2.2.1. Synthesis of Triethoxysilane Cholinium Derivative (Si-[Chol][Cl])

3-(chloropropyl)triethoxysilane (8 mL, 33.3 mmol, 1.1 equivalents) and 2-dimethylaminoethanol (3 mL, 30.0 mmol) were added to a wide-neck glass vial. The reaction mixture was heated under microwave irradiation for 30 min at 85 °C until the formation of a single-phased yellow and viscous oil. The crude was then washed with diethyl ether and dried under vacuum to give 9.15 g (85%) of the pure final product designated as Si-[Chol][Cl].

¹H NMR (400 MHz, CDCl₃, rt) δ = 4.08 (s, 2H, H-1), 3.90–3.80 (m, 6H, H-3), 3.66 (q, 4H, H-2, H-4), 3.44–3.35 (m, 6H, H-7), 1.91–1.81 (m, 2H, H-5), 1.27–1.18 (m, 9H, H-8), 0.66 (t, 1H, H-6) ppm (see Figure 1 for proposed numbering).

Proposed numbering scheme for triethoxysilane cholinium ionic liquid Si-[Chol][Cl].