hydrolysis as shown in table i substitution of one of the tertiary alkyl groups by other groups such as methyl isobutyl or sec butyl results in marked decrease in hydrolytic stability the hydrolytic stability data for three commerical processing stabilizers is given in table ii the data show the extreme sensitivity of distearylpentaerythritol diphosphite to moisture tris 2 4 di t butylphenyl phosphite is as hydrolytically stable as the phosphites of the present invention but it has a very high melting point 180 u00b0 188 u00b0 c and requires specialized handling in the manufacturing process such as filtration of a dispersion or crystallization from a solvent such compounds cannot be flaked resulting in environmental hazard from dusting during handling operations the phosphites of the present invention have melting points in a 60 u00b0 100 u00b0 c range which is very convenient for flaking or if desired grinding operations in any manufacturing process yet the melting points are high enough to prevent fusion of flake or powder on storage and their relatively high molecular weight reduces loss at high temperatures usually encountered during processing of polymers into finished products as shown in table ii tris 2 4 di t butylphenyl phosphite possesses the hydrolytic stability of the phosphites of the present invention but it is considerably less.