Organic compounds acid constants

Table 22.1 Acidity Constants for Some Organic Compounds...

An acidity list covering more than 5000 organic compounds has been published E.I . Serjeant and B. Dempsey (eds.), "Ionization Constants ol Organic Acids in Aqueous Solution." IUPAC Chemical Data Series No. 23, Pergamon Press, Oxford, 1979. 

Appendix A Nomenclature of Polyfunctional Organic Compounds A-1 Appendix B Acidity Constants for Some Organic Compounds A-8 Appendix C Glossary A-10 Appendix D Answers to In-Text Problems A-30... 

Compounds with an acidity constant, pK, in the range of 4 to 10, i.e. weak organic acids or bases, are present in two species forms at ambient pH. This pA a.i. range includes aromatic alcohols and thiols, carboxylic acids, aromatic amines and heterocyclic amines [15]. Conversely, alkyl-H and saturated alcohols do not undergo protonation/deprotonation in water (pA iw 14). 

Quench elbow and secondary scrubber. This system is used to remove acid gases formed from the catalytic oxidation of halogenated organic compounds. The operation of the secondary scrubber is identical to that of the primary scrubber with the exception of a recirculation cooler that maintains scrubber exit gas temperature at 120°F. The secondary scrubber has a constant liquid blowdown that is collected in holding tanks and tested for agent prior to release. 

Table 1.5 represents acidity constants of organic compounds (AH) and their cation-radicals (AH+ ) calculated for their solutions in DMSO (a very polar solvent) at 25°C. 

In a sediment system, the hydrolysis rate constant of an organic contaminant is affected by its retention and release with the sohd phase. Wolfe (1989) proposed the hydrolysis mechanism shown in Fig. 13.4, where P is the organic compound, S is the sediment, P S is the compound in the sorbed phase, k and k" are the sorption and desorption rate constants, respectively, and k and k are the hydrolysis rate constants. In this proposed model, sorption of the compound to the sediment organic carbon is by a hydrophobic mechanism, described by a partition coefficient. The organic matrix can be a reactive or nonreactive sink, as a function of the hydrolytic process. Laboratory studies of kinetics (e.g., Macalady and Wolfe 1983, 1985 Burkhard and Guth 1981), using different organic compounds, show that hydrolysis is retarded in the sohd-associated phase, while alkaline and neutral hydrolysis is unaffected and acid hydrolysis is accelerated. 

As indicated earlier (Section 3.1.1) the sorption of organic compounds onto dissolved matter can significantly increase the solubility of the compound. This can in turn affect the fate of these chemicals in the environment. We can use physicochemical parameters such as distribution coefficients (log D), aqueous acid dissociation constants (pAia), and octanol-water partition coefficients (p/to )-These attributes are also linked to the acidity and alkalinity of the environment as well as lipohilicity of the compound. The mathematical relationships between these attributes are outlined below to explore how each of these impacts the fate of PPCPs in the environment. 

Production of phenol and acetone is based on liquid-phase oxidation of isopropylbenzene. Synthetic fatty acids and fatty alcohols for producing surfactants, terephthalic, adipic, and acetic acids used in producing synthetic and artificial fibers, a variety of solvents for the petroleum and coatings industries—these and other important products are obtained by liquid-phase oxidation of organic compounds. Oxidation processes comprise many parallel and sequential macroscopic and unit (or very simple) stages. The active centers in oxidative chain reactions are various free radicals, differing in structure and in reactivity, so that the nomenclature of these labile particles is constantly changing as oxidation processes are clarified by the appearance in the reaction zone of products which are also involved in the complex mechanism of these chemical conversions. 

Alfassi, Z. B S. Padmaja, P. Neta, and R. E. Huie, Rate Constants for Reactions of NO, Radicals with Organic Compounds in Water and Acetonitrile, J. Phys. Chem., 97, 3780-3782 (1993). Allen, H. C., J. M. Laux, R. Vogt, B. J. Finlayson-Pitts, and J. C. Hemminger, Water-Induced Reorganization of Ultrathin Nitrate Films on NaCI—Implications for the Tropospheric Chemistry of Sea Salt Particles, J. Phys. Chem., 100, 6371-6375 (1996). Allen, H. C., D. E. Gragson, and G. L. Richmond, Molecular Structure and Adsorption of Dimethyl Sulfoxide at the Surface of Aqueous Solutions, J. Phys. Chem. B, 103, 660-666 (1999). Anthony, S. E R. T. Tisdale, R. S. Disselkamp, and M. A. Tolbert, FTIR Studies of Low Temperature Sulfuric Acid Aerosols, Geophys. Res. Lett., 22, 1105-1108 (1995). 

High temperature and supercritical H2O have greatly enhanced acidity (and basicity) compared to room-temperature water because the dissociation constant increases as water is heated towards the critical point [25,27], At the same time, there is a marked drop in the dielectric constant which reduces the solubility of polar compounds but increases the solubility of non-polar compounds, and of organic compounds in particular. 

FORMAMIDE. Form amide (meibanamide), HCONHi. is the lirsi member of the primary amide series and is the only one liquid at room temperature. II is hygroscopic and has a faint odor of ammonia. Formamide is a colorless to pale yellowish liquid, freely miscible with water, lower alcohols and glycols, and lower esters and acetone. It is virtually immiscible in almost all aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, and ethers. By virtue of its high dielectric constant, close to that of water and unusual for an organic compound, formamide has a high solvent capacity lor many heavy-metal salts and for salts of alkali and alkalinc-carth metals. It is an important solvent, in particular for resins and plasticizers. As a chemical intermediate, formamide is especially useful in the synthesis of heterocyclic compounds, pharmaceuticals, crop protection agents, pesticides, and for the manufacture of hydrocyanic acid. 

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