Kinetics and mechanism of N-chloromethylamine decomposition in solutions

Article abstract of DOI:10.1134/S0036024416030225

Kinetics of N-chloromethylamine decomposition in an aqueous base medium and chloroform at different temperatures is studied. The decomposition of N-chloromethylamine is found to obey a second order equation in an aqueous base medium at an equimolar ratio of the reagents and a first order equation in chloroform with excess base. The activation energy of N-chloromethylamine decomposition in the both solvents is determined. A mechanism for the reaction is proposed. N-Chloromethylamine is shown to have approximately equal stability in these solvents within the studied temperature range.

Full text of DOI:10.1134/S0036024416030225

ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2016, Vol. 90, No. 3, pp. 541–544. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © V.V. Kuznetsov, M.D. Vedenyapina, M.I. Pleshchev, S.B. Gashev, N.N. Makhova, A.A. Vedenyapin, 2016, published in Zhurnal Fizicheskoi Khimii,
2
016, Vol. 90, No. 3, pp. 350–354.
CHEMICAL KINETICS
AND CATALYSIS
Kinetics and Mechanism of N-Chloromethylamine Decomposition
in Solutions
a
a, b
a
a
V. V. Kuznetsov , M. D. Vedenyapina , M. I. Pleshchev , S. B. Gashev ,
a
a, b
N. N. Makhova , and A. A. Vedenyapin
a
Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia
b
Moscow Technological Institute, Moscow, 117292 Russia
e-mail: mvedenyapina@yandex.ru
Received April 14, 2015
Abstract—Kinetics of N-chloromethylamine decomposition in an aqueous base medium and chloroform at
different temperatures is studied. The decomposition of N-chloromethylamine is found to obey a second
order equation in an aqueous base medium at an equimolar ratio of the reagents and a first order equation in
chloroform with excess base. The activation energy of N-chloromethylamine decomposition in the both sol-
vents is determined. A mechanism for the reaction is proposed. N-Chloromethylamine is shown to have
approximately equal stability in these solvents within the studied temperature range.
Keywords: N-chloromethylamine, kinetics and mechanism of decomposition, stability of N-chloromethyl-
amine.
DOI: 10.1134/S0036024416030225
INTRODUCTION
N-Halogenalkylamines are highly reactive com-
pH > 10 or рН < 4. In [13], the decomposition of iso-
meric N-chlorobutylamines in an aqueous solution
with excess of NaOH in the temperature range of 25–
pounds widely used in organic synthesis [1, 2]. For
example, N-halogenalkylamines can be added to ole-
fines giving β-halogenalkylamines [3]. A convenient
method for preparation of carbonyl compounds from
N-halogenmonoalkylamines by transforming N-halo-
genalkylamine groups into imine groups with its sub-
sequent hydrolysis was developed in [4–6]. N-Halo-
4
5°C was studied via spectrophotometry, and the
order and activation energy of the reaction were deter-
mined. According to the reaction mechanism pro-
posed in [12, 13], aldimine is formed at the first stage
of N-chlorobutylamine decomposition; it then
hydrolizes to butanal. The first stage is a limiting one:
genalkylamines are now actively used as aminating C H CH NHCl + NaOH → C H CH=NH + NaCl
3
7
2
3
7
reagents for C–N bond formation via the metal-cata-
lyzed activation of C–H bonds. A method for synthe-
sizing o-anilines through the Rh(III)-catalyzed direct
C–H amination of acetophenones [7] and pyvaloyloxy-
benzamides [8] has been developed. Methods of
amine synthesis based on the Сu(II)-catalyzed cross-
coupling of N-chloroalkylamines with aldehydes [9]
+
Н О (slowly), (а)
2
C H CH=NH + H O → C H CHO +NH (quickly).
3
7
2
3
7
3
The field of our long-term scientific and practical
interests includes the use of N-chloroalkylamines as
electrophilic aminating reagents for the synthesis of
N-alkylsubstituted diaziridines, which proved to be
unique both in organic synthesis and the study of
nitrogen stereochemistry [14–22]. Considering the
low stability of N-chloroalkylamines, the synthesis of
diaziridines is performed in the temperature range of
and MnO -promoted coupling of N-chloroalkylamines
2
with methylarenes were proposed in [10]. A method for
synthesizing tertiary amines through the Ni(II)-cata-
lyzed cross-coupling of N-chloroalkylamines with
organozinc compounds was developed in [11].
0–5°С in aqueous media [14, 16, 17, 19, 21], or in the
One great disadvantage of N-chloroalkylamines is range of 16–25°С in organochlorine solvents [18, 20].
their low stability under ambient conditions; however, There were no studies of N-chloroalkylamines thermal
there are few works devoted to their stability. A photo- stability prior to these. The aim of this work was to eval-
metric study of decomposition for N-chloroalkyl- uate N-chloromethylamine (1) stability as the first
amines and N-chloroalkylaminoalcohols in aqueous homologue of the N-chloroalkylamine series under
media at 25°C and pH 4–12 was described in [12]. conditions of diaziridine synthesis in a basic aqueous
Their rate of decomposition was found to be nearly and chloroform media in the temperature range of 0–
constant in the pH range of 7–10 and increases at 30°С.
541

5
42
KUZNETSOV et al.
сt/c0
1
.0
.8
.6
.4
.2
0
0
0
0
1
2
3
4
0
500
1000
1500
t, min
Fig. 1. Kinetics of N-chloromethylamine 1 decomposition in an aqueous base medium at (1) 2, (2) 8, (3) 14, and (4) 19°C.
1
EXPERIMENTAL
NMR Н spectrum (CDCl + CHCl = 1 : 1, δ,
3
3
ppm): 2.96 СН (br.s., 3Н); 4.25 NH (br.s., 1Н).
3
NaOCl Synthesis
13
NMR С spectrum (CDCl + CHCl = 1 : 1, δ,
3
3
Chlorine (7.1 g, 0.1 mol) was bubbled through a
ppm): 44.95 СН3.
solution of 8.8 g (0.22 mol) of NaOН in 50 mL of
water at 0–5°C under vigorous stirring. The yield of
Dry fine potash powder (20 g, 0.145 mol) was added
NaOCl determined via iodometric titration [23] was to the solution and it was thermostatted under slow stir-
9
4
8–100%. The resulting NaOCl solution was stored at ring at 5, 17, and 30°С. The aliquots for determining the
°C for no more than 1.5 h.
content of compound 1 were taken at specific time
intervals. The thermostatting time was 8 h.
Synthesis of МеNНСl (1) in a Basic Aqueous Medium
RESULTS AND DISCUSSION
Cooled NaOCl solution (0.1 mol) was slowly added
The drop in the concentration of 1 over time in a
dropwise to a solution of МеNH (0.1 mol) in water
2
basic aqueous medium at temperatures of 2, 8, 14, and
(
33 mL) at 0–5°C under vigorous stirring. The yield of
1
9°C is shown in Fig. 1. In [12], the hydrolysis of chlo-
compound 1 (85%) was determined via iodometric
titration [23]. The solution of compound 1 was thermo-
statted at 2, 8, 14, and 19°С, with aliquots for determin-
ing the content of compound 1 being taken at specific
time intervals. The thermostatting time was 25 h.
roalkylamines was found to be a bimolecular reaction
proceeding by the path (a). In [13], it was established
that the kinetics of N-chlorobutylamine hydrolysis can
be described by a first order equation. This order, quite
low for a bimolecular reaction, can be explained by the
reaction conditions (i.e., an excess of alkali), so the
change in the alkali concentration was negligible.
Solution of Compound 1 in Chloroform
In our experiments, the initial N-chloromethyl-
amine 1 : NaOH ratio was close to equimolar. We
would therefore expect the order of the hydrolysis
reaction to be close to second. If the change in NaOH
concentration is expressed in terms of the change in
the concentration of compound 1, the kinetic equa-
tion does indeed take the form
The preparation technique differed from the one
above by the addition of 3.0 g NaHCO at the chlori-
3
nation stage and saturation with NaCl at a tempera-
ture no higher than 5°С. МеNНСl was extracted with
8
0 mL of chloroform cooled to 0°С. The solution was
dried for 5 min over СаСl at 0–5°С, and then filtered.
2
The content and yield of compound 1 (0.075 mol,
(1– x)]n,
(1)
7
5%) were determined by iodometric titration [23].
dС
t
/dt = –k[С
0
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A
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2016

KINETICS AND MECHANISM OF N-CHLOROMETHYLAMINE DECOMPOSITION
сt /c0
543
lnk
1.0
0.9
0.8
0.7
−4
−5
−6
−7
3
2
1
3.3
3.4
3.5
3.6
03/T, K−1
1
0
100
200
300
400
500
t, min
Fig. 2. Rate of N-chloromethylamine 1 decomposition in
an aqueous base medium (s) and in chloroform (d) as a
function of temperature.
Fig. 3. Kinetics of N-chloromethylamine 1 decomposition
in chloroform at (1) 3, (2) 17, and (3) 30°C.
–1
where k is the reaction rate constant, n is the summa- where k is the reaction rate constant (min ) and С is
1 t
rized reaction order, С is the current concentration of the 1 concentration at moment t (min). After integra-
t
compound 1, С is the initial concentration of com- tion, Eq. (3) takes the form
0
pound 1, and x is the degree of compound 1 conver-
sion. The integrated form of Eq. (1) is
−
k1t
C
= C
e
.
(4)
t
0
(
n−1)
1/(n−1)
The experimental С –t dependences are well approxi-
(2)
t
C /C = 1/(k(n −1)С
t + 1)
t
0
0
.
mated by Eq. (4), the correlation coefficients being
close to 1 (Table 1, Fig. 3).
Using the minner program built into the Mathcad soft-
ware, the parameters of Eq. (2) were calculated by opti-
mizing the rate constant k values and reaction order n.
The calculated values are presented in Table 1. The reac-
tion order was found to be 2.04 ± 0.02. The high correla-
tion coefficients of this approximation indicate that the
decomposition of compound 1 proceeds according to a
pseudosecond order, judging from the bimolecularity of
the reaction. The activation energy was calculated from
the temperature dependence of the reaction rate constant
The reaction activation energy (84.2 kJ/mol) was
calculated from the temperature dependence of the 1
decomposition rate constant in chloroform (Table 2),
this value being almost equivalent to the one in the
aqueous base medium (83.5 kJ/mol). In addition,
both values are close to the activation energies of iso-
meric N-chlorobutylamines decomposition in an
excess of alkali [13]: 85.2, 86.0, 78.3 kJ/mol for
N-chloro-n-butylamine, N-chloro-iso-butylamine,
and N-chloro-sec-butylamine, respectively. The dif-
ference between the activation energies is obviously
associated with the differences between the structure
of alkyl radicals in N-chloroalkylamine molecules.
The data obtained upon the decomposition of
N-chloromethylamine 1 are consistent with the mech-
(
Fig. 2), its value being 83.5 kJ/mol.
The drop in the compound 1 concentration upon
thermostatting in chloroform and in the presence of an
excess of base is shown in Fig. 3. The kinetic curves
were analyzed by assuming that the reaction occurs
according to a pseudofirst order:
dС /dt = –k С ,
(3) anism of chloroamine decomposition given in [12, 13]:
t
1
t
HN
NH
H
N
H
N
H
H
H
N
H
Cl
Cl
H
N
OH
4
H
H
CH2 NH
—H2O
—Cl
Me
Cl
3
OH
1
HCHO + NH3
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 90 No. 3 2016

5
44
KUZNETSOV et al.
Table 1. Kinetic parameters for compound 1 decomposi-
2. I. V. Koval’, Russ. J. Org. Chem. 34, 757 (1998).
tion in an alkali medium at different temperatures.
3
. A. N. Mirskova, T. I. Drozdova, G. G. Levkovskaya,
and M. G. Voronkov, Russ. Chem. Rev. 58, 250 (1989).
R2
Т, °C
k, L/(mol min)
n
4
. W. H. Dennis, L. A. Hull, and D. H. Rosenblatt, Org.
2
8
5.49 × 10−4
1.38 × 10−3
3.84 × 10−3
4.70 × 10−3
2.02
2.07
2.07
1.98
0.999
0.998
0.998
0.995
Chem. 32, 3783 (1967).
5. P. Kovacic and M. K. Lowery, Org. Chem. 34, 911
(1969).
1
4
6
. J. M. Antelo, F. Arce, D. Casal, et al., Tetrahedron 45,
955 (1989).
. C. Grohmann, H. Wang, and F. Glorius, Org. Lett. 14,
56 (2012).
19
3
7
6
Table 2. Kinetic parameters of compound 1 decomposition
in chloroform at different temperatures.
8. Ka-Ho Ng, Z. Zhou, and Wing-Yiu Yu, Chem. Com-
mun. 49, 7031 (2013).
Т, °C
k , min−1
n
R2
1
9
. R. Cadoni, A. Porcheddu, G. Glacomelli, and
L. de Luca, Org. Lett. 14, 5014 (2012).
3
8.3 × 10−4
4.5 × 10−3
2.7 × 10−2
1.0
1.0
1.0
0.988
0.991
0.989
1
0. R. Vanjari, T. Guntreddi, and K. N. Singh, Org. Lett.
5, 4908 (2013).
1. T. J. Barker and E. R. Jarvo, J. Am. Chem. Soc. 131,
5598 (2009).
2. J. M. Antelo, F. Arce, and M. Parajo, J. Phys. Org.
Chem. 9, 447 (1996).
1
17
1
3
0
1
1
Methyleneimine 3 is formed at the first stage of 1
decomposition with a base. According to [13], methy-
leneimine then trimerizes into simple hexahydrotri-
azine 4. The hydrolysis of compound 3 to formalde-
hyde and ammonia is also possible [13]. According to
1
3. J. M. Antelo, F. Arce, M. C. Castro, et al., Int. J. Chem.
Kinet. 27, 703 (1995).
1
4. R. Ohme, E. Schmitz, and P. Dolge, Chem. Ber. 99,
2104 (1966).
1
5. E. Schmitz, in Three-Membered Rings with Two Hetero-
[
24], the interaction between these compounds also
atoms, Advances in Heterocyclic Chemistry, Vol. 24,
Ed. by A. R. Katritzky (Academic, New York, San
Francisco, Londo, 1979), p. 63.
leads to the formation of compound 4.
It should be noted that possibility of methylenei-
mine3formationupondecompositionofN-chlorome-
thylamine 1 in chloroform with potash has also been
confirmed by the data obtained by some authors. In
1
6. V. V. Kuznetsov, N. N. Makhova, Yu. F. Strelenko, and
L. I. Khmel’nitskii, Russ. Chem. Bull. 40, 2496 (1991).
1
7. V. V. Kuznetsov, N. N. Makhova, and L. I. Khmel’nitskii,
[
25, 26], 3 was found to be formed from 1 in the gas
Russ. Chem. Bull. 46, 1354 (1997).
phase with solid КОН or tert-BuOK at 50°C and
1
8. N. N. Makhova, A. N. Mikhailyuk, V. V. Kuznetsov,
–3
1
residual pressure of 10 mm Hg. H NМR studies
confirm that compound 3 is formed in chloroform
solution of 1 with potash at room temperature [27].
et al., Mendeleev Commun., 182 (2000).
1
9. V. V. Kuznetsov, S. A. Kutepov, N. N. Makhova,
K. A. Lyssenko, and D. E. Dmitriev, Russ. Chem.
Bull. 52, 665 (2003).
According to the kinetic data, there is only a slight
difference between the stability of N-chloromethyl-
amine 1 at close temperatures in aqueous base media
and chloroform. Thermostatting compound 1 for
2
0. V. V. Kuznetsov, N. N. Makhova, D. E. Dmitriev,
et al., Mendeleev Commun., 116 (2005).
2
1. V. V. Kuznetsov, V. B. Ovchinnikova, V. P. Ananikov,
and N. N. Makhova, Russ. Chem. Bull. 55, 2056
(2006).
9
0 min in the range 17–19°С results in an approxi-
mately 30% degree of decomposition in both reaction
media (curve 4 in Fig. 1 and curve 2 in Fig. 3). In both
cases, the half-decomposition time (τ ) 1 in this tem-
2
2. N. N. Makhova, V. Yu. Petukhova, and V. V. Kuznetsov,
1/2
ARKIVOC B, 128 (2008).
perature range is about 3 h. A similar scenario is
observed at other temperatures. Since the synthesis of
N-alkylaziridines in chloroform at 18–25°C with
yields of approximately 50% and higher was described
2
3. V. A. Shapovalova, Pharmaceutical Analysis of Drugs
(
Rubikon, Kharkov, 1995), p. 111 [in Russian].
24. T. Yoshitomo, WO Patent No. 2014069668 (2014).
25. H. Bock and R. Dammel, Chem. Ber. 120, 1961 (1987).
26. J.-C. Guillemin and J.-M. Denis, Tetrahedron 44,
[
18, 20], such synthesis is likely to succeed at this tem-
perature in basic aqueous media.
4
431 (1988).
2
7. V. V. Kuznetsov, J. S. Syroeshkina, D. I. Moskvin,
REFERENCES
et al., J. Heterocycl. Chem. 45, 497 (2008).
1
. P. Kovacic, M. K. Lowery, and K. W. Field, Chem.
Rev. 70, 639 (1970).
Translated by D. Yakusheva
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A
Vol. 90
No. 3
2016