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Volumn 48, Issue 18, 2007, Pages 3247-3250

Contrasting chemoselectivities in the ultrasound and microwave assisted bromination reactions of substituted alkylaromatics with N-bromosuccinimide

Author keywords

Bromination; Microwave; N Bromosuccinimide; Ultrasound

Indexed keywords

BROMINATED HYDROCARBON; HYDROCARBON; N BROMOSUCCINIMIDE; WATER;

EID: 34047184163     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2007.03.023     Document Type: Article
Times cited : (39)

References (27)
  • 3
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    • Loupy A. (Ed), Wiley-VCH, Weinheim November
    • In: Loupy A. (Ed). Microwaves in Organic Synthesis (2006), Wiley-VCH, Weinheim November
    • (2006) Microwaves in Organic Synthesis
  • 5
    • 0141878086 scopus 로고    scopus 로고
    • Lidström P., and Tierney J.P. (Eds), Blackwell, Oxford
    • In: Lidström P., and Tierney J.P. (Eds). Microwave-Assisted Organic Synthesis (2004), Blackwell, Oxford
    • (2004) Microwave-Assisted Organic Synthesis
  • 6
    • 85013109369 scopus 로고    scopus 로고
    • Kappe C.O., and Stadler A. (Eds), Wiley-VCH, Weinheim
    • In: Kappe C.O., and Stadler A. (Eds). Microwaves in Organic and Medicinal Chemistry (2005), Wiley-VCH, Weinheim
    • (2005) Microwaves in Organic and Medicinal Chemistry
  • 18
    • 34047181334 scopus 로고    scopus 로고
    • 4 and analysed by GC and GC-MS. For the NMR samples the solvent was evaporated prior to analysis. The comparative thermal reactions were carried out in 15 ml water at 90 °C for 40 min using the same reagent amounts as in the ultrasound reactions. The work-up and analysis of the reaction mixtures was as described above for the ultrasound assisted reactions.
  • 19
    • 34047140874 scopus 로고    scopus 로고
    • Microwave-promoted experiments were carried out in the dark with a CEM Discover 300 W single mode microwave instrument. For the reactions without water, the closed vessels used were special glass tubes with self-sealing septa that controlled pressure with appropriate sensors on the top (outside the vial). The initial power was 200 W and when the preselected temperature was obtained it was automatically adjusted to maintain this temperature. The temperature was monitored through a non-contact infrared sensor centrally located beneath the cavity floor. Magnetic stirring was provided to assure complete mixing of the reactants. Under these conditions the pressure in the tubes never exceeded 4 bar. The 10 ml reaction vessels were charged in air with 0.32 g (3.0 mmol) of o-xylene and 0.54 g (3.0 mmol) of NBS. After the microwave irradiation was finished, the reaction mixture was cooled rapidly. The work-up and analysis was as described above for the ultrasound assisted reactions. When water (15 ml) was used, the microwave experiments were carried out in a 100 ml round-bottomed three-neck flask equipped with a magnet and a reflux condenser open to the air. The reaction vessel was submitted to microwave irradiation for 40 min in the cavity where the power (initially 100 W) was self-adjusted to maintain 90 °C. The quantities of reagents were the same as above. When the reaction time was reached, the mixture was cooled rapidly to rt. Work-up and analysis was as described above for the ultrasound assisted reactions.


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