Hydrogen Bonding in Organic Compounds. III. The Equilibrium Constant for the Dimerization of N-Methylmethane Sulphonamide

Abstract

During an investigation of the infrared spectra of organic sulphonamides and related compounds we made some observations of the spectrum of X-methylmethane sulphonamide in dilute carbon tetrachloride solution. The compound showed absorption bands at 3404 and 3300 cm-l which varied in relative intensity, when the concentration of the solution was changed, in a manner characteristic of a monomer-dimer equilibrium. The broader, lower frequency band that is characteristic of the dimer had a symmetrical contour, indicating that only a single species was involved. This we assume to have the formula (I).The sample of N-methylmethane sulphonamide was prepared in 80% yield by the condensation of methylamine with methane sulphonyl chloride in ether solution at 0 "C (Baxter, Cymerman-Craig, and Willis 1955). It was purified by distillation, b.p. 162 O C , at 15 mm. The hygroscopic substance was stored over phosphorus pentoxide for several weeks and then solutions were made up in spectroscopic grade carbon tetrachloride just before the spectra were recorded.The absorption bands were scanned with a Perkin Elmer 112, single-beam, double-pass, infrared spectrometer, fitted with a calcium fluoride prism, at the rate of 0 ~6 8 cm-l sec-l for the monomer band and 0 ~6 2 cm-l see-l for the dimer band. Allowance for convergence of the beam through the specimen was shown to introduce a correction of about 0.3%. The computed (cm-l) spectral slitwidths were 5 a 7 at 3400 cm-l and 5 a 1 a t 3300 cm-l. The integrated band areas were calculated by the " triangular slit function " method of Ramsay (1952) which assumes that the contour of the absorption band is a Lorentz curve. The measurements are summarized in Table 1.

Excess molar enthalpies of mixtures of pyrrolidin-2-one with methanol, or ethanol, or propan-1-ol, or butan-1-ol, or pentan-1-ol at the temperature 303.15K

“…The formula for the molar excess enthalpy H E m is: (4) where p* i , V* i , and V i are the characteristic pressure, volume, and reduced volume of the pure components. The f 2 represents the site fraction, V the reduced volume, and V E m is the excess molar volume of the mixture.…”

“…The various parameters of pure components have been taken from our previous publication. (7) The values of the interchange energy parameter X 12 were obtained by fitting the Flory formula, equation (4), to H E m at x = 0.5; therefore, X 12 = (6.89, 39.61, 57.71, 61.77, and 64.58) J·cm −3 for (pyrrolidin-2-one + alkanol).…”

“…Self-association in pyrrolidin-2-one is relatively strong, as shown by various studies. (1)(2)(3)(4)(5)(6) The basic C.O and acidic -NH groups of the peptide bond -NH-COlead to the self association of pyrrolidin-2-one in the pure liquid state. Recently, we reported (7) the excess molar volumes V E m and isentropic compressibilities of (pyrrolidin-2-one + alkanols) at T = 303.15 K.…”

Stereoelectronic structure and self-association of N-trimethylsilylsulfonamides RSO2NHSiMe3 (R = Me, CF3, Ph)

“…[1][2][3][4][5][6][7]. Similar to amides of carboxylic acids, sulfonamides are capable of formation of hydrogen bonds [8][9][10][11][12][13], both the oxygen and the nitrogen atoms being able to act as the center of basicity in these compounds. Thus, according to the data of NMR spectroscopy and quantum chemistry, the protonation at the nitrogen atom of the sulfonamide group is somewhat preferable than at the oxygen atom [9][10][11][14][15][16][17].…”

“…However, the oxygen atom can also be involved in the formation of a hydrogen bond, and its spectroscopic basicity has been measured by IR spectroscopy by evaluating the constants of complex formation with MeOH and p-FC 6 H 4 OH [18,19]. Similar to carboxamides, sulfonamides form heteroand self-associates [8,12,13,[20][21][22][23]. Self-association is most pronounced in the derivatives of trifluoromethanesulfonic acid, since the presence of trifluoromethyl substituent at the sulfur atom decreases the basicity of the sulfonyl oxygen and simultaneously substantially increases the acidity of the NH group [10,11,24,25].…”