<http://webisa.webdatacommons.org/165596015> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/ns/prov#Entity> . <http://webisa.webdatacommons.org/prov/104928826> <http://www.w3.org/ns/prov#wasDerivedFrom> <http://webisa.webdatacommons.org/165596015> . <http://webisa.webdatacommons.org/165596015> <http://www.w3.org/ns/prov#wasQuotedFrom> <freepatentsonline.com> . <http://webisa.webdatacommons.org/165596015> <http://www.w3.org/ns/prov#value> "in which:R1 and R2 independently represent a hydrogen atom, a C1-C5 alkyl group such as methyl, ethyl or propyl, or an aryl group,Y is chosen from O, S, ???SO2???," .