Transalkylation: A new method for structural characterization of humins

Three humin samples, one from a calcic soil (Marais de Rochefort, MAT) and two from two horizons of a calcic peat (Marais Poitevin, MP35 and MP79), both from the Western part of France, were transalkylated using CF 3SO 3H as catalyst and benzene as acceptor and solvent. The reaction, used previously to study the kerogen of ancient sediments, was applied for the first time to humin. The main series of products were alkyl benzenes, phenyl-substituted fatty acids, 1,1-diphenylalkanes, diphenyl-substituted fatty acids, alkyl naphthalenes and aliphatic compounds. The alkyl benzenes indicate the presence of alkyl chain substituents on the aromatic part of the humin matrix. Acidic chains were also identified as substituents, unlike previous results for kerogen. The filiation between phenyl- and diphenyl-substituted compounds, demonstrated in the case of kerogen, could not be observed for the humin samples. However, as a result of the high amount of mineral matter in the MAT sample, alkyl naphthalenes undoubtedly originated from alkyl benzenes via alkyl tetralins, as observed in the case of kerogen.