CH A PTER V I

KINETICS AND MECHANISM

OF OXIDATION OF HYDRAZOIC ACID BY

TETRABUTYLAMMONIUMTRIBROMIDE

Communicated to International Journal of Chemical Kinetics

Chapter-VI

118

6.1 Introduction:

The chemistry of azide has gained impetus in recent years due to its

powerful complexing properties.Hydrazoic acid is also known as hydrogen

azide or azoimide.It is courless, volatile. It is a compound of nitrogen and

hydrogen having formula HN3. The sodium azide is used for the preparation

of hydrazoic acid. It is a good nitrogen liberating agent, can be used in

organic synthesis including pharmaceuticals. It is used as a soil sterilizing

agent, fungicide and herbicide. Sodium azide is widely used as the

propellant in airbags. It is also useful in the preparation of agricultural

chemicals such as insecticide, fungicide, bactericide, wood preservative, and

herbicide. In biochemistry, it inhibits cytochrome oxidase by binding

irreversibly to the heme cofactor in a process similar to the action of carbon

monoxide. It is an enzyme inhibitor and nematocide. It is a useful indicator

and probe reagent. It is a cardiovascular agent and vasodilator agent.

Hydrazoic acid is a potentially hazardous compound due to its

explosive reactions and toxicity. It is one of the byproduct in the radioactive

waste of the nuclear reprocessing plants.[1] Its hazardous nature is reduced

by its oxidation in solution to compounds like nitrogen or nitrogen oxides. [2]

Such oxidations have been studied by various one electron and two-electron

oxidants in both alkaline and acidic medium.[3] The nature of electron

transfer in all the mechanisms is basically inner-sphere except [4] that by

IrCl62- and IrBr6

2-. The latter oxidations have been found to be outer-sphere

supported by application of Marcus cross relation. The oxidation of hydrazoic

acid by one electron oxidants proceeds by two one electron transfer steps

while by two electron oxidants both single electron or two electron transfer

steps have been proposed. The major product of oxidation is nitrogen and

nitrous oxide has also been reported during oxidation by peroxodisulfate.[5]

The oxidant chosen for this study is tetrabutylammonium

tribromide(TBATB) which is a salt of tribromide ion and has been used as

brominating [6] as well as oxidizing agent for organic [7, 8] and inorganic [9]

substrates. This reagent is more preferred than molecular bromine due to

the advantages like its solid nature, stability, selectivity and good product

yields. Since, the TBATB is a solid, it is comparatively less hazardous than

that of the volatile molecular bromine. The redox potential of TBATB is 1.0 V

Chapter-VI

119

thus making it a moderately strong two electron oxidizing agent. The product

of its reduction is bromide ion which can be effectively recycled through a

green process.[10] The organic oxidative transformations using TBATB

proceed with an inner-sphere mechanism involving prior complex formation

between the substrate [8,11] and the oxidant. The complex thus formed

decomposes into products through a rate determining two electron transfer

step. But in case of reactants like hydroquinone [12], the fast disproportination

of one electron transfer product hydroquinone radical, hinders the direct two

electron step even though the mechanism is inner-sphere in nature with

complex formation between the reactants. Therefore, the mechanism

between TBATB and hydrazoic acid would be an interesting study due to the

fact that both are prone to form complexes and both go through overall two

electron change. The mechanisms involving both reactants can undergo

either one or two electron transfer reactions. Hydrazoic acid is a hazardous

substance where as TBATB is less hazardous and the products of the

reaction between them, bromide and nitrogen, are non-hazardous which also

further justify the present study.

6.2 Experimental:

6.2.1 Materials and methods

All the chemicals used were of reagent grade and doubly distilled

water was used throughout. The oxidant TBATB was synthesized by the

reported procedure and stock solution was prepared by dissolving known

quantity of TBATB in 50% acetic acid. The standardization of TBATB was

carried out both by iodometrically and spectrophotometrically. The solution of

sodium azide (SD fine) was prepared by dissolving in distilled water. The

acetic acid (Thomas Baker) was distilled with usual method [13] and used.

Potassium bromide (SD fine) was used throughout the study as received.

6.2.2 Kinetic studies

The reaction mixture, in all kinetic runs, contained a constant quantity

of potassium bromide 0.01 mol dm-3 in order to prevent the dissociation of

tetrabutylammoniumtribromide. Kinetic runs were carried out under pseudo-

first-order conditions keeping large excess of hydrazoic acid. The solutions

containing the reactants and all other constituents were thermally

equilibrated at 25±0.1oC separately, mixed and reaction mixture was

Chapter-VI

120

analyzed for unreacted TBATB at 394 nm using Elico-SL-177

Spectrophotometer. The data of example run is given in (Table 6.1) and

corresponding pseudo-first-order plot is shown in (Fig. 6.1).

6.2.3 Product analysis

The quantitative measurement was not carried out for the nitrogen

(N2) gas evolved during progress of the reaction though its formation was

quantitatively established. The reaction was carried out at room temperature.

Evolution of N2 gas was confirmed by using Griess reagent test. [14] Sodium

azide (0.065g, 1 mmol) and TBATB (0.0482g, 0.1mmol) are taken in acetic

acid-water (1:1, V/V) mixture in the reaction flask and 1 gm of MnO2 was

added and the reaction flask is heated. The mouth of this flask was covered

with a disk of whatman filter paper moistened with the Griess reagent. A

reddish pink circle was developed on the whatman paper indicates the

evolution of nitrogen (N2) gas from the reaction mixture. (Griess reagent was

prepared by mixing equal volumes of 1% solution of sulfanilic acid in 30%

acetic acid and 1% solution of 1-Naphthylamine in 30% acetic acid).

6.2.4 Stoichiometry

The stoichiometry of the reaction was determined for different reaction

mixtures containing different concentration of hydrazoic acid with excess

concentrations of TBATB in 50% acetic acid-water mixture, which were kept

for 24 hours. The unreacted TBATB was determined spectrophotometrically

at 394 nm.It was found that one mole of TBATB reacted with two moles of

hydrazoic acid. The stoichiometry of the reaction is 1:2 as given in

equation1.

Br3- + 2HN3 - 3N2 + 2H+ + 3Br - (1)

6.3 Results:

6.3.1 Effect of reactants

The effect of oxidant, TBATB and reductant, hydrazoic acid were

studied at 25 oC. The [hydrazoic acid] and [oxidant] were varied from 5.0 x

10-3 to 5.0 x 10-2 mol dm-3 and 5 x 10-4 to 5 x 10-3 mol dm-3 at constant

[oxidant] 1.0 x 10-3 mol dm-3 and [Hydrazoic acid] 2.0 x 10-2 mol dm-3

respectively. The values of rate constants remained constant as the

concentration of oxidant is varied indicating first order dependence on the

Chapter-VI

121

oxidant concentrations, while the values of rate constants were found to

increase as concentration of reductant increased. (Table6.2).

6.3.2 Effect of solvent composition

The effect of solvent composition on rate of the reaction was carried

out by varying acetic acid content in the reaction mixture between 50 to 75%

V/V keeping all other concentrations constant .The pseudo-first-order rate

constant kobs decreases (Table6.3) as the acetic acid content increases.

6.3.3 Effect of added acrylonitrile

In order to understand the intervention of free radicals[15, 16], the

reaction was studied in presence of added acrylonitrile. There was no

induced polymerization of the acrylonitrile as there was no formation of

precipitate and also it did not affect the rate of the reaction between 0 to 8

%( v/v). The values of the rate constants are given in (Table 6.4).

6.3.4 Effect of temperature

The effect of temperature was studied at 15, 20, 25, 30 and 40 oC and

the rate constants, kobs and formation constant, K obtained are tabulated in

(Table 6.5 and 6.6).The activation parameters calculated are given in (Table

6.7).

6.4 Discussion:

6.4.1 Mechanism and rate law

The reaction was carried out under pseudo-first order conditions

keeping the concentrations of hydrazoic acid in large excess over TBATB in

50% acetic acid solutions and also containing a constant quantity of 0.01

mol dm-3 potassium bromide. The order in TBATB was unity as the pseudo-

first-order plot of log [TABTB] against time were linear upto more than three

half-life of the reaction in all the kinetic runs studied. The order in [hydrazoic

acid] was found to be near to unity (0.99) as found from log kobs against log

[hydrazoic acid] (Fig.6.2). Further the plot of 1/ kobs against 1/ [hydrazoic

acid] (Fig.6.3) was found to be linear with an intercept indicating involvement

of complex formation between the reactants. The oxidant, TBATB,

dissociates into a tetrabutylammonium ion and the tribromide ion in aqueous

acetic acid solution and further decomposition of the tribromide ion also

occurs [17] as shown in equilibrium (2) and (3) respectively.

Chapter-VI

122

(C4H9)4NBr3 (C4H9)4N+ + Br3

-(2)

Br3- Br2 + Br - (3)

The second equilibrium can be shifted to left side by using excess of

bromide ion in the solutions. The increase the acetic acid content in the

reaction mixture decreases the rate of the reaction considerably. This effect

of acetic acid might be due to the change in the dielectric constant of the

medium. The pH of the solution containing various quantities of acetic acid

was determined experimentally and found to be varies from 1.38 to 0.98 for

50% to 75% of acetic acid. Since, the salts of tribromide ions are strong

electrolytes in solution the possibility of their protonation is ruled out. The

ionization constant [18] of the hydrazoic acid, as shown in equilibrium

equation 4, is reported to be 4.17 x 10-5 mol dm-3 therefore, under the given

HN3 H+ + N3- K = 4.15 x 10-5 (4)

conditions, 50% acetic acid, of highest pH of 1.38 it exists as undissociated

HN3. Therefore, the tribromide ion of oxidant and undissociated hydrazoic

acid of the reactant are the active reactant species of the reaction.

The oxidation of azide ion, a two-electron reductant, in acidic medium

has been studied by both one-electron and two-electron oxidants. The

oxidation in acidic medium by one-electron oxidants like Co3+(aq) [19-21],

Mn3+(aq)[22-24], Ce4+(aq)[25], [Mn(bipy)OH]2+[26], [Ni(bipy)3]3+ [27],[Mn(edta)H2O]-

[28], [Co(III)W12O40]5-[29 and by two electron oxidant

ethylenebisbiguanidesilver(III)[28] has been reported. The mechanism

involving one-electron oxidants proceeds with the intervention of N3 free

radical, except in case of Mn3+(aq)[22], which is expected while in case of

Ag(III) complex[30] there remains the ambiguity whether N3 radical is

produced or not as there was no experimental evidence for formation of such

radical. The inverse dependence of rate of the reaction on the hydrogen ion

concentration is explained due to the protonation equilibira of the azide ion.

The stability of different complexes of azide ion with metal[30] ions and their

Chapter-VI

123

complexes between range 10-1 to 102 indicating variable degree of

coordination of the ion.

The redox potential of the Br3-/ Br- and Br3

-/ Br couples [31, 32], as

shown in equations (5) and (6), are 1.03 and 1.92 V respectively thus

making the later couple more stronger than the former one. The redox

potentials of N3-/N2 and N3

-/N3 couples. [30] as shown in equation (7) and (8),

are 3.1 and 1.3 V respectively. Therefore, the oxidation of hydrazoic acid by

tribromide ion through one electron transfer between them is

thermodynamically more feasible than the two electron transfer path way.

Further stoichiometry for formation of N2 requires two moles of hydrazoic

acid which leads to complex rate law in hydrazoic acid concentration. In the

present study no such complex rate law was observed and the plot

Br3- + 2e 3Br- (Eo = 1.03 V) (5)

Br3- + e Br2

- + Br- (Eo= 1.92 V) (6)

2HN3 + 2e 3N2 + 2H+ (Eo= 3.1 V) (7)

HN3 +e N3 + H+ (Eo=1.33 V) (8)

of 1/kobs against 1/[HN3] was found to be linear with an intercept as a result

of Michaelis-Menten type kinetics with a prior complex formation between

the reactants. Since, the reaction involve complex formation between the

reactants, the reaction proceeds through an inner-sphere path way. In order

to verify the complex formation experimentally the solutions of tribromide,

hydrazoic acid and the reaction mixture were analyzed

spectrophotometrically in 50% v/v acetic acid solutions between 250 to 450

nm (Fig.6.4). The spectrum of tribromide ion shows peak at 270 nm while

that of hydrazoic acid has very negligible absorbance at 270 nm. The

intensity of the peak at 270 nm of tribromide ion increases considerably

when hydrazoic acid is added to it which indicates formation of complex

between the both. The increase in intensity was also observed when both

hydrazoic acid or TBATB were increased at constant concentration of

Chapter-VI

124

TBATB or hydrazoic acid respectively, such type of complex [33] has also

been reported during oxidation of hydrazoic acid by bromine.

The initial products of oxidation of hydrazioc acid by two electron

oxidants is N3+ while for one electron oxidants it is N3 radical. In case of two

electron oxidation of hydrazoic acid the final product N2 is produced with the

reaction of N3+ with another hydrazoic acid species either before or after the

slow step of the reaction with the intervention of cyclic hexazine. Since, very

fast decomposition of hexazine intermediate does not contribute the redox

potential of the HN3/3N2 couple the two-electron change would thus require

a strong oxidizing agent. The oxidant used in the present study has the

moderate redox potential which does not oxidize the hydrazoic acid to an

hexazine intermediate. Generation of nitrogen, the final product, during one

electron oxidation of hydrazoic acid may occur by either fragmentation of N3

radical or combination of N3 radical with N3- forming N6

- followed by rapid

reaction with another oxidant or by the combination of N3 radical.

Fragmentation of N3 radical is thermoneutral as well as spin forbidden [26]

and the combination of N3 radical to form N6- leads to higher order

dependence on the concentration of oxidant. The formation of N6- has also

been not detected by pulse radiolysis study[34] however it has been

postulated kinetically and nanosecond laser flash photolysis study. [41-42] The

rate constant for the self combination reaction of N3 radical is reported [32] to

be 9.09 x 109 dm3mol-1s-1 and rate law would be simple.

Formation of azide complexes with both metal ions as well as with

anionic metal complexes has been well documented. [19-30] The stability of

complexes of azide ion with metal ions and their complexes between range

10-1 to 102 indicating variable degree of coordination of the ion. Although N3-

is kinetically more reactive than HN3 but HN3 is a weak acid which will be in

the undissociated form under the condition of the reaction formation of free

N3- is not possible. Therefore, under the reaction conditions the hydrazoic

acid is active species of the reductant.

The detailed mechanism of the reaction in terms of tribromide ion and

hydrazoic acid as the reactive species can be represented as Scheme 6.1.

The reaction is carried out in presence of excess of bromide ion which

suppresses the dissociation of tribromide ion and due to the high pH of the

Chapter-VI

125

solution the hydrazoic acid remains undissociated. The reaction is initiated

by the formation of complex between the reactive species of both the

reactants. The complex formation is both supported spectrophotometrically

and kinetically, as the plot of 1/kobs against 1/[HN3] is linear with an intercept.

The complex thus formed decomposes through one-electron redox slow step

to give radicals N3 and Br2-. The possibility of direct two-electron

decomposition of complex to generate N3+ and 3Br- redox step is ruled out

due to the thermodynamic feasibility of such a transformation as discussed

above.

Br3- + HN3 Br3N32- + H+

Kc (9)

Br3N32- Br2- + Br- + N3 kc (10)

Br2- + HN3 2Br- + N3 + H+ Fast (11)

2N3 3N2 Fast (12)

Scheme 1

Scheme 6.1

The formation of complex between tribromide ion and the hydrazoic acid

according to equation (9) of Scheme 6.1 generates hydrogen ion. Therefore,

increase in hydrogen ion concentration leads to decrease in the rate of the

reaction. In the present study the medium of the reaction is acetic acid which

acts as the source of hydrogen ion. The rate of reaction was found to

decrease as the acetic acid content increases. The pH of acetic acid

solutions was measured and the hydrogen ion concentration was calculated

using the determined pH values. The plot of 1/kobs against [H+] (Fig.6.5) was

found to be linear with an intercept suggesting existence of an equilibrium

generating hydrogen ion. The Br2- radical produced in step (10) of Scheme

6.1 will react with another molecule of hydrazoic acid in a fast step. The

redox potential of the couple Br2-/2Br- is reported to be 1.92 V [31] and that of

HN3/ N3 is 1.33 V [30 ] respectively. The equilibrium constant calculated on the

basis of redox potentials of the respective couples is found to be 9.5 x 109

dm3 mol-1 s-1 thus justifying the fastness of the step (10) of Scheme 6.1. The

rate law for the Scheme 6.1 can be derived as follows and the expression for

Chapter-VI

126

the kobs is given by equation (13). According to equation (13) the plot of

1/kobs against 1/ [HN3] and [H+] should be linear with intercepts and both the

plots are found to be so. Further from the intercept and slope of the plot of

1/kobs against 1/ [HN3] (Fig.6.3), the values of Kc and kc were calculated at

five different temperatures. The values of the activation parameters for the

slow step of the reaction were calculated from the plots of (-logk) against (1 /

T) Fig.6.6 and -log (k/T) against (1/T) Fig.6.7 and are given in (Table6.7).

The rate law obtained is simple which justify the mechanism proposed

without any intervention of hexazine cyclic intermediate.

Rate = kc [Br3N3]2- = kc Kc [Br3-]free [ HN3] / [H+]

[Br3-]total = [Br3-]free + [Br3N3]2- = [Br3-]free + Kc [Br3-]free [HN3] / [H+]

= [Br3-]free { ( [H+] + Kc [ HN3]) / [H+] }

[Br3-]free = [H+] [Br3-]total / ( [H+] + Kc [HN3] )

Rate = kcKc [Br3-]total [HN3] / ( [H+] + Kc[HN3] )

kobs = Rate / [Br3-]total = kcKc [ HN3] / ( [H+] + Kc[HN3] ) (13)

There was also no effect of added acrylonitrile[15], a free radical scavenger,

which conclusively does not rule out the possibility of free radical intervention

probably due to the rapidness of the reactions that these radicals

undergoing. The rate for the combination of N3 radical is very high and the

bromine free radical is a strong oxidant which undergo fast reaction with

HN3. The increase in the acetic acid content was found to decrease the rate

of reaction due to the equilibrium (9) of Scheme 6.1. The large negative

value of S# indicates the more ordered transition state, while the moderate

value of activation energy favours the proposed mechanism.

6.5 Conclusion:

The reaction between hydrazoic acid with tetrabutylammonium

tribromide was carried out in 50% aqueous acetic acid solution under

pseudo-first-order conditions keeping large excess of hydrazoic acid over

that of oxidant. The formation of complex between oxidant and substrate as

a result of electrophilic attack of Br3– ion on the nucleophilic nitrogen atom of

azide group (hydrazoic acid) is the rate determining step. The rapid

Chapter-VI

127

decomposition of complex takes place to give pure nitrogen gas as the

product.

Chapter-VI

128

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Chapter-VI

131

Table: 6.1 Sample run

Oxidation of Hydrazoic acid by TBATB in 50% acetic acid at 25oC.

102 [KBr] = 1.0 mol dm-3 , 102[Hydrazoic acid] = 2.0 mol dm-3.

Time (min) Absorbance at 394nm 103 [TBATB]

mol dm-3

Log (a/ a-x )

0 0.107 1.0 0.000

2 0.070 0.65 0.1842

4 0.045 0.42 0.3761

5 0.037 0.35 0.4611

6 0.030 0.28 0.5522

8 0.019 0.18 0.7505

10 0.012 0.11 0.9500

12 0.008 0.075 1.1260

14 0.005 0.047 1.33

16 0.003 0.028 1.55

18 0.002 0.019 1.62

Chapter-VI

132

Table: 6.2

Effect of reactant concentration on the oxidation of Hydrazoic acid by TBATB

in 50 % acetic acid-water medium at 25 0c.

102 [KBr] = 1.0 mol dm-3

103[TBATB]

mol dm-3

102[Hydrazoic acid ]

mol dm-3

103 kobs s-1

0.5 2.0 3.99

1.0 2.0 4.00

2.0 2.0 4.00

3.0 2.0 4.02

4.0 2.0 4.02

5.0 2.0 4.00

1.0 0.5 1.40

1.0 1.0 2.36

1.0 2.0 4.00

1.0 3.0 5.07

1.0 4.0 5.75

1.0 5.0 6.68

Chapter-VI

133

Table: 6.3

Effect of acetic acid content at 25 oC on oxidation of Hydrazoic acid by

TBATB.

103 [TBATB] =1.0 mol dm-3, 102[Hydrazoic acid] = 2.0 mol dm-3

102 [KBr] = 1.0 mol dm-3

%(V/V) Acetic acid pH 103kobs s-1

50 1.38 4.00

55 1.27 3.30

60 1.21 2.54

65 1.14 1.67

70 1.06 1.09

75 0..98 0.95

Chapter-VI

134

Table: 6.4

Effect of acrylonitrile concentration (% v/v) on the oxidation of

Hydrazoic acid by TBATB in 50% acetic acid at 25oC.

103 [TBATB] = 1.0 mol dm–3

102 [Hydrazoic acid] = 2.0 mol dm-3 102 [KBr] = 1.0 mol dm-3

% Acrylonitrile (v/v) 103kobs s-1

0 4.00

2 4.00

4 4.00

6 4.00

8 3.99

Chapter-VI

135

Table: 6.5

Effect of temperature on the oxidation of Hydrazoic acid by TBATB in 50%

acetic acid-water medium.

103 [TBATB] =1.0 mol dm-3, 102 [KBr] = 1.0 mol dm-3

102 [HN3]

Mol dm-3 288K 293K

103kobs

298K 303K 313K

0.5 0.72 1.16 1.40 2.34 4.72

1.0 1.75 1.54 2.36 3.11 7.46

2.0 2.00 2.30 4.00 4.55 9.17

3.0 2.56 3.08 5.08 6.10 12.35

4.0 2.88 3.85 5.75 7.46 15.62

5.0 3.32 5.38 6.67 9.17 18.52

Chapter-VI

136

Table: 6.6

Rate constants (kc) and formation constants (Kc) for the oxidation of

Hydrazoic acid by TBATB (Michaelis –Menten plot).

103 [TBATB] =1.0 mol dm-3 , 102 [KBr] = 1.0 mol dm-3.

Temperature 10 3 kc s-1 Formation

constant Kc

288K 7.32 21.52

293K 10.70 23.32

298K 14.57 24.55

303K 19.94 28.78

313K 27.67 38.60

Chapter-VI

137

Table: 6.7

Activation parameters for the oxidation of Hydrazoic acid by TBATB.

Ea

kJ mol-1

H#

kJmol-1

G#

kJ mol-1

- S#

J K-1 mol-1

39.9 15.42 62.16 156.88

Chapter-VI

138

Figure: 6.1

Plot of log (a / a-x) against time for oxidation of Hydrazoic acid by TBATB in

50% (v/v) in acetic acid at 25 0C.

(Conditions as in Table 6.1)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 5 10 15 20

Time (min)

log

( a

/ a-x

)

Chapter-VI

139

Figure: 6.2

Plot of -log kobs against -log [Hydrazoic acid].

1.5

1.6

1.7

1.8

1.9

2

2.1

2.2

2.3

2.4

2.28 2.38 2.48 2.58 2.68 2.78 2.88 2.98

- log k

-log

[Hyd

razo

ic a

cid]

Chapter-VI

140

Figure: 6.3

Michaelis-Menten plot for oxidation of Hydrazoic acid by TBATB.

(Conditions as in Table 6.5).

0

500

1000

1500

0 50 100 150 200 250

1/ [HN3]

1 /

kobs

288

293

298

303

313

Chapter-VI

141

Figure: 6.4

UV-Visible Spectra for the verification of complex formation between

Hydrazoic acid and TBATB.

a) 103 [TBATB] = 0.0 mol dm-3 +102 [Hydrazoic acid] = 2.0 mol dm-3 + 102

[KBr] = 1.0 mol dm-3 in 50% acetic acid-water medium

b) 102 [Hydrazoic acid] = 0.0 mol dm-3 + 103 [TBATB] = 1.0 mol dm-3 +102

[KBr] = 1.0 mol dm-3 in 50% acetic acid-water medium

c) 103 [TBATB] = 1.0 mol dm-3 +102 [Hydrazoic acid] = 2.0 mol dm-3 +

102 [KBr] = 1.0 mol dm-3 in 50% acetic acid-water medium

0

0.5

1

1.5

2

2.5

250 300 350 400 450

Wavelength(nm)

Abs

orba

nce

c

b

a

Chapter-VI

142

Figure: 6.5

Plot of 1/ kobs against [H+] for the oxidation of Hydrazoic acid by TBATB. (Conditions as in Table 6.3)

0

2

4

6

8

10

12

4 6 8 10 12

102[H+]

102 (1

/ k o

bs)

Chapter-VI

143

Figure: 6.6 Arrhenius plot for oxidation of Hydrazoic acid by TBATB.

[Plot of (-log k) against (1/ T)].

1.5

1.7

1.9

2.1

2.3

2.5

3.2 3.25 3.3 3.35 3.4 3.45 3.5

103 (1/ T )

-log

k

Chapter-VI

144

Figure: 6.7 Eyring plot for oxidation of Hydrazoic acid by TBATB.

[Plot of -log (k / T) against (1 / T)].

4

4.2

4.4

4.6

4.8

3.2 3.25 3.3 3.35 3.4 3.45 3.5

103(1/T )

-log

(k /

T )

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