Catalytic synthesis of compounds of benzthiophen series

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Petrol. Chem U.S.S.R. Vol. 21,1~o. 8, pp. 148-150,1981 Printed in Poland

O 1982 PergamonPress Ltd.

CATALYTIC SYNTHESIS OF COMPOUNDS OF BENZTHIOPHEN SERIES* M. V. VAOABOV I)aghestan Polytechnic

(Received 16 June 1980)

ComPosrrE treatment of raw material is one of stressing problems in petroleum and carbon chemistry; investigations in the field of catalytic conversions of sulphur compounds of petroleum and carbon are therefore of particular importance. It is known that mono- and bicyclic sulphides with a varying dimension of the sulphur-containing ring represent ia significant proportion of sulphur compounds made from Soviet petroleum; these, however, so far, receive limited application. Benzthiophen derivatives are used at the same time as dyes, antioxidant additives, physiologically active substances, drugs , etc. Development of methods of dehydrogenation and dehydroisomerizati6h 6f cyclic sulphides to corresponding benzthiophen compounds is therefore o f definite interest.~ Traditional catalysts of these reactions are inapplicable here. A study was made in this paper of catalytic conversions of compounds of 2,31dihydrobenzthiophen and 2,3-dihydrobenzthiopyrane (thiochromane) on aluminosilicate industrial catalysts (Table 1), in order to develop a method for catalytic synthesis of compounds of benzthiophen series. TABLE 1. CHAP..A.CTE~ISTICS OF CATALYSTS

p K × 10 -s s,mmole/mg Specific ..... Catalyst

surface,

mVg ASC LZABC ASC--Na+

~-AI,03

381 394 366 274

pK~

pK0

--8'2 --5'6 --3"0 +3"31~-~H0 --13"3 --13"3 --8.2 --5.6 --3"0 +3"3 1+4.0] --6.63 f 0.8 0'5 0.1 0.0 1.6 3"0 0"8 • 0.5 O'O 0"0 0.0

1"0 0"5 0.4

0.3 0.1 0-4

0.1 0.0 0.4

1.3 0.8 0.8

2'7 0"0 1"4 0"0 2.0 L 0"0

1.4 0.0 0-0

EK,, 1"3 1.4 0-0 0.0

Experiments were carried out using a microcatalytic pulse device under non-chromatographic conditions and in a continuous device with an integral reactor in helium or nitrogen in the temperature range of 250-500°C. Catalyzates were analysed by gas-liquid chromatography and chromato-mass-spectromerry ("Varian", MAT-111, "Grom"). * N e f t e k h i m i y a 21, No. 4, 619-624, 1981. 143

144

M . V . VA~ABOV TABLE 2. TRA~SFOltY£kTIONSOF 2"3-DIKlrDROBENZTHIOPHEI~S

Initial compounds

2-Methyl-2,3-dihydrobenzthiophen

Catalyst

t.

ASC

°C

300

350

400

LZABC r F

silicate (Crimean)

300350 400

ASC

300

~Tatttral ah~mi~o-

2-Ethyl-2,3.dihydrobenzthiophen

250 300

350

400 LZABC 250 300 350 400 300 400

Crimean aluminosilicate

Conversion products. ~o be~tzthiothir)ehrophens l~lan*

v, hr -1

Oatalysate yield, %

0.2 0.4 0.8 0-2 0-4 0"8 0.2 0.4 0.8 0.4 0.4 0.4 0"4 0.4

96 97 98 96 96 97 94 95 96 98 97 95 98 98

70 66 89 84 82 94 83 83 64 80 93 12 15

0.2 0.7 0-2 0.7 0.2 0-7 0.3 0.3 0.3 0.3 0.3 0.3

94 96 93 96 93 94 97 94 94 93 99 98

55 50 53 46 60 55 36 52 63 72 10 25

75

....

.... ------

=-29 24 29 32 23 26 15 23 27 21 5

A l u m i n o s i l i c a t e s a p p e a r e d t o b e h i g h l y effective c a t a l y s t s b o t h i n d e h y d r o g e n a t i o n o f 2 , 3 - d i h y d r o b e n z t h i o p h e n s a n d i n d e h y d r o i s o m e r i z a t i o n o f thioe h r o m a n s . O v e r a l l y i e l d s o f b e n z t h i o p h e n s w e r e 8 0 - 9 0 a n d 6 0 - 7 0 °/o, r e s p e c t i v e l y ( T a b l e 2).

S

R

•

R;

$ where R--H,

CHs, C2H5; R ' = C H a ,

C a l l 5.

R'

Catalytic synthesis of compounds of benzthiophen series The high stability and selectivity of action of aluminosilicates should be noted (Figure) . In catalyzates obtained from experiments of conversion of 2-methyland 3-methyl-2,3-dihydrobenzthiophens products of migration of the methyl group from position 2 to position 3 and vice versa are present, as well as products of dehydrogenation; of the two compounds 3-methyl-2,3-dihydrobenzthiophen undergoes isomerization somewhat more readily. This is, apparently, due to higher hydride mobility of the hydrogen atom in position 2 of the 2,3-dihydrobenzthiophen molecule. With an increase in temperature, the yield of products of dehydrogenation increases, while the yield of products of isomerization decreases. It is obvious that of the two competing processes dehydrogenation takes place at a higher rate, which is due to the formation of an aromatic benzthiophen structure more favourable from an energy point of view.

% I00

I~::~~~

I

60'-

3

qO 20 i

2

t

I

6

I

I

10

J

I

14

I

I

I

t8 f, hp

Dependence of the degree of conversion of bicyelic sulphides on the time of operation of catalysts: t 350°C; ~ 0.4 hr; 1--2-ethyl-2,3-dihydrobenzthiophen: 2--2-methyl-2,3-dihydrobenzthiophen; 3--2-methylthioehroman; d--thiochroman; 400°C, v=0-3 hr; catalysts: 1,2,4--ASC; 3--LZABC. In contrast with 2- and 3-methyl-2,3-dihydrobenzthiophens, 2-ethyl-2,3dihydrobenzthiophen in contact with a!uminosilieate catalysts not only undergoes dehydrogenation, but also skeletal isomerization with a widening of the sulphur-containing ring to form 2-methylthiochroman

S

C2Hs S

CHa

146

M.V. VAOABOV

With an increase in experimental temperature both in continuous and pu]s(, devices, the yield of benzthiopheils ilwreases, while the yield of 2-methylthi<)chroman passes through a small maximum which, as will be shown, is due |,, subsequent dehydro-isomerizatiol ~, to 2-ethy/benzthiophen on increasing temperature. The degree of conversion of 2-ethyl-2,3-dihydrobenzthiophen is somewhai: higher in the entire temperature range examined than for 2- and 3-methytbenzthiophens and particularly ibr 2, 3-dihydrobenzthiophen, which is evideI)c( ~ of the effect of the position of alkyl substituent in the heterocyclic ring and its ([imension on the reactivity of 2,3-dihydrobenzthiophens. Talfie 3 shows effective rate constants of dehydrogenation of 2,3-dihydrobenzthiophens on ASC a~ld LZABC (;atalysts,* from which it tbllows that LZABC has higher activitv. TABLE

3.

EFFECTIVE

RATE

CONSTANTS

OF DEHYDB, OGE~ATION

OF 2.3-DIHYDROBE.NZ-

THIOP:H-E/qS ]ceiI X ] 0 ~, ~'~ffOLE/PA.sEC'G

Catalyst

t, "C

3-Methyl2-Methyl2-Ethyl2,3-Dihydro- 2,3-dihydro- 2,3-dihydro- 2,3-dihydrobenzthiophen benzthiophen benzthiophen benzthiopheh

300 350 400 450 500 350

ASC LZABC

2'0i0.4 3.1£0.2 4.3±0.3 6.0±0.2 7.6~0.5 14.7~:0.3

6-3=[=0.2 8.8±0.4 11.3=[=0'6 16.3+0.4 20"9i0'7

6-7~0.3 9.6+0"5 12.5±0"4 16-4±0"9 23.5±0-9 29.4±0.8

6.7:L0.1 10.4+0.3 16.4=[=0.4 31.0___0.4 --4

33.5±0.6

With regard to the ease of dehydrogenation on aluminosilicate catalysts in the temperature range studied (300-500°C) 2,3-dihydrobenzthi()phens occupy the following order:

i"

I s

> C.,Hs

~

> S

CHs

S

\S ~

To determine the effect of the type of acidic centre on reactions, study was made of conversions of 2-methyl- and 2-ethyl-2,3-dihydrobenzthiophen on ASC treated with quinoline and of y-alumina. Experiments showed that on catalysts with only aprotic centres (ASC--Na = and ASC treated with quinoline) processes of dehydrogenation and dehydro* ASC--aluminosflcate; LZABC--low-zeolite aluminosilicate bead catalyst.

147

Catalytic synthesis of compounds of benzthiophen series

isomerization take place with widening of the heterocycle, while position isomerization does not take place. A typical feature of the behaviour of six-membered sulphur-containing condensed heterocyclic compounds in contact with alumino-silicate catalysts is their isomerization and dehydroisomerization with narrowing of the heterocyclic ring to form corresponding condensed five-membered heterocyclic compounds (Table 4). TABLE 4. ~OI~VERSIONS OF TB'IOCHROMA~S

Products of conversion,.

% Initial compomld

Catalyst

t~ °C

I Thiochroman

ASC

400 450 500

ASC

2-Methylthiochroman

LZABC

300 350 400 450 300 350 400

0.2 0.6 0.2 0.6 0.2 0.6 0.4 0.4 0.4 0.4 0.4 0.4 0.4

2,3-diCatalysate benzthio- hydrobenzyield phens thiophens 96 98 93 94 88 91 98 97 96 95

24 17 49 45 64 53 8 46 54 62

96 95 93

27 55 6O

1 2 2 2 2 10 9

3 7 8

6

I t should be noted that conversions of condensed sulphur-containing six-membered heterocyclics have a higher temperature threshold, compared with five-membered ones. With an increase in experimental temperature, the yield of products of isomerization of thiochromans decrases, while the yield o f products of dehydroisomerization and the overall degree of conversion increases. The yield of hetero-aromatic compounds reaches 6 0 - 7 0 ~ . Substituted thiochromans are converted more readily than thiochroman itself. Using aluminosilicate catalysts with a different ratio of proton and aprotic centres it could be shown that aprotic centres of average strength (pX ranging from 3 to 8) are the only active centres taking part in skeletal isomerization and dehydroisomerization of thiochromans. Special features of transformations studied using condensed sulphur-containing heteroeyclic compounds, the effec:t of the strength and type of acid centres and kinetic reaction mechanisms suggest ari ionic mechanism for the separation of a hydride-ion from t h e substrate b y the action of aprotic centres of catalysts.

t48

M . V . VAOA.BOV

The mechanism of dehydrogenation and skeletal isomerization may be presented by the systems:

R

H

~)

.,

\s/Xtl l/

~ [ +H-

I

I

|~ J

\ s .~.\ C..,H~

~•- [re\/\ \ J \ ./..\'+ l S

CH~

~/\ t~)\/!\ S

CH.~ /

, IL v a %/'-,,S/XH +H-

(~\CH~I~

t,), S

S/ \ CH.:B

~'/\S/\CHtR where R = H , CHs. The ionic mechanism of dehydrogenation and isomerization on aluminosilicate catalysts is also supported by results of UV spectroscopic investigations [3]. To obtain further information about the type of intermediate compound formed during adsorption and on specific features of adsorption of condensed sulphur-containing heterocyclic compounds on aluminosilicates, a study was made of H - D exchange between molecules of 2,3-dihydrobenzthiophens and OD groups of a deuterated ~_SC sample. From the analysis of mass-spectra of exchange products it was established that H-I) exchange takes place mainly (in contrast with e.g. indene) in position 2 of the sulphide molecule, which is due to a strong interaction of sulphur atoms with acidic centres of the catalyst. This results in an orientation of sulphide molecules during adsorption, in which hydrogen atoms at the carbon atom in position 2 are nearer to the surface of the adsorbent than in position 3. Investigation therefore indicates that industrial alominosilieates are highly effective catalysts in dehydrogenation and dehydro-isomerization of compounds of 2,3-dihydrobeazthiophen and thiochroman.

Catalytic synthesis of compounds o f benzthiophen series

149

Dehydrogenation of 2,3
The compounds studied were synthesized by well-known methods: 2,3~tihydrobenzthiophen by a method previously described [4], 2-methyl-2,3-dihydrobenzthiophen and thiochroman by different methods [6], 3-methyl- and 2-ethyl-2,3-dihydrobenzthiophens, according to a recent investigation [7] and $-methylthiochroman by another description [8]. Physical and chemical characteristics corresponded to results in the literature [5, 7, 8]. To investigate catalytic conversions of 2,3-dihydrobenzthiophens and thiochromans, catalysts of the following composition were used (wt. ~): industrial aluminosilicate catalyst (ASC) 88.0 SiOz; 11.0 AltOs; 0.6 CaO; 0"3 Na,0; industrial low-zeolite aluminosilicate bead catalyst (LZABC) 87.0 SiOs; 10.8 AlsO,; 0.4 FesOs; 0.8 CaO; 0.9 NasO; natural Crimean aluminosilicate 77-2 SiOs; 16.7 AlsOs; 2.7 FesOs; 0.8 CaO; 2.6 MgO. SUMMARY

1. A study was made of catalytic transformations of condensed five- and six-membered heterocyclic compounds containing sulphur in contact with industrial aluminosilicate catalysts (ASK and AShKNTs), natural Crimean aluminosilieate and modified alumiuosilicate catalysts. It was found possible to use ASK and AShKNTs as effective catalysts in dehydrogenation and dehydro-isomerization of sulphur compounds. 2. 2,3-Dihydrobenzthiophens in contact with aluminosilicate catalysts are dehydrogenated with high yields (up to 09%) to form corresponding benzthiophens. 3. Thiochromans in contact with alumiuosilicates undergo isomerization and dehydro-isemerization with narrowing of the hetero-ring to form corresponding compounds of benzthiophen series. REFERENCES 1. M. A. PARFENOV, M. K. LYAPINA, Ye. S. BRODS1K17 and Ye. 8. NllglTINA, Neftekhimiya 17, 156, 1977 2. M. V. VAGABOV, Ye. A. VIKTOROVA Ye. A. KAR2,1rwANOV, A. 8h. RAMAZAN0V, Vestn. Most. un-ta, ser. 2, khimiya 18, 457, 1977 3. V. I. LYGIN, E. A. KAI~KRA_NOV, M. V. VAGABOV, N. A. ZUBAREVA, G. G. A~ETOV and A. Sh. RAMAZANOV, Vestn. Most. un-ta, eer. 2, khimiya 19, 604, 1978

150

A.N.

P A U ~ K U et al.

4. F. G. BORDWELL and W. H. MCKFJJJN, J. Amer. Chem. Soc. 78, 2251, 1951 5. B. V. AIVAZOV, S. M. PETROV, V. R. KHAIRULINA and V. G. YAPRYNTSEVA, Fizikokhimicheskiye konstanty seroorganicheskikh soyedinenii, ]). 48, Khi~rfiya Moscow, 1964 6. H. KWART and E. R. EVANS, J. Organ. Chem. 31, 413, 1966 7. Ye. N. KARAULOVA, D. M. MEILANOVA and G. D. GAL'PERN, Zh. obshch, khimii 29, 662, 1959 8. J. C. PETROPOULOS, M. A. MCCALL and D. S. TARBELL J. Amer. Chem. Soc. 75, 1130, 1953

Petrol. Chem. U.S.S.R. Vol. 21, ~No. 3, pp. 150-155, 1981 Prinsed in Poland

0031-8458/81/040150-06507.50/0 © 1982 Pergamon Press Ltd.

STUDY OF THE CHEMICAL COMPOSITION OF POLAR COMPONENTS OF A S P H A L T ~ R E S I N COMPOUNDS OF PETROLEUM* A. N. PAUKKU, I. A. POSADOV, D. A. ROZV.NTAT/, N. V. SmOTINK~ and L. A. KORNIT,OVA Lensovet Technological Institute, Leningrad

(Received 16 July 1980) THE importance of the problem of intensified refining of oil is beyond a n y doubt. The complexity of this problem is determined mainly by the existence in the high-boiling residual petroleum raw material of a considerable amount of hetero-atomic and metal-containing compounds. These compounds have a negative effect on various stages of catalytic processes of refining petroleum, accelerate the wear of technical equipment, reduce the operational indices o f oil products, etc. [1]. On the other hand, resin-asphalthene substances of oil (RASO), particularly their polar components m a y be of undoubted interest as a possible potential natural source of hetero-organic substances. Components of RASO enriched in hetero-organic compounds, are promising for the synthesis of composite organo-metallic compounds suitable for use in fermentative catalysis. co This paper gives a description of results of investigating the chemical mposition of polar components extracted from RASO. Concentrates of the Dobain process using tar oil of Arian crude [2] were selected for investigation [2]. * Neftekhimiya 21, No. 4, 625-629, 1981.