Titrable acid

Gould, I. A. and Frantz, R. S. 1945. Some relationships between pH, titrable acidity, and the formol titration in milk heated to high temperatures. J. Dairy Sci. 28, 387-399. 

Deacidification Titrable Acidity Total Soluble Color ... 

Fig. 4. Effect of 2.5 ml (250 USP units) of commercial parathyroid extract on titrable acid, ammonia, and bicarbonate excretion in 9 subjects (mean SE).

The second major aspect of the surface chemistry of chromia-alumina that has to be considered is the acidic nature of its surface. The exact chemical nature of the acid sites of solid oxide catalysts such as alumina or silica-alumina has been a subject of considerable research and speculation for a number of years, yet despite these efforts a fully satisfactory chemical description of catalyst acidity has not been obtained. Nevertheless, in the case of chromia-alumina, there is good evidence for the existence of acid sites of one kind or another on the surface. Voltz and Weller (29), for example, studied the chemisorption of quinoline on chromia-alumina, with and without potassium promotion, and at the same time measured their titrable acidities in aqueous suspensions. Both methods indicated that chromia-alumina was acidic, and that the addition of potassium decreased the acidity. This observation was supported by the fact that the double bond isomerization of 1-pentene, normally an acid-catalyzed reaction, proceeded quite readily over pure chromia-alumina, but less readily over a chromia-alumina treated with potassium. 

In chronic hypercapnia, the full compensatory mechanism is placed in gear. The central events are increased acid secretion by the kidney (ammonium plus titrable acid) and increased reabsorption of bicarbonate (HCO3). Indeed, the maximum renal reabsorption of bicarbonate rises with the increase in Pco2 levels in blood. 

Cyanuric acid is a titrable weak acid (pffai — 6.88, pifa2 — H-40, pffas — 13.5) (10). The pH of a saturated aqueous solution of pure CA at room temperature is - 4.8. Thermodynamic properties of CA are given ia Table 1. Spectroscopic data are available (1 3). Proton nmr is of limited usefulness because of proton exchange and CA s symmetry and low solubiUty. Nuclear quadmpole resonance measurements ( " N) have been reported (12). 

Acetylation of kasuganobiosamine with acetic anhydride in methanol gave N,N -diacetylkasuganobiosamine which contained no titrable group and reduced 6.6 moles of sodium periodate, affording 4.7 moles of formic acid, 0.5 mole of carbon dioxide, and a reducing substance —i.e., N,N -diacetylkasugamine. 

Table 4.2 pK Values of Titrable Amino Acid Groups... 

To make sure that all fatty acids are indeed measured, the final titration is carried through to pH 9.0. A blank titration on the substrate emulsion is carried out to measure the amount of titrable material not due to lipase action. 

Actual compound formation also occurs between the dehydroascorhic acid and GSH reactants, though little attention has been paid to this condensation. Complexes of dehydroascorhic acid with one molecule of either GSH or thioglycolic acid were formed by Drake et al. (D19) in acetic acid solutions. Disappearance of iodine-titrable -SH groups and appearance of a new levorotatory material indicated the complex formation. This continued until an equilibrium was reached in about one hour at 0°C. At equilibrium more than half the dehydroascorhic acid was complexed. Remarkably little reduction of dehydroascorhic by the sulfhydryl compound occurred, since this reaction becomes significant only at neutral pH s. The complex is probably a thiosemiacetal, similar to... 

Acid as Energy Input for Model Protein with Titrable Functional Groups... 

Succinic acid is a dicarboxylic acid whose curve shows a break for each titrable hydrogen. What is interesting about that Well, the acidity constants in water for succinic acid are very close to each other, so that you cannot resolve two breaks in a titration curve. You are... 

The protonation constants of ligand 24 and 25 were determined by Arena and coll. [34], who reevaluated the literature pKa values of compound 24 [35] because they were not in agreement with solid state evidences [33]. Only two titrable protons were found in the pH region 2.5-11.0 and the proton formation constants determined (Log K = 3.34 and 11.5) rule out the existence of a "super acidic proton" (pKa < 1) for compound 24 [35]. However, this proton is much more acidic (5.3 log units) than the monomeric... 

Another well-characterized pH-sensitive liposome includes cholesterol hemisuccinate (CHEMS) as a stabilizer [97-100], and a carboxylated derivative of PE, A-succinyldioleoyl-PE, has been combined with DOPE to generate pH-sensitive liposomes [101]. pH-sensitive liposomes have been constructed using titrable double-chain glycerol-based amphiphiles as a PE vesicle stabilizer [102]. The pH-sensitive liposomes are stable at neutral or basic pH but are destabilized and become fusion competent at acidic pH. Eollowing the cellular uptake by an endocytic pathway, liposomes are exposed to a mildly acidic pH of endosomes, which is in the range of 5.0-6.5 [103,104]. 

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