Dragoco Gerberding & Co AG

C21H24N2O6, orthorhombic, P212121 (No. 19), a = 6.285(2) Å, b = 9.044(4) Å, c = 35.52(2) Å, V = 2019.0 Å3, Z = 4, R(F) = 0.095, wRref(F2) = 0.279, T = 295 K.

The title compound is monoclinic, space group P2₁, a 9.981(3), b 10.765(3), c 9.565(3) Å, β 91.04(1)°, Z = 2, R_gt(F) = 0.046, wR_ref(F²) = 0.091, T = 295 K.At. coordinates are given.All intramol. bond lengths are normal.The mols. are mainly held together by Van der Waals forces and weak intermol. electrostatic interactions between O2...H₂O (2.522 Å) and O3...Br (3.248 Å), resp.Both distances are slightly shorter than the corresponding sums of the associated Van der Waals radii.Without implying chem. interaction, the packing scheme is characterized by chains of Br atoms running along [010] with d(Br...Br) = 6.013 Å, and by the Br.-S axis, which is approx. pointing towards the next Br viewed along the [100] direction.

3-Mercapto-2-methylpentan-1-ol was first detected in a complex thermally processed flavor and finally isolated from raw onions. The chemical structure of this new compound was identified by MS and (1)H NMR measurement and synthesis of the proposed structure. Sensory evaluation at different concentrations indicated that the flavor quality is strongly dependent on concentration. At low concentration (0.5 ppb) a pleasant meat broth, sweaty, onion, and leek-like odor can be perceived. On the basis of some isolation experiments and volatiles occurring in raw onions, a formation pathway is proposed. As one intermediate 3-mercapto-2-methylpentanal, another new strong flavor compound, was suggested. The presence of this compound in raw onions was confirmed by synthesis and comparison of MS and chromatographic data.