Example 1 Synthesis of 1,3:2,4-bis(3',4'-dimethylbenzylidene)sorbitol: At room temperature, D-sorbitol (9.11 g, 50 mmol) and 3,4-dimethylbenzaldehyde (13.4 g, 100 mmol) were dissolved in acetonitrile (100 mL) to form a white slurry. Subsequently, p-toluenesulfonic acid monohydrate (1.9 g, 10 mmol) solid was added to the mixture. The reaction mixture was reacted under magnetic stirring for 12 hours. Upon completion of the reaction, the resulting gel-like substance was washed sequentially with boiling water (200 mL x 2), cyclohexane (200 mL x 2) and boiling water (200 mL x 4) until no visible solvent remained. The washed product was dried in a vacuum oven at 110 °C for 12 h to afford 1,3:2,4-bis(3',4'-dimethylbenzylidene)sorbitol (20.5 g, 99%) as a white powder. The product was characterized by 1H NMR, 13C NMR, IR and GC/MS.
