Linear Bronsted-type behavior in the aminolysis of substituted naphthyl acetates

Article abstract of DOI:10.1002/1097-4601(200103)33:3<157::AID-KIN1009>3.0.CO;2-Y

The reactions of 4-acetyl-1-naphthyl acetate (1) and 6-acetyl-2-naphthyl acetate (2) with a series of amines of varying pK_a, viz. morpholine, ammonia, ethanolamine, glycine, n-butylamine, piperidine, hydrazine, imidazole, and hydroxylamine, are subjected to a kinetic investigation in aqueous medium, 30 °C, ionic strength 0.1 M (KCl). Pseudo-first-order rate coefficients (k_obs) are found under amine excess. The plots of (k_obs-k_H) against free amine concentration are linear at constant pH. The macroscopic nucleophilic substitution rate coefficients (k_N) are obtained as the slopes of these plots and found to be pH-independent for all the amines employed. The Bronsted-type plots obtained (log k_N against amine pK_a) for the aminolysis of both esters 1 and 2 are linear with slope values of β = 0.74 and β = 0.94, respectively. From these values, the kinetic law and the analysis of products, it is deduced that for both esters aminolysis proceed through a zwitterionic tetrahedral addition intermediate (T^±) whereby its dissociation into products is rate-limiting (k₂ step). Comparison of k_N values among them shows that both esters follow an identical mechanistic pathway with 1 having higher reactivity than 2, the reasons for which are discussed.

Full text of DOI:10.1002/1097-4601(200103)33:3<157::AID-KIN1009>3.0.CO;2-Y

A Linear Bro¨nsted-Type
Behavior in the Aminolysis
of Substituted Naphthyl
Acetates
D. RAJARATHNAM,1 P. ANANTHAKRISHNA NADAR2
1Department of Chemical and Environmental Engineering, The National University of Singapore, 4 Engineering Drive 4,
Singapore 117576
2Department of Chemistry, Annamalai University, Tamilnadu, India 608002
Received 15 May 2000; accepted 12 September 2000
ABSTRACT: The reactions of 4-acetyl-1-naphthyl acetate (1) and 6-acetyl-2-naphthyl acetate
(2) with a series of amines of varying pKa,viz. morpholine, ammonia, ethanolamine, glycine,
n-butylamine, piperidine, hydrazine, imidazole, and hydroxylamine, are subjected to a kinetic
investigation in aqueous medium, 30ЊC, ionic strength 0.1 M (KCl ). Pseudo-first-order rate
coefficients (kobs ) are found under amine excess. The plots of (kobs Ϫ kH) against free amine
concentration are linear at constant pH. The macroscopic nucleophilic substitution rate co-
efficients (kN) are obtained as the slopes of these plots and found to be pH-independent for
all the amines employed. The Bro¨nsted-type plots obtained (log kN against amine pKa) for the
aminolysis of both esters 1 and 2 are linear with slope values of ␤ ϭ 0.74 and ␤ ϭ 0.94,
respectively. From these values, the kinetic law and the analysis of products, it is deduced
that for both esters aminolysis proceed through a zwitterionic tetrahedral addition interme-
diate (TϮ) whereby its dissociation into products is rate-limiting (k2 step). Comparison of kN
values among them shows that both esters follow an identical mechanistic pathway with 1
having higher reactivity than 2, the reasons for which are discussed. ᭧ 2001 John Wiley & Sons,
Inc. Int J Chem Kinet 33: 157–164, 2001
INTRODUCTION
We have recently studied the kinetics and mecha-
nism of aminolysis of several substituted naphthyl ac-
etates in aqueous medium [37,38] and correlated the
macroscopic nucleophilic substitution rate coefficients
(kN) to the nature of the leaving group. The reaction
has been shown to occur through the pathways as
shown in Scheme I. The results obtained therein
showed that for the esters with better leaving group
(good nucleofuges) ammonolysis proceeds through a
zwitterionic tetrahedral addition intermediate (TϮ),
with its rate-determining formation (k1 step) and as-
sisted pathways of no kinetic significance. For the es-
ters with poor leaving group (poor nucleofuges), TϮ is
less unstable with k3[NH3] ϾϾ k2 and hence second-
order rate coefficients in amine are found and the re-
action proceeds through a general-base catalyzed path-
The aminolysis of aryl acetates has been the subject
of numerous kinetic studies. Specifically, extensive
works on the aminolysis reactions of phenyl acetates
[1–24] phenyl thiolacetates [25–28], and phenyl di-
thioacetates [29,30], in aqueous medium as well as in
partly aqueous medium [31–33] have been made, and
their mechanisms have been well established through
structure-reactivity correlation. In spite of a great deal
of information available on the aminolysis of phenyl
acetates, less is known about the mechanism of similar
reactions of naphthyl acetates [11,34–36].
Correspondence to: D. Rajarathnam (chedr@nus.edu.sg)
᭧ 2001 John Wiley & Sons, Inc.

158
RAJARATHNAM AND NADAR
Scheme I
way with an anionic tetrahedral intermediate (TϪ),
whereby the k3 step is rate-limiting. The pathway lead-
ing to cationic tetrahedral intermediate (Tϩ) through
general-acid catalysis is discarded in view of the non-
dependence of the rate constants on pH of the medium.
These results are consistent with earlier reported ones
[4,14], and the work has brought some light on the
influence of substituents on the relative nucleofugali-
ties of naphthoxide ions.
In order to investigate further on the mechanism of
the aminolysis of substituted naphthyl acetates and to
assess the influence of amine basicity, we perform in
the present work a kinetic study on the title reactions
in aqueous medium. The Bro¨nsted-type plots obtained
in the study are compared among them and to those
of similar ones of earlier reported works, and based on
that, a plausible mechanism is deduced.
were prepared shortly before the kinetic run by the
addition of calculated amounts of standardized hydro-
chloric acid or potassium hydroxide to the solutions
of known concentrations of amine-free base or amine
hydrochloride, as the case may be. At any fixed pH
value, the concentration of free amine was evaluated
using Eq. (1).
[N]T ·Ka
[N]F ϭ
(1)
Ka ϩ aHϩ
where [N]T is the total amine concentration, Ka is the
dissociation constant of the conjugate acid of the
ϩ
amine, and aH is the hydrogen ion activity. The pKa
of the conjugate acid of amines were determined from
measurements of the pH of partially neutralized solu-
tions under identical conditions to those of the kinetic
experiments [2,11].
EXPERIMENTAL
Materials
Kinetic Measurements
These were carried out in aqueous solution at 30.0 Ϯ
0.1ЊC, ionic strength 0.1 M (KCl), by monitoring spec-
trophotometrically the release of the corresponding na-
phthoxy ions of the substrates 1 and 2 at 248 and 271
nm, respectively. The initial ester concentration was
The 4-acetyl-1-naphthyl acetate and 6-acetyl-2-
naphthyl acetate were prepared from corresponding
naphthols [39,40] by procedures from the literature
[41]. Amines, with the exception of reagent-grade im-
idazole (Fluka) and glycine (BDH), were redistilled
from KOH or recrystallized shortly before use. Etha-
nolamine was simply redistilled.
5
(5–6) ϫ 10Ϫ M, and the amine concentration was
kept at several times excess over the substrate.
Pseudo-first-order rate coefficients (kobs) were
found throughout, by means of the method of Gug-
genheim [42], employing the least-squares technique.
The amines were employed as buffers to maintain
constant pH. The amine–amine hydrochloride buffers

¨
A LINEAR BRONSTED-TYPE BEHAVIOR IN THE AMINOLYSIS OF SUBSTITUTED NAPHTHYL ACETATES
159
1
1
The experimental conditions of the reactions and the
rate coefficients are given in Tables I and II.
was varied. (For 1, khyd ϭ 6.52 Ϯ 0.09 sϪ MϪ ; and
1
for 2, khyd ϭ 3.19 Ϯ 0.04 sϪ1 MϪ .)
In order to evaluate the results, the alkaline hy-
drolysis of esters was also followed spectrophotomet-
rically using known concentrations of potassium hy-
droxide. Ionic strength was maintained at 0.1 M, and
other experimental conditions were essentially the
same as those maintained for aminolysis. Alkaline hy-
drolysis of esters followed second-order kinetics and
the rate coefficients, khyd (where khyd ϭ kobs/[OHϪ]),
were unaffected when the hydroxide ion concentration
Product Studies
The product studies was carried out according to the
procedure already reported [37], based on the method
of Katz et al. [43], which showed in all the cases at
least 90% of the formation of amide product under the
experimental conditions.
Table I Summary of Experimental Conditions and Rate Coefficients for
the Aminolysis of 4-Acetyl-1-Naphthyl Acetatea
Ϫ1
Ϫ
Ϫ1
Amine
pH
103 [N]F/Mb
103 (kobs Ϫ kH)/s
k2Ј/s 1 M
Morpholine
8.22 11.10–16.03
8.37 13.91–20.09
8.57 17.98–25.96
8.81 22.82–32.96
4.52–6.30
5.61–7.71
6.71–9.18
7.83–11.07
1.57–1.92
1.77–2.22
2.16–2.62
2.60–3.04
5.27–8.72
6.19–10.30
7.55–12.38
9.34–15.09
2.82–6.88
3.98–8.68
4.81–10.42
6.42–13.64
2.66–8.03
3.13–9.65
4.30–12.09
5.73–15.78
3.28–7.17
4.71–9.99
6.78–14.85
10.54–18.52
1.79–2.60
3.35–5.33
5.44–8.81
7.19–12.25
3.22–5.59
4.06–6.95
4.93–8.39
5.73–9.63
3.20–5.20
3.94–6.18
4.63–7.26
5.36–8.59
0.39 Ϯ 0.03
0.39 Ϯ 0.02
0.36 Ϯ 0.02
0.33 Ϯ 0.01
0.92 Ϯ 0.02
0.84 Ϯ 0.01
0.85 Ϯ 0.02
0.86 Ϯ 0.01
1.69 Ϯ 0.03
1.68 Ϯ 0.02
1.66 Ϯ 0.02
1.68 Ϯ 0.03
2.58 Ϯ 0.11
2.80 Ϯ 0.16
3.06 Ϯ 0.20
3.36 Ϯ 0.19
10.81 Ϯ 0.91
8.60 Ϯ 0.76
8.41 Ϯ 0.82
7.47 Ϯ 0.91
19.53 Ϯ 0.88
18.40 Ϯ 0.71
22.75 Ϯ 0.93
23.02 Ϯ 0.81
5.33 Ϯ 0.01
4.60 Ϯ 0.07
5.13 Ϯ 0.09
4.16 Ϯ 0.09
2.14 Ϯ 0.05
2.24 Ϯ 0.02
2.39 Ϯ 0.04
2.59 Ϯ 0.03
3.53 Ϯ 0.01
3.54 Ϯ 0.07
3.47 Ϯ 0.03
3.57 Ϯ 0.06
Ammonia
9.21
9.38
9.55
9.73
9.54
9.67
9.85
10.04
9.33
9.47
9.57
9.69
9.94
10.15
10.30
10.51
10.12
10.29
10.42
10.57
6.40
6.77
6.95
7.21
7.12
7.29
7.43
7.55
6.04
6.21
6.44
6.68
1.51–1.87
1.83–2.31
2.10–2.65
2.36–2.87
2.89–4.92
3.39–5.78
4.08–6.96
4.75–8.11
0.98–2.46
1.22–3.06
1.40–3.50
1.62–4.05
0.24–0.45
0.34–0.66
0.43–0.84
0.58–1.12
0.15–0.22
0.21–0.31
0.27–0.40
0.35–0.53
0.34–0.49
0.77–1.18
1.14–1.65
1.97–2.86
1.51–2.60
1.80–3.10
2.00–3.51
2.21–3.78
0.91–1.57
1.09–1.76
1.31–2.10
1.47–2.39
Ethanolamine
Glycine
n-Butylamine
Piperidine
Hydrazine
Imidazole
Hydroxylamine
a In aqueous solution at 30.0 Ϯ 0.1ЊC, ionic strength 0.1 M (KCl). At least five runs
were carried out at each pH. The errors shown are standard deviations.
b Concentration of free amine.

160
RAJARATHNAM AND NADAR
Table II Summary of Experimental Conditions and Rate Coefficients for
the Aminolysis of 6-Acetyl-2-Naphthyl Acetatea
Ϫ1
Ј
Ϫ
Ϫ1
Amine
pH
103 [N]F/Mb
103 (kobs Ϫ kH)/s
k2/s 1 M
Morpholine
8.23 157.90–278.20
8.37 194.70–343.10
8.57 251.70–443.40
8.79 314.10–553.40
3.61–6.02
4.12–6.86
4.85–8.20
5.48–9.11
2.73–4.90
3.10–5.55
3.55–6.23
4.76–6.79
3.19–5.48
3.80–6.36
4.47–7.50
5.21–8.67
3.46–4.18
4.23–5.19
5.11–6.31
6.42–7.96
2.48–4.08
4.42–7.15
5.62–8.92
6.86–10.68
2.84–4.76
3.83–6.36
5.14–8.20
6.03–9.93
0.98–2.27
1.60–4.82
2.21–6.73
3.11–9.42
1.40–2.53
1.68–3.01
1.81–3.24
2.00–3.30
1.42–3.29
1.90–4.35
2.24–5.44
2.61–6.09
0.023 Ϯ 0.001
0.021 Ϯ 0.004
0.020 Ϯ 0.002
0.017 Ϯ 0.006
0.053 Ϯ 0.001
0.053 Ϯ 0.003
0.053 Ϯ 0.003
0.052 Ϯ 0.004
0.16 Ϯ 0.02
0.16 Ϯ 0.02
0.15 Ϯ 0.01
0.15 Ϯ 0.02
0.22 Ϯ 0.04
0.22 Ϯ 0.01
0.22 Ϯ 0.03
0.24 Ϯ 0.03
4.05 Ϯ 0.12
3.35 Ϯ 0.15
3.10 Ϯ 0.17
3.00 Ϯ 0.27
6.21 Ϯ 0.09
6.20 Ϯ 0.08
6.00 Ϯ 0.19
5.61 Ϯ 0.29
0.85 Ϯ 0.01
0.75 Ϯ 0.03
0.74 Ϯ 0.03
0.56 Ϯ 0.09
0.22 Ϯ 0.01
0.20 Ϯ 0.01
0.19 Ϯ 0.04
0.18 Ϯ 0.04
0.38 Ϯ 0.03
0.45 Ϯ 0.02
0.44 Ϯ 0.04
0.46 Ϯ 0.03
Ammonia
9.21
9.33
9.46
9.60
9.39
9.52
9.67
9.84
9.32
9.45
9.57
9.69
9.74
10.13
10.29
10.45
10.12
10.28
10.42
10.55
6.42
6.76
6.94
7.23
6.94
7.12
7.27
7.41
6.04
6.22
6.43
6.66
49.70–89.00
56.60–101.30
63.70–113.90
85.5–126.30
19.00–32.77
22.88–39.46
27.60–47.60
32.93–56.80
14.91–18.54
18.21–22.65
21.49–26.73
24.94–31.02
0.56–0.86
1.17–1.78
1.51–2.31
1.90–2.90
0.35–0.56
0.48–0.78
0.63–1.03
0.81–1.31
0.97–2.92
Ethanolamine
Glycine
n-Butylamine
Piperidine
Hydrazine
2.08–6.24
3.09–9.28
5.68–17.04
6.69–11.63
8.39–14.59
9.82–17.06
11.10–19.28
3.89–8.04
4.68–9.66
5.53–11.44
6.27–12.96
Imidazole
Hydroxylamine
a In aqueous solution at 30.0 Ϯ 0.1ЊC, ionic strength 0.1 M (KCl). At least five runs were
carried out at each pH. The errors shown are standard deviations.
b Concentration of free amine.
RESULTS AND DISCUSSION
almost constant within a given pH and are independent
of free amine concentration. The values of k2Ј are
given in Tables I and II. Further, the plots of log(kobs
Ϫ kH) against log[N]F for all the amines are linear with
unit slope (plots not shown). These indicate that ami-
nolysis of these esters depends only upon the first
power of the free amine concentration and the assist-
ance by a second molecule of amine is absent. Hence
the catalyzed pathway has no significance, and the re-
action proceeds through a pathway whereby a simple
unassisted attack of nucleophiles over esters prevails.
The pseudo-first-order rate coefficients (kobs ) observed
for the aminolysis of esters are converted to the ap-
parent second-order rate coefficients, k2Ј , where k2Ј ϭ
(kobs Ϫ kH)/[N]F, where kH is the product of khyd, the
second-order rate coeffcient for the alkaline hydrolysis
of esters and the concentration of hydroxide ion
present in the system for aminolysis, calculated from
aOHϪ and the activity coefficient of hydroxide ion [44].
In the aminolysis of esters, k2Ј values calculated are

¨
A LINEAR BRONSTED-TYPE BEHAVIOR IN THE AMINOLYSIS OF SUBSTITUTED NAPHTHYL ACETATES
161
Table III Macroscopic Nucleophilic Substitution Rate Coefficients, kN/sϪ1 MϪ1, for the
Aminolysis of 4-Acetyl-1-Naphthyl Acetate and 6-Acetyl-2-Naphthyl Acetatea
No. Amine
pKa
4-Acetyl-1-Naphthyl Acetate 6-Acetyl-2-Naphthyl Acetate
1.
2.
3.
4.
5.
6.
7.
8.
9.
Morpholine
Ammonia
Ethanolamine
Glycine
n-Butylamine
Piperidine
Hydrazine
Imidazole
Hydroxylamine
8.48 Ϯ 0.04
9.21 Ϯ 0.05
9.50 Ϯ 0.03
9.78 Ϯ 0.04
10.77 Ϯ 0.03
11.24 Ϯ 0.05
7.97 Ϯ 0.02
6.95 Ϯ 0.05
5.77 Ϯ 0.03
0.33 Ϯ 0.04
0.91 Ϯ 0.02
1.71 Ϯ 0.01
2.82 Ϯ 0.03
19.55 Ϯ 0.27
46.88 Ϯ 0.22
5.41 Ϯ 0.04
2.35 Ϯ 0.02
3.72 Ϯ 0.02
0.022 Ϯ 0.002
0.053 Ϯ 0.004
0.15 Ϯ 0.02
0.24 Ϯ 0.05
4.45 Ϯ 0.09
8.12 Ϯ 0.15
0.67 Ϯ 0.02
0.19 Ϯ 0.03
0.48 Ϯ 0.01
a Values of both pKa and kN in aqueous solution, at 30.0 Ϯ 0.1ЊC, ionic strength 0.1 M (KCl). The errors shown
are standard deviations.
The reactions subjected to the present investigation
can be kinetically described by Eqs. (2) and (3),
according to the order of amines given in Table III.
Expectedly, hydrazine and hydroxylamine deviate
from the plot owing to the ‘␣-effect’ [48,49] and im-
idazole because of its reactivity towards the esters as
a tertiary amine [1].
The values of the slopes are consistent with a step-
wise mechanism, where a zwitterionic tetrahedral ad-
dition intermediate (TϮ) is found on the reaction path-
way and its breakdown to products is rate-
determining.
Similar larger Bro¨nsted slope values (␤ ϭ 0.8–1.0)
have been found in the aminolysis of phenyl acetates
[50], 4-nitrophenyl acetate [4,17,48], 2,4-dinitro-
phenyl acetate [14], and 2-nitrophenyl acetate [24],
where a stepwise mechanism has been invoked with
the breakdown of TϮ to products being the rate-deter-
mining step. The slope values of the Bro¨nsted plots
above are also similar to those obtained in the ami-
d[ArOϪ]
ϭ (kobsϪkH)[Ester]
(2)
(3)
dt
(kobs Ϫ kH) ϭ ko ϩ kNFN[N]T
where ArOϪ is 4-acetyl-1-naphthoxide ion or 6-acetyl-
2-naphthoxide ion, kobs is the pseudo-first-order rate
coefficient, ko is the coefficient of assisted paths com-
prising general acid, general base, and specific base
assisted attack of amines, kN is the macroscopic nu-
cleophilic substitution rate coefficient, FN is the free-
amine fraction and [N]T is the concentration of total
amine (free-amine plus its conjugate acid). Since, FN
ϭ [N]F/[N]tot, Eq. (3) becomes,
(kobs Ϫ kH) ϭ ko ϩ kN[N]F
(4)
The values of ko and kN were obtained as the intercept
and slope, respectively, of plots of (kobs Ϫ kH) against
[N]F at constant pH, for at least four pH values. The
values of kN were found to be pH-independent over
the pH range employed, and the mean kN values are
given in Table III. For all the reactions, the value of
ko was negligible compared to the aminolysis term (kN)
in Eq. (4).
The pKa values of the amines employed and kN val-
ues were statistically corrected [45–47] before plot-
ting the Bro¨nsted-type equation. For both esters, the
plots are linear for the amines morpholine, ammonia,
ethanolamine, glycine, n-butylamine, and piperidine,
with slopes ␤ ϭ 0.74 (r ϭ 0.980) and ␤ ϭ 0.94 (r ϭ
0.980) for 1 and 2, respectively. The plots are shown
in Figures 1 and 2. The numbers given in the plots are
Figure 1 Bro¨nsted-type plot (statistically corrected) ob-
tained in the aminolysis of 4-acetyl-1-naphthyl acetate in
aqueous mediums, 30ЊC, ionic strength 0.1 M (KCL).

162
RAJARATHNAM AND NADAR
Figure 2 Bro¨nsted-type plot (statistically corrected) ob-
tained in the aminolysis of 6-acetyl-2-naphthyl acetate in
aqueous medium, 30ЊC, ionic strength 0.1 M (KCl).
Figure 3 Comparative plot of kN in the aminolysis of 4-
acetyl-1-naphthyl acetate (1) and 6-acetyl-2-naphthyl acetate
(2).
nolysis of phenyl thiolacetates in aqueous medium
[26,27].
k1k2
kN ϭ
(5)
Larger Bro¨nsted slope values have also been found
in the aminolysis of 4-nitrophenyl benzoate [51,52],
2,4-dinitrophenyl 4-chlorobenzoate [53], 2,4-dinitro-
phenyl 4-nitrobenzoate [54], and other reactive car-
bonyl compounds [55–59], where a stepwise mecha-
nism has been proposed with the breakdown of TϮ to
products being the rate-determining step.
(kϪ ϩ k2)
1
Since the large ␤ values for the present reactions sug-
gest that the second step of Scheme II is rate limiting,
it follows that kϪ ϾϾ k2 and hence Eq. (5) takes the
1
form,
k1k2
A smaller value of the Bro¨nsted slope (␤ ϭ 0.1–
0.3) has been found in the aminolyses of these esters
when the formation of a zwitterionic tetrahedral ad-
dition intermediate (TϮ) is rate determining [4,26,27].
According to the results and rate law obtained, the
analysis of products, and the Bro¨nsted-type plots
found for the reactions under investigation, the mech-
anism of these reactions can be described by Scheme
II, where Ar is either of the naphthyl moiety of esters
1 and 2 and N represents the amine employed. In
Scheme II, the k2 step is rate limiting.
kN ϭ
ϭ K1k2
(6)
kϪ
1
where K1 is the equilibrium constant for the first step.
The transition state for the aminolysis of these esters
may exist as shown in Structure 1.
The macroscopic nucleophilic substitution rate co-
efficient kN can be related to the microscopic rate co-
efficients of Scheme II through application of the
steady-state approximation to the tetrahedral interme-
diate, as in Eq. (5).
Structure 1
An analogous transition state and a similar rate equa-
tion with a pre-equilibrium step was proposed by Cas-
Scheme II

¨
A LINEAR BRONSTED-TYPE BEHAVIOR IN THE AMINOLYSIS OF SUBSTITUTED NAPHTHYL ACETATES
163
15. Castro, E. A.; Santander, C. L. J Org Chem 1985, 50,
3595.
16. Castro, E. A.; Ureta, C. J Org Chem 1990, 55, 1676.
17. Bond, P. M.; Castro, E. A.; Moodie, R. B. J Chem Soc,
Perkin Trans 2 1976, 68.
18. Deady, L. W.; Finlayson, W. L. Aust J Chem 1980, 33,
2441.
19. Deady, L. W.; Finlayson, W. L. Aust J Chem 1983, 36,
1951.
20. Do Amaral, L.; Koehler, K.; Bartenbach, D.; Pletcher,
T.; Cordes, E. H. J Am Chem Soc 1967, 89, 3537.
21. Kirsch, J. F.; Kline, A. J Am Chem Soc 1969, 91, 1841.
22. Kovach, I. M.; Belz, M.; Larson, M.; Rousy, S.;
Schowen, R. L. J Am Chem Soc 1985, 107, 7360.
23. Knowlton, R. C.; Byers, L. D. J Org Chem 1988, 53,
3862.
24. Arcelli, A.; Concilio, C. J Org Chem 1996, 61, 1682.
25. Hupe, D. J.; Jencks, W. P. J Am Chem Soc 1977, 99,
451.
26. Castro, E. A.; Ureta, C. J Org Chem 1989, 54, 2153.
27. Castro, E. A.; Ureta, C. J Chem Soc, Perkin Trans 2
1991, 63.
28. Ananthakrishna Nadar, P.; Jeyakumar, T. Indian J
Chem, Sect A 1994, 33A, 627.
tro et al. [54] in the pyridinolysis of 2,4-dinitrophenyl
4-nitrobenzoate with a Bro¨nsted slope of 0.9.
A comparative plot of esters 1 and 2 for kN values,
which is linear (r ϭ 0.990), is shown in Figure 3. This
indicates that for the aminolysis of these esters iden-
tical mechanism prevails irrespective of the position
of substituent in the naphthalene ring. However, the
reactivity of 1 is higher compared to 2 toward these
amines (Table III), which is reflected in a smaller ␤
value for 1, which is consistent with the earlier re-
ported works wherein smaller ␤ values were obtained
for more reactive esters [2,3,18]. Present observation
conforms with the earlier reports, which suggest that
the reactivity of 6-substituted naphthalene system is
largely decided by the 3,4-benzo substituent (with
larger ␴ values) rather than by the actual substituent
present [60,61]. Thus, for 2 the electron-withdrawing
effect of the acetyl group is less pronounced to reach
the reaction center, which makes the naphthoxide ion
act as a poor nucleofuge. Also, it makes the carbonyl
carbon less positive for an effective amine attack.
Therefore, it is probable that both K1 and k2 are smaller
for the reactions of 2.
29. Castro, E. A.; Ibanez, F.; Santos, J. G.; Ureta, C. J Chem
Soc, Perkin Trans 2, 1991, 1919.
30. Castro, E. A.; Ibanez, F.; Santos, J. G.; Ureta, C. J Org
Chem 1992, 57, 7024.
31. Castro, E. A.; Borquez, M. T.; Parada, P. M. J Org
Chem 1986, 51, 5072.
BIBLIOGRAPHY
32. Neuvonen, H. J Chem Soc, Perkin Trans 2 1987, 159.
33. Neuvonen, H. J Chem Soc, Perkin Trans 2 1995, 951.
34. Gordon, M.; Miller, J. G.; Day, A. R. J Am Chem Soc
1948, 70, 1946.
35. Gordon, M.; Miller, J. G.; Day, A. R. J Am Chem Soc
1949, 71, 1245.
36. Hawkins, P. J.; Piscalnikow, I. J Am Chem Soc 1955,
77, 2771.
37. Ananthakrishna Nadar, P.; Rajarathinam, D. Indian J
Chem, Sect A 1997, 36A, 749.
38. Ananthakrishna Nadar, P.; Rajarathinam, D. Indian J
Chem, Sect A 1998, 37A, 342.
39. Noller, C. R.; Adams, R. J Am Chem Soc 1924, 46,
1889.
40. Haworth, R. D.; Sheldrick, G. J Chem Soc 1934, 864.
41. Baliah, V.; Ganapathy, K. Trans Faraday Soc 1955, 77,
2771.
1. Jencks, W. P.; Carriuolo, J. J Am Chem Soc 1960, 82,
675, 1778.
2. Jencks, W. P.; Gilchrist, M. J Am Chem Soc 1968, 90,
2622.
3. Gravitz, N.; Jencks, W. P. J Am Chem Soc 1974, 96,
499, 507.
4. Satterthwait, A. C.; Jencks, W. P. J Am Chem Soc 1974,
96, 7018.
5. Cox, M. M.; Jencks, W. P. J Am Chem Soc 1978, 100,
5956.
6. Cox, M. M.; Jencks, W. P. J Am Chem Soc 1981, 103,
572, 580.
7. Fishbein, J. C.; Baum, H.; Cox, M. M.; Jencks, W. P. J
Am Chem Soc 1987, 109, 5790.
8. Bruice, T. C.; Mayahi, M. F. J Am Chem Soc 1960, 82,
3067.
9. Bruice, T. C.; Benkovic, S. J. J Am Chem Soc 1964,
86, 418.
10. Bruice, T. C.; Willis, R. G. J Am Chem Soc 1965, 87,
531.
42. Frost, A. A.; Pearson, R. G. Kinetics and Mechanism,
2nd ed.; Wiley: New York, 1961; Chapter 3.
43. Katz, J.; Liebermann, I.; Barker, H. A. J Biol Chem
1953, 200, 417.
11. Bruice, T. C.; Donzel, A.; Huffman, R. W.; Butler, A.
R. J Am Chem Soc 1967, 89, 2106.
12. Huffman, R. W.; Donzel, A.; Bruice, T. C. J Am Chem
Soc 1967, 89, 1973.
44. Kirsch, J. F.; Jencks, W. P. J Am Chem Soc 1964, 86,
833.
45. Bell, R. P. The Proton in Chemistry, 2nd ed.; Chapman
and Hall: London, 1973; Chapter 10.
13. Bruice, T. C.; Hegarty, A. F.; Felton, S. M.; Donzel, A.;
Kundu, N. G. J Am Chem Soc 1970, 92, 1370.
14. Castro, E. A.; Freudenberg, M. J Org Chem 1980, 45,
906.
46. Frost, A. A.; Pearson, R. G. Kinetics and Mechanism,
2nd ed.; Wiley: New York, 1961; Chapter 9.
47. Castro, E. A.; Moodie, R. B. J Chem Soc, Perkin Trans
2 1974, 658.

164
RAJARATHNAM AND NADAR
48. Edwards, J. O.; Pearson, R. G. J Am Chem Soc 1962,
84, 16.
55. Gresser, M. J.; Jencks, W. P. J Am Chem Soc 1977, 99,
6963, 6970.
49. Bruice, T. C.; Bruno, J. J.; Chou, W. S. J Am Chem Soc
1963, 85, 1659.
50. Johnson, S. L. Adv Phys Org Chem 1967, 5, 237.
51. Um, I. H.; Kwon, H. J.; Kwon, D. S.; Park, D. S. J Chem
Res (S) 1995, 301(M), 1801.
56. Castro, E. A.; Gil, F. J. J Am Chem Soc 1977, 99, 7611.
57. Palling, D. J.; Jencks, W. P. J Am Chem Soc 1984, 106,
4869.
58. Ferscht, A. R.; Jencks, W. P. J Am Chem Soc 1970, 92,
5442.
52. Campbell, P.; Lapinskas, B. A. J Am Chem Soc 1977,
99, 5378.
59. Hall, W. E.; Higuchi, T.; Pitman, I. H.; Uekama, K. J
Am Chem Soc 1972, 94, 8153.
53. Castro, E. A.; Valdivia, J. L. J Org Chem 1986, 51,
1668.
54. Castro, E. A.; Steinfort, G. B. J Chem Soc, Perkin Trans
2 1983, 453.
60. Fischer, A.; Packer, J.; Vaughan, J.; Wilson, A. F.;
Wong, E. J Org Chem 1959, 24, 155.
61. Packer, J.; Vaughan, J.; Wong, E. J Org Chem 1958,
23, 1373.