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The Bouveault aldehyde synthesis (also known as the Bouveault reaction) is a one-pot substitution reaction that replaces an alkyl or aryl halide with a formyl group using a N,N-disubstituted formamide. [1] [2] For primary alkyl halides this produces the homologous aldehyde one carbon longer. For aryl halides this produces the corresponding ...
This method produces a precipitate of phthalhydrazide (C 6 H 4 (CO) 2 N 2 H 2) along with the primary amine: C 6 H 4 (CO) 2 NR + N 2 H 4 → C 6 H 4 (CO) 2 N 2 H 2 + RNH 2. Gabriel synthesis generally fails with secondary alkyl halides. The first technique often produces low yields or side products. Separation of phthalhydrazide can be challenging.
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]
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.
However, using an additive such as silver tetrafluoroborate allows the reaction to work on a wider range of substrates, as often seen for alkyl-halide substitutions, or they can be converted first to the corresponding alkyl tosylate. [4] [5] The reaction was initially limited to activated substrates, such as benzylic and α-halo ketones.
It is used to prepare alkyl triflates from alkyl halides: [5] CF 3 SO 2 OAg + RX → CF 3 SO 2 OR + AgX (X = iodide usually) In coordination chemistry, the salt is also useful to replace halide ligands with the more labile triflate ligand. For example, bromopentacarbonylrhenium can be converted to the more labile derivative using silver ...
A positive test is indicated by a change from clear and colourless to turbid, signalling formation of a chloroalkane. [1] Also, the best results for this test are observed in tertiary alcohols, as they form the respective alkyl halides fastest due to higher stability of the intermediate tertiary carbocation.
The Kolbe nitrile synthesis is a method for the preparation of alkyl nitriles by reaction of the corresponding alkyl halide with a metal cyanide. [1] A side product for this reaction is the formation of an isonitrile because the cyanide ion is an ambident nucleophile. The reaction is named after Hermann Kolbe.