2.4- Dimethylphenol, Mannich reaction

The rate of the reaction of 2,4-dimethylphenol with formaldehyde and morpholine depends on the concentration of morpholine if it is present at less than twice the formaldehyde concentration, but if the formaldehyde concentration is less than half that of morpholine then the rate depends on the concentration of formaldehyde. These data suggest that di- -morpholinylmethane is an intermediate in the reaction. Di- -morpholinylmethane was shown to give essentially the same kinetics.A kinetic study of the reaction of 3-pentadecylphenol with formaldehyde and di-n-propylamine led to a similar conclusion." These results suggest that aminals and aminol ethers should take part in Mannich reactions since both can be formed reversibly in the aqueous or alcoholic media used under the more traditional reaction conditions. 

The technical syntheses are based on the condensation of phytol or isophytol with trimethylhydroquinone, which can be prepared from 3,5-dimethylphenol by the Mannich reaction followed by a series of obvious steps. We prepared radioactive C -labelcd trimethylhydroquinone (specific activity 11.8 ic/mg), os shown in Fig. 2. 

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