INDUCED BROMINATION OF AROMATIC HYDROCARBONS WITH ALKALI METAL BROMIDES 955
Table 2. Composition of isomers, partial rate factors f,
(2) Bromination is highly selective with respect to
monobromo derivatives in the para position of the ar-
omatic ring. With increasing molar content of ethyl-
and isopropylbenzenes, formed by the yield of bro-
mobenzene increases to 23% due to partial substitu-
tion of the alkyl groups with bromine atoms.
and the selectivity S of induced bromination of aromatic
f
compounds (293 K)
Isomer
Iso-
mer
ArBr
content,
wt %
f2
f4
Sf
REFERENCES
Me Ph Br
Et Ph Br
i-Pr Ph Br
2-
10.2
80.5
24.2
65.3
4.2
90.4
40.5
50.6
8.5
0.54
10.0 2.73
4
-
1. Yukel’son, I.I., Tekhnologiya osnovnogo organiches-
kogo sinteza (Technology of Basic Organic Synthesis),
Moscow: Khimiya, 1968.
. Lebedev, N.N., Khimiya i tekhnologiya osnovnogo i
neftekhimicheskogo sinteza (Chemistry and Technol-
ogy of Basic and Petrochemical Syntheses), Moscow:
Khimiya, 1975.
. Shamb, W., Setterfield, C., and Wentworth, L., Pere-
kis’ vodoroda (Hydrogen Peroxide) Moscow: Izd.
Inostr. Lit., 1958.
. Muganlinskii, F.F. and Guseinov, M.M., Zh. Vses.
Khim. O va im. D.I. Mendeleeva, 1985, vol. 30, no. 3,
pp. 340 345.
. Salakhov, M.S., Guseinov, M.M., Mamedov, Ya.N.,
et al., Zh. Prikl. Khim., 1978, vol. 41, no. 6,
pp. 1428 1430.
. USSR Inventor’s Certificate, no. 776033.
. Sadykhzade, S.I., Aliev, A.B., Mustafaev, R.I., and
Kuliev, L.G., Azerb. Khim. Zh., 1977, no. 5, pp. 42 47.
2-
0.895 14.7 3.1
0.023 11.2 3.4
4
-
2
2-
4
-
1.85*
1
,2-(Me) Ph Br
3-
22.8 1.1
2
4
-
3
4
5
EtO Ph Br
2-
0.143 10.7 2.18
4
-
78.6
*
Value corresponding to f .
3
and para positions for Me Ph, Et Ph, and i-Pr Ph
and in the meta and para positions for 1,2-(Me)2C H4
6
(Table 2). It can be seen that the partial rate factor
6
7
of induced bromination of methyl-, ethyl-, isopropyl-,
and ethoxybenzenes is 0.54, 0.895, 0.023, and 0.143
for the ortho ( f ) isomers and 10, 14.7, 11.2, and 10.7
for the para ( f ) isomers. In the case of 1,2-dimethyl-
benzene, the following results were obtained: 1.85
2
8. Salakhov, M.S., Guseinov, M.M., Chalabiev, Ch.A.,
and Abdullaev, D.K., Neftekhimiya, 1974, vol. 14,
no. 3, pp. 471 475.
4
for the meta ( f ) and 22.8 for para ( f ) isomers.
9. Salakhov, M.S., Guseinov, M.M., Chalabiev, Ch.A.,
and Abdullaev, D.K., Neftekhimiya, 1975, vol. 15,
no. 4, pp. 601 603.
3
4
These partial rate factors show that, in comparison
with benzene, the para positions of the above com-
pounds are activated to a greater extent than the ortho
and meta positions. For monosubstituted derivatives,
the reaction selectivity increases in the following or-
der EtO Ph < Me Ph < Et Ph < i-Pr Ph. Using the
known Brown Nelson equation [29], we determined
the relationship between the intra- and intermolecular
selectivities of aromatic compounds studied and found
that this system is characterized by an extremely low
intramolecular selectivity but a very high intermolec-
ular selectivity, i.e., it exhibits a high selectivity with
respect to the para position of the aromatic ring.
1
1
1
0. Salakhov, M.S., Guseinov, M.M., Chalabiev, Ch.A.,
and Abdullaev, D.K., Azerb. Neft. Khoz., 1975, no. 2,
pp. 61 62.
1. Salakhov, M.S., Guseinov, M.M., Chalabiev, Ch.A.,
and Mamedova, O.M., Zh. Prikl. Khim., 1980, vol. 53,
no. 5, pp. 1122 1125.
2. Salakhov, M.S., Guseinov, M.M., Chalabiev, Ch.A.,
and Mamedova, O.M., Azerb. Khim. Zh., 1984, vol. 53,
no. 5, pp. 69 72.
13. Samadumov, A. and Ostanina, V.A., Izv. Vyssh.
Uchebn. Zaved., Khim. Khim. Tekhnol., 1980, vol. 23,
no. 9, pp. 1079 1084.
1
4. Fedorishcheva, M.N., Ariko, N.G., and Mistke-
vich, N.M., Neftekhimiya, 1987, vol. 27, no. 6,
pp. 787 790.
CONCLUSIONS
1
5. Tmenov, D.I., Lysukho, T.V., and Shcherbina, F.F.,
(
1) Induced bromination of arenes with metal bro-
Neftekhimiya, 1977, vol. 17, no. 1, pp. 120 123.
mides in the presence of H O and HOCl proceeds
2
2
16. USSR Inventor’s Certificate, no. 1468896.
by the radical-ion mechanism that involved in situ
formed bromine and hypobromous acid, through sub-
stitution of a hydrogen atom in the benzene ring ex-
clusively.
1
1
7. USSR Inventor’s Certificate, no. 1768574.
8. Sadygov, O.A., Gurbanov, M.Sh., and Chalabi-
ev, Ch.A., Neftekhim., 1990, vol. 30, no. 1,
pp. 109 112.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 6 2006