HETEROCYKLISKA FOERENINGAR

A herbicidal compound of formula (I) : in which Ar is an optionally subsitituted aryl or heterocyclic ring system; R and R are independently selected from H, optionally substituted alkyl, alkenyl or alkynyl, halogen, NRR, or R and R together with the carbon to which they are attached form an optionally substituted alkenyl or cycloalkyl group; R is CO2R , CN, COR , CH2OR , CH(OH)R , CH(OR )R , CH2OSO2R , CH2OSO3R , CH2ONR R , CSNH2, COSR , CSOR , CONHSO2R , CONR R , CONHNR R , CONHNR R R Y, CO2M or COON=CR R ; M is an agriculturally acceptable cation; Y is an agriculturally acceptable anion; R , and R are independently selected from H or an optionally substituted alkyl, aryl, alkenyl or alkynyl group; R , R , R , R , R and R are independently selected from H or an optionally substituted alkyl, alkenyl, aryl or alkynyl group or any two of R , R , R , R , R and R together with the atom to which they are attached form a cycloalkyl or heterocyclic ring; R and R may also be a heterocyclic ring; W is O or NR where R is H or lower alkyl; X is (CH2)n, CH=CH, CH(OR)CH2, COCH2; where R is H or an optionally substituted alkyl, aryl, alkynyl or alkynyl group; and n is O, 1 or 2. Process for the preparation of these compounds and compositions containing them are also described.