8 9 A comparison was made between the composition of the recalcitrant organic matter (ROM) 10 isolated from a sandy forest soil as revealed by microwave assisted extractions and/or 11 hydrolyses and by usual pyrolysis techniques. Successive microwave irradiation treatments 12 were performed in H2O, 0.1 and 1 M HCl and 0.1 and 1 M KOH. At each step of the 13 treatment the insoluble residue was e...

In the title compound, 2CH(6)N(3) (+)·2Br(-)·C(12)H(24)O(6), the 18-crown-6 mol-ecule lies about an inversion center, whereas the guanidinium cation and bromide anion are in general positions. The guanidinium cations link with the bromide anions and the crown ether mol-ecules via N-H⋯O and N-H⋯Br hydrogen bonds, thus forming a three-dimensional network.