An improved protocol for aerobic oxidation of acetals to esters catalyzed by N-hydroxy phthalimide (NHPI) and lipophilic Co(II) complexes

Karimi, Babak; Rajabi, Jamshid

doi:10.1016/j.molcata.2004.10.014

Cited by 19 publications

(5 citation statements)

References 27 publications

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“…2‐Hydroxyethyl hexanoate ( 7 d ) : Column chromatography (PE/EA 2:1); colourless oil; yield: 54.5 mg, 340 μmol, 34 %; R f (PE/EA 2:1)=0.16; 1 H NMR (300 MHz, CDCl 3 , 25 °C, TMS): δ =0.78 (t, J (H,H)=6.9 Hz, 3 H; CH 3 ), 1.28 (m, 4 H; CH 2 ), 1.61 (m, 2 H; CH 2 ), 2.32 (m, 2 H; CH 2 ; overlapping with 1 H; OH), 3.71 (m, 2 H, CH 2 ), 4.18 ppm (m, 2 H; CH 2 ); 13 C NMR (75 MHz, CDCl 3 , 25 °C, TMS): δ =14.09, 22.50, 24.80, 31.48, 34.36, 61.48, 66.10 ppm. All spectroscopic data are in good agreement with the previously reported data 40…”

Section: Methodssupporting

confidence: 92%

Gold Catalysis: In Situ EXAFS Study of Homogeneous Oxidative Esterification

Hashmi

Lothschütz

Ackermann

et al. 2010

Chemistry A European J

128

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Gold complexes were prepared and investigated as catalysts for the oxidative esterification of aldehydes. Stabilisation by pyridine ligands gave good conversions and the in situ extended X-ray absorption fine structure (EXAFS) study of the reactions indicated that the reaction mixtures contained only mononuclear gold species. Thus, this is the first proof for a homogeneous gold-catalysed oxidation reaction; the presence of nanoparticles could be excluded experimentally.

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Section: Methodssupporting

confidence: 92%

Gold Catalysis: In Situ EXAFS Study of Homogeneous Oxidative Esterification

Hashmi

Lothschütz

Ackermann

et al. 2010

Chemistry A European J

128

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show abstract

“…This order is caused probably by two factors: one is the redox activity of these transition metal species, and the other is the solubility of these transition metal salts in the solvent or their lipophilic property. 38 As described above, the step that superoxometal complex induces or initiates the generation of PINO radical is a key step in the total oxidation process of ethylbenzene. At the same time, the metal elements in higher oxidation state are reduced to the species in lower valence state.…”

Section: Resultsmentioning

confidence: 99%

Synchronously Synthesizing and Immobilizing N-Hydroxyphthalimide on Polymer Microspheres and Catalytic Performance of Solid Catalyst in Oxidation of Ethylbenzene by Molecular Oxygen

Gao

Meng

Yang

2015

Org. Process Res. Dev.

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Cross-linked copolymer microspheres of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) were first prepared (GMA/MMA microspheres), and then N-hydroxyphthalimide (NHPI) was synchronously synthesized and immobilized on the GMA/MMA microspheres to form a recyclable heterogeneous catalyst, GMA/MMA-NHPI, via several steps of polymer reactions by molecular design. A compositional catalyst was made with GMA/MMA-NHPI microspheres as the main catalyst and a transition metal salt as co-catalyst, and this compositional catalyst was used in the oxidation of ethylbenzene by molecular oxygen. The mechanism of the catalytic oxidation reaction was investigated, and the effects of some main factors on the catalytic oxidation reaction were examined. The experimental results show that, among several transition metal salts, Co(OAc) 2 is the best co-catalyst, and the catalytic activity order is Co(OAc) 2 > CoCl 2 > Mn(OAc) 2 > CuCl 2 . The compositional catalyst composed of GMA/MMA-NHPI microspheres and Co(OAc) 2 can effectively catalyze the oxidation of ethylbenzene by molecular oxygen under mild conditions (at 100°C and ordinary molecular oxygen pressure), and transform ethylbenzene into acetophenone with a yield of 20.1% and a selectivity of 75.8% in 25 h. The catalytic oxidation follows a free radical chain reaction mechanism. The type of solvent used significantly affects the catalytic oxidation reaction, and acetic acid is a more suitable solvent compared with acetonitrile. For the compositional catalyst, there is an optimum amount of added co-catalyst Co(OAc) 2 ; correspondingly, the optimum ratio of immobilized NHPI on GMA/MMA-NHPI microspheres to Co(OAc) 2 is 14:1. The appropriate reaction temperature is 100°C. The solid catalyst, GMA/MMA-NHPI microspheres, exhibits good recycling and reusing properties.

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“…Even though the oxidation of acetal groups to acids or esters is known in the literature, it has, to the best of our knowledge, never been shown for the synthesis of dicarboxylic acids. − To obtain adipic acid, we used Oxone (KHSO 5 ·0.5KHSO 4 ·0.5K 2 SO 4 ) and oxygen gas (Scheme ). About 70% of the desired compound was obtained with both oxidants, together with small amounts of starting material, adipic aldehyde, the corresponding glycol ester, and ethylene glycol.…”

Section: Results and Discussionmentioning

confidence: 99%

Synthesis of Adipic Acid, 1,6-Hexanediamine, and 1,6-Hexanediol via Double-n-Selective Hydroformylation of 1,3-Butadiene

et al. 2016

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A method for the synthesis of the industrially relevant monomers adipic acid, 1,6-hexanediol (HDO), and 1,6-hexanediamine (HMD) via isomerizing hydroformylation of 1,3-butadiene is described. The aldehyde intermediates are protected in situ as acetals to avoid hydrogenation to pentanal. Adipic aldehyde diacetal is obtained in good yields, and the first examples for the conversion toward adipic acid, 1,6-hexanediol, and 1,6-hexanediamine are shown.

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An improved protocol for aerobic oxidation of acetals to esters catalyzed by N-hydroxy phthalimide (NHPI) and lipophilic Co(II) complexes

Cited by 19 publications

References 27 publications

Gold Catalysis: In Situ EXAFS Study of Homogeneous Oxidative Esterification

Gold Catalysis: In Situ EXAFS Study of Homogeneous Oxidative Esterification

Synchronously Synthesizing and Immobilizing N-Hydroxyphthalimide on Polymer Microspheres and Catalytic Performance of Solid Catalyst in Oxidation of Ethylbenzene by Molecular Oxygen

Synthesis of Adipic Acid, 1,6-Hexanediamine, and 1,6-Hexanediol via Double-n-Selective Hydroformylation of 1,3-Butadiene

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