Structural investigation of lac resin. Part XI. The role of acetalisation in resin formation, and the configuration of jalaric acid
The alkali-stable linkage in shellac has now been recognised as acetalic in nature, in the light of the formation of dioxolans from threo-9,10,16-trihydroxyhexadecanoic (aleuritic) acid and the terpene aldehydes of shellac. A method of estimation of the extent of acetalisation is presented. The minor terpene constituents of shellac have now been identified as of the oxo-ether type, previously prepared from the major components. Evidence correlating the configuration of 2-epi-shellolic acid with that of the major aldehydic acid is presented.