methyl 2 ethylpropyl phenyl ethyl and tertiaryoctyl the two alkyl groups are in the 2 4 positions or 2 6 positions a particularly preferred species is bis 2 4 ditertiarybutylyalkylphenyl pentaerythritol diphosphite another preferred species is bis 2 6 ditertiarybutylphenyl pentaerythritol diphosphite another especially desirably phosphite is di 2 4 ditertiarybutylphenyl pentaerythritol diphosphite the phosphite esters may be made by a variety of methods the dialkyl pentaerythritol diphosphites may be prepared via methods described in the teachings of u s pat nos 4 305 866 5 137 950 4 064 100 or other means described in the literature other phosphite antioxidants which can be employed include trioctylphosphite trilaurylphosphite tridecylphosphite octyl diphenylphosphite tris 2 4 di t butylphenyl phosphite tris nonylphenyl phosphite hexa tridecyl 1 1 3 tris 2 methyl 4 hydroxy 5 t butylphenyl butane triphosphite tetra c 12 15 alkyl 4 4 39 isopropylidenediphenol diphosphite tetra tridecyl 4 4 39 butylidenebis 3 methyl 6 t butylphenol diphosphite hydrogenated 4 4 39 isopropylidenediphenol polyphosphite distearyl pentaerythritol diphosphite phenyl 4 4 39 isopropylidenediphenol pentaerythritol diphosphite bis 2 4 di t butylphenyl pentaerythritol diphosphite bis 2 6 di t butyl 4 methylphenyl pentaerythritol diphosphite di nonylphenyl pentaerythritol diphosphite and 4 4 39 isopropylidenebis 2 t butylphenol di.