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Many reactions studied are solvolysis reactions where a solvent molecule (often an alcohol) is the nucleophile. While still a second order reaction mechanistically, the reaction is kinetically first order as the concentration of the nucleophile–the solvent molecule, is effectively constant during the reaction.
The determining factor when both S N 2 and S N 1 reaction mechanisms are viable is the strength of the Nucleophile. Nuclephilicity and basicity are linked and the more nucleophilic a molecule becomes the greater said nucleophile's basicity. This increase in basicity causes problems for S N 2 reaction mechanisms when the solvent of choice is protic.
For example, the substituent may determine the mechanism to be an SN1 type reaction over a SN2 type reaction, in which case the resulting Hammett plot will indicate a rate acceleration due to an EDG, thus elucidating the mechanism of the reaction. Another deviation from the regular Hammett equation is explained by the charge of nucleophile.
The two main mechanisms were the S N 1 reaction and the S N 2 reaction, where S stands for substitution, N stands for nucleophilic, and the number represents the kinetic order of the reaction. [4] In the S N 2 reaction, the addition of the nucleophile and the elimination of leaving group take place simultaneously (i.e. a concerted reaction).
An example of a solvolysis reaction is the reaction of a triglyceride with a simple alcohol such as methanol or ethanol to give the methyl or ethyl esters of the fatty acid, as well as glycerol. This reaction is more commonly known as a transesterification reaction due to the exchange of the alcohol fragments.
In order for the S N 2 reaction to take place there must be a good leaving group which is strongly electronegative, commonly a halide. [4] In the Williamson ether reaction there is an alkoxide ion (RO −) which acts as the nucleophile, attacking the electrophilic carbon with the leaving group, which in most cases is an alkyl tosylate or an ...
In many substitution reactions, well-defined intermediates are not observed, when the rate of such processes are influenced by the nature of the entering ligand, the pathway is called associative interchange, abbreviated I a. [3] Representative is the interchange of bulk and coordinated water in [V(H 2 O) 6] 2+.
The classic Finkelstein reaction entails the conversion of an alkyl chloride or an alkyl bromide to an alkyl iodide by treatment with a solution of sodium iodide in acetone. Sodium iodide is soluble in acetone while sodium chloride and sodium bromide are not; [ 3 ] therefore, the reaction is driven toward products by mass action due to the ...