Propionic acid, dissociation constant

Distorted octahedral structures have been proposed for the 1 1 neutral complexes formed between bivalent transition-metal ions and hydroxymethyl-phosphonic acid, H0CH2P03H2. A series of new dialkylaminomethylenedi-phosphonic acids (H0)2P(0)CH(NR R )2P(0)(0H)2 has been prepared from phosphorus trihalides and NN-dialkylformamides. Acid dissociation constants and the complex behaviour toward Cu " for the phosphinyl-propionic acid Ph(H0)P(0)CMe(0H)(C02H) have been evaluated. ... 

Fig. 19.7. Relationship between acid dissociation constant pK and frequency (v) of the antisymmetric stretching vibration of salts of carboxylic acids in DjO solution. 1, Trifluoroacetic 2, trichloroacetic 3, dichloroacetic 4, cyanoacetic 5, chloroacetic 6, 2-phenoxypropionic 7, methoxyacetic 8, formic 9, glycollic 10, lactic 11, 3-hydroxybutyric 12, acetic 13, propionic 14,cyclohexane carboxylic 15, polyacrylic 16, malonic 17, phthalic 18, benzoic 19, salicylic and 20. polyguluronic. polygalacturonic, galacturonic, alginic, hyaluronic, and chondroitin sulfates A, B, and C. ( C) From Goulden and Scott, 1968 (O) from Chapman et at. 1964. The pK values are from references given in Goulden and Scott (1968). (Goulden and Scott, 1968.)...

Lactic acid, CH3CH(OH)COOH, received its name because it is present in sour milk as a product of bacterial action. It is also responsible for the soreness in muscles after vigorous exercise, (a) The pfQ, of lactic acid is 3.85. Compare this with the value for propionic acid (CH3CH2COOH, pfC = 4.89), and explain the difference. (b) Calculate the lactate ion concentration in a 0.050 M solution of lactic acid, (c) When a solution of sodium lactate, (CH3CH(OH)COO)Na, is mixed with an aqueous copper(II) solution, it is possible to obtain a solid salt of copper(II) lactate as a blue-green hydrate, (CH3CH(0H)C00)2 Cu-a H20- Elemental analysis of the solid tells us that the solid is 22.9% Cu and 26.0% C by mass. What is the value for x in the formula for the hydrate (d) The acid-dissociation constant for the Cu (aq) ion is 1.0 X 10. Based on this value and the acid-dissociation constant of lactic add, predict whether a solution of copper(Il) lactate will he addic, basic, or neutral. Explain your answer. 

Nicotinic acid has a molecular weight of 123.ii. From water or alcohol it crystallizes in white, odorless needles with a tart taste. It melts at 236.6° (234-237° as cited in referenceio) and sublimes without decomposition. In aqueous solution it has an absorption maximum in the ultraviolet region at 261.5 mfi. The molecular extinction coefficient at this point ispH-dependent, decreasing with increase in pH from 1.28 to 13.0. By two methods involving successive approximations K., the thermodynamic acid dissociation constant, was found to be 1.12- nd 1.23-10 , while Kt, the basic dissociation constant was 3.55-I0 H by both methods (22°). At 25°, Ostwaldi found the acid dissociation constant to be 1.4-10 , that is between propionic and butyric acids. Nicotinic acid is not in amphoteric ion form in solution . 

Fig. 8. Selected examples of aromatic donor molecules that form complexes with HRP C. The apparent dissociation constant for complex formation with the resting state plant enzyme is given (original references should be consulted for details of solution conditions and error estimations). (1) 2-Naphthohydroxamic acid (228) (2) benzhydroxamic acid (228) (3) 2-hydroxybenzhydroxamic acid (salicyUiydroxamic acid) (228) (4) benzhy-drazide (228) (5) cyclohexylhydroxamic acid (228) (6) 4-methylphenol (p-cresol) (192) (7) 2-methoxyphenol(guaiacol) (192) (8) indole-3-propionic acid(24i) (9)p-coumaric acid (238) (10) aniline (243).

The dissociation constants of acetic, propionic and butyric acid in aqueous solution are comparable (pK values of 4.75, 4.87 and 4.81, respectively). The stability of the acyl cations increases in the order ... 

Hamed HS and Ehlers RW, The dissociation constant of propionic acid from 0 to 60°, ACS, 55,2379-83 (1933). NB Used hydrogen electrodes in cells widiout liquid junction potentials. Solutions were prepared with carbonate-free sodium hydroxide. The effects of ionic strength from added KCl extrapolated to / = 0.00. 

High pressure increases the ionization of weak electrolytes, by enhancing the solvation of the ions, but the effect is not very great. At 25°C and 3000 atmospheres, pATa values are decreased as follows formic acid, by 0.38, acetic acid, by 0.50, and propionic acid, by 0.55 (Hamann and Strauss, 1955). The logarithm of the basic dissociation constant of ammonia (into ammonium ion and hydroxyl ion) is increased by 1.14 for a pressure increase of 3000 atmospheres (Buchanan and Hamann, 1953) and by 2.72 for a pressure... 

The next problem lies in the determination of interrelations between the concentrations of individual species. With this aim, the results of analysis performed in Section 3.4.2 could be applied to the present problem. They show that the image of ideally labile system seems to be acceptable, when the rate constants for LH2 or LH dissociation are sufficiently high. The lower limit of k could be estimated at 10 s (steady-state conditions) for linear potential sweep conditions, this limit is supposed to be one to two orders higher. According to the data obtained with hydrodynamic modified rotating disc electrode (RDE) [1], the k - values for formic, acetic, and propionic acids are 4.83 X10, 3.46 X10 , and 2.88 X10 s respectively, but polarographic measurements produce one order lower quantities [2]. Anyway, these acids and similar acids could be treated as sufficiently labile. 

The dissociation constants of amino acids can be determined, for example, by titration of the acid. Figure 1.2 shows titration curves for glycine, histidine and aspartic acid. Table 1.2 lists the dissociation constants for some amino acids. In amino acids the acidity of the carboxyl group is higher and the basicity of the amino group lower than in the corresponding carboxylic acids and amines (cf. pK values for propionic acid, 2-propylamine and alanine). As illustrated by the comparison of pK values of 2-aminopropionic acid (alanine) and 3-aminopropionic acid ( 3-alanine), the pK is influenced by the distance between the two functional groups. 

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