Use of phenylenediamines and hindered phenols to inhibit polymer formation during the manufacture of acrylonitrile

A method for inhibiting the polymerization of acrylonitrile during the manufacture of acrylonitrile comprising

• providing a reaction mixture for the manufacture of acrylonitrile in the absence of a material selected from the group consisting of an initiator and a catalyst which are not natural byproducts of the reaction to manufacture acrylonitrile;
• and
• adding to said reaction mixture a mixture of a para-phenylenediamine and a hindered phenol at a molar ratio of at least about 2:1 and in an amount that is sufficient to inhibit polymerization of said acrylonitrile but insufficient to initiate polymerization,
• wherein said hindered phenol is selected from the group consisting of 2,6-di-tert-butyl phenol;
• 2,6-di-tert-butyl-4-methyl phenol;
• 2,6-di-methyl phenol;
• 2,4,6-tri-tert-butyl phenol;
• 2,6-di-tert-butyl-4-amine phenol;
• and 2,4-di-tert-butyl phenol.