The transesterification process is a well known reaction of organic chemistry. However, the monoesterification of unprotected polyols such as glycerol or sucrose is much more complex and the design of selective catalysts is becoming a huge challenge in order to avoid many protection and deprotection steps, harmful for the cost and the environmental impact of the resulting process. In this study, we showed that the control of the hydrophilicâlipophilic balance of heterogeneous catalysts is a crucial key in order to tune both the catalyst activity and the monoester selectivity. Indeed, whereas homogeneous guanidine led to low selectivity toward monoesters, its anchorage on a hydrophilic solid support such as silica allowed us to prepare two basic hybrid organicâinorganic materials able to selectively afford monoesters in high yield and in an environmentally-friendly process, at low temperature and starting from an equimolecular mixture of unprotected polyols and various fatty methyl esters.
酯交换过程是大家熟知的有机
化学反应。然而,未保护多元醇如
甘油或
蔗糖的单酯化反应要复杂得多,为了规避许多保护和去保护的步骤(这对成本和环境影响不利),设计选择性催化剂正成为一个巨大的挑战。在本研究中,我们展示了控制非均相催化剂的亲
水-疏
水平衡是调节催化剂活性和单酯选择性的关键。事实上,虽然均相
胍对单酯的选择性较低,但将其固定在
硅胶这样的亲
水性固体载体上,使我们能够制备两种基本的混合有机-无机材料,这些材料能在低温下,从等摩尔的未保护多元醇和各种
脂肪酸甲酯的混合物出发,通过环境友好型工艺高产率地选择性获得单酯。