The Use of Cationic Surfactants in Electrochemistry and Catalysis on

8

Inorganic Reactions in Organized Media Downloaded from pubs.acs.org by UNIV OF CALIFORNIA SANTA BARBARA on 09/18/15. For personal use only.

T h e U s e of C a t i o n i c Surfactants i n Electrochemistry and C a t a l y s i s on P l a t i n u m THOMAS C. FRANKLIN, MAURICE IWUNZE, and STEPHEN GIPSON Baylor University, Chemistry Department, Waco, TX 76798 The addition of cationic surfactants, especially Hyamine 2389 (predominantly methyldodecylbenzyl trimethylammonium chloride) to aqueous systems has been shown to increase yields in electrolytic synthesis studies, to make possible voltammetric studies of various organic and inorganic compounds using platinum electrodes, and to accelerate the rate of hydrolysis of esters on platinum surfaces. The surfactant accomplishes this by solubilizing the compounds in micelles and by forming a hydrophobic film on the surface of the platinum which excludes water but allows the penetration of the reactants to the surface. The film structure has been indicated to be similar to the structure of an inverted micelle. It is caused by adsorption of chloride ions on the platinum and the attachment of the quaternary ion by ion pairing. One can cause alternating increases and decreases in the rate of electrooxidation and catalytic esterification by the presence of monolayers, bilayers, etc. General Use of Additives Additives have been routinely used in corrosion (1), catalysis (2) and electrodeposition(3,4) ,fields in which metals interface with electrolytic solutions. Studies in these areas are part of the field of modification of metal surfaces in order to change the rates of processes occurring at the surface. In recent years there has been a good deal of work on what is known as chemical modifications of electrodes (5). While these semipermanent modifications have involved some sophisticated investigations, the additive field is largely studied by a trial and error process. The work in our laboratories has been aimed at obtaining an understanding of the role of additives in these 0097-6156/82/0177-0139$05.00/0 © 1982 American Chemical Society

140

INORGANIC REACTIONS IN ORGANIZED MEDIA

p r a c t i c a l processes and i n recent years centrated on c a t i o n i c s u r f a c t a n t s .

t h i s work has con-


C a t i o n i c Surfactant A d d i t i v e s Although a n i o n i c and c a t i o n i c s u r f a c t a n t s have always been t y p i c a l a d d i t i v e s used i n the e m p i r i c a l s t u d i e s , i n r e c e n t years a more i n t e n s i v e look has been taken at the use of these s u r f actaats i n e l e c t r o c h e m i s t r y . Many of these s t u d i e s have concentrated on quaternary s a l t s Ç6-18) and t h e i r use i n o r g a n i c e l e c t r o c h e m i s t r y . These s t u d i e s were i n p a r t stimulated by the development a t Monsanto (1Z) and l a t e r a t P h i l l i p s Petroleum (18) of e l e c t r o l y t i c processes f o r the e l e c t r o h y d r o d i m e r i z a t i o n of a c r y l o n i t r i l e t o make a d i p o n i t r i l e u s i n g quaternary s a l t s as supporting e l e c t r o l y t e s . The research i n e l e c t r o o r g a n i c chemistry has concentrated on the uses of s u r f a c t a n t s to s o l u b i l i z e organic reactants and products i n aqueous e l e c t r o l y t i c s o l u t i o n s . In some cases l a r g e amounts of these h y d r o t r o p i c s a l t s (17,19,20) have been used t o break the water s t r u c t u r e thus i n c r e a s i n g "the s o l u b i l i t y o f the organic compounds. In other cases the s u r f a c t a n t s have been used as e m u l s i f y i n g agents f o r o r g a n i c s o l v e n t s , used to d i s s o l v e the compounds (21-26) . In s t i l l o t h e r cases the compounds have been s o l u b i l i z e d i n the form of m i c e l l e s (27-39). Phase T r a n s f e r and M i c e l l e C a t a l y s i s I t has become i n c r e a s i n g l y evident that the s u r f a c t a n t s are accomplishing more than the s o l u b i l i z a t i o n of the organic compounds. C e r t a i n l y phase t r a n s f e r c a t a l y s i s would be expected t o occur i n the emulsion system and t h i s has been proposed i n s e v e r a l o r g a n i c synthesis s t u d i e s (21-^26). The term m i c e l l e c a t a l y s i s has not been used to any extent i n e l e c t r o c h e m i s t r y . Instead terms such as i o n p a i r i n g and i o n b r i d g i n g have been used t o e x p l a i n the a c c e l e r a t i o n of e l e c t r o d e r e a c t i o n s by the presence o f a v a r i e t y of ions i n the i n t e r f a c e between the s o l u t i o n and the e l e c t r o d e (40-42). Obviously these processes are the same king o f processes one p o s t u l a t e s i n m i c e l l e c a t a l y s i s . The Surfactant F i l m on the Surface of the E l e c t r o d e Studies i n our l a b o r a t o r i e s (43-51) have concentrated on the e f f e c t s of quaternary s a l t s on e l e c t r o c h e m i c a l oxidations on platinum e l e c t r o d e s i n emulsion and m i c e l l e systems. In a d d i t i o n s t u d i e s have been made of the e f f e c t of these s u r f a c t a n t s on a n o n c a t a l y t i c process o c c u r r i n g at the platinum s o l u t i o n i n t e r f a c e . The quaternary s a l t used f o r most o f the experiments was Hyamine 2389 (predominantly methyl dodecylbenzyl t rime thy 1 ammonium c h l o r i d e ) and the aqueous s o l u t i o n was s t r o n g l y b a s i c . Under these conditions i t was concluded (49) that the anode was covered

8.

FRANKLIN E T A L .

141

Use of Cationic Surfactants

w i t h a l a y e r of s t r o n g l y adsorbed c h l o r i d e i o n s . These ions were i o n p a i r e d w i t h the quaternary i o n w i t h the p o s i t i v e head toward the e l e c t r o d e and the nonpolar t a i l toward the aqueous s o l u t i o n . Thus the metal serves as a means of forming an i n v e r t e d m i c e l l e (Figure 1 ) .


Voltammetric

Studies

Voltammetric methods are very u s e f u l f o r studying f a c t o r s that i n f l u e n c e f i l m s on the s u r f a c e o f metals. F i g u r e 2 (44) shows a comparison of anodic c u r r e n t - v o l t a g e curves obtained with platinum e l e c t r o d e s i n aqueous sodium hydroxide. I t can be seen that i n the absence of a s u r f a c t a n t water i s o x i d i z e d a t about 0.7 v o l t s . I f a n i o n i c o r n e u t r a l s u r f a c t a n t s are present there i s l i t t l e s h i f t i n t h i s o x i d a t i o n p o t e n t i a l i n d i c a t i n g that water penetrates r e l a t i v e l y unhindered t o the e l e c t r o d e s u r f a c e . However, when Hyamine 2389 i s added two things are observed. F i r s t , there i s a peak a t about 1.3 v o l t s showing that the Hyamine i s o x i d i z e d . Upon repeated o x i d a t i o n one sees t h i s maximum decrease i n height u n t i l a f t e r 3 or 4 runs one sees a r e l a t i v e l y f l a t r e s i d u a l c u r r e n t l i n e . This behavior i n d i c a t e s that the Hyamine i s o x i d i z e d to form a r e l a t i v e l y f i r m l y bound f i l m which prevents new unoxidized Hyamine from reaching the metal s u r f a c e . In a d d i t i o n one sees that the o x i d a t i o n p o t e n t i a l f o r water i s i n c r e a s e d t o about 2.0 v o l t s . Thus t h i s hydrophobic f i l m has excluded water from the e l e c t r o d e i n t e r f a c e t o such an extent that one must apply 1.3 v o l t s more i n order t o o x i d i z e the water. This hydrophobic behavior i s s i m i l a r t o the behavior expected i n m i c e l l e systems. Oxidation of Organic Compounds on the Filmed

Surface

From a p r a c t i c a l e l e c t r o c h e m i c a l viewpoint the f i l m f u r nishes 1.3 v o l t s more of o x i d i z i n g p o t e n t i a l i n which t o look f o r the o x i d a t i o n o f compounds. Because of t h i s e x t r a p o t e n t i a l range there a r e a number o f compounds that give d i s t i n c t o x i d a t i o n waves i n the presence of the Hyamine that g i v e no wave o r only i n d i s t i n c t waves i n i t s absence. F i g u r e 3 shows a v o l t ammetric curve f o r the o x i d a t i o n o f t h i o u r e a (47). Thiourea gives no observable wave i n the absence o f the s u r f a c t a n t but gives very d i s t i n c t waves i n i t s presence. I t should a l s o be noted that the e l e c t r o c h e m i c a l technique furnishes a method o f studying which substances are e x t r a c t e d by the i n v e r t e d m i c e l l e i n t o the zone o f r e a c t i o n . The three e f f e c t s , i n c r e a s e d s o l u b i l i t y , m i c e l l e c a t a l y s i s , and the increased range of a v a i l a b l e o x i d a t i o n p o t e n t i a l s allows one t o see normally unobserved o x i d a t i o n waves f o r a number o f compounds, a few o f which are l i s t e d i n Table I .


142 INORGANIC REACTIONS IN ORGANIZED MEDIA


8.

FRANKLIN

ET

AL.


143

VOLTAGE (VOLTS) J. Electrochem. Soc.

Figure 2. Effect of different surfactants on the anodic current potential (vs. SCE) curves obtained in 2 Ν NaOH. Key: A, no surfactant; B, anionic surfactant; C, neutral surfactant; and D, cationic surfactant

144



12 ι I

POTENTIAL (VOLTS) J. Electroanal. Chem.

Figure 3. Anodic current-voltage curves in aqueous sodium hydroxide. Key: A, with Hyamine2389; and B, with Hyamine 2389 plus8.76 X 10 M thiourea. s

8.

FRANKLIN

ET AL.

145


Table I Observed Half-Wave P o t e n t i a l s of Some Organic Compounds i n 2N Aqueous Sodium Hydroxide With and Without Hyamine M i c e l l e s


E

Compound ΝADR (51) c y s t e i n e (51) 2 , 4 - d i n i t r o a n i l i n e (48) o-phenylenediamine (48) p ^ n i t r o b e n z o i c a c i d (48) p-nitrobenzaldehyde (48) 2 , 5 - d i c h l o r o a n i l i n e (48) D-glueose (48) biphenyl (48) benzhydrol (48) anthracene (48) p a l m i t i c a c i d (48) m - t o l u i c a c i d (48) p h e n y l s a l i c y l a t e (48) adenine (48) *Abbreviations used:

l/2

With Micelle

Sodium Hydroxide

0.77, 1.15 1.07 0.78, 0.93 0.42, 1.0 0.78 0.77 0.85 0.80 0.86 0.84 0.90 0.96 0.81 1.07 1.11

unobserved unobserved unobserved 0.58, 1.05 unobserved unobserved unobserved unobserved unobserved unobserved unobserved unobserved 0.80(s)* 0.63 (sm) 0.77(s)

s

s s h o u l d e r , sm^small

F i g u r e 4 (48) shows a comparison of o x i d a t i o n p o t e n t i a l s obtained f o r a v a r i e t y o f compounds i n aqueous sodium hydroxide and i n the same s o l u t i o n c o n t a i n i n g Hyamine, i n the form of m i c e l l e s and as an emulsifying agent. I n aqueous s o l u t i o n s o x i d a t i o n s occur p r i m a r i l y around the two p o t e n t i a l s of o x i d a t i o n of platinum (The three h i g h e r o x i d a t i o n p o t e n t i a l s i n the f i g u r e a r e i n the oxygen e v o l u t i o n r e g i o n and probably o x i d a t i o n occurs by oxygen.). The mechanism of o x i d a t i o n on platinum i n aqueous s o l u t i o n s i s g e n e r a l l y accepted t o be e l e c t r o c h e m i c a l o x i d a t i o n of the platinum s u r f a c e followed by a chemical r e a c t i o n of the compound w i t h the s u r f a c e oxides of platinum (52). S i m i l a r l y i n the emulsion system the p o t e n t i a l s a r e grouped around the o x i d a t i o n p o t e n t i a l of Hyamine i n d i c a t i n g a chemical o x i d a t i o n of the compounds by the e l e c t r o l y t i c a l l y o x i d i z e d Hyamine. However, i n the m i c e l l e system t h e o x i d a t i o n s a r e spread over a wide range o f p o t e n t i a l s i n d i c a t i n g d i r e c t e l e c t r o chemical o x i d a t i o n of the compounds. T h i s i s v e r y s i m i l a r t o the r e s u l t s obtained i n nonaqueous s o l u t i o n s , once more showing the hydrophobic nature of the e l e c t r o d e i n t e r f a c e .


146


Figure 4. Comparison of anodic half-wave potentials of different organic compounds obtained in aqueous sodium hydroxide containing A, nothing; B, acetonitrile + Hyamine 2389 (emulsion); and C, Hyamine (micelle). Key: O, anodic half-wave potentials of Hyamine in the micelle system; and J , Anodic half-wave potentials of Hyamine in the emulsion system.

8.

FRANKLIN E T A L .


Electrochemical

147


Synthesis

One o f the primary uses of modified e l e c t r o d e s has been i n the area o f e l e c t r o c h e m i c a l s y n t h e s i s . Again the increased s o l u b i l i z a t i o n by m i c e l l e s and emulsions has been the primary i n t e r e s t i n using c a t i o n i c s u r f a c t a n t s . However, m i c e l l e and phase t r a n s f e r c a t a l y s i s and the hydrophobic nature o f the e l e c t r o d e f i l m has contributed t o i n c r e a s e d y i e l d s . T a b l e I I shows a comparison of y i e l d s obtained i n the e l e c t r o o x i d a t i o n of benzh y d r o l i n the presence o f d i f f e r e n t s u r f a c t a n t s and a comparison of the y i e l d s obtained w i t h s e v e r a l other compounds w i t h and w i t h out Hyamine 2389 (50). I t can be seen that without a s u r f a c t a n t there i s no y i e l d i n aqueous s o l u t i o n s . Anionic and n e u t r a l s u r f a c t a n t s which s o l u b i l i z e the compound but do not f i l m t h e e l e c t r o d e cause only s m a l l i n c r e a s e s i n y i e l d , but the c a t i o n i c f i l m forming s u r f a c t a n t causes a sharp i n c r e a s e i n y i e l d . Table I I The E f f e c t of Surfactant M i c e l l e s on the Y i e l d s Obtained i n E l e c t r o o x i d a t i o n s on Platinum E l e c t r o d e s i n 2N Aqueous Sodium Hydroxide* Type of Y i e l d % w/surfactant Surfactant Product Compound Benzyhydrol(44) Benzyhydrol(44) Benzyhydrol(44) Diphenyl- (45) acetonitrile Diethyl(45) malonate NADÉT (51) Cysteine (51)

Benzophenone Benzophenone Benzophenone Dimer

cationic anionic neutral cationic

29.4 3.5 4.8 34.8

Dimer

cationic

13.9

NAWCystine

cationic cationic

48 36

*In a l l cases n e g l i g i b l e y i e l d s were obtained without any surfactant present. One can observe s i m i l a r e f f e c t s i f the same s u r f a c t a n t s a r e used as e m u l s i f y i n g agents· T a b l e I I I shows r e s u l t s obtained i n benzene - aqueous two molar sodium hydroxide emulsions u s i n g d i f f e r e n t s u r f a c t a n t s . Again i t can be seen that the f i l m forming c a t i o n i c s u r f a c t a n t causes marked i n c r e a s e s i n y i e l d s . Apparently, key e f f e c t i s the f a c t that the hydrophobic e l e c t r o d e f i l m blocks the competing r e a c t i o n of the e l e c t r o d e w i t h water. The hydrophobic l a y e r a l s o f u r n i s h e s an environment which p r o t e c t s a n o d i c a l l y formed f r e e r a d i c a l s . Thus i t i s p o s s i b l e to o b t a i n a p p r e c i a b l e y i e l d s o f dimers o f such compounds as d i p h e n y l a c e t o n i t r i l e (51) and diethylmalonate (51.52) as can be seen i n T a b l e I I . I n the o x i d a t i o n o f s t i l b e n e one can see a d i f f e r e n c e i n product depending on the s i z e o f the molecule

American Chemterf Society Library 1155 16th St. N. W. Washington, D. C. 20089


148


Table I I I The E f f e c t of Surfactants on the Y i e l d s Obtained In E l e c t r o o x i d a t i o n s on Platinum E l e c t r o d e s i n Benzene-2M Aqueous Sodium Hydroxide Emulsions* Compound Benzhydrol(44) Benzhydrol(44) Bénzhydrol(44) D i p h e n y l - (44) acetonitrile Benzyl (44) alcohol cr-methyl benz y l alcohol(44) p-methyl benz y l a l c o h o l (44) p - n i t r o benz y l alcoholC44)

Product

Type of

Surfactant

Yield î

Benzophenone Benzophenone Benzophenone Dimer

Cationic Anionic Neutral Cationic

23.8 2.8 4.0 19.7

Benzaldehyde

Cationic

17.8

Acetophenone

Cationic

21.3

p-tolualdehyde

Cationic

29.9

p-nitrobenzaldehyde

Cationic

23.3

*WLthout s u r f a c t a n t others had 0.0% y i e l d .

the benzhydrol had 0.4% y i e l d and a l l


8.

FRANKLIN E T A L .


149

making the film. With the smaller tetraethylammonium chloride where water can attack the radical one obtains predominantly the ketone, but when Hyamine 2389 i s used the product i s an o i l . It should be pointed out that these are not good synthesis methods. I t i s d i f f i c u l t to separate the product from the sur factant. The yields listed i n Table II are the isolated y i e l d s . Undoubtedly the true yields are higher. Coulometric studies indicate that in several cases the yields approach 100%. Heterogeneous C a t a l y s i s

Micelle catalysis of such reactions as the hydrolysis of ethyl benzoate have been extensively studied (53,54). Although platinum does not normally catalyze the hydrolysis, i f one i n serts a piece of platinum into a solution in which the micelle catalyzed reaction i s occurring the rate i s accelerated (50). The increase in rate i s linearly proportional to the area of the platinum (Figure 5). If one varies the concentration of the surfactant one sees a periodic r i s e and f a l l in the extra cat alysis caused by the platinum. The increase i n catalysis by platinum rises to about 4.0 Χ 10" M/sec at 22 mM Hyamine» de creases to about 0 at 45 mM, increases to 3.8 M/sec at 95 mM. A logical explanation of this data can be obtained from the structure of the film. Figure 6 shows a simplified model of the filmed electrode with multilayers present. As one adds small amounts of surfactant one forms an inverted micelle and obtains the extra catalysis of the inverted micelle causing a rise in the rate. As more surfactant i s added the normal micelle starts to form on the surface and the rate drops back toward the catalysis of the normal micelle. This process i s repeated through the second and third layers (50). That one i s looking at catalysis by an adsorbed film can further be shown by potentiostatting the metal at various potentials (50). At +1.4 volts where the chloride i s more strongly adsorbed the reaction rate is 11.8 X 10~ M/sec. It de creases as the potential decreases reaching a minimum of about 7.8 X 10~ M/sec around the zero point of charge and then begins to increase again reaching 11.8 X 10~ M/sec again around -0.6 V. The increase in the negative potential region is probably due to direct adsorption of the quaternary ion. 6

6

6

e

Iodide Oxidation Because inorganic systems do not generally need the s o l ubillzing a b i l i t y of the surfactants studies of inorganic systems have been limited to such f i e l d s as the role of additives i n electroplating. There i s however an interest i n studying simple inorganic ions to determine what type of substance w i l l penetrate the f i l m . Most of the work i n our laboratory has concentrated on the iodide ion. Iodide gives no oxidation wave in aqueous 2N


150


1.2

Ο 5 AREA,cm

K>

15

20

25

2

Figure 5. The effect of added platinum metal on the hydrolysis of ethyl benzoate in the presence of Hyamine 2389 (4.87 X 10 M). Key: • , rate in the absence of platinum or surfactant, and O, rate in the presence of platinum and surfactant. z


8.

FRANKLIN ET AL.


151

Figure 6. Simplified schematic of multilayerfilmsformed on platinum by quaternary chlorides.


152


sodium hydroxide but when Hyamine i s added to the s o l u t i o n an o x i d a t i o n wave showing two maxima develops. The height of these waves are l i n e a r l y p r o p o r t i o n a l to the c o n c e n t r a t i o n of the i o d i d e (49). The product of the o x i d a t i o n of i o d i d e on the f i l m i s i o d a t e . Table IV shows that the y i e l d of iodate increases when Hyamine i s added to the s o l u t i o n and that current e f f i c i e n c y i n c r e a s e s . The l a t t e r f a c t i s caused by the decrease i n the s i d e r e a c t i o n , the e l e c t r o l y s i s of water. Table IV The E f f e c t of Hyamine on the E l e c t r o o x i d a t i o n of Iodide i n Aqueous 2N Sodium Hydroxide (49) NaOH(aq.)

NaOH(aq.) + Hyamine

% Y i e l d of Iodate

2.6

24.0

%Current Efficiency 0.28 30.4 Changes i n concentration of Hyamine causes the same p e r i o d i c v a r i a t i o n i n the r a t e of o x i d a t i o n of i o d i d e as was observed i n the h y d r o l y s i s of e t h y l benzoate. This again shows the i n f l u e n c e of m u l t i l a y e r s of s u r f a c t a n t on the r a t e of the e l e c t r o d e r e a c t i o n . I t f u r t h e r i n d i c a t e s that o x i d a t i o n of i o d i d e occurs at a d i s t a n c e from the e l e c t r o d e , as long as i t i s i n the f i l m (40). Most other ions do not penetrate the f i l m . For example F i g u r e 7 shows that f e r r o c y a n i d e , without Hyamine present g i v e s a simple o x i d a t i o n wave. With Hyamine present the normal wave disappears i n d i c a t i n g that the f e r r o c y a n i d e cannot penetrate t o the e l e c t r o d e . However, there i s a sharp peak a t the p o t e n t i a l a t which the Hyamine normally begins to o x i d i z e . The r e s i d u a l then decreases to a very low c u r r e n t . This f i l m which i s q u i t e impervious to any of the compounds that are normally o x i d i z e d on the Hyamine f i l m (49) probably c o n s i s t s of a Hyamine-ferrocyanide insulating layer. Acknowl edgment We wish to thank The Robert A. Welch Foundation of Houston f o r t h e i r support i n a l l o f these s t u d i e s .


8.

FRANKLIN ET A L .

153


Figure 7. Current-voltage curve for oxidation of ferrocyanide in 2 Ν NaOH. Key: A, 3.3 X W M Fe(CN) ' ; B, 3.3 X lQr* M Fe(CN) ' + Hyamine (1st run); and C, same as Β (4th run). 4

4

6

4

6


154


Literature Cited 1. Ranney, M. W. "Corrosion Inhibitors. Manufacture and Tech nology," Noyes Data Corporation: Park Ridge, New Jersey, 1976. 2. Ashmore, P. G. "Catalysis and Inhibition of Chemical Reac tions," Butterworths: London. 1963. 3. Brown, H. Plating 1968, 55, 1047-55. 4. Kodina, I. P.; Loshkarev, Μ. Α.; Loshkarev, Y. M. Electrokhimiya 1977, 13, 715-20. 5. Murray, R. W. Accounts of Chem. Research 1980, 13, 135-41. 6. Horner, L. "Onium Compound," in Organic Electrochemistry, ed. Baizer, M. M.; Marcel Dekker: New York, NY, 1973, 429-44. 7. El-Samahy, Α. Α.; Ghoneina, M. M.; Issa, I. M.; Tharwat, M. Electrochim. Acta 1972, 17, 1251-9. 8. Mairanovshii, S. G.; Proskurovskaya, I. V.; Rubinskaya, T.Ya. Elektrokhimiya 1974, 10, 1502-6. 9. Mairanovskii, S. G. Elektrokhimiya 1969, 5, 757-9. 10. Chargelishvili, V. Α.; Dzhaparidze, D. I.; Shavgulidze, V.V. Elektrokhimiya 1974, 10, 1414-17. 11. Gunderson, N.; Jacobsen, E. J. Electroanal. Chem. Interfacial Electrochem. 1969. 20, 13-22. 12. Nyberg, K. J . Chem. Soc. 1969, 13, 774-5. 13. Martigny, P.; Simonet, J. J . Electroanal. Chem. Interfacial Electrochem. 1979, 101, 275-9. 14. Fischer, Hellmuth J. Electroanal. Chem. Interfacial Electro chem. 1975, 62, 163-78. 15. Simonet, J.; Lund, H. J. Electroanal. Chem. Interfacial Electrochem. 1977, 75, 719-30. 16. Piccardi, G. J. Electroanal. Chem. Interfacial Electrochem. 1977, 84, 365-72. 17. Baizer, M. M. J. Electrochem. Soc. 1964, 111, 215. 18. Childs, W. V.; Walter H. C. A I Ch Ε Symp. Ser. 1979, 75, 19-25. 19. Brockmann, C. J.; McKee, R. H. Trans. Electrochem. Soc. 1932, 62,203. 20. Gerapostolou, B. G.; McKee, R. H. Trans. Electrochem. Soc. 1935, 68, 329. 21. Eberson, L.; Helgee, Β. B. Chem. Scri. 1974, 5, 47. 22. Eberson, L.; Helgee, B. Acta Chem. Scand. 1975, B29, 451. 23. Eberson, L.; Helgee, B. Acta Chem. Scand. 1978, B32, 157. 24. Hayano, S.; Shinozuka, N. Bull. Chem. Soc. Japan 1969, 42, 1469. 25. Eberson, L.; Helgee, B. Acta Chem. Scand.1978, B32, 157. 26. Eberson, L.; Helgee, B. Acta Chem. Scand. 1978, B31, 813. 27. Pletcher, D. Tomov, N. J . Appl. Electrochem. 1977, 7, 501. 28. Hayano, S.; Shinozuka, N. Bull. Chem. Soc. Japan 1970, 43, 2083. 29. Hayano, S.; Shinozuka, N. Bull. Chem. Soc. Japan 1971, 44, 1503.


8. FRANKLIN ET AL.


155

30. Day, R. A. Jr.; Underwood, A. L.; Westmoreland, P. G. Anal. Chem. 1972, 44, 737. 31. Erabi, T.; Huira, H.; Tanaka, M. Bull. Chem. Soc. Japan 1975, 48, 1354. 32. Franklin, T. C.; Sidarous, L. Chem. Comm. 1975, 741. 33. Proske, G. E. O. Anal. Chem. 1952, 24, 1834. 34. Hayaon, S.; Shinozuka, N. Bull. Chem. Soc. Japan 1969,42,1469 35. Day, R. A. Jr.; Underwood, A. L.; Westmoreland, P. G. Anal. Chem. 1972, 44, 737. 36. Erabi, T.; Hiura, H.; Tanaka, M. Bull. Chem. Soc. Japan 1975, 48, 1354. 37. Leh, Peter; Kuwana, T. J. Electrochm Soc. 1976, 123, 1334-9. 38. Smith, J. D. B.; Phillips, D. C.; Davies, D. H. J. Polym. Sci., Polym. Chem. Ed. 1977, 15, 1555-62. 39. Noel, M.; Anantharaman; Udupa, H. V. K. Electrochim. Acta 1980, 25, 1083. 40. Gerischer, H. Z. Elektrochem. 1960, 54, 366. 41. de Levie, R. J. Electrochem. Soc. 1971, 118, 185c. 42. Abubacker, K. M.; Malik, W. U. J. Indian Chem. Soc. 1959, 36, 463. 43. Franklin, T. C.; Sidarous, L. Chem. Comm. 1975, 741. 44. Franklin, T. C.; Sidarous, L. J. Electrochem. Soc. 1976. 124, 65-69. 45. Franklin, T. C.; Honda, T. Micellization, Solubilization, and Microemulsions, edited by Mittal, 1977, 2, 617-626. 46. Franklin, T. C.; Honda, T. Electrochimica Acta 1978, 23, 439-444. 47. Franklin, T. C.; Iwunze, M. J of Electroanalytical Chemistry, 1980, 108, 97-106. 48. Franklin, T. C.; Iwunze, M. Analytical Chemistry 1980, 52, 973-976. 49. Franklin, T. C.; Gibson, S. Article in preparation. 50. Franklin, T. C.; Iwunze, M. Article submitted. 51. Franklin, T. C.; Iwunze, M. Paper presented at Spring, 1980 Electrochemical Society Meeting in St. Louis. 52. Liang, C.; Franklin, T. C. Electrochim. Acta 1964, 9, 517. 53. Bunton, C. A. Pure and Applied Chem. 1977, 49, 969. 54. Fendler, J. H. Accts. Chem. Res. 1976, 9, 153.

RECEIVED

August 12, 1981.

The Use of Cationic Surfactants in Electrochemistry and Catalysis on

Recommend Documents