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C A T A L Y T I C A L K Y L A T I O N OF T E T R A L I N
COMMUNICATION 7. ALKYLATION OF TETRALIN WITH ALKYL HALIDES
IN PRESENCE OF METALLIC ALUMINUM
N. I . S h u i k i n , N . A . P o z d n y a k , a n d I . N . L i f a n o v a
N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences, USSR Translated from Izvestiya Akademii Nauk SSSR, Otdelenie Khimicheskikh Nauk, No. 4, pp. 695-697, April, 196~ Original article submitted October 28, 1961
A ccording to the literature, the alkylation of aromatic hydrocarbons with alkyl halides in presence of metall ic aluminum begins at the boiling point of the mixture [1-3]. Sidorova and Tsukervanik [4] consider that to start the reaction the mixture must be heated to 70-80 ~ ; at this temperature the aluminum dissolves and hydrogen halide is liberated. We have previously carried out the alkylation of tetralin with butyl bromide [5] at the boiling point of the mixture (12T). Once begun, reaction went very vigorously, often with a sharp rise in temperature; it was then accompanied by side processes: opening of the hydrogenated ring in tetralin and cyclizat ion of the butyltetralin formed to anthracene. In the present work we carried out the alkylation with normal propyl, butyl, heptyl, nonyl, and decyl bromides. I t was shown that the alkylatinn of tetratin in preseime of aluminum may proceed already at room temperature (23 ~ when it i~ carried out in an atmosphere of nitrogen
i- [IBr ~ - - ~ - - R "-.v./ ' . .~ 23 -65 ~ N~
At 65 ~ the yields of propyl-, butyl- , heptyl- , nonyl- , and decyl-tetralins were 75.6, 92.5, 98.8, 77.3, and 53.b~0 respectively. Control experiments carried out in air showed that at 65 ~ even after six hours' stirring, the alkylation of tetralin with butyl and heptyl bromides had not started. At 105 ~ we obtained butyltetralin in 84% yield, In the alkylation of benzene in presence of alumiJmm Dolgov and Bnatov [6] observed the complete isemerization of the primary groups into secondary and tertiary. In our work it was shown that at 65 ~ only partial isomerization of pri- mary alkyl groups occurs, and at 23 ~ in alkylation with propyl and butyl bromides alkyltetratins are formed contain- tag a normal alkyl group.
E X P E R I M E N T A L Freshly prepared aluminum fillings (0.0~3-0.05 g -a tom per mole of alkyI halide taken) were placed in a
carefully dried flask from which air was displaced by the passage of nitrogen for 30 minutes. The fillings were heated at 40 ~ in the nitrogen atmosphere, and then 0.25 mole of tetralin, 0.25 or 0.125 mole of the alkyl bromide, and, when the experiments were carried out in a solvent, 60 ml of nonane were introduced (Table 1), The mixture was heated at the required temperature of five hours with constant passage of nitrogen. The reaction mixture was de- composed with water, acidified with hydrochloric acid, washed, and dried; it was then vacuum-disti l led through a column of 15-plate efficiency. Unchanged tetralin and alkyl bromide first distilled off, and then mono- and di- alkyltetralins. The results of the experiments are given in Table 1. It will be seen that the optimum conditions for the alkylation of tetralin with alkyl bromides are" temperature 65 ~ arid the performance of the experiments in an atmosphere of nitrogen and in a nonane medium for five hours. Under these conditions reaction began after 10- 40 minutes of stirring. The yields of propyl- , butyl- , heptyl- , nonyl- , and decyl-tetralins (calculated on the amount of bromo compound) were, respectively- 75.6, 92.5, 98.8. 77.3, and 53.5%.
The relation of the yield of alkyltetralin to the chain length of the alkyl bromide is shown for experiments car- ried out at 23 ~ and 65 ~ (figure), From the figure(Curve 1) will be seen that at 65 ~ heptyl bromide reacts almost completely with tetralin with formation of heptyltetralin. The reduction in the yield of alkyltetralin with increase in the length of the carbon chain of the alkyl bromide occurs because of reduction in the reaction rate. This relation can be seen par- ticularly clearly from the experiments carried out at room temperature (23~ fl~ nonane solution reaction with propyl
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TABLE 1. Alkylation of Tetmlin with Alkyl Halides in Presence of Aluminum
Temp. Molar proportions Yield of monoalkyltettalin (%) of expt. tetralin: bromide: calculated on ] calculated on ~ : A1 tetralin [ bromide
65 23 23
105 65 23 23
105 65 23
105 65 23
105 65 23
105
1: 1:0.05 3: 4:0.05 1: 1:0.05
1: 1:0.05 1: 1:0.05 1: 1:0.05 h 1:0.05
2: 1:0.05 2: 1:0.05 1: 1:0.05
2: 1:0.05 2: 1:0.05 1: 1:0.05
2: 1:0.05 2: 1:0.05 1: 1:0.05 1: 1:0.023
Alkylation with propyl bromide
75.6 75.6 41.4 32ol 32.2 32.2
Alkylation with butyl bromide
34.0 34~ 92.5 92.5 34.0 34.0 16.0 16.0
Alkylation with heptyl bromide
35.1 ] 70.3 49.3 1 98.8 38o7 38.7
Alkylation with nonyl bromide
40.1 80.5 38.6 77.3 21,7 21.7
Alkylation with decyl bromide
39.6 79.2 24.6 53.0 14.1 14.1 41.1 41ol
Yield of dialkyl~ tetralin
3.0 6.5 0.5
2.0
4.5
5
5 0.5 5.0
3.0 4.5 1
10
Notes
I n n o n a f i e
In nonane
in nonane
In nonane
In nonane
In n o n a n e
In nonane
In nonane
In nonane
In nonane
In nonane
Yield, %
80
4 8 ,f I0
Figure. Relation of yield of alkyltetralin to length of chain of alkyl bromide: 1) experi- ments at 65* in nonane solution; 2) experi- ments at 23* without solvent; 3) experi- ments at 23* in nonane solution.
bromide began after ten minutes from the time of mixing, that with butyl bromide after 20 minutes, and with heptyl bromide reaction did not begin even after stirring for four hours. In absence of solvent propyl and butyl bromides reacted Lmme- diately after the mixing of the components. Reaction with heptyl bromide began after two hours, that with nonyl bromide after 4.5 hours, and that with decyt bromide after seven hours. At 23* the alkylation of tetralin with propyl and butyl bromides was complete after five hours and that with heptyl, nonyl, and decyl bromides after 125 hours of stirring. The end of the re- action was indicated by the cessation of hydrogen bromide liber- ation. Despite the long duration of the experiments, the yields of nonyl- and decyl-tetralins were considerably lower than those of propyl-, butyl-, and heptyl-tetralins (see Table 1). By the analysis of the alkyltetralins obtained With the aid of the infrared spectra it was shown that at 65* and 105 ~ 6-mono- and 6,7-di-alkyltetralins of normal and branched structure were formed. In alkylation with propyl and butyl bromides at 23*
6-alkyltetralins containing a normal alkyl group were formed (Table 2).
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TABLE 2. Properties of A!kyltetralins and Results of Their Spectrographic Investigation
& . B.p. at n~ I .. ~. ~ Proposed structural formula reduced ~' ~ O ~ 1 e, i ~ ) ~ p.ressure ] ~ ~ ~ = ~ (*c) z . z o ~
Alkylation with propyl bromide
/ 65 1t0--118 (6) I ,5262 286 5 148 :1,5 I / - -C--C Ir R- -C- -C- -C 23 110--lt3 (5) 1,5263 t296 I 6 88 :1,0 I / - -C--C--C 23 1 t0--1 t5 (5) ] ,52631298 6 100 t ,0 R- -C- -C- -C
Alkylation with butyl bromide
I I 1 c
r23-- [ 1 / (;5 f28 (5) 1,5237 300 6 3.~ 1,4 I /--C--C=-C ,~ R - - C - - C - - C - - C 2:~ il25--128 (5) 1,52~5 433 7 138 t ,2 R--C--C-LC--C
Alkylation with heptyl bromide
65 167--170 (6) 1,5150 520 9 139 - 1,4 . I /--C--(C)4--C ~ R--C--(C)5--C
Alkylation with nonyl bromide
23 190--195 (5) 1,5095 685 11 ~152 :l,5 R--C--(C)~--C n I/--C--(C)7--C 23 195--197 (5) ]1,5120 805 12 68 { t ,0 R--C--(CbC
Alkylation with decyl bromide
~05 la~- /95(6) 70s ~1 t3t ~,5 R--C'--(C)s--C H 23 185-t95 (6) ~,,~0~0 7oo ~2s I,,~
"* ~, = intensity of absorption bands for CH~ groups in region of 2930 cm '* . ~ = intensity of absorption bands for CH s groups in region of 2960 cm "1.
S U M M A R Y 1. In the alkylation of tetralin with normal pyropyl, butyl, heptyl, nonyl, and decyl bromides in presence of
a luminum at 23", 65*~ and 105" the corresponding propyl- , butyl - , hepty l - , nonyl- , and decyl- tetral ins are formed in yields of 53-99~
2. Conditions were found under which the alkylation of tetralin proceeds without the isomerization of the sub-
stituents.
LITERATURE CITED I. V.D. Azatyan, Dokl. AN SSSR 5.9, 901 (1948). 2. M. 13. Turova-Polyak and N. P. Dobrosr Zh. obshch, khimii 2__99, 1072 (1959). 3. B.N. Dolgov and S. A. Bnatov, Zh. obshch, khimii 2_99, 582 (1959). 4. N.G. Sidorova, I. P. Tsukervanik and Z. Kh. Avidova, Dokl. AN Uz. SSSR 5, 53 (1953). 5. N.I. Shuikin, B. L. Lebedev, and N. A. Pozdnyak, Neftekhimiya I, 39 (1961). 6. B.N. Dolgov and S. A. Bnatov, Izv. vysshikh uch. zavedenii_5,714 (1959).
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