Comparative yield of Cis-1,4-polyisoprene from stem latex of four Landolphia species

The latex of a tropical liane, Landolphia owariensis, was coagulated with acetic acid. The dried coagulum was dissolved in benzene, the clear solution was decanted, when precipitation with acetone gave a polymer shown by IR and NMR spectroscopy to be cis-1,4-polyisoprene rubber. Similar investigations on three other Landolphia species were made to determine the relative yields of this natural cis-1,4-polyisoprene.