processes of producing 1 , 4 - dioxan - 2 - one are improved by the addition of a blocking agent to a crude reaction product containing p - dioxanone . the blocking agent reacts with unreacted starting materials in the crude reaction product to protect the active sites thereon with groups that do not initiate polymerization of p - dioxanone . the polymerization of p - dioxanone before its recovery from the process is thereby inhibited .