Studies of some aliphatic constituents of shellac

Abstract

Hydrolysis of lac resin yields a mixture of acids among which only two - aleuritic (up to 40%) and shellolio (up to 5%) - have been adequately characterised and examined by several investigators. The work embodied in this thesis represents some studies of the aliphatic acids in lac hydrolysate. The presence of a range of non-hydroxy acids (1.1%) 6-hydroxytetra- decanoic acid (not less than 8%), l6~hydroxyhexadecanoic acid and snother monohydroxyhexadecanoic acid has been demonstrated. The 6-hydroxytetradecanoic acid has been shown to be identical with butolic acid recently isolated by chemists of the Indian Lac Research Institute but considered by them to be a C1B hydroxy acid. The other acids have not previously been reported as constituents of lac resin. Reversed-phase chromatography was found to be unsuitable for the examination of lac acids, probably due to their highly hydroxylated nature. Dehydroxylation experiments on lac acids by lodlnatlon- deiodination and by bromination-debrominatlon revealed the presence of hydroxylated tetradecanoic and hexadecanoic acids; brominatlon- debrominatlon reactions also showed the presence of small amounts of vicinal dihydroxy acids of these two series. Partition of lac acids between petroleum ether and 80% aqueous methanol and subsequent examination of the petroleum other-soluble material (1.1%) revealed the presence of dodecanoic (trace). tetradec-9-onoic and tetradecanoic acids (25%), hexadec-9-enoic acid (13%), hexadecanoic acid (53%), octadec-9-enoic acid (7%) and octadecanoic acid (2%). Examination of lac acids by adsorption, gas-liquid and thin layer chromatography showed the presence of 6-hydroxy-tetradecanoic acid (8% or more of lac acids), 16-hydroxy-hexadeoanoic acid and another monohydroxyhexadeoanoic acid.