2.2 Preparation of DESs
ChCl was chosen as the HBA, and phenol (Pho),
p-toluenesulfonic acid
(TsOH),
benzoic acid
(BOA) and
hydroxylamine hydrochloride
(NH2OH•HCl) were selected as HBD, respectively. The
synthesis of DESs was carried out in a glass flask. The acceptor and
donor of the hydrogen bond were mixed according to molar ratio of 1/2,
1/1, 1/2, 1/2 to prepare ChCl-Pho (1:2), ChCl-TsOH (1:1), ChCl-BOA
(1:2), and ChCl-NH2OH•HCl (1:2), respectively, with the
structures shown in Figure 133-35. The mixtures were
heated with stirring for 1 h after the appearance of homogeneous liquid
phase in the oil bath.