1: ion exchanger Lewatit MP 5 (OH-form) / methanol / 1 h / 50 °C / yield: 70-80 percent 2: 76.8 percent Chromat. / 1 N HCl / 2 h / 60 °C / further temperatures: 23, 40, 80 deg C; different times: 10, 20, 30, 60, 120 min View Scheme

1: ion exchanger Lewatit MP 5 (OH-form) / methanol / 1 h / 50 °C / yield: 70-80 percent 2: 21.9 percent Chromat. / 1 N HCl / 2 h / 60 °C / further temperatures: 23, 40, 80 deg C; different times: 10, 20, 30, 60, 120 min View Scheme

ion exchanger Lewatit MP 5 (OH-form) in methanol T=50°C; 1 h; yield: 70-80 percent;