Lanthanide(iii) triflates as recyclable catalysts for atom economic aromatic nitration

Waller, Francis J.; Barrett, Anthony G. M.; Braddock, D. Christopher; Ramprasad, Dorai

doi:10.1039/a700546f

Cited by 104 publications

(59 citation statements)

References 12 publications

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“…Nitration of the phenol as a special case has been studied using various nitrating agents under different conditions [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Recently, in this connection we have reported the applications and mechanism of reaction of some hydrated metal nitrates and their dinitrogen tetroxide complex analogues for the nitration of phenols under various conditions [21].…”

Section: Methodsmentioning

confidence: 99%

Silica sulfuric acid/NaNO2 as a novel heterogeneous system for production of thionitrites and disulfides under mild conditions

2001

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Section: Methodsmentioning

confidence: 99%

Silica sulfuric acid/NaNO2 as a novel heterogeneous system for production of thionitrites and disulfides under mild conditions

2001

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“…Recently, it was found that lanthanide triflates (l ± 10 mol %) [Ln(OTf) 3 , Ln Yb, Sc, Y. etc] can catalyze the nitration of a range of simple aromatic compounds in good to excellent yield using stoichiometric quantities of 69% nitric acid, the only by-product is water and the catalyst can be readily recycled by simple evaporation. [8] However, these nitrations were carried out in 1,2-dichloroethane, an environmentally hazardous solvent, under reflux. Previously, we reported two more ecosafer nitration processes: 1) using perfluorinated rare earth metal salts Ln(OPf) 3 [Ln(OSO 2 C 8 F 17 ) 3 ] as catalysts without halogenated organic solvent and 2) electrophilic aromatic nitration using perfluorinated rare earth metal salts in the fluorous phase.…”

Section: Introductionmentioning

confidence: 99%

Electrophilic Aromatic Nitration Using a Mixed Catalyst of Lithium, Molybdenum, Ytterbium on Silica Gel

Shi

Cui

2003

Adv Synth Catal

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A novel mixed catalyst of LiClO 4 (15% w/w), Yb(OPf) 3 (15% w/w, Pf perfluorooctanesulfonyl), MoO 3 (15% w/w) on silica gel for electrophilic aromatic nitration reaction has been explored. The nitration reactions were accomplished by this mixed catalyst and nitric acid under solvent-free conditions. Moreover, the mixed catalyst can be easily recovered from the aqueous layer by heating in an oven and reused for the next nitration reaction.

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“…[12,13] For example, solutions of the small scandium(iii) and ytterbium(iii) ions were found to be significantly more efficient as recyclable catalysts in the nitration of aromatic compounds in organic solvents than the lanthanum(iii), praseodymium(iii) and europium(iii) trifluoromethanesulfonates. [35,43] The reaction produces water molecules that will expel trifluoromethanesulfonate ions from the first coordination sphere in a mixed reaction medium. [44] "The compatibility of lanthanoid(iii) triflate salts with water and yet their apparent ability to function as strong Lewis acids is somewhat paradoxical."…”

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Highly Hydrated Cations: Deficiency, Mobility, and Coordination of Water in Crystalline Nonahydrated Scandium(III), Yttrium(III), and Lanthanoid(III) Trifluoromethanesulfonates

Abbasi

Lindqvist‐Reis

Eriksson

et al. 2005

Chemistry A European J

113

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Trivalent lanthanide-like metal ions coordinate nine water oxygen atoms, which form a tricapped trigonal prism in a large number of crystalline hydrates. Water deficiency, randomly distributed over the capping positions, was found for the smallest metal ions in the isomorphous nonahydrated trifluoromethanesulfonates, [M(H2O)n](CF3SO3)3, in which M = Sc(III), Lu(III), Yb(III), Tm(III) or Er(III). The hydration number n increases (n = 8.0(1), 8.4(1), 8.7(1), 8.8(1) and 8.96(5), respectively) with increasing ionic size. Deuterium (2H) solid-state NMR spectroscopy revealed fast positional exchange between the coordinated capping and prism water molecules; this exchange started at temperatures higher than about 280 K for lutetium(III) and below 268 K for scandium(III). Similar positional exchange for the fully nonahydrated yttrium(III) and lanthanum(III) compounds started at higher temperatures, over about 330 and 360 K, respectively. An exchange mechanism is proposed that can exchange equatorial and capping water molecules within the restrictions of the crystal lattice, even for fully hydrated lanthanoid(III) ions. Phase transitions occurred for all the water-deficient compounds at approximately 185 K. The hydrated scandium(III) trifluoromethanesulfonate transforms reversibly (DeltaH degrees = -0.80(1) kJ mol(-1) on cooling) to a trigonal unit cell that is almost nine times larger, with the scandium ion surrounded by seven fully occupied and two partly occupied oxygen atom positions in a distorted capped trigonal prism. The hydrogen bonding to the trifluoromethanesulfonate anions stabilises the trigonal prism of water ligands, even for the crowded hydration sphere of the smallest metal ions in the series. Implications for the Lewis acid catalytic activity of the hydrated scandium(III) and lanthanoid(III) trifluoromethanesulfonates for organic syntheses performed in aqueous media are discussed.

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Lanthanide(iii) triflates as recyclable catalysts for atom economic aromatic nitration

Cited by 104 publications

References 12 publications

Silica sulfuric acid/NaNO2 as a novel heterogeneous system for production of thionitrites and disulfides under mild conditions

Silica sulfuric acid/NaNO2 as a novel heterogeneous system for production of thionitrites and disulfides under mild conditions

Electrophilic Aromatic Nitration Using a Mixed Catalyst of Lithium, Molybdenum, Ytterbium on Silica Gel

Highly Hydrated Cations: Deficiency, Mobility, and Coordination of Water in Crystalline Nonahydrated Scandium(III), Yttrium(III), and Lanthanoid(III) Trifluoromethanesulfonates

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