Method of preparing symmetrical phosphate-based compound

A method of preparing a symmetrical phosphate-based compound, comprising synthesizing a compound represented by Chemical Formula 2 below by reacting a compound represented by Chemical Formula 1 below with a dinucleating agent in a hydrophobic solvent under a base-free condition, wherein the reaction is performed at 0 to 40° C.:

• wherein, in Chemical Formulas 1 and 2, R is a substituted or unsubstituted alkylene having 1 to 3 carbon atoms;
• X is chlorine (Cl), bromine (Br), fluorine (F), or iodine (I);
• and n is an integer from 1 to 5, wherein a substituent is independently selected from a halogen, a hydroxyl group, an alkyl group having 1 to 8 carbon atoms, a heteroalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the alkyl group, heteroalkyl group, and aryl group are independently substituted with a halogen.