Tetra-w-butylammonium bromide

Since the amount of solvent in the anode compartment is slowly depleted as the electrolysis proceeds, it is convenient to begin the electrolysis with the level of solution in the anode compartment about 9 cm. above the level of the solution in the cathode compartment. Alternatively, additional 0.2M tetra-w-butylammonium bromide in N,N-dimethylformamide may be added to the anode compartment as the electrolysis proceeds. 

Measured enthalpies of solution of tetra-n-butylammonium bromide (Bu NBr) in mixtures of water (W) with acetonitrile (ACN) and with ethylene carbonate (EC) are compared with those in mixtures of water with some other aprotic solvents which were reported earlier. The results can be fairly well described by an equation which can be derived either from a cooperative hydration model or from a chemical, pseudo equilibrium model. This equation is tested by varying systematically the nature of the solute and of the cosolvent. In order to describe the experimental results in W-ACN and in W-EC as such, it will be necessary to extend the equation with a term which comprises any specific (nonhydrophobic) interactions of the solute with the (inert) cosolvent. 

Tetra- -butylammonium tetrafluoroborate [429-42-5] M 329.3, m 161.8 , 161-163 , pK -4.9 (for HBF4). Recrystallise it from H2O, aqueous EtOH or from EtOAc by cooling in Dry-ice. Also recrystallise it from ethyl acetate/pentane or dry acetonitrile. Dry it at 80° under vacuum, petty Jones JAm Chem Soc 109 5666 1987, Hartley Fairlkner JA/w Chem Soc 107 3436 1985The acetate has m 118 2° (from BuCl), the bromide has m 118° (from EPAc), and the nitrate has m 120° (from C6H ). [Witschonka Kraus J Am Chem Soc 69 2472 1947, Wheeler Sandstedt JAm Chem Soc 77 2024 1955, Beilstein 4IV 558.]... 

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