Therefore, weak bases can beused. Base-promoted halogenation of methyl ketones is difficult tostop the reaction at the monosubstituted product. ed. The haloform reaction convertsmethyl ketones into a carboxylic acid and a haloform and is used as a qualitativetest for methyl ketones.
Nucleophilic substitution reactions can be useful in organic synthesis. Mostly they are used for the interconversion of functional groups. For example, an alkyl halide might be transformed into an alcohol, or into an ether.
the Williamson ether synthesis, ..
This page gives you the facts and simple, uncluttered mechanisms for the nucleophilic substitution reactions between halogenoalkanes and hydroxide ions (from, for example, sodium hydroxide). If you want the mechanisms explained to you in detail, there is a link at the bottom of the page.
Mechanism of Nucleophilic Substitution
We can't take the same approach in ether synthesis. An ether is an oxygen bridge between two tetrahedral or sp3 carbons; we can't have resonance stabilisation and still have those two sp3 carbons. Instead, another strategy is sometimes employed during addition of an anionic nucleophile to an alkyl halide. An alkoxide ion is still employed, but care is taken in how the alkoxide and the alkyl halide are chosen. Because the ether is symmetric -- it is two tetrahedral carbons attached to an oxygen -- either side could originate as the alkoxide and either side could originate as the alkyl halide.
Substitution Reaction of an Ether with a Stable Carbocation ..
In general, the use of alkoxide ions as nucleophiles can be pretty successful if done carefully, and this approach to making ethers even has its own name. It's called the Williamson ether synthesis.