Another preferred subgroupincludes the compounds wherein the total number of carbons in R and R.sup.3 is 2 or 3, i.e. both R and R.sup.3 may be methyl or one ethyl and the other methyl, and X is hydrogen, halo, hydroxy, alkoxy of 1 through 3 carbons, trifluoromethyl or alkyl of 1through 3 carbons.