Isobutyric acid/water

The specific rates of hydrolysis of five organic halides in three water-based liquid mixtures near their respective equilibrium consolute points have been observed to be suppressed. The systems studied included t-amyl chloride in isobutyric acid water (upper consolute temperature), and 3-chloro-3-methylpentane in 2-butoxyethanol water (lower consolute temperature). The slowing effect occurred within a few tenths of a degree on either side of the consolute temperature. 

Greer has made careful new measurements of the coexistence curve of isobutyric acid + water and has reanalysed earlier measurements on the system CS2 + CHgNOa. She concludes that the volume fraction is the preferred composition variable, that the limiting values of jS are appreciably lower (P = 0.324 0.018 for the first system and j8 = 0.316 0.008 for the second) than previously believed, and that the behaviour further from is consistent with extended scaling . ... 

Dobashi et al. [44] found that the data of Figure 9-23 also follow eq 4.4 with / = 0.332 0.001 independent of molecular weight. Figure 9-24 illustrates this fact for three different My,. We see that the range of e in which eq 4.4 holds diminishes with increasing molecular weight. Thus, for the case i, it is restricted to Tc—T < 0.7°C. Dobashi et al. s j3 is consistent with 0.327 0.004 previously obtained by Nakata et al. [45] for a polystyrene with Mw = 1560 x 10 in cyclohexane and also with 0.326 0.003 for methanol + cyclohexane (e < 0.06), 0.328 0.007 for aniline + cyclohexane (e < 0.03), and 0.328 0.004 for isobutyric acid + water (e < 0.006). Dobashi et al. thus concluded that the system polystyrene + methylcyclohexane belongs to the same universality class as binary mixtures of ordinary simple liquids. 

Fig. 10-9. Reduced peak position (/m as a function of the reduced time r for VSCQ of the system isobutyric acid + water [17]. KO stands for the theory of Kawasaki and Ohta[18]. Data points are for the indicated values of AT =... 

ANOMALOUS SHEAR VISCOSITY OF THE ISOBUTYRIC ACID-WATER SYSTEM NEAR THE CRITICAL POINT. 

NOR Norman, A.I., Manvilla, B.A., Frank, E.L., Niamke, J.N., Smith, G.D., and Greer, S.C., Partitioning of poly(ethylene oxide), poly(ethylenimine), and bovine serum albumin in isobutyric acid + water, Macromolecules, 41, 997, 2008. 

RE2 Reddy, P.M., Venkatesu, P., and Bohidar, H.B., Influence of polymer molecular weight and concentration on coexistence curve of isobutyric acid + water, J. Phys. Chem. B, 115, 12065, 2011. 

Chou, Y.C., and Goldburg, W.I. (1979) Phase separation and coalescence in critically quenched isobutyric acid-water and 2,6-lutidine-water mixtures, Phys. Rev. A 20, 2105. 

Wong, N.-C., and Knobler, C.M. (1978) Light scattering study of phase separation in isobutyric acid + water mixtures, J.Chem.Phys. 69, 725. 

Effective susceptibility exponent as a function of logr for xenon, liquid mixtures of 3-methylpentane + nitroethane (3MPNE), isobutyric acid + water (IBAW), and of tetra-n-butyl ammonium picrate+1,4-butanediol/l-dodecanol (TPDB). 0,0, , x. A, + and, indicate... 

W. Fenzl, Scaling properties of the surface tension of isobutyric-acid-water mixtures, Europhys. Lett. 24 (1993) 557-562. 

In industrial practice, the identification of amino acids may be important, for example, for the detection of substances of protein character in some industrial products (glue, for example). According to our experience, this is best carried out by paper chromatographically detecting the presence of amino acids in their acid (HCl) hydrolyzates. The same operations should be carried out with standard, authentic samples. The following solvent systems should serve as well-established practical examples phenol saturated with water w-cresol-water (1 1) containing traces of cupron (a-benzoinoxime) and with 0.1% ammonia in the atmosphere isobutyric acid-water (4 1) amyl alcohol-pyridine-water (35 35 30) sec-butanol- 3%... 

Isobutyric acid, dimethylacetic acid, 2-methylpropanoic acid, (CHjjjCH COOH, colourless syrupy liquid with an unpleasant odour b.p. 154°C. Prepared by oxidation of 2-methylpropanol with K2Cr207 and H2SO4. Salts soluble in water. Used in alkaline solution for sweetening gasoline. 

The monoisobutyrate ester of TMPD, Texanol, or Filmer IBT, formally an isobutyraldehyde trimer, is prepared in a single step from isobutyraldehyde or, alternatively, by the esterification of TMPD with isobutyric acid. This monoester is most commonly employed as a coalescing agent for latex-based paints and water-based ink formulations. 

Mevalonic acid 5-phosphate [1189-94-2] M 228.1, pKes,(d 1.5 (PO4H2), pKEst(2) 4.4 (CO2H), pKEst(3) (P04H ). Purified by conversion to the tricyclohexylammonium salt (m 154-156°) by treatment with cyclohexylamine. Crystd from water/acetone at -15°. Alternatively, the phosphate was chromatographed by ion-exchange or paper (Whatman No 1) in a system isobutyric acid/ammonia/water (66 3 30 Rp 0.42). Stored as the cyclohexylammonium salt. 

A mixture of 22 grams of Oi-(p-chlorophenoxy)isobutyric acid, 3.8 grams of 1,3-propane-dioi, 0.5 gram of p-toiuenesulfonic acid and 150 ml of xylene was refluxed. When the theoretically calculated amount of water had been removed, the xylene solution was washed with dilute aqueous sodium bicarbonate and then the xylene was distilled off. The residue was distilled under reduced pressure to give 11 grams (47% yield) of 1,3-propanediol bis[a-(p-chlorophenoxy)isobutyrate] boiling at 197° to 200°C/0.03 mm Hg. 

Kemp and Waters found a primary kinetic isotope effect of 8.7 for oxidation of C-deuterated mandelic acid and noted a large difference in rate between the oxidations of mandelic acid k at 24.4 °C = 1.7 l.mole . sec ) and a-hydroxy-isobutyric acid ( 2 at 24.4 °C = 5.6 x 10 l.mole . sec ) — a difference not reproduced for the oxidation of these compounds by the one-equivalent reagent, manganic sulphate. The various data are fully in accord with a Westheimer-type mechanism, viz. 

A modified nucleotide found in RNA sequencing could either be a new nucleotide of unknown chemical structure or it could correspond to an already known modified nucleotide (up to now about 90 different modified nucleotides have been identified in RNA). Keith [124] proposed preparative purifications of major and modified ribonucleotides on cellulose plates, allowing for their further analysis by UV or mass spectrometry. Separation was realized by two-dimensional elution using the following mobile phases (1) isobutyric acid-25% ammonia-water (50 1.1 28.9,... 

Carboxylic acids can also be formed by a reaction of small alkanes, carbon monoxide, and water on solid acid catalysts (93,94). By in situ C MAS NMR spectroscopy (93), the activation of propane and isobutane on acidic zeolite HZSM-5 was investigated in the presence of carbon monoxide and water. Propane was converted to isobutyric acid at 373 73 K, while isobutane was transformed into pivalic acid with a simultaneous production of hydrogen. On SZA, methyl isopropyl ketone was observed as evidence for the carbonylation of isobutane with carbon monoxide after the sample was held at 343 K for 1 h (94). When the reaction of isobutane and carbon monoxide was carried out in the presence of water, pivalic acid was identified as the main reaction product (94). These observations are rationalized by the existence of a small number of sites capable of generating carbenium ions, which can be further trapped by carbon monoxide (93). 

ISOBUTYRIC ACID (Table IV) Deuterium oxide Methylene iodide Water... 

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