Cresols, nitrosation

Under the same conditions the even more reactive compounds 1,6-dimethylnaphthalene, phenol, and wt-cresol were nitrated very rapidly by an autocatalytic process [nitrous acid being generated in the way already discussed ( 4.3.3)]. However, by adding urea to the solutions the autocatalytic reaction could be suppressed, and 1,6-dimethyl-naphthalene and phenol were found to be nitrated about 700 times faster than benzene. Again, the barrier of the encounter rate of reaction with nitronium ions was broken, and the occurrence of nitration by the special mechanism, via nitrosation, demonstrated. 

The nitrosation of phenol and cresols in buffer solutions involves a diffusion-controlled C-nitrosation followed by rate-limiting proton loss. /r-Crcsol is much less reactive than the other substrates.79 Nitrosation in trifluoroacetic acid or in acetic-sulfuric acid mixtures is regioselective (e.g. 4-nitroso-m-xylene is fonned from m-xylene) and possible non-selective nitrous acid-catalysed nitration can be eliminated by purging reaction solutions with nitric oxide.80... 

Nitrosation, acetonedicarboxylic acid, 96 carbazole, 218 o-cresol, 203 dimethylaniline, 115 ethyl malonate, 153, 156... 

In addition, m-cresol is used to produce plant protection agents such as feni-trothion. The manufacturing process involves nitrosation of m-cresol with nitrous acid esters in isopropanol, and subsequent oxidation of the nitroso compounds with nitric acid to yield 4-nitro m-cresol (or its sodium salt), which, when acted upon by 0,0-dimethyl thiophosphoric acid chloride, gives fenitrothion. 

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