This document summarizes a study on the spectroscopic and micellization properties of uranyl hexanoate in organic solvents. Infrared spectroscopy revealed that uranyl hexanoate has partial ionic character, with the fatty acids existing in a dimeric state through hydrogen bonding. Conductometric measurements determined the critical micellar concentration of uranyl hexanoate in DMF to be 0.03M. The addition of Sudan dye increased conductivity but did not change the critical micellar concentration. Uranyl hexanoate behaved as a simple electrolyte below the critical micellar concentration.

1. ISSN (Print): 2328-3777, ISSN (Online): 2328-3785, ISSN (CD-ROM): 2328-3793
American International Journal of
Research in Formal, Applied
& Natural Sciences
AIJRFANS 14-264; © 2014, AIJRFANS All Rights Re Page 121
AIJRFANS is a refereed, indexed, peer-reviewed, multidisciplinary and open access journal published by
International Association of Scientific Innovation and Research (IASIR), USA
(An Association Unifying the Sciences, Engineering, and Applied Research)
Available online at http://www.iasir.net
Spectroscopic and Micellization of Uranyl Hexanoate in Organic
Solvent
Suman Kumaria
*, Mithlesh Shuklaa
, and R.K Shuklab
a
Department of Chemistry, Agra College, Agra-282004, India
b
Department of Chemistry, R.B.S. College, Agra-282004, India
*Email: vermasuman03@yahoo.co.in
Abstract:
I. Introduction
Surface active agents are characterized by the possession of both polar and non-polar regions in the same
molecule. This dual nature is responsible for the phenomenon of surface activity, and micellization and
solublization. The dual nature of a surfactant is typified by metal soaps or alkanoates, can be called
association colloids, indicating their tendency to associate in solution, forming particles of colloidal
dimensions.
Inspite of wide applications in many industries, the physico-chemical characteristics of rare earth
alkanoates have not been thoroughly investigated. Wu et al1
and Kanai2
developed new technologies to
synthesize metal alkanoates. Workers3-10
studied the spectroscopic and thermal behavior of metal
alkanoates. Sawada et al11
characterized the fine metal alkanoate particles by x-ray diffraction, differential
scanning calorimetery and specific surface area analysis. A number of workers12-24
studied their micellar
behavior using conductometric, ultrasonic, viscosity and density measurements.
In the present work, the results of FT-IR analysis have been used to obtain structural information of uranyl
hexanoate in solid state. Micellization behavior of uranyl hexanoate in DMF and effect of sudan dye have
been studied by conductometric investigations.
II. Experimental
All chemicals used were of BDH/AR grade. Solvent DMF was purified by distillation under reduced
pressure. Uranyl hexanoate was synthesized by direct metathesis of corresponding potassium alkanoates as
mentioned in our earlier publications12-13
. The insoluble deep yellow precipitate of uranyl hexanoate was
digested for 1-2 hour and separated from the mother liquor by filtering through a Buchner funnel under
reduced pressure and washed with water and then alcohol. The uranyl hexanoate thus obtained was dried in
an air oven at 50-60o
C and final drying of the alkanoate was carried out under reduced pressure. The purity
of uranyl hexanoate was checked by elemental analysis and the absence of hydroxylic group was confirmed
by FT-IR analysis.
The infrared absorption spectra of hexanoic acid and their corresponding uranyl hexanoate were recorded
with a Perkin-Elmer ‘Model 577’ grating spectrophotometer in the region 4000-200 cm-1
using the
potassium bromide disc method. A digital conductivity meter (Toshniwal CL 01.10A) and a dipping type
conductivity cell with platinized electrodes (cell constant 0.895) were used for measuring the conductance
of uranyl hexanoate solution at 40±0.05 o
C.
Abstract: Micellization behavior of uranyl hexanoate in non-aqueous solvent was studied by using
conductometric measurements. The critical micellar concentration (CMC), molar conductance and
degree of ionization have been determined. The molar conductance, of the solutions of uranyl hexanoate
decreases with increasing solute concentration. The decrease in molar conductance may be due to the
combined effects of ionic atmosphere, solvation of ions, decrease of mobility and ionization and
formation of micelles. The results show that the uranyl hexanoate behaves as a simple electrolyte in non-
aqueous solvent below the CMC and the addition of Sudan dye increases the specific conductance of the
alkanoates solution but the general behavior of the solution remains unaltered. The physico-chemical
characteristics of uranyl hexanoate in solid state were investigated by FT-IR analysis. The IR results
revealed that the fatty acids exist in dimeric state through hydrogen bonding and uranyl hexanoate
possess partial ionic character.
Key words: Uranyl hexanoate, Sudan dye, critical micellar concentration, Specific conductance, molar
conductance, degree of ionization.

2. Suman Kumari et al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp.
121-125
AIJRFANS 14-264; © 2014, AIJRFANS All Rights Re Page 122
III. Results and Discussion
Infrared spectra
The infrared spectra of uranyl hexanoate shows marked differences with the spectrum of their
corresponding hexanoic acid in some spectral regions. In the spectra of uranyl hexanoate characteristics vO-
H stretch (2650-2660cm-1
), vC=O (1690-1700 cm-1
), vC-O+O-H (1468-1470cm-1
) stretch+ in plane deformation
and vO-H out of plane deformation (930-950cm-1
) vibrations of free acids which are characteristic bands of
dimeric carboxylic acids were found completely absent with the absorption maxima near 690cm-1
and
550cm-1
associated with carboxyl group bending and wagging modes. Beside it, two absorption bands are
observed near 1480cm-1
and 1370cm-1
corresponding to asymmetric and symmetric vibration of
carboxylate ion as pointed out by Duval, Lecomte and Douville10
with metal- oxygen bond near 435 cm-1
.
In uranyl hexanoate stretching frequencies of the UO2
2+
entity were also observed near 810 and 740 cm-1
.
Specific conductance, k (mhos cm-1
) and CMC
The specific conductance, k (mhos cm-1
) clearly depends on the concentration of the alkanoate. The
Specific conductance, k of the dilute solutions of uranyl hexanoate in DMF increases with increasing solute
concentration, C (mol dm-3
). The increase in the specific conductance, k with the increase in solute
concentration may be due to the ionization of uranyl hexanoate into simple metal cations, UO2
++
and fatty
acids anions, C5H11COO-
in dilute solutions and the formation of micelles at higher concentrations of
alkanoate. The values of critical micellar concentration, CMC (0.03M) of the uranyl hexanoate. have been
determined by k-C plot (Fig.1). The concentration at which micelles formation starts known as critical
micellar concentration (CMC), beyond this concentration the bulk properties of the surfactant, such as
osmotic pressure, turbidity, solublization, surface tension, viscosity, ultrasonic velocity and conductivity
changes abruptly. If the micelles are formed in organic medium the aggregates are called “reversed
micelles” in this case the polar head groups of the surfactant are oriented in the interior and the lyophilic
groups extended outwards in to the solvent. It is suggested that the uranyl hexanoate is considerably ionized
in dilute solutions and the anions begin to aggregate to form micelles.
The addition of a surface active agent, i.e., sudan dye has no effect on the CMC value of uranyl hexanoate
as apparent from the plot k-C (Fig.1). When the concentration of dye is increased from 10-4
M to 10-2
M, the
specific conductance, k (mhos cm-1
) increases but CMC remains unchanged (Fig.2).
0
0.2
0.4
0.6
0.8
Specificconductancex103
(mhos)
Concenteration (mol dm -3)
Fig. 1 Specific Conductance vs. Concenteration of Uranyl Hexanoate at
40±0.05℃
Uranyl hexanoate in DMF
Uranyl hexanoate in DMF and Red
Sudan
0
0.2
0.4
0.6
0.8
1
Specificconductancex103
(mhos)
Concenteration ( mol dm -3)
Fig. 2 Specific Conductance vs. Concenteration of Uranyl Hexanoate at
40±0.05℃
Uranyl hexanoate in DMF and
Suan Red (Con 10-2)
Uranyl hexanoate in DMF and
Red Sudan( Conc 10-4)

3. Suman Kumari et al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp.
121-125
AIJRFANS 14-264; © 2014, AIJRFANS All Rights Re Page 123
The molar conductance, Λ (cm2
mol-1
) and ionization constant ,
The molar conductance, Λ of the solutions of uranyl hexanoate decreases with increasing solute
concentration. The decrease in molar conductance may be due to the combined effects of ionic atmosphere,
solvation of ions, decrease of mobility and ionization and formation of micelles. Since the molar
conductance, Λ of the solutions of uranyl hexanoate solution does not vary linearly with the square root of
alkanoate concentration, the Debye-Huckel-Onsager’s equation25
is not applicable to these solutions. Molar
conductance results show that solution of uranyl hexanoate behaves as simple electrolyte and ionization of
uranyl hexanoate solution may be explained by Ostwald’s manner.
If C (mol dm-3
) is the concentration and α is the degree of ionization of uranyl hexanoate solution, molar
concentration may be represented as follows:
(C5H11COO)2UO2 UO2
++
+ 2 C5H11COO-
C(1- α) C α 2C
The ionization constant, , for this equilibrium may be expressed as follows:
α α
The ionic concentrations are low in dilute solutions, so interionic effects are almost negligible. Therefore,
the solution of alkanoate does not deviate appreciably from ideal behavior and the activities of ions can be
taken as almost equal to the concentrations. The degree of ionization, α may be replaced by the
conductance ratio, Λ Λ where Λ and Λ (cm2
mol-1
) are the molar conductance at finite and infinite
dilution, respectively. By substituting the value of α and rearranging, equation (1) can be written as:
Λ
Λ
Λ
Λ
The values of ionization constant, , and limiting molar conductance, Λ were obtained from the
slope, Λ Λ and intercept Λ of the linear part of the plot (Fig.3) of Λ below
critical micellar concentration. The value of limiting molar conductance, Λ was found to be 35.0.
The values of degree of ionization, α have been evaluated by assuming α as equal to the conductance ratio,
Λ Λ . The values of the degree of ionization lie between 0.513 and 0.802 (Table I), thereby confirming the
fact that the uranyl hexanoate behaves as a simple electrolyte. The degree of ionization decreases rapidly in
dilute solutions with the increase in uranyl hexanoate concentration (Table. I).
It may thus conclude that the addition of Sudan dye increases the specific conductance, k (mhos cm-1
) of
the alkanoate solution (Table I and II) but the general behavior of the alkanoate remains unaltered.
0
10
20
30
40
50
60
70
80
90
100
3.47
3.48
3.57
3.64
3.68
3.74
3.79
3.83
3.95
3.96
4.04
4.15
4.27
4.33
4.47
4.67
4.96
5.2
Ʌ2C2x102
1/Tx 102
Fig.3 Ʌ2C2 vs. 1/T
Uranyl hexanoate in DMF

4. Suman Kumari et al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp.
121-125
AIJRFANS 14-264; © 2014, AIJRFANS All Rights Re Page 124
Table I: Conductance of uranyl hexanoate in DMF at 40±0.05o
C
Concenteration,
C (mol dm-3
)
Specific Condctance, k
(mhos cm-1
)
Molar
Conductance,
Λ (cm2
mol-1
)
2
C2
×102
1/ ×102
Degree of
Ionization, α
0.0100 0.301 30.10 09.06 2.53 0.798
0.0108 0.320 29.62 10.24 3.37 0.791
0.0119 0.342 28.74 11.69 3.48 0.743
0.0131 0.359 27.40 12.88 3.64 0.732
0.0147 0.393 26.73 15.44 3.74 0.714
0.0166 0.433 26.08 17.33 3.83 0.697
0.0192 0.484 25.21 23.42 3.96 0.674
0.0227 0.547 24.09 29.90 4.15 0.644
0.0277 0.640 23.10 40.94 4.33 0.617
0.0357 0.765 21.43 58.47 4.67 0.572
0.0500 0.960 19.20 92.16 5.20 0.513
Table II: Conductance of uranyl hexanoate in Sudan dye (Conc. 10-4
) and Sudan Red (Conc. 10-2
) in
DMF at 40±0.05o
C
(Conc. 10-4
) (Conc. 10-2
)
Concenteration,
C(mol dm-3
)
Specific Condctance
k×103
Specific Condctance k×103
0.0100 0.202 0.327
0.0108 0.217 0.352
0.0119 0.234 0.377
0.0131 0.254 0.410
0.0147 0.277 0.443
0.0166 0.300 0.490
0.0192 0.346 0.562
0.0227 0.389 0.664
0.0277 0.452 0.675
0.0357 0.544 0.975
0.0500 0.635 1.140
Acknowledgements
The authors are thankful to UGC, New Delhi for the financial assistance.
References
[1]. Maoying Wu, Chesmin Xiao (Department of Chemical Engineering, Guangdong University of Industry, Canton, Peop.
Rep. China. 510090) Riyong Huaxue Gongye, 5, 19-21 (1998) (ch) Qinggongyebu Kexue Jishu Qingbao yanjiuso.
[2]. Hiroyuki Kanai (Shinko K.K., Japan) Jpn. Kokai Tokkyo Koho JP. 11 349, 980 (99 349, 980) (Cl. C 11 B13/00), 21 Dec
1999, Appl. 1998/ 175, 435, 8 Jun 1998; 4 pp. (Japan).
[3]. Da-Guang (Dept. of Chemical Engineering, GDUT, Canton, Peop. Rep. China (510090). Guangdong Gongye Daxue
Xuebao 16(3), 109-113(1999) (ch), Guangdong Gongye Daxue.
[4]. K.N. Mehrotra, R.K. Shukla, M. Chauhan, Tenside Sur. Det. 34(2), 124 (1997).
[5]. Marie-Claude Corbeil, Laurianne Robinet, (Analytical Research Laboratory, Canadian Conservation Institute, Department
of Canadian Heritage, Ottawa, ON Can. K1A OM 5), Powder Diffraction, American Institute of Physics 17(1), 52-60
(2002).
[6]. Zein E. Shoeb, Sayed. M. Hammad, A.A Yousef, (National research centre cairo Egypt ). Grasas Aceites (sevilla) Instituto
de lama Grasa. 50(6), 426-434 (1999).
[7]. J. B. Peng, G. T. Barnes, I. R. Gentle, G. J. Foran, J. Phys. Chem. 104(23), 5553-5556 B(2000), (Eng).
[8]. M. F. R. Fouda, Elham A.A Yousef, S. S. Mohamed, Itate Zein E. Shoeb, ( Inog. Chemistry Deptt. National research
centre cairo Egypt ). Grasas Aceites (sevilla, Spain) Instituto de lama Grasa. 52(5), 317-322 (2001).
[9]. Mei-juan Lin, Wengong Zhang, Xiamon Huang, (Inst. Polymer Sci., Fujian Normal univ., Fuzhou, Peop. Rep. China).
Xiandai Suliao Jiagong Yingyong, Zhongguo Shihua Jituan Gongsi Xiandai Suliao Jiagong Yingyong Qingbao
Zhongxinzhan 13(4), 43-45 (2001) (Ch).
[10]. C. Duval, J. Lecomte, F. Douville, Ann. Phys. 17, 5 (1942).
[11]. Kouhei Sawada, Miki Konaka (Oleochemicals Research Laboratory, NOF Corporation, Hyogo, Japan 660-0095) Journal
of Oleoscience, Japan Oil Chemist’s Society.53(12), 627-640 (2004) (Eng).
[12]. M. Shukla, S. Kumari, R.K. Shukla, Effect of chain length on acoustic behavior of gadolinium alkanoates in mixed organic
solvents. Acta Acustica. 96, 63 (2010)
[13]. M. Shukla, S. Kumari, R.K. Shukla, J. Dispersion science and technology, 32, 1 (2011).
[14]. K.N. Mehrotra, M. Chauhan, R.K. Shukla, J. Appl. Poly. Sci. 55, 431 (1995).

5. Suman Kumari et al., American International Journal of Research in Formal, Applied & Natural Sciences, 6(2), March-May 2014, pp.
121-125
AIJRFANS 14-264; © 2014, AIJRFANS All Rights Re Page 125
[15]. K.N. Mehrotra, R.K. Shukla, Mithlesh Chauhan, Tenside Sur. Det. 29(6), 432 (1992).
[16]. K.N. Mehrotra, R.K. Shukla, M. Chauhan, J. Appl. Poly. Sci. 39, 1745 (1990).
[17]. K.N. Mehrotra, R.K. Shukla, Mithlesh Chauhan, Monatshefte für Chemie (Austria) 121, 461 (1990).
[18]. K.N. Mehrotra, R.K. Shukla, Mithlesh Chauhan, J. Electrochem. Soc. India. 14(39), 147 (1990).
[19]. K.N. Mehrotra, R.K. Shukla, M. Chauhan, J. Am. Oil Chemists Soc. 67(7), 446 (1990).
[20]. K.N. Mehrotra, R.K. Shukla, M. Chauhan, J. Phys. Chem. Liq. 21, 237 (1990).
[21]. K.N. Mehrotra, R.K. Shukla, M. Chauhan, J. Colloid and Surfaces, 119, 67 (1996).
[22]. R. K. Shukla, M. Shukla, Vikas Mishra, Physics and Chemistry of Liquids 43(3), 345-349(2007).
[23]. K.N. Mehrotra, R.K. Shukla, M. Chauhan, J. Phys. Chem. Liq. 25, 7 (1992).
[24]. K.N. Mehrotra, M. Anis, Tenside Surf. Det 38(2), 116-119(2001).
[25]. I. N. Levine, Physical Chemistry, Fourth Edition, New York: McGraw-Hill Inc (1995).