This article was downloaded by: [University of Illinois at Urbana-Champaign]On: 06 October 2014, At: 10:23Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

Analytical LettersPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/lanl20

The Use of µ-Oxo-ditrifluoroacetato-diphenyl-diiodinein Potentiometric TitrationsI. N. Papadoyannis a & J. K. Gallos aa Laboratories of Analytical Chemistry and Organic Chemistry , Aristotelian University ofThessaloniki , 54006, Thessaloniki, GreecePublished online: 15 Dec 2006.

To cite this article: I. N. Papadoyannis & J. K. Gallos (1985) The Use of µ-Oxo-ditrifluoroacetato-diphenyl-diiodine inPotentiometric Titrations, Analytical Letters, 18:6, 763-771

To link to this article: http://dx.doi.org/10.1080/00032718508066174

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon andshould be independently verified with primary sources of information. Taylor and Francis shall not be liable forany losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoeveror howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use ofthe Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

ANALYTICAL LETTERS, 18(A6), 763-771 (1985)

THE USE OF p-0x0-DITRIFLUOROACETATO-DIPHENYL-DIIODINE IN POTENTIO-

METRIC TITRATIONS

KEY WORDS: v-0x0-ditrifluoroacetato-diphenyl-diiodine, oxidimetric

titrant, aqueous-acetonitrile media, simultaneous, hydrazine, ni-

trites, selenocyanates, and thiocyanates.

I.N. Papadoyannis and J.K. Gallos

Laboratories of Analytical Chemistry and Organic Chemistry, Aristo-

telian University of Thessaloniki,54006 Thessaloniki, Greece.

ABSTRACT

The use of p-0x0-ditrifluoroacetato-diphenyl-diiodine (p-ODDD)

in potentiometric titrations has been studied.This reagent is more

powerful oxidizing agent and more stable than bis(trif1uoroacetoxy)

iodobenzene (BTIB). The general analytical conditions for using this

oxidant and the procedures for potentiometric determinations of sul-

fite, thiosulphate, nitrite, selenocyanate, thiocyanate and iron(I1)

ions as well as hydrogen peroxide and hydrazine sulphate are descritr

ed . A simultaneous determination of hydrazine sulphate and nitrite

ions and also of selenocyanate and thiocyanate ions has been carried

out.

7 6 3

Copyright 0 1985 by Marcel Dekker, Inc. 0003-27 19/8S/1806~763$3.50/0

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

764 PAPADOYANNIS ANJJ GALLOS

INTRODUCTION

In the course of our investigations on new organic titrants

for use in aqueous acetonitrile, it was found that u-oxo-ditrifluo-

roacetato-diphenyl-diiodine (p-ODDD) is ideally suited for this pur-

pose. The solutions of u-ODDD in acetonitrile were found to be more

stable than those of the bis (trif luoroaceroxy) iodobenzene

studied earlier.

(BTIB)’-*

A number of papers have been published on the oxidation and

determination of the above ions. Belcher and co-workers ’ determi- ned thiocyanate and thiosulphate ions by oxidation with iodine in

alkaline solutions to sulphate ions. Jacob and Nair determined

ascorbic acid, iodine, iron(I1) and arsenic(II1) using as oxidime-

tric titrant dichloramine-T in non aqueous and partially aqueous

media, The potential break is about 50mV for the determination of

arsenic(II1). Pillai and Nair used iodosobenzene diacetate, in

non-aqueous or partially aqueous media, for the potentiometric ti-

trations of some reductants.

4

5

In the present paper we report on the potentiometric titra-

tions of sulfite, thiosulpha-te, nitrite, selenocyanate, thiocya-

nate and iron(I1) ions, as well as hydrogen peroxide and hydrazine

sulphate with u-ODDD.

A simultaneous determination of hydrazine sulphate and nitri-

te ions and also of selenocyanate and thiocyanate ions is also de-

scribed.

EXPERIMENTAL

Reagents

u-0x0-ditrif l ,uoroacetato-diphenyl-diiodine (U-ODDD) was pre- 6-7

pared as previously described -

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

POTENTIOMETRIC TITRATIONS 765

Standard solutions of p-ODDD were prepared by dissolving the

appropriate amount of U-ODDD in acetonitrile containing 1% tri-

fluoroacetic acid. This solution was standardized by adding an

excess of potassium iodide solution 5% and titrating the libera-

ted iodine with standard solution of sodium thiosulphate - l

Standard solutions of sulfites, thiosulphates, nitrites, sele-

nocyanates, thiocyanates, iron(I1) ions, hydrogen peroxide and

hydrazine were prepared by dissolving appropriate amounts of them

in distilled water.

Apparatus

A Metrohm Herisau (Multi-Dosimat E415) microburette combined

with a Radiometer Copenhagen TTA60 titration assembly and a Radio-

meter Copenhagen RHM 6 2 Standard pH meter were used.

A clean platinum electrode was used as an indicator electrode

and a standard calomel electrode was used as reference.

General procedure for potentiometric determinations

The titrant was in an acetonitrile solution and the titrand

solutions were in all cases in an aqueous solution. Measured ali-

quots of the titrand solutions were taken in the titration cell

of the TTA 6 0 titration assembly and were diluted with distilled

water to 25 ml. The solutions were automatically stirred and the

solution of LI-ODDD was added from the microburette. Stirring was

stopped before potential readings were taken. All titrations were

gerformed at room temperature.

Procedure f o r potentiornetric titrations of reductant agents

To 3-8 ml of the sulfite (ST) solution,5,0-10-3M,22-17 ml of

distilled water was added and the solution was titrated with Ir-ODDD.

The potential break at end point is 5 5 0 mV (from 3 1 4 mVto 864mV).

To 5-10 r n l of the thiosulphates (S20;) solution,5,0-10~3M , 20-Ism1 of distilled water was added and the solution was ti-

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

766 PAPADOYANNIS AND GALLOS

trated with the titrant. The potential break at end point is

380 mV (from 442 mV to 822 mV) . To 3-10 ml of the nitrites (NO;) ~olution,8,0-10-~M,22-15 ml

of distilled water was added and the solution was titrated with

u-ODDD. Potential break at end point is 210mV (from 535mV tO

745 mv) . To 1-3 ml of the selenocyanates (SeCN-) solution, 6,09- 1 0-3M,

24-22ml of distilled water was added and the solution was ti-

trated with p-ODOD. Potential break at end point is 480mV (from

360 mV to 840 mV) . To 5-20 ml of the thiocyanates (SCN-) solution,I ,006'10-314,

20-5ml of distilled water was added and the solution was ti-

trated with the titrant. Potential break at end point is 350 mV

(from 475 mV to 825 mV) . To 2-8 ml of the iron(I1) ions ~olution,5,0-1O-~M, 23-17 ml

of distilled water was added and the solution was titrated with

w-ODDD. Potential break at end point is 340 mV (from 460mV to

800 mV) . To 1-3 ml of the hydrogen peroxide solutionr3,92-10-3M~24-22

led water was added and the solution was titrated

Potential break at end point is 405mV (from 404mV

ml of disti

with p-ODDD

to 809 mV) . To 1-3 ml of the hydrazine sulphate solution(H2NNH2.H2S04)

,7,0-10-3Mt24-22 ml of distilled water was added and the solution

was titrated with p-ODDD. Potential break at end point is 740mV

(from 199 mV to 939 mV) .

Procedure fo r simultaneous potentiometric titration of selenocyanate

and thiocyanate ions.

To 4 ml of the solution ( 2 ml of 6,09*10-3M SeCW and 2 ml of

1 ,006.10-3M SCN-) 21 ml of distilled water was added and the solu-

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

7 6 7 POTENTIOMETRIC TITRATIONS

tion was titrated with U-ODDD. Selenocyanates were first oxidized

to elemental selenium with a potential jump about 150mV, from 295

mV to 445 mV. The second potential break corresponding to the oxi-

dation of thiocyanate ions to sulphate was about 545 mV from450mV

to 995 mV.

Procedure for simultaneous potentiometric titration of nitrites and

hydrazine.

To 4 ml of the solution ( 2 ml of 8,0.10-3N NO? and 2 ml

7f0.10-3M H2NNH2) 21 ml of distilled water was added and the solu-

tion was titrated with U-ODDD. Hydrazine was first oxidized to ni-

trogen with a potential jump about 320 mV, from 330 mV to 650 mV.

The second potential jump corresponding to the oxidation of nitri-

te ions to nitrate ions is about 306 mV from 695 mV to 1001 mV.

of

RESULTS AND DISCUSSION

Typical results obtained for the potentiometric titrations of

various reductants are presented in Table 1. The end-points were

read from the potentiometric curves . The prososed method was applied to the simultaneous determi-

nation of selenocyanates and thiocyanates. Results from this deter-

mination can be seen in the Table 2 .

Finally we applied this method to the simultaneous determina-

tion of hydrazine and nitrite ions. Results obtained from this de-

termination are presented in Table 3.

It is of interest to note the stability of u-ODDD solution in

acetonitrile in the presence of trifluoroacetic acid. Experimental

results of the stability of BTIB and U-ODDD in acetonitrile solutions

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

768 PAPADOYANNIS AND GALLOS

TABLE 1 P o t e n t i o m e t r i c D e t e r m i n a t i o n of Reductan t Compounds w i t h V-ODDD.

R e d u c t a n t

Compound

H2°2

KSeCN

KSCN

N H 4 ) 2Fe (SO4) - 6 H 2 0

3 Na2S0

Na2S203

K N 0 2

unol of t h e

r e d u c t a n t

:ompound

nmol of -0DDD

Added

(umol)

2 . 9 2

5 . 8 4

8 . 7 6

7 . 0 0

1 4 . 0 0

21 . o o 6 . 0 9

1 2 . 1 3

1 8 . 2 7

5 . 0 3

1 0 . 0 6

2 0 . 1 2

1 0 . 0 0

2 5 . 0 0

4 0 . 0 0

1 5 . 0 0

2 5 . 0 0

4 0 . 0 0

5 . 0 0

7 . 5 0 1 0 . 0 0

2 4 . 0 0

4 8 . 0 0

80 .00

3 . 0 4 t 4 . 0 9 * 1 0 - 2

8 . 8 1 t 5 . 1 7 . 1 0-2

8 . 8 2 2 5 . 3 3 -1 0-2

7 . 0 6 t 3 . 8 1 ’ 1 0-2

1 3 . 9 7 2 4 . 9 4 . 1 0-2

2 0 . 7 7 t 6 . 8 4 * 1 0-2

11 . 8 3 i 4 . 1 9 - 1 0 - 2

1 7 . 9 7 A 6 . 2 4 . 1 O-’

5 . 0 7 2 3 - 0 6 . 1 0-2

1 0 . 7 1 t 4 . 9 7 - 1 O-’ 21 . 3 3 + 7 . 1 9 . 1 0 - 2

1 0 . 3 1 t 5 . 6 1 - 1 0-2

2 4 . 4 5 2 6 . 1 0 . 1 0-2

3 9 . 7 2 k 7 . 2 1 - 1 0-2

1 6 . 6 2 2 2 . 9 1 - l o - ’

2 5 . 4 2 i 6 . 2 4 . 1 0-2

4 0 . 7 3 t 7 . 1 1 * 1 O-’

5 . 7 0 2 1 . 8 1 - 1 0 - 2 7 . 8 6 2 3 . 1 0’1 0-2

1 0 . 5 2 i 4 . I 2 - 1 O-’

2 4 . 0 0 + 6 . 1 8 * 1 0 - 2 4 8 . 0 2 T 7 . 5 1 - l o - ’ 7 9 . 4 4 t 8 . 0 4 . 1 0-2

6 . 0 8 + 2 . 1 4 * 1

a Average v a l u e of e i g h t d e t e r m i n a t i o n s i s t a n d a r d d e v i a t i o n .

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

POTENTIOMETRIC TITRATIONS 769

Hydrazine- -1litrite ions

TABLE 2 Simultaneous Potentiometric Titration of Selenocyanates and Thio- cyanates with u-ODDD.

- H2NNH2 - NO2

14.00 16.00

Reductant Compounds

Selenocyanates-

-Thiocyanates SeCN- - SCN-

12.18 20.12

SeCN- - SCN- 12.03t3.21 - 1 0-2 20.1 526.24-1 0-2

Average value of eight determinations -+Standard Deviation a

TABLE 3 Simultaneous Potentiometric Titration of Hydrazine and Nitrite ions with p-ODDD.

Reduc tant Compounds

- H2NNH2 - NO2

14.03-+3 .08.10-2 16.06C4 -21 .I 0-2

Average value of eight determinations +Standard Deviation a

in the presence and in the absence trifluoroacetic acid are shown in

Table 4 .

These solutions were kept in dark bottles and the stability

of u-ODDD in acetonitrile solutions 1% in trifluoroacetic acid is

reasonable. Thus W-ODDD is superior to BTIB in this respect. + + ++ We had no interference from common ions such as K , Na ,Ca ,

++ Mg++, Ba , Al+++, NO;, PO:. Interferinq ions are those which parti-

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

770 PAPADOYANNIS AND GALLOS

~

Time

(Days)

TABLE 4 Experimental Results of the Stability Between Bis(trifluoroacet0xy) iodobenzene (BTIB) and u-0x0-ditrifluoroacetato-diphenyl-diiodine in the Presence and without Trifluoroacetic Acid.

-

Concentration of BTIB without

CF3COOH (mM)

5/55

5/43

5,21

4,91

4/61

4,50

4/10

3/98 I

Concentratio of BTIB with CF3COOH

(mM)

b

5,55

5,46

5,28

4,98

4,71

4 , 5 8

4,25

4,05

3/82 I I

JCF~COOHI =I% v/v

,oncentration J f p-ODDD

rithout CF3COOR

(mM)

5,55

5,53

5,52

5'25

5/06

4,80

4/62

4,50

4,38

:oncentration

gith CF3COOH -b ~f v-ODDD

(n-w

5,55

5/55

5,55

5,30

5/12

4 / 9 8

4/81

4/15

4,69

cipate in redox reactions, with p-oxo-ditrifluoroacetato-diphenyl-

diiodine . 2

ACKi4OWLEDGMENTS

The authors wish to thank Prof. A . Varvoglis, Laboratory of

Organic Chemistry,for helpful discussions.

REFERENCES

1 . Samara, C., Tapadoyannis, I., Kouimtzis, Tn., Spyroudis, S . and

Varvoylis, A.

Microchemical J. 1984 3 232.

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4

POTENTIOMETRIC TITRATIONS 7 7 1

2. Papadoyannis, I., Stratis, J. and Anthemidis, A.

Analytical Lett. 1984 17 (A1 3) 151 1.

3. Belcher, R., Liao, S, and Townshend, A.

Talanta 976 23 541.

4. Jacob, T and Nair, T.

Talanta 1972 19 347. 5. Pillai, V. and Wair, C.

Talanta 1875 22 57. 6. Gallos, J. 1984 ?h.D. Thesis, University of Thessaloniki,

Thessaloniki, Greece.

7. Gallos, J., Varvoglis, A. and Alcock, N., J. Chem. SOC., Perkin I,

In Press,

Received November 26, 1984 Accepted January 4, 1985

Dow

nloa

ded

by [

Uni

vers

ity o

f Il

linoi

s at

Urb

ana-

Cha

mpa

ign]

at 1

0:23

06

Oct

ober

201

4