It is known to transesterify and amidify esters, for example methyl 3-(3,5,di-t-butyl-4-hydroxyphenyl) propionate, with alcohols, such as pentaerythritol, dipentaerythritol, stearyl alcohol, 1,6-hexanediol, 2,2'-thiodiglycol and neopentylglycol, or with amines, such as N-methylamine, N-cyclopropylamine, ethylenediamine and tetramethylenediamine, in the presence of a basic catalyst, such as lithium amide, sodium t-butoxide, potassium hydroxide, and sodium N-methyl-N-phenylamide, in the presence of solvent, such as tetralin or toluene, to form the ester or amide of the alcohol or amine, respectively, employed and methanol as the by-product.
For example, U.S. Pat. No. 4,288,297 describes the transesterification of the above propionate in an inert solvent, such as tetralin, which is used to assist in the removal of the methanol by-product of the reaction. However, the yield from this process is low, and it can lead to peroxide formation, and, in some cases, to undissolved alcohol or amine. U.S. Pat. No. 4,547,858 discloses a process of reacting the above propionate with pentaery-thritol in the presence of a solvent and water, whereby the solvent is distilled off prior to the neutralization of the reaction mixture.
In another process disclosed in U.S. Pat. No. 4,618,700, a 15-50 mol % excess of the propionate is used in place of the inert solvent to assist in the removal of the methanol. While the yield with this process is good, the reaction temperature and pressure are quite severe, e.g. 200.degree. C. at 7 mbar.
To obtain high conversion yield, it is necessary to run such reactions at higher temperatures, i.e. about 180.degree. C. or more, which results in a product having significant discoloration, or to run such reactions for long reaction times, or both. When lower temperatures and times are used, the conversion is reduced.