Search results
Results from the WOW.Com Content Network
The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. [1] Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions. Both proceed by electrophilic aromatic substitution. [2] [3] [4] [5]
In Friedel-Crafts alkylations, the normal halogen leaving group order is reversed so that the rate of the reaction follows RF > RCl > RBr > RI. This effect is due to their greater ability to complex the Lewis acid catalyst, and the actual group that leaves is an "ate" complex between the Lewis acid and the departing leaving group. [ 6 ]
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 .
The reaction is a type of Friedel-Crafts acylation with hydrogen chloride and a Lewis acid catalyst. The synthesis of 2,4,6-Trihydroxyacetophenone (THAP) from phloroglucinol is representative: [1] If two-equivalents are added, 2,4-Diacetylphloroglucinol is the product. Hoesch reaction example, 1-(2,4,6-trihydroxyphenyl)ethanone from phloroglucinol
Phenethyl alcohol is prepared commercially via two routes. Most common is the Friedel-Crafts reaction between benzene and ethylene oxide in the presence of aluminium trichloride. C 6 H 6 + CH 2 CH 2 O + AlCl 3 → C 6 H 5 CH 2 CH 2 OAlCl 2 + HCl. The reaction affords the aluminium alkoxide that is subsequently hydrolyzed to the desired product.
The concerted mechanism of this step is similar to the mechanisms of the Baeyer–Villiger oxidation [6] and Criegee rearrangement reactions, and also the oxidation step of the hydroboration–oxidation process. [7] In 2009, an acidified bentonite clay was proven to be a more economical catalyst than sulfuric acid as the acid medium.
James Crafts, the son of Royal Altamont Crafts and Marianne Mason (daughter of Senator Jeremiah Mason), [3] [4] was born in Boston, Massachusetts and graduated from Harvard University in 1858. Although he never received his Ph.D. , he studied chemistry in Germany at the Academy of Mines (1859) of Freiberg , and served as an assistant to Robert ...
The first step is an amide coupling, while the second step is a Friedel–Crafts reaction. [5] [6] An improved procedure has been developed. [7] [8] See also. Indole;