Polyalkyl p-phenylenediamine anti-degradants and intermediates and preparation method thereof

A compound of Formula I:

• wherein each R1 is independently a C1-C18 chain hydrocarbon group or a C3-C18 alicyclic hydrocarbon group, a is an integer of 1 to 5, at least one of the one or more R1 is a methyl, and when a is 1, R1 is at para-position to —NH group, and when a is 2 to 5, one of the R1 is at the para-position to —NH group;
• R2, R3, R4, and R5 are each independently H, a C1-C18 chain hydrocarbon group, or a C3-C18 alicyclic hydrocarbon group, and at least one of the R2, R3, R4, and R5 is not H;
• and
• R6 and R7 are each independently a C1-C18 chain hydrocarbon group or a C3-C18 alicyclic hydrocarbon group, or R6 forms a C3-C18 aliphatic ring with R7.