Mannich reactions have been carried out with a variety of model alkylphenols and dimethylamine, methylamine, and diethylenetriamine to trace the origin of persistent coloured products occurring in related reactions with pentadeca (e) nylphenol and 4-tert- alkylphenols. It was found to be attributable to the presence of resorcinolic impurities.
![Phenol,2,6-bis[(dimethylamino)methyl]-4-(1,1-dimethylethyl)-结构式](https://image.chemsrc.com/caspic/117/5414-79-9.png)