Tetraethylene Glycol → 2,4,6-Trimethylbenzyltetraethylene glycol

Participants

Reaction Conditions

Reaction Steps

95% Sodium hydride (40.85 g, 1.6 moles) was placed into a 3 L flask under argon and THF (1.2 L) at −10° C. was added. Dry tetraethylene glycol (500.0 g, 2.57 moles) was added slowly. The pot temperature was maintained below 15° C. during the addition. Once the NaH had reacted, a homogeneous solution resulted. 18C6 (3.9 g) and dimethyl-acetamide (DMAC, 500 mL) was added. Chloroisodurene (TMB-Cl, 98.6 g, 0.58 mole) dissolved in THF (500 mL) was added to pot over about 4 h. The reaction mixture was stirred for about 17 h at about 40° C. under argon. The reaction was monitored by tlc on silica gel plates, eluting with 10% MeOH/CH2Cl2 vs TMB-Cl. The reaction was complete; the TMB-Cl was consumed. The solvent was removed in vacuo; the resulting oil was extracted with CH2Cl2 (700 mL) and water (300 mL). The CH2Cl2 layer was separated, dried over MgSO4, filtered through fluted filter paper and concentrated in vacuo to leave an oil. A column was prepared with 600 g of silica gel and hexane as needed. The crude product was placed onto column with hexane and a minimum of t-butylmethyl ether (TBME, 100 mL) to make a clean transfer. The column was eluted with hexane (4 L) and then as follows: (2 L) 10% TBME/hexane; (2 L) 20% TBME/hexane; (4 L) TBME/hexane; (3 L) 40% TBME/hexane, and (2 L) TBME. Like fractions containing product were combined and concentrated in vacuo to give 140.2 g (73%). The product was characterized by nmr. 1H NMR[400 MHz, DMSO(d6)] □6.81 (s, 2H), 4.56 (t, 1H), 4.45 (s, 2H), 3.57-3.45 (m, 14H), 3.41 (t, 2H), 2.28 (s, 6H), 2.22 (s, 3H).

Provenance & Evidence