Compounds having the formulas below. R is an aromatic-containing group. Each M is an alkali metal. Each m is a positive integer. The value of n is a positive integer. The value p is 0 or 1. If p is 0 then n is 1. A thermoset made by curing a composition containing the below phthalonitrile monomers. A method of reacting a diphenyl acetylene compound with an excess of an aromatic diol in the presence of an alkali metal carbonate to form the above oligomer. A method of reacting a phenoxyphthalonitrile with an acetylene compound to form the phthalonitrile monomer below.