Benzyltrimethylammonium bromide

In order to isolate adipic acid, nylon-6,6 fibers were depolymerized under reflux with a 50% NaOH solution in the presence of catalytic amounts of benzyltrimethylammonium bromide. The oligomers formed in successive steps were depolymerized under similar conditions. The yields in steps 1, 2, and 3 were... 

A 500 mL round-bottom flask containing aqueous sodium hydroxide (25 or 50 wt%) and benzyltrimethylammonium bromide as the phase transfer agent (0.2 g, 0.0008 mole) was placed in a constant-temperature oil bath and heated to the reflux temperature of 165°C. Chopped nylon-4,6 fibers (6 g, 0.030 mol) were placed in the reaction flask. The reaction mixture was constantly stirred with a magnetic stirrer and the reaction was carried out at atmospheric pressure for a period of 24 or 36 h (see Table 10.3 for results). The aqueous sodium hydroxide solution containing products of depolymerization was concentrated by evaporation and 30 mL of 35% aqueous hydrochloric acid was added to the concentrate. The precipitate was filtered and washed with water. The product was dried in a vacuum oven at 120°C for 24 h. 

The benzyltrimethylammonium bromide formed in this step returns to the aqueous phase, where it can repeat the cycle. 

Solutes. Toluene, although polarizable, was chosen as an apolar solute. Caffeine was chosen as a polar but nonionic solute. Four ionic solutes were tested benzyltrimethylammonium bromide (BTAB) is a cationic quaternary ammonium salt. Benzoic acid acts as an anionic solute at mobile phase pH values between 5.5 and 6.5 (the pK lies between 3.7 in CTAB solutions and 4.7 in SDS solutions)(4). Sodium paraoctylbenzene sulfonate (SOBS) (pK -0.8) and cetylpyridinium chloride (CPC) were chosen as ionic solutes having surfactant properties. Their hydrophobic "tails have the same lenghts as those of SDS and CTAB, respectively. 

The benzyltrimethylammonium ion migrates to the butyl bromide phase, carrying a cyanide ion along with it. Once in the organic phase, cyanide ion is only weakly solvated and is far more reactive than it is in water or ethanol, where it is strongly solvated by hydrogen bonding. Nucleophilic substitution takes place rapidly. The benzyltrimethylammonium bromide formed in the substitution step returns to the aqueous phase, where it can repeat the cycle. 

Improved procedures have been reported for the conversion of aliphatic or aromatic aldehydes into 1-bromoacetylenes with one extra carbon atom (carbon tetrabromide, triphenylphosphine, and benzyltrimethylammonium bromide), and for the preparation of 1-chloroacetylenes from the corresponding terminal acetylenes (n-butyl-lithium and iV-chlorosuccinimide). ... 

Scheme 1-266. Benzyltrimethylammonium bromide [l,2]-rearrangement in diethyl ether, but [3,2]-rearrangement in ammonia.

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