3
temperature under aerobic condition. The progress of the reaction
peroxide as oxidant and Mont K-10 supported AgNPs as catalyst.
Due to mild reaction conditions our method has the advantage of
broad functional group compatibility for both electron-rich and
electron poor substituents. In addition to this, ligand, base and
solvent-free condition as well as short reaction time make this
methodology quite attractive with promise of future applications.
was monitored by TLC. After the completion of the reaction, the solid
was separated by filtration, extracted with diethyl ether. The combined
organic layers were dried over by anhydrous Na2SO4 and evaporated in
a rotary evaporator under reduced pressure. The crude was purified by
column chromatography on silica gel (hexane: ethyl acetate, 9:1) to
afford the desired product. The purity of the compound was confirmed
by 1H NMR, GC-MS and FT-IR.
Acknowledgements
We gratefully thank UGC, New Delhi (India) for financial
support (No.41-254/2012 (SR). T. Begum is thankful to UGC,
New Delhi for financial assistance in the form of UGC-BSR
(RFSMS) Fellowship.
References and notes
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17. Synthesis of silver nanoparticles:
2 ml of the leaf extract
(Phlogacanthus thyrsiformis) was added to 20 ml of 0.01 M AgNO3
solution and kept for 2-3 minutes at room temperature before stirring
for 4 hours. The color of the reaction mixture was found to change
from colorless to a transparent yellow and finally to a dark brown
solution, attributing the reduction of Ag+ to Ag0. The resulting solution
was centrifuged and the nanoparticles were collected for
characterization (see the supporting information)
18. Preparation of montmorillonite clay supported AgNP catalyst: The
formed AgNPs were suspended in 30 ml of distilled water and
ultrasonicated for about 15 minutes. To the silver nano suspension 500
mg of mont K-10 clay was added, and then stirred for 24 hours at room
temperature. The formed precipitate was filtered and collected over a
round dish. Then it was heated at 110 °C for 3 h under oven followed
by calcinations at 400 °C for 4 hour in a silica crucible in furnace, and
then stored under moisture-free condition and characterized (see the
supporting information). ICP-AES analysis indicated loading of 0.225
mg of AgNP in per 20 mg of Montmorillonite.
19. Gogoi, P. K.; Begum, T.; Borthakur, B.; Das, G.; Bora, U.; Kumar, A.
National Academy Science Letters (in press).
20. General procedure for the hydroxylation of arylboronic acid: A 50 mL
round bottom flask was charged with arylboronic acid (1 mmol), 30%
aqueous H2O2 (0.5 mL) and 5 mg of Ag-mont K-10 without using any
solvent system and the reaction mixture was stirred at room