Abstract The aim of this present paper is investigation of the reactions of preparation of unsymmetrical reactive carbonates from the corresponding symmetrical carbonates and different type of alcohols. The asymmetrical carbonates represent alternative reagents (mild, efficient) for alkoxycarbonylation of amines and amino-acids. The synthesized compounds were characterized by spectroscopic and chromatographic methods. A general method for preparation of asymmetrical carbonates was develop from N,N’-disuccinimidylcarbonate. The yield of this reactive carbonates depends by alcohols reactivity, hindered factor and stability of final product.