Sensory evaluation of the synergism among ester odorants in light aroma-type liquor by odor threshold, aroma intensity and flash GC electronic nose.

Although esters were important odorants in light aroma-type liquor, it was still puzzling that sensory interaction between esters made the odor quality of light aroma-type liquor outstanding. The aim of the paper was to investigate perceptual interaction among esters. The odor thresholds of eighteen esters and 35 binary mixture were determined by a three-alternative forced-choice procedure. The relationship between odor threshold and carbon chain length of homologous ethyl esters was investigated. Moreover, 31 binary mixtures present either a synergistic effect or additive action. Furthermore, odor quality and odor intensity were determined by p/τ plot and σ/τ plot, respectively. From the p/τ plot, an ideal sigmoidal function for odor quality was obtained. From the σ/τ plot, for all 120 binary mixtures, just 9 mixtures were in the hyper-additivity area (σ > 1.05), and two were in the so-called perfect additivity area (0.95 < σ < 1.05). Almost one half (48%) showed compromise level. Finally, a significantly difference was observed by flash gas chromatography electronic nose (p < .05). Sensory analysis revealed that a mask effect of fruity note was occurred by adding ethyl phenylacetate at various levels (100, 2500, 58,000 ppb) to the fruit recombination and an enhancement effect of floral note was reported by adding phenylethyl acetate at low (1400 ppb) or high level (11,500 ppb). It was noticed that sweet note was significantly enhanced by adding phenylethyl acetate at peri-threshold (3200 ppb).

Thermodynamic and reactivity studies of a tin corrole-cobalt porphyrin heterobimetallic complex.

A heterobimetallic complex, (TPFC)Sn-Co(TAP) (TPFC = 5,10,15-tris(pentafluorophenyl)corrole, TAP = 5,10,15,20-tetrakis(p-methoxyphenyl)porphyrin), was synthesized. The complex featured a Sn-Co bond with a bond dissociation enthalpy (BDE) of 30.2 ± 0.9 kcal mol-1 and a bond dissociation Gibbs free energy (BDFE) of 21.0 ± 0.2 kcal mol-1, which underwent homolysis to produce the (TPFC)Sn radical and (TAP)CoII under either heat or visible light irradiation. The novel tin radical (TPFC)Sn, being the first four-coordinate tin radical observed at room temperature, was studied spectroscopically and computationally. (TPFC)Sn-Co(TAP) promoted the oligomerization of aryl alkynes to give the insertion products (TPFC)Sn-(CH[double bond, length as m-dash]C(Ar)) n -Co(TAP) (n = 1, 2, or 3) as well as 1,3,5-triarylbenzenes. Mechanistic studies revealed a radical chain mechanism involving the (TPFC)Sn radical as the key intermediate.

Characterization of the key aroma compounds in different light aroma type Chinese liquors by GC-olfactometry, GC-FPD, quantitative measurements, and aroma recombination.

The aroma profiles of five Chinese light aroma-type liquors were investigated in this study. Gas chromatography-olfactometry (GC-O) and GC-flame photometric detection (FPD) were employed to investigate aroma-active compounds. A total of 80 odorants were identified, including ten sulfur compounds. In addition, aroma-active compounds (FD≥16) were determined, according to quantitative study and odor activity values (OAVs). Finally 27 key aroma compounds, mainly possessing fruity and floral notes, were successfully used to simulate the aromas of Chinese light aroma-type liquors by dissolving them in 53% (v/v) hydroalcoholic solution in their natural concentrations. Moreover, the correlation between the key aroma compounds, seven sensory attributes and liquor samples was evaluated through partial least-squares regression analysis.

Synthesis, Electronic Structure, and Reactivity Studies of a 4-Coordinate Square Planar Germanium(IV) Cation.

A tetra-coordinate, square planar germanium(IV) cation [(TPFC)Ge](+) (TPFC = tris(pentafluorophenyl)corrole) was synthesized quantitatively by the reaction of (TPFC)Ge-H with [Ph3C](+)[B(C6F5)4](¯). The highly reactive [(TPFC)Ge](+) cation reacted with benzene to form phenyl complex (TPFC)Ge-C6H5 through an electrophilic pathway. The key intermediate, a σ-type germylium-benzene adduct, [(TPFC)Ge(η(1)-C6H6)](+), was isolated and characterized by single-crystal X-ray diffraction. Deprotonation of [(TPFC)Ge(η(1)-C6H6)](+) cation led to the formation of (TPFC)Ge-C6H5. [(TPFC)Ge](+) also reacted with ethylene and cyclopropane in benzene at room temperature to form (TPFC)Ge-CH2CH2C6H5 and (TPFC)Ge-CH2CH2CH2C6H5, respectively. The observed electrophilic reactivity is ascribed to the highly exposed cationic germanium center with novel frontier orbitals comprising two vacant sp-hybridized orbitals that are not conjugated to π-system. The three electron-withdrawing pentafluorophenyl groups on the corrole ligand also enhance the electrophilicity of the cationic germanium corrole.

Synthesis and reactivity studies of a tin(II) corrole complex.

A series of tris(pentafluorophenyl)corrole (TPFC) tin(IV) and tin(II) complexes were prepared and studied by various characterization techniques including (1)H, (19)F, and (119)Sn NMR and UV-vis spectroscopy, mass spectrometry, and single-crystal X-ray diffraction. The unusual 4-coordinate, monomeric, divalent tin(II) complex [(TPFC)Sn(II)](-) (2a) showed highly efficient reactivity toward alkenes and alkyl halides via a nucleophilic addition pathway leading to the quantitative formation of alkyl stannyl corrole compounds. DFT calculations confirmed the divalent nature of the tin center in 2a, and an NBO analysis showed about 99.99% Sn lone pair character, of which 83.6% was Sn 5s and 16.35% was Sn 5p character.