Acid-base behavior in supercritical water: β-naphthoic acid-ammonia equilibrium

1997 ◽  
Vol 26 (1) ◽  
pp. 13-30 ◽  
Author(s):  
Tao Xiang ◽  
Keith P. Johnston
Keyword(s):  
Supercritical Water ◽  
Acid Base ◽  
Naphthoic Acid

Pulse polarographic study of the behaviour of some o,o'-dihydroxyazo-compounds

1989 ◽  
Vol 54 (5) ◽  
pp. 1219-1226 ◽  
Author(s):  
Enric Casassas ◽  
Miquel Esteban ◽  
Santiago Alier
Keyword(s):  
Carboxylic Acid ◽  
Reaction Mechanisms ◽  
Sulphonic Acid ◽  
Base Catalysis ◽  
Polarographic Study ◽  
Acid Base ◽  
Eriochrome Black T ◽  
Naphthoic Acid ◽  
Calcon Carboxylic Acid

The reduction of several o,o'-dihydroxyazo-compounds is studied by means of pulse polarographic techniques (DPP, NPP and RPP). The compounds studied are the following: 2-(2'-hydroxyphenylazo)-phenol (o,o'-dihydroxyazobenzene), 1-(2'-hydroxy-1'-naphthylazo)-2-naphthol-4-sulphonic acid (calcon or Eriochrome Blue Black R), 1-(2'-hydroxy-4'-sulpho-1'-naphthylazo)-2-hydroxy-3-naphthoic acid (calcon carboxylic acid), and 1-(1'-hydroxy-2'-naphthylazo)-6-nitro-2-naphthol-4-sulphonic acid (Eriochrome Black T). Correlations between Ip and Epand experimental variables (pH, T, conc.) and instrumental parameters (dropping time, t, and pulse magnitude, ΔE) are established. Reaction mechanisms formerly proposed are discussed on the basis of the new obtained results, and the ranges are defined where adsorption and/or acid-base catalysis are operative.

Solid Acid/Base Catalysis in Sub- and Supercritical Water

2018 ◽  
Vol 57 (16) ◽  
pp. 5495-5506 ◽  
Author(s):  
Makoto Akizuki ◽  
Yoshito Oshima
Keyword(s):  
Supercritical Water ◽  
Solid Acid ◽  
Base Catalysis ◽  
Acid Base

Acid-Base Relationships and Tautomeric Equilibria in m-Aminobenzoic Acid, 3-Amino-1-naphthoic Acid, and 4-Amino-2-naphthoic Acid

1961 ◽  
Vol 14 (2) ◽  
pp. 237 ◽  
Author(s):  
A Bryson ◽  
RW Matthews
Keyword(s):  
Aqueous Solution ◽  
Methyl Esters ◽  
Ionization Constants ◽  
Aminobenzoic Acid ◽  
Naphthalene Ring ◽  
Acid Base ◽  
Tautomeric Equilibria ◽  
Naphthoic Acid

The first and second ionization constants have been determined in aqueous solution of m-aminobenzoic acid, 3-amino-1-naphthoic acid, and 4-amino-2-naphthoic acid. From published values of the ionization constants for the methyl esters, the ionization constants have been evaluated for the four equilibria involved in each case and estimates have been made of the effects of the substituents NH3+ and NH2 on the ionization of the COOH, and of the substituents COOH and COO- on the ionization of the NH3+ group. These values and the tautomeric constants are interpreted in terms of structure and are discussed in relation to previous studies on substitution in the naphthalene ring.

Acid-Base Behavior of Organic Compounds in Supercritical Water

1994 ◽  
Vol 98 (32) ◽  
pp. 7915-7922 ◽  
Author(s):  
Tao Xiang ◽  
Keith P. Johnston
Keyword(s):  
Organic Compounds ◽  
Supercritical Water ◽  
Acid Base

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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