Abstract: This invention provides new compounds of formula I, ##STR1## wherein X is sulphur or oxygen,R is alkyl of 3 to 7 carbon atoms or cycloalkyl of 3 to 7 carbon atoms, cycloalkyl of 3 to 7 carbon atoms monosubstituted by alkyl of 1 to 4 carbon atoms, .alpha.-dialkylpropinyl of 5 to 9 carbon atoms or .alpha.-dialkyl-allyl of 5 to 9 carbon atoms, hydroxyalkyl of 2 to 7 carbon atoms or phenoxyalkyl of 8 to 11 carbon atoms, the oxygen atom of the last two radicals being separated by at least two carbon atoms from the nitrogen atom to which R is bound,R.sub.1 isI. hydrogen or alkyl of 1 to 4 carbon atoms in the 2,3,6 or 7 position, orIi. chlorine or bromine, in the 2, 3 or 7 position,Iii. nitro or --NHA wherein A is alkanoyl of 1 to 4 carbon atoms, in the 2, 3 or 7 position, orIv. fluorine, cyano or COOB, wherein B is alkyl of 1 to 4 carbon atoms, in the 2 or 3 position, andR.sub.2 isI. hydrogen or alkyl of 1 to 4 carbon atoms in the 2, 3, 6 or 7 position,Ii. chlorine or bromine, in the 2, 3 or 7 position, orIii.