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Fragmentation of organophosphorus compounds under electron impact I
The .Science of the Total Environment, 132 (1993) 147-154 Elsevier Science Publishers B.V., Amsterdam
147
Fra nentation of organophosphorus compounds under electron impact I Zaharie Moldovan a, Monica Culea a, Nicolae Palibroda a, Rodica Viorica Muresan b and Olga Musat b
Popescu b,
=Institute of Isotopic and Molecular Technology, R-3400 Cluj-Napoca 5, Romania blnstitute of Chemistry, R-3400 Cluj-Napoca, Romania
ABSTRACT The paper presents mass spectra as well as fragmentation processes under electron impact for the following new compounds with potemial biological activity: (1) S-2-oxobenzoxazolin3-yl methyl diphenylphosphinodithioa~, (2) S-6-chloro-2-oxobenzoxazolin-3-yl methyl diphneylphosphodithioate, (3) S-2-oxobenzoxazolin-3-yl methyl O,O-diphenyl phosphorodithioate, (4) S-6- chloro-2-oxobenzoxazolin-3-yl methyl O,O-diphenyl phosphorodithioate, (5) S-2-oxobenzoxazolin-3-yl diphenyl phosphinothioate. The fragmentation patterns have been determined by exact mass measurements and by metastable transitions. The d,etermination of these substances from dido rent matrices by mass spectrometry methods is discussed.
Key words: mass spectrometry; organophosphorus
INTRODUCTION
There have been many reports of the synthesis and physico-chemical characteristics of organophosphorus compounds as well as of their biological and pharmaceutical properties. Their biological and pharmaceutical activities make possible their use as pesticides and chemiosterility agents in therapeutics [1-3]. The insecticide properties of organophosphorus compounds with a benzoxazolin base is well known [4-12] and new compounds have been obtained by the modification of P-atom substitutes. The structures of the five compounds are shown in Fig. 1. This paper shows the fragmentations mechanisms for these new compounds by E1 and the characteristic ions produced for their structural and quantitative determination in environmem as EI-MS methods are known to be suitable for confirmation of the presence of organophosphorus pesticides [3]. The papers on mass spectrometry of organophosphorus compor~nds 0048-9697/93/$06.00
© 1993 Elsevier Science Publishers B.V. Ali rights reserved
148
z. MOLDOVANET AL.
X
c6 Hsz..> P--S-u
CH2 N
C6HsZ~
0
R
Fig. 1. Structure of the compounds 1-5. (1) Z = - - , X = S, R = H; (2) Z = m , X = S, R = CI; (3) Z = O , X f S , R = H ; (4) Z = O , X = S , R = C I ; (5) Z = - - , X = O , R = H .
indicate a large diversity of reaction processes, in which rearrangement processes are very important, strongly dependent on the types of P radicles present [1,2,13-18]. RESULTS A N D DISCUSSION
The mass spectra of the compounds 1-5 at 70 eV are shown in Table 1. The fragmentation reactions and the structures of the ions are shown in Schemes 1, 2 and 3, respectively. In all cases M+. is an visible ion (4-15%). In Scheme 1 are presented the ions resulting from simple fission of the M+.. The ion a is formed by P-S fission, a common process for compounds with P atoms [12]. The high intensity in compounds 1, 2 and 5 (30%) is due of the extension of the 7r electron system of phenyl radicals to the p orbital of the P atom followed by stabilisation of the positive charge. Detection of the metastable ions and high resolution (exact mass) measurements indicated the elimination from a of the H2Z, C6HsZH and Cell5 groups followed by cyclisation conducting to b, c and, respectively e structures. The cyclisation tendency is a frequent process in the organophosphorus compounds with phenyl substitutes [1,16,17]. The c and e ions lead by a simple fission process to the d ion, a common ion in compounds containing P, S and O atoms [2,15,19]. The ion f is formed from M+. by S-C bond fission and has a relatively low ;.,.,tensity (1-7%). This ion eliminates the neutral C6HsZH, and then S, conducting by a new cyclisation to the structure g and c, respectively. The detection of the metastable transitions confirms the elimination of the XS from f n a very important process in compounds 1 and 2 (25%) - - forming i structures. The i ion consecutively eliminates the neutral H~ and PZ2 leading to the j and k structures, respectively, by a process incorporating ring contraction observed in others organophosphorus compounds [15,201. The ion I, visible only in compounds 3 and 4 (Z = 0)is formed from M+. by fission of the C - N bond. By the elimination of the neutra! SCH2 and C~HsZH the m and a fragment ions are produced r~spectively.
FRAGMENTATION OF ORGANOPHOSPHORUSCOMPOUNDSUNDER ELECTRON IMPACT
149
TABLE l Mass spectral data for compounds 1-5 Mass number and intensity (%)
Ion
M a a° b c c' d e e f f g g' i j k I
397 217 217 -139 139 63 -. 249 217 171 171 185 183 152 263
(6) (30) (2) (2) (24) (15) (4) (0)
m
185
(0)
n
--
o p
q r s t u v w x y z zt z2 z:~
(9) (30) (30)
429 (6) 249 (4) 249 (4) 231 (1) '5 ~ ,., (8) 139 (32) 63 (8) 171 (2)
463 249 249 231 155 139 63 171
(15) (8) (8) (1) (11) (11) (12) (5)
--
281 (1) 249 (4) 187 (6) 187 (6) 217 (5) 215 (0) 152 (3) 295 (1) 201 (1) 320 (22)
281 249 187 187 217 215 152 295. 201 354
(4) (8) (10) (!0) (11) (2) 60) (5) (3) (14)
--
--
110
(3)
110
(4)
140 (13) 218 (100) 107 (8) 180 (1) 136 (2) 109 (4) 148 (16) 120 (1) 104 (6) 77 (41) 134 (1) 78 (9) 135 (4) 91 (2~, 65 (811 51 (17)~ 39 (6)
140 (15) 218 (100) 107 (9) 214 (I) 170 (1) 143 (I) 182 (8) 154 (2) 138 (3) 111 (10) 168 (I) 12 (1) 169 (7) 125 (1) 65 (5) 51 (9) 39 (3)
156 250 123 180 136 109 148 120 104 77 134 78 135 91 65 51 39
(14) (2) (1) (2) (2) (6) (100) (1) (11) (56) (1) (6) (3) (1) (10) (14) (8)
(32) (32) (11) .
431 217 217 -139 139 63 -. 249 217 171 171 185 183 152 263
(7) (31) (31)
(6) (31) (4) (4) (31) (15) (3) (0)
185
(0)
(35) (32) ~i5) .
156 (6) 250 (4) 123 (1) 214 (2) 170 (3) 143 (1) 182 (100) 154 (5) 138 (12) !11 (29) 168 (1) 112 (1) 169 (3) 125 (!) 65 (11) 51 (9) 39 (8)
381 (10) 201 (59) 217 (4) 123 (2) 139 (5) 47 (9) -139 (5) 233 (3) 201 155 (6) 155 (6) 185 (5) 183 (3) 152 (3) 247 (0) 169 (0) ---
124 (2) 202 (100) 107 (1) 180 (1) 136 (2) 109 (5) 148 (13) 120 (3) 104 (5) 77 (58) 134 (1) 78 (11) 135 (3) 91 (2) 65 (8) 51 (29) 39 (5)
Scheme 2 shows the reactions which start with the isomerisation of the molecular ion (involving Z, X and S atoms) or with the rearrangements of M*. by H atom transfer. The first isomerisation process involves the interchange of the X and Z atoms leading to the M' structures, a process obser-
z. MOLDOVAN ETAL
150
~(3,5l--
~=X b +
X SCH2NCO2CBH3R = (CsHBZ)
C~sZH ,~{11
=X
C~.~Z PmX
=
"-
o
c
d
e
cH_X
"I+"
+
"2 M'
~ ~, v-z ~(c,H,z),~.-;
.,,,,,
.
g I
'
x,
~(C,H,Z)2~
.,
*|II
r'r--~
-lII ,
xII
VZ.
,.z,
"*"
Z~ , ' ' ~
~'~;
k
j
4.
~t{3l N CO'~KH"3R - -
{qH5 Z~_S:c
m
~2 --
t
SCH2
O
--
.Ul3l
Scheme 1. Reaction starting by simple fission of M*..
uv
I
Z
X|
-- c6Hsz P-S-Cl - io,% ~- ~R
c~.~x el3l
"I+'I
n
-..i~ >~,-s-c,,-~.-~-- I ~':
O" O
"R I C6~SZPZSC~NC0Z:r~~HsX+
M'
o
,.o
S
S
c~.sz.-,,,-Ex* x -~'--~+ {c~z),~,-x ---.-.r,j.{ ---r,.j.} s
, *.
.. ~ H ¢ \ l
C6~Z/
c'
S
XC.~C0,,."~ "
M"
'+ (C6H-7-iz P
~,~ c~Z>I~.S ,.~sl
o'
XH
XH'I+.
g'
r
P-X- CH2-
M+.__
+
=
e'
i
,,111
I
~ [CBH,~.)z P
*ll)
=
l~,,]"Z
p
"(1)
r
Scheme 2. Reaction starting by isomerisation or by rearrangement of M +..
151
FRAGMENTATION OF ORGANOPHOSPHORUS COMPOUNDS UNDER ELECTRON IMPACT
74-
(csHsz~x
S-
"R *13! s
*z3!
co
CH~ ~ - [ ~
~ a'13)"|C6HsZI2PX s
CH;~o_~
X
"
~H~'P-S-CH2- N ' - ~ [~" -
O"U - "R
M+"
v
t
u
O--V\ R w
R I =**11,3,s ' ) D-c-~.-CH, "~" ~.,." ~'R .t(1,3,~1 x
-] ~.. (C6H5Z)2PXSCH2~ O ~ J ~ " R
2co
=
CsH3RN
y
-3+
Zl
Z l+.
(C6HsZI2PXSCH=
"1."
; LO'~\R '¢ll,3~C0z D . c\n -NH Z2
z3
Scheme 3. Reaction starting by fission o f M +. and charge on heterocyclic side.
vable in similar compounds [2,12,20]. From M' the ion n is formed by a P - X fission and the elimination of C6HsX, a process confirmed by metastable transitions. Ion n, observable only in substances 3 and 4 has a high relative intensity (22 and 14%) and is common for similar compounds [21]. The o is probably produced from the M ' structure being present only in these two substances. A second isomerization process involves the S and X atoms leading to the M" structure. This process is confirmed by m/z's of 139 and 217 for the ions in the mass spectrum of substance 5. The metastable transitions show the formation of the m/z of 139 from that of 227. These data, as TABLE 2 The characteristic ion group for compounds 1-5 m/z
Ion
C o m p o u n d and intensity (%) 1
111
y
139
c/c'
-148 -182 202 218
~ v q q
2
-32
16 -. 100
3
4
5
10
--
29
5
35 --
32 100
11
5
w
--
I00
13 -I00
8 .
. 100
. .
.
.
.
152
z. MOLDOVANET AL
well as high resolution results confirm the isomerisation of M to M", a process observed in organophosphorus compounds with S and O atoms [2,12]. M" by simple fission creates the a' ion (m/z 217) and then by C6H6 elimination the e' ion (m/z 139). No metastable transition confirmed the formatior.~ o f f ' , g' and c' ions. However they cannot be excluded, the m/z 233, |55 and 139 ions being present in compound 5. The q ion is produced by M+. by a five-membered transition state rearrangement process with H transfer from CH2 to X, a common process for organophosphorus compounds [15,18,22,23]. In the compounds 1, 2 and 5 the q ion is the base peak but in 3 and 4 its relative intensity is small (2-4%). This phenomenon is due to the very different electronegativity of the phenoxy and phenyl groups [24]. The q ion eliminates the XH radical (the fragmentation observed in phosphorothioates [2,18]) leading to i ion. Another fragmentation of the q ion is produced by consecutive elimination of the C6HsZH and XH group and the production of the p and r ions. Scheme 3 shows the ions starting by fission of the M+. but with charge localised on heterocyclic fragment, ions with high intensity in organophosphorus compounds [12,15]. Typical for fragmentation of the ions containing heterocyc!ic group are the elimination of the CO, CO2 and HCN common process for benzoxazolinone [25,26] or heterocyclic compounds containing N, O and S atoms [27]. The ion s produced by P-S bond fission eliminates CO2 and HCN successively leading to the t and u structures. The S-C bond dissociation of the M+. produces the v ion base peak in compounds 3 and 4 as well as in other similar compounds [12]. This ion eliminates the neutral CO, CO2 and HCN leading to w, x and y ions. In all cases a weak z ion is observable, being produced from M+. by C - N fission. The elimination of two CO molecules has been reported in early works [25] forming the z~ ion, the fragmentation are not confirmed by metastable transitions. The z2 ion formation is probable from M+. by H migration from CH2 to N and by elimination of CO2 forming z3 structures. The t, x and z3 structures have been reported earlier [25]. EXPERIMENTAL
Synthesis of the compounds The compounds were synthetised at the Institute of Chemistry, ClujNapoca, Romania, by a substitution reaction among the respective thiophosphoroganic salt and a N-Cl-methylbenzoxazoline derivative [4-9]. The purification was made by recrystalisation and verified by thin layer chromatography, elementary analysis and mass spectrometry.
FRAGMENTATION OF ORGANOPHOSPHORUS COMPOUNDS UNDER ELECTRON IMPACT
153
Mass spectrometry conditions
Measurements were performed on a MAT 311 Mass Spectrometer using the following settings: electron energy 70 eV, electron emission 100 ~A and ion source temperature 150°C. Metastable transitions were registered using massanalysed ion kinetic energy spectrometry and high voltage techniques
[281. CONCLUSIONS
Compounds 1-5 can be characterized structurally and quantitatively by the group of six ions shown in Table 2. Th~ base peak for compounds 1, 2 and 5 has a q structure with an m/z of 218 (1 o nd 2) and an m/z 202 (5). For compounds 3 and 4 the base peak has a ~,structure, m/z 148 and 182, respectively. The base ions are adequate for quantitative analysis. For ion y an m/z 111 confirms the presence of Ct atom and ions c and c' (ndz 139) in connection with base ion confirms the structure. REFERENCES l L. AImasi, Les Compos~s Thionophosphororganiques, Masson, Paris, 1976, p. 229. 2 S. Safe and D. Hutzinger, Mass Spectrometry of Pesticides and Pollutants, CRC Press, Cleveland, !976, p. !89. 3 D.G. Durand and D. Barcel6, ConfLrmation of chlorotriazine pesticides, their degradation products and organophosphorus pesticides in soil samples using gas chromatography-mass spectrometry with e!ectron impact and positive- and negative-ion chemical ionization. Anal. Chim. Acta, 243 (1991) 259. 4 W. Lorenz, K. Mannes and G. Schrader (inventors), Farbenfabriken Bayer Aktiengesilschaft (Germany) (assignee), Nouveaux esters thiophosphoriques et proc~d~ pour les preparer, French Patent 1.301.634, 1961. 5 Agripat S.A., Switzerland (assignee), Proc~d6 de preparation d'esters thiophosphoriques et thiophosphoniques hO~rocycliques. French Patent 1.530.204, 1967. 6 M. Sauli (inventor), Rh6ne--Poulenc S.A., France, (assignee), German Patent 2.431.192, 1973. Phosalone, Chem. Abstr., 82 (1975) 170877 b. 7 N.N. Melinkov, Ya.A. Mandidelbaum, G.E. Nikishova and J.N. Nagayuk (inventors), 6-Chloro-2-oxobenzoxazol-3-yl methyl thiophosphoric acid derivatives, USSR Patent 393.283, 1973. 8 J. M~tivier (inventor), Compositions destinies a lutter contre les ectoparesites du betail, French Patent 1.482.025,~ '966. 9 Rh6ne-Poulenc, S.A. France (assignee), Pesticidal heterocyclic esters of thiophosphoric acid, British Patent 1.005.372, 1965. Chem. Abstr., 63 (1965) 18.092 g. 10 J. M~livier (inventor), Soci6t~ des Usines Chimiques Rh6ne-Poulenc, France (assignee), Esters phosphoriques, French Patent 1.277.401, 1960. Chem. Abstr., 57 (1962) 12498 b. II K. Szobo (inventor), Exxon Research and Engineering Co. (assignee), Alkoxyalkyl phosphonates, USA Patent 3.919.359, 1975. Chem. Abstr., 84 (1976) 90.299 r. 12 H.J. Start, B. Abraham, J. Jung, M. Kellert and K. Steihland, Nachweis yon organophosphorinsecficiden durch Gas-Chromatographie-Massenspektrometrie. Fresenius Z. Anal. Chem., 287 (1977) 271.
154
z. M O L D O V A N
El" AL
13 P. Haake and P.S. Ossip, A mass spectrometric study of some dialkylphosphinic acids and their alkyl esters. Tetrahedron, 24 (1968) 565. 14 K. Diemer, P. Haas and W. Kuchen, Bifunktionelle Dithiophosphinsauren und einige ihrer Derivate. Chem. Ber., 111 (1978) 629. 15 Z. Moldovan, N. Palibroda, M. Culea, I. Fenesan and A. Hantz, Electron impact fragmentation of some cyclohexyl thiophosphorogranic amides. Org. Mass Spectrom., 24 (1989) 81. 16 J.H. Beynon, R.A. Saunders and A.E. Williams, The Mass Spectra of Organic Molecules, Elsevier, Amsterdam, 1968, 412p p. 17 R. Popescu, I. Oprean, N. Palibroda and Z. Moldovam, i~tude en spectrom6trie de mass des arylsulfonamides thiophosphororganiques. I. Arylsulfamides de l'acide diphenylthiophinique. Stud. Univ. Babes-Bolyai, Ser. Chem., 34 (1) (1989) 23. 18 Z. Moldovan, M. Culea, N. Palibroda, I. Fenesan and R. Popescu, Electron impact mass spectrometry of phenyl thiophosphoroorganic amides. Org. Mass Spectrom., 26 (1991) 840. 19 R. Popescu, I. Oprean, N. Palibroda and Z. Moldovan, l~tude spectrometrie de mass des arylsulfonamides. Stud. Univ. Babes-Bolyai, Ser. Chem., 33 (i) (1988) 54. 20 R.S. Edmunson, Cyclic organophospshorus compounds. Phosphorus and Sulfur, 9 Part XVI (1981) 307. 21 R.G. Cooks and A.F. Gerrard, Electron impact-induced rearrangements in compounds having the PfS bond. J. Chem. Soc., B (1968) 1327. 22 F.W. McLafferty, Mass spectrometric analysis. Broad applicability to chemical research. Anal. Chem., 23 (1956) 306. 23 D.A. Bafus, E.J. Gallegos and R.W. Kiser, An electron impact investigation of so~.~e alkyl phosphate esters. J. Phys. Chem., 70 (1966) 2614. 24 S.G. Bratsch, A group electronegativity method with Pauling units. J. Che~ Educ., 2 (1985) 101. 25 M.L. Thomson and D.C. De Jongh, Pyrolyses and mass spectra of 2-benzimidazolinone and 2-benzothiazolinone. Can. J. Chem., 51 (1973) 3313. 26 A. Maquestion, Y. Van Haverbeke, C. De Meyer and R. Flammang, lsomerisation du benzoxazole et de l'anthranile sous l'impact electronique. Org. Mass Spectrom.~ 9 (1974) 149. 27 Q.N. Porter and J. Baldas, Mass Spectrometry of Heterocyclic Compounds, WileyInterscience, New York, 1971, p. 288. 28 Z. Moldovan, N. Palibroda, V. Mercea and G. Mihailescu, Kinetic energy release in metastable ions from beta-keto esters. Org. Mass Spectrom. 20 (1985) 77.
147
Fra nentation of organophosphorus compounds under electron impact I Zaharie Moldovan a, Monica Culea a, Nicolae Palibroda a, Rodica Viorica Muresan b and Olga Musat b
Popescu b,
=Institute of Isotopic and Molecular Technology, R-3400 Cluj-Napoca 5, Romania blnstitute of Chemistry, R-3400 Cluj-Napoca, Romania
ABSTRACT The paper presents mass spectra as well as fragmentation processes under electron impact for the following new compounds with potemial biological activity: (1) S-2-oxobenzoxazolin3-yl methyl diphenylphosphinodithioa~, (2) S-6-chloro-2-oxobenzoxazolin-3-yl methyl diphneylphosphodithioate, (3) S-2-oxobenzoxazolin-3-yl methyl O,O-diphenyl phosphorodithioate, (4) S-6- chloro-2-oxobenzoxazolin-3-yl methyl O,O-diphenyl phosphorodithioate, (5) S-2-oxobenzoxazolin-3-yl diphenyl phosphinothioate. The fragmentation patterns have been determined by exact mass measurements and by metastable transitions. The d,etermination of these substances from dido rent matrices by mass spectrometry methods is discussed.
Key words: mass spectrometry; organophosphorus
INTRODUCTION
There have been many reports of the synthesis and physico-chemical characteristics of organophosphorus compounds as well as of their biological and pharmaceutical properties. Their biological and pharmaceutical activities make possible their use as pesticides and chemiosterility agents in therapeutics [1-3]. The insecticide properties of organophosphorus compounds with a benzoxazolin base is well known [4-12] and new compounds have been obtained by the modification of P-atom substitutes. The structures of the five compounds are shown in Fig. 1. This paper shows the fragmentations mechanisms for these new compounds by E1 and the characteristic ions produced for their structural and quantitative determination in environmem as EI-MS methods are known to be suitable for confirmation of the presence of organophosphorus pesticides [3]. The papers on mass spectrometry of organophosphorus compor~nds 0048-9697/93/$06.00
© 1993 Elsevier Science Publishers B.V. Ali rights reserved
148
z. MOLDOVANET AL.
X
c6 Hsz..> P--S-u
CH2 N
C6HsZ~
0
R
Fig. 1. Structure of the compounds 1-5. (1) Z = - - , X = S, R = H; (2) Z = m , X = S, R = CI; (3) Z = O , X f S , R = H ; (4) Z = O , X = S , R = C I ; (5) Z = - - , X = O , R = H .
indicate a large diversity of reaction processes, in which rearrangement processes are very important, strongly dependent on the types of P radicles present [1,2,13-18]. RESULTS A N D DISCUSSION
The mass spectra of the compounds 1-5 at 70 eV are shown in Table 1. The fragmentation reactions and the structures of the ions are shown in Schemes 1, 2 and 3, respectively. In all cases M+. is an visible ion (4-15%). In Scheme 1 are presented the ions resulting from simple fission of the M+.. The ion a is formed by P-S fission, a common process for compounds with P atoms [12]. The high intensity in compounds 1, 2 and 5 (30%) is due of the extension of the 7r electron system of phenyl radicals to the p orbital of the P atom followed by stabilisation of the positive charge. Detection of the metastable ions and high resolution (exact mass) measurements indicated the elimination from a of the H2Z, C6HsZH and Cell5 groups followed by cyclisation conducting to b, c and, respectively e structures. The cyclisation tendency is a frequent process in the organophosphorus compounds with phenyl substitutes [1,16,17]. The c and e ions lead by a simple fission process to the d ion, a common ion in compounds containing P, S and O atoms [2,15,19]. The ion f is formed from M+. by S-C bond fission and has a relatively low ;.,.,tensity (1-7%). This ion eliminates the neutral C6HsZH, and then S, conducting by a new cyclisation to the structure g and c, respectively. The detection of the metastable transitions confirms the elimination of the XS from f n a very important process in compounds 1 and 2 (25%) - - forming i structures. The i ion consecutively eliminates the neutral H~ and PZ2 leading to the j and k structures, respectively, by a process incorporating ring contraction observed in others organophosphorus compounds [15,201. The ion I, visible only in compounds 3 and 4 (Z = 0)is formed from M+. by fission of the C - N bond. By the elimination of the neutra! SCH2 and C~HsZH the m and a fragment ions are produced r~spectively.
FRAGMENTATION OF ORGANOPHOSPHORUSCOMPOUNDSUNDER ELECTRON IMPACT
149
TABLE l Mass spectral data for compounds 1-5 Mass number and intensity (%)
Ion
M a a° b c c' d e e f f g g' i j k I
397 217 217 -139 139 63 -. 249 217 171 171 185 183 152 263
(6) (30) (2) (2) (24) (15) (4) (0)
m
185
(0)
n
--
o p
q r s t u v w x y z zt z2 z:~
(9) (30) (30)
429 (6) 249 (4) 249 (4) 231 (1) '5 ~ ,., (8) 139 (32) 63 (8) 171 (2)
463 249 249 231 155 139 63 171
(15) (8) (8) (1) (11) (11) (12) (5)
--
281 (1) 249 (4) 187 (6) 187 (6) 217 (5) 215 (0) 152 (3) 295 (1) 201 (1) 320 (22)
281 249 187 187 217 215 152 295. 201 354
(4) (8) (10) (!0) (11) (2) 60) (5) (3) (14)
--
--
110
(3)
110
(4)
140 (13) 218 (100) 107 (8) 180 (1) 136 (2) 109 (4) 148 (16) 120 (1) 104 (6) 77 (41) 134 (1) 78 (9) 135 (4) 91 (2~, 65 (811 51 (17)~ 39 (6)
140 (15) 218 (100) 107 (9) 214 (I) 170 (1) 143 (I) 182 (8) 154 (2) 138 (3) 111 (10) 168 (I) 12 (1) 169 (7) 125 (1) 65 (5) 51 (9) 39 (3)
156 250 123 180 136 109 148 120 104 77 134 78 135 91 65 51 39
(14) (2) (1) (2) (2) (6) (100) (1) (11) (56) (1) (6) (3) (1) (10) (14) (8)
(32) (32) (11) .
431 217 217 -139 139 63 -. 249 217 171 171 185 183 152 263
(7) (31) (31)
(6) (31) (4) (4) (31) (15) (3) (0)
185
(0)
(35) (32) ~i5) .
156 (6) 250 (4) 123 (1) 214 (2) 170 (3) 143 (1) 182 (100) 154 (5) 138 (12) !11 (29) 168 (1) 112 (1) 169 (3) 125 (!) 65 (11) 51 (9) 39 (8)
381 (10) 201 (59) 217 (4) 123 (2) 139 (5) 47 (9) -139 (5) 233 (3) 201 155 (6) 155 (6) 185 (5) 183 (3) 152 (3) 247 (0) 169 (0) ---
124 (2) 202 (100) 107 (1) 180 (1) 136 (2) 109 (5) 148 (13) 120 (3) 104 (5) 77 (58) 134 (1) 78 (11) 135 (3) 91 (2) 65 (8) 51 (29) 39 (5)
Scheme 2 shows the reactions which start with the isomerisation of the molecular ion (involving Z, X and S atoms) or with the rearrangements of M*. by H atom transfer. The first isomerisation process involves the interchange of the X and Z atoms leading to the M' structures, a process obser-
z. MOLDOVAN ETAL
150
~(3,5l--
~=X b +
X SCH2NCO2CBH3R = (CsHBZ)
C~sZH ,~{11
=X
C~.~Z PmX
=
"-
o
c
d
e
cH_X
"I+"
+
"2 M'
~ ~, v-z ~(c,H,z),~.-;
.,,,,,
.
g I
'
x,
~(C,H,Z)2~
.,
*|II
r'r--~
-lII ,
xII
VZ.
,.z,
"*"
Z~ , ' ' ~
~'~;
k
j
4.
~t{3l N CO'~KH"3R - -
{qH5 Z~_S:c
m
~2 --
t
SCH2
O
--
.Ul3l
Scheme 1. Reaction starting by simple fission of M*..
uv
I
Z
X|
-- c6Hsz P-S-Cl - io,% ~- ~R
c~.~x el3l
"I+'I
n
-..i~ >~,-s-c,,-~.-~-- I ~':
O" O
"R I C6~SZPZSC~NC0Z:r~~HsX+
M'
o
,.o
S
S
c~.sz.-,,,-Ex* x -~'--~+ {c~z),~,-x ---.-.r,j.{ ---r,.j.} s
, *.
.. ~ H ¢ \ l
C6~Z/
c'
S
XC.~C0,,."~ "
M"
'+ (C6H-7-iz P
~,~ c~Z>I~.S ,.~sl
o'
XH
XH'I+.
g'
r
P-X- CH2-
M+.__
+
=
e'
i
,,111
I
~ [CBH,~.)z P
*ll)
=
l~,,]"Z
p
"(1)
r
Scheme 2. Reaction starting by isomerisation or by rearrangement of M +..
151
FRAGMENTATION OF ORGANOPHOSPHORUS COMPOUNDS UNDER ELECTRON IMPACT
74-
(csHsz~x
S-
"R *13! s
*z3!
co
CH~ ~ - [ ~
~ a'13)"|C6HsZI2PX s
CH;~o_~
X
"
~H~'P-S-CH2- N ' - ~ [~" -
O"U - "R
M+"
v
t
u
O--V\ R w
R I =**11,3,s ' ) D-c-~.-CH, "~" ~.,." ~'R .t(1,3,~1 x
-] ~.. (C6H5Z)2PXSCH2~ O ~ J ~ " R
2co
=
CsH3RN
y
-3+
Zl
Z l+.
(C6HsZI2PXSCH=
"1."
; LO'~\R '¢ll,3~C0z D . c\n -NH Z2
z3
Scheme 3. Reaction starting by fission o f M +. and charge on heterocyclic side.
vable in similar compounds [2,12,20]. From M' the ion n is formed by a P - X fission and the elimination of C6HsX, a process confirmed by metastable transitions. Ion n, observable only in substances 3 and 4 has a high relative intensity (22 and 14%) and is common for similar compounds [21]. The o is probably produced from the M ' structure being present only in these two substances. A second isomerization process involves the S and X atoms leading to the M" structure. This process is confirmed by m/z's of 139 and 217 for the ions in the mass spectrum of substance 5. The metastable transitions show the formation of the m/z of 139 from that of 227. These data, as TABLE 2 The characteristic ion group for compounds 1-5 m/z
Ion
C o m p o u n d and intensity (%) 1
111
y
139
c/c'
-148 -182 202 218
~ v q q
2
-32
16 -. 100
3
4
5
10
--
29
5
35 --
32 100
11
5
w
--
I00
13 -I00
8 .
. 100
. .
.
.
.
152
z. MOLDOVANET AL
well as high resolution results confirm the isomerisation of M to M", a process observed in organophosphorus compounds with S and O atoms [2,12]. M" by simple fission creates the a' ion (m/z 217) and then by C6H6 elimination the e' ion (m/z 139). No metastable transition confirmed the formatior.~ o f f ' , g' and c' ions. However they cannot be excluded, the m/z 233, |55 and 139 ions being present in compound 5. The q ion is produced by M+. by a five-membered transition state rearrangement process with H transfer from CH2 to X, a common process for organophosphorus compounds [15,18,22,23]. In the compounds 1, 2 and 5 the q ion is the base peak but in 3 and 4 its relative intensity is small (2-4%). This phenomenon is due to the very different electronegativity of the phenoxy and phenyl groups [24]. The q ion eliminates the XH radical (the fragmentation observed in phosphorothioates [2,18]) leading to i ion. Another fragmentation of the q ion is produced by consecutive elimination of the C6HsZH and XH group and the production of the p and r ions. Scheme 3 shows the ions starting by fission of the M+. but with charge localised on heterocyclic fragment, ions with high intensity in organophosphorus compounds [12,15]. Typical for fragmentation of the ions containing heterocyc!ic group are the elimination of the CO, CO2 and HCN common process for benzoxazolinone [25,26] or heterocyclic compounds containing N, O and S atoms [27]. The ion s produced by P-S bond fission eliminates CO2 and HCN successively leading to the t and u structures. The S-C bond dissociation of the M+. produces the v ion base peak in compounds 3 and 4 as well as in other similar compounds [12]. This ion eliminates the neutral CO, CO2 and HCN leading to w, x and y ions. In all cases a weak z ion is observable, being produced from M+. by C - N fission. The elimination of two CO molecules has been reported in early works [25] forming the z~ ion, the fragmentation are not confirmed by metastable transitions. The z2 ion formation is probable from M+. by H migration from CH2 to N and by elimination of CO2 forming z3 structures. The t, x and z3 structures have been reported earlier [25]. EXPERIMENTAL
Synthesis of the compounds The compounds were synthetised at the Institute of Chemistry, ClujNapoca, Romania, by a substitution reaction among the respective thiophosphoroganic salt and a N-Cl-methylbenzoxazoline derivative [4-9]. The purification was made by recrystalisation and verified by thin layer chromatography, elementary analysis and mass spectrometry.
FRAGMENTATION OF ORGANOPHOSPHORUS COMPOUNDS UNDER ELECTRON IMPACT
153
Mass spectrometry conditions
Measurements were performed on a MAT 311 Mass Spectrometer using the following settings: electron energy 70 eV, electron emission 100 ~A and ion source temperature 150°C. Metastable transitions were registered using massanalysed ion kinetic energy spectrometry and high voltage techniques
[281. CONCLUSIONS
Compounds 1-5 can be characterized structurally and quantitatively by the group of six ions shown in Table 2. Th~ base peak for compounds 1, 2 and 5 has a q structure with an m/z of 218 (1 o nd 2) and an m/z 202 (5). For compounds 3 and 4 the base peak has a ~,structure, m/z 148 and 182, respectively. The base ions are adequate for quantitative analysis. For ion y an m/z 111 confirms the presence of Ct atom and ions c and c' (ndz 139) in connection with base ion confirms the structure. REFERENCES l L. AImasi, Les Compos~s Thionophosphororganiques, Masson, Paris, 1976, p. 229. 2 S. Safe and D. Hutzinger, Mass Spectrometry of Pesticides and Pollutants, CRC Press, Cleveland, !976, p. !89. 3 D.G. Durand and D. Barcel6, ConfLrmation of chlorotriazine pesticides, their degradation products and organophosphorus pesticides in soil samples using gas chromatography-mass spectrometry with e!ectron impact and positive- and negative-ion chemical ionization. Anal. Chim. Acta, 243 (1991) 259. 4 W. Lorenz, K. Mannes and G. Schrader (inventors), Farbenfabriken Bayer Aktiengesilschaft (Germany) (assignee), Nouveaux esters thiophosphoriques et proc~d~ pour les preparer, French Patent 1.301.634, 1961. 5 Agripat S.A., Switzerland (assignee), Proc~d6 de preparation d'esters thiophosphoriques et thiophosphoniques hO~rocycliques. French Patent 1.530.204, 1967. 6 M. Sauli (inventor), Rh6ne--Poulenc S.A., France, (assignee), German Patent 2.431.192, 1973. Phosalone, Chem. Abstr., 82 (1975) 170877 b. 7 N.N. Melinkov, Ya.A. Mandidelbaum, G.E. Nikishova and J.N. Nagayuk (inventors), 6-Chloro-2-oxobenzoxazol-3-yl methyl thiophosphoric acid derivatives, USSR Patent 393.283, 1973. 8 J. M~tivier (inventor), Compositions destinies a lutter contre les ectoparesites du betail, French Patent 1.482.025,~ '966. 9 Rh6ne-Poulenc, S.A. France (assignee), Pesticidal heterocyclic esters of thiophosphoric acid, British Patent 1.005.372, 1965. Chem. Abstr., 63 (1965) 18.092 g. 10 J. M~livier (inventor), Soci6t~ des Usines Chimiques Rh6ne-Poulenc, France (assignee), Esters phosphoriques, French Patent 1.277.401, 1960. Chem. Abstr., 57 (1962) 12498 b. II K. Szobo (inventor), Exxon Research and Engineering Co. (assignee), Alkoxyalkyl phosphonates, USA Patent 3.919.359, 1975. Chem. Abstr., 84 (1976) 90.299 r. 12 H.J. Start, B. Abraham, J. Jung, M. Kellert and K. Steihland, Nachweis yon organophosphorinsecficiden durch Gas-Chromatographie-Massenspektrometrie. Fresenius Z. Anal. Chem., 287 (1977) 271.
154
z. M O L D O V A N
El" AL
13 P. Haake and P.S. Ossip, A mass spectrometric study of some dialkylphosphinic acids and their alkyl esters. Tetrahedron, 24 (1968) 565. 14 K. Diemer, P. Haas and W. Kuchen, Bifunktionelle Dithiophosphinsauren und einige ihrer Derivate. Chem. Ber., 111 (1978) 629. 15 Z. Moldovan, N. Palibroda, M. Culea, I. Fenesan and A. Hantz, Electron impact fragmentation of some cyclohexyl thiophosphorogranic amides. Org. Mass Spectrom., 24 (1989) 81. 16 J.H. Beynon, R.A. Saunders and A.E. Williams, The Mass Spectra of Organic Molecules, Elsevier, Amsterdam, 1968, 412p p. 17 R. Popescu, I. Oprean, N. Palibroda and Z. Moldovam, i~tude en spectrom6trie de mass des arylsulfonamides thiophosphororganiques. I. Arylsulfamides de l'acide diphenylthiophinique. Stud. Univ. Babes-Bolyai, Ser. Chem., 34 (1) (1989) 23. 18 Z. Moldovan, M. Culea, N. Palibroda, I. Fenesan and R. Popescu, Electron impact mass spectrometry of phenyl thiophosphoroorganic amides. Org. Mass Spectrom., 26 (1991) 840. 19 R. Popescu, I. Oprean, N. Palibroda and Z. Moldovan, l~tude spectrometrie de mass des arylsulfonamides. Stud. Univ. Babes-Bolyai, Ser. Chem., 33 (i) (1988) 54. 20 R.S. Edmunson, Cyclic organophospshorus compounds. Phosphorus and Sulfur, 9 Part XVI (1981) 307. 21 R.G. Cooks and A.F. Gerrard, Electron impact-induced rearrangements in compounds having the PfS bond. J. Chem. Soc., B (1968) 1327. 22 F.W. McLafferty, Mass spectrometric analysis. Broad applicability to chemical research. Anal. Chem., 23 (1956) 306. 23 D.A. Bafus, E.J. Gallegos and R.W. Kiser, An electron impact investigation of so~.~e alkyl phosphate esters. J. Phys. Chem., 70 (1966) 2614. 24 S.G. Bratsch, A group electronegativity method with Pauling units. J. Che~ Educ., 2 (1985) 101. 25 M.L. Thomson and D.C. De Jongh, Pyrolyses and mass spectra of 2-benzimidazolinone and 2-benzothiazolinone. Can. J. Chem., 51 (1973) 3313. 26 A. Maquestion, Y. Van Haverbeke, C. De Meyer and R. Flammang, lsomerisation du benzoxazole et de l'anthranile sous l'impact electronique. Org. Mass Spectrom.~ 9 (1974) 149. 27 Q.N. Porter and J. Baldas, Mass Spectrometry of Heterocyclic Compounds, WileyInterscience, New York, 1971, p. 288. 28 Z. Moldovan, N. Palibroda, V. Mercea and G. Mihailescu, Kinetic energy release in metastable ions from beta-keto esters. Org. Mass Spectrom. 20 (1985) 77.