Highly efficient synthesis of new 2H-chromene dyes using Cu-SBA-15

Article abstract of DOI:10.13005/ojc/320525

In this work, some new azotated 2H-chromene derivatives were successfully synthesized by use of mesoporous Cu-SBA-15 as nanocatalyst leading short reaction times and high yields. By this research, the scope of azo compounds was increased.

Full text of DOI:10.13005/ojc/320525

ISSN: 0970-020 X
CODEN: OJCHEG
2016, Vol. 32, No. (5):
Pg. 2543-2548
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Free Access, Peer Reviewed Research Journal
www.orientjchem.org
Highly Efficient Synthesis of New
2H-chromene Dyes Using Cu-SBA-15
SHIRIN FARAJI KAMAzANI*, SIAvASH SALEK SOLTANI and AFSANEH zONOUzI
School of Chemistry, University College of Science, University of Tehran, Tehran, Iran.
*Corresponding author E-mail: Shirinfaraji58@gmail.com
http://dx.doi.org/10.13005/ojc/320525
(Received: August 01, 2016; Accepted: September 30, 2016)
ABSTRACT
In this work, some new azotated 2H-chromene derivatives were successfully synthesized
by use of mesoporous Cu-SBA-15 as nanocatalyst leading short reaction times and high yields. By
this research, the scope of azo compounds was increased.
Keywords: Azo dye, Chromene, Mesoporous, Catalyst. Cu-SBA-15.
INTRODUCTION
class of all synthetic dyes that are widely used in
the world22.The importance of azo dyes returns to
their significant physicochemical features such as
stability23, optical properties24,25 and their extensive
applications in chemosensors26,27, liquid crystals28
and nanotubes29.
2H-chromenes are very important
heterocyclic compounds which have shown
biological activities1-4, some medical properties
such as antihypertensive5 and cardio protectors as
well as hypoglycemic agents6,7. Some of them are
insecticide compounds8. In the recent years, they
have been used in sensors for detection of metals
and some compounds with high selectivity9,10.Until
now, diverse methods have been published for the
synthesis of 2H-benzopyran derivatives11-17.They are
also good intermediates that have been applied in
Recently, an enhancing attention has been
concentrated on the development of new synthetic
paths in processes employing functionalized
mesoporous catalysts30.
Mesoporous material has been grown in
academia because of its extraordinary surface area,
narrow size distribution of porosity, heat resistance
and mechanical stability that make them outstanding
several organic synthesis18-20
.
Azo compounds are very considerable in
dyes and pigments industry21. They are the main
catalysts31,32
.

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In this work, we use them for the synthesis rapid stirring in ice bath. The reaction mixture was
of new class of azo dyes in very good conditions.
stirred for 1 hour in 0oC. The solution was remained
in refrigerator for 12 hours. Then, the solvent was
evaporated with vacuum rotary. Afterward, the
precipitate was washed with sufficient n-hexane.
ExpERIMENTAL
General information
Inthisresearch,5-Phenylazo-salicylaldehyde
In order to recovery of the catalyst, the
1 was synthesized similar to the reported product was dissolved in acetonitrile (10 ml) and
methods33, 34 , but optimized, and also the mesoporous shaken for 5 min. then the catalyst was filtered
Cu-SBA-15 catalyst was prepared by literature35.
and washed with enough ethyl acetate and the
filtrate was evaporated to gain crude product. It was
All of the chemicals and solvents were recrystallized from ethanol to obtain orange pure
purchased from Merck (Germany), Sigma-Aldrich crystals, mp, 134-136 oC.
(United States) and Fluka (Switzerland) corporations.
They were used without anymore purification. 2b-f.
TLC was performed on precoated plastic sheets
The similar procedure was used leading
(25DCUV-254). Melting points totally were weighed Representative spectral data
on an electrothermal Gallenkamp melting point 1-(2-Hydroxy-2-methyl-6-(phenyldiazenyl)-2H-
apparatus and are not corrected.Elemental analysis chromene-3-yl) ethanone (2a)
for C, H and N were done using a Thermo Finnigan
IR (KBr) (nmax, cm”1): 3473, 1653, 1431,
Flash EA1112 instrument. IR spectra were obtained 1163, 1083. 1HNMR (250 MHz, DMSO):dH 1.87 (3H,
on a Shimadzu FT-IR-4300 spectrophotometer s, CH3), 2.47 (3H, s, OCH3), 4.4 (1H, brs, OH), 7.07
1
as KBr discs. HNMR and 13CNMR spectra were (1H, d, J = 8.75 Hz, H8), 7.46-7.87 (7H, Ar Protons),
analyzed on a Bruker 300 MHz spectrometer (but 2a, 7.97 (1H, dd, J = 8.5 Hz, J = 2.5 Hz, H7). 13CNMR
2c and 2d compounds were analyzed on a Bruker (62 MHz, DMSO):dC 32.5 (CH3), 32.6 (CH3), 111.3,
250 MHz spectrometer) in CDCl3, and DMSO- d6, 122.5, 125.1, 127.6, 128.6, 131.9, 134.7, 136.3,
solutions and chemical shifts were noted in d units 139.2, 140, 151.5, 157.2, 161.2 (Alkene and Aryl
by using TMS, as standard.
carbons), 201.6 (C=O).
General procedure for the synthesis of 1 - ( 2 - H y d rox y - 8 - m e t h ox y - 2 - m e t hy l - 6 -
5-phenylazo-salicylaldehyde (1)
To a solution of substituted aniline (0.05 (2b)
mol) in a small portion of water was slowly added
(phenyldiazenyl)-2H-chromene-3-yl) ethanone
IR (KBr) (nmax, cm”1): 3472, 1665, 1431,
7 ml of 37% aq HCl solution at 0-50C with rapid stirring. 1122, 1072. 1HNMR (300 MHz, DMSO):dH 1.89 (3H,
15 ml of 5 M aq NaNO2 solution was added dropwise s, CH3), 2.42 (3H, s, OCH3), 3.32 (1H, brs, OH), 3.89
to afford yellowish diazonium salts.Then the solution (3H, s, OCH3), 7.72 (1H, s, H4), 7.52-7.89 (7H, Ar
of salicylaldehyde (3-methoxy salicylaldehyde, 0.05 Protons). 13CNMR (75 MHz, DMSO): dC 33.1 (CH3),
mol) in 2% aq KOH solution (100 mL) was added 32.9 (CH3), 59.7 (OCH3), 111.1, 113.7, 127.1, 127.9,
very slowly in 1 hour. The mixture was stirred for 30 132.2, 133.8, 135.5, 139.6, 141.1, 149.8, 154.1,
minutes. The brown solid was filtered and washed 155.2, 156.1 (Alkene and Aryl carbons), 200.3
with sufficient water.Finally it was recrystallized from (C=O).
ethanol to get the pure product.
1-(2-Hydroxy-2-methyl-6-(p-tolyldiazenyl)-2H-
Synthesis of 1-(2-Hydroxy-2-methyl-6 chromene-3-yl) ethanone (2c)
(phenyldiazenyl)-2H-chromene-3-yl) ethanone
(2a)
IR (KBr) (nmax, cm”1): 3383, 1664, 1422,
1142, 1077. 1HNMR (250 MHz, DMSO):dH 1.85 (3H,
Inthemixtureof5-phenylazo-salicylaldehide s, CH3), 2.42 (3H, s, CH3), 2.85 (3H, s, CH3), 3.1 (1H,
1a (1.13 g, 5 mmol) and acetylacetone (0.52 g, brs, OH), 7.10 (1H, d, J = 9 Hz, H8), 7.36 (2H, d, J =
5 mmol) in 25 ml solvent (CH2Cl2/EtOH; 2:1), the 8 Hz, H10), 7.81 (2H, d, J = 7.75 Hz, H9), 7.91-7.93
catalyst Cu-SBA-15 (5 mol%) was added under (2H, m, H4,7), 8.03 (1H, d, J = 2.5 Hz, Hb). 13CNMR

KAMAzANI et al, Orient. J. Chem., Vol. 32(5), 2543-2548 (2016)
2545
(62 MHz, DMSO): dC 25.7 (CH3), 32.9 (CH3), 33.2
(CH3), 110.8, 123.0, 125.1, 126.9, 128.2, 132.6,
134.0, 135.5, 139.8, 140.3, 149.7, 156.5, 160.7
(Alkene and Aryl carbons), 201.9 (C=O).
= 8.7 Hz, H8), 7.32 (1H, d, J = 8.1 Hz, H10), 7.58-
7.90 (4H, m, Ar Protons), 7.99 (1H, d, J = 1.2 Hz,
H5). 13CNMR (75 MHz, DMSO): dC 22.1 (CH3), 22.3
(CH3), 33.5 (CH3), 33.9 (CH3), 111, 119.5, 120.4,
122.5, 125.7, 127.3, 128.5, 132.6, 133.7, 135,
139.3, 139.7, 148.9, 156.1, 160.2 (Alkene and Aryl
carbons), 201.1 (C=O).
1-(6-((4-ethylphenyl)diazenyl)-2-hydroxy-2-
methyl-2H-chromene-3-yl) ethanone (2d)
IR (KBr) (nmax, cm-1): 3291, 1654, 1411,
1
1141, 1078. HNMR (250 MHz, DMSO): dH 1.23
1-(6-((4-ethylphenyl)diazenyl)-2-hydroxy-8-
methoxy-2-methyl-2H-chromene-3-yl) ethanone
(2f)
(3H, t, J = 7.5 Hz, CH3), 1.87 (3H, s, CH3), 2.44
(3H, s, CH3), 2.70 (2H, q, J = 7.5 Hz, CH2), 3.1 (1H,
brs, OH), 7.10 (1H, d, J = 8.75 Hz, H8), 7.42 (2H,
d, J = 8.25 Hz, H10), 7.79 (2H, d, J = 8.25 Hz, H9),
7.90-7.94 (2H, m, H4,7), 8.03 (1H, d, J = 2.25 Hz, H5).
13CNMR (62 MHz, DMSO):dC 16.3 (CH2), 30.6 (CH3),
32.6 (CH3), 32.8 (CH3), 111.5, 122.2, 124.6, 126.8,
128.7, 132.0, 133.8, 135.5, 140, 140.5, 150.4, 156.1,
159.9 (Alkene and Aryl carbons), 201.7 (C=O).
IR (KBr) (nmax, cm-1): 3456, 1662, 1401,
1
1127, 1076. HNMR (300 MHz, DMSO): dH 1.21
(3H, t, J = 7.5 Hz, CH3), 1.89 (3H, s, CH3), 2.42 (3H,
s, CH3), 2.68 (2H, q, J = 7.8 Hz, CH2), 3.3 (1H, brs,
OH), 3.88 (3H, s, OCH3), 7.40 (2H, d, J = 8.1 Hz,
H10), 7.53 (1H, d, J = 1.8 Hz, H7), 7.69 (1H, d, J =
1.8 Hz, H5), 7.78 (2H, d, J = 8.1 Hz, H9), 7.87 (1H,
s, H4).
1-(6-((3,4-dimethylphenyl)diazenyl)-2-hydroxy-2-
methyl-2H-chromene-3-yl) ethanone (2e)
IR (KBr) (nmax, cm”1): 3444, 1659, 1440,
1165, 1079. HNMR (300 MHz, DMSO): dH 1.86
(3H, s, CH3), 2.28 (3H, s, CH3), 2.30 (3H, s, CH3),
RESULTS AND DISCUSSION
1
Diazotization of substituted aniline and a
coupling reaction with 2-hydroxybenzaldehyde or
its derivative (3-methoxysalicylaldehyde) yielded
2.42 (3H, s, CH3), 3.4 (1H, brs, OH), 7.08 (1H, d, J
OH
R'
CHO
OH
NH2
R
R'
CHO
HCl, H2O
N
NaNO2, KOH, 0 0C
N
R
1
Scheme 1: Synthesis of 5-phenylazo-salicylaldehyde derivatives
O
O
SBA-Cu
O
Cu-SBA-15 (5 mol%)
O
N
N
CH2Cl2/EtOH (2:1) , 0 0C
N
H
N
O
H
R
R
OH
N
CHO
OH
O
O
N
R
R'
R'
OH
2
1
R'
a) R = H, R' = H;
d) R = 4-Et, R' = H;
b) R = H, R' = OMe;
e) R = 3,4-Me, R' = H;
c) R = 4-Me, R' = H;
f) R = 4-Et, R'= OMe
Scheme 2: Synthesis of azo-chromene dyes

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KAMAzANI et al, Orient. J. Chem., Vol. 32(5), 2543-2548 (2016)
the corresponding 5-phenylazo-salicylaldehyde
(Scheme 1).
10
9
Previously, an easy and rapid method for
4
5
N
preparation of some 2H-chromene compounds was
published36 and now we explain a simple and high
efficiency pathway for the synthesis of azotated
2H-chromene (2), a novel class of dyes, using
mesoporous Cu-SBA-15 as nanocatalyst (Scheme
N
O
H
R
7
O
O
8
R'
Fig. 1: Number of carbon atoms for structure 2
Table 1 :Yields, mps and Elemental Analysis of 2a–f
Cmpd Yields(%)
mp(0C)
Elemental Analysis (Found)
Formula (M.W.)
C
H
N
2a
2b
2c
2d
2e
2f
88
83
85
79
81
76
134-136
141-143
128-130
121-123
145-147
152-154
70.12(70.11)
67.44(67.43)
70.79(70.77)
71.41(71.44)
71.41(71.40)
68.84(68.81)
5.23(5.19)
5.36(5.31)
5.63(5.55)
5.99(5.97)
5.99(5.95)
6.05(5.99)
9.09(9.02) C18H16N2O3(308.33)
8.28(8.30) C19H18N2O4(338.36)
8.69(8.65) C19H18N2O3(322.36)
8.33(8.32) C20H20N2O3(336.38)
8.33(8.30) C20H20N2O3(336.38)
7.65(7.59) C21H22N2O4(366.41)
for polarizing carbonyl groups in both reagents,
acetylacetone and 5-phenylazo-salicylaldehyde 1,
via the nonbonding electrons on their oxygens.This
coordination is more important for acetylacetone
because it can lead the equilibrium to enol substance
in a suitable solvent.
2). Knoevenagel condensation of compound 1 with
acetylacetone yielded compounds 2a–2f.
The structures of the new azo chromene
dyes were deduced from their IR, 1HNMR, 13CNMR
spectra, and also CHN analysis data. The 1H
decoupled 13CNMR spectrum for each derivate is
completely coincident with the product structure.
Due to low solubility, we could not provide 13CNMR
spectra for 2f compound.
Since b-dicarbonyl compounds such as
acetylacetone have keto-enol tautomerization, less
polar solvents will move the equilibrium toward
the enol form. In examine about effect of solvents,
better yields were observed by using mixture of
dichloromethane and low amount of a protic solvent.
2:1 volume ratio of dichloromethane and ethanol
was most suitable according to the high yields
(Table 1).
Fig.1 illustrates the number of carbon atoms
for structure 2. It is helpful for 1HNMR interpretation
in spectral data section.
The infrared spectra (IR) of these 2H-
chromene dyes show a decreasing intense carbonyl
bands due to conjugated carbonyl systems appearing
at 1650–1670 cm-1. The broad bands in region of
3250–3480 cm”1 are referred to n (O–H) vibrations.
The peaks appearing at 1000–1200 cm-1 are
attributed to n (C–O) aromatic and aliphaticstretching
vibration. The spectra also exhibit the existence of
(–N=N–) group at 1400–1450 cm-1.
The effect of temperature was also
examined. When the reaction warm up to room
temperature or higher, the efficiency will decrease.
So using ice bath is necessary in whole of the
reaction.
CONCLUSIONS
In summary, a new series of azo-chromene
To explain the reaction mechanism, should
dyes 2a–f were synthesized by use of mesoporous
focus on catalyst. The catalyst has lewis acid sites

KAMAzANI et al, Orient. J. Chem., Vol. 32(5), 2543-2548 (2016)
2547
nanocatalyst, Cu-SBA-15, leading short reaction
times, very simple methodology, high efficiency,
easy purification, minimal production of waste
and performing reactions in the mild conditions.
However, the diverse characteristics of these azo
dye compounds need further investigations.
ACKNOWLEDGMENTS
We gratefully acknowledge financial
supports from the University of Tehran.
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