A C T A U N I V E R S I T A T I S L O D Z I E N S I S F OL IA C H I M I C A 10, 1993 W o j c i e c h J. K i n ar t* 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 V A R I O U S O R G A N I C n - E L E C I R O N S Y S T E M S The c o m p a r a t i v e s t u di es of the s e r i es of o r g an ic TT-electron s y s t e m have been c a r r i e d out u s i n g the cyc li c vo l ta m m e t r y . The aim of this work was to g e n e r a t e free r a d i c a l s from some o r g a n i c c o m p o u n d s under study, and then to d e t ec t them wi th u si ng the c y c l o - v o l t a m m e t r i c methods. T h e r e fore the f o l l o w i n g c o m p o u n d s have been o xi d ize d: ant h ra c en e, tri p ty c en e, p-terphenyl, 1, 8 - d i h y d r o x y - 9 - a n t h r o n e , 9-anthrone, a z o b e nz e ne , 4 , 4 ’- d i m e t h y l a z o b e n z e n e , 4 , 4 ’- d i - t e r t - b u t y l a z o - be n zene , 2 , 5 - d i m e t h y 1 - 1 , 3 , 4 - t h i a d i a z o l e , 2 , 5 - d i - t e r t - b u t y 1- -1, 3 , 4 - t h i a d i a z o l e , and N , N ,N ’ ,N ’- te t ra m et hy 1 - p - ph e n y l e n e d i a - mine. I have been e n c o u r a g e d to carry out this work, since only a few o c c a s i o n a l wor ks u s i n g ESR have so far been p e r f o r m e d for some of these c o m p o u n d s [l, 2] . This novel ESR s tu dy has con fi rmed that a nt h r a c e n e , tri p ty c en e, p - t e r p h e n y l and a z o b e n zene are apt to form free r ad i c a l s in their s o l u t i o n s in di- c h l o r o m e t h a n e . A dd i t i o n a l l y , only the v o l t a m m e t r i c r es ults c o u l d e n a b le to a r r a n g e the s t u d i e d c o m p o u n d s in some order fai rly p a r a l l e l to their o x i d a t i o n p ot e n t i a l s , w hi ch ref lect their a b i l i t y to be o x i d i z e d to free rad ical s.
S ev e ra l v al ues of the o x i d a t i o n p o t e n t i a l s for a n t h r a c e n e in v a r i o u s s ol v e n t s h av e been rep orted. For e xa mple , S w a n h o l m
[3] has found that its o x i d a t i o n p o t e n t i a l ( E q x ) is equal to 1.31 V (vs SCE) in C H 2 C 1 2> w h e r e a s H a m m e r i c h [4] has r e p o r t e d v al ue of Eq x = 1.40 V (vs SCE) in C H 2 C 1 2 .
Only an o c c a s i o n a l work has been done on the e l e c t r o o x i d a t i o n of azo c o m p ou n ds . F l o r e n c e [5] has r e p o r t e d that a z o b e n z e n e d i s s o l v e d in 5% aq. m e t h a n o l is not o x i d i z e d over the p o t e n t i a l range of the p y r o l y t i c g r a p h i t e e l e c t r o d e (1.2 V vs SCE), and the s tr o n g l y
e l e c t r o n - r e l e a s i n g groups, such as N C C H ^ ^ and DH, m us t be p r e s e n t to o b t a in in such s ys tem an o x i d a t i o n w av e as well as that such c o m p o u n d s u nd e r g o a 2 - e l e c t r o n ox i da ti o n. This result is in a g r e e m e n t wi th o th er w or ks [6]. There are no a v a i l a b l e l i t er a tu r e data abo ut o x i d a t i o n of t er p hen yl. P a r k e r et al. [7] have c o m p a r e d the p r o p e r t i e s of sev eral p ,p ’- d i m e t h o x y p o l y - phe nyls , with i n c l u di n g p , p ’- d i m e t h o x y t e r p h e n y l , u s i n g the vol- t a m m e t r i c method. He found the first c h a r ge t ra nsfe r for those c o m p o u n d s to be a q u a s i - r e v e r s i b l e o n e - e l e c t r o n with the peak s e p a r a t i o n b ei ng s l i g h t l y g r e at er than 60 m V. Also the sec on d o x i d a t i o n step, from a c a t io n rad ical to a d ic a tio n, was reversible for all the co m po un d s. P a r k er found the f o l l o w i n g o x i d a t i o n p o t e n t i a l s for p ,p ’- d i m e t h o x y t e r p h e n y l m e a s u r e d in the m i x t u r e c o m p o s e d of C I ^ C ^ - TFAn - T F A (4 5 : 5 : 1) Ep, an^ = 1,65 V (vs SCE). H a n d et al. [8] have e x p l a i n e d the m a r k e d s t a b i l i t y of c a t io n r ad i c a l s for med from N ,N ,N ’ ,N t e t r a m e t h y l - p - p h e n y l e n e - di a m i n e in a c e t o n i t r y l e as the res ult of the s t r o n g d e l o c a l i z i n g po wer of the s e c on d d i m e t h y l a m i n o group. Z w e i g [9] has r e p o r t e d the p o l a r o g r a p h i c h a l f - w a v e o x i d a t i o n p o t e n t i a l of the a f o r e m e n t i o n e d p - p h e n y l e n e d i a m i n e in a ce t o n i t r y l e , at a r ot a t i n g p l a t i n u m el e ct ro d e, to be equal to
E 1/2 = - 0.10 V vs Ag/ 0.01 M A g +
A l t h o u g h it is well r e c o g n i z e d that the p h a r m a c o l o g i c a l a c t i v i t y of m os t n at ural or s y n t h e t i c a n t h r a q u i n o n e s i nv o l v e s the c o r r e s p o n d i n g ant h ro n es , their way of a c t i on is not yet u n d e r st o od . A mo ng these co m po un d s, a n t h r a l i n ( 1 , 8 - d i h y d r o x y - 9 - -an t hr o ne ) is of p a r t i c u l a r i nt eres t [10], as it is one of the chief d ru gs in the u p - t o - d a t e t r e a t m e n t of p s o r i a s i s and r e l at ed skin des eases.
E X P E R I M E N T A L
The cell used for the v o l t a m m e t r y was a two-compartment vessel wi th w o r k i n g and c o u n t e r e l e c t r o d e s in one cha mber , and s e p a r a t ed from c h a m b e r of the r e f e r e n c e e l e c t r o d e by a s i n t e r e d glass.
P l a t i n i u m g au ze e l e c t r o d e was used as the w o r k i n g e l e c t r o d e in all m e a s u r e m e n t s . A g / A g f s a t u r a t e d e l e c t r o d e was used as the r e f e r e n c e e l e c t r o d e in the C H 2 C 1 2 - TFA - TFAn (23 : 1 : 1) mix ture and 0.1 M B u ^ N B F ^ as a s u p p o r t i n g e l e c t r o l y t e . This m i x t u r e was c h o se n as the best one to m a i n t a i n o p t i m u m c o n d i t i o s for r e c o r d i n g the w e l l - r e s o l v e d v o l t a m m o g r a m s . The s y m b o l s u se d above i nd i cat e, r e s p e c t i ve ly :
TFA - t r i f l u o r o a c e t a t i c acid, TFAn - t r i f l u o r o a c e t a t i c a nh y dri de.
Only for N ,N ,N ’ ,N ’- t e t r a m e t h y 1 - p - p h e n y l e n e d i a m i n e , azobenzene and 9 - a n t h r o n e the v o l t a m m o g r a m s were r e c o r d e d in a c e t o n i t r y l e . A g/ 0. 1 M A g + was used here as the r e f e r e n c e electrode, and 0.1 M L i C l O^ as a s u p p o r t i n g e le c t r o l y t e . All the m e a s u r e m e n t s were c a r r i e d out u si ng a P G- 30-1 A p o t e n t i o s t a t (with IRe c o m p e n s a tion) with a l in ear sweep g e n e r a t o r [ l l ] . Also all v o l t a m m o g r a m s of the s tu d i e d c o m p o u n d s were r ec o r d e d with the a v o l t a g e sweep r ate equal to 100, 200, 300, 400, 500 and 600 mV s ^ at 298 + 0.2 K.
D i c h l o r o m e t h a n e was s t o re d over P 2 0 5 for few hours, and, then it was r e d i s t i l l e d twice, 4 , 4 ’- d i - t e r t - b u t y l a z o b e n z e n e , 4,4' - d i - m e t h y l a z o b e n z e n e , 2 , 5 - d i m e t h y l - l ,3,4 - t h i a d i a z o l e and 2 , 5 -d i- - t e r t - b u t y l - 1 ,3,4 - t h i a d i a z o l e were s y n t h e s i z e d by the k no wn m e t h o d s [l2J . Other c o m p o u n d s lis ted b el ow were c o m m e r c i a l l y a v a i l ab l e, and they were used w i t h o u t any f u r th er p u r i f i cation.
R E S UL TS AND D I S C U S S I O N
The f o l l o w i n g v a l u es of the ano di c h a l f - p e a k p o t e n t i a l s (Ep, a/2) have been foud for the s t u di ed p i - e l e c t r o n s y s t e m s in the m i x t u r e m ad e of C H 2 C 1 2 - TFA - TFAn (23 : 1 : 1) on the p l a t i n u m e l e c t r o d e (sw eep rate, 200 mV/s); A g/ Ag was used as a r e f e r e n c e e l e c t r o d e .
T a b l e 1 Ep, a/2 a n t h r a c e n e 0.67 t r i p t y c e n e 1.35 p - t e r p h e n y 1 1.10 az o b e n z e n e 1.28 4 , 4 ’- d i m e t h y l a z o b e n z e n e 1.40 4 , 4 ’- d i - t e r t - b u t y l a z o b e n z e n e 1.41 l , 8 - d i h y d r o x y - 9 - a n t h r o n e • 1.33 2 , 5 - d i - t e r t - b u t y l - l , 3 , 4 - t h i a d i a z o l e 1.65 2,5 -d ii n et hy l -l ,3 , 4- t hi ad i az ol e 1.69 c = 1.0 m M .
The f o l l o w i n g v a l ue s of the ano di c h a l f - p e a k p o t e n t i a l s (Ep, a/2) have been found in a c e t o n i t r y l e for the s t u d i e d c o m p o u n d s vs Ag/ 0.1 M A g + . S we ep rate 200 mV/s. T a b 1 e 2 Ep, a/2 N , N , N ’ , N ’- t e t r a m e t h y l - p - p h e n y l e n e d i a m i n e -0 28 9 -a n t h r o n e 1 91 a z o b e n z e n e 1 38 c = 1.0 m M .
Only for a n t h r a c e n e in the - TFA - TFAn (23 : 1 : 1) m i x t u r e c o n t a i n i n g B u ^ N B F ^ i O . l M), and for N , N , N ’ , N ’-tetramethy 1- - p - p h e n y l e n e d i a m i n e in C H j C N c o n t a i n i n g L i C l O ^ C O . l M), the r e v er s i b l e o n e - e l e c t r o n o x i d a t i o n peak were obs erve d. V o l t a mm o - g ra ms for all o th er c o m p o u n d s do e x i b i t the i r r e v e r s i b l e or, as for a z o b e nz e ne , the q u a s i - r e v e r s i b l e o x i d a t i o n peaks. On the
r e v e r s e scan, m e r e l y for a n t h r ac e ne , N ,N ,N ’ ,N ’-tetramethy1-p-phe- n y l e n e d i a m i n e , p - t e r p h e n y l and the a zo b e n z e n e , the r e d u c tion p ea ks w er e o bs e rve d. The re was no t e m p e r a t u r e e f f e ct on a s h ape of the v o l t a m m o g r a m s under s tu dy as well ( dr a s t i c d e c r e a s e in t e m p e r a t u r e had not i mp r o v e d their shape). Full e x p l a n a t i o n of these e f f e c t s r e q u i r e s f u r th er studies. The a n o di c o x i d a t i o n of a n t h r a c e n e has e x t e n s i v e l y been s t u d i e d by o th er a u t h o r s [13-15], and it has been used as a model c o m p o u n d in o rd er to e s t a b l i s h the o n e - e l e c t r o n o x i d a t i o n p a t h w a y of a r o m a t i c h y d r o c a r b o n s in a p r ot ic media.
S im i la r ly , in our work we h av e used a n t h r a c e n e as the model c o m poun d. The v al ue of the a n o d ic peak p o t e n t i a l m e a s u r e d by us in the C H - C ^ : TFA : TFAn (23 : 1 : 1) m i x t u r e in r e f e r e n c e to the sil ve r c h l o r i d e e l e c t r o d e is e qu al Ep, a/2 = 1.15 V. This p o t e n t i a l is c lo se to val ue s r e p o r t e d by S w a n h 0 1 m [2]. The value of the a no dic h a l f - p e a k p o t e n t i a l Ep, a/2 = 0.67 V l is te d in Tab. 1 was m e a s u r e d in r e f e r e n c e to the silver e l e c t r o d e ( A g / A g + sa t ur at e d) . Ep, a/2 is much lower for anthracene than for t r i p t y c e n e and p -t e r p h e n y l . It i n d i c a t e s that it is much e a s i er to from a free c a t io n rad ic al from a n t h r a c e n e than from o th er two h y d r o c a r b o n s .
S i m i l a r l y as P a r k e r [17] for p ,p ’- d i m e t h o x y t e r p h e n y 1 I have o b s e r v e d also the t wo - st e p o x i d a t i o n of t e r p h e n y l the s ha pe of w av es c o r r e s p o n d i n g to these two steps d i f f er c o n s i d e r a b l y for each of them. Only for the first of them the c at ion r e d u c t i o n peak was o bs erve d. But the q u o t i e n t of the c a t h o d i c and the ano di c peak c u r r e n t s was lower than u ni ty ( ic / i g ). It i n d i c a t e s that the e l e c t r o c h e m i c a l o x i d a t i o n is f o l l o w e d he re Dy a c he m i c a l r ea ctio n. The h a l f - p e a k p o t e n t i a l fou nd for t ri p tyc ene e q u al s to 1.35 V (vs A g / A g + sat u ra t ed ).
It was q ui te i n t e r e s t i n g to c o m p a r e the a b i li ty to be o x i d iz ed to the c a t i o n r a d i c a l s of d i s c u s s e d a bo ve three h y d r o c a r bons with 9 - a n t h r o n e and 1, 8 - d i h y d r o x y - 9 - a n t h r o n e . The fact that a n t h r a l i n and a n t h r o n e are able to from free r ad i c a l s was c o n f ir me d by e a r l i e r s t u d i e s [10].
I have f ou nd for 1, B - d i h y d r o x y - 9 - a n t h r o n e Ep, a/2 = 1.33 V (vs A g / A g + s at u r a t e d ) . The h a l f - p e a k p o t e n t i a l for a n t h r o n e was so h ig h (it was c l o s e to the d e c o m p o s i t i o n p o t e n t i a l of the m ix ed
azobenzene 4,4'-di-methylazobenzene 4,4’-di-tert-butylazobenzene
Vvs A g/ Ag+ V v s A g / A g + V v s A g / A g +
Fig . 1
s o l v e n t C H 2 C 1 2 : TFA : TFAn) that it was n e c e s s a r y to r ep eat the m e a s u r e m e n t s in a c e t o n i t r i l e c o n t a i n i n g L i C l O ^ i O . l M). Ep, a/2 was found to be equal to 1.91 V (vs Ag/ 0.1 M A g + ). New r es ults w o u l d in d ic at e that i n t e r a c t i o n b et w e e n the C-H bond in p os i t i o n 10 for 1 , O - d i h y d r o x y - 9 - a n t h r o n e is much w e a ke r than for 9-anthrone. It is also k n o w n that the i nc r e a s e in the a c t i v i t y aga in st p s o r i a s i s for d i f f e r e n t a n t h r o n s is a rr a n g e d a c c o r d i n g the follow ing order: 9 - a n t hr o ne , l - h y d r o x y - 9 - a n t h r o n e , 1 , 8 - d i h y d r o x y - 9 - -a n th ro n e. We have also o b s e r v e d considerable d i f f e r e n c e s b e t we en a z o b e n z e n e and its 4 , 4 ’- d i s u b s t i t u t e d d e r i v e r a t i v e s . Only for a z o b e n z e n e in the C H 2 C 1 2 : TFA : TFAn m i x t u r e the o n e - e l e c t r o n q u a s i - r e v e r s i b l e o x i d a t i o n p ea ks were o bs e rve d, whereas for other two c o m p o u n d s u nd er s tu dy the o x i d a t i o n p ea ks were i r r e v e r s i b l e ( see Fig. 1).
Also their o x i d a t i o n p o t e n t i a l s dif fe r c on s i d e r a b l y . Ep, a/2 = 1.28 V (vs A g / A g + s a t u r a t e d ) for azo b en z en e. The o x i d a t i o n h a l f - p e a k p o t e n t i a l s for 4 , 4 ’- d i m e t h y l a z o b e n z e n e and for 4 , 4 ’-di- - t e r t - b u t y l a z o b e n z e n e are equal to 1.40 V and 1.41 V (vs A g / A g +
s at u r a t e d ) , r es p e c t i v e l y . The d i f f e r e n c e b e t w e e n a z o b e n z e n e and its d e r i v a t i v e s can be e x p l a i n e d as the r e s u lt of g r e a t e r s t a b i lity of the a z o b e n z e n e c a t i o n r ad ical than those o b t a i n e d from two oth er c o m p o un d s. Si m il ar l y, the ESR m e a s u r e m e n t s c a r r i e d out in the a n a l o g o u s to my m i x t u r e [2], in c o n j u c t i o n wi th the e l e c t r o lysi s, p r o ve d that it was m uc h e a s ie r to o b t ai n w e l l - r e s o l v e d s p e c t r u m for a z o b e n z e n e than for its 4 , 4 ’- d i s u b s t i t u t e d d e r i v a t i ves. The ano di c h a l f - p e a k p o t e n t i a l was also fo und for a z o b e n z e n e (Ep, a/2 = 1.38 V (vs Ag/ 0. 1 M)). A z o b e n z e n e was used he re as the r e f e r e n c e s u b s t a n c e to e n a bl e c o m p a r i s o n of the o x i d a t i o n p o t e n t i a l s in C H 2C 1 2 lis ted in Tab. 1 wi th those found in CH-jCN and c o l l e c t e d in Tab. 2. N ,N ,N ’ ,N ’- T e t r a m e t h y 1 - p - p h e n y l e n e d i a m i - ne has been used by other a u t h o r s as the m o d e l s y s t e m for b i o l o gical s t u d i e s r e q u i r i n g a r e v e rs i bl e, o n e - e l e c t r o n redox system, m ost n o t a b l y in the p i o n e e r i n g work of M i c h a e l i s [l 6]. Ep, a/2 m e a s u r e d by me for this c o m p o u n d in a c e t o n i t r y l e equ al s to -0.28 V vs Ag/ 0. 1 M A g + . This value is s l i g h t l y lower than that r e p o r t e d by . Z w e i g [9] who used a r o t a t i n g p l a t i n u m e l e c t ro de .
How ever , also my v o l t a m m o g r a m s c o n f i r m e d a m a r k e d s t a b i l i t y of the g e n e r a t e d c a t i o n r ad ical and the d i c a t i o n o b t a i n e d from this o xi d ati on. F in ally , I was c o n c e r n e d to c o m p a r e the o x i d a t i o n p o t e n t i a l s for all the a f o r e m e n t i o n e d c o m p o u n d s w it h tho se of 2 , 5 - d i m e t h y l - l ,3,4 - t h i a d i a z o l e and 2 , 5 - d i - t e r t b u t y l - l ,3,4 - t h i a diazole. The v al ue of the ano di c h a l f - p e a k p o t e n t i a l for the f or mer one is s l i g h t l y h i g he r than that for the latter. It m ea ns that alkyl g r o up s s u b s t i t u t e d in p o s i t i o n s 2 and 5 i n f l u e n c e in a very l i m it ed way the o x i d a t i o n pot enti als for the two t h i a d i a z o l e s . P re s u m a b l y , an e l e c t r o n hole in r a d i c a l s of t he se c o m p o u n d s is l o c a l i s e d on the s u l f u r atom, this c o n c l u s i o n s e e m s to be sup- p or ed by the work of F a b r e t t i [ 17], who s t u d i e d 2 , 5 - d i m e t h y l - l , 3 , 4 - t h i a d i a z o l e . He p r o ve d the c o o r d i n a t i o n of this azo le t h r ou gh the s u l fu r atom.
L i s t e d in Tab. 1 and 2 the h a l f - p e a k o x i d a t i o n p o t e n t i a l s r ef l ec t the a b i l i t y of the s t u d i e d c o m p o u n d s to f r o m free ra d i c al s a ft er the ox i da ti o n. Ep, a/2 v a l ue s i n c r e a s e a c c o r d i n g to the f o l l o w i n g order: N ,N ,N ’ ,N ’- t e t r a m e t h y 1 - p - p h e n y l e n e d i a m i n e a n t h r a c e n e , p - t e r p h e n y l , a z o b e n z e n e , l , 8 - d i h y d r o x y - 9 - a n t h r o n e ,
trip-tycene, 4 , 4 ’- d i m e t h y l a z o b e n z e n e , 4 , 4 ’- d i - t e r t - b u t y l a z o b e n z e n e , 2 , 5 - d i - t e r t - b u t y l - l , 3 , 4 - t h i â d i a z o l e , 2 , 5 - d i m e t h y l - l , 3 , 4 - t h i a d i a - zole, and 9 -a n thr one.
R E F E R E N C E S
[1] 3. L . C o u r t n e i d g e , A . G . 0 a v i e s , D . C . M e G a u c h a n, Rec. Trav. Chim., 1 0 7 , 190 -196 (1988).
[2] D.C. M c G a u c h a n , P r i va te c o m m u n i c a t e , Dept. Chem., Univ. College, London.
[3] U . S v a n h o 1 m , V . D . P a r k e r , J . Chem. Soc., P e r kin T r a n s . , 2 , 1567 (1976).
[4] 0. H a m m e r i c h, V. D. P a r k e r, J. Am. Chem. Soc., 96, 4289 (1974).
[5] T. M. F 1 0 r e n c e, F. J. M i 1 1 e r, H. E. Z i t t e 1, Anal. Chem., ¿8, 1065 (1966).
[6] L. L a d a n y i , M. V a 3 d a, A. M a g i , G. V a n e s , Acta Chim. Acad. Sei. Hung., 245 (1970).
[7] A. R o n l a n , 0. C o l l e m a n , 0. H a m m e r i c h , V . D . P a r k e r , J . Am. Chem. Soc., 96, 845 ( 1974).
[8] R . H a n d , M . M e 1 i c z a r e k , D . I . S c 0 g g i n , R . S t o t z , A. K. C a r p e n t e r , R. F. N e l s o n , C o l l e c t io n C ze c h o s l o v . Chem. Commun. 3_6, 842 (1971).
[9] A. Z w e i g , 3. E. L a n c a s t e r , M. T. N e g l i a , W. H. 3 u r a, 3. Am. Chem. Soc., 86, 4130 (1964).
[10] M. d ’I s c h i a , A. P r i v i t e r a , G. P r o t a , Tetra hed ro n Lett., 25, 4037 (1984). [11] B. 3 a k u s z e w s k i , M . C z a j k o w s k i , T. B l a - s z c z y k, P o l is h Pat. 100959, 1977, 786. [12] 0. N . W i t t , D . U e r m e n y i , B er l i n e r Ber., 4_6, 296 (1913). P. B. R a s m u s s e n , U. P e d e r s e n , I . T h o m s e n , B. Y d e, Bull. Soc. Chim. France, £2, (1) (1985).
[13] H. L u n d, Acta Chem. Sc a nd ., I I, 1323 (1957).
[14] K . E . F r i e n d , W . E . 0 h n e s 0 r g e , 3. Org. Chem., 28, 2435 (1963).
[15] E. J. M a j e s k i, J. D. S t e w a r t, W. E. 0 h n e- s o r g e, 3. Amer. Chem. Soc., £0, 633 (1968).
[16] L. M i c h a e l i s . M . P. S c h u b e r t , S. G r a n i c k , J. Am. Chem. Soc., 61, 1981 (1939).
[17] A. C. F a b r e t t i , G. C. F r a n c h i n i , G. P e y r o - n e 1, S pe c tr o c h i m . Acta, _36 A, 609 (1980). W o j c i e c h 3. K i n a rt E L E K T R O C H E M I C Z N E U T L E N I A N I E R Ó Ż NY CH O R G A N I C Z N Y C H TT - E L E K T R O N O W Y C H U K Ł AD ÓW P r z e p r o w a d z o n o b a d an ia e l e k t r o c h e m i c z n e g o u t l e n i a n i a s ze regu z w i ą z k ó w organicznych- za pom oc ą w o l t a m p e r o m e t r i i c yk l i c z n e j . Na p o d s t a w i e o t r z y m a n y c h w ar t oś c i p o t e n c j a ł ó w u t l e n i a n i a w CH-jCN i i C H 2C l 2 o c e n i o n o z do l n o ś ć tych z w i ą z k ó w do t w o r z e n i a wolnych rod n i k ów w w y n i ku b a d a n e g o procesu.
