The Influence of Hydration on Base Strength. I. General Theory for Amines

Condon, F. E.

doi:10.1021/ja00948a013

Cited by 28 publications

(8 citation statements)

References 3 publications

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“…The pK a value of the iminium ion H 2 C᎐ ᎐ NHPh ϩ will be lower 15,16 than that of the anilinium ion (pK a = 4.60). Hence at the pH values used in this study the unprotonated imine will be dominant.…”

Section: Mechanism Of Formation Of Anilinomethanesulfonatesmentioning

confidence: 95%

A mechanistic study of the reactions of formaldehyde with aniline in the presence of sulfite

Atherton

Brown

Crampton

2000

J. Chem. Soc., Perkin Trans. 2

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H NMR results are reported for the reactions of hydroxymethanesulfonate, 1, with aniline and its derivatives to produce anilinomethanesulfonates, 3. The mechanism of the reaction involves dissociation of 1 to produce formaldehyde, as a steady state intermediate, which reacts with aniline to give a carbinolamine; † subsequent dehydration and reaction with sulfite produces the product. The kinetics of individual steps have been investigated. The release of sulfite from 1, measured by reaction with iodine, is shown to involve the ionised, dianionic form when pH > 3. Rate constants, k 2 , and equilibrium constants, K 2 , are reported for carbinolamine formation; the values of k 2 , but not K 2 , are affected significantly by substituents in the aniline. It is deduced that the rate-limiting step in the overall formation of products 3 changes in the pH range 6-8 from carbinolamine formation to carbinolamine dehydration.Condensation reactions of the type shown in eqn. (1) are widelyused in synthesis. A well known example is the Mannich reaction 1 where HZ is a methylene compound with an acidic hydrogen. In the Strecker synthesis 2 of amino acids the first stage is the formation of an α-aminonitrile by reaction of a carbonyl compound with ammonia and cyanide. There is strong evidence for the intermediacy of imines or iminium ions in these reactions. 3-8 However the lifetimes of these species are expected to be very small in aqueous solution. 9-11Here we report a mechanistic study of reactions of the type shown in eqn. (1) where RNH 2 is aniline, or a substituted aniline, and HZ is hydrogen sulfite. It has been known for some time that sulfite, an excellent nucleophile for carbon, 12 may participate in such reactions to yield N-methylsulfonates. However the only previous mechanistic study is a brief report 13 of the kinetics of the reactions using ammonia as the amine. Results and discussionIt was convenient to use the sodium salt of hydroxymethanesulfonate, 1, which is a crystalline material, as the source of formaldehyde. 1 H NMR measurements were made in deuterium oxide. Spectra obtained with 1 and aniline, 2, in a 1 : 1 molar ratio showed the gradual disappearance of bands due to reactants and the appearance of new bands attributed to the adduct 3, as shown in eqn. (2). The change, which took several hours, went to virtual completion. Bands due to the adduct, 3, were close to, but distinct from, those of the reactants. Chemical shifts for reactions with aniline (2, R = H) and(2) † The IUPAC name for carbinolamine is aminomethanol.

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Section: Mechanism Of Formation Of Anilinomethanesulfonatesmentioning

confidence: 95%

A mechanistic study of the reactions of formaldehyde with aniline in the presence of sulfite

Atherton

Brown

Crampton

2000

J. Chem. Soc., Perkin Trans. 2

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“…When it was supposed that the strong base cause large effect on the increase of oxidation rate of the passivated surface, we cannot explain that trimethylamine which is the particularly weakest base among amines above, has the larger effect than propylamine and butylamine have. It is wellknown that small pK b of tertiary amines is due that these molecules need more water molecules than primary amines does in solvation by water molecules in the proton dissociation [26]. The pK b is of course deeply related to I-effect of alkyl group in amine molecules.…”

Section: B Oxidation Rate Of Hydrogen-terminated Si(100) In Water Somentioning

confidence: 99%

ToF-SIMS analysis of influence of alkylamine compounds in UPW on hydrogen-terminated Si surface

Kobayashi

Owari

2006

e-J. Surf. Sci. Nanotechnol.

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Adsorption behaviors of alkylamine compounds in UPW (ultra pure water) on hydrogen-terminated Si(100) were elucidated mainly by ToF-SIMS. Si wafers cleaned by heat treatment in 500• C were etched in 0.38% HF and soaked in water solution of alkylamine after 1 min UPW rinse. The peak intensity of amine molecular ions and SiH/Si ratio detected by ToF-SIMS are considered to be used as a measure of quantity of adsorbed molecules and surface oxidation, respectively. It was found that hydrophobic amine molecules with longer CH 2 chain tend to be left with high concentration in a very short time of soaking and also tend to have the larger effect on the increase of surface oxidation of hydrogen-terminated surface. The latter phenomenon was explained by an I-effect of alkyl group.

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“…The search for structure-reactivity relationships for the ionization of amines in water has a long history (1)(2)(3)(4)(5)(6)(7)(8). The simple approach, based on a comparison of pKa values, led to the wellknown amine anomaly (9,10) where R2NH > R3N > RNH2, an order contrary to normal expectations based on inductive effects.…”

Section: Introductionmentioning

confidence: 99%

“…The simple approach, based on a comparison of pKa values, led to the wellknown amine anomaly (9,10) where R2NH > R3N > RNH2, an order contrary to normal expectations based on inductive effects. It was subsequently found that the expected order was followed in the gas phase (1 [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and hence the anomaly could not be attributed to steric effects (15,16) or to other internal factors (17) but rather mas associated with solvation.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic parameters for the basic ionization of some cyclic amines in water

Lobo¹,

Murty²,

Robertson³

1976

Can. J. Chem.

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SHEILA TERESA LOBO, TANIKELLA S. S. R. MURTY, and Ross ELMORE ROBERTSON. Can. J. Chem. 54, 3607 (1976).The thermodynamic parameters defining the basic dissociation in water of diethylamine, cyclohexylamine, piperidine, and quinuclidine have been determined by a dilution method based on conductance measurements. 54, 3607 (1976).Les paramktres thermodynan~iques dkfinissant la dissociation basique, dans l'eau. de la diethylamine, de la cyclohexylamine, de la pipCridine et de la quinuclidine ont Ct C determinis par une mkthode de dilution basCe sur des mesures de conductivitCs. A 25 ^C, les valeurs de ASaO et de ACPa0 pour l'ionisation acide des ions ammonium correspondants sont ASaO -8.08, -1.24, -8.51, -13.65 cal deg-I molkl et ACPa0 13.9, -2.7, 18.0, 4.2 cal deg-1 mol-1. On discute de la relation entre ces valeurs dCriv6es et les changements dans la solvation: on note les valeurs apparemment anormales du ACDaO de la cyclohexylan~ine et de la quinuclidine mais on ne peut les rationaliser.[Traduit par le journal] Introduction In this paper we report the thermodynamic quantities defining the ionization of certain cyclic amines in water and note the relationship between these quantities and structure.The search for structure-reactivity relationships for the ionization of amines in water has a long history (1-8). The simple approach, based on a comparison of pKa values, led to the well-

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The Influence of Hydration on Base Strength. I. General Theory for Amines

Cited by 28 publications

References 3 publications

A mechanistic study of the reactions of formaldehyde with aniline in the presence of sulfite

A mechanistic study of the reactions of formaldehyde with aniline in the presence of sulfite

ToF-SIMS analysis of influence of alkylamine compounds in UPW on hydrogen-terminated Si surface

Thermodynamic parameters for the basic ionization of some cyclic amines in water

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