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Hydrocarbon composition of extracts obtained from petroleum fractions by extractive crystallization with thiourea
HYDROCARBON COMPOSITION OF EXTRACTS OBTAINED FROM PETROLEUM FRACTIONS BY EXTRACTIVE CRYSTALLIZATION WITH THIOUREA* yw. I. BAGRII, P. I. SA~I~, N. S. VORO~'~VA and AT,. A. PETROV A. V. Topchiev Institute of Petrochemical Synthesis, U.S.S.R. Academy of Sciences Institute of Geology and Processing of Mineral Fuels
(Received 26 December 1966)
THE large number of cross-linked and structural isomers considerably hindered the investigation of cyclic paraffin petroleum hydrocarbons. Of 234 hydrocarbons identified in petroleum in connection with problem No. 6 of the American Petroleum Institute during the period of 1927-1964 only 36 were eyclopentane and cyelohexane derivatives [1]. Methylcyeloheptane, 12 bicycle-paraffins and one tricyelie hydrocarbon were also found. Data on the presence in petroleum of the first bieyclio cyelohexane hydrocarbon, trans-bieyclo [4.4.0]-decane (trans-deealin) were only published in 1953 [2] and the hydrocarbon containing two condensed eyelopentane rings of cis-bieyelo [3.3.0] octane (cis-pentalane) was first detected in 1958 [3]. Hydrocarbons containing bridge bonds occupy a special place among polycyclic naphthene hydrocarbons. Similar hydrocarbons, which contain cyclohexane rings in the molecule, cannot dehydrogenate to form aromatic hydrocarbons without rupture of C--C bonds. Their investigation in petroleum was therefore even more difficult. Up to 1963 only two such hydrocarbons present in petroleum were known. Tricycle [3.3.1.13'7] decane was found in petroleum by Landa and Machacek in 1933 [4] and bicycle [3.2.1] octane was identified in 1958 [3]. The use of modern methods of separation--thermodiffusion, preparative and capillary gas-liquid chromatography and spectroscopic methods of investigation (IR, NMR, mass-spectroscopy) now make it possible to study more intensively the structure of saturated cyclic petroleum hydrocarbons. Thus, Lindeman and Le Tourneau recently identified in Californian petroleum several new bicyclie bridge hydrocarbons, namely bicycle [2.2.1] heptane, a few isomeric methylbicyclo [2.2.1] heptanes and bicycle [2.2.2] octane. Landa published data on the identification in petroleum of monomethyladamantanes [6]. Adamantane was also found in petroleum of the Romashkin [7] and Baku deposits [8]. * Neftekhimiya 7, No. 4, 515-518, 1967. 159
160
YE. I. BAGRII et
al.
I t has been p o i n t e d o u t in a previous r e p o r t [8] t h a t , for t h e qualitative d e t e r m i n a t i o n o f certain bridge h y d r o c a r b o n s in petroleums, e x t r a c t s can be used which can easily be o b t a i n e d f r o m p e t r o l e u m fractions b y r e p e a t e d extractive crystallization w i t h thiourea. T h e purpose o f this investigation was t o d e t e r m i n e i f it is possible to use t h e m e t h o d of e x t r a c t i v e crystallization with t h i o u r e a to separate bicyclie h y d r o c a r b o n c o n c e n t r a t e s f r o m p e t r o l e u m fractions which can t h e n be f u r t h e r analysed. A gasoline f r a c t i o n o f p e t r o l e u m was t r e a t e d several times with t h i o u r e a a n d m e t h a n o l using a ratio of h y d r o c a r b o n s : t h i o u r e a : m e t h a n o l of 2 : 1 : 1. F r e s h t h i o u r e a was a d d e d t o t h e filtrate o b t a i n e d f r o m the previous e x p e r i m e n t . T h e e x t r a c t s o b t a i n e d were joined a n d s u b j e c t e d to f u r t h e r t r e a t m e n t with t h i o u r e a EL
[
~
mV
I
II" I
min 130
I
,.,A,ot li'
I
I
I
100
1
1
I
50
b
2 5
19 _ ~
17
" 1
14 15 13
t
rain 150
11 I
100
9
3
67
10 I
I
I
50
0
Chromatogram of extract II of petroleum obtained from the lqadkirmakin sand strata of the Balakhansk deposit: a--capillary column of 75 m length, 0.25 mm diameter, stationary phase squalane, inlet pressure of carrier gas--helium 1.55 arm, temperature 80°C; b--capillary column of 70 m length, 0.25 mm diameter, stationary phase tetrachlorodibutyl phthalate, inlet pressure of helium 1-3 arm, temperature 80°C. The numbers of peaks correspond to the numbers of hydrocarbons in the Table.
Hydrocarbon composition of extracts from petroleum fractions
161
and methanol with a ratio of hydrocarbons : thiourea : methanol of 7 : 1 : 1. E x t r a c t I I was obtained. Parts of the chromatograms of extract II, which correspond to the retention time of Cs-C9 hydrocarbons, are shown in Fig. a,b. The hydrocarbons were identified in extract I I by gas-liquid chromatography. Hydrocarbons found in the extracts are tabulated. C9 bridge hydrocarbons (Table, Nos. 5, 6, 10, 11, 14, 15, 16, 18, 20) were identified by comparing their relative retention volumes with the data of previous studies [9, 10]. Hydrocarbons were also identified by adding a C9 hydrocarbon mixture obtained by isomerization of 2-methyl-cis-bicyclo [3.3.0] octane with A1Br3 [11]. The presence of 8-methylbieyclo [3.2.1] octane (Table, No. 13) was confirmed by the addition of a hydrocarbon mixture* enriched with this isomer and by comparing relative retention volumes [12]. 2-methyl-cis-bicyclo [3.3.0] octane, cis and trans-bicyclo [4.3.0] nonanes and bicyclo [3.3.1] nonane were identified by addition of reference hydrocarbons. The presence of 1-methyl-, endo- and exo-3-methyl-cis-bieyelo [3.3.0] octanes was confirmed by comparing their relative retention volumes with the data of a previous study [13]. Production of extracts. From 900 g petroleum of the Nadkirmakinsk sand strata of the Balakhan deposit [8] 60 g (6.05 wt, %) distillate was distilled into a column having an efficiency of 15 theoretical plates in the temperature range of 70 to 180°C (n~° 1.4326, p~0 0.7822). The fraction was agitated for 2 hr with 30 g thiourea and 35 ml methanol at 18 to 20°C. The adduct was decomposed, as described in a previous paper [8], and 3.8 g of extract I obtained. 5 ml methanol was added to the filtrate and continuously agitated for 2 hr with 30 g thiourea at 18 to 20°C. Similar operations were repeated six times; all extracts I were combined. The yield of extracts ranged from 5.2 g in the second experiment to 0.7 g in the sixth. The overall amount of extract I was 18.6 g (31.0 wt.% calculated as initial distillate, n~° 1.4449, p~0 0.7992). 18 g extract I was stirred for 2 hr with 2.5 g thiourea and 3 ml methanol at 18 to 20°C. After decomposition of the adduct 0.63 g of extract II was obtained (1.05 wt. ~o calculated as the initial gasoline fraction). To identify the hydrocarbons by capillary gas-liquid chromatography two columns were used which contained different stationary liquid phases-squalane and dibutyl-tetrachlorophthalate. The variation of relative retention volumes of certain cyclic hydrocarbons during separation in a polar phase provided additional means for correct identification. Thus, if endo-3-methylcis-bicyclo [3.3.0] octane is retained with squalane more strongly than 1-methyl bicyclo [2.2.2] octane, an inverse relationship is observed on dibutyltetrachlorophthalate. A reduction in relative retention volume (from 200.4 to 194.5) in a polar phase is also observed for 2-methylbicyclo [2.2.2] octane. * The mixture was provided b y N. A. Belikova.
162
YE.
I . B A G R I I et al.
HYDROCARBONS ISOLATED FROM A 7 0 - 1 8 0 ° PETROLEUM FRACTION OF THE B A L ~ K H A N S ~ r DEPOSIT BY EXTRACTIVE CRYSTALLIZATIOl~ W I T H THIOUREA (EXTRACT I I )
Relative retention volume at 80 ° on No.
1 2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 20
Hydrocarbon
c/s-Bicyclo [3.3.0] octane Bicyclo [3.2.1] octane Bicyclo [2.2.2] octane 1-Methyl-c/s-bicyclo [3.3.0] octane 1-Methylbicyclo [3.2.1] octane 1-Methylbicyclo [2.2.2] octane endo-3-Methyl-cis-bicyclo [3.3.0] octane exo.2-Methyl-cis-bicyclo [3.3.0] octane exo-3-Methyl-cis-bieyclo [3.3.0] octane exo-3-Methylbieyclo [3.2.1] octane exo-6-Methylbicyclo [3.2.1] octane endo-2-Methyl-cis-bicyclo [3.3.0] octane 8-Methylbicyclo [3.2.1] octane endo-2-Methylbicyclo [3.2.1] octane 2-Methylbieyclo [2.2.2] octane endo-6-Methylbicyclo [3.2.1] octane trans-Bicyclo [4.3.0] nonane exo-2.Methylbicyclo [3.2.1] octane cis-Bicyclo [4.3.0] nonane Bicyclo [3.3.1] nonane and (or) bicyclo [3.2.2] nonane
Relative content (°/o) in the extract calculated from a chromatogram on dibutyltetrasqualane chlorophthalate
squalane
dibutyltetrachlorophthalate
100.0 110.1 114.9
100.0 108.8 111.5
15.6 12.4 1.7
16.2 12.4 2.0
125.3 139.5 150.1
124.0 139-6 149.$
5.6 9.7 3.6
6"1 9.5 2.4
152"5
145"4
4.1
2.3
154"9
153.1
7.6
8.9
163.1
158.2
4.5
3.3
170.6
164.7
1.6
2.0
178.5
175.1
2.6
2-5
193'0 193.7
189.7 189'7
1.8 1.9
2.5
196.5 200.4
198.5 194.5
3.6 2.0
3.9 2.9
209.2 213.6
202.0 224.7
2.6 3.0
0.5 6.7
216.5 274.6
214.5 272.8
1.5 9.1
1.4 9"4
312.0
302.0
5.5
5.1
A n i n c r e a s e i n t h e c o n t e n t o f endo-6-methylbicyclo [3.2.1] o c t a n e ( T a b l e , N o . 16) d u r i n g s e p a r a t i o n i n s q u a l a n e , o f trans-bicyclo [4.3.0] n o n a n e ( T a b l e , N o . 17) i n d i b u t y l t e t r a c h l o r o p h t h a l a t e a n d s o m e o t h e r h y d r o c a r b o n s ( T a b l e ) p r o v e s t h a t i n s e p a r a b l e i m p u r i t i e s a r e p r e s e n t i n t h e s e cases. F o r m o s t h y d r o c a r b o n s t h e d i f f e r e n c e o f c o n t e n t i n e x t r a c t s I I is n e g l i g i b l e w h e n t h e chromatograms are calculated for different phases. A quantitative calcula-
Hydrocarbon eomposltion of extraets from petroleum fractions
163
tion of ehromatograms was carried out using a system of internal standards. I n those few eases w h e n t h e s e p a r a t i o n of p e a k s was n o t clear (e.g. p e a k No. 10, F i g u r e a) a v a l u e equal to 0.75 of t h e height of t h e p e a k was a s s u m e d in the calculation. T h e a u t h o r s are grateful t o A. F. P l a t e a n d N. A. Belikova, w h o k i n d l y p r o v i d e d bieyelo [3.2.2] n o n a n e a n d exo-8-methylbicyclo [3.2.1] o c t a n e specimens. Ye. I. A m o s o v a t o o k p a r t in t h e e x p e r i m e n t a l p a r t o f t h e s t u d y . SUMMARY
I. Repeated extractive crystallization with thiourea can be used for rapid qualitative determination of methylsubstituted bicyclic C9 saturated hydroc a r b o n s in gasoline p e t r o l e u m fractions. 2. I n a gasoline f r a c t i o n of p e t r o l e u m from t h e N a d k i r m a k i n s k s a n d s t r a t a o f t h e B a l a k h i n deposit t w e n t y C8-C 9 bieyclic h y d r o c a r b o n s were found. More t h a n half o f t h e h y d r o c a r b o n s identified were n a p h t h e n i e h y d r o c a r b o n s
which contain bridge bonds. Translated by E. SEY~RE REFERENCES ]. M. BE~FI~RIDGE, Oil and Gas J. 62, No. 37, 130, 1964
2. F. D. ROSSINI, B. Dzh. Meir and A. Dzh. STREIF, Uglevodorody nefti (Petroleum Hydrocarbons) (Translated from English). Izd. inostr, lit., Leningrad, 1957 3. B. J. MAIR, P. E. EBERLY, N. C. Jr. KROUSKOP and F. D. ROSSINI, Analyt. Chem. 30, No. 3, 393, 1958 4. S. IANDA and V. MACHACEK, Coll. Czeehosl. Chem. Communs 5, 1, 1933 5. L.P. LINDEMAN, and R. L. Le TOURNEAU, Proe. Sixth World Petrol. Congress sect. V, Paper 14, Frankfurt, 1963 6. L. LANDA, Curl Sei. 32, No. 11,485, 1963 7. S. GALA, M. KURASH and S. LANDA, Neftekhimiya 6, No. 1, 3, 1966 8. Ye. I. BAGRII, Ye. I. AMOSOVA and P. L SANIN, Neftekhimiya 6, No. 5, 665, 1966 9. A. F. PLATE, N. A. BELIKOVA, A. A. BOBYLEVA, N. I. GUSAR' and S. V. VITT, Dokl. AN SSSR 163, No. 4, 902, 1965 10. N. A. BELIKOVA, N. I. GUSAR' I. Ye. SOSNINA, M. B. TUROVA-POLYAK and A. F. PLATE, Neftekhimiya 6, No. 2, 179, 1966 11. N. S. VOROB'EVA and Al. A. PETROV, Neftekhimiya 5, No. 6, 801, 1965 12. N. A. BELIKOVA, A. A. BOBYLEVA and A. F. PLATE, Zh. organ, khimii, 3 No. 3, 515, 1967 13. J. KNOTNERUS and A. F. BICKEL, Rec. tray. chim. Pays-Bas 83, No. 4, 400, 1964
(Received 26 December 1966)
THE large number of cross-linked and structural isomers considerably hindered the investigation of cyclic paraffin petroleum hydrocarbons. Of 234 hydrocarbons identified in petroleum in connection with problem No. 6 of the American Petroleum Institute during the period of 1927-1964 only 36 were eyclopentane and cyelohexane derivatives [1]. Methylcyeloheptane, 12 bicycle-paraffins and one tricyelie hydrocarbon were also found. Data on the presence in petroleum of the first bieyclio cyelohexane hydrocarbon, trans-bieyclo [4.4.0]-decane (trans-deealin) were only published in 1953 [2] and the hydrocarbon containing two condensed eyelopentane rings of cis-bieyelo [3.3.0] octane (cis-pentalane) was first detected in 1958 [3]. Hydrocarbons containing bridge bonds occupy a special place among polycyclic naphthene hydrocarbons. Similar hydrocarbons, which contain cyclohexane rings in the molecule, cannot dehydrogenate to form aromatic hydrocarbons without rupture of C--C bonds. Their investigation in petroleum was therefore even more difficult. Up to 1963 only two such hydrocarbons present in petroleum were known. Tricycle [3.3.1.13'7] decane was found in petroleum by Landa and Machacek in 1933 [4] and bicycle [3.2.1] octane was identified in 1958 [3]. The use of modern methods of separation--thermodiffusion, preparative and capillary gas-liquid chromatography and spectroscopic methods of investigation (IR, NMR, mass-spectroscopy) now make it possible to study more intensively the structure of saturated cyclic petroleum hydrocarbons. Thus, Lindeman and Le Tourneau recently identified in Californian petroleum several new bicyclie bridge hydrocarbons, namely bicycle [2.2.1] heptane, a few isomeric methylbicyclo [2.2.1] heptanes and bicycle [2.2.2] octane. Landa published data on the identification in petroleum of monomethyladamantanes [6]. Adamantane was also found in petroleum of the Romashkin [7] and Baku deposits [8]. * Neftekhimiya 7, No. 4, 515-518, 1967. 159
160
YE. I. BAGRII et
al.
I t has been p o i n t e d o u t in a previous r e p o r t [8] t h a t , for t h e qualitative d e t e r m i n a t i o n o f certain bridge h y d r o c a r b o n s in petroleums, e x t r a c t s can be used which can easily be o b t a i n e d f r o m p e t r o l e u m fractions b y r e p e a t e d extractive crystallization w i t h thiourea. T h e purpose o f this investigation was t o d e t e r m i n e i f it is possible to use t h e m e t h o d of e x t r a c t i v e crystallization with t h i o u r e a to separate bicyclie h y d r o c a r b o n c o n c e n t r a t e s f r o m p e t r o l e u m fractions which can t h e n be f u r t h e r analysed. A gasoline f r a c t i o n o f p e t r o l e u m was t r e a t e d several times with t h i o u r e a a n d m e t h a n o l using a ratio of h y d r o c a r b o n s : t h i o u r e a : m e t h a n o l of 2 : 1 : 1. F r e s h t h i o u r e a was a d d e d t o t h e filtrate o b t a i n e d f r o m the previous e x p e r i m e n t . T h e e x t r a c t s o b t a i n e d were joined a n d s u b j e c t e d to f u r t h e r t r e a t m e n t with t h i o u r e a EL
[
~
mV
I
II" I
min 130
I
,.,A,ot li'
I
I
I
100
1
1
I
50
b
2 5
19 _ ~
17
" 1
14 15 13
t
rain 150
11 I
100
9
3
67
10 I
I
I
50
0
Chromatogram of extract II of petroleum obtained from the lqadkirmakin sand strata of the Balakhansk deposit: a--capillary column of 75 m length, 0.25 mm diameter, stationary phase squalane, inlet pressure of carrier gas--helium 1.55 arm, temperature 80°C; b--capillary column of 70 m length, 0.25 mm diameter, stationary phase tetrachlorodibutyl phthalate, inlet pressure of helium 1-3 arm, temperature 80°C. The numbers of peaks correspond to the numbers of hydrocarbons in the Table.
Hydrocarbon composition of extracts from petroleum fractions
161
and methanol with a ratio of hydrocarbons : thiourea : methanol of 7 : 1 : 1. E x t r a c t I I was obtained. Parts of the chromatograms of extract II, which correspond to the retention time of Cs-C9 hydrocarbons, are shown in Fig. a,b. The hydrocarbons were identified in extract I I by gas-liquid chromatography. Hydrocarbons found in the extracts are tabulated. C9 bridge hydrocarbons (Table, Nos. 5, 6, 10, 11, 14, 15, 16, 18, 20) were identified by comparing their relative retention volumes with the data of previous studies [9, 10]. Hydrocarbons were also identified by adding a C9 hydrocarbon mixture obtained by isomerization of 2-methyl-cis-bicyclo [3.3.0] octane with A1Br3 [11]. The presence of 8-methylbieyclo [3.2.1] octane (Table, No. 13) was confirmed by the addition of a hydrocarbon mixture* enriched with this isomer and by comparing relative retention volumes [12]. 2-methyl-cis-bicyclo [3.3.0] octane, cis and trans-bicyclo [4.3.0] nonanes and bicyclo [3.3.1] nonane were identified by addition of reference hydrocarbons. The presence of 1-methyl-, endo- and exo-3-methyl-cis-bieyelo [3.3.0] octanes was confirmed by comparing their relative retention volumes with the data of a previous study [13]. Production of extracts. From 900 g petroleum of the Nadkirmakinsk sand strata of the Balakhan deposit [8] 60 g (6.05 wt, %) distillate was distilled into a column having an efficiency of 15 theoretical plates in the temperature range of 70 to 180°C (n~° 1.4326, p~0 0.7822). The fraction was agitated for 2 hr with 30 g thiourea and 35 ml methanol at 18 to 20°C. The adduct was decomposed, as described in a previous paper [8], and 3.8 g of extract I obtained. 5 ml methanol was added to the filtrate and continuously agitated for 2 hr with 30 g thiourea at 18 to 20°C. Similar operations were repeated six times; all extracts I were combined. The yield of extracts ranged from 5.2 g in the second experiment to 0.7 g in the sixth. The overall amount of extract I was 18.6 g (31.0 wt.% calculated as initial distillate, n~° 1.4449, p~0 0.7992). 18 g extract I was stirred for 2 hr with 2.5 g thiourea and 3 ml methanol at 18 to 20°C. After decomposition of the adduct 0.63 g of extract II was obtained (1.05 wt. ~o calculated as the initial gasoline fraction). To identify the hydrocarbons by capillary gas-liquid chromatography two columns were used which contained different stationary liquid phases-squalane and dibutyl-tetrachlorophthalate. The variation of relative retention volumes of certain cyclic hydrocarbons during separation in a polar phase provided additional means for correct identification. Thus, if endo-3-methylcis-bicyclo [3.3.0] octane is retained with squalane more strongly than 1-methyl bicyclo [2.2.2] octane, an inverse relationship is observed on dibutyltetrachlorophthalate. A reduction in relative retention volume (from 200.4 to 194.5) in a polar phase is also observed for 2-methylbicyclo [2.2.2] octane. * The mixture was provided b y N. A. Belikova.
162
YE.
I . B A G R I I et al.
HYDROCARBONS ISOLATED FROM A 7 0 - 1 8 0 ° PETROLEUM FRACTION OF THE B A L ~ K H A N S ~ r DEPOSIT BY EXTRACTIVE CRYSTALLIZATIOl~ W I T H THIOUREA (EXTRACT I I )
Relative retention volume at 80 ° on No.
1 2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 20
Hydrocarbon
c/s-Bicyclo [3.3.0] octane Bicyclo [3.2.1] octane Bicyclo [2.2.2] octane 1-Methyl-c/s-bicyclo [3.3.0] octane 1-Methylbicyclo [3.2.1] octane 1-Methylbicyclo [2.2.2] octane endo-3-Methyl-cis-bicyclo [3.3.0] octane exo.2-Methyl-cis-bicyclo [3.3.0] octane exo-3-Methyl-cis-bieyclo [3.3.0] octane exo-3-Methylbieyclo [3.2.1] octane exo-6-Methylbicyclo [3.2.1] octane endo-2-Methyl-cis-bicyclo [3.3.0] octane 8-Methylbicyclo [3.2.1] octane endo-2-Methylbicyclo [3.2.1] octane 2-Methylbieyclo [2.2.2] octane endo-6-Methylbicyclo [3.2.1] octane trans-Bicyclo [4.3.0] nonane exo-2.Methylbicyclo [3.2.1] octane cis-Bicyclo [4.3.0] nonane Bicyclo [3.3.1] nonane and (or) bicyclo [3.2.2] nonane
Relative content (°/o) in the extract calculated from a chromatogram on dibutyltetrasqualane chlorophthalate
squalane
dibutyltetrachlorophthalate
100.0 110.1 114.9
100.0 108.8 111.5
15.6 12.4 1.7
16.2 12.4 2.0
125.3 139.5 150.1
124.0 139-6 149.$
5.6 9.7 3.6
6"1 9.5 2.4
152"5
145"4
4.1
2.3
154"9
153.1
7.6
8.9
163.1
158.2
4.5
3.3
170.6
164.7
1.6
2.0
178.5
175.1
2.6
2-5
193'0 193.7
189.7 189'7
1.8 1.9
2.5
196.5 200.4
198.5 194.5
3.6 2.0
3.9 2.9
209.2 213.6
202.0 224.7
2.6 3.0
0.5 6.7
216.5 274.6
214.5 272.8
1.5 9.1
1.4 9"4
312.0
302.0
5.5
5.1
A n i n c r e a s e i n t h e c o n t e n t o f endo-6-methylbicyclo [3.2.1] o c t a n e ( T a b l e , N o . 16) d u r i n g s e p a r a t i o n i n s q u a l a n e , o f trans-bicyclo [4.3.0] n o n a n e ( T a b l e , N o . 17) i n d i b u t y l t e t r a c h l o r o p h t h a l a t e a n d s o m e o t h e r h y d r o c a r b o n s ( T a b l e ) p r o v e s t h a t i n s e p a r a b l e i m p u r i t i e s a r e p r e s e n t i n t h e s e cases. F o r m o s t h y d r o c a r b o n s t h e d i f f e r e n c e o f c o n t e n t i n e x t r a c t s I I is n e g l i g i b l e w h e n t h e chromatograms are calculated for different phases. A quantitative calcula-
Hydrocarbon eomposltion of extraets from petroleum fractions
163
tion of ehromatograms was carried out using a system of internal standards. I n those few eases w h e n t h e s e p a r a t i o n of p e a k s was n o t clear (e.g. p e a k No. 10, F i g u r e a) a v a l u e equal to 0.75 of t h e height of t h e p e a k was a s s u m e d in the calculation. T h e a u t h o r s are grateful t o A. F. P l a t e a n d N. A. Belikova, w h o k i n d l y p r o v i d e d bieyelo [3.2.2] n o n a n e a n d exo-8-methylbicyclo [3.2.1] o c t a n e specimens. Ye. I. A m o s o v a t o o k p a r t in t h e e x p e r i m e n t a l p a r t o f t h e s t u d y . SUMMARY
I. Repeated extractive crystallization with thiourea can be used for rapid qualitative determination of methylsubstituted bicyclic C9 saturated hydroc a r b o n s in gasoline p e t r o l e u m fractions. 2. I n a gasoline f r a c t i o n of p e t r o l e u m from t h e N a d k i r m a k i n s k s a n d s t r a t a o f t h e B a l a k h i n deposit t w e n t y C8-C 9 bieyclic h y d r o c a r b o n s were found. More t h a n half o f t h e h y d r o c a r b o n s identified were n a p h t h e n i e h y d r o c a r b o n s
which contain bridge bonds. Translated by E. SEY~RE REFERENCES ]. M. BE~FI~RIDGE, Oil and Gas J. 62, No. 37, 130, 1964
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