Chemical constituents and structural characteristic of the combined acids in brown coal resin from Chinese brown coal waxes

doi:10.3321/j.issn:0253-9993.2001.02.025

Abstract：The acids combined to form esters, LHZZS,XDZZS and SLZZS, the fractio ns in brown coal resins from brown coal waxes from Liaohu, Xundian (Yunnan Province) and Shulan(Jilin Province) brown coal respectively, were derived by CH 2N2 to methyl esters and their chemical constituents and structural characteristic were studied on GCMS. The experimental results demonstrate that normal fatty acids from C12 to C28are dominant in combined acid fraction, but concen trated mainly in low carbon number (C16,C18,C20,C22). Fatty acid with highest content both in LHZZS and XDZZS is eicosanoic acid, the next, hexadecanoic acid. In SLZZS, the normal fatty acids are absolutely dominant compositions, hexadecanoic acid with the highest content, the next, benzoic acid; Tricyclic diterpanoic acids and pentacyclic triterpanoic acids, such as dehydroabietic acid, pimaric acid, isopima ric acid, sandaracopimaric acid, tetrahydroabietic acid, abietic acid,C32 and C33hopanoic acid, etc., exist in the combined acid for each sample, but compare d with free acid fraction of brown coal resin, especially in LHZZS and XDZZS, the amount is quite lower, which made the huge difference between free acid fraction and combined acid fraction; there are more branched fatty acids and benzoic acid, phenolic compounds in SLZZS. From the chemical constituents and their distri bution characteristic of combined acid, free acid and hydrocarbon fraction, it can be concluded that the original plants and the existing environment of Liaohu brown coal wax is much similar to that of Xundian brown coal wax, but basically different from the resource of Shulan brown coal wax.