The ionization constants of vanillin and two of its isomers

Robinson, R. A.; Kiang, A. K.

doi:10.1039/tf9555101398

Cited by 32 publications

(16 citation statements)

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“…According to the structures of plant tissue material and the molecular markers of BBOA reported in the literature, 64 tentative molecular structures of these chromophores can be suggested ( Figure S12). For example, based on the molecular formula and on the distinctive absorption spectrum, 68 Flavone backbone is the core structure of natural pigments and condensed tannins. 73 Condensed tannins are the most abundant polyphenols in nature, widely found in all families of plants.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles

Lin

Aiona

Liu

et al. 2016

Environ. Sci. Technol.

283

372

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Emissions from biomass burning are a significant source of brown carbon (BrC) in the atmosphere. In this study, we investigate the molecular composition of freshly emitted biomass burning organic aerosol (BBOA) samples collected during test burns of sawgrass, peat, ponderosa pine, and black spruce. We demonstrate that both the BrC absorption and the chemical composition of light-absorbing compounds depend significantly on the type of biomass fuels. Common BrC chromophores in the selected BBOA samples include nitro-aromatics, polycyclic aromatic hydrocarbon derivatives, and polyphenols spanning a wide range of molecular weights, structures, and light absorption properties. A number of biofuel-specific BrC chromophores are observed, indicating that some of them may be used as source-specific markers of BrC. On average, ∼50% of the light absorption in the solvent-extractable fraction of BBOA can be attributed to a limited number of strong BrC chromophores. The absorption coefficients of BBOA are affected by solar photolysis. Specifically, under typical atmospheric conditions, the 300 nm absorbance decays with a half-life of ∼16 h. A “molecular corridor” analysis of the BBOA volatility distribution suggests that many BrC compounds in the fresh BBOA have low saturation mass concentration (<1 μg m–3) and will be retained in the particle phase under atmospherically relevant conditions.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles

Lin

Aiona

Liu

et al. 2016

Environ. Sci. Technol.

283

372

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“…Measurem e nts were mad e at two wavele ngth s, usin g 1 cm cells . In calculating valu es of pK a small correc ti on was made for the effect of m-nitroph e nol on the p(a l-/y d valu e of the buffer solution [10].…”

Section: Resultsmentioning

confidence: 99%

Dissociation constant of m-nitrophenol in 50 wt percent methanol-water solvent from 25 to 40 C and related medium effects

Steel

Robinson

Bates

1967

J. RES. NATL. BUR. STAN. SECT. A.

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The di ssociation co nstant of m-nitrophenol in 50 wt percent methanol-water as solvent ha s been determined at 25, 30, 35, and 40°C. A spectrophotometric method was used, together with acidity functions for buffer so lutions in 50 percent methanol derived from previous emf meas ure ments. Values of the e nthalpy and entropy c hanges on dissociation of the phenol have been calculated. A co mpariso n with co rresponding values for the dissociation of m-nitrophenol in aqueous so lution affords a measure of the med ium effect. The medium effect for m-nitrophenollies intermediate between that for Q·nitrophenol and that for p-nitrophenol.

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“…These p(aHYcd values are altered to a small extent by the phenol in the buffer solution whose dissociation into hydrogen ions increases the acidity of the buffer solution slightly. The correction to the p(aHYcl) values has already been considered [4].…”

Section: Outline Of Methodsmentioning

confidence: 99%

“…The dissociation of the anilinium ion or a substituted anilinium ion can be represented as with a dissociation constant (4) or pK=-log mH + -Iog a/(l-a)…”

Section: Outline Of Methodsmentioning

confidence: 99%

The dissociation constants of some disubstituted anilines and phenols in aqueous solution at 25 C

Robinson¹

1967

J. RES. NATL. BUR. STAN. SECT. A.

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Th e di ssoc ia ti on co nsta nts of s ix di s ub stituted a nilin es and of fiv e di s ub s titut ed ph e nols in a qu eo us so lution a t 25°C hav e bee n meas ured u sin g th e s pec troph otome tri c method. Co nsid era tio n is give n to th e ex t ent to whi c h these di ssoc iati o n co nstants can be predicted from co rrespo ndin g values for monos ub s titut e d anil in es and Dh en ols . In additi on , th e qu esti on as to wh e th e r th e pK value of a su b· stituted anil ine c an be pred icted from th e pK value of a phenol with subs titu ents in the sa me position s is also inv es ti gate d. ~ Key W ord s: Di ssociation co ns ta nt, subs titute d a nilin es, s ubs tituted ph enols.

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The ionization constants of vanillin and two of its isomers

Abstract: By spectrophotometric methods the thermodynamic ionization constants of vanillin, isovanillin and o-vanillin at 25" have been found to be 4.02 x 10-8, 1.29 x 10-9 and 1.23 x 10-8 respectively.

Cited by 32 publications

References 0 publications

Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles

Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles

Dissociation constant of m-nitrophenol in 50 wt percent methanol-water solvent from 25 to 40 C and related medium effects

The dissociation constants of some disubstituted anilines and phenols in aqueous solution at 25 C

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