Electric Polarization of Carboxylic Acids. III. A Study of the Association of Some Additional Carboxylic Acids in Benzene Solution

Abstract

ASSOCIATION OF CARBOXYLIC ACIDS IN BENZENE SOLUTION 1Gil the non-ionic mechanism than for the ionic mechanism. It is apparent that the evidence for the ionic nature of this and similar reactions needs careful re-examination.Acknowledgment.-The authors wish to express their appreciation for the help of Miss S. Amende and Miss F. Tibbetts in obtaining the data for this paper. Summary The rates of formation of NH2C1, CHaNHCl and (CH3)2NCI from HOCl and the appropriate amine have been studied in dilute aqueous solution under a variety of experimental conditions. The reactions are second order with respect to concentrations of the reactants, but the rates show a marked dependence on the PH of the solution.The observed variations in rates with PH can be quantitatively accounted for by considering that reaction occurs either between HOCl and NHa, CHsNHz or (CH&NH, or between OC1and NH4+, CH3NH3+ or (CH&NHz+. It has been shown mathematically that for reactions of this type, between weakly ionized substances, it is impossible to distinguish kinetically between the mechanism which assumes ions to be the reactants and that which assumes molecules to be the reactants. On this basis the validity of the evidence for the ionic nature of the ammonium cyanate reaction has been questioned.Evidence has been presented which indicates that the molecular mechanism is more probable for the formation of the chloramines. On this basis the rates of the reactions can be expressed by the equations d[NH&l]/dt = 2.5 X lO1%-25O0/RT [NHs] [HOCI] d [CHaNHC1]/dt = 6.0 X lO1*e-450o/R~[CHaNHr] [HOCI] d[(CH8)aNCl]/dt = 1.2 X 1011e-800/RT[(CH*)eNH] [HOCI] CAMBRIDGE, MASSACHUSETTS SEPWMBER 29, 1948 [CONTRIBUTION FROM THEThe association of carboxylic acids in hydrocarbon and certain other organic solvents as well as in the vapor phase has been the subject of numerous investigations by a variety of methods. With regard to association in solution, however, relatively few reliable quantitative data are available. Exceptions are the isopiestic measurements of Wall and c o -w~r k e r s~,~ on benzoic acid and several other non-volatile acids in benzene. Although the more generally applicable methods involving distribution between water and an immiscible organic solvent has been used on occasion, this procedure is open to question because of the effect of the finite solubility of the water on the association equilibrium in the second medium.6t6In earlier papers from this Laboratory,'~~ it was shown that measurements of the dielectric constants of very dilute solutions of carboxylic acids in the non-polar solvents, benzene and heptane, could be used to study the association of these acids. Assuming that only monomeric and dimeric forms were present a t these low concen-(1) The contents of this paper were presented at the St. Louis (2) Ethyl Dow Post-Doctorate fellow, 1941. Present address: (3) F. H. A. Pohl, M. E. Ilobbs and P. M. Gross, J . Chcm. Phys., 9, 408 (1941). (8) A. A. Maryott, M. E. Hobbs and P. M. Grosr, ibid.. 9, 415 (1941). meetiug of the Ameri...

Solubilities of Stearic Acid in Organic Solvents and in Azeotropic Solvent Mixtures

“…12,13 A log plot of the solute solubility as mole fraction in pure solvents versus 1/T should be linear. The corresponding plot is shown in Figure 2.…”

“…4 When the calculations were made, a value of 61.209 kJ · mol -1 was used for the fusion enthalpy of stearic acid. 12 All solvents (Panreac, analytical grade) were dried over 4 Å molecular sieves. The purity, checked by GC, was higher than 0.999 mass fraction.…”

“…UNIQUAC a 12 , b 12 , ln (13) In this equation (14) where X m is the mole fraction of group m. The group interaction parameter Ψ mn is given by…”

Reliable and Safe, Gram-Scale Hydrogenation and Hydrogenolysis of O-Benzyl Ether Groups with In Situ Pd0/C Catalyst

“…Yield: 14.5 g (97%); white solid; mp 46°C (Lit. 13 46.4-46.8°C); HPLC (MeCN-H 2 O, 70:30): t R = 3.42 min. 1 H NMR (CDCl 3 , 300 MHz): d = 2.72 (dd, J = 7.0, 8.1 Hz, 2 H), 2.99 (t, J = 7.5 Hz, 2 H), 7.23-7.36 (m, 5 H), 11.0 (br s, 1 H).…”

On the microstructure of organic solutions of mono-carboxylic acids: Combined study by infrared spectroscopy, small-angle neutron scattering and molecular dynamics simulations

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