Synthesis, characterization, crystallographic studies of 5-acetyl-8-hydroxyquinoline and their chalcone derivatives

Article abstract of DOI:10.14233/ajchem.2020.22628

An efficient, easy and one pot synthesis for the Friedel-Craft acetylation reaction of quinolines was developed. The reaction between 8-hydroxyquinoline and acetyl/benzoyl chloride in nitrobenzene immediately flocculates as yellow precipitate. On further

Full text of DOI:10.14233/ajchem.2020.22628

Asian Journal of Chemistry; Vol. 32, No. 7 (2020), 1609-1613
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2020.22628
Synthesis, Characterization, Crystallographic Studies of
5-Acetyl-8-hydroxyquinoline and Their Chalcone Derivatives
1,
2,
2,
1,
1,*,
C.B. VAGISH , KARTHIK KUMARA , N.K. LOKANATH , K. AJAY KUMAR
and P.G. CHANDRASHERKAR
1Department of Chemistry, Yuvaraja′s College, Mysuru-570005, India
2Department of Studies in Physics, University of Mysore, Mysuru-570005, India
*Corresponding author: E-mail: pgc2031@gmail.com
Received: 9 January 2020;
Accepted: 17 March 2020;
Published online: 27 June 2020;
AJC-19920
An efficient, easy and one pot synthesis for the Friedel-Craft acetylation reaction of quinolines was developed. The reaction between
8-hydroxyquinoline and acetyl/benzoyl chloride in nitrobenzene immediately flocculates as yellow precipitate. On further addition of
Lewis acid causes the Friedel-Craft acetylation leads to formation of acetylated quionlines in good yields. The structure of compound 5-
acetyl-8-hydroxyquinoline (3) was confirmed by single crystal X-ray diffraction studies. The compound crystallizes in the monoclinic
crystal system with the space group P21/c. The synthesized acetylated quionlines undergoes condensation reaction with aromatic aldehydes
leads to 8-hydroxyquinoline chalcones derivatives. The products were characterized by spectral studies, elemental analysis and single
crystal X-ray diffraction studies.
Keywords: Friedel-Craft acetylation, 8-Hydroxyquinoline, Chalcones.
trend and selectivity is forming stable, insoluble complex with
metal ion with any one oxidation state. While the same metal
ion with other oxidation state is not favorable leads the quinoline
molecule redox reaction. It forms strong complex with ferric
ions while ferrous ions are oxidized to ferric ions [6]. The deri-
vatives of 8-hydroxy quinoline are good inhibitors enzyme Ras
protease. These enzymes are present in endoplasmic reticulum
which is responsible of caaX proteins, there by plays significant
role in cell signaling process. Quionolines which forms square
planar complexes with first row transition elements and these
complexes tend to show DNA binding property and anticancer
activity [7]. 8-Hydroxyquinoline bidentate ligand but coord-
ination number varies according to the nature of metal ions.
Aluminum ion forms octahedral, zinc and magnesium ions forms
distorted tetrahedral,cadmium and zinc ions forms bimetallic
complexes [8]. The RuII (η6-p-cymene) complexes exhibit the
minor impact on cytotoxicity [9]. The impressing biological
significance of quinoline scaffolds makes us for the synthesis
of acetyl derivatives. Herein, we reported the synthesis of
5-acetyl-8-hydroxy quinoline by one pot synthesis. The phenolic
and acetyl group in the 8th and 5th position can be post trans-
formed to other active groups.
INTRODUCTION
By replacing the methyne group of naphthalene with iso-
electronic species nitrogen atom forms the heterocycle quino-
line. Quinoline and its derivatives have been exhibiting broad
opening to pharmacological activities. The halogenated deri-
vatives of 8-hydroxy quinolines are the good chelator for copper,
zinc and iron metal ions and these halogenated compounds
exhibits immense biological activity. These compounds are
the promising scaffolds against many non-communal diseases
such as cancer, Alzheimer′s and Parkinson′s disease [1-3]. In
recent years, aluminium complexes of 8-hydroxyquinoline
derivatives exhibit organic light emitting diode (OLEDs) property,
used in electroluminescent devices [4]. Introduction of nitro
group to organic molecule generally requires harsh condition
such as nitrating mixture (conc. sulphuric and nitric acid) but
in case of quinolines amines can be nitrated easily at C-5 or
C-7 position by using sodium nitrite and copper nitrate as catalyst
cheap catalyst with excellent yield. The reaction proceeds via
C-H activation process [5].
8-Hydroxyquinoline shows good chelation with wide range
of metal ions includes s-, p-, d- and f-block elements. The main
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1610 Vagish et al.
Asian J. Chem.
Further chalcones are the important scaffolds which is repre-
atoms were positioned geometrically. After several cycles of
refinement, the final difference Fourier map showed peaks of
no chemical significance and the residuals were saturated to
accepted values. The geometrical calculations were carried out
using the program PLATON [18]. The molecular and packing
diagrams were generated using the software MERCURY [19].
Synthesis of 5-acetyl-8-hydroxyquinoline (3):To a solution
of acetyl chloride (2) (1.62 g, 20 mmol) in nitrobenzene (3-5
mL), introduce 8-hydroxyquinoline (1) (3 g, 20 mmol), a yellow
folculant precipitate out. To a above reaction mixture, added
about 5 g aluminium chloride/titanium chloride with constant
shaking, the precipitate disappeared and a clear semi-solid was
resulted. It was kept at 70 ºC for 12 h in a flask fitted with a
calcium chloride tube. On cooling, some crushed ice and 100
mL 10% HCl was added to it and the separated nitrobenzene
was driven off with steam. On standing overnight, the separated
hydrochloride of 5-acetyl-8-hydroxyquinoline (3) was filtered.
It was dissolved in water and on the addition of sodium acetate
to it, the free base separated out. It was recrystallized from hot
water; (55% of the theoretical) after recrystallization. Compound
3 is colourless hair-like needles from hot water (Scheme-I).
Yield 55%; m.p.: 112-114 ºC; MS m/z: 187.06 (100.0%) (M+);
Anal. calcd. (found) for C11H9NO2 (%): C, 70.58 (70.51); H,
4.85 (4.78); N, 7.48 (7.43).
Synthesis of 1-(8-hydroxyquinolin-5-yl)-3-(arylidene)-
prop-2-en-1-one (5a-d): To a solution mixture of 5-acetyl-8-
hydroxyquinoline (3, 10 mmol) and aromatic aldehydes (4a-d,
10 mmol) in ethyl alcohol, dry HCl was passed through the
bend tube for about 3-5 min. The solution mixture was stirred
at room temperature for 1-2 h. The progress of the reaction
was monitored by TLC.After the completion, the precipitation
of the reaction mixture was occurred indicating the completion
of the reaction. The solids separated were filtered, washed
successively with 2% aqueous sodium carbonate. The crude
solids were recrystallized from ethanol to obtain 1-(8-hydroxy-
quinolin-5-yl)-3-(aryl)prop-2-en-1-one (5a-d) in moderate
yield (Scheme-I).
sented by α,β-unsaturated ketone group which is sandwitched
between any two aromatic groups. Chalcones are naturally
occurring in many floras and are of great medicinal importance.
The flora families Leguminaceae, Fabaceae, zinzeberaceae,
Fabaceae contains chalcones and are used in folk medicines.
Numerous literatures revealed the importance of these chalcone
scaffolds [10]. In this perspective, we planned to construct
chalcones containing 8-hydroxy quinoline moiety. Chalcones
are chief precursor for variety of heterocyclic compounds with
heteroatoms nitrogen, sulphur, oxygen, etc. [11,12], The size
of heterocyclic ring may vary from three membered ring such
as aziridnes [13] to seven-membered rings such as benzothia-
zepines [14]. Five-membered rings such as pyrazolins, pyrazoles,
pyrazole carboxamide and pyrazole thiamides [15-20].
EXPERIMENTAL
Melting points were determined by an open capillary tube
method and are uncorrected. Purity of the compounds was
checked on thin layer chromatography plates precoated with
silica gel using the solvent system ethyl acetate: n-hexane (1:4
v/v). The spots were visualized under UV light and also using
iodine chamber. 1H NMR were recorded using 400 MHzAgilent-
NMR spectrometer. The solvent CDCl3 with TMS as an internal
standard was used to record the spectra. The chemical shifts are
expressed in δ ppm. Mass spectra were obtained on ESI/APCI-
Hybrid Quadrupole, Synapt G2 HDMS ACQUITY UPLC
model spectrometer. Elemental analysis was obtained on aThermo
Finnigan Flash EA 1112 CHN analyzer. Purification of com-
pounds was done by column chromatography on silica gel
(70-230 mesh Merck)
X-ray diffraction studies: Single crystals of suitable
dimensions were chosen carefully for X-ray diffraction studies.
The X-ray intensity data of the compounds were collected using
Rigaku XtaLAB Mini diffractometer with X-ray generator
operating at 50 kV, 12 mA and MoKα radiation. Data were
collected with χ fixed at 54º, for different settings of ϕ (0º and
360º), keeping the scan width of 0.5º with exposure time of 4 s
and the sample to detector distance was fixed to 50 mm. The
complete intensity data sets were processed using CRYSTAL
CLEAR [15]. The crystal structures were solved by direct
method and refined by full-matrix least squares method on F2
using SHELXS and SHELXL programs [16,17]. All the non-
hydrogen atoms were refined anisotropically and the hydrogen
1-(8-Hydroxyquinolin-5-yl)-3-phenylprop-2-en-1-one
(5a): Yield 67%, m.p.: 233-235 ºC; 1H NMR: δ 7.06 (d, 1H,
COCH), 6.68 (s, 1H, Ar-H), 7.43 (d, 2H, Ar-H) 7.38 (d, 2H,
Ar-H), 7.51 (m, 1H,Ar-H), 7.54 (d, 2H,Ar-H), 8.06 (d, 1H, =CH),
8.42-8.97 (m, 3H, Ar-H), 9.02 (s, 1H, -OH); MS m/z: 275.09
(100.0%) (M+); Anal. calcd. (found) for C18H13NO2 (%): C,
78.53 (78.50); H, 4.76 (4.70); N, 5.09 (5.03).
O
CH3
Dry HCl
room temp,
1-2 h
R
CH
CH
O
AlCl3/TiCl4
O
Nitrobenzene
+
H3C
Cl
60-700 C, 12hrs
O
H
N
N
HO
2
1
HO
3
N
HO
5(a-d)
R
R=H; Cl; F; CH3
4(a-d)
Scheme-I: Reaction pathway for the synthesis of 1-(8-hydroxyquinolin-5-yl)-3-(aryl)prop-2-en-1-one 5(a-d)

Vol. 32, No. 7 (2020)
Synthesis and Crystallographic Studies of 5-Acetyl-8-hydroxyquinoline and Their Chalcone Derivatives 1611
3-(4-Chlorophenyl)-1-(8-hydroxyquinolin-5-yl)prop-2-
en-1-one (5b): Yield 72%, m.p. 276-278 ºC; 1H NMR: δ 6.58
(d, 1H, COCH), 7.16 (d, 2H, Ar-H), 7.29 (m, 2H, Ar-H), 7.75
(d, 1H, =CH), 7.87 (d, 2H, Ar-H), 8.48-8.6 (m, 3H, Ar-H), 9.01
(s, 1H, -OH); MS m/z: 309.05 (100.0%) (M+), 311.05 (32.0%)
(M+2); Anal. calcd. (found) for C18H12NO2Cl (%): C, 69.80
(69.76); H, 3.91 (3.86); N, 4.52 (4.48).
The compound 3 (CCDC: 1922218) crystallized as pale
yellow coloured needle shaped crystals suitable for single crystal
X-ray diffraction (crystal size 0.24 mm × 0.24 mm × 0.24 mm).
The crystal structure was found to be monoclinic, P21/c. The
Oak Ridge Thermal-Ellipsoid Plot Program (ORTEP) diagram
of molecule 3 with thermal ellipsoids drawn at 50% probability
and packing of molecules are shown in Figs. 1 and 2 respectively.
3-(4-Fluorophenyl)-1-(8-hydroxyquinolin-5-yl)prop-2-
en-1-one (5c):Yield 70%, m.p.: 246-248 ºC;1H NMR: δ 6.72
(d, 1H, COCH), 7.43 (d, 2H, Ar-H), 7.41 (m, 2H, Ar-H), 7.81
(d, 1H, Ar-H), 7.93 (d, 2H, =CH), 8.652-8.73 (m, 3H, Ar-H),
8.97 (s, 1H, -OH); MS m/z: 293.08 (100.0%), (M+);Anal. calcd.
(found) for C18H12NO2F (%): C, 73.71 (73.69); H, 4.12 (4.10);
N, 4.78 (4.72).
1-(8-Hydroxyquinolin-5-yl)-3-(p-tolyl)prop-2-en-1-
one, (5d): Yield 70%, m.p.: 257-259 ºC; 1H NMR: δ 2.39 (s,
3H, CH3), 6.64 (d, 1H, COCH), 7.26 (d, 2H, Ar-H), 7.34 (m, 2H,
Ar-H), 7.79 (d, 1H, Ar-H), 7.93 (d, 2H, =CH), 8.432-8.532 (m,
3H, Ar-H), 8.93 (s, 1H, -OH); MS m/z: 289.11 (100.0%) (M+);
Anal. calcd. (found) for C19H15NO2 (%): C, 78.87 (78.81); H,
5.23 (5.20); N, 4.84 (4.78).
RESULTS AND DISCUSSION
The synthetic procedure involves a solution of 8-hydroxy-
quinoline containing nitrobenzene acetyl chloride was intro-
duced which causes the formation of yellow precipitate. To a
reaction mixture, 1 equivalent of anhydrous AlCl3 or TiCl4 was
added and fitted with a guard tube and reaction mixture was
heated to 60-70 ºC for 12 h. After the completion of reaction
mixture, 6M HCl was added and driven off the nitrobenzene by
steam distillation. The aqueous layer was kept overnight and
yellow crystals of hydrochloride salt were formed. The crystals
were collected and on addition of aqueous sodium acetate leads
to the formation of 5-acetyl-8-hydroxyquinoline (3) in average
yield.
Fig. 1. ORTEP of the molecule 5-acetyl-8-hydroxyquinoline (3) drawn at
50% probability level
The effect of temperature plays an important role in Fries
rearrangement at low temperature 60-70 ºC, where the acetyl
group is migrated to para-position to the phenolic group, but
at high temperature above 120 ºC mainly favours the formation
of ortho-isomer and at ambient temperature it gives both ortho-
and para-isomers. Herein, the para-position is favoured by
maintaining the low temperature. After the confirmation of
the acetylated product, then it was condensed with various
aromatic aldehydes. Normal Claisen-Schmidth condensation
reaction under basic condition such as NaOH/KOH often leads
to poor yield, so it was planned to synthesize under acidic cond-
ition. The dry HCl was passed on to the reaction mixture. To a
solution of 5-acetyl-8-hydroxyquinoline (3) in ethanol, aromatic
aldehydes were added with constant stirring.After 5 min, catalytic
amount of dry HCl was passed on to the reaction mixture using
a passing tube. The resultant mixture was stirred for 1-3 h. The
completion of the reaction was monitored by the TLC plates.
After the completion of reaction, the mixture was poured into
ice-cold water. The precipitate formed was filtered and washed
with 2% aqueous sodium carbonate solution. The product was
dried and purified by recrystallization using ethanol as solvent.
Fig. 2. Packing of molecules when viewed down along a axis
Further the chalcones formed were also characterized by
spectral studies. In 1H NMR analysis by considering compound

1612 Vagish et al.
Asian J. Chem.
TABLE-1
5d as representative compound among the series, the alkenyl
proton each for -C=CH and -CH=C appeared as doublets at δ
6.631-6.653 (J = 8.8 Hz) and 7.780-7.818 (J = 15.2 Hz) ppm
respectively. High range coupling constant (J = 8.8-15.2 Hz)
confirms E-geometry around olefinic bond. The signals appeared
as singlet for three protons at δ2.39 were assigned to CH3 protons
attached to phenyl ring. In the aromatic region due to methyl
substitution at para-position, the two doublets are appeared
in the region of 7.251-7.271 and 7.920-7.940 ppm, respectively
for four aromatic protons. A group of multiplets are observed
in the aromatic region 7.322-7.361 and 8.432-8.532 ppm attri-
buted to aromatic protons. The highly deshielded phenolic group
attached appears as singlet at 8.932 ppm. further, the mass
spectrum provides the molecular ion peak at m/z 289.11 confirms
the formation of 1-(8-hydroxyquinolin-5-yl)-3-(p-tolyl)prop-
2-en-1-one (5d). Similar and consistent pattern signals were
observed in 1H NMR, mass spectra and elemental analysis of
the synthesized compounds 5(a-d), which strongly evidences
the structure for the synthesized compounds.
Data value and validation: Compound 1-(8-hydroxy-
quinolin-5-yl)ethan-1-one (3) crystallizes in the monoclinic
P21/c space group with unit cell parameters a = 7.439(13) Å ,
b = 10.033(16) Å, c = 13.767(2) Å, α = 90º, β = 93.306(7)º
and Z = 4. The molecular structure assumes the acetyl group
attached to the fifth position to the quinoline ring as expected.
The migration of acetyl group can be achieved by temperature
at lower temperature 60-70 ºC to the fifth position, higher temp-
erature leads to seventh position. The ORTEP of a molecule
with displacement ellipsoids drawn at 50% probability level
is shown in Fig. 1. The molecules exhibit layered stacking when
viewed down along the a-axis as shown in Fig. 2. Crystal data,
and structure refinement data, bond lengths, bond angles and
torsion angles are given in Tables 1-4.
CRYSTAL DATA AND STRUCTURE REFINEMENT DETAILS
OF THE COMPOUND 5-ACETYL-8-HYDROXYQUINOLINE (3)
Empirical formula
CCDC
Formula weight
Temperature
Wavelength
C11H9NO2Cl
1922218
222.64
293 K
0.71073 Å
Reflections for cell determination 3808
Crystal system
Space group
Cell dimensions
Monoclinic
P21/c
a = 7.439(13) Å; b = 10.033(16)
Å; c = 13.767(2) Å
α = γ = 90° and β = 93.306(7)°
Volume
Z
Density (calculated)
Absorption coefficient
F000
1026(2) Å3
4
1.441 Mg m-3
0.349 mm-1
460
Crystal size
0.240 × 0.240 × 0.240 mm
3.41° to 27.50°
θ range for data collection
Index ranges
-9 ≤ h ≤ 9; -12 ≤ k ≤ 12;
-17 ≤ l ≤ 5
3808
2297 [Rint = 0.0497]
Full matrix least-squares on F2
2297 / 0 / 138
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final [I > 2σ(I)]
1.059
R1 = 0.0577, wR2 = 0.1493
R indices (all data)
Extinction coefficient
R1 = 0.0774, wR2 = 0.1692
CIF-file generated for 8HQAC
P21/c R = 0.06
0.669 and -0.352 e Å-3
Largest diff. peak and hole
TABLE-2
BOND LENGTHS (Å)
The title compound is confirmed as the molecular ion. The
free Cl− ion is also crystallized with the title compound. The
molecular structure is stabilized with the hydrogen bond inter-
actions of the type C-H...O and O-H...Cl. The hydrogen bond
geometry is given in Table-5. The structure is also stabilized
by π···π interaction [20-22]. The Cg(1)···Cg(2) (Cg(1) is the
centroid of the ring N(2)-C(1)-C(6)-C(5)-C(4)-C(3) and Cg(2)
is the centroid of the ring C(1)-C(6)-C(7)-C(8)-C(9)-C(10)
with a Cg-Cg distance of 3.605(6) Å, α = 2.83(12)º, β = 18.5º,
γ = 21.2º, a perpendicular distance of Cg(2) on Cg(1) is -3.3609
(10) Å and a symmetry code of -x, 1-y, -z.
Atoms
O11-C10
O13-C12
N2-C3
N2-C1
C1-C6
C1-C10
C3-C4
C4-C5
Bond length
Atoms
C5-C6
C6-C7
C7-C8
C7-C12
C8-C9
C9-C10
C12-C14
–
Bond length
1.413(4)
1.443(4)
1.371(4)
1.487(5)
1.399(5)
1.366(5)
1.502(5)
–
1.339(4)
1.211(5)
1.323(4)
1.375(4)
1.406(4)
1.421(4)
1.377(5)
1380(5)
TABLE-3
BOND ANGLES (°)
Conclusion
Atoms
Angle Atoms
122 2(2)
120
117
122
120
Angle
C1-N2-C3
N2-C1-C6
N2-C1-C10
C6-C1-C10
N2-C3-C4
C3-C4-C5
C4-C5-C6
C1-C6-C7
C5-C6-C7
C1-C6-C5
C6-C7-C8
.
.
.
.
.
C8-C7-C12
C6-C7-C12
C7-C8-C9
C8-C9-C10
O11-C10-C9
C1-C10-C9
O11-C10-C1
O13-C12-C14
C7-C12-C14
O13-C12-C7
–
120
121
123
120
126
118
115
119
119
121
.
.
.
.
4(2)
8(2)
7(3)
0(2)
An easily accessible and convenient Friedel-Craft proce-
dure for the synthesis of acetylation of quinoline rings were
revealed in this study. Further the post transformation of acetyl
group to chalcones is also represents the worth of this work.
The structure of chloride salt of 5-acetyl-8-hydroxyquinoline
is studied by single crystal X-ray diffraction studies. The comp-
ound crystallizes in the monoclinic crystal system with the
space group P21/c. The molecular structure is stabilized with
the hydrogen bond interactions of the type C-H...O, O-H...Cl
and π···π interactions.
1(2)
4(2)
5(2)
6(3)
4(3)
1(2)
8(2)
6(2)
6(2)
8(2)
.
5(2)
119
121
117
125
116
117
.
.
.
.
.
.
.2(2)
.
.
3(2)
2(3)
.6(3)
.
2(3)
–

Vol. 32, No. 7 (2020)
Synthesis and Crystallographic Studies of 5-Acetyl-8-hydroxyquinoline and Their Chalcone Derivatives 1613
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TABLE-4
TORSION ANGLES (°)
Atoms
Angle
-2 3(4)
176.4 (2)
1.0(4)
Atoms
Angle
178 0(2)
1.6(3)
176.8(2)
176.1(2)
-5.5(4)
C3-N2-C1-C6
C3-N2-C1-C10
C1-N2-C3-C4
N2-C1-C6-C5
N2-C1-C6-C7
C10-C1-C6-C5
C10-C1-C6-C7
N2-C1-C10-O11
N2-C1-C10-C9
C6-C1-C10-O11
C6-C1-C10-C9
N2-C3-C4-C5
C3-C4-C5-C6
C4-C5-C6-C1
.
C4-C5-C6-C7
C1-C6-C7-C8
C1-C6-C7-C12
C5-C6-C7-C8
-
.
-
1.9(3)
179.8(2)
-176.8(2)
1.1(3)
-0.5(3)
-178.8(2)
178.2(2)
-0.1(4)
0.6(4)
C5-C6-C7-C12
C6-C7-C8-C9
1.2(4)
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C12-C7-C8-C9
C6-C7-C12-O13
C6-C7-C12-C14
C8-C7-C12-O13
C8-C7-C12-C14
C7-C8-C9-C10
C8-C9-C10-O11
C8-C9-C10-C1
-177.3(2)
-15.6(4)
167.2(3)
162.8(3)
-14.4(4)
-0.1(4)
https://doi.org/10.1039/C6RA19583K
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-0:9(4)
-0.3(3)
-178.5(2)
-0.4(4)
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TABLE-5
GEOMETRIC PARAMETERS FOR
HYDROGEN BOND INTERACTIONS (Å, °)
D–H···A
D–H
0.93
0.93
0.82
H···A
2.21
2.39
2.12
D···A
D–H···A
122
152
C(5)---H(5)...O(13)*
C(4)---H(4)...O(13)i
O(11)---H(11)...Cl(15)ii
2.818(6)
3.242(7)
2.936(6)
172
*Intra, inter- i: 1-x, 1/2+y, 1/2-z; ii: -x, 1-y, -z.
https://doi.org/10.1021/jo0101407
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ACKNOWLEDGEMENTS
The authors are grateful to National Single Crystal Diffracto-
meter Facility, Department of Studies in Physics, University
of Mysore, Mysuru, India for providing the X-ray intensity
data.
15. Rigaku, CrystalClear-SM Expert, Rigaku Corporation, Tokyo, Japan
(2011).
16. G.M. Sheldrick, Acta Crystallogr. C, 71, 3 (2015);
https://doi.org/10.1107/S2053229614024218
CONFLICT OF INTEREST
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The authors declare that there is no conflict of interests
regarding the publication of this article.
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