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Friedel–Crafts alkylations can be reversible. Although this is usually undesirable it can be exploited; for instance by facilitating transalkylation reactions. [10] 1,3-Diisopropylbenzene is produced via transalkylation, a special form of Friedel–Crafts alkylation. It also allows alkyl chains to be added reversibly as protecting groups.
Asymmetric Friedel–Crafts hydroxyalkylation. In another alkylation N-methylpyrrole reacts with crotonaldehyde catalyzed by trifluoroacetic acid modified with a chiral imidazolidinone: [8] Friedel Crafts Asymmetric Addition To Pyrrole. Indole reacts with an enamide catalyzed by a chiral BINOL derived phosphoric acid: [9]
The Friedel-Crafts alkylation process involves chlorination of n-paraffins to monochloroparaffins followed by alkylation of benzene using aluminum chloride (AlCl 3) catalyst. This method is one of the oldest commercial routes to LABs. Each process generates LAB products with distinct features.
Friedel-Crafts alkylation of benzene is often catalyzed by aluminium trichloride. Electrophilic alkylation uses Lewis acids and Brønsted acids, sometimes both. Classically, Lewis acids, e.g., aluminium trichloride, are employed when the alkyl halide are used. Brønsted acids are used when alkylating with olefins.
Cumene is formed in the gas-phase Friedel–Crafts alkylation of benzene by propene. Benzene and propene are compressed together to a pressure of 30 standard atmospheres at 250 °C in presence of a catalytic Lewis acid. Phosphoric acid is often favored over aluminium halides.
Clemmensen reduction conditions are particularly effective at reducing aryl [4]-alkyl ketones, [5] [6] such as those formed in a Friedel-Crafts acylation. The two-step sequence of Friedel-Crafts acylation followed by Clemmensen reduction constitutes a classical strategy for the primary alkylation of arenes.
In electrophilic substitution in aromatic compounds, an atom appended to the aromatic ring, usually hydrogen, is replaced by an electrophile.The most important reactions of this type that take place are aromatic nitration, aromatic halogenation, aromatic sulfonation and acylation and alkylating Friedel-Crafts reactions.
A native of Strasbourg, France, he was a student of Louis Pasteur at the Sorbonne.In 1876, he became a professor of chemistry and mineralogy at the Sorbonne.. Friedel developed the Friedel-Crafts alkylation and acylation reactions with James Crafts in 1877, [2] [3] and attempted to make synthetic diamonds.