By means of Friedel-Crafts reaction, the following compounds were prepared from 4-methyl-imidazolone-2 and four different w-carbethoxy acyl halides: 4-methyl-5-(8-canbethoxy-y-methyl-butyryl)-imidazolone-2, 4-methyl-5-(8-carbethoxy-y, y-dimethylbutyryl)-imidazolone-2, 4-methyl-5-(ω-carbethoxy-n-nonanoyl)-imidazolone-2, and 4-methyl-5-(ω-canbethoxy-n-heptadecanoyl)-imidazolone-2. With PtO₂ as catalyst, they were readily reduced to the four corresponding imidazolidone compounds. These compounds were hydrolyzed with 1 N NaOH and then followed by acidification to give the following acids: 4-methyl-5-(δ-carboxy-y-methylbutyl)-imidazolidone-2, 4-methyl-5-(δ-carboxy-y, y-dimethyl:butyl)-imidazolidone-2, 4-methyl-5-(ω-carboxy-n-nonanyl)-imidazolidone-2, and 4-methyl-5-(w}carboxy-n-heptadecanyl)-imidazolidone-2. Microbiological tests indicated that the first three acids are good anti-biotins towards lactobacillus casei and saccharomyces cerevisiae strain No, 139. Due to its extreme insolubility in water, the last compound has not yet been tested for its microbiological activity.