Preparation of Derivatives of Pyrrole and Pyridine by Hydrogenation

Adkins, Homer; Wolff, I. A.; Pavlic, A. A.; Hutchinson, E. G.

doi:10.1021/ja01236a025

Cited by 24 publications

(5 citation statements)

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“…Hydrogenation of pyrrole and its derivative was achieved over precious metals (Pt, Pd, Ru, Rh) or Raney nickel as early as the 1930s. − Diastereoselection products of hydrogenation of pyrrole derivatives were also obtained by adding a chiral auxiliary to the heterogeneous catalyst . The poisoning effect of pyrrole in hydrogenation is attributed to the unshared pair of electrons on N, which is commonly eliminated using protic acids .…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Pyrrole Hydrogenation on Ru(0001) and Hydrogen Molybdenum Bronze Surfaces

Huang

Cheng

2015

J. Phys. Chem. C

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Hydrogenation of pyrrole and its derivatives is of fundamental importance in chemical and pharmaceutical processes for which a mechanistic understanding is still lacking. The objective of the present study is to unveil the energetic profiles of pyrrole hydrogenation on Ru(0001) along the prescribed routes by periodic density functional theory (DFT) calculations. It was found that the activation energy of the rate-limiting step of the hydrogenation process is 1.05 eV. The calculated desorption energy of the hydrogenated product is 1.24 eV. We also found hydrogen molybdenum bronze (H x MoO3) to be an efficient catalyst material for pyrrole hydrogenation via detailed mechanistic investigations. H x MoO3 is expected to outperform ruthenium owning to the lower hydrogenation barrier and more facile desorption of the product. We rationalize the more favorable energetics of pyrrole/H x MoO3 by the lower adsorption energy of pyrrole and the protonic nature of H in H x MoO3. The chemistry revealed in this work provides meaningful insight into the design of low-cost hydrogenation catalysts.

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Section: Introductionmentioning

confidence: 99%

Mechanisms of Pyrrole Hydrogenation on Ru(0001) and Hydrogen Molybdenum Bronze Surfaces

Huang

Cheng

2015

J. Phys. Chem. C

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“…These poisoning effects can be reduced over Pt catalysts by conversion of these reactants into a form in which the nitrogen atom is shielded (e.g., by adding protic acids). [9][10][11][12][13] The hydrogenation of pyrrole derivatives was kinetically studied by Adkins and co-workers [14][15][16] over Raney nickel and other catalysts, and later studies report on hydrogenation over supported precious metal catalysts (Pd/ C, Ru/C, Rh/C, and Rh/Al 2 O 3 ) in liquid phase by Hegedus et al [17][18][19][20][21][22] Under relatively mild reaction conditions (25-80 °C) and by using nonacidic solvents, the hydrogenation of pyrrole derivatives showed higher activities on Rh than on Pt-supported catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…It has long been known that nitrogen-containing compounds have inhibiting effects on the catalysts used for hydrogenation because of their unshared pair of electrons. These poisoning effects can be reduced over Pt catalysts by conversion of these reactants into a form in which the nitrogen atom is shielded (e.g., by adding protic acids). – The hydrogenation of pyrrole derivatives was kinetically studied by Adkins and co-workers – over Raney nickel and other catalysts, and later studies report on hydrogenation over supported precious metal catalysts (Pd/C, Ru/C, Rh/C, and Rh/Al 2 O 3 ) in liquid phase by Hegedus et al – Under relatively mild reaction conditions (25−80 °C) and by using nonacidic solvents, the hydrogenation of pyrrole derivatives showed higher activities on Rh than on Pt-supported catalysts.…”

Section: Introductionmentioning

confidence: 99%

Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

Kliewer¹,

Bieri²,

Somorjai³

2008

J. Phys. Chem. C

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Sum-frequency generation (SFG) surface vibrational spectroscopy and kinetic measurements using gas chromatography have been used to study the adsorption and hydrogenation of pyrrole over both Pt(111) and Rh(111) single-crystal surfaces at Torr pressures (3 Torr pyrrole, 30 Torr H 2 ) to form pyrrolidine and the minor product butylamine. Over Pt(111) at 298 K it was found that pyrrole adsorbs in an upright geometry cleaving the N-H bond to bind through the nitrogen evidenced by SFG data. Over Rh(111) at 298 K pyrrole adsorbs in a tilted geometry relative to the surface through the π-aromatic system. A pyrroline surface reaction intermediate, which was not detected in the gas phase, was seen by SFG during the hydrogenation over both surfaces. Significant enhancement of the reaction rate was achieved over both metal surfaces by adsorbing 1-methylpyrrole before reaction. SFG vibrational spectroscopic results indicate that reaction promotion is achieved by weakening the bonding between the N-containing products and the metal surface because of lateral interactions on the surface between 1-methylpyrrole and the reaction species, reducing the desorption energy of the products. It was found that the ring-opening product butylamine was a reaction poison over both surfaces, but this effect can be minimized by treating the catalyst surfaces with 1-methylpyrrole before reaction. The reaction rate was not enhanced with elevated temperatures, and SFG suggests desorption of pyrrole at elevated temperatures.

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“…Catalytic reduction of the oximes of acyl-and formylpyrroles over Raney nickel generally gives the amines in moderate to good yields, (58) but the conversion of acetylpyrroles into the corresponding ethyl compounds via reduction of the oximes has also been reported. (58) Little is known of the oxidation of the pyrryl imines, azines, or oximes.…”

Section: Oxidation and Reductionmentioning

confidence: 99%

Ketones, Aldehydes, and Carboxylic Acid Derivatives of Pyrrole

1977

The Chemistry of Pyrroles

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A. Resonance Interaction between the Pyrrole Ring and the Carbonyl SubstituentThe low reactivity, compared with other aromatic aldehydes and ketones, of a-acylpyrroles with nucleophiles (see Section B) was originally explained as being due to the preferential existence of the acylpyrrole (Al) in the alternative tautomeric form (A2). (1) It has also been suggested that 2-formylpyrrole could be better formulated as the dimer (A3), (2) whilst other rationales for the abnormal behaviour of acylpyrroles were based upon the high stability of intermediate chelates (3) or of the pyrryl anions produced during the reactions with nucleophiles. (4) It is now evident from spectroscopic data

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Preparation of Derivatives of Pyrrole and Pyridine by Hydrogenation

Cited by 24 publications

References 0 publications

Mechanisms of Pyrrole Hydrogenation on Ru(0001) and Hydrogen Molybdenum Bronze Surfaces

Mechanisms of Pyrrole Hydrogenation on Ru(0001) and Hydrogen Molybdenum Bronze Surfaces

Pyrrole Hydrogenation over Rh(111) and Pt(111) Single-Crystal Surfaces and Hydrogenation Promotion Mediated by 1-Methylpyrrole: A Kinetic and Sum-Frequency Generation Vibrational Spectroscopy Study

Ketones, Aldehydes, and Carboxylic Acid Derivatives of Pyrrole

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