ISSN 0018ꢀ1439, High Energy Chemistry, 2010, Vol. 44, No. 6, pp. 498–502. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © L.N. Karyakina, A.V. Oleinik, 2010, published in Khimiya Vysokikh Energii, 2010, Vol. 44, No. 6, pp. 533–536.
PHOTOCHEMISTRY
Photolysis of paraꢀAzidobenzoic Acid in Solutions
and in the Crystalline State
L. N. Karyakina and A. V. Oleinik
Nizhni Novgorod State University, pr. Gagarina 23, Nizhni Novgorod, 603950 Russia
eꢀmail: photo@ichem.unn.ru
Received March 17, 2010
Abstract—Photolysis of paraꢀazidobenzoic acid (
at different pH values was studied by means of IR spectroscopy, electronic absorption spectroscopy, and TLC.
The nature of ꢀABA photolysis products is determined by the character of solvation or hydration of the acid
pꢀABA) in the crystalline state, organic solvents, and water
L
in solutions and the relative arrangement of azide molecules in the crystalline state or highly concentrated
solutions.
DOI: 10.1134/S001814391006007X
The wide use of aromatic azides in various areas of the region of 4000–400 cm–1 in the crystalline state
chemistry has required a knowledge of their photoꢀ and in benzene before and after irradiation. The elecꢀ
chemical properties. These properties depend upon tronic absorption spectra of pꢀABA and pꢀAmBA were
many factors, of which one is the presence and the measured with a Specord 40 spectrophotometer
position of substituents in the aromatic azide moleꢀ over the wavelength range of 220–500 nm. The phoꢀ
cule. In addition, an important role in the formation tolysis of
p
ꢀABA was conducted by irradiating ~5
×
⎯
5
of various photolysis products is played by the solvaꢀ 10 mol/l solutions in different solvents in quartz cells
tion or hydration of nitrenes produced in solutions having an optical path length of 1 cm with light from a
during the photodegradation of azides and by the assoꢀ DRKꢀ120 mercury lamp at a distance of 20 cm over 2,
ciation of aromatic azide molecules in highly concenꢀ 5, and 10 min.
trated solutions or in the crystalline state [1–5].
For the TLC analysis of the photolysis products,
–3
The objective of this work was to examine the influꢀ
p
ꢀABA was photolyzed in ~1
×
10 mol/l solutions
ence of the COOH group in the paraꢀposition on the through a fused silica wall at a distance of 10 cm over
nature and the yield of photodegradation products of 15 min with stirring.
the
p
ꢀABA azido group, since the photolysis of para
ꢀ
The photolysis products were separated by TLC on
azidobenzoic acid in various solvents and in the crysꢀ SORBFIL plates using a 5 : 2 (by volume) toluene–
talline state had not been studied.
methanol blend and were analyzed as described in [3].
The yield of the products was determined from the
areas of their spots on chromatograms,
EXPERIMENTAL
p
ꢀAzidobenzoic acid was synthesized by diazotizaꢀ
tion of paraꢀaminobenzoic acid ( ꢀAmBA) with a
hydrochloric acid solution of sodium nitrite at 0–5
RESULTS AND DISCUSSION
p
°
С
In the azidoꢀgroup vibration region of ~2100 and
–
1
and the subsequent reaction with sodium azide at 1300 cm , the IR spectra of
room temperature. The colorless
ꢀABA crystals curve ) display two characteristic absorption bands of
obtained were recrystallized from a hot petroleum the ꢀABA azido group corresponding to asymmetric
ether–benzene mixture (3 : 2 by volume). The eleꢀ stretching vibrations at 1210 cm and symmetric
mental analysis data for the organic azide are as folꢀ stretching vibrations at 1310 cm . The presence of
lows:
pꢀABA in nujol (figure,
p
1
p
–1
–1
these bands confirms the fact of formation of
from ꢀAmBA—the IR spectrum of ꢀAmBA is
shown in the figure (curve ).
For aromatic acids in the solid state, IR absorption
pꢀABA
p
p
3
Found, %:
C 51.56,
C 51.54,
H 3.07,
H 3.09,
N 25.85.
N 25.77.
–1
Calculated, %
at 2500–2700 cm due to hydroxyl groups is evidence
for the presence of dimers of the acids, wherein the
strongly hydrogenꢀbonded hydroxyl group gives as
The IR spectra of
p
ꢀABA and
p
ꢀAmBA were many as three bands in this region, although they are
recorded on a Specord IRꢀ75 spectrophotometer in weak [6, 7]. The stretching vibrations of the
pꢀABA
498