bromine and iodine the alkyl and alkoxy groups contemplated by the invention comprise both straight and branched carbon chains of from one to about six carbon atoms representative of such groups are methyl ethyl isopropyl butyl pentyl 3 methylpentyl methoxy ethoxy i propoxy t butoxy n hexoxy 3 methylpentoxy and the like the preferred compounds are those of formula i where x structures a b or c and r 1 and r 2 are the same or different and are hydrogen or halogen r 3 is hydrogen r 4 and r 5 are the same or different and are an alkyl of from one to four carbon atoms r 6 is hydrogen or an alkyl of from one to six carbon atoms and n is an integer from three to five the more preferred compounds are those of formula i where x structures a or b and r 1 and r 2 are hydrogen r 3 is hydrogen n is three or five r 4 and r 5 are methyl and r 6 is hydrogen or an alkyl of from one to two carbon atoms the above compounds may be prepared by reacting a substituted 1 3 dioxo 2h isoindol 2 yl phenol with a halogenated alkyl substituted carboxylic acid ester in solvent at room temperature in the preferred reaction the substituted.