A New Recyclable Ditribromide Reagent for Efficient Bromination under Solvent Free Condition

Abstract

1,2-Dipyridiniumditribromide-ethane (DPTBE) has been synthesized and explored as a new efficient brominating agent. The crystalline ditribromide reagent is stable for months and acts as a safe source of bromine requiring just 0.5 equiv for complete bromination. It has high active bromine content per molecule and shows a remarkable reactivity compared to other tribromide reagents toward various substrates by just grinding the reagent and substrates in a porcelain mortar at room temperature. No organic solvent has been used during any stage of the reaction for substrates giving product as solid. Product can easily be isolated by just washing the highly water soluble 1,2-dipyridiniumdibromide-ethane (DPDBE) from the brominated product. The spent reagent can be recovered, regenerated, and reused without any significant loss.

Silica-supported quinolinium tribromide: a recoverable solid brominating reagent for regioselective monobromination of aromatic amines

“…or poly(N-bromobenzene-1,3-disulfonylamide), 13 1,2-dipyridiniumditribromide-ethane, 14 ethylenebis(Nmethylimidazolium) ditribromide, 15 1-butyl-3-methylpyridinium tribromide, 16 tert-butylhydroperoxide/ HBr, 17 LiBr/(NH 4 ) 2 Ce(NO 3 ) 6 , 18 KBr/NaBO 3 ·4H 2 O, 19 2 -m e t h y l -4 -p o l y ( s t y r y l m e t h y l ) t h i a z o l i u m hydrotribromide, 20 LiBr/(diacetoxyiodo)benzene, 21 alkalimetal bromide/NaIO 4 , 22 bromodimethylsulfonium bromide, 23 HBr/H 2 O 2 , 24 1,8-diazabicyclo [5.4.0]undec-7-ene hydrobromide perbromide, 25 metal bromides/ sodium bismuthate, 26 N-octyl quinolinium tribromide 27 and pyridinium hydrobromide perbromide. 28 However, some methods still suffer from drawbacks of difficult handling, low selectivity, low yield and corrosion.…”

In Search of Simplicity and Flexibility: A Rational Access to Twelve Fluoroindolecarboxylic Acids

“…40-42°C (ref. [73] 41-42°C); yield: 3.61 g (76 %). 1 H NMR: δ = 7.14 (dd, J = 10.7, 2.1 Hz, 1 H), 7.05 (ddd, J = 9.1, 0.9, 0.4 Hz, 1 H), 6.66 (t, J = 8.9 Hz, 1 H) ppm.…”

Solvent-Free Dibrominations of Alkenes and -Unsaturated Carbonyl Compounds using Cetyltrimethyl Ammonium Tribromide

“…Moreover, bromo compounds are important as intermediates in synthesis of organometallic compounds, in transition metal coupling reactions and as intermediates in various other organic transformations [4][5][6] . In this regard the quaternary ammonium tribromides (QATB) have become quite popular as reagents [7][8][9][10][11][12][13][14][15] . Our experience with QATB reagents reveal that these reagents are easy to handle, have prolonged shelf-life, maintain desired stoichiometry and are very versatile, capable of allowing a variety of organic transformations.…”