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The Williamson ether synthesis is an organic reaction, forming an ether from an organohalide and a deprotonated alcohol . This reaction was developed by Alexander Williamson in 1850. [2] Typically it involves the reaction of an alkoxide ion with a primary alkyl halide via an S N 2 reaction.
Darzens halogenation is the chemical synthesis of alkyl halides from alcohols via the treatment upon reflux of a large excess of thionyl chloride or thionyl bromide (SOX 2) in the presence of a small amount of a nitrogen base, such as a tertiary amine or pyridine or its corresponding hydrochloride or hydrobromide salt.
The first step is the ionization of alkyl halide in the presence of aqueous acetone or ethyl alcohol. This step provides a carbocation as an intermediate. In the first step of S N 1 mechanism, a carbocation is formed which is planar and hence attack of nucleophile (second step) may occur from either side to give a racemic product, but actually ...
Deprotonation of the alcohol, forming chloroform, yields an alkoxide 5. The nucleophilic displacement of the chloride by the alkoxide yields intermediate 7. With primary and secondary alcohols, the halide reacts in a S N 2 process forming the alkyl halide 8 and triphenylphosphine oxide. Tertiary alcohols form the products 6 and 7 via a S N 1 ...
The general mechanism for primary alkyl halides is shown below. [8] Mechanism of Friedel–Crafts alkylation. For primary (and possibly secondary) alkyl halides, a carbocation-like complex with the Lewis acid, [R (+)---(X---MX n) (–)] is more likely to be involved, rather than a free carbocation.
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
The Barbier reaction is an organometallic reaction between an alkyl halide (chloride, bromide, iodide), a carbonyl group and a metal. The reaction can be performed using magnesium, aluminium, zinc, indium, tin, samarium, barium or their salts. The reaction product is a primary, secondary or tertiary alcohol.
Amine alkylation (amino-dehalogenation) is a type of organic reaction between an alkyl halide and ammonia or an amine. [1] The reaction is called nucleophilic aliphatic substitution (of the halide), and the reaction product is a higher substituted amine. The method is widely used in the laboratory, but less so industrially, where alcohols are ...