Method for preparing a benzophenone derivative

A method comprising the steps of a) contacting in the presence of a solvent 4-hydroxyphenone and a salt thereof with propylene oxide in a reactor heated to a temperature in the range of from 100° C. to 200° C. to form a poly(propylene oxide)-benzophenone intermediate;

• then b) contacting the intermediate with ethylene oxide in the heated reactor to form an alkoxylated benzophenone substituted with propylene oxide groups and ethylene oxide groups, wherein the mole:mole ratio of the benzophenone to the salt thereof is in the range of from 98:2 to 80:20;
• the mole:mole ratio of the propylene oxide to the benzophenone is in the range of from 1:1 to 20:1;
• and the mole:mole ratio of the ethylene oxide to the benzophenone is in the range of from 5:1 to 50:1.