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Haloalkane or alkyl halides are the compounds which have the general formula "RX" where R is an alkyl or substituted alkyl group and X is a halogen (F, Cl, Br, I). Haloalkanes have been known for centuries. Chloroethane was produced in the 15th century. The systematic synthesis of such compounds developed in the 19th century in step with the ...
The reaction involves a carbocation intermediate and is commonly seen in reactions of secondary or tertiary alkyl halides under strongly basic conditions or, under strongly acidic conditions, with secondary or tertiary alcohols. With primary and secondary alkyl halides, the alternative S N 2 reaction occurs.
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 alkyl halide. The leaving site must be a primary carbon, because secondary and tertiary leaving sites generally prefer to proceed as an ...
When there are different alkyl groups, they are listed in alphabetical order. In addition, each position on an alkyl chain can be described according to how many other carbon atoms are attached to it. The terms primary, secondary, tertiary, and quaternary refer to a carbon attached to one, two, three, or four other carbons respectively.
For example, reaction of 1-bromooctane with ammonia yields almost equal amounts of the primary amine and the secondary amine. [3] Therefore, for laboratory purposes, N-alkylation is often limited to the synthesis of tertiary amines. An exception is the amination of alpha-halo carboxylic acids that do permit synthesis of primary amines with ...
Methyl and primary substrates react the fastest, followed by secondary substrates. Tertiary substrates do not react via the S N 2 pathway, as the greater steric hindrance between the nucleophile and nearby groups of the substrate will leave the S N 1 reaction to occur first. Substrates with adjacent pi C=C systems can favor both S N 1 and S N 2 ...
Secondary halides are far less reactive. Vinyl , aryl and tertiary alkyl halides are unreactive; as a result, the reaction of NaI in acetone can be used as a qualitative test to determine which of the aforementioned classes an unknown alkyl halide belongs to, with the exception of alkyl iodides, as they yield the same product upon substitution.
The Corey-House synthesis is preceded by two preliminary steps to prepare the requisite Gilman reagent from an alkyl halide. In the first step, the alkyl halide is treated with lithium metal in dry ether to prepare an alkyllithium reagent, RLi. The starting alkyl halide for the lithiation step can be a primary, secondary or tertiary alkyl ...