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The Stereochemistry of SN2 Reactions

When the reaction of 2-chlorobutane with hydroxide ion is run in the laboratory, the rate is found to depend on the concentration of both species. This indicates that the re- [Pg.261]

The hydroxide has bonded in the exact position the chlorine originally occupied The product has the same relative stereochemistry as the reactant. The reaction has occurred with retention of configuration. [Pg.261]

The hydroxide has bonded equally to the same side and the opposite side as the original chlorine. A complete loss of stereochemistry has occurred. The reaction has proceeded with racemization. [Pg.261]

Possible stereochemical outcomes for the reaction of (S)-2-chlorobutane with hydroxide ion. Only possibility 2 actually occurs. [Pg.261]

These workers studied the exchange reaction of optically active j-octyl iodide with radioactive iodide ion in acetone (Equation 4.8) and found that (1) the kinetics are second-order, first-order each in octyl iodide and in iodide ion, [Pg.174]

This one-to-one correlation of inversion with displacement must mean that the incoming iodide enters the molecule from the side of the substitution site opposite to the departing iodide every single time. It initially attacks the back lobe of the sp3 orbital used for bonding with the iodide. The transition state proposed by Hughes and co-workers is shown in 1. Carbon has rehybridized and is [Pg.174]

9 For a comprehensive summary of this work see Ingold, Structure and Mechanism in Organic Chemistry, pp. 509ff. [Pg.174]

Inversion of configuration in the displacement of iodide by radioactive iodide and in all reactions of charge type 1 might be explained on the grounds that the bipyramidal transition state shown in 1 allows the entering and leaving [Pg.175]

There is now a great deal of evidence that all SN2 reactions of all charge types proceed with inversion.13 [Pg.176]


Thomson I. Click Organic Process to view an animation showing the stereochemistry of the Sn2 reaction. [Pg.362]

Stereochemistry of the Sn2 reaction A nucleophile donates its electron pairs to the C—X bond on the backside of the leaving group, since the leaving group itself blocks attack from any other direction. Inversion of stereochemistry is observed in the product of an Sn2 reaction. The reaction is stereospecific since a certain stereoisomer reacts to give one specific stereoisomer as product. [Pg.238]

Stork, G. Kreft, A. F. Concerning the stereochemistry of the Sn2 reaction in cyclohexenyl... [Pg.133]

The tosylate leaving group was used in one of the classic experiments that was used to determine the stereochemistry of the SN2 reaction. Now that we know about this leaving group, let s look at the experiment and see how it helped establish that SN2 reactions occur with inversion of configuration. [Pg.282]

Designing an experiment to demonstrate that an SN2 reaction occurs with inversion of configuration is not as simple as it might appear at first glance. For example, consider using the reaction of 2-chlorobutane with hydroxide ion to produce 2-butanol to determine the stereochemistry of the SN2 reaction ... [Pg.282]

Most secondary compounds, such as 11 and 12, will undergo the SN2 reaction (in which the substituents are alkyl groups). When at least one of the groups is aromatic there is some tendency for the group X, the leaving group, to leave of its own accord (this is the basis of the SN1 reaction, Section 7.1.3) rather than to be expelled by the nucleophile in a concerted SN2 reaction. However, the experiments that defined the stereochemistry of the Sn2 reaction were performed on secondary substrates. [Pg.128]

The stereochemistry of the SN2 reaction has been shown to be variously syn (the nucleophile and leaving group are on the same face of the ally lie system) or anti, depending on the nature of the nucleophile and leaving group. For example, the cis isomer 26 with piperidine gave 27, in a clean syn allylic displacement, whereas Na+-SPr gave a ca. 2 1 mixture of isomers in which the trans isomer 28 was the major product. This trend toward anti substitution with RS- is more pronounced (almost exclusive) in the acyclic case 29. [Pg.132]

PROBLEM 12.66 Now here s a much harder problem. The stereochemistry of the Sn2 reaction has been well worked out and has been described in detail in Section 7.4b. The Sn2 reaction has also been investigated, and this problem asks you to put yourself in the place of R. M. Magid (b. 1938) and his co-workers. They used the following experiment to determine the stereochemistry of the Sn2 reaction. Use their data to determine whether the nucleophile approaches the double bond from the same side as the leaving group or from the opposite side. [Pg.569]


See other pages where The Stereochemistry of SN2 Reactions is mentioned: [Pg.128]    [Pg.174]    [Pg.261]    [Pg.261]    [Pg.263]    [Pg.488]    [Pg.610]    [Pg.488]    [Pg.126]    [Pg.239]    [Pg.268]    [Pg.245]    [Pg.247]    [Pg.222]    [Pg.209]   


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