DichlorOacetic acid properties

Dichloroacetic acid [79-43-6] (CI2CHCOOH), mol wt 128.94, C2H2CI2O2, is a reactive intermediate in organic synthesis. Physical properties are mp 13.9°C, bp 194°C, density 1.5634 g/mL, and refractive index 1.4658, both at 20°C. The Hquid is totally miscible in water, ethyl alcohol, and ether. Dichloroacetic acid K = 5.14 X 10 ) is a stronger acid than chloroacetic acid. Most chemical reactions are similar to those of chloroacetic acid, although both chlorine... 

Unfractionated poly(a-phenylethyl isocyanide), [ ]tS°c = 0.41 dl/g, A n = 30000, also displays a similar decay in dichloroacetic acid at 30° C, where rjt of a 1.16% solution decreases from 1.515 to 1.165 in 5 days (19). This polymer, therefore, shows common properties in regular solutions, in which it has been... 

Use of the optically resolved complex leads to the optically active polymer, but this property, which arises from the helical chain structure, is found only in the swollen polymer and is easily lost in toluene or dichloroacetic acid solution 144). The polymerization occurs with a high degree of enantioface selection, and the model for the product backbone is indeed chiral. However, because of the presence of a mirror, plane in the polymer chain (effects of chain termini neglected), the product does not have chiral properties in solution. 

Polyhaloacetic acids and their partially hydrodehalogenated products represent a second important family of herbicide-/pesticide-derived substrates. In their review on the environmental applications of industrial electrochemistry, Juttner and co-authors (Juttner et al. 2000) documented the electroreductive dechlorination of dichloroacetic acid (a by-product of monochloroacetic acid), a way to recover the valuable compound and avoid wastes. The electrochemical reduction of polychloro- and polybromo-derivatives was performed by Korshin and Jensen (2001) on Cu and Au cathodes. Complete dehalogenation was obtained for all substrates, but for monochloroacetic acid. To overcome the intrinsic poor reactivity of the monochloro-derivative the photoelectrochemical properties of a p-doped SiC electrode were investigated (Schnabel et al. 2001) however, the dehalogenation stopped at monochloroacetic acid. 

The haloacetic acids (HAA) are comprised of mono-, di- and trichloroacetic acid, mono-, di-, and tribromoacetic acid, and bromo-chloroacetic acid, bromo-dichloroacetic acid, and dibromo-chloroacetic acid. Toxicological studies showed that these compounds have carcinogenic properties and may have adverse reproductive consequences. HAA have no strong chromophore for sensitive UV detection electrochemical detection has been described. Analysis by GC-MS requires derivatization. Due to their relatively low molecular mass, the LC-MS analysis can be hindered by low-mass background interferences. 

The observation that albumin is soluble in acid alcohol and acid acetone seems to have remained unrecognized for more than 20 years (Cll, L18) until it was rediscovered in 1954 by Delaville et al. (D7, D8). Improved methods on a microscale, based on this property, have been devised (D5, D7, D8, W8). The phenomenon under discussion is probably due to the formation of the imexpanded F form of albumin at a pH between 3 and 4 when COOH ionization is repressed and hydrophobic surfaces of the molecule are exposed (F15). At this pH, a solvent of appropriate dielectric constant (DC) is required for solubilization 1 ml methanolic solution (DC 33) containing 0.1 ml water and 0.1 g TCA will dissolve 30 mg albumin similar ethanolic (DC 25) acetone (DC 21) and ether (DC 4) solutions will dissolve 3, 1, and 0.1 mg albumin, respectively. Other solvents and acids have been employed, e.g., dichloroacetic acid-acetone (Rl), dichloroacetic acid-ethylene dichloride (Yl), and hydrochloric acid-methanol (M20). With the use of phosphate buffer, pH 2.4, and ethanol (P6), albumin may be extracted quantitatively from liver ribosomes. 

Our present knowledge of the helix-coil transition in synthetic polypeptides, with particular reference to the poly-y-benzyl-h-glutamate-dichloroacetic acid-1,2-dichloroethane system, is briefly reviewed. Recent results concerning the effect of solvent composition and of polypeptide and solvent deuteration on the thermodynamic properties of the transition show that both the thermodynamics and presumably the molecular mechanism of the transition are generally more complicated than had been previously supposed. 

Hanlon (1966) has presented spectra for poly-y-benzyl-L-glutamate in systems of varying solvent composition of dichloroacetic acid and ethylene dichloride. The 1.51 /i band indicates protonation of the peptide residues. Poly-y-benzyl-L-glutamate exhibits a unique protonation pattern characterized by two transition regions one at low concentrations of acid, and the other between concentrations of 75 % and 80% acid only the latter transition can be reversed by an increase in temperature within the range 11 to 55 C. This unique protonation pattern parallels that found with measurements of other physical properties of poly-y-benzyl-L-glutamate in this solvent system. 

Mullen and coworkers have also prepared the blue-emitting (A, iax = 450 nm) polyketal 149, films of which can be converted by exposure to dichloroacetic acid vapour to the orange-emitting (A,max = 580 nm) polyflu-orenone 150 (Scheme 71) [249]. The carbonyl groups enhance the electron-accepting properties of 150, and this polymer shows useful electrontransporting properties, though the acidic residues from the conversion are a potential source of problems for electronic applications [250]. 

High amylose starch, treated with formamide and dichloroacetic acid and a plasticizer yield homogenous, flowable quasi-solutions without formation of gels when they are heated, with stirring, to temperatures above 80°C. As plasticizers serve ethylene glycol, triethylene glycol, poly(vinyl alcohol), and glycerol (13). The properties of such prepared compositions are shown in Table 7.4. 

Most work has been concentrated on the formation, structure and properties of ternary systems composed of one cellulose derivative and mixed solvents or other polymer blended solutions. Thus, the liquid crystal properties of ethylcellulose/acrylic acid, ethylcellulose/dichloroacetic acid and ethylcellulose/glacial acetic acid solutions were studied, observing the mesophase behavior when their concentrations exceeded 0.6, 0.3, and 0.35 g/ml, respectively, at room temperature [143]. Also,... 

An example of the determination of the optical shear coefficients An/Ax (FBF method) for samples and fractions of an aromatic polyether (PE, polymer 6 in Table 3.11) in dichloroacetic acid is shown in Fig. 3.22. Figure 3.22 shows that the values of An/(Ax) for PE [102] (there are similar data for P-IO-MTOC [101, 103]) are essentially dependent on the molecular weight of the polymer. This means that the molecules of these polymers exhibit optical properties characteristic of rigid-chain polymers [10]. The experimental dependence of Art/(At) = [n]/[T]] on M can be used for estimating the equilibrium rigidity of the macromolecules from the optical data [7,108]. The experimental data shown in Fig. 3.22 are compared with the theoretical dependence [Eqs. (6)-(8)] for polymer PE [108]. The optical characteristics of the low-molecular-weight frag-... 

TABLE 3.11. Optical and Electrooptical Properties of Macromolecules with Mesogenic Groups in the Main Chain in Dichloroacetic Acid... 

The presence of a cholesteric helicoid stracture determines the significant optical rotation of HPC in aqueous solutions p is 4 10 degml/dm-g [10]. Analysis of the optical properties indicates the formation of a left-handed cholesteric helix in aqueous solutions of HPC, solutions of cellulose carbanilate in methyl ethyl ketone, and ethylcellulose in dichloroacetic acid. In most cases. 

Dichloroacetic Acid 50 75 9 Resistant little or no change in weight small effect on mechanical properties generally suitable for practical use Fluorosint Quadrant EPP... 

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