 The conversion rate is low and only 0.36 g of angelic acid could be obtained from 13 g of tiglic acid after 43-day irradiation with a 500-watt lamp.Being the "cis" isomer, angelic acid has a lower melting point and higher acid dissociation constant than tiglic acid, in accordance to usually observed trends.Angelic acid reacts with hydrobromic acid and bromine producing bromovaleric and dibromovaleric acids, respectively, with a yield of 60–70%.