Vilsmeier–Haack reaction
Template:Short description Template:Use dmy dates Template:Reactionbox The Vilsmeier–Haack reaction (also called the Vilsmeier reaction) is the chemical reaction of a substituted formamide (1) with phosphorus oxychloride and an electron-rich arene (3) to produce an aryl aldehyde or ketone (5):
- Template:Awrap HArZ + POCl3 + H2O → RC(=O)ArZ + Template:Awrap HCl + H3PO4
The reaction is named after Anton Vilsmeier and Template:Interlanguage link.[1][2][3]
For example, benzanilide and dimethylaniline react with phosphorus oxychloride to produce an unsymmetrical diaryl ketone.[4] Similarly, anthracene is formylated at the 9-position.[5] The reaction of anthracene with N-methylformanilide, also using phosphorus oxychloride, gives 9-anthracenecarboxaldehyde:
File:Vilsmeier reaction example2.svg N-Methylformanilide and anthracene and phosphorus oxychloride
In general, the electron-rich arene (3) must be much more active than benzene for the reaction to proceed; phenols or anilines are good substrates.[6]
Reaction mechanism
The reaction of a substituted amide with phosphorus oxychloride gives a substituted chloroiminium ion (2), also called the Vilsmeier reagent. The initial product is an iminium ion (4b), which is hydrolyzed to the corresponding ketone or aldehyde during workup.[7]
File:Vilsmeier Haack Reaction Scheme.png The Vilsmeier–Haack reaction
See also
Further reading
- Script error: No such module "Citation/CS1".
- Script error: No such module "Citation/CS1".
- A widely-recommended procedure: Script error: No such module "doi".
References
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Template:OrgSynth
- ↑ Template:OrgSynth
- ↑ Template:OrgSynth
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".