Hydrodehalogenation of aromatic chlorides with NaBH4 in the presence of Ni(0) catalysts

Scrivanti, Alberto; Vicentini, Barbara; Beghetto, Valentina; Chessa, Gavino; Matteoli, Ugo

doi:10.1016/s1387-7003(98)00065-3

Cited by 16 publications

(10 citation statements)

References 16 publications

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“…Scheme 9. HDH of Ar-X using Ni(PPh 3 ) 2 Cl 2 with 2 equivalents of PPh 3 in ethanol/pyridine with subsequent addition of excess NaBH 4 (benzene was produced with 100% conversion using 2 mmol 1,2,3-TCB dissolved in 10 mL ethanol/pyridine 9/1 with addition of 0.05 mmol Ni(PPh 3 ) 2 Cl 2 , 0.1 mmol PPh 3 and 7 mmol NaBH 4 at 70 • C/3 h) [60].…”

Section: Hydrogentransfer In Ni-catalyzed Hydrodehalogenation Reactionsmentioning

confidence: 99%

Applicability of Nickel-Based Catalytic Systems for Hydrodehalogenation of Recalcitrant Halogenated Aromatic Compounds

Weidlich

2021

Catalysts

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This review summarizes recent applications of nickel as a nonprecious metal catalyst in hydrodehalogenation (HDH) reactions of halogenated aromatic compounds (Ar–Xs). Nickel-based HDH catalysts were developed for reductive treatment of both waste containing concentrated Ar–Xs (mainly polychlorinated benzenes) and for wastewater contaminated with Ar–Xs. Ni-catalyzed HDH enables the production of corresponding nonhalogenated aromatic products (Ar–Hs), which are principally further applicable/recyclable and/or Ar–Hs, which are much more biodegradable and can be mineralized during aerobic wastewater treatment. Developed HDH methods enable the utilization of both gaseous hydrogen via the direct HDH process or other chemical reductants as a source of hydrogen utilized in the transfer of the hydrodehalogenation process. This review highlights recent and major developments in Ni-catalyzed hydrodehalogenation topic since 1990.

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Section: Hydrogentransfer In Ni-catalyzed Hydrodehalogenation Reactionsmentioning

confidence: 99%

Applicability of Nickel-Based Catalytic Systems for Hydrodehalogenation of Recalcitrant Halogenated Aromatic Compounds

Weidlich

2021

Catalysts

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“…The same group [44] later studied the reduction of a series of pure PCB congeners with NaBH 4 . The solvent properties determined the catalytic efficiency in the transformation of 1,2,3-trichlorobenzene with a related system at 70 8C: using ethanol/pyridine solvent mixtures, benzene was produced a high rate [45]. High selectivity for 2-, 3-, and 4-chloro displacement from di-and trichlorobiphenyls has been found.…”

Section: Simple and Complex Metal Hydridesmentioning

confidence: 99%

“…Simple and complex metal hydrides as strong nucleophiles easily displace the halide bound to the central atom of the catalyst by hydride transfer [40,45,[62][63][64][65][66][67]. Alcoholates [97,98,100,106,108], formates [93,96,100,112], and metal alkyls [114,115,117] also substitute the halogen atom on the transition metal, after which the hydrogen transfer takes place from the alkoxy, formato and alkyl ligands formed [3,211].…”

Section: Reaction Steps Involving the Reducing Agentsmentioning

confidence: 99%

Dehalogenation Reactions

and¹,

Simon²

2006

The Handbook of Homogeneous Hydrogenation

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Reductive dehalogenation -one of the earliest reactions described in the organic chemical literature -has achieved special significance since the 1980s when the harmful properties of numerous halogenated (chiefly chlorinated) hydrocarbons became clear. The identification of methods capable of neutralizing or, at least, diminishing these dangers, remains a major challenge for chemistry. It is reasonable to convert stocks of the prohibited chemicals (e.g., polychlorobiphenyls, PCBs; chlorofluorocarbons, CFCs) to valuable products as far as possible. At the same time, the halogen-containing wastes should be detoxified by degradation. During the past two decades, the mainly heterogeneous (but also homogeneous) catalytic dehalogenation provided a major share towards solving these problems. Within this period, substantial progress was also made in the application of these reactions in organic syntheses.Hydrodehalogenation -that is, hydrogenolysis of the carbon-halogen bondinvolves the displacement of a halogen bound to carbon by a hydrogen atom. This chapter is devoted to dehalogenations mediated by transition-metal complexes (Eq. (1)): ÀC j j ÀX reducing agent L n Mj 3 ÀC j j ÀH Y 1 where X = F, Cl, Br, I, and [L n M] = a transition metal complex. The use of a wide variety of reducing agents (H 2 , hydrides of metals and metalloids, organic reductants, etc.) under the most diverse reaction conditions (e.g., one-or two-phase systems) has been reported. Organic halides have also been reduced by electrochemical and photochemical methods in the presence of compounds of the type [L n M]. Reductive transformations of organic halides not relevant to Eq.(1) (e.g., coupling reactions) and dehalogenation of acyl halides will not be included here. 513The Handbook of Homogeneous Hydrogenation. Edited by J. G. de Vries and C. J. ElsevierThe reactivity of the carbon-halogen bond in Eq. (1) depends on several factors: · the nature of the halogen atom; · the environment of the halogen atom in the molecule; and · the reagents and conditions used in Eq. (1) [1].The order of reactivity of the C-X bond (generally: I > Br > Cl > F) is consistent with its strength. For instance, the experimentally found dissociation energies for phenyl halides (D Ph-X ) are 528, 402, 339, and 272 kJ mol -1 at 298 K for X = F, Cl, Br, and I, respectively [2]. Consequently, catalytic defluorination in the literature is comparatively rare. The different reactivity of the C-X bonds renders possible the selective dehalogenation of compounds containing two dissimilar halides, leaving intact the stronger C-X bond.

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“…Catalytic hydrodehalogenation (HDH) of organic halides is of great interest in organic synthesis and environmental pollution remediation efforts. [1][2][3][4][5] Among the numerous HDH methods that have been developed, [6][7][8][9][10][11][12][13][14][15] nickel pincer complexes have recently emerged as attractive, stable, homogeneous catalysts for such reactions. [16][17][18][19][20][21] In 2012, the Hu group reported that "Nickamine" [16,22] (complex A in Figure 1) could be used as a precatalyst for hydrodehalogenation reactions of both aryl and alkyl halides by employing diethyloxymethylsilane as reductant and sodium methoxide as base.…”

Section: Introductionmentioning

confidence: 99%

The Electronic Properties of Ni(PNN) Pincer Complexes Modulate Activity in Catalytic Hydrodehalogenation Reactions

Wang

Gardinier

2020

Eur J Inorg Chem

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Three chloronickel(II) complexes of PNN‐ pincer ligands with pyrazolyl and diphenylphosphino donors appended to different arms of diarylamido anchors were prepared and fully characterized. The three derivatives (1‐OMe, 1‐Me, 1‐CF3) differ only by the identity of the para‐aryl substituent on the pyrazolyl arm with 1‐OMe being 310 mV easier to oxidize than 1‐CF3. All three complexes are competent catalysts for hydrodehalogenation reactions of 1‐bromooctane and a variety of aryl halides in dimethylacetamide using NaBH4 as both base and hydride source. Comparative studies using diverse substrates showed that catalytic activity correlates with electron donor properties; 1‐OMe was superior to the other two. Deuterium labeling studies verified NaBD4 as the deuteride source and excluded solvent‐assisted radical pathways.

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Hydrodehalogenation of aromatic chlorides with NaBH4 in the presence of Ni(0) catalysts

Cited by 16 publications

References 16 publications

Applicability of Nickel-Based Catalytic Systems for Hydrodehalogenation of Recalcitrant Halogenated Aromatic Compounds

Applicability of Nickel-Based Catalytic Systems for Hydrodehalogenation of Recalcitrant Halogenated Aromatic Compounds

Dehalogenation Reactions

The Electronic Properties of Ni(PNN) Pincer Complexes Modulate Activity in Catalytic Hydrodehalogenation Reactions

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