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Composition of vanadylporphyrins obtained from West Surgut petroleum
Petrol. Chem. U.S.S.R. Vol. 23p No. 3j pp. 168-172, 1983 Printed in Poland
0031-45458183 $10.00 + .00 9 1985 Pergamon Press Ltd.
COMPOSITION OF VANADYLPORPHYRINS OBTAINED F R O M WEST SURGUTPETROLEUM* T. K. MOZZHELINA,O. V. SEREBRENNIKOVA,A. M. SHUL'GAand V. I. TITOV , Institute of Petroleum Chemistry, U.S.S.R. Academyof Sciences
(Received 10 August 1981) PREVIOUSim,~estigation has shown [1] that PMR spectroscopy may provide information about.the structural features of petroleum porphyrins. In this study ipdividual p0rp!lyr!n, fractions from chromatographic separation of a demetallized concentrate of vanadylp0rphyrin petroleum (well 160) of West Surgut deposits, were examined. The concentrate obtained was demetallized using concentrated sulphuric acid. The demetallized concentrate was eluted by chloroform from cohmms (40/100 tim) containing silica gel. Electron spectra ("Specord" spectrophotometer) and low-resolution mass-spectra (MAT-311 "Varian" mass-spectrometer) were obtained. Mass-spectra were recorded at 70 eV from samples evaporated at 225~ PMR spectra of the porphyrins Were obtained using a 100 MHz JEOL-100 spectrometer at 25~ Chromatographic (silica gel) separation of the demetallized concentrate gave five coloured bands of porphyrins, four of these were red and eluted stepwise with chlorofor m . The fifth band (brown) was strongly retained by silica gel; it could only be eluted from the column by 5 ~o methyl alcohol chloroform. All five fractions were collected separately and purified by elution from activity IV alumina. Figure 1 (la to 5a) shows electron spectra of the fractions obtained. Spectra are shown irf the ordei', in which fractions were eluted from the silica gel column. Porphyrins Of all the fractions obtained have four typical absorption bands in the range of,500, to 620 nm. The first two fractions have a typical etio-spectrum, i.e..absorption band intensity decreases stepwise.with increasing wavelength. The 3rd, 4th and 5th fractions ate characterized by so-called DPEP type spectrum, which normally cOrresponds with the presence of porphyrin with an isocyclic ring. However, the spectrum o f t h e 5th" fraction differs in the position of its absorption bands from the spectra of 3rd and 4th fractions these bands were displaced toward the red range. MS analysis of fractions shows that in the 1st and 2nd fractions the principal porphyrins, i.e. M series alkyl-substituted of etioporphyrins. The molar mass distributibh(Fig. 1, lb-:4b) shows the presence in the lateral alkyl chains of tliege compounds some 7 to 18 carbon atoms; the 3rd and 4th fractions are characterized by the predominance of M2 desoxyphylloerythroetioporphyrins with masses corresponding to 9 to 18 carbon atoms in lateral alkyl chains. As the polarity of fractions increases, * Neftekhimiya 23, No. 4, 562-566, 1983.
168
Composition of vanadylporphyrins the average molar mass of porphyrins o f each series present decreases (Table). When the 1st fraction contains compounds with a molar mass up to 576, then in the 4th fraction the molar mass of porphyrins does not exceed 518 (Fig. 1). The low volatility o f the 5th fraction precluded a clear record o f the porphyrins present. ib
]iI1, !1"i,i ijil
500
GOD
' ' ' ~53q ' - 552 4 22 q50q78 505
500
600
q22 450 q78 506 834 562
3h
500
GO0
I !1
OZ2 1150#78 50S 5Jq 562
Z/b
I
,I[
[jzl',,, 500
600
500
GOD ~2,nrn
q22 qSOq78 5Q8 53q #lolar maas .
Flo. 1. Characteristics of petroleum porphyrin fractions, a: Absorption spectra; b: mass-spectra continuous lines- M series; broken lines- M-2 series. CIIARACTEILISTICS OF PETROLEUM PORPItYRIN FRACTIONS
No. of fraction
Type of electron spectrum
Etio DPEP * MS data. t Data of PMR sl~r
Amount of porphyrins, % M series*
M series t
87 71 lO 13
90
75 6 I1
CH~/CzHs t
Molecules containing one free fl-position, %
1"7 2"5 1"7 2"4
70 20 15 40
Molar mass* M series
M-2 series
475 457 439 435
500 497 467 460
T.K, MOZZIIF_.LINA el a[.
170 "
0091
8/7 8t5 8.J5
636
IJ3
6.55 6.57
C 6~5 647
FIo. 2. PMR spectra of petroleum porphyrln fractions obtained in CDCI~. a: Fraction No. 4; b: fraction No. I; c: fraction No. 5.
Compositionof vanadylporphyrins
I~i
MS analysis of the first four fractions shows satisfactory agreement with analytical result of these fractions using PMR spectroscopy; these data indicate that in the 1st and 2nd fractions the mairt structural groups are the alkylporphyrins (structure a), the 3rd and 4th fraction being mainly represented by porphyrins containing an isocyclic ring (structure b).
Porphyrin structures: R~
R~
t t I ~ I I G .
R2~ RI
P'4
R5
Rs~ R7 R
118 (2'
.
2
RI
~ I
b
R
R6
t34
3
R7 R
R5
~
2
~ta
~
Nr
I
0
a-etio-type (M series); b-desoxyphylloerythroetio-type (M-2 series); c-oxidized forms (M-2 series, oxy). PMR spectroscopy shows CHs groups to be the main fl-substituents of the porphyrin ring (overlapping signals with z 6.35 to 6"55 p.p.m.) although C2Hsgroups (typical quartet (z 6.04 p.p.m, and triplet z 8-16 p.p.m.) are also seeh. The relative content of methyl and ethyl substituents varies in particular fractions (Table). The relative number of ethyl substituents decreases from the 1st to the 2nd and from the 3rd to the 4th fractions, and appears to correspond with the observed reduction in average molar mass of the porphyrins seen in transition from the 1st to the 2nd and from the 3rd to the 4th fractions. Porphyrins showing pyrrole with rings with vacant fl-positions are present in practically all fractions. A signal with z I'1 p.p.lm. (Fig. 2) corresponds to CH-protons in fl-position in the PMR spectrum. The proportion of porphyrins with these free positions differs in the same way as the proportion of methyl and ethyl substituents, differs for individual fractions (Table). The presence of free fl-positions in porphyrin fractions, having anisocyclic ring is significant, since the method previously used [2] for determining the presence of free positions in petroleum porphyrins hinders the analysis of isoeyclic compounds due to the breakdown of such structures under experimental conditions. Accordingly this investigation suggests that petroleum desoxyphylloerythroetioporphyrins, as well as alkylporphyrins, include compounds 9with free fl-positions in the py.rrole rings. Unfortunately, MS could not be used for the study of the composition of 5th high polarity fraction. However, electron and PMR spectroscopy permitted certain conclusions to be drawn about the structure of porphyrin compounds in this frac-
T. K. b,fozz.~uNA et al. ti0n. The electron spectrum of the 5th fraction is of DPEP type, carrying an isocyclic ring. The bathochrome shift of absorption bands and the polarity of this fraction suggests the presence of polar groups in the porphyrins, however the IR spectrum indicates that they are not carboxyl groups. The P M R spectra of the 5th fraction porphyrins indicates the possible presence of structures, similar to a recently synthesized porphyrin which carries an OH group in position 10 in its isocyclic ring (structure c) [3]. Signal from a CH2-group at position 10 is absent from the P M R spectrum (Fig. 2). Signal but a proton at position 10 is observed in the xyeak field (r 2.9 p.p.m.). This strong shift most be due to the proximity of an electronegative group. The structure proposed is also supported by the shift of four NH-protgns ' (in CFaCOOH) to the weak field, compared with the position of signals of desoxyphylloerythroetioporphyrin type. In this work signals from NH protons are observed in CFaCOOH with z 13.3; 14.0; 14"9; 15.45 p.p.m. For fractions which are mainly porphyrins containing an isocycli c ring and for synthetic desoxyphylloerythroetioporphyrin these signals are observed with z 13"6; 14.35; 15-1 and 15.7 p.p.m. The structure ~'e propose explains the polarity of the 5th fraction, the bathochrome shift of absorption bands in the electron spectrum as well as the absence of C = O vibrations from the IR spectrum. Thus the isocyclic ring is assumed [3] to have been oxidized at position 10 to hydroxyl during passage of the porphyrins over silica gel. However, further study is required to determine whether there are similar structures in petroleum and if not, at what stage of porphyrin separation such hydroxylated porphyrins are formed. SUMMARY
1. Mass-spectr0metry, electron and PMR spectroscopy were used to examine tile compositio'rt of individual chromatographic petroleum fr/~ctions of vana'd~,loorphyrins from West Surgut petroleum. 2. It was found that mixtures of petroleum porphyrins contain compounds incorporating art isocyclic ring as well as compounds with unsubstituted p-positions in the pyrrole rings. The presence of a hydroxyl group in position 10 is a distirictive structural element of porphyrins of high polarity. REFERENCES
1. A. 1M. SHU].,'GA, T. K. MOZZHELINA, O. V. SEREBRENNIKOVA and "V. I. TITOV, lqeftekkimiya 20, 273, 1980 2. V. R; ANTIPENKO, G. S. PEVNEVA, G. V. KIRILLOVA and V. I. TITOV, Ncf!ckhimiya 19, 278, 1979 3. G.V. PONOMAREV, A. M. SHUL'GA and u P. SUBOCH, Tez. dokl.Vses, konf. po fizicheskoi i koordinatsionnoi khimii porikinov, p. 18, Ivan0vo, 1979
0031-45458183 $10.00 + .00 9 1985 Pergamon Press Ltd.
COMPOSITION OF VANADYLPORPHYRINS OBTAINED F R O M WEST SURGUTPETROLEUM* T. K. MOZZHELINA,O. V. SEREBRENNIKOVA,A. M. SHUL'GAand V. I. TITOV , Institute of Petroleum Chemistry, U.S.S.R. Academyof Sciences
(Received 10 August 1981) PREVIOUSim,~estigation has shown [1] that PMR spectroscopy may provide information about.the structural features of petroleum porphyrins. In this study ipdividual p0rp!lyr!n, fractions from chromatographic separation of a demetallized concentrate of vanadylp0rphyrin petroleum (well 160) of West Surgut deposits, were examined. The concentrate obtained was demetallized using concentrated sulphuric acid. The demetallized concentrate was eluted by chloroform from cohmms (40/100 tim) containing silica gel. Electron spectra ("Specord" spectrophotometer) and low-resolution mass-spectra (MAT-311 "Varian" mass-spectrometer) were obtained. Mass-spectra were recorded at 70 eV from samples evaporated at 225~ PMR spectra of the porphyrins Were obtained using a 100 MHz JEOL-100 spectrometer at 25~ Chromatographic (silica gel) separation of the demetallized concentrate gave five coloured bands of porphyrins, four of these were red and eluted stepwise with chlorofor m . The fifth band (brown) was strongly retained by silica gel; it could only be eluted from the column by 5 ~o methyl alcohol chloroform. All five fractions were collected separately and purified by elution from activity IV alumina. Figure 1 (la to 5a) shows electron spectra of the fractions obtained. Spectra are shown irf the ordei', in which fractions were eluted from the silica gel column. Porphyrins Of all the fractions obtained have four typical absorption bands in the range of,500, to 620 nm. The first two fractions have a typical etio-spectrum, i.e..absorption band intensity decreases stepwise.with increasing wavelength. The 3rd, 4th and 5th fractions ate characterized by so-called DPEP type spectrum, which normally cOrresponds with the presence of porphyrin with an isocyclic ring. However, the spectrum o f t h e 5th" fraction differs in the position of its absorption bands from the spectra of 3rd and 4th fractions these bands were displaced toward the red range. MS analysis of fractions shows that in the 1st and 2nd fractions the principal porphyrins, i.e. M series alkyl-substituted of etioporphyrins. The molar mass distributibh(Fig. 1, lb-:4b) shows the presence in the lateral alkyl chains of tliege compounds some 7 to 18 carbon atoms; the 3rd and 4th fractions are characterized by the predominance of M2 desoxyphylloerythroetioporphyrins with masses corresponding to 9 to 18 carbon atoms in lateral alkyl chains. As the polarity of fractions increases, * Neftekhimiya 23, No. 4, 562-566, 1983.
168
Composition of vanadylporphyrins the average molar mass of porphyrins o f each series present decreases (Table). When the 1st fraction contains compounds with a molar mass up to 576, then in the 4th fraction the molar mass of porphyrins does not exceed 518 (Fig. 1). The low volatility o f the 5th fraction precluded a clear record o f the porphyrins present. ib
]iI1, !1"i,i ijil
500
GOD
' ' ' ~53q ' - 552 4 22 q50q78 505
500
600
q22 450 q78 506 834 562
3h
500
GO0
I !1
OZ2 1150#78 50S 5Jq 562
Z/b
I
,I[
[jzl',,, 500
600
500
GOD ~2,nrn
q22 qSOq78 5Q8 53q #lolar maas .
Flo. 1. Characteristics of petroleum porphyrin fractions, a: Absorption spectra; b: mass-spectra continuous lines- M series; broken lines- M-2 series. CIIARACTEILISTICS OF PETROLEUM PORPItYRIN FRACTIONS
No. of fraction
Type of electron spectrum
Etio DPEP * MS data. t Data of PMR sl~r
Amount of porphyrins, % M series*
M series t
87 71 lO 13
90
75 6 I1
CH~/CzHs t
Molecules containing one free fl-position, %
1"7 2"5 1"7 2"4
70 20 15 40
Molar mass* M series
M-2 series
475 457 439 435
500 497 467 460
T.K, MOZZIIF_.LINA el a[.
170 "
0091
8/7 8t5 8.J5
636
IJ3
6.55 6.57
C 6~5 647
FIo. 2. PMR spectra of petroleum porphyrln fractions obtained in CDCI~. a: Fraction No. 4; b: fraction No. I; c: fraction No. 5.
Compositionof vanadylporphyrins
I~i
MS analysis of the first four fractions shows satisfactory agreement with analytical result of these fractions using PMR spectroscopy; these data indicate that in the 1st and 2nd fractions the mairt structural groups are the alkylporphyrins (structure a), the 3rd and 4th fraction being mainly represented by porphyrins containing an isocyclic ring (structure b).
Porphyrin structures: R~
R~
t t I ~ I I G .
R2~ RI
P'4
R5
Rs~ R7 R
118 (2'
.
2
RI
~ I
b
R
R6
t34
3
R7 R
R5
~
2
~ta
~
Nr
I
0
a-etio-type (M series); b-desoxyphylloerythroetio-type (M-2 series); c-oxidized forms (M-2 series, oxy). PMR spectroscopy shows CHs groups to be the main fl-substituents of the porphyrin ring (overlapping signals with z 6.35 to 6"55 p.p.m.) although C2Hsgroups (typical quartet (z 6.04 p.p.m, and triplet z 8-16 p.p.m.) are also seeh. The relative content of methyl and ethyl substituents varies in particular fractions (Table). The relative number of ethyl substituents decreases from the 1st to the 2nd and from the 3rd to the 4th fractions, and appears to correspond with the observed reduction in average molar mass of the porphyrins seen in transition from the 1st to the 2nd and from the 3rd to the 4th fractions. Porphyrins showing pyrrole with rings with vacant fl-positions are present in practically all fractions. A signal with z I'1 p.p.lm. (Fig. 2) corresponds to CH-protons in fl-position in the PMR spectrum. The proportion of porphyrins with these free positions differs in the same way as the proportion of methyl and ethyl substituents, differs for individual fractions (Table). The presence of free fl-positions in porphyrin fractions, having anisocyclic ring is significant, since the method previously used [2] for determining the presence of free positions in petroleum porphyrins hinders the analysis of isoeyclic compounds due to the breakdown of such structures under experimental conditions. Accordingly this investigation suggests that petroleum desoxyphylloerythroetioporphyrins, as well as alkylporphyrins, include compounds 9with free fl-positions in the py.rrole rings. Unfortunately, MS could not be used for the study of the composition of 5th high polarity fraction. However, electron and PMR spectroscopy permitted certain conclusions to be drawn about the structure of porphyrin compounds in this frac-
T. K. b,fozz.~uNA et al. ti0n. The electron spectrum of the 5th fraction is of DPEP type, carrying an isocyclic ring. The bathochrome shift of absorption bands and the polarity of this fraction suggests the presence of polar groups in the porphyrins, however the IR spectrum indicates that they are not carboxyl groups. The P M R spectra of the 5th fraction porphyrins indicates the possible presence of structures, similar to a recently synthesized porphyrin which carries an OH group in position 10 in its isocyclic ring (structure c) [3]. Signal from a CH2-group at position 10 is absent from the P M R spectrum (Fig. 2). Signal but a proton at position 10 is observed in the xyeak field (r 2.9 p.p.m.). This strong shift most be due to the proximity of an electronegative group. The structure proposed is also supported by the shift of four NH-protgns ' (in CFaCOOH) to the weak field, compared with the position of signals of desoxyphylloerythroetioporphyrin type. In this work signals from NH protons are observed in CFaCOOH with z 13.3; 14.0; 14"9; 15.45 p.p.m. For fractions which are mainly porphyrins containing an isocycli c ring and for synthetic desoxyphylloerythroetioporphyrin these signals are observed with z 13"6; 14.35; 15-1 and 15.7 p.p.m. The structure ~'e propose explains the polarity of the 5th fraction, the bathochrome shift of absorption bands in the electron spectrum as well as the absence of C = O vibrations from the IR spectrum. Thus the isocyclic ring is assumed [3] to have been oxidized at position 10 to hydroxyl during passage of the porphyrins over silica gel. However, further study is required to determine whether there are similar structures in petroleum and if not, at what stage of porphyrin separation such hydroxylated porphyrins are formed. SUMMARY
1. Mass-spectr0metry, electron and PMR spectroscopy were used to examine tile compositio'rt of individual chromatographic petroleum fr/~ctions of vana'd~,loorphyrins from West Surgut petroleum. 2. It was found that mixtures of petroleum porphyrins contain compounds incorporating art isocyclic ring as well as compounds with unsubstituted p-positions in the pyrrole rings. The presence of a hydroxyl group in position 10 is a distirictive structural element of porphyrins of high polarity. REFERENCES
1. A. 1M. SHU].,'GA, T. K. MOZZHELINA, O. V. SEREBRENNIKOVA and "V. I. TITOV, lqeftekkimiya 20, 273, 1980 2. V. R; ANTIPENKO, G. S. PEVNEVA, G. V. KIRILLOVA and V. I. TITOV, Ncf!ckhimiya 19, 278, 1979 3. G.V. PONOMAREV, A. M. SHUL'GA and u P. SUBOCH, Tez. dokl.Vses, konf. po fizicheskoi i koordinatsionnoi khimii porikinov, p. 18, Ivan0vo, 1979