Supporting information
Mass Spectrometric Study of the Gas-Phase DifluorocarbeneExpulsion of Polyfluorophenyl Cations via F-Atom Migration
Hao-Yang Wang,*1 Ying Gao,1 Fang Zhang,1Chong-Tian Yu,2 Chu Xu,1Yin-Long Guo*1
1Shanghai Mass Spectrometry Center, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
2Agilent Technologies (China) Co., Ltd. 140 Tianlin Road, Shanghai 200233, China
- Experimental section
- Chemicals and materials
- GC-MS(/MS) conditions in GC-Q-TOF MS
- ESI-MS(/MS) conditions in ESI-TSQ MS
- Theoretical computation methods
- Figures, Tables and Schemes
- References
- Experimental section
- Chemicals and materials
Compounds 1,2,4-trifluorobenzene (98%), 2,6-difluoroiodobenzene (97%), 2,6-difluoronitrobenzene (98%) were purchased from Adamas-beta Chemical Reagent Co. Ltd. (Shanghai, China). 2,5-difluoroiodobenzene (98%)and perfluoroiodobenzene (95%) were purchased from TCI Chemical Reagent Co. Ltd. (Tokyo, Japan). 3,5-difluoroiodobenzene (98%) was purchased from Alfa aesar Chemical Reagent Co. Ltd. (Ward Hill, MA, USA). 2,3,4-Trifluoroiodobenzenewas purchased from Fluorochem Chemical Reagent Co. Ltd. (Derbyshire, UK). Acetonitrile and methanolwere purchased from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China) and were dehydrated before use.
1.2.GC-MS(/MS) conditions in GC-Q-TOF MS
GC-MS(/MS) measurements were performed with a 7200 accurate-mass GC-Q-TOF MS instrument (Agilent Technologies, Santa Clara, USA), using a fused silica DB-35MS capillary column of 30 m × 0.25 mm i.d. The injector was operated at 250°C in split mode (split ratio of 1:50) and helium (purity>99.99%) was used as the carrier gas at 1.2 mL/min. The GC oven temperature was programmed from an initial temperature of 50°C, ramped at 10°C /min to 220°C, resulting in a total run time of 17 min. The retention time of these compounds: 1,2,4-trifluorobenzene at 2.04 min, 3,5-difluoroiodobenzene at 5.73 min, perfluoroiodobenzene at 5.96 min, 2,3,4-Trifluoroiodobenzene at 6.85 min, 2,5-difluoroiodobenzene at 6.93 min, 2,6-difluoronitrobenzene at 7.21 min, 2,6-difluoroiodobenzene at 7.45 min. CH3OH solutions of samples were prepared in concentration of 2 µg/ml and the injection volume was 1 μL. The other optimized parameters included a transfer line temperature of 300°C and an ion source of 250°C. TOF for MS was operated at 5.0 spectra/s acquiring the mass range m/z35–500 and resolutionabout 13,500 (FWHM). The MS2 conditions were fixed for each compound with a quadrupole for isolation of precursor ion at a medium MS resolution and a linear hexapole collision cell with nitrogen at 1.5 mL/min as the collision gas. Perfluorotributylamine (PFTBA) was utilized for daily MS calibration. MassHunter Acquisition B.06 and MassHunter Qualitative Analysis B.05 were applied for the control of the equipment, and the acquisition and treatment of data. The collision energy (Laboratory) applied for all the ions was 20 eV.
1.3.ESI-MS(/MS) conditions in ESI-TSQ MS
The ESI-MS/MS experiments were performedon a Finnigan TSQ Quantum Access™ triple-quadrupolemass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA)equipped with a standard ESI ion source. Nitrogen was used asthe sheath and auxiliary gases, whereas argon was used as the collision gas.The basic ESI conditionswere as follows: vacuum, 2.8×10–6 Torr; sprayvoltage, 4500 V; mass range m/z35–500 capillary temperature, 270°C; sheath gaspressure, 20 arbitrary units; and auxiliary gas pressure, 5 arbitraryunits. The collision energy was dependent onthe dissociation capability of the precursor ions. Data acquisitionand analysis were carried out with the Xcalibur softwarepackage (Version 2.0, Thermo Fisher Scientific).CH3CN solutions of samples were prepared in concentration of 2 µg/ml and the injection speed of 5 μL/min was used for all of the ESI-MS(/MS) experiments. At this condition, the CH3CN of 2,6-difluoroiodobenzene and perfluoroiodobenzene gave their radical cations at m/z 240 and 294, at collision energy (Laboratory) 30 eV, respectively. The further ESI-MS/MS of 4 at m/z 294 and5 at m/z 167 were performed from the in-source decay of radical cations at m/z 240 and 294, respectively.
1.4.Theoretical computation methods
All of the computational calculations were carried out with the Gaussian03 suite of programs[1]. The B3LYP method[2] was used for geometry optimizations and single point energy calculations. The 6-31G(d) basis set[3, 4] was used for the C, H and F atoms. All of the gas phase minima and transition structures, which have also been referred to as transition states, were characterized by frequency analysis. Frequency calculations were used to identify the minimum structures with all of the real frequencies, whereas the transition states were calculated with only one imaginary frequency. Zero point energy (ZPE)[5] corrections were applied at the same level.
- Figure, Tables and Schemes
Figure S1. EI-MS spectra from GC-Q-TOF MS of: (a) 2,5-difluoroiodobenzene, (b) 2,3,4-trifluoroiodobenzene, (c) 1,2,4-trifluorobenzene. The ions marked with“#”were product ions from the ions marked with “*”by loss of CF2 (50 amu.).
Figure S2. EI-MS/MS spectra from GC-Q-TOF MS of: (a)ion at m/z 258 (radical cation of 2,3,4-trifluoroiodobenzene), (b) ion at m/z 131 (Collision ELaboratory=20eV, stuctrues shown in Figure).The ions marked with“#” were product ions from the ions marked with “*”by loss of CF2 (50 amu.).
Figure S3. ESI-MS/MS spectra from ESI-TSQ-MS of: (a)1at m/z 240 (radical cation of 2,6-difluoroiodobenzene), (b) 2at m/z 113, (c) 7 at m/z 294 (radical cation ofperfluoroiodobenzene), (d) 8 at m/z 167 (Collision ELaboratory= ~30eV). The ions marked with“ #”were product ions from the ions marked with “*”by loss of CF2 (50 amu.).
Figure S4. EI-MS/MS spectra from GC-Q-TOF MS of ion5at m/z129 from 2,6-difluoronitrobenzene. The ion6at m/z 101 was the major fragment ion by loss of CO and ion at m/z 109 was the fragment ion by loss of HF. The proposed fragmentation pathways of ion5at m/z129 were listed below.
Figure S5.The optimized structures and relative energies of 6a-6dat the DFT/B3LYP/6-31G(d) level of theory, which indicated that 6b in singlet state with fluorine atoms on 1, 3 carbons was most stable species. Thus when 6a has enough extra energy, it might rearrange to its thermodynamicallyfavorable isomer 6b.
Table S1. Comparison of the results of accurate mass determinations by GC-Q-TOF MS and the actual masses for the main product ions of compounds.
Compounds / Elemental composition of ions / m/z detected / theoretical m/z / relative error (ppm)C6H3F2I•+ / 239.9254 / 239.9247 / 5.0
2,6-Difluoroiodobenzene / C6H3F2+ / 113.0194 / 113.0197 / -2.5
C5H3+ / 63.0228 / 63.0229 / -2.6
C6H2F3I•+ / 257.9141 / 257.9153 / 2.6
2,3,4-Trifluoroiodobenzene / C6H2F3+ / 131.0104 / 131.0103 / -0.7
C5H2F+ / 81.0132 / 81.0135 / 3.8
C6F5I•+ / 293.8971 / 293.8965 / -4.0
Pentafluoroiodobenzene / C6F5+ / 166.9906 / 166.9915 / 5.2
C5F3+ / 116.9937 / 116.9947 / 8.2
Table S2. EI-MS spectra data of several ployfluoroiodobenzenesand pentafluorophenyl isothiocyanate. The ions marked with“#”(product ions) and“*” (parent ions) were ion pairs to dissociate CF2. The data marked with “a” were obtained from our mass spectrometric measurements and the rest data were summarized from NIST web book [6].
Names / Structures / m/z (abundance in %)2,4-Difluoroiodobenzene / / 63#(43.8),113*(46.0),240(100)
3,5-Difluoroiodobenzene / / 63#(16.9),113*(49.3),240(100) a
2,5-Difluoroiodobenzene / / 63#(17.4),113*(38.1),240(100)a
2,6-Difluoroiodobenzene / / 63#(18.5),113*(39.2),240(100) a
2,3,4-Trifluoroiodobenzene / / 81#(25.6),131*(28.1), 256(100)a
Pentafluoroiodobenzene / / 117#(44.3),167*(36.3),294(100) a
Pentafluorophenyl isothiocyanate / / 31(48.0), 58(5.2), 63(17.2), 71(29.2), 93(29.9), 117# (51.1), 167*(11.1), 193(39), 225(100)
Table S3. EI-MS spectra data of several ployfluoronitrobenzenespolyfluorobenzenes and difluorobenzonitriles. The ions marked with “#”(product ions) and “*”(parent ions) were ions paris to dissociate CF2.The data marked with “a” were obtained from our mass spectrometric measurements and the rest data were summarized from NIST web book [6].
Names / Structures / m/z (abundance in %)3,4-Difluoronitrobenzene / / 30(41.5),63#(100),101(26.7),113*(85.4),129(23.7),159(64.8)
2,4-Difluoronitrobenzene / / 30(78.1),63#(100),101(62.6),113*(59.1),129(60.3),159(71.6)
2,6-Difluoronitrobenzene / / 63#(58.6), 75(21.6), 101(81.0),113*(49.3),129(82.4),159(100)a
2,5-Difluoronitrobenzene / / 30(27.8),63#(80.7),101(52.0),113*(100),129(10.4),159(92.7)
1,2-Difluorobenzene / / 50(4.5),57(5.7),63(13.4),88(14.2),114(100)
1,3-Difluorobenzene / / 50(7.8),57(8.3),63(20.8),88(12.9),114(100)a
1,4-Difluorobenzene / / 50(12.9),57(15.0),63(35.5),88(16.2),114(100)
1,2,4-Trifluoroiodobenzene / / 63#(11.2), 81(16.5), 112(7.3), 113*(3.4), 132(100)a
Hexafluorobenzene / / 31(12.0),69(3.9), 117# (49.6), 136(9.4), 155(15.4), 167* (13.4), 186(100)
2,5-Difluorobenzonitrile / / 31(11.1),75(6.2),88(12.5),112(20.1),139(100)
2,6-Difluorobenzonitrile / / 31(12.7),75(8.9),88(13.8),112(20.2),139(100)
Notes: the fragment ion at m/z 63 of difluorobenzenes in ESI-MS might formed directly by loss of radical ·CF2H. We even observed the fragment ions of CF3+ at m/z 69 in EI-MS specrum of hexafluorobenzenevia the F-atom migration.
Table S4. EI-MS spectra data of several difluoroanilines, difluorophenols, and 2,4-difluoroanisole. No obvious product ions formed by loss of CF2 were observed in the EI-MS spectra of these compounds in this table.
Names / Structures / m/z values of ions (abundance in %)3,4-Difluoroaniline / / 101(35.1),102(35.6),129(100)
2,6-Difluoroaniline / / 82(28.8),101(21.5),102(13.5),109(28.2),129(100)
2,4-Difluoroaniline / / 82(21.1),101(34.6),102(30.8),109(13.5),129(100)
2,5-Difluoroaniline / / 82(23.4),101(28.9),102(21.1),109(8.8),129(100)
2,3-Difluorophenol / / 82(35.1),101(20.5), 102(7.7), 130(100)
3,4-Difluorophenol / / 82(16.3),101(80.3), 102(49.4), 130(100)
2,6-Difluorophenol / / 82(61.7),101(8.1),110(29.5),130(100)
2,4-Difluorophenol / / 82(83.4),101(23.4),110(12.3),130(100)
3,5-Difluorophenol / / 82(20.1),101(53.6), 102(49.0), 110(0.9),130(100)
2,5-Difluorophenol / / 63(25.7),82(91.4),101(28.8),110(3.9),130(100)
2,4-Difluoroanisole / / 101(75.3),129(89.8),144(100)
Table S5. EI-MS spectra data of several polyfluorohalogenbenzenes (X=Cl and Br), and polyfluorocarbonylbbenzene derivates. The ions marked with“#”(product ions) and“*”(parent ions) were ion pairs to dissociate CF2.
Names / Structures / m/z (abundance in %)1-Chloro-2,3,5,6-tetrafluorobenzene / / 99#(20.0),149*(24.4),184(100), 186(isotopic peak, 56.2)
1-Bromo-2,3,5,6-tetrafluorobenzene / / 99#(46.7),149*(64.1),228(100), 230 (isotopic peak, 98.4)
1-Bromo-2,3,4,6-tetrafluorobenzene / / 99#(100),149*(44.1),228(61.3) 230 (isotopic peak, 56.2)
2,3,6-Trifluoroacetophenone / / 43(46.1),81#(28.4),131*(40.8),159(100),174(32.0)
2,4,6-Trifluorobenzoyl chloride / / 81#(35.6),131*(40.9),159(100), 194(8.2), 196(isotopic peak, 2.8)
2',4'-Difluoroacetophenone / / 43(11.1), 63#(12.6),113*(31.5),141(100), 156(14.3)
1-(2,6-Difluorophenyl)ethan-1-one / / 43(16.7), 63#(12.0),113*(22.2),141(100), 156(13.6)
3,5-Difluoroacetophenone / / 15(22.6), 43(74.3),63#(41.4),113*(89.0), 141(100),156(35.1)
2,3-Difluoroacetophenone / / 15(12.2), 43(47.6),63#(28.6),113*(50.7), 141(100),156(27.3)
Pentafluoroacetophenone / / 15(6.6), 43(56.0),117#(27.7),167*(39.4),195(100),210(32.2)
Table S6. EI-MS spectra data of several pesticides containing F atoms and Cl atoms in aromatics. The data of pentachloronitrobenzene and pentafluoronitrobenzene was obtained from NIST web book, the data of Etoxazole was obtained from NIST/EPA/NIH Mass Spectral Database (NIST 11).[6]The ions marked with“#”(product ions) and “*” (parent ions) were ion pairs to dissociate CF2. The ions marked with “@” (product ion) and “$”(parent ion) were ion pair to dissociate CCl2 (ions in [] were isotopic peaks group).
Names / Structures / m/zvalues of major fragment ions (abundance in %)Pentachloronitrobenzene / / 30 (54.6), 107(27.1),[142 (50.1), 144(33.4)], [165 (7.6), 167(7.8)]@, [177(27.4), 179(26.0)],[212(45.3), 214(61.8), 216(30.4)], [235(60.5), 237(100), 239(65.3)],[ 247(42.2), 249(70.8), 251(45.3), 253(14.0)]$,[263(26.3), 265(42.5), 267(27.0), 269(9.3)], [293(50.4), 295(83.5), 297(51.5), 299(16.1)]
Pentafluoronitrobenzene / / 30 (100), 117#(73.0), 155 (21.2), 167*(34.4), 183(27.0), 213(53.9)
Etoxazole / / 41(11.7), 57(27.8), 63#(5.4), 77(14.2), 91(25.9), 107(11.2), 113*(11.1), 115(19.6), 117(13.2), 129(16.3), 131(12.1), 133(11.2), 141(100)……161(33.5), 175(24.8), 176 (33.1), 187(49.7), 204(73.3), 300(52.5), 302(29.0), 330(35.6), 344(15.3), 359(29.5)
Scheme S1. Summarizing the substitution group effects on CF2dissociation process of polyfluorophenyl compounds.
Scheme S2. The possible fragmentation pathways for difluorophenyl compounds with substitute groups, such as: -OCH3, -OH, -CN and –NH2, which did notoccurred the expulsion CF2 as major pathways.
- References
- Gaussian 03, Revision D.01,Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Montgomery, Jr., J.A., Vreven, T., Kudin, K.N., Burant, J.C., Millam, J.M., Iyengar, S.S., Tomasi, J., Barone, V., Mennucci, B., Cossi, M., Scalmani, G., Rega, N., Petersson, G.A., Nakatsuji, H., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa, J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Klene, M., Li, X., Knox, J.E., Hratchian, H.P., Cross, J.B., Bakken, V., Adamo, C., Jaramillo, J., Gomperts, R., Stratmann, R.E., Yazyev, O., Austin, A.J., Cammi, R., Pomelli, C., Ochterski, J.W., Ayala, P.Y., Morokuma, K., Voth, G.A., Salvador, P., Dannenberg, J.J., Zakrzewski, V.G., Dapprich, S., Daniels, A.D., Strain, M.C., Farkas, O., Malick, D.K., Rabuck, A.D., Raghavachari, K., Foresman, J.B., Ortiz, J.V., Cui, Q., Baboul, A.G., Clifford, S., Cioslowski, J., Stefanov, B.B., Liu, G., Liashenko, A., Piskorz, P., Komaromi, I., Martin, R.L., Fox, D.J., Keith, T., Al-Laham, M.A., Peng, C.Y., Nanayakkara, A., Challacombe, M., Gill, P.M.W.,Johnson, B., Chen, W., Wong, M.W., Gonzalez, C., and Pople, J.A. Gaussian, Inc., Wallingford CT, 2004.
- Becke,A.D.:Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys.98, 5648–5652 (1993).
- Ditchfield, R., Hehre,W.J., Pople, J.A.: Self-consistent molecular-orbital methods. IX. an extended Gaussian-type basis for molecular-orbital studies of organic molecules. J. Chem.Phys.54, 724–728 (1971)
- Hehre, W.J.,Ditchfield, R., Pople, J.A.: Self-consistent molecular orbital methods. XII. Further extensions of Gaussian-type basis sets for use in molecular orbital studies of organic molecules. J. Chem. Phys.56, 2257–2261(1972)
- Scott, A.P., Radom, L.:Harmonic vibrational frequencies: an evaluation of Hartree−Fock, Møller−Plesset, quadratic configuration interaction, density functional theory, and semiempirical scale factors. J. Phys. Chem.100, 16502–16513(1996)
- (a) Stein,S.E.:"Mass Spectra"in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, Linstrom P.J., Mallard,W.G. (Eds.)National Institute of Standards and Technology, Gaithersburg MD, 20899, (retrieved May 27, 2013).(b) Stein,S. E. NIST/EPA/NIH Mass Spectral Database (NIST 11) and NIST Mass Spectral Search Program (Version 2.0g). May 19, 2011.
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