Method of synthesizing a substantially monodispersed mixture of oligomers

A method of synthesizing a substantially monodispersed mixture of oligomers comprising polyethylene glycol moieties of compounds represented by Formula IV, said method comprising steps of:

• (a) reacting a substantially monodispersed mixture of compounds having the structure of formula I
• wherein R1 is a lower or higher alkyl, n=1 to 20, and X+ is a positive ion with tert-butyl acrylate in the presence of a base under conditions sufficient to provide compound of Formula II
• wherein R1 is a lower or higher alkyl, n=1 to 20;
• (b) converting the compound of Formula II to a compound of Formula III in the presence of acid and water, wherein the acid is selected from the group consisting of p-Toluene sulphonic acid (PTSA), Pyridinium p-toluenesulfonate (PPTS), Trifluoro acetic acid (TFA), Methane sulphonic acid (MeSO3H), Ethane sulphonic acid (EtSO3H), Benzene sulphonic acid (PhSO3H) and Sulphuric acid (H2SO4)
• wherein R1 is a lower or higher alkyl, n=1 to 20;
• and
• (c) dissolving the compound of Formula III in at least one aprotic solvent, adding thionyl chloride at a temperature from about 0 to 40° C. to form an acid chloride and activating the acid chloride in the presence of N-hydroxysuccinimide and an aliphatic amine selected from the group consisting of monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, mono-n-butylamine, di-n-butylamine, tri-n-butylamine, monocyclohexylamine, dicyclohexylamine and mixtures thereof, to yield the compound of Formula IV