アクリル酸2-エチルヘキシルの研究(その2)

抄録

2-Ethylhexyl acrylate was synthesized through direct esterification of acrylic acid (1) with 2-ethylhexyl alcohol (2), and through ester-interchange reaction between methyl acrylate (3) and (2).
The high-boiling by-products were found to be 2-ethylhexyl β-(2-ethylhexyloxy)propionate (4) in the former case ; and (4), methyl β-(2-ethylhexyloxy)propionate (5), 2-ethylhexyl methoxypropionate (6), and methyl β-methoxy. propionate (7) in the latter case. Apparent activation energies were calculated to be 18.1 kcal/mol for the esterification and 13.9 kcal/mol for the ester-interchange. On the other hand, the values for the formations of (4), (5) and (6) were about 27.1, 13.4 and 14.3 kcal/mol, respectively. The activation energy for (7) formation could not be measured due to its extremely low reaction velocity.
In the synthesis of 2-ethylhexyl acrylate by direct esterification, it is recommended to add sulfuric acid, a catalyst, at a level of 1 mol % and phenol, a polymerization inhibitor, at a level of 0.1 wt % of the (1) used. For ester-interchange reaction, the use of sulfuric acid, a catalyst, at a level of 1 mol % of the (2) used and sulfur, a polymerization inhibitor, at a level of 0.1 wt % of the (3) used is recommended. Those reactions are conducted at temperatures below 110°C to effect an approximately 95% yield.