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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 ...
In this method, the sodium or potassium salt of phthalimide is N-alkylated with a primary alkyl halide to give the corresponding N-alkylphthalimide. [8] [9] [10] Upon workup by acidic hydrolysis the primary amine is liberated as the amine salt. [11] Alternatively the workup may be via the Ing–Manske procedure, involving reaction with hydrazine.
For example, 1-bromo-1-fluoroethane can undergo nucleophilic attack to form 1-fluoroethan-1-ol, with the nucleophile being an HO − group. In this case, if the reactant is levorotatory, then the product would be dextrorotatory, and vice versa. [3] S N 2 mechanism of 1-bromo-1-fluoroethane with one of the carbon atoms being a chiral centre.
Likewise, this method only gives the best yields for primary halides. Secondary and tertiary halides are prone to undergo E2 elimination on exposure to the basic alkoxide anion used in the reaction due to steric hindrance from the large alkyl groups. In a related reaction, alkyl halides undergo nucleophilic displacement by phenoxides. The R–X ...
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 ...
Here, a strong Lewis acid is required to generate either a carbocation from an alkyl halide in the Friedel-Crafts alkylation reaction or an acylium ion from an acyl halide. In the vast majority of cases, reactions that involve leaving group activation generate a cation in a separate step, before either nucleophilic attack or elimination.
Phosphite esters with tertiary alkyl halide groups can undergo the reaction, which would be unexpected if only an S N 2 mechanism was operating. Further support for this S N 1 type mechanism comes from the use of the Arbuzov reaction in the synthesis of neopentyl halides, a class of compounds that are notoriously unreactive towards S N 2 reactions.
Traditionally, the alkylating agents are alkyl halides. Many alkylating agents can be used instead of alkyl halides. For example, enones and epoxides can be used in presence of protons. The reaction typically employs a strong Lewis acid, such as aluminium chloride as catalyst, to increase the electrophilicity of the alkylating agent. [6]