The Heat Capacity, Entropy and Heat Content of Sodium Amide from 15 to 300°K. The Thermodynamics of Amide Ion in Liquid Ammonia<sup>1</sup>

Coulter, Lowell V.; Sinclair, John; Cole, Arthur G.; Roper, Gerald C.

doi:10.1021/ja01521a017

Cited by 27 publications

(22 citation statements)

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“…Because catalytic reactions of the meta -substituted, electron-poor aryl halides occur in much lower yields than those of the para -substituted analogs, it appears that the rates of the transmetalation and reductive elimination portion of the catalytic cycle are affected strongly by the relative electron-withdrawing ability of the aryl group in the meta - or para -position. Because the pKa values of ammonia and monohydrogen phosphate are so different (33 for ammonia64 and 12 for HPO 4 2-65 respectively), we assume that the formation of the amido complex is facilitated by coordination of ammonia to palladium to increase the acidity of the ammonia, and the aryl group bound to palladium affects the Lewis acidity of the metal center (Scheme 2). …”

Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides, and Sulfonates: A General Method for the Preparation of Primary Arylamines

2009

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We report that the complex generated from Pd[P(o-tol)3]2 and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader substrate scope. The utility of this method to generate amides, imides and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides. Mechanistic studies show that Pd[P(o-tol)3]2 and CyPF-t-Bu generate a more active and general catalyst than that generated from CyPF-t-Bu and palladiun(II) precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia and base.

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Section: Resultsmentioning

confidence: 99%

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides, and Sulfonates: A General Method for the Preparation of Primary Arylamines

2009

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“…[16][17][18][19][20] Thus, predictions of partial structure factors, partial radial distribution † Part of the special issue "Bruce Berne Festschrift". functions, coordination numbers of the ions, hypotheses about the shape of their first solvation shells, and dynamical information are available.…”

Section: Introductionmentioning

confidence: 99%

Protonic Defects in Hydrogen Bonded Liquids: Structure and Dynamics in Ammonia and Comparison with Water

Liu

Tuckerman

2001

J. Phys. Chem. B

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The structural, dynamical, and electronic properties of ionic defects in liquid ammonia at 260 K created by the addition or removal of a proton have been studied using the method of ab initio molecular dynamics. These protonic defects correspond to the ammonium (NH 4 + ) and amide (NH 2 -) ions in the liquid and are the analogues of the H 3 O + and OH -ions in water. For this reason, direct comparison between the protonic defects in ammonia and those in water can be made. In particular, it is found that the NH 4 + exhibits a characteristic cationic solvation pattern, in which it donates four hydrogen bonds to neighboring ammonia molecules, giving it a coordination number of 4. The NH 2 -ion is found to have a coordination number between 7 and 8 in liquid ammonia, a number higher than would be expected based on the number of hydrogen bonds it can accept and donate. It is found that about 40% of this is due to hydrogen bonding but that these hydrogen bonds are all accepted by the amide nitrogen. Moreover, the hydrogen bonds are often arranged in a planar configuration (perpendicular to the C 2 axis of the amide), a solvation pattern also exhibited by OHin water. The rationale for the high coordination of NH 2 -is found to differ markedly from that which emerges from interpretation of spectral data. Unlike H 3 O + and OH -in water, no proton transfer is exhibited in either the NH 4 + system or the NH 2 -system. The results presented here lead to a possible explanation for the lack of structural diffusion. Nevertheless, the solvation structures formed by the NH 4 + and NH 2 -ions in ammonia and their associated electronic properties possess many similarities with the water ions in water, and from the studies performed here, a number of important patterns begin to emerge that may be applicable to protonic defects in other hydrogen-bonded liquids.

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“…Liquid ammonia is a basic solvent with a very low self‐ionisation constant (pK a = 27.6 at 25°C), and the ionisation of acids in this solvent generates equivalent amounts of the conjugate base and ammonium ion (Eqn ). Many ionic species will be strongly associated because of the low dielectric constant of liquid ammonia and conductivity data shows that ion pairing occurs

{HA + NH}_{3} \overset{K_{i}}{⇌} {(][, A^{-} {NH}_{4}^{+})}_{ı p} \overset{K_{d}}{⇌} {normalA}^{true-} + {normalNH}_{4}^{+}

even at low concentrations and larger aggregates may form at higher concentrations .…”

Section: Resultsmentioning

confidence: 99%

“…Liquid ammonia thus renders anionic nucleophiles more ‘naked’ than in water and are therefore expected to be more reactive and, conversely, make anionic leaving groups poorer relative to that in water. The normalised donor number (DN N ) of liquid ammonia is 1.52, greater than that of HMPTA (1.0), while its autoprotolysis constant gives a pK a of 27.6 (25°C), compared with 14.0 for water (25°C) …”

Section: Introductionmentioning

confidence: 97%

The ammonolysis of esters in liquid ammonia

Griffin

Atherton

Page

2013

J of Physical Organic Chem

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The Heat Capacity, Entropy and Heat Content of Sodium Amide from 15 to 300°K. The Thermodynamics of Amide Ion in Liquid Ammonia¹

Cited by 27 publications

References 0 publications

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides, and Sulfonates: A General Method for the Preparation of Primary Arylamines

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides, and Sulfonates: A General Method for the Preparation of Primary Arylamines

Protonic Defects in Hydrogen Bonded Liquids: Structure and Dynamics in Ammonia and Comparison with Water

The ammonolysis of esters in liquid ammonia

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The Heat Capacity, Entropy and Heat Content of Sodium Amide from 15 to 300°K. The Thermodynamics of Amide Ion in Liquid Ammonia1

Cited by 27 publications

References 0 publications

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides, and Sulfonates: A General Method for the Preparation of Primary Arylamines

Palladium-Catalyzed Coupling of Ammonia with Aryl Chlorides, Bromides, Iodides, and Sulfonates: A General Method for the Preparation of Primary Arylamines

Protonic Defects in Hydrogen Bonded Liquids: Structure and Dynamics in Ammonia and Comparison with Water

The ammonolysis of esters in liquid ammonia

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The Heat Capacity, Entropy and Heat Content of Sodium Amide from 15 to 300°K. The Thermodynamics of Amide Ion in Liquid Ammonia¹