Reaction of O,O-dialkyldithiophosphoric acid with N-tert-butyl-2,2-dihalopropanimines

Article abstract of DOI:10.1007/s11172-016-1422-z

O,O-Dialkyldithiophosphoric acid reacted with N-tert-butyl-2,2-dihalopropanimines to give iminium salt as a primary product, which further sequentially undergoes reaction with two equivalents of dithiophosphoric acid to initially reduce the C—X (X = Cl, Br) bond in the iminium salt and then nucleophilic replacement of the halogen atom with dialkoxydithiophosphate group. The final reaction products are the reduction—substitution product of the primary salt and bis(dialkoxythiophosphoryl) disulfide.

Full text of DOI:10.1007/s11172-016-1422-z

Russian Chemical Bulletin, International Edition, Vol. 65, No. 4, pp. 1119—1121, April, 2016
1119
Reaction of O,Oꢀdialkyldithiophosphoric acid
with Nꢀtertꢀbutylꢀ2,2ꢀdihalopropanimines
M. B. Gazizov, R. A. Khairullin, N. G. Aksenov, Yu. S. Kirillina, and A. Yu. Bandikova
Kazan National Research Technological University,
6
8 ul. K. Marksa, 420015 Kazan, Russian Federation.
Eꢀmail: mukattisg@mail.ru
O,OꢀDialkyldithiophosphoric acid reacted with Nꢀtertꢀbutylꢀ2,2ꢀdihalopropanimines to give
iminium salt as a primary product, which further sequentially undergoes reaction with two
equivalents of dithiophosphoric acid to initially reduce the C—X (X = Cl, Br) bond in the
iminium salt and then nucleophilic replacement of the halogen atom with dialkoxydithiophosꢀ
phate group. The final reaction products are the reduction—substitution product of the primary
salt and bis(dialkoxythiophosphoryl) disulfide.
Key words: dialkyldithiophosphoric acids, dichloropropanimine, dibromopropanimine, imiꢀ
nium salt, reduction of carbon—halogen bond, nucleophilic substitution of halogen, bisꢀ
(
dialkoxythiophosphoryl) disulfide.
1
Earlier, it has been shown that the reaction of O,Oꢀdiꢀ
alkyldithiophosphoric acid (1) with Nꢀalkylꢀ2ꢀhalogenꢀ
2
imine (2a), the equilibrium acid 1—chloroalkyliminium
salt 3a is strongly shifted to the right and the system does
not contain free acid, whereas in the case of bromoalkylꢀ
imine (2b), it is shifted to the left and the system contains
much free acid, which is involved in the reduction of the
C—Br bond in the iminium salt 3b. It is possible that the
conversion of imine 2 to iminium salt 3 increases the haloꢀ
philic properties of halogen, therefore, the reduction of
the C—Br bond occurs in the cation of the iminium salt 3,
rather than in the molecule of the starting imine.
We suggested that the introduction of additional elecꢀ
tronꢀwithdrawing substituent, for example, a halogen
atom, would affect the reactivity of the iminium cation.
Therefore, we studied the reaction of acid 1 with Nꢀtertꢀ
butylꢀ2,2ꢀdihalopropanimines 7, which was not described
earlier in the literature. We also suggested that in dihaꢀ
loimines 7 an additional electronꢀwithdrawing halogen
atom, first, would decrease the basic properties of the imiꢀ
ne nitrogen atom, shifting the equilibrium acid—salt to
ꢀmethylpropanimines (2) under mild conditions
–90—–60 °C) led to the formation of primary iminium
(
salts Nꢀalkylꢀ2ꢀhaloꢀ2ꢀmethylpropaniminium O,Oꢀdiꢀ
alkyldithiophosphates (3) (Scheme 1). Further transꢀ
formations of these salts depends on the nature of halogen
atom. In the case of Clꢀsubstituted salt 3a, the reaction
follows the pathway of nucleophilic substitution of a chloꢀ
rine atom by the dialkoxydithiophosphate group with the
formation of Nꢀalkylꢀ2ꢀ(dialkoxythiophosphorylthio)ꢀ2ꢀ
1
methylpropaniminium chloride (4) (Scheme 1, pathway a),
the Brꢀsubstituted salt (3b) reacts with another molecule
of acid 1 with the formation of Nꢀalkylꢀ2ꢀmethylpropanꢀ
iminium bromide (5) (the product of the reduction of the
C—Br bond) and bis(dialkoxythiophosphoryl) disulfide (6)
(
Scheme 1, pathway b).
The reason for this difference was found by dynamic
P—{ H} NMR spectroscopy: in the case of chloroalkylꢀ
31
1
2
Scheme 1
i
1
2
, 4, 6: R = Pr (a), Et (b)
: X = Cl (a), Br (b); 3: X = Cl (a), Br (b), R = Pr , Et
i
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1119—1121, April, 2016.
066ꢀ5285/16/6504ꢀ1119 © 2016 Springer Science+Business Media, Inc.
1

1
120
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 4, April, 2016
Gazizov et al.
Scheme 2
i
1
7
1
, 6: R = Pr (a), Et (b)
: X = Cl (a), Br (b)
2: X = Cl, R = Pr (a), Et (b); X = Br, R = Pr (c)
i
i
i. Reduction.
the left (this suggests the presence of free acid 1 in the
reaction mixture and its participation in the reduction of
the initially emerging salt 8), second, would increase the
halophilic properties of the latter (Scheme 2).
Experimental
1H and 13C—{ H} NMR spectra were recorded on an Avance
00WB spectrometer (400.13 and 100.61 MHz) in CDCl . Chemꢀ
1
4
3
The main products of the reaction of compounds 1 and 7
turned out to be disulfide 6 and Nꢀtertꢀbutylꢀ2ꢀhalopropanꢀ
iminium halide (13), the product of the reduction of the
C—X bond in 2,2ꢀdihalopropaniminium O,Oꢀdialkylꢀ
dithiophosphate 8, as well as Nꢀtertꢀbutylꢀ2ꢀ(dialkoxythioꢀ
phosphorylthio)propaniminium halide (12) (see Scheme 2).
Compounds 1 and 7 initially form the primary iminiꢀ
um salt 8, which further undergoes reduction process, folꢀ
lowing the halophilic elimination pathway upon treatment
ical shifts are given relative to SiMe , using signals of residual
4
protons or carbon nuclei of the deuterated solvent as a reference.
31
1
P—{ H} NMR spectra were recorded on Avance 400WB
161.98 MHz) and Bruker MSLꢀ400 (162 MHz) spectrometer,
(
chemical shifts for phosphorus nuclei are given relative to the
external standard 85% H PO .
3
4
Reaction of O,Oꢀdiisopropyldithiophosphoric acid 1a with
Nꢀtertꢀbutylꢀ2,2ꢀdichloropropanimine (7a), the ratio of 1 : 1 (A)
and 3 : 1 (B).
A. Dichloroimine 7a (6.13 g, 33 mmol) in CH Cl (10 mL)
–
2
2
with the (RO) PSS anion, which leads to the formation
2
was added dropwise to a solution of acid 1a (7.2 g, 33 mmol) in
of sulfenyl halide 9 and Cꢀanion 10, the protonation of
CH Cl (25 mL). The reaction mixture was allowed to stand for
2
2
which with acid 1 gives iminium dithiophosphate 11. The
31
1
2
4 h at room temperature. The P—{ H} NMR spectrum showed
–
(
RO) PSS anion in this salts is easily intercepted with
2
that the reaction mixture contained two organophosphorus comꢀ
pounds with δP 81.5 and 83.1 (65 : 35), disulfide 6a and Nꢀtertꢀ
butylꢀ2ꢀ(diisopropoxythiophosphorylthio)propaniminium chloꢀ
ride (12a). After evaporation of the solvent in vacuo, the residue
was treated with hexane, the crystals formed were filtered, washed
twice with ether, and dried to obtain crude Nꢀtertꢀbutylꢀ2ꢀchloꢀ
sulfenyl halide 9, forming disulfide 6 and salt 13. Another
direction of transformation of salt 11 includes nucleoꢀ
philic replacement of the halogen atom with dialkoxyꢀ
dithiophosphate anion, leading to the second final reacꢀ
tion product 12. When the reaction is carried out in the ratio
of 1 : 1, a part of the starting imine 7 is recovered without
changes, since acid 1 is additionally consumed in the formaꢀ
tion of disulfide 6 and derivative 12. For the ratio of comꢀ
pounds 1 and 7 equal to 3 : 1, only disulfide 6 and comꢀ
pound 12 were obtained. The individually isolated salt 13a
reacts with acid 1a with the formation of compound 12a.
To sum up, the initially emerging salt of acid 1 and
imine 7 Nꢀtertꢀbutylꢀ2,2ꢀdihalopropaniminium O,Oꢀdiꢀ
alkyldithiophosphate (8) reacts with the second molecule
of acid 1 to form disulfide 6 and Nꢀtertꢀbutylꢀ2ꢀhaloproꢀ
paniminium halide 13, which is an iminium salt reduced at
the C—X bond. Its reaction with another molecule of acid 1
leads to the product of substitution of a halogen atom with
the (dialkoxythiophosphorylthio)group, compound 12.
1
ropropaniminium chloride (13a) (1.4 g, 23%). H NMR of salt
1
3a (CDCl ), δ: 1.54 (s, 9 H, CMe ); 1.79 (d, 3 H, MeCH,
3
3
3
3
3
JH,H = 6.8 Hz); 5.71 (dq, 1 H, MeCH, J
= 6.8 Hz, J
= 8.8 Hz); 14.1 (br.s,
H,H
=
H,H
H,H
+
3
=
8.8 Hz); 8.45 (d, 1 H, CH=N , J
1 H, +NH). 13C—{1H} NMR (CDCl ), δ: 24.3 (s, HCMe); 27.81
3
+
(s, CMe ); 55.11 (s, HCCl); 61.16 (s, CMe ); 178.69 (s, CH=N ).
3
3
Found (%): C, 45.47; H, 8.13; N, 7.43; Cl, 38.38. C7H15Cl2N.
Calculated (%): C, 45.67; H, 8.21; N, 7.61; Cl, 38.51. Bis(diꢀ
isopropoxythiophosphoryl) disulfide (6a) (2.5 g, 35.7%) was obꢀ
tained from the hexane mother liquor by freezing out, m.p. 91 °C.
1
3
H NMR (CDCl ), δ: 1.40, 1.42 (both d, 24 H, Me CH, J
=
=
3
2
H,H
3
3
=
=
(
3
6.4 Hz); 4.90 (dhept, 4 H, CHOP, J
= 6.4 Hz, J
H,H
P,H
31
1
13
1
12.0 Hz). P—{ H} NMR (CDCl ), δ : 81.7. C—{ H} NMR
3
P
3
CDCl ), δ: 23.75 (d, CH ,
J
= 4.5 Hz); 23.57 (d, CH3,
= 6.7 Hz). Distillation of
3
3
P,C
2
JP,C = 5.5 Hz); 74.76 (d, CH, J
P,C
the mother liquor gave unreacted starting imine 7a (2.1 g, 34%),

t
Interaction of (RO) P(S)SH and MeCHal CH=NBu Russ.Chem.Bull., Int.Ed., Vol. 65, No. 4, April, 2016
1121
2
2
1
b.p. 45 °C (50 Torr). H NMR of imine 7a (CDCl ), δ: 1.23
15.3 mmol) in CCl (20 mL), keeping the temperature at –5—0 °C.
After standing of the reaction mixture for 3 h at 20 °C, the P—{ H}
3
4
31
1
(
s, 9 H, CMe ); 2.66 (s, 3 H, CMe); 7.81 (s, 1 H, CH=N).
3
B. A similar reaction of acid 1a (6.4 g, 30 mmol) in CH CI2
NMR spectrum exhibited one signal at δ 81.6 corresponding to
2
P
(
(
30 mL) and dichloroimine 7a (1.82 g, 10 mmol) in CH Cl2
10 mL) led to the isolation of Nꢀtertꢀbutylꢀ2ꢀ(diisopropoxyꢀ
disulfide 6a. The crystals formed were filtered, washed with benzꢀ
ene, and dried to obtain Nꢀtertꢀbutylꢀ2ꢀbromopropaniminium
bromide (13b) (1.8 g, 86%), m.p. 133—134 °C. H NMR
2
1
thiophosphorylthio)propaniminium chloride (12a) (2.8 g, 77%)
as a dense oil. H NMR (CDCl ), δ: 1.27 (d, 12 H, Me CH,
3
3
3
3
3
1
3
(CDCl ), δ: 1.62 (s, 9 H, CMe ); 2.02 (d, 3 H, Me, J
= 6.8 Hz);
3
2
3
3
H,H
3
3
JH,H = 6.4 Hz); 1.58 (s, 9 H,CMe ); 1.71 (d, 3 H, MeCH,
5.93 (dq, 1 H, CHBr, J
= 6.8 Hz, J
= 9.1 Hz); 8.42 (dd,
H,H
= 16.9 Hz); 14.91 (br.s, 1 H,
3
H,H
3
3
3
JH,H = 6.4 Hz); 4.78 (dhept, 2 H, CHOP, JH,H = 6.4 Hz,
1 H, CH=N, J
= 9.1 Hz, J
H,H
H,H
JH,H = 12.8 Hz); 5.07 (hept, 1 H, MeCH, 3J
= 6.4 Hz,
N H). Found (%): C, 30.61; H, 5.67; N, 4.98; Br, 58.37.
C H Br N. Calculated (%): C, 30.80; H, 5.54; Br, 58.52; N, 5.13.
+
H,H
JH,H = 7.2 Hz, 3JP,H = 12.4 Hz); 8.20 (d, 1 H, CH=N,
7
15
2
+
13
1
JH,H = 7.2 Hz); 16.2 (br.s, 1 H, NH). C—{ H} NMR
Volatile compounds and CCl were removed from the mother
4
3
(
2
CDCl ), δ: 23.52, 23.66 (both d, OCHMe , J = 5.04 Hz);
liquor in vacuo (0.02 Torr) into a trap cooled with liquid nitroꢀ
gen. The residue was recrystallized from hexane to obtain disulꢀ
fide 6a (2.85 g, 86%), m.p. 91 °C. Unreacted dibromoimine 7b
(1.8 g, 43% from the taken amount) was recovered from the
condensate in the trap by distillation, b.p. 58—60 °C (10 Torr).
B. A solution of dibromoimine 7b (2.7 g, 10 mmol) in CCl4
(10 mL) was added dropwise to a solution of acid 1a (4.3 g,
3
2
P,C
3
7.34 (s, CMe ); 28.07 (d, SCHMe, J
= 8.0 Hz); 51.94 (d,
P,C
3
2
CHS, J
3
= 4.5 Hz); 63.03 (s, CMe ); 74.75 (d, Me CHO,
3 2
JP,C = 8.5 Hz); 176.8 (s, CH=N ). P—{ H} NMR (CCl ),
P,C
+
31
1
4
δP: 83.2. Found (%): C, 43.40; H, 8.21; N, 4.01; P, 8.38.
C H ClNO PS . Calculated (%): C, 43.14; H, 8.08; N, 3.87;
P, 8.56. Disulfide 6a (1.8 g, 85%) was isolated from the mother
hexane liquor, m.p. 91 °C (hexane).
13
29
2
2
20 mmol) in CCl (10 mL) at 0 °C. The mixture was allowed to
4
Reaction of O,Oꢀdiethyldithiophosphoric acid (1b) with Nꢀtertꢀ
butylꢀ2,2ꢀdichloropropanimine (7a). A solution of imine 7a (1.0 g,
stand for 24 h at room temperature. The crystals formed were
filtered, washed with benzene, and dried to obtain Nꢀtertꢀbutylꢀ
2ꢀbromopropaniminium bromide (13b) (2.3 g, 85%), m.p.
133—134 °C. The mother liquor was concentrated in vacuo, the
residue was recrystallized from hexane to obtain disulfide 6a
(3.7 g, 86%), m.p. 91 °C.
5
.5 mmol) in CH Cl (5 mL) was added dropwise to a solution of
2 2
acid 1b (3.06 g, 16.4 mmol) in CH Cl (15 mL), keeping the
2
2
temperature of the reaction mixture at –10 °C. The mixture was
allowed to stand for 48 h at room temperature. The 3 P—{ H}
NMR spectrum of the mixture showed two resonance signals at
δP 84.3 and 86.1 attributed to the phosphorus atoms in comꢀ
pounds 6b and 12b. After evaporation of the solvent in vacuo, the
residue was thrice washed with hexane to obtain Nꢀtertꢀbutylꢀ2ꢀ
1
1
C. A solution of dibromoimine 7b (2.7 g, 10 mmol) in CH Cl
2
2
(15 mL) was added dropwise to a solution of acid 1a (6.4 g,
30 mmol) in CH Cl (25 mL). The reaction mixture was allowed
2
2
31
1
to stand for 48 h at room temperature. The P—{ H} NMR
spectroscopic data showed that the reaction mixture contained
(
(
diethoxythiophosphorylthio)propaniminium chloride (12b)
1
1.4 g, 77%) as a dense oil. H NMR (CDCl ), δ: 1.20, 1.18 (both
two organophosphorus compound with δ 81.4 and 83.2 attributed
3
P
3
t, 6 H, CH CH , J
CHCH , J
3
= 7.2 Hz); 1.40 (s, 9 H, CMe ); 1.53 (d, 3 H,
to the phosphorus atoms in disulfide 6a and Nꢀtertꢀbutylꢀ2ꢀ
(diisopropoxythiophosphorylthio)propaniminium bromide (12c).
After evaporation of the solvent in vacuo, the residue was washed
thrice with hexane to isolate crude Nꢀtertꢀbutylꢀ2ꢀ(diisopropꢀ
oxythiophosphorylthio)propaniminium bromide (12c) (2.68 g,
3
3
2
H,H
3
= 7.2 Hz); 4.84, 4.81 (both dquint, 1 H, CHCH ,
3
H,H
3
3
3
JH,H = J
= 7.2 Hz, J
= 7.8 Hz); 4.05, 4.06 (both quint,
H,H
P,H
3
3
4
3
H, POCH , J
= J
= 7.2 Hz); 8.25 (dd, 1 H, CH=N,
P,H
2
H,H
3
+
31
1
JH,H = 7.8 Hz, J
= 13.6 Hz); 15.19 (br.s, 1 H, N H). P—{ H}
H,H
1
NMR (CCl ), δ : 86.1. Found (%): C, 39.81; H, 7.78; N, 4.28;
66%) as a dense oil. H NMR (CDCl ), δ: 1.26 (d, 12 H, Me CH,
4
P
3
2
3
3
3
3
P, 9.49. C H CINO PS . Calculated (%): C, 39.57; H, 7.55;
N, 4.19; P, 9.58.
JH,H = 6.4 Hz); 1.51 (s, 9 H, CMe ); 1.66 (d, 1 H, CHMe,
JH,H = 5.6 Hz); 4.72 (dhept, 2 H, CHOP, JH,H = 6.4 Hz,
1
1
25
2
2
3
3
Reaction of Nꢀtertꢀbutylꢀ2ꢀchloropropaniminium chloride
13a) with O,Oꢀdiisopropyldithiophosphoric acid (1a). A solution
JH,H = 12.8 Hz); 4.95 (hept, 1 H, PSCH, 3J
= 5.6 Hz,
H,H
3
+
(
JH,H = 7.8 Hz, JP,H = 12.6 Hz);8.37 (dd, 1 H, CH=N H,
3J
= 7.8 Hz, J
3
= 16.8 Hz); 14.27 (br.s, 1 H, N H).
+
of acid 1a (1.26 g, 5.9 mmol) in CH Cl2 (5 mL) was added
2
H,H
H,H
dropwise to a solution of Nꢀtertꢀbutylꢀ2ꢀchloropropaniminium
chloride (13a) (1 g, 5.9 mmol) in CH Cl (10 mL) at 0 °C. After
This work was financially supported by the Ministry of
2
2
mixing the reagents, the reaction flask was slightly evacuated
90 Torr) to remove HCl liberated in the course of the reaction.
Education and Science of the Russian Federation (within
the Basic Part of State Assignment No. 2014/56).
(
Then, the reaction mixture was allowed to stand for 24 h at room
temperature. A crude Nꢀtertꢀbutylꢀ2ꢀ(diisopropoxythiophosꢀ
phorylthio)propaniminium chloride (12a) (1.45 g, 75%) was obꢀ
tained as a dense oil after evaporation of the solvent in vacuo.
References
1
31
1
13
1
1. M. B. Gazizov, R. A. Khairullin, N. G. Aksenov, Russ. Chem.
Bull. (Int. Ed.), 2014, 63, 2707 [Izv. Akad. Nauk, Ser. Khim.,
The H, P—{ H}, and C—{ H} NMR spectroscopic data of
compound 12a obtained by the reaction of Nꢀtertꢀbutylꢀ2ꢀchloꢀ
ropropaniminium chloride (13a) with O,Oꢀdiisopropyldithioꢀ
phosphoric acid (1a) and by the reaction of the latter with Nꢀtertꢀ
butylꢀ2,2ꢀdichloropropanimine (7a) are identical.
2
014, 2707].
2
. R. A. Khairullin, M. B. Gazisov, N. G. Aksenov, K. S. Gazisꢀ
ova, Yu. S. Kirillina, A. Yu. Bandikova, Vestnik KTU [Kazan
Techn. Univ. Bull.], 2015, 18, 7 (in Russian).
Reaction of O,Oꢀdiisopropyldithiophosphoric acid (1a) with
Nꢀtertꢀbutylꢀ2,2ꢀdibromopropanimine (7b), the ratio of 1 : 1 (A),
2
: 1 (B), 3 : 1 (C).
A. A solution of dibromoimine 7b (4.2 g, 15.3 mmol) in CCl4
Received July 22, 2015;
(
15 mL) was added dropwise to a solution of acid 1a (3.3 g,
in revised form December 24, 2015