How do you name aromatic compounds with multiple substituents?
How do you name aromatic compounds with multiple substituents?
For benzene rings with multiple substituents, the ring atoms are numbered to minimize the numbering of the substituents groups; alternatively, ortho/meta/para nomenclature can be used for disubstituted rings.
What are aromatic substitution reactions?
Electrophilic aromatic substitution reactions are organic reactions wherein an electrophile replaces an atom which is attached to an aromatic ring. Commonly, these reactions involve the replacement of a hydrogen atom belonging to a benzene ring with an electrophile.
What is benzene and its derivatives?
As it is now used, the term aromatic refers instead to the fact that benzene and its derivatives are highly unsaturated compounds that are unexpectedly stable toward reagents that react with alkenes. We use the term arene to describe aromatic hydrocarbons, by analogy with alkane and alkene. Benzene is the parent arene.
Why is Benzyne electrophilic?
Bonding in o-arynes Geometric constraints on the triple bond in ortho-benzyne result in diminished overlap of in-plane p-orbitals, and thus weaker triple bond. Hence, benzyne possesses electrophilic character and undergoes reactions with nucleophiles.
Which is the most common way to alkylate an aromatic ring?
One of the most common ways to alkylate an aromatic ring is to use an alkyl chloride electrophile that is activated by the addition of aluminum or iron trichloride. The metal chloride serves as a Lewis acid, accepting electron density from the alkyl chloride.
Why are substituents important in electrophilic aromatic substitution?
Because benzene acts as a nucleophile in electrophilic aromatic substitution, substituents that make the benzene more electron-rich can accelerate the reaction. Substituents that make the benzene moor electron-poor can retard the reaction.
What kind of catalyst is used for alkylation?
Friedel–Crafts alkylation involves the alkylation of an aromatic ring with an alkyl halide using a strong Lewis acid catalyst. With anhydrous ferric chloride as a catalyst, the alkyl group attaches at the former site of the chloride ion. The general mechanism is shown below.
When does substitution occur on an aromatic ring?
When substitution does occur on an aromatic ring with deactivating group already attached, it tends to occur specifically at the meta position – deactivating groups are generally meta-directing . The exception to this rule is the halogens, which are ring-deactivating but ortho-para directing (see next section).