Ethylparaben → Ethyl 4-(2-hydroxyethoxy)benzoate

104.9 g (842.5 mmol) 2-chloroethoxyethanol, 500 ml dimethylformamide (DMF), 70 g (421.2 mmol) ethyl 4-hydroxybenzoate, and 116.3 g (842.5 mmol) potassium carbonate were introduced into a flask in a nitrogen stream and stirred at 80° C. for 17 hours. The insolubles were filtered off, and the filtrate was concentrated, then introduced into a saline solution, extracted with ethyl acetate, washed with water and dried over magnesium sulfate anhydride, and the solution was concentrated to give 119 g crude ethyl 4-(2-hydroxyethoxy)benzoate. Subsequently, 150 ml ethanol and 200 ml aqueous solution of 33.7 g sodium hydroxide were added thereto, and the mixture was stirred at 70° C. for 2 hours. After the reaction solution was left and cooled, 72 ml conc. hydrochloric acid was added thereto on an iced bath, and the precipitates were filtered, and washed with water to give 89 g (76.2 mmol) 4-(5-hydroxy-3-oxapentyloxy) benzoic acid (compound (XIII) [R9, R10, R11, R12=H; X1=—(CH2CH2O)2—] in scheme (3)). Then, 800 ml toluene, 76.5 g (1060 mmol) acrylic acid and 10.1 g(53mmol)p-toluenesulfonicacidmonohydrate(referred to hereinafter as “PTSA”) were added thereto, and the mixture was esterified for 3 hours in a Dean-Stark tube. The insolubles were filtered, and washed with toluene, then suspended in water, filtered and dried to give 86 g of the desired product. The yield was 78%.