Patent ID: 6849747

Claim:
A compound of Structure (I) or Structure (II): wherein R is independently selected from the group consisting of hydrogen, lower alkyl groups containing 1-4 carbon atoms, lower alkoxy groups, chlorine and fluorine; R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of lower alkyl groups containing 1-4 carbon atoms, lower alkoxy groups, and fluorine; with the proviso that only one of R 1 and R 2 is fluorine, only one of R 3 and R 4 is fluorine, and wherein at least one of R 1 , R 2 , R 3 , and R 4 is a lower alkyl group; further wherein no more than two of said R 1 -R 4 groups comprise fluorine.