Direct bromination of hydrocarbons catalyzed by Li2MnO3 under oxygen and photo-irradiation conditions

Nishina, Yuta; Morita, Junya; Ohtani, Bunsho

doi:10.1039/c2ra22197g

Cited by 16 publications

(10 citation statements)

References 38 publications

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“…Although Br 2 [13], CBr 4 [18–20], R 4 NBr [21–22] and LiBr [23] have been reported to serve as bromine sources for the bromination of saturated hydrocarbons, these reactions exhibit low selectivity or reactivity. Efficient bromination using Br 2 as a bromine source combined with a stoichiometric base [24], an excess of MnO 2 [25], or a catalytic amount of Li 2 MnO 3 [26] has been reported to give high reactivity and selectivity. The combination of CBr 4 with a copper catalyst at high temperature also achieves effective bromination of hydrocarbons [27].…”

Section: Introductionmentioning

confidence: 99%

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

Nishina¹,

Ohtani²,

Kikushima³

2013

Beilstein J. Org. Chem.

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SummaryThe bromination of hydrocarbons with CBr4 as a bromine source, induced by light-emitting diode (LED) irradiation, has been developed. Monobromides were synthesized with high efficiency without the need for any additives, catalysts, heating, or inert conditions. Action and absorption spectra suggest that CBr4 absorbs light to give active species for the bromination. The generation of CHBr3 was confirmed by NMR spectroscopy and GC–MS spectrometry analysis, indicating that the present bromination involves the homolytic cleavage of a C–Br bond in CBr4 followed by radical abstraction of a hydrogen atom from a hydrocarbon.

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Section: Introductionmentioning

confidence: 99%

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

Nishina¹,

Ohtani²,

Kikushima³

2013

Beilstein J. Org. Chem.

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“…Method of Analysis. 1 H and 13 C NMR were recorded in solvent CDCl 3 with tetramethylsilane as the internal standard using Agilent 400 MHz NMR. Fourier-transform infrared (FT-IR) spectra were recorded using a Bruker TENSOR II FT-IR Spectrometer.…”

Section: Methodsmentioning

confidence: 99%

“…13 Nishina et al 13 studied bromination of saturated cyclic compounds using Br 2 as well as NBS with Li 2 MnO 3 as a photocatalyst. 13 Wang et al 14 studied in depth the photothermal radical bromination and dehydrobromination of saturated long-chain alkanes. Dehydrobromination was performed readily at temperatures between 175 and 190 °C without any catalyst.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Unsaturated Drying Oils from Saturated Fatty Oils Derived from Renewable Feedstocks

Sancheti

Jain

Jindani

et al. 2020

Ind. Eng. Chem. Res.

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Surface coating industry uses drying and semi-drying oils containing varying amounts of oleic, linoleic, and linolenic fatty acids or dehydrated ricinoleic acid (castor oil) fractions (with iodine values in the range of 125–160 g/100 g) for manufacturing alkyd resins. These are used in large volumes in air drying paints and varnishes. Different methods are reported in the literature for increasing the unsaturation in the available fatty oils/acids. Most of these methods use feedstocks that already contain unsaturation. In this research, we studied functionalization of renewable saturated oils (iodine value ≤ 5 g/100 g) as potential replacements for costly unsaturated vegetable oils such as soybean oil, linseed oil, castor oil, and so forth. This process includes radical bromination of saturated fatty acids/oils followed by dehydrobromination using an alcoholic base to obtain the desired unsaturation. Computational studies were performed to find out stability of bromo compounds. Dehydrobromination was found to be quantitative when fully saturated feedstocks were employed. On the other hand, feedstocks bearing unsaturation could not be fully dehydrobrominated, demonstrating thereby that the approach adopted herein is ideally suited to completely saturated oil as a replacement. The maximum achieved iodine value was 125–130 g/100 g for 1:3 ratio of [substrate]/[Br]. Performance tests were carried out on the product, and the results were found to be along expected lines with commercial products. Further increase of the iodine value to 132 g/100 g was achieved by separating out the unreacted saturates by crystallization. In this way, product efficacy could be enhanced while recycling the saturated fraction in a subsequent batch. Separation of saturated components from unsaturated components would also be beneficial for successful use of inexpensive feedstocks such as tallow. It is further shown that the brominating reagent and catalyst can be recycled and reused, making the whole process industrially attractive.

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“…In 2013, Nishina and co-workers reported mono-bromination of hydrocarbons [ 30 ]. In the reaction, starting substances reacted with Br 2 in the presence of Li 2 MnO 3 as a photocatalyst under irradiation of fluorescent light under O 2 pressure to give brominated products ( Scheme 10 ).…”

Section: Photo-catalyzed Halogenation Of Aliphatic C-h Bondsmentioning

confidence: 99%

Visible-Light-Induced Catalytic Selective Halogenation with Photocatalyst

2021

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Halide moieties are essential structures of compounds in organic chemistry due to their popularity and wide applications in many fields such as natural compounds, agrochemicals, and pharmaceuticals. Thus, many methods have been developed to introduce halides into various organic molecules. Recently, visible-light-driven reactions have emerged as useful methods of organic synthesis. Particularly, halogenation strategies using visible light have significantly improved the reaction efficiency and reduced toxicity, as well as promoted reactions under mild conditions. In this review, we have summarized recent studies in visible-light-mediated halogenation (chlorination, bromination, and iodination) with photocatalysts.

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Direct bromination of hydrocarbons catalyzed by Li2MnO3 under oxygen and photo-irradiation conditions

Cited by 16 publications

References 38 publications

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

Synthesis of Unsaturated Drying Oils from Saturated Fatty Oils Derived from Renewable Feedstocks

Visible-Light-Induced Catalytic Selective Halogenation with Photocatalyst

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Direct bromination of hydrocarbons catalyzed by Li2MnO3 under oxygen and photo-irradiation conditions

Cited by 16 publications

References 38 publications

Bromination of hydrocarbons with CBr4, initiated by light-emitting diode irradiation

Bromination of hydrocarbons with CBr4, initiated by light-emitting diode irradiation

Synthesis of Unsaturated Drying Oils from Saturated Fatty Oils Derived from Renewable Feedstocks

Visible-Light-Induced Catalytic Selective Halogenation with Photocatalyst

Contact Info

Product

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Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation