There are described compounds of the formula
in which R 5 is methyl or halomethyl,

R 2 is -CN, -CONRyRz, -COOR 6 or - COS R 6 ,
R 1 and R 6 each represent hydrogen, a cation or an optionally substituted alkyl, alkenyl, alkynyl or aryl,
Ry and Rz each represent hydrogen, alkyl or aryl,
A represents hydrogen, or A and one of -XR 3 and -ZR 4 together form a double bond, and the other of -XR 3 and -ZR 4 represents -OR 10 or -NHR 11 in which R 10 is alkyl or acyl and R 11 is alkyl, aryl or acyl,
X and Z (when not forming part of a double bond with A), which may be the same or different, each represent oxygen, sulphur or a group -NR 7 -,
R 7 represents hydrogen or alkyl,
R 3 and R 4 each represent alkyl or R 3 and R 4 together form an optionally substituted alkylene or arylene chain
or -XR 3 and -ZR4 together form =C ( CN ) 2 or =NR8 , in which R 8 represents alkoxy, benzyloxy, hydroxy, phenyl, -NHCONH 2 , -NHCSNH 2 or -NH phenyl,
or one of -XR 3 and -ZR 4 is -OH (or an ester or ether thereof) and the other is hydrogen, -CN or -SO 3 ⊖ cation,
or -XR 3 and -ZR 4 together form carbonyl oxygen.
There are also described methods for making the compounds and herbicidal compositions containing them.