Purification of Organic Chemicals

Armarego, W. L. F.

doi:10.1016/b978-0-12-805457-4.50003-3

Cited by 207 publications

(159 citation statements)

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“…26 Most anhydrous solvents (dichloromethane and diethyl ether) were obtained by passing through activated alumina columns on a solvent purification system. Zinc dust (<10 μm), lithium perchlorate, n -butyllithium (2.5 M in hexane), LiAlH 4 (1.0 M in Et 2 O), potassium triethylborohydride (1.0 M in THF), 2-phenylpropanoic acid, 2-phenylbutanoic acid, diphenylacetyl chloride, phenylacetic acid, ethylethynyl ether, and 2-pyridone were purchased and used as received.…”

Section: Methodsmentioning

confidence: 99%

“…Propionyl chloride, butyryl chloride, acetoxyacetyl chloride, 4-chlorobutyryl chloride, hexanoyl chloride, octanoyl chloride, valeroyl chloride, and trimethylsilyl chloride were purchased and distilled prior to use. 26 Iatrobeads (neutral silica, 60μM particle size), and TLC plates (UV254, 250μM) were used as received. Methylphenylketene, ethylphenylketene, n -butylphenylketene, isobutylphenylketene, diphenylketene, dimethylketene and TMS-ketene were prepared according to literature procedures.…”

Section: Methodsmentioning

confidence: 99%

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Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations

et al. 2016

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In this article we describe extensive studies of the catalytic asymmetric heterodimerization of ketenes to give ketene heterodimer β-lactones. The optimal catalytic system was determined to be a cinchona alkaloid derivative (TMS-quinine or Me-quinidine). The desired ketene heterodimer β-lactones were obtained in good to excellent yields (up to 90%), with excellent levels of enantioselectivity (≥90% ee for 33 Z- and E-isomer examples), good to excellent Z-olefin isomer selectivity (≥90:10 for 20 examples), and with excellent regioselectivity (only one regioisomer formed). Full details of catalyst development studies, catalyst loading investigations, substrate scope exploration, protocol innovations (including double in situ ketene generation for 7 examples), and an application to a cinnabaramide A intermediate are described. The addition of lithium perchlorate (1-2 equiv) as an additive to the alkaloid catalyst system was found to favor formation of the E-isomer of the ketene heterodimer. 10 examples were formed with moderate to excellent E-olefin isomer selectivity (74:25 to 97:3) and with excellent enantioselectivity (84-98% ee).

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations

et al. 2016

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“…46 The commercially available reagents (hexamethylbenzene and trifluoromethane-sulfonic acid) were purchased with the best available purity and used without further purification. Benzonitrile (PhCN) was purchased with the best available purity from Wako Pure Chemical Industries, Ltd. and dried according to literature procedures 47 and distilled under Ar prior to use.…”

Section: ▪ Experimental Sectionmentioning

confidence: 99%

Photocatalytic Oxygenation of Substrates by Dioxygen with Protonated Manganese(III) Corrolazine

et al. 2016

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UV-vis spectral titrations of a manganese(III) corrolazine complex [MnIII(TBP8Cz): TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato3−] with HOTf in benzonitrile (PhCN) indicate mono- and diprotonation of MnIII(TBP8Cz) to give MnIII(OTf)(TBP8Cz(H)) and [MnIII(OTf)(H2O)(TBP8Cz(H)2)][OTf] with the protonation constants of 9.0 × 106 M−1 and 4.7 × 103 M−1, respectively. The protonated site of MnIII(OTf)(TBP8Cz(H)) and [MnIII(OTf)(H2O)-(TBP8Cz(H)2)][OTf] were identified by X-ray crystal structures of the mono- and diprotonated complexes. In the presence of HOTf, the monoprotonated manganese(III) corrolazine complex [MnIII(OTf)(TBP8Cz(H))] acts as an efficient photocatalytic catalyst for the oxidation of hexamethylbenzene and thioanisole by O2 to the corresponding alcohol and sulfoxide with 563 and 902 TON, respectively. Femtosecond laser flash photolysis measurements of MnIII(OTf)(TBP8Cz(H)) and [MnIII(OTf)(H2O)(TBP8Cz(H)2)][OTf] in the presence of O2 revealed the formation of a tripquintet excited state, which was rapidly converted to a tripseptet excited state. The tripseptet excited state of MnIII(OTf)(TBP8Cz(H)) reacted with O2 with a diffusion-limited rate constant to produce the putative MnIV(O2•−)(OTf)(TBP8Cz(H)), whereas the tripseptet excited state of [MnIII(OTf)(H2O)(TBP8Cz(H)2)][OTf] exhibited no reactivity toward O2. In the presence of HOTf, MnV(O)(TBP8Cz) can oxidize not only HMB but also mesitylene to the corresponding alcohols, accompanied by regeneration of MnIII(OTf)(TBP8Cz(H)). This thermal reaction was examined for a kinetic isotope effect, and essentially no KIE (1.1) was observed for the oxidation of mesitylene-d12, suggesting a proton-coupled electron transfer (PCET) mechanism is operative in this case. Thus, the monoprotonated manganese(III) corrolazine complex, MnIII(OTf)(TBP8Cz(H)), acts as an efficient photocatalytic for the oxidation of HMB by O2 to the alcohol.

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“…Organic solvents were purified and dried before use by standard methods [16]. Conductance was measured with a Hanna (HI-8633) conductivity meter (Romania).…”

Section: Methodsmentioning

confidence: 99%

Chemistry and antioxidant properties of titanium(IV) complexes

Shaikh

Ashiq

Jamal

et al. 2015

Transition Met Chem

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The synthesis of titanium(IV) complexes with biologically active hydrazide ligands has been carried out. The complexes were characterized by spectroscopic methods (IR, 1 H NMR and 13 C NMR), elemental analysis and conductivity studies. These studies suggest bidentate coordination of the ligands through carbonyl oxygen and primary amine nitrogen, resulting in octahedral geometries. Hydrazides with pyridyl substituents displayed 1:2 metalto-ligand ratio, and hydrazides with imino substituents exhibited 1:3 metal-to-ligand ratio resulting in an outer sphere complex. The remaining complexes displayed inner sphere coordination with 1:1 metal-to-ligand ratio. These complexes exhibit varying degrees of radical scavenging properties against DPPH, superoxide and nitric oxide free radicals. The free ligands showed inhibition against DPPH but were inactive against superoxide and nitric oxide free radicals. The structure-activity relationships of the complexes are discussed.

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Purification of Organic Chemicals

Cited by 207 publications

References 0 publications

Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations

Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations

Photocatalytic Oxygenation of Substrates by Dioxygen with Protonated Manganese(III) Corrolazine

Chemistry and antioxidant properties of titanium(IV) complexes

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