tetraniethylammonium ion would indicate a reversible reaction. Blue “schlieren,” typical of the alkali metals, are formed during the electrolysis of tetramethyl- and tetraethylammonium iodides in liquid ammonia. This might indicate that the neutral quatcrnary configuration dissociates into a cation and a n electron. Wheland (17) has suggested that this electron is probably a “conductivity” electron since there is no orbit around the nitrogen to contain it. An aromatic quatwnary reduction may be initiated in the same manner as a n aliphatic reduction-that is, by the reversible acquisition of a n electron. Since the start of the wave is not pI-1 dependent, hydrogen ion is probably not involved in the first step of the electrolysis. Several reactions are possible folloning the acquisition of a n electron.
It is difficult to assess the relative role of each of the above reactions in the over-all situation. Experimentally, i t has been observed t h a t the titer of the electrolyzed quaternary hydroxide solution decreases by a n amount equal to the ameunt of amine produced. A trace of peroxide can be detected, with most of this compound having been destroyed by Reaction 10 or 11. Any hydrogen produced could come from Reaction 5, 8, 13, or 14. Oxygen is produced a t the anode and also by Reaction 10. The cathodic reaction may occur a t the platinum wire connecting the mercury pool to the power supply as well as a t the mercury-water interface. Some explanation is possible for the range of current efficiencies with respect to the production of amine. (Current efficiency is here defined as the amine 21 2
ANALYTICAL CHEMISTRY
produced divided by the quantity of electricity times 100.) The highest efficiency, 54%, was found in the electrolysis of benzyldimethylanilinium hydroxide. The p H during this electrolysis was about 13. It was found that a t this pH dimethylaniline cannot cause a catalytic hydrogen wave until the cathode potential reaches about -2.2 volts. Since the potential during this elpctrolysis never became more negative than -2.0 volts, Reaction 13 could not interfere with Reaction 4. If the amine produced by the electrolysis can catalyze a hydrogm n-are, the current efficiency drops. The electrolysis of benzyltributylnnimonium hydroxide proceeded with cfficicncics of 23 t o 35%. A different situation exiqts during the electrolysis of benzyltriniethylamnionium hydroxide. Thc amine (trimethylamine) can catalyze a hydrogm wave but i t is volatile. The current efficiency varies with the rate of purge (23 to 42.57,). The effect of these reactions occurring within the confines of the capillary of a dropping mercury electrode can well be imagined. The current level of an aliphatic-type reaction (Figure 1, A and B ) is considerably enhanced by the regeneration of the starting material via Reactions 1 and 2. I n the extremely limited space between the walls of the capillary and the mercury column, diffusion away from the electrode surface is practically impossible. The effect of this phenomenon on the polarogram of a Type I aromatic quaternary compound is even more pronounced. S o t only can the reaction be enhanced by the same mechanism as indicated for a n aliphatic-type rcduction, but the additional effects of a catalytic amine wave and the rpduction of peroxide must be considered. The current level (Figure 1, D)for a polarogram of a Type I aromatic quaternary compound is about 10 times that of a n aliphatic-type compound and about 40 times t h a t of a normal quaternary polarogram. It is obvious t h a t mathematical treatment of the polarographic behavior of a n aliphatic or Type I aromatic quaternary ammonium compound would be extremely difficult if not impossible. The primary difficulty is the lack of any means to define the electrode area. h’ot only is the drop irregular and turbulent (the solution in the vicinity of the drop is stirred) b u t the reaction occurs 1 to 2 em. up inside the capillary. The problem would be further complicated by the necessity of a treatment of diffusion within a limited space. For the same reasons as given above, any reasonable polarographic procedures for the determination of quaternary ammonium compounds need to be limited to Types I1 and I11 aromatic compounds.
LITERATURE CITED
(1) Emmert, B., Ber. deut. chem. Ges. 42, 1507 (1909). (2) Ibid., p. 1997. (3) Ibid., 45, 430 (1912). (4) Finkelstein, M., Petersen, R. C., Ross, S. D., J . Am. Chem. SOC.81, 2361 (195‘3). ( 5 ) Grahame, D. C., Ibid., 63,1207 (1941). (6) Iofa, Z. A., Frumkin, A. N., Maznichenka, E. k,Zhur. ‘ F i z . Khim. 31, 2042 (1957). (7) Kolthoff, I. ?,I., Lingane, J. J., “Polarography,” 2nd ed., p . 770, Interscience, New York, 1952. (8) Ibid., p. 815. (9) ;\IcCoy, H. N., Moore, IT-. C., J . A m . Chem. SOC. 33, 273 (191 1). (10) RlcCoy, H. N., West, F. L., J . Phys Chem. 16, 261 (1912). (11) Schluback, H. H., Ber. deut. chein Ges. 53, 1689 (1920). (12) Schluback, H. H., Ballauf, F., I b i d . 54, 2811 (1921). (13) Smith, G. McP., J . drn. Chem. SOC. 29, 844 (1907). (14) van Rysselberghe, P., &Gee, J. XI., Ibid., 67, 1039 (1945). (15) Vleck, A. 9., Chem. listy 47, 1669 (1953). (16) von Stackelberg, M., Stracke, W., 2. Elektrochem. 53, 118 (1949). (17) Wheland, G. W., “Advanced Organic Chemistry,” 2nd ed., p. 739, Wile!., Kew York, 1949. RECEIVEDfor review July 25, 1960. Accepted Sovember 10, 1960. Abstracted from thesis presented to Graduate School of Rensselaer Polytechnic Institute by Burnett C. Southvorth in partial fulfillment of the requirements for the degree of doctor of philosophy.
Correction Determination of Ethylene and Propylene Glycol in Mixtures by Gas Chromatogra phy I n this article by H. G. Kadeau and D. M. Oaks [ANAL. CHEM.32, 1760 (196O)l on page 1762 under Discussion of Results the sentence “The order of elution is N P G to MEG, whence it can be reasoned that the hydroxy groups in 1IPG are separated by one more carbon atom than t h a t for MEG, giving rise to weaker hydrogen bonding, and vice versa for MEG.” should be changed to “The order of elution is MPG to AIEG, nhence, i t can be reasoned that the separation is in accord with the respective boiling points. This also must mean t h a t a difference in hydrogen bonding exists, which would indicate AIEG to be more polar.”
