The carbonyl frequency in semicarbazides, semicarbazones, and pyrazolecarboxamides is higher than that in ureas. A phenyl group attached to the third nitrogen atom of semicarbazides lowers the carbonyl frequency. A phenyl group substituted on the first nitrogen atom shifts the carbonyl absorption in semicarbazides to a higher frequency region than do alkyl groups.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.