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The reaction proceeds with a cation intermediate, being different from the above halogen addition. An example is shown below: Proton (H +) adds (by working as an electrophile) to one of the carbon atoms on the alkene to form cation 1. Chloride ion (Cl −) combines with the cation 1 to form the adducts 2 and 3.
In organic chemistry, an azo coupling is an reaction between a diazonium compound (R−N≡N +) and another aromatic compound that produces an azo compound (R−N=N−R’).In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the electrophile, and the activated carbon (usually from an arene, which is called coupling agent), serves as a nucleophile.
A typical example of a Lewis acid in action is in the Friedel–Crafts alkylation reaction. [5] The key step is the acceptance by AlCl 3 of a chloride ion lone-pair, forming AlCl − 4 and creating the strongly acidic, that is, electrophilic, carbonium ion. RCl +AlCl 3 → R + + AlCl − 4
By inspection of these structures, it is seen that the positive charge of the mercury atom will sometimes reside on the more substituted carbon (approximately 4% of the time). This forms a temporary tertiary carbocation, which is a very reactive electrophile. The nucleophile will attack the mercuronium ion
This ion is usually obtained as the following salts: ... One example involves anisole: ... Nitronium is a more potent electrophile than is nitrosonium, as anticipated ...
Examples of nucleophiles are anions such as Cl −, or a compound with a lone pair of electrons such as NH 3 and PR 3. [ citation needed ] In the example below, the oxygen of the hydroxide ion donates an electron pair to form a new chemical bond with the carbon at the end of the bromopropane molecule.
For example, para-methoxystyrene is more reactive than styrene itself. Initiation takes place by an initiation/coinitiation binary system, for example an alcohol and a Lewis acid. The active electrophile is then a proton and the counter ion the remaining alkoxide which is stabilized by the Lewis acid.
Sulfur trioxide or its protonated derivative is the actual electrophile in this electrophilic aromatic substitution. To drive the equilibrium, dehydrating agents such as thionyl chloride can be added: [2] C 6 H 6 + H 2 SO 4 + SOCl 2 → C 6 H 5 SO 3 H + SO 2 + 2 HCl. Historically, mercurous sulfate has been used to catalyze the reaction. [3]