trigonal planar carbocation reacts with nucleophiles from both sides of the plane. [Pg.273]

Trigonal planar carbocation intermediate (8.6B) Favored by weak bases (8.6C)... [Pg.307]

The 3° alcohol C reacts with HCl via an SnI mechanism to yield a racemic mixture of alkyl chlorides D and E, because a trigonal planar carbocation intermediate is formed. [Pg.337]

Nucleophilic attack of Cl on the trigonal planar carbocation also occurs from two different directions, forming two products, A and B, having a new stereogenic center. A and B are not... [Pg.378]

Answer The SnI route first loses the leaving group through path Dn to form a trigonal planar carbocation that is trapped from either side by path An-... [Pg.104]

Figure 20.77 The formation of a trigonal planar carbocation intermediate from an optically active halogenoalkane... [Pg.712]

Trigonal planar carbocation intermediate Racemization at a single stereogenic center... [Pg.256]

Stereochemistry Backside attack of the nucleophile (7.110) Trigonal planar carbocation intermediate (7.130)... [Pg.270]

Stereochemistry backside attack of the trigonal planar carbocation... [Pg.159]

Addition of H (from HBr) from above and below gives an achiral, trigonal planar carbocation. [Pg.265]

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