Synthesis, characterization and crystal structure of (Z)-3-(4- chlorophenylamino)-1-Phenylbut-2-En-1-One

Article abstract of DOI:10.1007/s10870-012-0276-y

The title compound (Z)-3-(4-chlorophenylamino)- 1-phenylbut-2-en-1-one, has been prepared in good yield from the condensation reaction of benzoylacetone and 4-chloroaniline, catalyzed by two drops of formic acid. The compound was characterized by ¹H NMR, ¹³C NMR, IR spectroscopy, mass spectrometry, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and single crystal X-ray diffraction. The compound crystallized in the monoclinic crystal system with space group P21/n, Z = 4, V = 1370.3(7) A³, and unit cell parameters a = 6.4063(19) A, b = 7.085(2) A, c = 30.194(9) A, α = 90°, β = 90.824(5)° and γ = 90°. The crystal structure reveals that the compound exists in the enamino-ketone form and not the enol-imine form. Moreover, TGA/DSC analyses of the title compound was studied, showing two distinct endothermic peaks at temperatures of 134.05 and 302.71 °C, corresponding to melting and boiling points, respectively. Springer Science+Business Media, LLC 2012.

Full text of DOI:10.1007/s10870-012-0276-y

J Chem Crystallogr (2012) 42:543–548
DOI 10.1007/s10870-012-0276-y
ORIGINAL PAPER
Synthesis, Characterization and Crystal Structure
of (Z)-3-(4-Chlorophenylamino)-1-Phenylbut-2-En-1-One
•
Siddappa A. Patil Diego Gonzalez-Flores Phillip A. Medina
•
•
•
Seth Dever Michael Stentzel Joshua Popp Leslie W. Pineda
•
•
•
•
Mavis L. Montero Joseph W. Ziller Bradley D. Fahlman
•
Received: 25 September 2011 / Accepted: 17 January 2012 / Published online: 2 February 2012
Ó Springer Science+Business Media, LLC 2012
Abstract The title compound (Z)-3-(4-chlorophenylami-
no)-1-phenylbut-2-en-1-one, has been prepared in good
yield from the condensation reaction of benzoylacetone
and 4-chloroaniline, catalyzed by two drops of formic acid.
Keywords Synthesis Á Spectroscopy Á X-ray structure Á
(Z)-3-(4-chlorophenylamino)-1-phenylbut-2-en-1-one Á
Thermogravimetric analysis
1
The compound was characterized by H NMR, 13C NMR,
IR spectroscopy, mass spectrometry, elemental analysis,
thermogravimetric analysis (TGA), differential scanning
calorimetry (DSC), and single crystal X-ray diffraction.
The compound crystallized in the monoclinic crystal sys-
Introduction
The chelating tendencies of b-diketones have been exten-
sively studied because of their applications in pharmaceutical
compounds, biochemistry, biomedical research, immuno-
chemistry, and as precursors for the preparation of a large
number of heterocyclic compounds [1–3]. Previous studies of
some cyclizations involved the preparation of 4-methyl
aminopent-3-en-2-ones, 5-(1-methylethylaminomethylene)-
1,3-dioxane-4,6-diones and 5-(dimethylethylaminomethy-
lene)-2,2-dimethyl-1,3-dioxane-4,6-diones [4, 5]. The
anticonvulsant activities of various acyclic and cyclic ena-
minoketones have been studied in connection with their
lipophilicity, steric, electronic and hydrogen bonding effects
[6, 7]. The condensation products of acetylacetone/benzoy-
lacetone with various amines exist in three forms, viz. the
Schiff base, the ketamine and the enimine. The inter-
change between the ketamine and enimine tautomers involves
a small displacement in the equilibrium position of the acidic
proton.
3
˚
tem with space group P21/n, Z = 4, V = 1370.3(7) A , and
˚
unit cell parameters a = 6.4063(19) A, b = 7.085(2) A,
˚
˚
c = 30.194(9) A, a = 90°, b = 90.824(5)° and c = 90°.
The crystal structure reveals that the compound exists in
the enamino-ketone form and not the enol-imine form.
Moreover, TGA/DSC analyses of the title compound was
studied, showing two distinct endothermic peaks at tem-
peratures of 134.05 and 302.71 °C, corresponding to
melting and boiling points, respectively.
S. A. Patil Á B. D. Fahlman (&)
Department of Chemistry and Science of Advanced Materials
Program, Central Michigan University, Mount Pleasant,
MI 48859, USA
e-mail: fahlm1b@cmich.edu
D. Gonzalez-Flores Á L. W. Pineda Á M. L. Montero
Enaminones have been studied extensively, not only
because ofplentiful reactionchemistry, but alsoowing totheir
applications in coordination chemistry as well as chiral
auxiliaries in organic synthesis [8–12]. As part of an ongoing
investigation of the chemistry of enaminones, compound
(Z)-3-(4-chlorophenylamino)-1-phenylbut-2-en-1-one has
been synthesized by the condensation of benzoylacetone
and 4-chloroaniline, and its crystal structure has been
determined.
´
Centro de Electroquımica y Energıa Quımica (CELEQ) y
Escuela de Quımica, Universidad de Costa Rica, San Jose,
´
´
´
´
CR, USA
P. A. Medina Á S. Dever Á M. Stentzel Á J. Popp
Department of Chemistry, Central Michigan University,
Mount Pleasant, MI 48859, USA
J. W. Ziller
Department of Chemistry, University of California, Irvine,
CA 92697, USA
123

544
J Chem Crystallogr (2012) 42:543–548
Experimental Section
Crystals suitable for X-ray analysis were grown by the slow
evaporation method using methanol as the solvent at room
temperature. Compound was analyzed as C16H14ClNO
(calculated C 70.72, H 5.19, Cl 13.05, N 5.15%; found C
70.79, H 5.32, Cl 12.87, N 5.10%). 1H-NMR (CDCl3,
300 MHz) d: 2.13 (s, 3H, CH3), 5.91 (s, 1H, CH), 7.12–7.08
(m, 2H, ArH), 7.35–7.32 (m, 2H, ArH), 7.46–7.43 (m, 3H,
ArH), 7.92–7.89 (m, 2H, ArH), 13.07 (s, 1H, NH). 13C-
NMR (CDCl3, 75 MHz) d: 20.38 (CH3), 94.65 (CH),
125.89, 127.06, 128.30, 129.29, 131.06, 130.09 (ArC),
161.69 (C–NH), 188.95 (C=O). Mass data (TOF MS EI?):
calculated for C16H14ClNO [M?] 271.07, found: 271.07. IR
absorptions (KBr, cm-1): 3056 (w), 1618 (s), 1492 (m),
1444 (s), 1405 (m), 1378 (w), 1329 (s), 1289 (m), 1231 (m),
1198 (s), 1178 (m), 1156 (w), 1113 (m), 1093 (s), 1068
(m), 1029 (s), 1012 (s), 999 (m), 979 (m), 856 (m), 840 (s),
805 (m), 767 (s), 713 (s), 690 (s), 663 (m), 560 (m), 504 (s).
General Information on Reagents and Techniques
Reactions were carried out under aerobic conditions. All
reagents and solvents are of analytical grade; they were pur-
chased and used without further purification. Benzoylacetone,
4-chlororlaniline and formic acid were procured commercially
from Sigma-Aldrich, and were used without further purifica-
tion. Nuclear magnetic resonance (NMR) spectra were
obtained using a 10 to 25% solution in deuterochloroform
(CDCl3). 1H and 13C NMR spectra were recorded on a Varian
Mercury 300 MHz spectrometer. Proton and carbon chemical
shifts are reported in parts-per-million (d) with respect to tet-
ramethylsilane (TMS) as internal reference (d = 0.0 ppm). IR
spectra were recorded on a Perkin Elmer Paragon 1000 FT-IR
spectrometer employing a KBr disc. Mass spectra were
obtained on a GC–MS instrument operating in TOF-MI? mode.
CHN analysis was done by Atlantic Microlab using a CE-1108
Elemental Analyzer, and values were within 0.4% of the
theoretical values. Thermogravimetric analyses (TGA) were
made with a Pyris TGA instrument. Aheating rate of 10 °C/min
was used and samples (5–10 mg) were contained in a platinum
pan. The sample compartment was purged with dry nitrogen at
50 mL/min during analysis. TA Thermal Advantage software
was used for data analysis. Melting points were determined
using a Pyris differential scanning calorimeter (DSC). Single
crystals suitable for X-ray diffraction study were obtained from
methanol by slow evaporation at room temperature.
Crystallographic Data Collection and Structure
Solution
Crystallographic data for the compound (Z)-3-(4-chlorophe-
nylamino)-1-phenylbut-2-en-1-one, I, is shown in Table 1.
Diffraction intensity data were collected on a Bruker APEX-II
CCD diffractometer at 143(2) K with graphite monochro-
˚
mated MoKa radiation (k = 0.71073 A) and the h range for
data collection was from 2.70 to 28.02°. A total of 2972
(Rint = 0.0790) reflections were measured. An empirical
absorption correction using SADABS was applied for the
data. The structures were solved by direct methods using the
SHELXS-97 program [13]. All nonhydrogen atoms were
refined anisotropically on F2 by fullmatrix least-square using
all unique data; the goodness-of-fit on F2 was 1.190. Hydro-
gen atoms were included in idealized positions with thermal
parameters equivalent to 1.2 times those of the atom to which
they were attached determined by single crystal X-ray dif-
fraction. Selected bond lengths, bond angles, hydrogen coor-
dinates, isotropic displacement parameters and torsion angles
are listed in Tables 2, 3, and 4, respectively.
Synthesis of the Title Compound
A
solution of benzoylacetone (1.62 g, 10.0 mmol),
4-chloroaniline (1.27 g, 10.0 mmol) and two drops of for-
mic acid (conc.) in 50 mL methanol was refluxed for 6–8 h.
On cooling, the product was filtered and recrystallized from
a methanol/ether (5:5 v/v) mixture. A light green solid was
obtained, with a yield of 95%. This compound is stable in
air and light over a period of several months. The synthetic
pathway described in this work is outlined in Scheme 1.
Cl
NH2
O
HN
O
O
HCOOH
+
CH3
CH3
CH3OH,78 °C
Cl
Scheme 1 Synthesis of (Z)-3-(4-chlorophenylamino)-1-phenylbut-2-en-1-one
123

J Chem Crystallogr (2012) 42:543–548
545
˚
Table 1 Crystal data and the structure refinement of (Z)-3-(4-
chlorophenylamino)-1-phenylbut-2-en-1-one
Table 2 Selected bond lengths (A) and bond angles (°) of (Z)-3-(4-
chlorophenylamino)-1-phenylbut-2-en-1-one
˚
(A)
Empirical formula
Formula weight
Temperature (K)
C16H14ClNO
271.73
Bond length
Cl(1)–C(14)
1.742(4)
1.260(5)
1.346(5)
1.416(5)
1.378(6)
1.501(6)
1.420(6)
1.494(6)
(°)
129.8(4)
120.0(4)
120.6(4)
119.4(4)
123.6(4)
122.8(4)
117.5(4)
119.7(4)
122.3(4)
118.7(4)
123.3(4)
117.1(4)
119.9(3)
118.7(3)
143(2) K
O(1)–C(3)
˚
Wavelength (A)
˚
0.71073 A
N(1)–C(1)
Crystal system
Space group
Monoclinic
N(1)–C(11)
P21/n
C(1)–C(2)
Unit cell dimensions
C(1)–C(10)
˚
a (A)
6.4063(19)
7.085(2)
30.194(9)
90°
C(2)–C(3)
˚
b (A)
C(3)–C(4)
˚
c (A)
Bond angle
a (°)
b (°)
C(1)–N(1)–C(11)
N(1)–C(1)–C(2)
N(1)–C(1)–C(10)
C(2)–C(1)–C(10)
C(1)–C(2)–C(3)
O(1)–C(3)–C(2)
O(1)–C(3)–C(4)
C(2)–C(3)–C(4)
C(5)–C(4)–C(3)
C(9)–C(4)–C(3)
C(12)–C(11)–N(1)
C(16)–C(11)–N(1)
C(13)–C(14)–Cl(1)
C(15)–C(14)–Cl(1)
90.824(5)°
c (°)
Volume (A )
90°
1370.3(7) A
3
3
˚
˚
Z
4
Density (calculated) (Mg/m3)
Absorption coefficient (mm-1
F000
1.317 Mg/m3
0.269 mm-1
)
568
0.27 9 0.24 9 0.05 mm3
Crystal size
Theta range for data collection
Index ranges
2.70 to 28.02°
-8 B h B 8, 0 B k B 9,
0 B l B 38
Reflections collected
2,972
Independent reflections
Refinement method
2,975 [R(int) = 0.0000]
Full-matrix least-squares on F2
94.7%
Completeness to theta = 25.50°
Max. and min. transmission
Data/restraints/parameters
Goodness-of-fit on F2
0.9867 and 0.9316
2975/0/173
Table 3 Hydrogen coordinates (9104) and isotropic displacement
2
parameters (A 9 10 ) for (Z)-3-(4-chlorophenylamino)-1-phenylbut-
3
˚
2-en-1-one
1.190
Final R indices [I [ 2r(I) = 2591 R1 = 0.0702, wR2 = 0.1776
data]
x
y
z
U(eq)
H(1)
607
2,862
3,070
4,430
4,404
2,837
1,274
1,345
2,097
4,144
2,296
4,626
4,444
889
2,342
3,080
3,741
4,514
4,865
4,446
3,670
1,980
2,178
2,461
1,567
801
20
22
23
29
33
32
28
30
30
30
25
24
23
23
R indices (all data)
R1 = 0.0790, wR2 = 0.1814
-3
-3
)
˚
Largest diff. peak and hole (e A
˚
0.471 and -1.057 e A
H(2A)
H(5A)
H(6A)
H(7A)
H(8A)
H(9A)
H(10A)
H(10B)
H(10C)
H(12A)
H(13A)
H(15A)
H(16A)
-3295
-2657
-2370
395
2,891
Results and Discussion
2,656
-4423
-4904
-5415
-2795
-2389
2,527
Description of the Crystal Structure
Crystals suitable for single crystal X-ray diffraction were
grown from slow evaporation from a methanol solution at
room temperature. A perspective view of (Z)-3-(4-chlor-
ophenylamino)-1-phenylbut-2-en-1-one, I, showing the
atomic numbering scheme, is depicted in Fig. 1. Com-
pound I has been shown by 1H NMR spectroscopy to exist
in solution in the enaminone and not the enol-imine form.
IR spectroscopy shows only the enaminone form in the
solid state and this has been further confirmed by its crystal
structure. Compound I crystallized in the monoclinic space
980
2,010
980
1,746
group P21/n, with four molecules in the unit cell. In this
compound, there is an absence of any lattice held water
molecules or organic solvent molecules in the unit cell of
123

546
J Chem Crystallogr (2012) 42:543–548
are in the normal range of 1.32–1.45 A°, which is char-
acteristic of delocalized aromatic rings. The C–C–C bond
angles in aromatic rings are around 120° with the variation
being less than 2°, which is characteristic of sp2-hybridized
carbons. The title compound lies in three planes with plane
I [O1, C3, C2, C1, and N1] making a dihedral angle of
36.30 and 30.05° with plane II [C16, C15, C13, C12, C11,
and C14], and plane III [C9, C5, C6, C8, C7, and C4],
whereas the plane II forms a dihedral angle of 7.59° with
plane III. The molecular packing diagram (Fig. 2) shows
two layers of molecules, which are independently arranged
in the unit cell. Molecules forming each layer are not
connected through intermolecular hydrogen bonding. In
each layer, the molecules are alternatively parallel. The
molecular packing diagram also shows the presence of one
intra-molecular hydrogen bond. One of the hydrogens, H1
of the NH group, is involved in intra-molecular hydrogen
bonding with the O1 of the C=O entity. This hydrogen
bonding stabilizes the crystal packing.
Table 4 Torsion angles [°] for (Z)-3-(4-chlorophenylamino)-1-phe-
nylbut-2-en-1-one
C(11)–N(1)–C(1)–C(2)
C(11)–N(1)–C(1)–C(10)
N(1)–C(1)–C(2)–C(3)
C(10)–C(1)–C(2)–C(3)
C(1)–C(2)–C(3)–O(1)
C(1)–C(2)–C(3)–C(4)
O(1)–C(3)–C(4)–C(5)
C(2)–C(3)–C(4)–C(5)
O(1)–C(3)–C(4)–C(9)
C(2)–C(3)–C(4)–C(9)
C(3)–C(4)–C(5)–C(6)
C(3)–C(4)–C(9)–C(8)
C(1)–N(1)–C(11)–C(12)
C(1)–N(1)–C(11)–C(16)
N(1)–C(11)–C(12)–C(13)
N(1)–C(11)–C(16)–C(15)
-179.8(4)
2.4(6)
-2.4(7)
175.4(4)
0.1(7)
-177.3(4)
151.2(4)
-31.3(6)
-27.8(6)
149.8(4)
-178.6(4)
179.3(4)
40.0(6)
-142.7(4)
178.6(4)
-177.3(4)
the determined structure. The C3=O1 and C3–C2 bond
distances [1.260 (5) and 1.420 (6) A°, respectively] further
confirm the existence of the enamino-ketone. The bond
distances in the C2=C1–N1 chain indicate greater electron
delocalization [C2=C1 = 1.378(6) A° and N1–C1 =
1.346(5) A°]. The C–C bond distances in aromatic rings
1H-NMR and 13C-NMR spectroscopy
1H-NMR and 13C-NMR spectra of the title compound was
recorded in CDCl3 solvent and the spectra are presented in
1
Figs. 3 and 4, respectively. In the H-NMR spectrum, a
broad singlet at 13.07 ppm corresponds to the N–H proton
Fig. 1 Molecular diagram of
(Z)-3-(4-chlorophenylamino)-1-
phenylbut-2-en-1-one (I),
showing atom labeling
scheme. 50% probability
amplitude displacement
ellipsoids are shown
Fig. 2 Perspective view of the
molecular packing of (Z)-3-(4-
chlorophenylamino)-1-
phenylbut-2-en-1-one (I)
123

J Chem Crystallogr (2012) 42:543–548
547
(D2O exchangeable). Appearance of the NH signal down-
field to TMS is due to presence of intramolecular hydrogen
bonding between the amine proton and the oxygen of the
ketone functional group. The aromatic protons of the both
phenyl rings are observed as multiplets at 7.12–7.08,
7.35–7.32, 7.46–7.43, and 7.92–7.89 ppm, respectively.
The resonance due to the CH3 protons was observed as a
singlet at 2.13 ppm while that of CH also appeared as a
singlet at 5.91 ppm.
The 13C-NMR spectrum of I showed two peaks at
188.95 and 161.69 ppm which are assigned to carbonyl
(C=O) carbon and carbon of the C–NH group, respectively.
A peak at 20.38 ppm is due to carbon of the –CH3 group.
The –CH carbon appears at 94.65 ppm. The peaks
observed at 125.89, 127.06, 128.30, 129.29, 131.06, and
130.09 ppm are due to the aromatic carbons.
Fig. 3 1H NMR spectrum of (Z)-3-(4-chlorophenylamino)-1-phe-
nylbut-2-en-1-one in CDCl3
FT-IR Spectrum
The FT-IR spectrum for the title compound was recorded
in the region from 400 to 4,000 cm-1. The bands at 1,618
(mas) and 1,492 (ms) cm-1 may be assigned to the carbonyl
group (C=O) and the band at 3,056 (m) cm-1 is typical of
the NH group. Weak to medium absorptions around
3,100–3,000 cm-1 observed corresponding to the =C–H
stretch of aromatic ring.
Mass Spectrometry and Thermal Studies
The mass spectrum of compound I is given in Fig. 5. The
mass spectrum was analyzed by GC–MS. The peak
observed at m/z 271.074 suggested the molecular formula
C16H14ClNO of the title compound.
The thermal behavior has been investigated using ther-
mogravimetric techniques in the temperature range from 30
to 1,000 °C at a heating rate of 10 °C min-1. A sharp
Fig. 4 13C NMR spectrum of (Z)-3-(4-chlorophenylamino)-1-phe-
nylbut-2-en-1-one in CDCl3
270.0676
100
271.0742
272.0687
%
105.0333
77.0387
194.0373
166.0414
131.0721
273.0720
256.0575
75.0235
63.0230
196.0348
152.0257
168.0399
78.0451
80
274.0819
235.0991
240
296.1021 342.0924
300 320 340
357.0744
360
0
m/z
60
100
120
140
160
180
200
220
260
280
Fig. 5 Mass spectrum of (Z)-3-(4-chlorophenylamino)-1-phenylbut-2-en-1-one
123

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J Chem Crystallogr (2012) 42:543–548
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK [fax: ?44 1223 336-033; e-mail: deposit@ccdc.cam.
ac.uk or www.ccdc.cam.ac.uk].
Acknowledgments The authors would like to thank the National
Science Foundation (CHE-0911061) for financial support. We also
´
acknowledge the Ministerio de Ciencia y Tecnologıa de Costa Rica
(MICIT), Consejo Nacional para Investigaciones Cientıficas y Tec-
´
´
´
´
nologicas (CONICIT), and the Centro de Electroquımica y Energıa
Quımica (CELEQ) at the Universidad de Costa Rica for providing
´
partial financial support for an internship for Diego Gonzalez-Flores
at Central Michigan University.
References
Fig. 6 TGA/DSC of (Z)-3-(4-chlorophenylamino)-1-phenylbut-2-
en-1-one
1. Sandler SR, Karo W (1986) Organic functional group preparation
11:291–319. Academic Press, New York
2. Chen H, Rhodes J (1996) J Mol Med 74:497–504
3. Khosropour AR, Khodaei MM, Kookhazadeh M (2004) Tetra-
hedron Lett 45:1725–1728
4. Kascheres C, Negri G, Ferreira MCM, Sabino LC (2001) J Chem
Soc Perkin Trans 2:2237–2243
5. Zhuo JC (1997) Molecules 2:31–35
6. Edafiogho IO, Moore JA, Alexander MS, Scott KR (1994)
J Pharm Sci 83:1155–1170
7. Hinko CN, Change H, El-Assadi A, Nicholson JM (1993) J Med
Chem 36:1947–1955
endothermic peak was observed at a temperature 134.05 °C,
indicating that the compound melts at 134.05 °C and it was
further confirmed by melting point analysis (134–136 °C)
of the compound. At a temperature 302.71 °C, one more
sharp endothermic peak occurred corresponding to boiling
point of the compound. Onset of mass loss in the compound
occurred at 94.88 °C and terminated at 302.71 °C as
observed by weight loss curve of the TGA data in Fig. 6.
8. Christoffers J (2003) Chem Eur J 9:4862–4867
9. Christoffers J, Kreidler B, Unger S, Frey W (2003) Eur J Org
Chem 2845–2853
Supplementary Material
10. Tietze LF, Bergmann A, Brill G, Bruggemann K, Hartief U, Voss
E (1989) Chem Ber 122:83–94
11. Kim J, Hwang JW, Kim Y, Lee MH, Han Y, Do Y (2001)
J Organomet Chem 620:1–7
12. Doherty S, Errington RJ, Housley N, Ridland J, Clegg W,
Elsegood MRJ (1999) Organometallics 18:1018–1029
13. Sheldrick GM (2008) Acta Cryst A64:112–122
Crystallographic data for the structure reported in this
article have been deposited with the Cambridge Crystal-
lographic Data Center with the deposition number 844992.
A copy of the data can be obtained free of charge from the
123