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1STUDY OF FRAGMENTATION OF BIS-CARBMATE MEE-2 INTO FRAGMENT IONS IN THE LIQUID CHROMATOGRAPHY-MASS SPECTRUM
1Eldor Mashaev, 2Abduhamid Makhsumov, 3Ibragimdjan Abdugafurov, 4Bakhodir
Mukhiddinov
1Senior lecturer of the Tashkent Institute of Chemical Technology, Member of the All-Russian
Mass Spectrometric Society 2Professor of the Tashkent Institute of Chemical Technology 3Professor of the National University of Uzbekistan named after Mirzo Ulugbek 4Professor of the Navoi State Mining and Technology University https://doi.org/10.5281/zenodo.10667029
Abstract. In this research work, the mass spectra of N, N'-hexamethylene-bis-[(m-cresolyl)-carbamate], i.e. MEE-2, were studied. During the fragmentation of bis-carbamate, ions such as m-methylphenyl, hexamethylenediamine, carbamate and others appeared. As a result, ions were identified that proved the elemental composition, molecular weight, chemical bonds, brutto and structural formula of MEE-2 bis-carbamate.
Keywords: bis-carbamate, amine, hexamethylene, fragmentation, spectrum, bond, ions, molecule, atom, structure.
Introduction. Molecules containing the carbamate group play an important role in the development of modern drugs, medicines and chemicals. Carbamate and bis-carbamate derivatives are widely used in agricultural chemicals such as pesticides, fungicides, acaricides and herbicides [1]. They also play an important role in the chemical and paint industries as starting materials, intermediates and solvents [2].
The authors of this article synthesized bis-carbamates of the MEE series. Also, physicochemical, biological and pharmacological parameters were studied and used in various branches of the chemical industry [3-5]. Below is the linear and three-dimensional structure of bis-carbamate MEE-2 (Figure 1):
Figure 1. N,N'-hexamethylene-bis-[(m-cresolyl)-carbamate], i.e. MEE-2
The purpose of this research work is to study the structure of N,N'-hexamethylene-bis-[(m-cresolyl)-carbamate], i.e. MEE-2 with use mass spectroscopic method.
Materials and Methods. Chromato-mass spectrum of N,N'-hexamethylene bis-[(meta-cresolyl)-carbamate] i.e. MEE-2 on an Agilent Technologies 6420 spectrometer, APCI METHOD C118-brand column, 5% phenylmethylsilicone liquid phase, control parameters 500 °C initial temperatures ranging from 150 °C to 320 °C were obtained with an Agilent Technologies 9973 inert mass spectrometer.
Results and Discussions. In the chromato-mass spectrum of N,N'-hexamethylene bis-[(meta-cresolyl)-carbamate] i.e. MEE-2, the formation of ions corresponding to their molecular mass and the mass of fragment ions resulting from their fragmentation was determined (Fig. 2).
Figure 2. Chromato-mass spectrum of N,N'-hexamethylene bis-[(meta-cresolyl)-carbamate]
i.e. MEE-2
In this case, the molecular ion peak of MEE-2 was equal to 383.8. Above is the chromato-mass spectrum of fragment ions formed from the initial MEE-2 molecular ion (Fig. 2). In addition, in the spectrum, mass m/z 249, m/z 135, m/z 91, in the second direction, m/z 234, m/z 100, in the third direction, m/z 293, m/z 249, formation of fragment ions with m/z 202, m/z 158, m/z 114 and m/z 59 was determined.
After the MEE-2 substance was included in the chromato-mass spectrum, a bis-carbamate molecular ion with m/z 383 was formed in 0.711 minutes under the selected conditions. In turn, the MEE-2 ion with m/z 249 from the release of the m/z 135 radical in one direction at 0.183 minutes from the bis-carbamate ion:
C—O II
O
O—C—N
. -VWW-O
II I I II
OH HO
m/z=383
CH3
m/z=135
H3C
O—C-N-O H m/z=249
N H
In the second direction, the MEE-2 ion with m/z 234 splits off at 0.192 minutes with m/z 150 radical:
(OhO-C"N
O H
N-C—O I II HO
CH3
m/z=383
•N— C—O
H O
m/z=150
CH3
H3C
O—C-N O H m/z=234
In the third direction, the separation of MEE-2 ions with m/z 293 from the release of the m-methylphenyl radical at 0.185 minutes was shown:
+
+
H3C
+
+
H3C
H3C-
o
O—C—N II I OH
N-C-I
HO
H3C
CH3
m/z=383
m/z=91
H3C
O—C-N-O H
m/z=293
N-C—O
II
HO
In the chromato-mass spectrum, fragment ions formed from molecular ions also form small ion fragments. The m/z 249 ion formed from MEE-2 separated from itself the hexamethylenediamine radical with m/z 115 to form the ion with m/z 135:
N
H
N-H
H3C
O—C-N-
O H
m/z=115
O — C
H3C
m/z=249 m/z=135
The resulting m/z 135 ion separated from itself a carbon dioxide molecule with m/z 44 and formed an ion with m/z 91:
H3C
O — C O
CO2 m/z=44
m/z=135
HC
m/z=91 J
The ion formed in the second direction of the initial MEE-2 ion separates the m/z 135 radical from it and forms an ion with m/z 100:
O
H3C
O—C-N-O H
H3C
O — C '
O
m/z=135
N" H
m/z=100
m/z=234
The m/z 293 ion formed in the third direction of the molecular ion of MEE-2, in its turn, disintegrates in two directions. In the first direction, m/z 44 separates carbon dioxide and forms an ion with m/z 249:
HC
O—C-N-O H
m/z=293
N-C—O
I
HO
CO2 m/z=44
H3C
O—C-N-OH m/z=249
N H
The second m-methylphenyl radical with m/z 91 is separated from the m/z 249 ion, forming the N,N-hexamethylene bis-carbamate ion with m/z 202:
H3C-
H3C
O—C -N -O H
m/z=293
N—C—O
I
HO
m/z=91
O—C -N -OH
N — C—O
I
HO
m/z=202
+
-n +
+
+
N
H
O
+
+
+
-i +
+
+
+
+
The resulting m/z 202 N,N-hexamethylene bis-carbamate ion separates from itself a m/z 44 carbon dioxide molecule and forms an ion with m/z 158:
O—C-N-O H
N—C—O H O
CO2 m/z=44
O—C-N
OH
m/z=158
m/z=202
The m/z 158 ion also fragmented in two directions. In the first direction, he separated the hexamethyleneamine radical with m/z 99 from itself and formed the carbamate ion with m/z 59:
• N
H
O—C-N
m/z=99
O H
m/z=158
O—C-N
_ O H _ m/z=59
In the second direction, it separated carbon dioxide m/z 44 from itself and formed N,N-hexamethylenediamine ion with m/z 114:
O—C-N-
-N
I
H
O H
m/z=158
CO2 m/z=44
N
H
N I
H
L m/z=114
The above listed fragments of the MEE-2 molecule prove the composition, structure and brutto formula of the synthesized bis-carbamate.
Conclusion. Upon fragmentation of the N,N'-hexamethylene-bis-[(m-cresolyl)-carbamate] molecule, i.e. MEE-2 chromatography-mass spectroscopy method identified ions such as m-methylphenyl, hexamethylenediamine, carbon dioxide, N,N-hexamethylene bis-carbamate, carbamate itself and others. These fragments prove the structure of bis-carbamate MEE-2.
REFERENCES
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—I +
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