Triethylamine hydrobromide

A colorless precipitate of triethylamine hydrobromide is formed immediately. The temperature rises to about 35°. 

Treatment of 2-benzoylpyridine 81 with p-toluene-sulfonamide gave 1-amino-2-benzoylpyridinium tosylate 82 (X = OTs), which was cyclized with formamide in the presence of triethylamine hydrobromide to give 83 (82FRP2486942). The reaction of the perchlorate 82 (X = C104) with urea in polyphosphoric acid afforded 3-hydroxy-l-phenylpyrido[2,l-/][l,2,4]triazinium perchlorate 84. Treatment of this salt with base led to the zwitterionic l-phenylpyrido[2,l-/][l,2,4]triazin-5-ium-3-olate 85 (86JHC375). Pharmaceutical compositions contain 83 (82FRP2486942). 

B. A -Butenolide. In a 500-ml. three-necked flask fitted with a mechanical stirrer, a reflux condenser, and a 250-ml. dropping funnel containing a solution of 61 g. (84.5 ml., 0.6 mole) of triethylamine in 70 ml. of dry diethyl ether, a solution of 83 g. (0.5 mole) of a-bromo-Y-butyrolactone and 200 ml. of dry diethyl ether is heated to reflux, with stirring. The amine solution is added, slowly, during 5 hours and the stirring under reflux continued for an additional 24 hours. The brown precipitate (40 g.) is removed by filtration. Most of the solvent is removed from the filtrate by evaporation, and the additional precipitate (8 g.) is removed. This precipitate is predominantly triethylamine hydrobromide. The liquid residue is distilled under reduced pressure and the -butenolide is collected at 107-109° (24 mm.) ... 

Despite the fact that aryl bromides are generally less reactive, o- and p-bromotoluenes could be efficiently vinylated with ethene in DMF/H2O with [Pd(OAc)2] + P(o-tolyl)3 as catalyst and Et3N as base [16]. With careful choice of reaction parameters (90 °C and 6 bar of ethene) all bromotoluene was converted to high purity ortho- or para-vinyltoluene. Under the conditions used, the reaction mixture forms two phases. In this case the main role of water is probably the dissolution of triethylamine hydrobromide which otherwise precipitates from a purely organic reaction medium and causes mechanical problems with stirring. 

After about 45 minutes the triethylamine hydrobromide began to precipitate. 

The triethylamine hydrobromide precipitate is filtered and washed with two 60-mL portions of diethyl ether. The filtrate is washed with three 30-mL portions of 5% hydrochloric acid to remove unreacted triethylamine, and then washed with 25 mL of cold water (Note 8), dried over anhydrous magnesium sulfate, and filtered. 

Triethylamine (1 g, 9.9 mmol) was added to a benzene solution of triphenylbismuth dibromide (1.2 g, 2 mmol) and ethylthioacetic acid (1.2 g, 5 mmol). After stirring for 1 h, the precipitated triethylamine hydrobromide was filtered off, and the filtrate was evaporated. The residue was recrystallized from acetonitrile to obtain the corresponding dicarboxylate (m.p. 119°C) [75JINC(37)2559]. 

In a 100 mL round-bottomed flask, prepare a solution of aza[18]crown-6, 17, (3.6 g, 15.2 mmol) and triethylamine (4.2 mL, 3.0 g, 30 mmol) in dry diethyl ether (25 mL) at room temperature. Dissolve cinnamyl bromide (3.0 g, 15.2 mmol) in dry diethyl ether (30 mL), add it slowly to the stirred azacrown solution and fit a calcium chloride guard tube (or alternatively run the reaction under an inert atmosphere). Triethylamine hydrobromide precipitation occurs almost immediately however, it is worth stirring the mixture for several hours more to ensure complete reaction. Remove 50 per cent of the solvent by rotary evaporation, wash with aqueous potassium carbonate (25 mL, 2 m solution) and dry over magnesium... 

Ethyl 3,5-bis(bromomethyl)-4-hydroxybenzoate (0.50 g, 14 mmol) in dichloro-methane (4 mL) was added dropwise to N-(2-pyridylmethyl)-2-aminoethanol (0.43 g, 28 mmol) and triethylamine (0.80 g) in tetrahydrofurane (4 mL) at 0 °C. The resulting yellow solution was stirred for 48 h and monitored with TLC, filtered to remove the white precipitate of triethylamine hydrobromide and the solvent removed under vacuum. The resulting brown oil was purified by flash column chromatography (ethyl acetate/methanol, 8 2,12 stain, Rf = 0.44) to yield a yellow oil (0.50 g, 72.2 %). 

To a solution of 2-methoxy-N-(pyridin-2-ylmethyl)aminoethanol (0.925 g, 5.6 mmol) and triethylamine (1.25 g) in tetrahydrofuran (10 mL) was added dropwise a solution of 4-bromo-2,6-bis(bromomethyl)phenol (1 g, 2.7 mmol) in dichloromethane (10 mL) at 0 °C. The reaction mixture was stirred for 72 h and filtered to remove the precipitate of triethylamine hydrobromide. Removal of the solvent resulted in a yellow oil which was further purified by flash column chromatography (1 g crude ligand, length = 30 cm, diameter = 1.5 cm, ethyl acetate (until firsthand is eluted) then methanol/ethyl acetate 1 5, FeCla stain, Rf = 0.55 in ethyl acetate). The ligand was obtained as a yellow oil (930 mg, 63 %). 

Crude 2 (0.94 g, 1.43 mmol) is dried under vacuum for 30 min and dissolved in anhydrous toluene (4 mL). Triethylamine (0.22 g, 0.3 mL) is added followed by dibenzyl phosphate (0.60 g, to form 1.5 equiv. of triethylammonium dibenzyl phosphate) and the flask is capped with a rubber septum. Triethylamine hydrobromide immediately begins to precipitate. The heterogeneous mixture is stirred at room temperature for 3 h, filtered, and the solid is washed with a small amount of toluene (1-2 mL). The filtrate is concentrated at 25°C. The residue, which shows two main spots by TLC (/ f 0.24 and 0.16,9 1 toluene-LtOAc) is chromatographed, with 13 1 0.1 toluene-LtOAc-LtsN as eluent. Tractions of 0.24 (0.68 g) contain a syrupy mixture of the unstable dibenzyl 2,3,5,6-tetra-O-benzoyl-P-D-galactofuranosyl phosphate (4), and mainly product of its hydrolysis 2,3,5,6-tetra-0-benzoyl-a,P-D-galactofuranose (7), as shown by C NMR spectroscopy. 

---