A compound according to formula: the compound of formula being selected from the group consisting of (i) compounds of formula in which R 1 is a halogen atom selected from Cl and F, R 2 -R 6 are independently hydrogen, halogen, hydroxyl, -C 1 -C 4 alkyl, -C 1 -C 4 alkoxy, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least one of R 2 -R 6 is other than hydrogen and R 2 -R 6 include no more than one acyloxy and no more than one halogen, and (ii) compounds of formula in which R 1 is Br, and (a) R 2 -R 6 are independently hydrogen, halogen, hydroxyl, C 1 -C 4 alkyl, -C 1 -C 4 alkoxy, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least one of R 2 -R 6 is a hydroxyl in the ortho position of the benzene ring and R 2 -R 6 include no more than one acyloxy and no more than one halogen, or (b) R 2 is OR 8 in which R 8 is -C R 10, in which R 10 is -C 1 -C 4 alkyl, R 3 is -C 1 -C 4 alkyl or -C 1 -C 4 alkoxy, and R 4 -R 6 are hydrogen, including salts and hydrates of these compounds, or (c) R 2 -R 6 are independently hydrogen, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least two of R 2 -R 6 are other than hydrogen. (i) compounds of formula in which R 1 is a halogen atom selected from Cl and F, R 2 -R 6 are independently hydrogen, halogen, hydroxyl, -C 1 -C 4 alkyl, -C 1 -C 4 alkoxy, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least one of R 2 -R 6 is other than hydrogen and R 2 -R 6 include no more than one acyloxy and no more than one halogen, and (ii) compounds of formula in which R 1 is Br, and (a) R 2 -R 6 are independently hydrogen, halogen, hydroxyl, C 1 -C 4 alkyl, -C 1 -C 4 alkoxy, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least one of R 2 -R 6 is a hydroxyl in the ortho position of the benzene ring and R 2 -R 6 include no more than one acyloxy and no more than one halogen, or (b) R 2 is OR 8 in which R 8 is -C R 10, in which R 10 is -C 1 -C 4 alkyl, R 3 is -C 1 -C 4 alkyl or -C 1 -C 4 alkoxy, and R 4 -R 6 are hydrogen, including salts and hydrates of these compounds, or (c) R 2 -R 6 are independently hydrogen, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least two of R 2 -R 6 are other than hydrogen. (a) R 2 -R 6 are independently hydrogen, halogen, hydroxyl, C 1 -C 4 alkyl, -C 1 -C 4 alkoxy, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least one of R 2 -R 6 is a hydroxyl in the ortho position of the benzene ring and R 2 -R 6 include no more than one acyloxy and no more than one halogen, or (b) R 2 is OR 8 in which R 8 is -C R 10, in which R 10 is -C 1 -C 4 alkyl, R 3 is -C 1 -C 4 alkyl or -C 1 -C 4 alkoxy, and R 4 -R 6 are hydrogen, including salts and hydrates of these compounds, or (c) R 2 -R 6 are independently hydrogen, acyloxy, phenyl, benzyl, or -C R 7 where R 7 is -C 1 -C 4 alkyl, including salts and hydrates of these compounds, wherein at least two of R 2 -R 6 are other than hydrogen.