Alkaline hydrolysis of dimethyl terephthalate in the presence of [LiAl2(OH)6]Cl·2H2O

The alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl2(OH)6]Cl has been investigated to demonstrate a possible application of anion exchange facility of layered double hydroxides (LDHs) to control chemical reactions. The results show that (i) in the alkaline hydrolysis of DMT in the presence of [LiAl2(OH)6]Cl, most of the interlayer Cl− of [LiAl2(OH)6]Cl is quickly replaced by OH− in the alkaline solution because the LDH host favors OH− more; (ii) the alkaline hydrolysis of DMT in the presence of [LiAl2(OH)6]Cl is faster than the reaction of DMT and [LiAl2(OH)6]OH; (iii) The hydrolysis of DMT in a buffer solution of pH≈8 takes longer time to reach equilibrium than the alkaline hydrolysis of DMT in the presence of [LiAl2(OH)6]Cl. It is believed that the selective anion exchange chemistry of the LDH plays a key role in storage and controlled release of active reactant, that is, OH−, thus make the hydrolysis proceeds in a controlled way.

XRD patterns of the solid products of the alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl2(OH)6]Cl at 70 °C halted at different time, which shows that [LiAl2(OH)6]Cl turns out to be [LiAl2(OH)6]OH, and [LiAl2(OH)6]2TP forms gradually. In this reaction, the alkaline hydrolysis of DMT is controlled by replacement of Cl− in [LiAl2(OH)6]Cl by OH−, and subsequent replacement of OH− in [LiAl2(OH)6]OH by terephthalate anion.Figure optionsDownload as PowerPoint slide