1454
VERETENNIKOV et al.
nitric acid as was observed for nitration of nitrobenz-
ene isomers in sulfuric acid medium [4].
content of mono- and dinitrochlorobenzene isomers.
The effective constants of pseudofirst order were
calculated by the formula:
The data in Table 1 indicate that in nitrochloro-
benzene nitration the experimental value of activation
energy E only slightly decreases with growing con-
centration of nitric acid; apparently the activation
energy is weakly affected by H of the process of
nitronium cation formation along reaction (1).
(c c0)
k
=
1 ln
,
(c c )
where
c0,
c ,
c
is
dichlorobenzene
1
concentration, mol l at the start of reaction, at the
moment of measurement, and at the end of the experi-
ment respectively.
The comparison of keff values for mono- and di-
nitration of chlorobenzene shows that introduction of
a nitro group in the para-position with respect to
chlorine results in 1600 times reaction rate decrease,
REFERENCES
whereas in homogeneous nitration in sulfuric acid
di
eff
medium the ratio kemffono/k
equals 135 [9]. Presum-
1. Orlova, E.Yu., Khimiya i tekhnologiya brizantnykh
vzryvchatykh veshchestv (Chemistry and Technology of
High Explosive), Leningrad: Khimiya, 1973.
2. Martinsen, H., Z. Physik. Chem., 1907, vol. 59,
pp. 605 612; Bennett, G.M., J. Chem. Soc., 1947,
no. 3, pp. 774 781; Bogachev, Yu.S., Shapet,ko, N.N.,
Gorelik, M.V., Andrievskii, Yu.S., Avidon, S.V.,
Kisin, A.V., and Kuznetsova, M.G., Zh. Obshch.
Khim., 1993, vol. 63, no. 4, pp. 1214 1221; Grabov-
skaya, Zh.E and Vinnik, M.I., Zh. Fiz. Khim., 1966,
vol. 40, no. 7, pp. 2272 2276.
ably this difference is due to lower activity and con-
sequently higher selectivity of the nitrating agent in
the aqueous nitric acid [3].
EXPERIMENTAL
The procedure for preparation of nitric acid water
solutions was described in [4].
We used p-nitrochlorobenzene of mp 83.5 C,
2,4-dinitrochlorobenzene of mp 51.0 C from ethanol).
3. Vinnik, M.I., Grabovskaya, Zh.E., and Arzamasko-
va, L.N., Zh. Fiz. Khim., 1967, vol. 41, no. 4,
pp. 1102 1111.
The nitration kinetics was studied by means of
GLC on a gas chromatograph Tsvet-500M by measur-
ing 2,4-dinitrochlorobenzene accumulation under
conditions of pseudofirst order at 20-fold molar
excess of nitric acid. The stationary phase used was
XE-60 (5%) on Chromaton-N-AW-DMC with
particle size 0.325 0.400 nm. Carrier gas helium,
detector katharometer, detector temperature 360 C,
oven temperature programmed from 90 to 360 C.
4. Veretennikov, E.A., Lebedev, B.A., and Tselin-
skii, I.V., Zh. Org. Khim., 2001, vol. 37, no. 7,
pp. 1016 1020.
5. Emanuel,, N.M. and Knorre, D.G., Kurs khimicheskoi
kinetiki (Course of Chemical Kinetics), Moscow: Vys-
shaya shkola, 1984.
6. Draper, M.R. and Ridd, J.H., J. Chem. Soc., Perkin
Trans. II, 1981, no. 1, pp. 94 99.
7. Moodie, R.B., Schofield, K., and Taylor, P.G.,
J. Chem. Soc., Perkin Trans. II, 1979, no. 2,
pp. 133 139.
8. Belson, D.J. and Strachan, A.N., J. Chem. Soc., Per-
kin Trans. II, 1989, no. 1, pp. 15 21.
9. Coombes, R.G., Crout, D.H.G., Hogget, J.G.,
Moodie, R.B., and Schofield, K., J. Chem. Soc. B,
1970, no. 3, pp. 347 356.
The reaction was carried out in a flask kept at
constant temperature and equipped by stirrer, thermo-
meter, and sampling device. A weighed portion of
p-nitrochlorobenzene was charged to the flask at stir-
ring into the nitric acid of a given concentration. The
reaction progress was monitored by sampling.
Temperature in the course of reaction was controlled
within 0.1 C. The samples of the reaction mixture
were diluted with excess 2-propanol and analyzed for
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 10 2001