Novel heterocyclic disazo dyes containing pyrazole and phenylpyrazole. part 1: Synthesis, characterization, solvent polarity and acid-base sensitive characteristics

2021 ◽  
Vol 1231 ◽  
pp. 129960
Author(s):  
Aykut Demirçalı
Keyword(s):  
Solvent Polarity ◽  
Acid Base ◽  
Sensitive Characteristics

2-S-Methyl-5,5-dimethylimidazolin-4-one: chemical behaviour and crystal structure of its Δ1 tautomer

1991 ◽  
Vol 69 (3) ◽  
pp. 383-390 ◽  
Author(s):  
Franco Cristiani ◽  
Francesco A. Devillanova ◽  
Angelo Diaz ◽  
Francesco Isaia ◽  
Gaetano Verani ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chloroform Solution ◽  
Solvent Polarity ◽  
Ultraviolet Spectrum ◽  
Dielectric Constants ◽  
Quantum Mechanical ◽  
Monoclinic Space Group ◽  
Acid Base ◽  
Chemical Behaviour ◽  
Hydantoin Derivatives

2-S-Methyl-5,5-dimethylimidazolin-4-one can be crystallized as Δ1 or Δ2 tautomers, depending on the solvent polarity. The structure, solved on crystals obtained from benzene, showed it to be the Δ1 tautomer in the anti configuration. Δ1-2-S-Methyl-5,5-dimethylimidazolin-4-one is monoclinic, space group P21/c, with a = 8.347(1), b = 10.121(1), c = 9.996(3) Å, β = 107.20(2)°, R = 0.037 for 1395 independent reflections with I > lσ(I). The quantum mechanical (MNDO, PM3, and AMI) calculations indicate that among the four conformers the anti-Δ1 tautomer has both the lowest dipole moment and the lowest enthalpy of formation. The ultraviolet spectrum of the title compound has been recorded in solvents with different dielectric constants. The infrared spectra of the Δ1 and Δ2 solid samples are discussed relative to the v(NH) and v(CO) absorptions and in comparison with those recorded in carbon tetrachloride and in chloroform solution. Its acid–base behaviour has been studied by determining the pKa in aqueous solutions and the results are compared with those obtained for some related hydantoins. Key words: 2-S-methyl-5,5-dimethylimidazolin-4-one, tautomerism, hydantoin derivatives, crystal structure.

Molecular Switch Triggered by Solvent Polarity: Synthesis, Acid–Base Behavior, Alkali Metal Ion Complexation, and Crystal Structure

2003 ◽  
Vol 9 (3) ◽  
pp. 800-810 ◽  
Author(s):  
Gianluca Ambrosi ◽  
Paolo Dapporto ◽  
Mauro Formica ◽  
Vieri Fusi ◽  
Luca Giorgi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Alkali Metal ◽  
Metal Ion ◽  
Solvent Polarity ◽  
Molecular Switch ◽  
Acid Base ◽  
Metal Ion Complexation ◽  
Alkali Metal Ion ◽  
Ion Complexation

scholarly journals On the mechanism of photocatalytic reactions with eosin Y

2014 ◽  
Vol 10 ◽  
pp. 981-989 ◽  
Author(s):  
Michal Majek ◽  
Fabiana Filace ◽  
Axel Jacobi von Wangelin
Keyword(s):  
Solvent Polarity ◽  
Quantum Yields ◽  
Eosin Y ◽  
Acid Base ◽  
Absorption Properties ◽  
Direct Photolysis ◽  
Radical Chain ◽  
Chain Reactions ◽  
Photocatalytic Reactions

A combined spectroscopic, synthetic, and apparative study has allowed a more detailed mechanistic rationalization of several recently reported eosin Y-catalyzed aromatic substitutions at arenediazonium salts. The operation of rapid acid–base equilibria, direct photolysis pathways, and radical chain reactions has been discussed on the basis of pH, solvent polarity, lamp type, absorption properties, and quantum yields. Determination of the latter proved to be an especially valuable tool for the distinction between radical chain and photocatalytic reactions.

Higher Dietary Acidity is Associated with Lower Bone Mineral Density in Postmenopausal Iranian Women, Independent of Dietary Calcium Intake

2014 ◽  
Vol 84 (3-4) ◽  
pp. 0206-0217 ◽  
Author(s):  
Seyedeh-Elaheh Shariati-Bafghi ◽  
Elaheh Nosrat-Mirshekarlou ◽  
Mohsen Karamati ◽  
Bahram Rashidkhani
Keyword(s):  
Calcium Intake ◽  
Dietary Calcium ◽  
Dietary Calcium Intake ◽  
Dietary Intakes ◽  
Iranian Women ◽  
Acid Base Balance ◽  
Mineral Density ◽  
Acid Base ◽  
Base Balance ◽  
Dietary Acid

Findings of studies on the link between dietary acid-base balance and bone mass are relatively mixed. We examined the association between dietary acid-base balance and bone mineral density (BMD) in a sample of Iranian women, hypothesizing that a higher dietary acidity would be inversely associated with BMD, even when dietary calcium intake is adequate. In this cross-sectional study, lumbar spine and femoral neck BMDs of 151 postmenopausal women aged 50 - 85 years were measured using dual-energy x-ray absorptiometry. Dietary intakes were assessed using a validated food frequency questionnaire. Renal net acid excretion (RNAE), an estimate of acid-base balance, was then calculated indirectly from the diet using the formulae of Remer (based on dietary intakes of protein, phosphorus, potassium, and magnesium; RNAERemer) and Frassetto (based on dietary intakes of protein and potassium; RNAEFrassetto), and was energy adjusted by the residual method. After adjusting for potential confounders, multivariable adjusted means of the lumbar spine BMD of women in the highest tertiles of RNAERemer and RNAEFrassetto were significantly lower than those in the lowest tertiles (for RNAERemer: mean difference -0.084 g/cm2; P=0.007 and for RNAEFrassetto: mean difference - 0.088 g/cm2; P=0.004). Similar results were observed in a subgroup analysis of subjects with dietary calcium intake of >800 mg/day. In conclusion, a higher RNAE (i. e. more dietary acidity), which is associated with greater intake of acid-generating foods and lower intake of alkali-generating foods, may be involved in deteriorating the bone health of postmenopausal Iranian women, even in the context of adequate dietary calcium intake.

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