Magnesium-mediated ortho-specific formylation and formaldoximation of phenols

Aldred, Robert; Johnston, R.; Levin, Daniel; Neilan, James P.

doi:10.1039/p19940001823

Cited by 62 publications

(42 citation statements)

References 10 publications

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“…[32,39] 3-Bromomethyl-2-hydroxy-5-tert-butylbenzaldehyde and its 5-nonyl homologue were made by the procedure described recently by Wang et al (Scheme 3).…”

Section: Methodsmentioning

confidence: 99%

Anion Selectivity in Zwitterionic Amide‐Functionalised Metal Salt Extractants

Galbraith

Wang

et al. 2007

Chemistry A European J

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Amide-functionalised salen ligands capable of extracting metal salts have been synthesised and characterised. Single-crystal X-ray structure determinations of complexes of NiSO4, [Ni(L)(SO4)], confirm that the ionophores are in a zwitterionic form with Ni(II) bound in the deprotonated salen moiety and the SO4(2-) ion associated with protonated pendant N'-amidopiperazine groups. Treatment of [Ni(L)(SO4)] with base removes the protons from the pendant amido-amine group resulting in loss of the SO4(2-) ion and formation of metal-only complexes of type [Ni(L-2H)], which have been characterized by single-crystal X-ray diffraction. Three of the ligands with solubilities suitable for solvent extraction studies show loading and stripping pH-profiles that are suitable for the recovery of CuSO4 or CuCl2 from industrial leach solutions. The copper-only complexes, [Cu(L-2H)], are selective for Cl- over SO4(2-) in both solvent extraction and bulk liquid membrane transport experiments and were found to bind Cl- in two steps via the formation of a 1:1:1 [Cu(L-H)Cl] assembly, followed by a 1:1:2 [Cu(L)Cl2] assembly as the pH of the aqueous phase is lowered. The anion transport selectivity was evaluated for a number of other mono-charged anions and interestingly the ligands were found to display a preference for the Br- ion. To probe the influence of the Hofmeister bias on the selectivity of anion complexation, single-phase potentiometric titration experiments were employed to investigate the binding of SO4(2-) and Cl- by one of the copper only complexes, [Cu(L-2H)] in 95 %/5 % MeOH/water. Under these conditions selectivity was reversed (SO4(2-)>Cl-) confirming that the Hofmeister bias, which reflects the relative hydration energies of the anions, dominates the selectivity of anion extraction from aqueous media into CHCl3.

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“…[32,39] 3-Bromomethyl-2-hydroxy-5-tert-butylbenzaldehyde and its 5-nonyl homologue were made by the procedure described recently by Wang et al (Scheme 3).…”

Section: Methodsmentioning

confidence: 99%

Anion Selectivity in Zwitterionic Amide‐Functionalised Metal Salt Extractants

Galbraith

Wang

et al. 2007

Chemistry A European J

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“…4b,d-f were synthesised using the method of Levin et al 37 Although the unoptimised isolated yield of 21% for 4b is low, it compares favourably with yields reported in the literature using traditional methods such as the Duff reaction (14%) 38 or the Reimer-Tiemann reaction (17%). 39 Indeed it is actually better than expected because just 5% was reported by Levin and co-workers for 3-fluorosalicylaldehyde.…”

Section: Resultsmentioning

confidence: 88%

“…The resolution and liberation of (AE)-trans-cyclohexane-1,2-diamine were carried out according to literature procedures. 48 51 for o-formylation. General method: The phenol (1 equiv) was added to a methanolic solution of magnesium methoxide (0.6 equiv) under a N 2 atmosphere in a three-neck RB flask equipped for reduced pressure distillation.…”

Section: Generalmentioning

confidence: 99%

Ligand tuning in the chromium–salen-mediated asymmetric epoxidation of alkenes

McGarrigle

Murphy

Gilheany

2004

Tetrahedron: Asymmetry

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“…[47,48] Results and Discussion L1-L10 were readily obtained in high yields (see ESI) by reaction of methyl or phenyl hydrazine with the substituted salicylaldehydes 1-5 which were prepared by formylation and 3-substitution of 4-tert-butylphenol (Scheme 1). A stock of 5-tertbutyl-2-hydroxybenzaldehyde (1) was synthesized by the Levin method, [49] and the nitro-substituted (3) and bromo-substituted (4) salicylaldehydes were produced by optimizing literature conditions for electrophilic substitution. [50] The methoxysubstituted salicylaldehyde (5) was prepared from its bromo analogue 4 by a modification of the literature method.…”

Section: Cumentioning

confidence: 99%

Salicylaldehyde Hydrazones: Buttressing of Outer-Sphere Hydrogen-Bonding and Copper Extraction Properties

et al. 2017

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Salicylaldehydes hydrazones are weaker copper extractants than their oxime derivatives which are used in hydrometallurgical processes to recover approximately 20% of the world's copper. Their strength, based on the extraction equilibrium constant Ke, can be increased by nearly three orders of magnitude by incorporating electron-withdrawing or hydrogen bond acceptor groups (X) ortho to the phenolic OH group of the salicylaldehyde unit. DFT calculations suggest that the effects of the 3-X substituents arise from a combination of their influence on the acidity of the phenol in the pHdependent equilibrium:and on their ability to "buttress" interligand hydrogen bonding by interacting with the hydrazone N-H donor group. X-ray crystal structure determination and computed structures indicated that in both the solid state and the gas phase, coordinated hydrazone groups are less planar than coordinated oximes and this has an adverse effect on intramolecular hydrogen bond formation to the neighbouring phenolate oxygen atoms.

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Magnesium-mediated ortho-specific formylation and formaldoximation of phenols

Cited by 62 publications

References 10 publications

Anion Selectivity in Zwitterionic Amide‐Functionalised Metal Salt Extractants

Anion Selectivity in Zwitterionic Amide‐Functionalised Metal Salt Extractants

Ligand tuning in the chromium–salen-mediated asymmetric epoxidation of alkenes

Salicylaldehyde Hydrazones: Buttressing of Outer-Sphere Hydrogen-Bonding and Copper Extraction Properties

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