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The alkylation of tetralins in the cycloparaffin ring by olefins
THE ALKYLATION OF TETRALINS IN THE CYCLOPARAFFIN RING BY OLEFINS L. K H . FP, EII)tA:N a n d N. M. NAZAI~OVA
"l'i~• N. I). Zelinskii Instit, ute of Organic ('hemistry of the U.S.S.H. Acmlc;my ~)t Seiml,es ( t?ec~,ired 2 l ..-1¢~g~,.eg1961)
THE alkylation of tetrMin with oleiins has been the object of a number of investigations. Catalysts which have been used are phosphoric [l], hydrofluoric [2], and sulphuric acids [3], aluminosilicate [3, 4], almninium chloride [3], and zinc chloride [4]. Depending on the activity of the catalyst, the reactioti~ has been carried out at room temperature and normal pressure or un(ter more severe conditions--at an elevated temperature (300 °) under pressure (60 atm). In tile presence of the catalysts mentioned, the olefin, as a rule. adds to the aromatic ring of the tetrMin in the 5 or 6 position. Under these conditions, the cycloparaffin ring of the tetra]in is not alkylated. The different behaviour in alkylation of the two condensed rings of the tetrMin molecule corresponds to the different behaviour of benzene and cyclohexane in this process. It is known that in the presence of acidic catalysts benzene readily reacts with olefins while unsubstituted cyclohexane does not react with them. Recently we succeeded in carrying out the alkylation of unsubstituted cyclohexane [5] and cyclopentane [6] with olefins at elevated temperatures under pressure. Under such conditions, benzene does not react with olefins. This fact accords with data in the literature on the thermal alkylation (450 °, 410 arm) of aliphatic-aromatic hydrocarbons--propylene and but-l-ene add not to the aromatic ring b u t to the side chain of Miphatic-aromatie hydrocarbons [7]. The observed difference in the behaviour of cyclohexane and benzene at elevated temperatures under pressure led to the assumption that under these conditions tetralin should be selectively alkylated b y olefins in the cycloparaffin ring. The results of experiments have confrmed this: on passing the substances through a quartz packing (450 °, 200 atm) tetrMin is alkylated by ethylene and propylene. Judging from the composition of the monoethyltetralin fraction, the molecule of the olefin adds to the tetralin in position 1. Results similar to ours have been obtained b y Closson et al. [8]: on alkylating tetrMin in the presence of' a b~sic catalyst--a-sodiotetralin (140 °, 49 a r m ) the ethylene added in position 1. * Neftekhimiya, 1: No. 5, 619-623. 196l. 525
526
KH. FREH)L1Nand N. M. NAZAROVA
EXPERIMENTAL PART The initial tetralin had: b.p. 78°/12 m m , d~° 0.9677, n 20 D 1.5440. The ethylene c o n t a i n e d 7 % of ethane, a n d the p r o p y l e n e 12% o f propane. The e x p e r i m e n t s were carried o u t in a continuous-flow a p p a r a t u s [5]. B r o k e n q u a r t z was used to fill the reactor, which h a d a v o l u m e of 120 ml. Tetralin was p u m p e d b y a liquid p u m p into a mixing vessel with a sight glass a n d stirrer. E t h y l e n e was passed in from a cylinder a n d dissolved in the tetralin with the stirrer working. The m i x t u r e of tetralin a n d ethylene was fed to the reactor t h r o u g h the lower valve of the mixer b y the same liquid p u m p . The feed o f t e t r a l i n - e t h y l e n e m i x t u r e was d e t e r m i n e d from its decrease in the mixing vessel. The reaction p r o d u c t s were subjected to rectification in a v a c u u m column (40 theoretical plates). Mono- a n d dialkyl tetralin fractions were isolated a n d were t h e n subjected to d e h y d r o g e n a t i o n at 300 ° over a P t / a c t i v a t e d carbon catalyst. A l k y l a t i o n with ethylene. The reaction o f tetralin with ethylene was studied at 400 a n d 450 ° a n d pressures of 50 a n d 200 arm. I t can be seen from Table l t h a t at 450 ° a n d a pressure of 200 a t m the ethylene t a k e n for the reaction (l 0 - 2 0 % b y weight in a d m i x t u r e with tetralin) was absorbed a h n o s t completeTABLE 1.
R E S U L T S OF : r i l e A L K Y L A T I O X OF T E T R A L I N W I T H E T I i Y L E N E
Experiments Conditions 2
:~
4
450 200 1.6 7 543 313
450 50 2.6 7 355 --
400 200 2.2 9 445 325
95
94
60
71
44
36
200
300
122
187
72
160
54
39
35
31
7-5 39.0 26.7 26.8
11.1 53.1 19.1 15.4
21.0 41.5
19"5 20"2 32"2 25"4
1
Temperature, °C Pressure, atm Molar ratio of tetralin to ethylene Rate of feed of the mixture, ml/min Yield of product, g Tetralin distilled off, g Degree of conversion of the ethylene, % by weight Degree of conversion of the tetralin, % by weight Yield of alkylate calculated on the ethylene taken, % by weight Yield of monoethyltetra]in, calculated on the ethylene taken, % by weight Yield of monoethyltetralin, calculated on the tetralin converted, % by weight Composition of the alkylate by fractions, % by weight 85-100°/12 mm 100-120°/12 rmn (monoethyltetra]in) 95-105°/4 mm (diethyltetralins) Residue
[
450 i 200 0"75 3 234 103
18
37.0
A l k y l a t i o n of tetralins b y olefins
527
ly. The main reaction product was monoethyltetralin. Thus, from the alkylate of experiment 2 (Table 1) on distillation, 53% of monoethyltetralin fraction and 19% of diethyltetralin fraction were isolated. When the temperature was reduced to 400 ° and the pressure to 50 atm, the degree of conversion of the ethylene and the yield of monoethyltetralin fraction diminished. The monoethyltetralin fractions from experiments 1 and 2 were combined and again distilled through the column. Two-thirds of the product distilled at 100.5°/12 mm and the bromine number was 4. After treatment with 80% sulphuric acid to remove contaminating unsaturated hydrocarbons, the
product isolated had: b.p.
237.5 2 3 8 . 5 ° / 7 5 0
ram,
n,1) 1-5359,
0.9566.
F o u n d , (~o: C 90.03; H 9-94. CrzH16. Calculated, °0: C 89.94; H 10.06.
[n order to determine the position of the lateral alkyl group, part of the monoethyltetralin was subjected to dehydrogenation on a Pt/activated carbon catalyst. The catalyzate obtained distilled at 251-253°/750 mm and had d~° 1.0003 and n~ 1-6008. The constants of the four monoethyltetralin isomers theoretically possible [9], the two isomeric ethylnaphthalenes [10, 11]. the monoethyltetralin isolated, and the ethylnaphthalene obtained from it after dehydrogenation are given in Table 2. The data of Table 2 show that TABLE 2, PROPERTIES OF Hydrocarbons .
.
.
.
.
.
.
Ethyltetralin*
ETtIYLTETRALINS
,
i B.p., C/ram !
.
.
.
.
.
.
.
.
.
.
ANI) ETtIYLNAPHTHALENES d 20
20
)t D
M.p. of the '~C picrate,
.
1-ethyltetra]in 2-ethyltetralin 5-ethyltetralin 6-ethyltetralin 1- e t h y l n a p h t h a l e n e 2-ethylnaphthalene
!237.5-238.5/750] mill 239"4 242"7 248'0 246'4 ] 258.67 ! 252
Ethylnaphthalene*
251-253/750mm i
0.9566 0.9530 i 0.9420 ! 0.9628 ! 0.9461 1.00816 0.9958 (at 15 ~=) 1.0003
1.5359 1.5319 1.5252 1.5399 1.5322 1.6062 1.6028 (at 15 °) 1.6008
98 76-77 99-5-100
* P r e p a r a t i o n o b t a i n e d b y the a u t h o r s of this paper.
the properties of the ethyltetralin obtained are close to those of 1-ethyltetralin. This is also confirmed b y the properties of the dehydrogenation product and the picrate obtained from it. The dehydrogenation product did not solidify even on cooling with dry ice, while 2-ethylnaphthalene has m.p. --7.5 ° [11]. A picrate with m.p. 99.5-100 ° was obtained fl'om the product of the dehydrogenation of the monoethyltetralin fraction. According to data in the literature [12], the m.p. of the picrate of 1-ethylnaphthalene is 98 ° and that of the picrate of 2-ethylnaphthalene 71 ° [13]. Analysis of the I R spectrum of mono-
528
KH. I,'REII)LIN and N. M. NAZAROVA
ethyltetralin taken in the 5-61a and 700-900 cm .~ regions showed its similarity to the spectrum of a benzene substituted in the 1 and 2 positions. The frequencies characteristic for a substituent in the 6 position were absent. The alkylate fractions with b.p. above 100.5°/12 mm were combined ~nd subjected t<> redistilla.ti<>n in a c<>hmm in vacuum. The following fractions were isolated:
Fraction
I
II
111
A m o u n t , inl B.1)., C/mn~
6.3 1()6 II 1/1()
12.~ I l l 113/10 1.5485
26'0 95'5-109/'3-5 ] .5319
Residu(, i
1/20 D
After treatment with 80% .H2804, fraction 267.5°/750 ram.
1II
14.5
had:
b.p. 266.3
F o u n d , °.0: (? 89.57; H 10.61. ('14H20. Calculated, o/./o. ('; 89-29: H 10.71.
Ascan be seen, the composition of fraction I I I corresponds to diethyltetralin. The isomers of this hydrocarbon have been little studied. According to data in the literature [8], 1,4-diethyltetralin has: b.p. 261 °, nb° 1.5262. Part of fraction I I I was subjected to dehydrogenation. The dehydrogenatiot~ product distilled at 278-280°/740 mm and had d~° 0.9964, n~° 1.5759. According to data in the literature [14], 1,4-diethylnaphthalene has: b.p. 136-139°/8 ram, d~° 0.9933, no° 1.6010. Alkylation with propylene. The experiment with propylene was carried out under the conditions which were the optimum conditions for the reactions with ethylene: at 450 °, an initial pressure of 200 arm, and a molar ratio of tetralin to propylene of 2.3. The degree of conversion of the propylene in one pass amounted to 51 ~o and that of the tetralin to 290/0. The yield of alkylate on the propylene taken for the reaction was 150°//o. 70.5 ml of alkylate on distillation yielded 25 ml of propyltetralin fraction (36% of the alky]ate) . ./152 . mill), . with b.p. 99°/5 mm (255.7-,56.7 n/io 1.5280, d~0 0.9436. The fraction isolated was subjected to dehydrogenation and the constants of the product obtained were determined. Table 3 gives the properties of the propyltetralins and propylnaphthalenes [11], and the properties of the propy]tetralin which we obtained and of the product of its dehydrogenation. It follows from the data of Table 3 that the properties of the fraction isolated are close to those of the propyltetralins. However, it is impossible to draw definite conclusions on the position and structure of the lateral carbon chain of the hydrocarbon obtained. B y analogy with the alkylation of cyclohexane
52,q
Alkylation of tetralins by olefins TABLE 3. PROPERTIES OF THE PROPYLTETRALINS AND PROPYLNAPHTKALENES •
Hydrocarbons
13.p., :C/ram
!
(t~o
20
~
.hi>
1-n-propylWtralin 1-isopropyltetralin 5-n-propyltetra]in 6-n-propyltetcalin 6-isopropyltetralin (15)
253 247 256 263 113 l l 5/8 =9
i).9395 0.9450
1.5308 1.5270
0-9400
Propyltetralin* 1-n-propylnaphthalene 2-n-propylnaphthalene 1-isopropylnaphtha len e
255.7 -256.7/752 272-6 273.5 265
2-isopr<>pylnaph t halene Propylnaphthalene*
268 269-271/753
0.9436 (1.9995 0.9770 0.9907 (at 1 5 ) 0.9795 0.9845
1-5290 1.5250 (at 29 ° ) 1.5280 1.5725 1.5872 1.5728 1.5772 I-5S60
* PreI)aration o b t a i n e d by the a u t h o r s of this paper.
with propylene and that of tetralin with ethylene under similar condition~. it m a y be assumed that the reaction of tetralin with propylene leads to the. formation of l-n-prcrpyltetralin. The a]kylate also yielded a fl'action (10.7%) with b.p. 124-[28°/5 mn~ n~° 1.5260, d2°~40.9380, containing, probably,, di-n-propyltetralin. In conclusion the authors express their thanks to G. K. Gaivor(>nsk~ and I. N. Lifanova ibr recording the IR spectra. <>f 1-ethyltetralin. SUMMARY
1. It has been established that, under thermal conditions, tetralin i, selectively alkylated by ethylene in the cycloparaffin ring. 2. It has been shown that the main reaction product with ethylene i~l-ethyltetralin. 3. It has been found that alkylation with propylene takes place less readil ~han with ethylene. T r a n s l a t e d 57t B. J. HAZZAR.D
REFERENCES 1. V. N. I P A T I E F F , H. PINES and V. I. KOMAREVSKY, I n d u s t r . Engng. Chem. 28: 222, 1936 2. W. S. CALCOTT, I. M. T I N K E R N and V. W E I N M A Y R , J . Amer. Chenl. Soe. 61: 1010, 1939 3. W. M. K U T Z , I. E. NICKELS, I. L McCOVERN and B. B. CORSON, J. Amev. (?hem. Soe. 70: 4026, 1948
530
KH. FREIDLIN a n d N. M. NAZAROVA
4. N. I. S H U I K I N a n d N. A. P O Z D N Y A K , Izv. A k a d . N a u k SSSR, Otd. k h i m . n., No. 6, 1094, 1960 5. N. M. N A Z A R O V A a n d L. Kh. F R E I D L I N , Dokl. Aka.d. N a u k SSSH 37: No. 5. 1125, 1961 tl. L. K h . F R E I D L I N , N. M. N A Z A R O V A a n d Ye. F. LITVIN, i z v . A k a d . Nm~k SSSI~. Otd. k h i m , n., No. 6, 1146, 1961 7. H. P I N E S a n d C. N. P I L L A I , J . A m e r . Chem. Soc. 81: 3629, 1959 8. R. CLOSSON, J. NAPOLITANO, J. E C K E a n d A. K O L K A , J. Organ. Chem. 22: 646, 1957 9. C. M. S T A V E L E Y a n d T. C. SMITH, 3. Inst. Petrol. 42: No. 386, 55, 1956 10. G. F. H I N S H E R a n d P. H. W I S E , J . Amer. Chem. Soe. 76: 1747, 1954 11. G. LI~VY, C o m p t . r e n d . Aead. Sei. 192: 1397, 1931 12. J. C A R N E L L U T T I , Ber. dtsch, c h e m . (~es. 13: 1671, 1880. 13. O. B R U N E L , Ber. d t s e h , c h e m . Ges. 17: 1179, 1884 14. N. F R ( i S C H L a n d G. H A R L A S S , M o n a t s h . 59: 275, 1932 15. L. J. S M I T H a n d CHIEN PEN-LO, J . A m e r . Chem. See. 70: 2209j 1948
"l'i~• N. I). Zelinskii Instit, ute of Organic ('hemistry of the U.S.S.H. Acmlc;my ~)t Seiml,es ( t?ec~,ired 2 l ..-1¢~g~,.eg1961)
THE alkylation of tetrMin with oleiins has been the object of a number of investigations. Catalysts which have been used are phosphoric [l], hydrofluoric [2], and sulphuric acids [3], aluminosilicate [3, 4], almninium chloride [3], and zinc chloride [4]. Depending on the activity of the catalyst, the reactioti~ has been carried out at room temperature and normal pressure or un(ter more severe conditions--at an elevated temperature (300 °) under pressure (60 atm). In tile presence of the catalysts mentioned, the olefin, as a rule. adds to the aromatic ring of the tetrMin in the 5 or 6 position. Under these conditions, the cycloparaffin ring of the tetra]in is not alkylated. The different behaviour in alkylation of the two condensed rings of the tetrMin molecule corresponds to the different behaviour of benzene and cyclohexane in this process. It is known that in the presence of acidic catalysts benzene readily reacts with olefins while unsubstituted cyclohexane does not react with them. Recently we succeeded in carrying out the alkylation of unsubstituted cyclohexane [5] and cyclopentane [6] with olefins at elevated temperatures under pressure. Under such conditions, benzene does not react with olefins. This fact accords with data in the literature on the thermal alkylation (450 °, 410 arm) of aliphatic-aromatic hydrocarbons--propylene and but-l-ene add not to the aromatic ring b u t to the side chain of Miphatic-aromatie hydrocarbons [7]. The observed difference in the behaviour of cyclohexane and benzene at elevated temperatures under pressure led to the assumption that under these conditions tetralin should be selectively alkylated b y olefins in the cycloparaffin ring. The results of experiments have confrmed this: on passing the substances through a quartz packing (450 °, 200 atm) tetrMin is alkylated by ethylene and propylene. Judging from the composition of the monoethyltetralin fraction, the molecule of the olefin adds to the tetralin in position 1. Results similar to ours have been obtained b y Closson et al. [8]: on alkylating tetrMin in the presence of' a b~sic catalyst--a-sodiotetralin (140 °, 49 a r m ) the ethylene added in position 1. * Neftekhimiya, 1: No. 5, 619-623. 196l. 525
526
KH. FREH)L1Nand N. M. NAZAROVA
EXPERIMENTAL PART The initial tetralin had: b.p. 78°/12 m m , d~° 0.9677, n 20 D 1.5440. The ethylene c o n t a i n e d 7 % of ethane, a n d the p r o p y l e n e 12% o f propane. The e x p e r i m e n t s were carried o u t in a continuous-flow a p p a r a t u s [5]. B r o k e n q u a r t z was used to fill the reactor, which h a d a v o l u m e of 120 ml. Tetralin was p u m p e d b y a liquid p u m p into a mixing vessel with a sight glass a n d stirrer. E t h y l e n e was passed in from a cylinder a n d dissolved in the tetralin with the stirrer working. The m i x t u r e of tetralin a n d ethylene was fed to the reactor t h r o u g h the lower valve of the mixer b y the same liquid p u m p . The feed o f t e t r a l i n - e t h y l e n e m i x t u r e was d e t e r m i n e d from its decrease in the mixing vessel. The reaction p r o d u c t s were subjected to rectification in a v a c u u m column (40 theoretical plates). Mono- a n d dialkyl tetralin fractions were isolated a n d were t h e n subjected to d e h y d r o g e n a t i o n at 300 ° over a P t / a c t i v a t e d carbon catalyst. A l k y l a t i o n with ethylene. The reaction o f tetralin with ethylene was studied at 400 a n d 450 ° a n d pressures of 50 a n d 200 arm. I t can be seen from Table l t h a t at 450 ° a n d a pressure of 200 a t m the ethylene t a k e n for the reaction (l 0 - 2 0 % b y weight in a d m i x t u r e with tetralin) was absorbed a h n o s t completeTABLE 1.
R E S U L T S OF : r i l e A L K Y L A T I O X OF T E T R A L I N W I T H E T I i Y L E N E
Experiments Conditions 2
:~
4
450 200 1.6 7 543 313
450 50 2.6 7 355 --
400 200 2.2 9 445 325
95
94
60
71
44
36
200
300
122
187
72
160
54
39
35
31
7-5 39.0 26.7 26.8
11.1 53.1 19.1 15.4
21.0 41.5
19"5 20"2 32"2 25"4
1
Temperature, °C Pressure, atm Molar ratio of tetralin to ethylene Rate of feed of the mixture, ml/min Yield of product, g Tetralin distilled off, g Degree of conversion of the ethylene, % by weight Degree of conversion of the tetralin, % by weight Yield of alkylate calculated on the ethylene taken, % by weight Yield of monoethyltetra]in, calculated on the ethylene taken, % by weight Yield of monoethyltetralin, calculated on the tetralin converted, % by weight Composition of the alkylate by fractions, % by weight 85-100°/12 mm 100-120°/12 rmn (monoethyltetra]in) 95-105°/4 mm (diethyltetralins) Residue
[
450 i 200 0"75 3 234 103
18
37.0
A l k y l a t i o n of tetralins b y olefins
527
ly. The main reaction product was monoethyltetralin. Thus, from the alkylate of experiment 2 (Table 1) on distillation, 53% of monoethyltetralin fraction and 19% of diethyltetralin fraction were isolated. When the temperature was reduced to 400 ° and the pressure to 50 atm, the degree of conversion of the ethylene and the yield of monoethyltetralin fraction diminished. The monoethyltetralin fractions from experiments 1 and 2 were combined and again distilled through the column. Two-thirds of the product distilled at 100.5°/12 mm and the bromine number was 4. After treatment with 80% sulphuric acid to remove contaminating unsaturated hydrocarbons, the
product isolated had: b.p.
237.5 2 3 8 . 5 ° / 7 5 0
ram,
n,1) 1-5359,
0.9566.
F o u n d , (~o: C 90.03; H 9-94. CrzH16. Calculated, °0: C 89.94; H 10.06.
[n order to determine the position of the lateral alkyl group, part of the monoethyltetralin was subjected to dehydrogenation on a Pt/activated carbon catalyst. The catalyzate obtained distilled at 251-253°/750 mm and had d~° 1.0003 and n~ 1-6008. The constants of the four monoethyltetralin isomers theoretically possible [9], the two isomeric ethylnaphthalenes [10, 11]. the monoethyltetralin isolated, and the ethylnaphthalene obtained from it after dehydrogenation are given in Table 2. The data of Table 2 show that TABLE 2, PROPERTIES OF Hydrocarbons .
.
.
.
.
.
.
Ethyltetralin*
ETtIYLTETRALINS
,
i B.p., C/ram !
.
.
.
.
.
.
.
.
.
.
ANI) ETtIYLNAPHTHALENES d 20
20
)t D
M.p. of the '~C picrate,
.
1-ethyltetra]in 2-ethyltetralin 5-ethyltetralin 6-ethyltetralin 1- e t h y l n a p h t h a l e n e 2-ethylnaphthalene
!237.5-238.5/750] mill 239"4 242"7 248'0 246'4 ] 258.67 ! 252
Ethylnaphthalene*
251-253/750mm i
0.9566 0.9530 i 0.9420 ! 0.9628 ! 0.9461 1.00816 0.9958 (at 15 ~=) 1.0003
1.5359 1.5319 1.5252 1.5399 1.5322 1.6062 1.6028 (at 15 °) 1.6008
98 76-77 99-5-100
* P r e p a r a t i o n o b t a i n e d b y the a u t h o r s of this paper.
the properties of the ethyltetralin obtained are close to those of 1-ethyltetralin. This is also confirmed b y the properties of the dehydrogenation product and the picrate obtained from it. The dehydrogenation product did not solidify even on cooling with dry ice, while 2-ethylnaphthalene has m.p. --7.5 ° [11]. A picrate with m.p. 99.5-100 ° was obtained fl'om the product of the dehydrogenation of the monoethyltetralin fraction. According to data in the literature [12], the m.p. of the picrate of 1-ethylnaphthalene is 98 ° and that of the picrate of 2-ethylnaphthalene 71 ° [13]. Analysis of the I R spectrum of mono-
528
KH. I,'REII)LIN and N. M. NAZAROVA
ethyltetralin taken in the 5-61a and 700-900 cm .~ regions showed its similarity to the spectrum of a benzene substituted in the 1 and 2 positions. The frequencies characteristic for a substituent in the 6 position were absent. The alkylate fractions with b.p. above 100.5°/12 mm were combined ~nd subjected t<> redistilla.ti<>n in a c<>hmm in vacuum. The following fractions were isolated:
Fraction
I
II
111
A m o u n t , inl B.1)., C/mn~
6.3 1()6 II 1/1()
12.~ I l l 113/10 1.5485
26'0 95'5-109/'3-5 ] .5319
Residu(, i
1/20 D
After treatment with 80% .H2804, fraction 267.5°/750 ram.
1II
14.5
had:
b.p. 266.3
F o u n d , °.0: (? 89.57; H 10.61. ('14H20. Calculated, o/./o. ('; 89-29: H 10.71.
Ascan be seen, the composition of fraction I I I corresponds to diethyltetralin. The isomers of this hydrocarbon have been little studied. According to data in the literature [8], 1,4-diethyltetralin has: b.p. 261 °, nb° 1.5262. Part of fraction I I I was subjected to dehydrogenation. The dehydrogenatiot~ product distilled at 278-280°/740 mm and had d~° 0.9964, n~° 1.5759. According to data in the literature [14], 1,4-diethylnaphthalene has: b.p. 136-139°/8 ram, d~° 0.9933, no° 1.6010. Alkylation with propylene. The experiment with propylene was carried out under the conditions which were the optimum conditions for the reactions with ethylene: at 450 °, an initial pressure of 200 arm, and a molar ratio of tetralin to propylene of 2.3. The degree of conversion of the propylene in one pass amounted to 51 ~o and that of the tetralin to 290/0. The yield of alkylate on the propylene taken for the reaction was 150°//o. 70.5 ml of alkylate on distillation yielded 25 ml of propyltetralin fraction (36% of the alky]ate) . ./152 . mill), . with b.p. 99°/5 mm (255.7-,56.7 n/io 1.5280, d~0 0.9436. The fraction isolated was subjected to dehydrogenation and the constants of the product obtained were determined. Table 3 gives the properties of the propyltetralins and propylnaphthalenes [11], and the properties of the propy]tetralin which we obtained and of the product of its dehydrogenation. It follows from the data of Table 3 that the properties of the fraction isolated are close to those of the propyltetralins. However, it is impossible to draw definite conclusions on the position and structure of the lateral carbon chain of the hydrocarbon obtained. B y analogy with the alkylation of cyclohexane
52,q
Alkylation of tetralins by olefins TABLE 3. PROPERTIES OF THE PROPYLTETRALINS AND PROPYLNAPHTKALENES •
Hydrocarbons
13.p., :C/ram
!
(t~o
20
~
.hi>
1-n-propylWtralin 1-isopropyltetralin 5-n-propyltetra]in 6-n-propyltetcalin 6-isopropyltetralin (15)
253 247 256 263 113 l l 5/8 =9
i).9395 0.9450
1.5308 1.5270
0-9400
Propyltetralin* 1-n-propylnaphthalene 2-n-propylnaphthalene 1-isopropylnaphtha len e
255.7 -256.7/752 272-6 273.5 265
2-isopr<>pylnaph t halene Propylnaphthalene*
268 269-271/753
0.9436 (1.9995 0.9770 0.9907 (at 1 5 ) 0.9795 0.9845
1-5290 1.5250 (at 29 ° ) 1.5280 1.5725 1.5872 1.5728 1.5772 I-5S60
* PreI)aration o b t a i n e d by the a u t h o r s of this paper.
with propylene and that of tetralin with ethylene under similar condition~. it m a y be assumed that the reaction of tetralin with propylene leads to the. formation of l-n-prcrpyltetralin. The a]kylate also yielded a fl'action (10.7%) with b.p. 124-[28°/5 mn~ n~° 1.5260, d2°~40.9380, containing, probably,, di-n-propyltetralin. In conclusion the authors express their thanks to G. K. Gaivor(>nsk~ and I. N. Lifanova ibr recording the IR spectra. <>f 1-ethyltetralin. SUMMARY
1. It has been established that, under thermal conditions, tetralin i, selectively alkylated by ethylene in the cycloparaffin ring. 2. It has been shown that the main reaction product with ethylene i~l-ethyltetralin. 3. It has been found that alkylation with propylene takes place less readil ~han with ethylene. T r a n s l a t e d 57t B. J. HAZZAR.D
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