Hydrocarbons of Khar'yag crude oil

206

E. KH~ KURASHOVAet al.

of their origin. As regards the qualitative and quantitative distribution o f naphthenic hydrocarbons, the crude oils studied can be subdivided into five chemical types: B-2i, B-2ts, B:lm, B-lb, and B-lt, differing in the concentration of isoprenoid alkanes and mono-, bi-, and tricyclanes. It is suggested that change in the crude oils in the B-2i-~ - , B - l t series is a consequence of biodegradation processes, which occur with different degrees of intensity. REFERENCES

1. A.A. PETROV, Uglevodorody nefti (Petroleum Hydrocarbons), p. 263, Nauka, Moscow, 1984 2. I. M. SOKOLOVA, S. S. BERMAN, N. N. ABRYUTINA et al., Neftekhimiya 29) 2, 147) 1989 3. J. S. RICHARDSON and D. E. MILLER, Anal. Chem. 54, 765, 1982 4. N. S. VOROB'EVA, Z. K. ZEMSKOVA and A. A. PETROV, Neftekhimiya 26, 5, 579, 1986 5. A. M. KULIYEV, A. A. PETROV, A. M. LEVSHINA et al., Azerb. khim. zhurn. 2, 48, 1984

Petrol. Chem. U.S.R.R. Vol. 29, No. 3, pp. 206-220, 1989 Printed in Poland

0031-6458/89 $10.00+.00 ~ 1990 Pergamon Press pl¢

H Y D R O C A R B O N S OF KHAR'YAG CRUDE OIL* E. KH. KURASHOVA,I. A. MUSAYEV,M. B. SMIRNOV,R . N . SIMANYUK,A. I. MIKAYA, A. V. IVANOV and P. I. SANIN A. V. TopchiyevInstitute of Petrochemical Synthesis, U.S.S.R. Academy of Sciences, Moscow (Received 23 March 1989)

THE present paper presents the results of investigating h)drocarbons of highel fractions o f crude oil. The investigation was conducted on a 320°-500QC fraction (vacuum gas oil) of crude oil from the Khar'yag field (Arkhangel'sk region), sampled from a depth of 2578-2516 m. Khar'yag crude oil is noted for a high paraffin content (21%) and a low concentration of sulphur compounds (0.32 700 sulphur) .and resins. The overall characteristics of the crude off were given in [1]. The yield of 320 °500°C fraction amounted to 25.3 ,%. After aromatic hydrocarbons (adsorption chromatography, silica gel) and n-paraffins (molecular sieves) had been isolated from the 320°-500°C fraction, the concentrate containing alkanes of branched stlucture and cyclanes was separated by complexing *Neftekhimiya 29, No. 5, 616-627, 1989.

.

.

.

.

.

.

Hydrocarbons of Khar'yag crude oil

,207

Scheme for investigating crude oil 320°-500°C fraction I Adsorption chromatography on silica gel

I

Alomatic hydrocarbons (20.4 ~ )

Alkanes of normal and bianched structure, cyclanes (79.6~)

4,

I

Mass spectrometry

Molecular sieve treatment I

4, Alkanes of brached structure, cyclanes (47.8 %)

4,

n-Paraffins (31.8 ~)

I

t

Complexing with Carbamide

GLC

!

Hydrocarbons forming an adduct (8.5~)

Hydrocarbons not forming adduct (39"3yo)

4,

I

GLC, chromato-mass spectrometry, NMR spectroscopy

Complexing with thiocarbamide ]

I

4. H~drocarbons forming adduct (7"5~o)

4.

Hydrocarbons not forming adduct (31"8Yo)

I

I

Dehydrogenation

Dehydrogenation

Aromatic hydrocarbons, alkanes of branched structure, non-dehydrogenated cyclanes

Aromatic hydrocarbons, alkanes of branched structure, non-dehydrogenated cyclanes

I

I

Adsorption chromatography on silica gel

Adsorption chromatography on silica gel

I sec-Aromatic hydrocarbons (2.6~o)

4,

I Alkanes of branched structure, nondehydrogenated cyclanes (4"9%) I

4.

sec-Aromatic hydrocarbons (6.9~/o) I

J,

Alkanes of branched structure, icyclanes (24.9 Yo)

4,

GLC, chromato-mass spectroscopy and NMR spectroscopy

'

with urea. Hydrocarbons not forming a complex with urea were treated with thiourea. Then the hydrocarbons forming and not forming an adduct with thiourea were dehydrogenated. Dehydrogenation was used to produce aromatic hydrocarbons from hydrocarbons containing hexamethylene rings, Of course, not all the hexamethylene rings are dehydrogenated in this case, From the structure of the secondary aromatic (see-aromatic) hydrocarbons obtained it was possible to judge the structure of the initial naphthenic hydrocarbons undergoing dehydrogenation. During the investigation, use was made of different analytical methods: chromatography, clnomato.mass spectrometry, and 13C NMR spectroscopy. AROMATIC HYDROCARBONS

Aromatic hydrocarbons isolated by adsorption chromatography on silica gel were analysed by the method given in [2] on an MKh-1320 mass spectrometer with an energy of the ionizing electrons of 70 eV and an ion source temperature o f 250°C. Specimens were introduced directly into the ion source at 150°C. . . . . . . . Analysis of the aromatic part of the 320°-500°C fraction is set outbdow: Alkylbenezes 33.3 wt.~o Indans, tetralins 14-2 wt.Yo Dicycloalkanobenzenes 6.7 wt.Yo Naphthalenes 8.9 wt.Yo Acenaphthenes,diphenyls 5.5 wt.~o Fluorenes 4.5 wt.Yo Phenanthrenes, anthracenes 14.9 wt.~o Cycloalkanophenanthrenes 3.9 wt.~/o Pyrenes 5.4 wt.Yo Benzothiophenes 0.4 wt.Yo Dibenzothiophenes 0.2 wt.~o Naphthobenzothiophenes 2.1 wt.yo

....

The content of aromatic compounds in the 320°-500°C fraction amounted to 20"5 wt. ~o. Of the aromatic hydrocarbons, alkylbenzenes are present in greatest quantity (33.3 wt.%). Bicyclie aromatic hydrocarbons (naphthalene derivatives), tricyclic aromatic hydrocarbons (phenanthrene derivatives), and tetra~.Tclie aromatic hydrocarbom (pyrene derivatives) were also discovered. Hydrocarbons of mixed structure were found, containing cydopentane and cyclohexane rings as well as the benzene ring, and also heterocyclic compounds containing sulphur (thiophene derivatives).. n-ALKANES

n-Alkanes (39-9 wt. Yo) were isolated from the 320°--500°C fraction by molecular sieves [3]. The inddvidual composition and content of n-alkanes was determined by gas-liquid chromatography on a Tsvet-2 chromatograph with a plasma-ionization detector (25 m x 0-25 ram, stationary' phase Apiezon L, carrier gas hydrogen, tern-

Hydrocarbons of Khax'yagcrude oil

209~.

TAms 1. C o N ~ r ov Ja.r~Bs (wt.~o) xN 320~-500°C F~cr~N n-Alkane

Per sum of n-alkanes

. .

Per 320-500°C n-Alkane fraction

Per sum of n-alkancs

C~sH~s

0"9

0"3

C~THss

8"2

C~9H4o CaoH42

9"9 9"4

3"1 3"0

C2.Hss C~gHso

6"6 5"3

C~1H~4 C~2H4~ C~sHte C2,Hso CzsHea C~eHs,t

8"8 8'8 8"5 I0"1 9"4 8"8

2"8 2"7 3"2 3"0 2"8 2"8

C3oHe2 CslHe4 C32Hee C3sHes C3,tH~o

" ......

2"8 1"6 0"6 0"3 <0"1

Per 320_500oc fraction '

2"6 2"1 1"7

0"9 0"5 0"2 0"1 <0-I

perature programming from 160 ° to 315°C at rate of 2 dug/rain). The results of analysis are given in Table 1. .... From Table 1 it csn be seen that C19-C28n-alkanes are present in greatest quantity (88 wt. %), their ~ n t e n t in the fraction being more or less identical.

ALKANES OF BRANCHED sTRucTURE AND CYCLANES After aromatic hydrocarbons and n-alkanes had been removed from the 320 °500°C fraction, alkanes of branched structure and cyclanes remained. As is known, it is this mixture of higher hydrocarbons of crude oil that is most complicated to investigate, especially as it is difficult to separate. In thepresent study, particular attention was l:aid to analysing these hydrocarbons. In the 320%500°C fraction, the mixture of branched alkanes and cyclanes amounted to 45.6 wt. ~o. The group composition of these hydrocarbons (wt. ~o), determined by means of mass spectrometry (the instrument and conditions for analysis have been described above), was as follows: Alkanes of branched structure 50.0 Cyclanes: monocyclic 16.5 bicyclic 8.5 tricyclic 11.3 tetracyclic 6-8 pentacyclic 3-2 hexauyclic 3"7 Thus the isolated fraction contains 50 wt. ~o alkanes of branched structure and 50 wt.~o cyclsnes (naphthenes), mono-, bi-, and tricyclic hydrocarbons comprising 36"3wt.~o. The structure of the branched alkanes and the a]kyl substituents of the cyclanes Was further studied by the lsC N M R method [4]. Spectra were recorded on a Bruker WP-80DS spectrometer with a working frequency of 20.115 MHz. The conditions of recording were as tollows: ZH broad-band suppression, accumulation storage vol-

No.

79 73 13

CHaCH2CH2CH2CHzCH2-

CHa CH2 CHzCHzCHzCHaCH2-

CHaCHCH2CHzCHz-

CH3

CHs

4"0

CHaCH2CH2CHaCHzCH-

CHa

5"5

7"0

7"0

5"3

:

CHaCH2CH2CHzCH-

CHa

1

CH3CH2CH~CHCH2CH2-

CHa

I

CHaCH2CHCH2CH2-

CHa

CH3CHCHzCHzCH2CHCHa-

CH3

CHaCHCHzCHzCHzCH2-

CH3 7"0

93

I

104

CH3CHzCH2CHzCH2-

fins

thenes + isoparaf-

CH3CHzCH2CH2-

•

Structural fragment

Naph-

3"5

4"0

5"5

12"0

<0"3

18.5

18"5

113

109

119

121

with urea

1

i

6"1

3"9

10.7

12"3

14"8

6"7

21'5

60

65

77

79

initial

-

2"0

3"8

2-6

2"8

5"5

-

66

76

83

dehydrogenated

with thiourea

6"2 .

3"2

15"5

20"0

17.0

11 "5

26

-

75

95~

89 .

noa-dehydrogenated

Hydrocarbons forming adduct

I

5"0

4"0

8.2

4"5

4,0 .

3"4

8q

66

76

93

100

initiai

-

2"0

-3.3

-

2"9

1,8

5'0

. 59

71

87

.....

_

-

4i0

616

:

5"4

5.2

3"4

9-4

70

88

i051

111

dehydro- non-dehygenated Idr°genated

with thiourea

Hydrocarbons not forming adduet !

TAnLe 2. ISOPAgAr~S AND CYCLANESOF 320°-500°C FRACTION N u m b e r of structural fragments for 100 average molecules of hydrocarbons (13 C N M R )

~

o

~"

.t'rl"

~2

CHa

~/~H2CH2CH~CHz-

D--CHr

20

21

~ ~ H z C H 2 -

19

C2H5

I

--CH2CH2CHCHzCH~-

C2H5

CHaCH2CHCH2CH2-

~-x/~-"CH2"

1

CHa

CHa

~CHzCHCHzCH2CHzCHzCHCH~-

CHa

--CH2CHCH2CH2 CH2 CHCH2-

CH3

--CH2CH2CH2CHCH2CHaCHa-

CH3

1

--CH2CH2CHCH2CH~-

Structural fragment

18

17

16

15

14

13

12

No.

-

8"2

8-2

5"2

6"2 2-7

5.2

<0"2

< 0'4

<0"7

<0"3

23-5

30.5

9"5

3"3

0"6

0"8

16"0

30"5

37.5

3"2

3.6

16"4

16"4

1"5

0"8

3'5

48

63

84

initial

-

1"5

0

0

0"3

0'6

.

5-I

7-0

.

.

5'2

5'6

0

0

1'5

1"0

39.5

59

dchydro- non-dehygcnated drogenated 13-0 81

with thiourea

Hydrocarbons forming adduct

thenes + isoparaffins with urea

Naph-

-

.

0"9

2"8

7"5

4"4

0"6

10"8

19.2

28

initial

-

0.75

0

0

3"4

0"3

6.6

17

-

-

1"5

1:8

6"2

0"8

"

14.5

21

"

dehydro- non-dehygenated drogcnated 22 31

with thiourea

Hydrocarbons not forming adduct

o.

~

;~

~0

~"

212

E. Km .KXmASHOVAet al.

ume 8K, reproduction storage volume 8K, machine resolution 0.56 Hz, pulse duration 3.2/~sec (25°C), data collection time 1.092 sec, specimen temperature 35°-40°C. Structural fragments of the alkyl groups of molecules of branched alkanes and alkylcyclanes, which were established by means of lsC NMR spectrometry, are given in Table 2. From the given data it follows that these structural fragments include alkyl groups of normal stxucture C4C7 (Nos. 1-4), methyl-substituted (in positions 2-5) alkyl groups (N0s. 5, 6, 8-I 1), and alkyl groups with arrangement of methyl groups corresponding to isoprenanes (No. 7), the latter being present in considerable quantity. Fragments containing one or two methyl gIoups of the biradical type were also found. All the structural fragments contained only methyl groups as substituents; fragments containing an ethyl group in the side chain (Nos. 16, 17) were found only in very small quantity. The presence of fragments containing hexamethylene and pentamethylene tings (Nos. 18-21) was also established. It should be noted that structural fragments of the type

CH$ I -'CHtCHICCHICHI--

C/Hs

-'~H2CHICH CH CH m

I CHs I CHa

-'CHsCHICI"ICHtCHCHaCHt m

1 CHs

I CHs

were not found with a detection limit of 0.2-0.5 ~o. Certain quantitative data for concentrates of hydrocarbons isolated by adduct formation with urea [5] and thiourea [6] and also obtained by dehydrogenation of the corresponding concentrates (in each case the number of structural fragments was dctmTnined on 100 average molecules of the hydrocarbons) are given in Table 2. Here account must be taken of the fact that when determining structural fragments by means of t3C NMR spectroscopy, for example of a butyl radical (No. 1), a conesponding magnitude is also introduced by other radicals of normal structure (Nos. 2-4). As might be expected, hydrocarbons forming an adduct with urea are noted for an increased content of alkyl fragments of normal structure both in alkanes and cyclanes, and for the absence of isoprenane-typ¢ fragments. The content of individual hydrocarbons forming an adduct with urea was detcrmined. Here, taking account of the influence of the structure of the hydrocarbons on adduct formation, it is possible to proceed from the following assumptions: (1) each cyclane molecule contains a multiatomic alkyl substituent-an alkyl fragment; (2) the branched alkanes and multiatomic alkyl fragments of cyclanes only have methyl substituents. This second assumption is confirmed by the absence in the atkyl fragments even of ethyl substituents. 'We Shall denote the propoition of branched alkanes and cyclanes forming an adduct with urea as A and C. Then the number of end groups of the alkyl chains E will evidently be equal to 2A + C (the alkanes have two end groups) or, assuming that

Hydrocarbons of Khar'yag crude oil

213

A+C=IO0~o, A=C-IO0

(%)

O)

It is evident that E---~I +~5-/-o~s +~ 9

(2)

where ~ is the number of structural fragments, and the subscript to ~ corresponds to the number of the structural fragment in Table 2. The remaining end structural fragments are part of end structurol fragments Nos. 1, 5, 8, and 9. Then E = 156 and A = 56. Averaging the measmed values of ~1 with account taken of relations of the type ~t = ~z + ~xo, we obtain A=57__.5,

C=43_+5Yo

From the data of Table 2 it follows that in the fraction there are no di- and polysubstituted alkanes, nor eycloalkanes with alkyl substituents of branched structure. We shall denote the total number of monomethyl-substituted alkanes as X~, of disubstituted alkanes as X2, as trisubstituted alkanes as X3, etc. Similarly, Yx will denote the total number of eycloalkanes for which the mul iatomic alkyl fragment has one substituent, Y2 the total number of cyeloalkanes for which the multiatomic alkyl fragment has two substituents, etc.

A-- X x + X2 + X3 +...

(3)

The total number of methyl sustituents M of alkanes and multiatomic alkyl fragments of cyclanes is equal to N

M = ~5 + ~s + ~9 + ~la = ~ (iX~+ iY~)

(4)

1=1

Or, with account taken of equations (1)-(3), 100+~13-~1 =X2 +2X3 + ...Ya +2Y2 +.../>X2 +X3...Y1 +Y2 +...

(5)

On the right-hand side of inequality (5) we have the total content of all di- and polymelhyl-substituted alkanes and eyclanes with branched multiatomic alkyl fragments, which is extremely low, since the left-hand side of inequality (5) is equal to 2.5 + 4 (Table 2). Consequently, the overwhelming majority of alkanes in the fractions are monomethyl-substituted, while the cycloalkanes have a multiatomic substituent of normal structure. Then all the branched alkyl fragments given in Table 2 enter the monomethyl-substituted alkanes. Thus the fractions of hydrocarbons forming an adduct with mea contain the following homological series of C1s-C32 hydrocarbons (~o of fraction): 2-Methylalkanes 3-Methylalkanes 4-Methylalkanes 5-Methylalkanes 6-Methylalkanes

18 12 5.5 4-0 3-5

214

E. KH. Kt/RASHOVAet t ~

Other monomethylalkanes 15 n-Alky|cyelopentanes 8-5 n-Alkylcyclohexanes 5.0 n-Alkylcyclopentanes and -cyclohexanes additionally methyl-substituted in ring 25 Polymethylalkanes and cycloalkanes with branched multiatomic substituent ~<5 In the adduct, a series of 2- and 3-methylalkanes are present in greatest quantity, there being more 2-methylalkanes than 3-methylalkanes (see also [6]). As the distance of methyl from the end of the chain increases, the content of methylalkanes decreases insignificantly. A homological series of methyl (n-alkyl)cyclopentanes was found in the crude oil for the first time. Unfortunately, the absence of standard hydrocarbons did not enable the position of the substituents in the ring or the stereochemistry of the molecules to be determined. It should be noted that, as the molecular weight of methyl (n-alkyl)cyclopentanes increases, their retention times (GLC) coincide with those for methylalkanes, which have one more carbon atom. In this way, the composition of the hydrocarbons which, along with n-alkanes, form a complex with urea is determined almost entirely. After the fraction of alkanes of branched structure and cyclanes had been treated with urea, the hydrocarbons not forming a complex with m-ca were treated with thiourea by the procedure of [7]. From Table 2 it can be seen that hydrocarbons forming an adduct with thiourea are noted for an increased content of isoprenanes (fragments Nos. 7 and 14) and alkylcyclohexanes (fragments Nos. 18 and 19). As was established, it is difficult to study these hydrocarbons by GLC. The hydrocarbon mixture of extremely complex composition forms a large "hump" on the chromatogram. Above the hump, among others high peaks corresponding in retention times to n-alkycyclohexanes can be seen. It proved impossible to establish the structure of the hydrocarbons by chromato-mass spectrometry because of the presence in the mixture of a large number of homolytic series of hydlocarbons, the retention times of which often coincide. On account of this, interpretation of the corresponding mass spectra was difficult. Calculation similar to that for hydrocarbons forming an adduct with urea on the basis oi N M R spectroscopy data showed that in the fraction forming an adduct with thiourea the alkanes comprise 25 wt. %, and the proportion of di- and polysubstituted alkanes and alkyl fragments of cycloalkanes of non-isoprenane structure is small.

Even it they enter an isoprenane alkyl fragment, disubstituted structural fragments Nos. 14 and 15 make a contribution to ~13 (equal to ~1,~+~1s). For a further study of the hydrocarbons forming and not forming an adduct with thiourea their catalytiedehydrogenation was carried out (18 % Pt and 2 % Fe on coal, t 315°C [8]). Under these conditions, hydrocarbons containing dehydrogenated 6-membered rings (cyclohexanes not containing quaternary C atoms, and hydrocar-

Hydrocarbons of Khar'yag crude oil

215

boris in which the 6-membered ring does not form part of bridge structures) should be transformed into the corresponding aromatic hydrocarbons. Then the dehydrogenation products were separated by liquid chromatography on silica gel into aromatic hydrocarbons on the one hand and into alkanes of branched structure and cyclanes on the other. The yield of aromatic hydrocarbons amounted to 34.7 wt. ~, and the 5 7

9 11

l

17 19

is I ~ Ira t61fi I,o ,~

=

/ime,hp

10

~2,.19eze 2

b

Time, ~r Cbromatogram of scc-aromatic hydrocarbons obtained by dehydrogenation of hydrocarbons of 420°-500°C fraction that form (a) and do not form (b) an adduct with thourea, a: 1, 3, 3, 7, 9, 11o I3, _I3, I?, 19-C22-C~o alkylbcnzenes; 2, 4, 6, 8, IO, 12, !4, 16, ]8-C22-C3o methyl (n-alkyl)bcnzcncs; b: I-4, 6, 8, IO, I2, I4-Cz~-C~9 methyl (n-alkyl)benzcnes; 3, 7, 9, ]], ]3-C26-C3o

2-phenylalkanes. yield of a]kanes and cyclanes to 65.3 wt. ~ , the yields for the initial 320°-500°C fraction being 2.6 and 4.9 wt. ~o respectively. A:study of the scc-aromatic hydrocarbons obtained from hydrocarbons forming an adduct with thiourca by means of GLC, chromato-mass spectrometry, and N M R

:216

13. Kl~. Kv-aasHovA¢t al.

spectroscopy showed that they consist mainly ot n-alkylbenzenes and methyl (n-alkyl)benzenes ( ~ 85 % of the fraction), the latter comprising hydrocarbons with 1,4-substitution of the ring (accocding to IR spectrometry data). The ehromatogram of the fraction is given in Fig. a. Series of alkylbenzenes in which the alkyl was methyl-substituted in the ~-position (2-phenylalkanes) and dimethyl (n-alkyl)benzenes (evidently 1,3,5-substituted) were also identified in this fraction. In the ease of identifying 2-phenylalkanes and methyl(n-alkyl)benzenes by means of chromate-mass spectrometry, the peaks of the substituted tropylium cations (m/z 105 in the case of monomethyl-substituted aikylbenzeues) and cation radicals (m/z 106) are particularly important [9, 10]:

J n ~n+l

-'CnHln.1

(1

g=.CH~[m//z.105)

|

OCH,~ Ctt,,n,1 1 +" ."Cn.,n.l"

CH2

t

n÷"

7""

CH-K -CHzCHE'

The intensity of the peaks of tropylium ions a is normally higher than the intensity of the peaks of cation radicals b for non-substituted alkylbenzenes in an aromatic nucleus, but the peaks of type b ions are maximum in the spectra for alkylbenzenes substituted in the benzene ring. It was this charactezistic decomposition of substituted benzenes under electron impact that was used to differentiate 2-phenylalkanes and methyl(n-alkyl)benzenes. Unfortunately, it proved impossible to establish the mutual position of substituents in the benzene nucleus by mass spectrometry. In this aromatic fraction there are series of alkylbenzenes in which the alkyl radical is substituted by about 3 wt. ~o methyl in position 2 (counting from the end of the chain), by about 4 wt. % in position 3, and by 2 wt. % in position 4, and also benzenes in which the alkyl radical is substituted by 0.5 wt. % ethyl in position 3, the presence of such homological series being indicated by the presence in z3C NMR spectra of ;the aromatic fraction of signals corresponding to structural fragments Nos. 5, 8, 1l, 14, and 15. The presence of dimethyl(n-alkyl)l~nzenes (evidently 1,3,5-substituted) was demonstrated by means ot chromate-mass spectrometry. Consequently, series of substituted cydohexanes corresponding to these aromatic hydrocarbons were

Hydrocarbons of Khar'yag crude oil found in the crude oil ()__(CHi)nCH3

y",~__CH(CH2)nCH (",/J CH I3 a

("~--(CH2) CH, (",~ CHCH:

217

218

E. Km KtmAmovA et al.

na*ed hydrocmbons forming an adduct with thiourea, alkylbenzenes in this case evidently contained mainly alkylbenezenes with a branched alkyl chain, and also alkylbenzenes additionally substituted in the benzene ring. Differences in the isomer composition of these hydrocarbons were also able to affect the distribution of hydrocarbons. From the given data it follows that mono-, di-, tri-, and tetracyclic cyclanes correspond to particular sec-aromatic hydrocarbons. As shown by the results of analysis by means of GLC, chromato-mass spectrometry, and NMR specroscopy, non-dehydrogenated hydrocarbons forming an adduct with thiourea contain isoprenanes, n-alkylcyclopentanes, methyl(n-alkyl)cyclopentanes, dimethyl(n-alkyl)cyclopentanes, and trimethyl(n-alkyl)cyclopentanes of composition C~s-C32. The group composition of hydrocarbons not forming an adduct with thiourea and non-dehydrogenated hydrocarbons was studied. Among these hydrocarbons, alkanes of branched structure are present in greatest quantity (33.5 wt. ~o), but their investigation by means of GLC and chromato-mass spectrometry indicates that the composition of this fraction is very complex, and identification of its components is difficult. Comparison of the composition of hydrocarbons torming adducts with urea and thiourea showed that if the greater part of the n-alkyleyclopentanes forms an adduct with urea, then the greater part of n-alkylcyclohexanes is found in fraction forming an adduct with thiourea. This indicates that n-alkylcyclohexanes posses a greater capacity to form a complex with thiourea than with urea. The total content of alkylcyclopentanes in the 320-500°C fraction is about 1 wt. ~o, and of n-alkylcyclohexanes 2 wt. ~o. As is known, the content of n-alkanes in this fraction is about 30 wt. %. Thus, use of the proposed hydrocarbon separation scheme together with the most informative analysis methods (GLC, chromato-mass spectrometry, and laC NMR spectroscopy) made it possible to determine homological series of alkanes and cydanes in the crude oil, the structure of which is given below. Some of the given homological series of hydrocarbons were determined for the first time.

CHa(CH,,)nCHa CHa(CH=)CHCHa I

CHa CHa(CH2),,(~HCH,aCHa Ctla(CIt..)nCItCH2CH2CH a I CHa CHa CHa(CH=)n~HC H"CH2CH,aCHa CHa(Ctt=)nCHCH2CHeCH~(:H~CHa I CHa CIIa Ct{a(C[tCtI2CH2CH.0nCHCH.~ 1 i CHa CHa ~ - - ( C H 2 ) n CHa /---~--rCH=) CHCHa k__/ ' ~I CH~

Hydrocarbons of Khar'yag crude oil

219

X~__/~--(CH2),,~HCH2CH3 k~/--(C H2)n~HCI/9.CH2CI{3

CH3

CH3

C2Ils

CH3

CH~

CIt~

~C (H n 3 C z )]-I

~-(CH2)nCH3

CH~ ~ - (CH2)nCH3 CH3

[~'-(CH2)nCH:j CH3

~

CH 3

(CH2)nCH3

H3C- ~

CH 3

(CH2)rLCHa

CH:3

The authors are grateful to P. L. Khodzhayeva for IR spectrometric analysis of the fraction. SUMMARY

The composition of hydrocarbons of 320°-500°C fraction from Khar'yag crude oil has been studied. The scheme for separating and investigating the hydrocarbons includes GLC, mass and chromato-mass spectrometry, and '3C NMR spectroscopy, which made it possible to obtain additional information on the composition of branched-structure alkanes and cyclanes of the crude oil. The following series o f alkylcyclanes were found in the crude oil for the first time: alkylcyclohexanes, in which the alkyl contains methyl as the substituent in positions 2, 3 and 4 (counting from the end of the alkyl chain); alkylcyclohexanes, in which the alkyl contains ethyl as the substituent in position 3; 2-cyclohexylalkanes; dimethyl(n-alkyl)cyclohexaries; mono-, ~-, and trimethyl(n-alkyl)cyclopentanes. REFERENCES I. N. M. ZHMYKHOVA, K. A. DEMIDENKO and V. P. KOLESNIKOVA, Khimiya i tekhno. logiya topliv i masel, 6, 25, 1987 2. A. A. POLYAKOVA, Molekulyarnyi mass-spektral'nyi analiz neftci (Molecular Mass.spectral Analysis of Crude Oils), p. 180, Nedra, Moscow, 1973 3. J. V. BRUNNOCK, Anal. Chem. 38, 12, 1648, 1966 4. M. B. SMIRNOV and A. M. KRAPIVIN, Metody issledovaniyasostava organieheskikh soyedinenii neftei i bitumoidov (Methods for Studying Composition of Organic Petroleum Como pounds and Bitumoids), p. 138, Nauka, Moscow, 1985 5. A. V. TOPCHIYEV, L. M~ ROZENBERG, Ye. M. TERENT'YEVA et aL, Sostavi svoistva

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M . B . SMmNOV and YE. B. FRoz~3v

vysokomolekulyarnoi chasti nefti (Composition and Properties of High-Molecular Part of Crude Oil), p. 208, Izd. AN SSSR, Moscow, 1958 6. A. A. PETROV, Uglevodorody nefti (Petroleum Hydrocarbons), p. 55, Nauka, Moscow, 1984 7. A. L. LIBERMAN,D. B. FURMAN and Ye. I. MIL'VITSKAYA,Neftekhimiya13, I, 145, 1973 8. S. R. SERGIYENKO and Ye. V. LEBEDEV, Izbiratel'naya kataliticheskaya degidrogenizatsiya vysokomolekulyarnykhuglevodorodov (Selective Catalytic Dehydrogenation of High-Molecular Hydrocarbons),73 pp., Izd. AN TSSR, Ashkhabad, 1961 9. N. S. VUL'FSON, V. G. ZAIKINand A. M. MIKAYA,Mass-spektrometriyaorganicheskikh soyedinenii (Mass Spectrometry of Organic Compounds), p. 312, Khimiya, Moscow, 1986 10. Organicheskayageokhimiya(OrganicGeochemistry),(Eds. G. Eglintonand M. T. S. Murphy), 487 pp., Nedra, Leningrad, 1974

Petrol. Chem. U.S.R.R. Vol. 29, No. 3, pp. 220-229, 1989 Prtnted in Poland

0031-6458/89 $10.00+ .00 0 1990 Pl~rgo.monP r~ i plo

USE OF IH NMR SPECTROSCOPY TO STUDY PETROLEUM ALKYLCARBAZOLES. POLYMETHYLCARBAZOLES IN A CCI4-~CDCI3 MIXTURE * M. B. SMmNOVand YE. B. FROLOV A. V. TopchiyevInstitute of Petrochemical Synthesis, U.S.S.R. Academyof Sciences, Moscow

(Received 10 January 1989) THE promise of using PMR spectroscopy for analysing the composition and structure of petroleum alkylcarbazoles was demonstrated in [I, 2]. From the given ~H NMR spectra of carbazole (I), 1-, 2-, 3-, and 4-methylcarbazoles (II-V), 1,2-, 1,4-, 1,5-, 1,8-, 2,3-, 2,4-, 2,6-, and 3,4-dimethylcarbazoles (VI-XIII) in an inert solvent (a 2 : 1 (by vol.) CC14+ CDCIa mixture) it follows that for dimethylcarbazoles the effect of methyl substituents on chemical shift of protons is additive. Protons in the ortho-position to the substituents in compounds VI, X, and XII (with CH3 groups occupying neighbouring positions in the ring) and H5 in XIII are the exception [2]. In the present paper, chemical shifts and spin-spin interaction constants (SSIC) of tH nuclei of a series of tri-, tetra-, and pentamethylcarbazoles XIV-XXIX in the same solvent were measured to establish the degree of additivity of the effect of methyl substituents on the position of multiplets of protons of the aromatic rings and CH3 * Neftekhimiya29, No. 5, 644-651, 1989,