Novel Synthetic Monothiourea Aspirin Derivatives Bearing Alkylated Amines as Potential Antimicrobial Agents

Article abstract of DOI:10.1155/2017/2378186

A new series of aspirin bearing alkylated amines moieties 1-12 were synthesised by reacting isothiocyanate with a series of aniline derivatives in overall yield of 16-56%. The proposed structures of all the synthesised compounds were confirmed using elemental analysis, FTIR, and ¹H and ¹³C NMR spectroscopy. All compounds were evaluated for antibacterial activities against E. coli and S. aureus via turbidimetric kinetic and Kirby Bauer disc diffusion method. Compound 5 bearing meta -CH₃ substituent showed the highest relative inhibition zone diameter against tested bacteria compared to ortho and para substituent. Furthermore, aspirin derivatives bearing shorter chains exhibited better bacterial inhibition than longer alkyl chains.

Full text of DOI:10.1155/2017/2378186

Hindawi
Journal of Chemistry
Volume 2017, Article ID 2378186, 7 pages
https://doi.org/10.1155/2017/2378186
Research Article
Novel Synthetic Monothiourea Aspirin Derivatives Bearing
Alkylated Amines as Potential Antimicrobial Agents
Norsyafikah Asyilla Nordin,1 Tchan Wei Chai,1 Bee Ling Tan,1 Ching Liang Choi,1
Ainaa Nadiah Abd Halim,1 Hasnain Hussain,2 and Zainab Ngaini1
1Department of Chemistry, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak,
94300 Kota Samarahan, Sarawak, Malaysia
2Department of Molecular Biology, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak,
94300 Kota Samarahan, Sarawak, Malaysia
Correspondence should be addressed to Zainab Ngaini; nzainab@unimas.my
Received 19 August 2016; Revised 4 November 2016; Accepted 5 December 2016; Published 22 January 2017
Academic Editor: Artur M. S. Silva
Copyright © 2017 Norsyafikah Asyilla Nordin et al. is is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
A new series of aspirin bearing alkylated amines moieties 1–12 were synthesised by reacting isothiocyanate with a series of aniline
derivatives in overall yield of 16–56%. e proposed structures of all the synthesised compounds were confirmed using elemental
analysis, FTIR, and 1H and 13C NMR spectroscopy. All compounds were evaluated for antibacterial activities against E. coli and
S. aureus via turbidimetric kinetic and Kirby Bauer disc diffusion method. Compound 5 bearing meta -CH substituent showed
3
the highest relative inhibition zone diameter against tested bacteria compared to ortho and para substituent. Furthermore, aspirin
derivatives bearing shorter chains exhibited better bacterial inhibition than longer alkyl chains.
1. Introduction
We have previously reported on aspirin with thiourea
moieties bearing amino acid and aromatic amines with excel-
lent antibacterial properties. e lipophilicity of the aromatic
ring has contributed to the enhancement of the biological
activities [5]. iourea is a type of reactive precursor due to
the presence of C=S, C=O, and NH moieties which are essen-
tial in biological activities [10]. Several biological activities
reported on thiourea are antibacterial, antifungal, anticancer,
antitubercular, antimicrobial, and anti-HIV activities [11–17].
e synthesis of thiourea derivatives has also received great
attraction due to their diverse application such as in textile
processing and heavy metals extraction as chelating agent and
agriculture as plant growth regulator [18–20].
Over the centuries many antibacterial drugs were used to
treat bacterial-causing diseases including food poisoning,
pneumonia and intestinal infection [1, 2]. e improper usage
of these drugs has caused the bacteria to evolve into drug
resistant bacteria which reduce the effectiveness of the drugs
[3]. e continuing development of new antimicrobial agents
therefore remains a priority [1].
Aspirin is a widely used medicine for antipyretic, anal-
gesic, and anti-inflammatory [4]. e demand of aspirin
and its derivatives for other biological properties is increas-
ing due to its availability and reactivity as precursor for
further modification via corresponding carboxyl group
[5]. Aspirin derivatives have shown antibacterial activi-
ties against Bacillus subtilis, Escherichia coli, Staphylococcus
aureus, and Pseudomonas aeruginosa [6, 7]. Other significant
biological properties of aspirin derivatives are reported for
antitumor, anticancer, antifungal, and antimicrobial agents
[5, 7–9].
2. Results and Discussion
Aspirin derivatives 1–12 with aryl side chain bearing alkyl
substituents were prepared from the reaction of acetoxyben-
zoyl isothiocyanate with a series of commercially available

2
Journal of Chemistry
R2
R1
R3
R4
NH2
S
O
O
O
O
O
O
O
O
O
Cl
Cl
DMF
K+SCN−
Cl
Dry acetone
R
S
OH
O
N
N
N
H
H
Dry acetone,
reflux
R5
O
O
O
O
1–12
R1
R2
R3
R4
R5
Compounds
-CH3
-CH3
-CH3
-CH3
-H
-CH3
-H
1
2
-H
-CH3
-H
-H
-H
-H
3
-H
-H
-CH3
-H
-H
-CH3
-H
4
-H
-H
-CH3
-H
-H
-H
5
-OCH3
-H
-H
-OCH3
-H
-H
6
-OCH3
-OCH3
-H
-OCH3
-H
-H
7
-H
-OCH3
-H
-H
8
-OC6H13
-OC10 H21
-OC12H25
-OC14H29
-H
-H
9
-H
-H
-H
-H
10
11
12
-H
-H
-H
-H
-H
-H
-H
-H
Scheme 1: Synthesis of aspirin derivatives 1–12.
methyl and methoxy anilines and alkylated anilines prepared
via Williamson etherification. A general synthesis of 1–12
is depicted in Scheme 1. Characteristic spectroscopic data
of the synthesised compounds are provided in the supple-
mentary data in Supplementary Material available online
at https://doi.org/10.1155/2017/2378186. Aspirin was added
to oxalyl chloride solution in dichloromethane followed
by addition of few drops of dimethylformamide [21]. e
mixture was stirred for 1 h at room temperature and added
dropwise to KSCN in dry acetone to form KCl and filtered
[5]. Aniline derivatives in dry acetone were then added to
the filtrate and refluxed for 4 h. Crushed ice was added to the
mixture to form precipitate. e crude was recrystallised in
ethanol to obtain 1–12 in moderate yields (16–56%). e syn-
thesis of thiourea could form urethane as side product which
contributed to the low product yield [22]. e structures of all
the synthesised compounds were elucidated using elemental
analysis, FTIR, and 1H and 13C NMR spectroscopy.
e FTIR spectra of 1–12 showed absorption bands
at 3375–3213 cm−1 attributed to v(N-H), while peaks cor-
responding to long alkyl chain were observed at 2933–
2843 cm−1. e successful formations of 1–12 were supported
by the disappearance of peak at 2000 cm−1 resulting from the
conversion of -NCS to -NH. e absorption peaks at 1791–
1760 cm−1 and 1675–1611 cm−1 were attributed to v(C=O)
ester and v(C=O) amide, respectively. e aryl groups were
observed at 1528–1500 cm−1. e presence of v(C-N) and
v(C=S) was indicated by the absorption band at 1089–
1125 cm−1 and 890–810 cm−1, respectively [16].
1H NMR spectra of 1–12 showed the presence of methyl
groups at 0.83–2.33 ppm, whereas the methoxy groups were
observed at 3.72–3.96 ppm due to the electronegativity of
oxygen attached to the carbon [23]. e resonance peaks
at 6.42–8.50 ppm were assigned to the aryl groups. e
peaks at 11.53–11.65 ppm and 11.96–12.90 ppm corresponded
to CSNH and CONH, respectively. e deshielding effect
of electron-withdrawing carbonyl group and thiocarbonyl
group has shifed the signal to downfield region [24]. In
13C NMR, methyl substituents were represented at 13.9–
31.9 ppm, while the methoxy group were deshielded at 55.4–
68.2 ppm due to the electronegativity of oxygen [23]. e
presence of peaks at 98.3 and 160.3 ppm was attributed to
aromatic carbons, whereas C=O ester, C=O amide, and C=S
were indicated by the signals at 164.2–166.7 ppm, 168.3–
169.1 ppm, and 176.9–180.0 ppm, respectively. iocarbonyl
and carbonyl group appeared at higher chemical shif due to
formation of intramolecular hydrogen bonding and different
environment and conformations [23, 25].
Prior to the synthesis of 9–12, 13–16 were prepared
as precursors via Williamson etherification of 4-hydroxyl
acetanilide with bromoalkanes in the presence of K CO in
2
3
dry acetone. e mixture was refluxed for 48 h to obtain white

Journal of Chemistry
3
OR
OH
(1) R-Br, K2CO3,
O
acetone
(2) HCl, EtOH
N
H
H2N
13–16
13, R = C6H15
14, R = C10H21
15, R = C12H25
16, R = C14H29
Scheme 2: Preparation of alkylated anilines 13–16.
Table 1: Antibacterial activities of 1–12 in comparison to aspirin and control.
E. coli S. aureus
Compounds
Relative inhibition zone
Relative inhibition zone
Zone of inhibition (mm)
Zone of inhibition (mm)
diameter (%)
diameter (%)
1
2
3
4
7. 3
7. 7
10.5
—
8.0
10.7
—
45.6
48.1
65.6
—
72.7
97.3
—
—
—
5
6
7
8
9
10
10.7
—
8.5
9.3
8.0
—
11.3
—
10.3
10.3
—
66.9
—
53.1
58.1
50.0
—
>100
—
93.6
93.6
—
—
—
11
—
—
—
—
12
—
—
—
—
Aspirin
DMSO
Ampicillin
—
—
16.0
—
—
11.0
—
—
100
—
—
100
precipitate and hydrolysed in ethanol-HCl (1 : 1) to form 13–
16 (Scheme 2) [26–28]. Spectroscopy analysis showed that all
peaks corresponded to the proposed structure.
bacterial surface [10]. e location and type of substituents
in the compounds contribute to the inhibition activities.
Compound 5 with meta substituted -CH gave better inhi-
3
Antibacterial activities of 1–12 were initially performed
against E. coli ATCC 25922 and S. aureus S48/81 via tur-
bidimetric kinetic method [5]. All compounds experienced
solubility limitation in the assays media which hindered the
inhibition studies. Alternatively, disc diffusion method was
performed on 1–12 [29]. Ampicillin (positive control) was
used as standard drug, while dimethyl sulfoxide (DMSO)
was used as negative control with aspirin as a reference.
e antibacterial activities of 1–12 are shown in Table 1.
e inhibition of E. coli and S. aureus was calculated via
inhibition zone of 1–12 in comparison to the inhibition zone
of ampicillin. e inhibition zones of all compounds are
provided in the supplementary data.
bition to the bacterial growth with the highest percentage
relative inhibition zone diameter (66.9%). Compounds 1–
3, 7, and 8 with disubstituted methyl and methoxy group
showed lower inhibition based on zone diameter percentage
(45.6–65.6%). e presence of methyl and methoxy groups
has induced steric repulsion and decreased the activities. e
steric hindrance at both ortho positions in the phenyl group
affected the efficacy of antibacterial effect which explained
that E. coli was insusceptible to 4 [30]. e presence of bulky
methoxy substituents at ortho position in 6 prevented the
compound to act on the active sites of the bacteria [31]. e
introduction of shorter alkyl chain, ꢀ ꢁ = (9), afforded
moderate activity, while no activity was observed for 10–12
with ꢀ ꢁ =0–14. e longer alkyl chain, which is similar to the
component of the cell wall, decreased the penetration onto
the cell membrane [32]. is also suggested that shorter alkyl
chain as in 9 is the optimum length for bacterial inhibition
[27].
In comparison to aspirin, 1–12 showed moderate to good
activities towards the growth of E. coli, except 4, 6, and 10–
12. e presence of C=O, C=S, and NH groups is envis-
aged to contribute to the antibacterial activities and formed
interaction with the carboxyl and phosphate group of the

4
Journal of Chemistry
Antibacterial activities were also demonstrated against
[2-[(2,4-Dimethylphenyl)carbamothioylcarbamoyl]phenyl] Ace-
tate (2). Compound 2 was obtained as yellowish white solid.
Yield: 0. 1117 g (16%); m.p. 115–118∘C; (Found: C, 63.00; H,
5.10; N, 7.88. C H O N S Requires C, 63.14; H, 5.30; N,
S. aureus. Compound 5 gave better inhibition than that of
the standard drug (ampicillin), while 1, 2, 7, and 8 showed
72.7–97.3% inhibition. e presence of a methyl substituent at
meta position in 5 gave better penetration into the bacterial
cell wall via suitable binding [33]. On the other hand, no
activity was observed for 3, 4, 6, and 9–12. Growth inhibition
on S. aureus is lesser compared to E. coli because S. aureus
has thicker cell wall that causes ineffectiveness in membrane
penetration [34].
18 18
3
2
8.18%); v 3381 (N-H), 1775 (C=O ester), 1663 (C=O amide),
1523 (Ar-C), 1189 (C-N), 810 (C=S). ꢂ (DMSO-d ) 2.20 (3H,
6
s, CH ), 2.29 (3H, s, CH ), 2.31 (3H, s,HCH ), 7.04–7.73 (7H, m,
3
3
3
Ar-H), 11.62 (1H, s, NH), 11.96 (1H, s, NH) ꢂ (DMSO-d ) 17.5
6
(CH ), 20.6 (CH ), 20.8 (CH ), 123.2, 126.0,C126.5, 126.8, 130.0,
3
3
3
131.0, 133.2, 133.3, 134.3, 136.5, 148.2 (Ar-C), 166.6 (C=O), 169.0
(C=O) and 179.7 (C=S).
3. Experimental
[2-[(2,5-Dimethylphenyl)carbamothioylcarbamoyl]phenyl] Ace-
tate (3). Compound 3 was obtained as yellowish white solid.
Yield: 0.2620 g (38%); m.p. 119–122∘C; (Found: C, 63.10; H,
5.45; N, 8.02. C H O N S Requires C, 63.14; H, 5.30; N,
Aspirin, oxalyl chloride, potassium thiocyanate, 2,3-dime-
thylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 2,6-di-
methylaniline, 2-toluidine, 2,5-dimethoxyaniline, 3,4-dime-
thoxyaniline, 3,5-dimethoxyaniline, 4-hydroxyl acetanilide,
and 1-bromoalkanes were obtained from Merck. All other
reagents were used without further purification; nevertheless
the acetone was distilled before being used.
Melting points were determined on Stuart SMP3 using
open tube capillary method. FTIR spectra (v/cm−1) were
recorded as KBr pellets on Perkin Elmer 1605 FTIR Spec-
trophotometer. 1H NMR and13C NMR spectra were recorded
on JEOL ECA 500 at 500 MHz (1H) and 125 MHz (13C) with
the chemical shif reported relative to DMSO-d and CDCl
18 18
3
2
8.18%); v 3352 (N-H), 1773 (C=O ester), 1663 (C=O amide),
1524 (Ar-C), 1150 (C-N), 890 (C=S). ꢂ (DMSO-d ) 1.90 (3H,
6
s, CH ), 2.19 (3H, s, CH ), 2.26 (3H,Hs, CH ), 7.03–7.97 (7H,
3
3
3
m, Ar-H), 11.65 (1H, s, NH), 12.22 (1H, s, NH). ꢂ (DMSO-d )
C
6
17.2 (CH ), 20.6 (CH ), 20.8 (CH ), 123.3, 126.1, 126.8, 127.1,
3
3
3
128.0, 130.1, 130.4, 131.4, 133.4, 135.5, 136.7, 148.3 (Ar-C), 166.7
(C=O), 169.1 (C=O) and 179.6 (C=S).
[2-[(2,6-Dimethylphenyl)carbamothioylcarbamoyl]phenyl] Ace-
tate (4). Compound 4 was obtained as yellowish white solid.
Yield: 0.3230 g (47%); m.p. 166–169∘C; (Found: C, 62.77; H,
5.11; N, 8.00. C H O N S Requires C, 63.14; H, 5.30; N,
6
3
as the standard reference and chemical shif values were
expressed in ꢂ ppm.
18 18
3
2
8.18%); v 3386 (N-H), 1784 (C=O ester), 1675 (C=O amide),
1504 (Ar-C), 1176 (C-N), 853 (C=S). ꢂ (DMSO-d ) 2.19 (6H,
H
6
s, 2CH ), 2.31 (3H, s, CH ), 7.12–7.75 (7H, m, Ar-H), 11.64 (2H,
3
3
3.1. General Procedure for the Preparation of Aspirin Bearing
Alkylated Amines (1–12). Aspirin (2 mmol) was added to
oxalyl chloride solution in dichloromethane followed by
addition of few drops of dimethylformamide. e mixture
was stirred for 1 h at room temperature and was added
dropwise to KSCN (2 mmol) in dry acetone (10 mL). e
mixture was stirred at room temperature to form precipitate
and it was filtered to remove the solid. Aryl amine (2 mmol)
in 10 mL of dry acetone was then added to the filtrate and
the reaction mixture was refluxed for 4 h. e mixture was
cooled to room temperature and filtered. e filtrate was
transferred into a beaker and crushed ice was added to it.
e solid formed was recrystallised in ethanol to obtain 1–
12. Supplementary data for FTIR, 1H, and 13C NMR spectra
of the synthesised compounds are available online.
s, NH). ꢂ (DMSO-d ) 17.7 (CH ), 20.7 (CH ), 123.0, 126.0,
C
6
3
3
127.0, 127.5, 128.0, 129.9, 133.2, 135.1, 136.2, 148.1 (Ar-C), 166.4
(C=O), 168.9 (C=O) and 179.9 (C=S).
[2-[(3-Methylphenyl)carbamothioylcarbamoyl]phenyl] Acetate
(5). Compound 5 was obtained as yellow solid. Yield: 0.1177 g
(46%); m.p 179–181∘C; (Found: C, 62.11; H, 4.61; N, 8.28.
C H O N S Requires C, 62.18; H, 4.91; N, 8.53%); v 3382
17 16
3
2
(N-H), 1778 (C=O ester), 1660 (C=O amide), 1500 (Ar-C),
1079 (C-N), 863 (C=S). ꢂ (DMSO-d ) 2.32 (3H, s, CH ), 2.33
(3H, s, CH ), 7.08–7.73 (8HH, m, Ar-H), 11.60 (1H, s, NH), 12.34
6
3
3
(1H, s, NH). ꢂ (DMSO-d ) 20.7 (CH ), 20.9 (CH ), 121.3,
C
6
3
3
123.2, 124.6, 126.6, 127.0, 125.8, 128.5, 130.0, 133.1, 137.7, 138.1,
148.2 (Ar-C), 166.5 (C=O), 168.8 (C=O) and 178.5 (C=S).
[2-[(2,5-Dimethoxyphenyl)carbamothioylcarbamoyl]phenyl]
Acetate (6). Compound 6 was obtained as light green solid.
Yield: 0.1739 g (23%); m.p. 185-186∘C; (Found: C, 57.60; H,
4.40; N, 7.48. C H O N S Requires C, 57.74; H, 4.85; N,
[2-[(2,3-Dimethylphenyl)carbamothioylcarbamoyl]phenyl] Ace-
tate (1). Compound 1 was obtained as a white solid. Yield:
0.2786 g (41%); m.p. 133–136∘C; (Found: C, 62.88; H, 5.30;
N, 7.96. C H O N S Requires C, 63.14; H, 5.30; N, 8.18%);
18 18
5
2
18 18
3
2
7. 4 8%); v 3384 (N-H), 1777 (C=O ester), 1611 (C=O amide),
1500 (Ar-C), 1067 (C-N), 821 (C=S). ꢂ (DMSO-d ) 2.31 (3H,
v 3213 (N-H), 1760 (C=O ester), 1673 (C=O amide), 1525
(Ar-C), 1188 (C-N), 876 (C=S). ꢂ (DMSO-d ) 1.90 (3H, s,
H
6
6
CH ), 2.19 (3H, s, CH ), 2.26 (3H,Hs, CH ), 7.03–7.97 (7H, m,
s, CH ), 3.72 (3H, s, OCH ), 3.84 (3H, s, OCH ), 7.06–8.50
3
3
3
3
3
3
(7H, m, Ar-H), 11.62 (1H, s, NH), 12.90 (1H, s, NH). ꢂ
Ar-H), 11.65 (1H, s, NH), 12.22 (1H, s, NH). ꢂ (DMSO-d )
C
13.9 (CH ), 20.1 (CH ), 20.8 (CH ), 123.2, 124.C9, 125.6, 126.1,
6
(DMSO-d ) 20.7 (CH ), 55.5 (OCH ), 56.6 (OCH ), 108.9,
6
3
3
3
3
3
3
110.5, 112.1, 123.1, 125.9, 126.5, 127.6, 130.1, 133.2, 144.3, 148.2,
152.4 (Ar-C), 166.5 (C=O), 168.8 (C=O) and 177.0 (C=S).
126.8, 128.8, 130.0, 132.5, 133.3, 136.8, 137.4, 148.2 (Ar-C), 166.6
(C=O), 169.0 (C=O) and 180.0 (C=S).

Journal of Chemistry
5
[2-[(3,4-Dimethoxyphenyl)carbamothioylcarbamoyl]phenyl]
Acetate (7). Compound 7 was obtained as dark green solid.
Yield: 0.1801 g (24%); m.p. 182–184∘C; (Found: C, 57.25; H,
4.62; N, 7.42. C H O N S Requires C, 57.74; H, 4.85; N,
6.94–7.73 (8H, m, Ar-H), 11.55 (1H, s, NH), 12.20 (1H, s, NH).
ꢂ (DMSO-d ) 14.0, 20.8, 22.1, 25.5, 28.8, 31.3 (C-H alkyl),
6
6C7.6 (OCH ), 114.3, 123.3, 125.8, 126.6, 130.0, 130.5, 133.1, 148.2,
2
156.9 (Ar-C), 166.4 (C=O), 168.9 (C=O) and 178.6 (C=S).
18 18
5
2
7. 4 8%); v 3367 (N-H), 1791 (C=O ester), 1670 (C=O amide),
1500 (Ar-C), 1025 (C-N), 850 (C=S). ꢂ (DMSO-d ) 2.32
H
6
[2-[((4-(Tetradecyloxy)phenyl)carbamothioyl)carbamoyl]phenyl]
Acetate (12). Compound 12 was obtained as yellowish white
solid. Yield: 0.1240 (47%), m.p. 125–131∘C; (Found: C, 68.08;
H, 8.23; N, 5.31. C H O N S Requires C, 68.41; H, 8.04;
(3H, s, CH ), 3.75 (3H, s, OCH ), 3.77 (3H, s, OCH ),
3
3
3
6.97–7.41 (7H, m, Ar-H), 11.53 (1H, s, NH), 12.24 (1H, s, NH).
ꢂ
(DMSO-d ) 20.8 (CH ), 55.7 (CH ), 108.9, 111.5, 116.6,
C
6
3
3
30 42
4
2
123.4, 126.0, 126.7, 130.1, 130.9, 133.3, 147.2, 148.3, 148.4 (Ar-C),
N, 5.32%); v 3375 (N-H), 2923–2849 (C-H alkyl), 1771 (C=O
ester), 1663 (C=O amide), 1510 (Ar-C), 1111 (C-N), 825 (C=S).
ꢂ (DMSO-d ) 0.83 (3H, t, ꢃ ꢁ =.9 Hz, CH ), 1.22–1.69 (24H,
166.5 (C=O), 169.0 (C=O) and 178.4 (C=S).
[2-[(3,5-Dimethoxyphenyl)carbamothioylcarbamoyl]phenyl]
Acetate (8). Compound 8 was obtained as yellowish white
solid. Yield: 0.4190 g (56%), m.p. 177–179∘C; (Found: C, 57.55;
H, 4.94; N, 7.61. C H O N S Requires C, 57.74; H, 4.85; N,
H
6
3
m, CH ), 2.30 (3H, s, CH ), 3.95 (2H, t, ꢃ ꢁ =.5 Hz, OCH ),
2
3
2
6.94–7.71 (8H, m, Ar-H), 11.53 (1H, s, NH), 12.18 (1H, s, NH).
ꢂ (CDCl ) 14.1, 21.3, 22.7, 26.0, 29.6, 31.9 (C-H alkyl), 68.2
C
3
18 18
5
2
(OCH ), 114.6, 123.9, 124.2, 125.7, 126.8, 130.2, 131.4, 134.4,
7. 4 8%); v 3382 (N-H), 1778 (C=O ester), 1660 (C=O amide),
1528 (Ar-C), 1080 (C-N), 864 (C=S). ꢂ (DMSO-d ) 2.31
2
148.4, 157.9 (Ar-C), 164.2 (C=O), 168.3 (C=O) and 178.3
H
6
(C=S).
(3H, s, CH ), 3.75 (6H, s, 2OCH ), 6.42–7.74 (7H, m, Ar-H),
3
3
11.58 (1H, s, NH), 12.35 (1H, s, NH). ꢂ (DMSO-d ) 20.8
(CH ), 55.4 (2OCH ), 98.3, 102.1, 123.3,C125.9, 126.6, 130.1,
6
3.2. General Procedure for the Preparation of Alkylated Amines
(13–16). 4-Hydroxyl acetanilide (3 mmol) was added to bro-
moalkanes (3 mmol) in the presence of K CO (3 mmol) in
3
3
133.2, 139.4, 148.2, 160.3 (Ar-C), 166.4 (C=O), 168.9 (C=O)
and 178.2 (C=S).
2
3
dry acetone (20 mL). e mixture was refluxed for 48 h to
obtain white precipitate. Sodium hydroxide (2%, 50 mL) was
added and the solid was filtered. e white solid was refluxed
for 4 h in solution of ethanol-HCl (1 : 1) and extracted using
dichloromethane. e organic layer was separated and dried
[2-[((4-(Hexyloxy)phenyl)carbamothioyl)carbamoyl]phenyl]
Acetate (9). Compound 9 was obtained as yellowish white
solid. Yield: 0.2070 g (55%), m.p. 112–119∘C; (Found: C, 63.68;
H, 6.15; N, 6.91. C H O N S Requires C, 63.75; H, 6.32; N,
22 26
4
2
to form 13–16. Supplementary data for FTIR, H, and 13C
1
6.76%); v 3372 (N-H), 2933–2856 (C-H alkyl), 1775 (C=O
ester), 1663 (C=O amide), 1527 (Ar-C), 1106 (C-N), 829
(C=S). ꢂ (DMSO-d ) 0.87 (3H, t, ꢃ ꢁ 7.3 Hz, CH ), 1.31–1.70
NMR spectra of the synthesised compounds are available
online.
(8H, m,HCH ), 2.31 (3H, s, CH ), 3.96 (2H, t, ꢃ ꢁ =.5 Hz,
6
3
2
3
OCH ), 6.96–7.73 (8H, m, Ar-H), 11.54 (1H, s, NH), 12.18 (1H,
2
4-Hexoxyaniline (13). Compound 13 was obtained as a white
crystals. Yield: 1.828 g (75%); m.p. 230–237∘C; v 3408 (N-H),
2934–2866 (-CH), 1517 (Ar-C), 1129 (C-N). ꢂ (DMSO-d )
s, NH). ꢂ (DMSO-d ) 14.0, 20.8, 22.1, 25.2, 28.7, 31.0 (C-H
C
6
alkyl), 67.7 (OCH ), 114.3, 123.3, 126.0, 126.7, 130.1, 130.6,
2
H
6
133.2, 148.3, 157.0 (Ar-C), 166.5 (C=O), 169.0 (C=O) and 178.7
0.86 (3H, t, ꢃ ꢁ =.9 Hz, -CH ), 1.29–1.69 (8H, m, -CH ), 3.87
3
2
(C=S).
(2H, t, ꢃ ꢁ =.5 Hz, -OCH ), 6.84 (2H, d, ꢃ ꢁ 9.2 Hz, Ar-
2
H), 6.91 (2H, d, ꢃ ꢁ 8.4 Hz, Ar-H). ꢂ (DMSO-d ) 13.9, 22.1,
25.2, 28.7, 31.0 (C-H alkyl), 67.9 (OCHC), 115.4, 120.0, 132.4 and
6
[2-[((4-(Decyloxy)phenyl)carbamothioyl)carbamoyl]phenyl]
Acetate (10). Compound 10 was obtained as yellowish white
solid. Yield: 0.2400 (51%), m.p. 116–121∘C; (Found: C, 66.13;
H, 7.44; N, 5.90. C H O N S Requires C, 66.35; H, 7.28;
2
154.4 (Ar-C).
26 34
4
2
N, 5.95%); v 3374 (N-H), 2923–2849 (C-H alkyl), 1771 (C=O
ester), 1664 (C=O amide), 1510 (Ar-C), 1111 (C-N), 826 (C=S).
ꢂ (DMSO-d ) 0.85 (3H, t, ꢃ ꢁ =.9 Hz, CH ), 1.31–1.70 (16H,
4-Decoxyaniline (14). Compound 14 was obtained as a white
crystals. Yield: 2.235 g (80%); m.p. 235–244∘C; v 3427 (N-H),
2921–2849 (-CH), 1513 (Ar-C), 1171 (C-N). ꢂ (DMSO-d )
H
6
3
H
6
m, CH ), 2.31 (3H, s, CH ), 3.96 (2H, t, ꢃ ꢁ =.5 Hz, OCH ),
0.84 (3H, t, ꢃ ꢁ =.9 Hz, -CH ), 1.29–1.70 (16H, m, -CH ),
2
3
2
3
2
6.95–7.73 (8H, m, Ar-H), 11.55 (1H, s, NH), 12.19 (1H, s, NH).
3.93 (2H, t, ꢃ ꢁ =.= Hz, -OCH ), 6.99 (2H, d, ꢃ ꢁ 9.2 Hz,
2
ꢂ (DMSO-d ) 14.0, 20.8, 22.1, 25.5, 28.8, 31.3 (C-H alkyl),
Ar-H), 7.27 (2H, d, ꢃ ꢁ 9.2 Hz, Ar-H), 10.15 (2H, s, -NH ).
6C7.6 (OCH ), 114.3, 123.3, 125.9, 126.6, 130.1, 130.6, 133.2, 148.2,
6
2
ꢂ
(DMSO-d ) 14.1, 22.7, 26.0, 29.5, 31.9 (C-H alkyl), 68.2
2
C
6
156.9 (Ar-C), 166.4 (C=O), 168.9 (C=O) and 178.6 (C=S).
(OCH ), 115.2, 122.3, 124.5 and 159.0 (Ar-C).
2
[2-[((4-(Dodecyloxy)phenyl)carbamothioyl)carbamoyl]phenyl]
Acetate (11). Compound 11 was obtained as yellowish white
solid. Yield: 0.2520 (51%), m.p. 121–124∘C; (Found: C, 67.21;
H, 7.74; N, 5.52. C H O N S Requires C, 67.44; H, 7.68; N,
4-Dodecoxyaniline (15). Compound 15 was obtained as a
white crystals. Yield: 3.050 g (87%); m.p. 237–247∘C; v
3434 (N-H), 2920–2853 (-CH), 1511 (Ar-C), 1171 (C-N). ꢂ
H
28 38
4
3
2
(DMSO-d ) 0.83 (3H, t, ꢃ ꢁ =.9 Hz, -CH ), 1.23–1.71 (20H,
6
2
3
5.62%); v 3374 (N-H), 2923–2843 (C-H alkyl), 1771 (C=O
ester), 1664 (C=O amide), 1510 (Ar-C), 1114 (C-N), 825 (C=S).
ꢂ (DMSO-d ) 0.84 (3H, t, ꢃ ꢁ =.9 Hz, CH ), 1.28–1.68 (20H,
m, -CH ), 3.93 (2H, t, ꢃ ꢁ =.5 Hz, -OCH ), 6.99 (2H, d,
2
2
ꢃ ꢁ 9.2 Hz, Ar-H), 7.30 (2H, d, ꢃ ꢁ 9.2 Hz, Ar-H), 10.27 (2H, s,
-NH ). ꢂ (DMSO-d ) 14.0, 22.1, 25.5, 28.8, 31.3 (C-H alkyl),
H
6
3
2
C
6
m, CH ), 2.31 (3H, s, CH ), 3.96 (2H, t, ꢃ ꢁ =.5 Hz, OCH ),
2
2
67.8 (OCH ), 115.3, 124.1, 124.4 and 158.1 (Ar-C).

6
Journal of Chemistry
4-Tetradecoxyaniline (16). Compound 16 was obtained as
a white crystals. Yield: 2.137 g (50%); m.p. 239–248∘C; v
Competing Interests
e authors declare that there are no competing interests
regarding the publication of this paper.
3410 (N-H), 2919–2853 (-CH), 1512 (Ar-C), 1171 (C-N). ꢂ
H
(DMSO-d ) 0.83 (3H, t, ꢃ ꢁ =.9 Hz, -CH ), 1.23–1.71 (24H,
6
2
3
m, -CH ), 3.94 (2H, t, ꢃ ꢁ =.3 Hz, -OCH ), 7.00 (2H, d,
2
2
ꢃ ꢁ 9.2 Hz, Ar-H), 7.30 (2H, d, ꢃ ꢁ 9.8 Hz, Ar-H), 10.21 (2H, s,
Acknowledgments
-NH ). ꢂ (DMSO-d ) 13.9, 22.1, 25.2, 28.7, 31.0 (C-H alkyl),
2
C
6
e authors would like to thank Universiti Malaysia Sarawak
and Malaysia Ministry of Education for Research Funds
FRGS/ST01(02)/968/2013(09) and FRGS/ST02(01)/1115/2014
(01).
67.9 (OCH ), 115.4, 120.0, 132.4 and 154.4 (Ar-C).
3.3. Antibacterial Studies
3.3.1. Turbidimetric Kinetic Method. e antibacterial activi-
ties of the synthesised compounds were initially studied using
turbidimetric kinetic method against E. coli bacteria ATCC
25922 and S. aureus S48/81. e inoculums were allowed to
grow at 37∘C with permanent stirring at 150 rpm overnight
in Luria-Bertani broth. 0.2 mL of inoculums was inoculated
with 10 mL of culture medium at increasing concentration of
the compounds (50, 80, and 100 ppm) dissolved in DMSO.
e mixtures were shaken at 150 rpm at 37∘C. e inoculum
with only DMSO mixture was used as control. e aliquots
of each replicate were taken at 1 h interval for 6 h. UV/Visible
spectrometer Optima SP-300 was used to analyse the amount
of transmittance (ꢄ). e antibacterial activities of the com-
pounds were determined from the graph as ln ꢅꢀ versus time.
ꢅꢀ is related to the number of colony forming units/mL.
e ln ꢅꢀ values were calculated based on the formula of
ln ꢅꢀ = 27.1–8.56ꢄ (E. coli) and ln ꢅꢀ = 27.4–10.3ꢄ (S. aureus)
[35].
References
¨
[1] Y. G
u¨lkok, T. Bic¸er, F. K. Onurdag˘, S. Ozgen, M. F. S¸ahin, and
D. S. Dog˘ruer, “Synthesis of some new urea and thiourea
derivatives and evaluation of their antimicrobial activities,”
Turkish Journal of Chemistry, vol. 36, no. 2, pp. 279–291, 2012.
[2] E. Rubin and H. M. Reisner, Eds., Essentials of Rubin’s Pathology,
Lippincott Williams & Wilkins, Philadelphia, Pa, USA, 5th
edition, 2009.
[3] R. Richard-Kortum, Biomedical Engineering for Global Health,
Cambridge University Press, Cambridge, Mass, USA, 2010.
[4] K. L. Williamson, Macroscale and Microscale Organic Experi-
ments, Houghton Mifflin, Boston, Mass, USA, 2nd edition, 1994.
[5] Z. Ngaini, M. A. Mohd Arif, H. Hussain, E. S. Mei, D. Tang, and
D. H. A. Kamaluddin, “Synthesis and antibacterial activity of
acetoxybenzoyl thioureas with aryl and amino acid side chains,”
Phosphorus, Sulfur and Silicon and the Related Elements, vol. 187,
no. 1, pp. 1–7, 2012.
[6] A. Lawal and J. A. Obaleye, “Synthesis, characterization and
antibacterial activity of aspirin and paracetamol-metal com-
plexes,” Biokemistri, vol. 19, no. 1, pp. 9–15, 2007.
[7] B. B. Chavan, P. D. Chitte, N. P. Choudhary, K. G. Albhar,
and V. I. Hukkeri, “Synthesis and biological evaluation of novel
benzimidazole derivative with aspirin as potent antimicrobial
& antifungal agents,” International Journal of Scientific Research
and Reviews, vol. 1, pp. 22–30, 2012.
[8] A. Bratasz, K. Selvendiran, T. Wasowicz et al., “NCX-4040, a
nitric oxide-releasing aspirin, sensitizes drug-resistant human
ovarian xenograf tumors to cisplatin by depletion of cellular
thiols,” Journal of Translational Medicine, vol. 6, article 9, 2008.
[9] S. Joseph, T. Nie, L. Huang et al., “Structure-activity relationship
study of novel anticancer aspirin-based compounds,” Molecular
Medicine Reports, vol. 4, no. 5, pp. 891–899, 2011.
[10] Z. Zhong, R. Xing, S. Liu, L. Wang, S. Cai, and P. Li, “Synthesis
of acyl thiourea derivatives of chitosan and their antimicrobial
activities in vitro,” Carbohydrate Research, vol. 343, no. 3, pp.
566–570, 2008.
3.3.2. Disc Diffusion Method. Disc diffusion method was
used due to the insolubility of compounds in medium. E.
coli ATCC 25922 and S. aureus S48/81 were used as ino-
culum where they were cultured in Mueller-Hinton broth
and incubated at 37∘C with permanent shaking at 150 rpm
overnight. e bacterial suspension was then inoculated onto
the entire surface of a Mueller-Hinton agar plate with a sterile
cotton-tipped swab to form an even lawn. Sterile filter paper
disc impregnated with 10 ꢆL of the compound in DMSO was
placed on the surface of agar plate using a sterile pair of
forceps. e plates were then incubated at 37∘C for 24 h. e
zones of inhibition were measured in millimetre (mm) to
estimate the potency of the test compounds [29].
4. Conclusion
[11] A. A. Isab, S. Nawaz, M. Saleem et al., “Synthesis, characteriza-
tion and antimicrobial studies of mixed ligand silver (I) com-
plexes of thioureas and triphenylphosphine; crystal structure
of [Ag(PPh )(thiourea)(NO )] [Ag(PPh )(thiourea)] (NO ) ,”
A series of aspirin derivatives 1–12 with various types of car-
bon substituents were successfully synthesised and demon-
strated against E. coli and S. aureus. e compounds showed
moderate to excellent antibacterial activities compared to
aspirin alone. e substituents at meta position gave better
activity compared to ortho and para position. Aspirin deriva-
tive with shorter chain length showed moderate activity,
compared to the longer alkyl chain. e properties of the
substituents have contributed to the activities and potential
usage in pharmaceutical industries.
3
3
2
3
2
3
2
Polyhedron, vol. 29, no. 4, pp. 1251–1256, 2010.
[12] W. S. H. Wan Zullkiplee, A. N. Abd Halim, Z. Ngaini, M.
A. Mohd Ariff, and H. Hussain, “Bis-thiourea bearing aryl
and amino acids side chains and their antibacterial activities,”
Phosphorus, Sulfur and Silicon and the Related Elements, vol. 189,
no. 6, pp. 832–838, 2014.
[13] R. D. Campo, J. J. Criado, R. Gheorghe et al., “N-benzoyl-
Nꢇ-alkylthioureas and their complexes with Ni(II), Co(III)

Journal of Chemistry
7
and Pt(II)—crystal structure of 3-benzoyl-1-butyl-1-methyl-
thiourea: activity against fungi and yeast,” Journal of Inorganic
Biochemistry, vol. 98, no. 8, pp. 1307–1314, 2004.
[26] N. Cheng, W.-B. Yi, Q.-Q. Wang, S.-M. Peng, and X.-Q. Zou,
“Synthesis and ꢈ-glucosidase inhibitory activity of chrysin,
diosmetin, apigenin, and luteolin derivatives,” Chinese Chemical
Letters, vol. 25, no. 7, pp. 1094–1098, 2014.
[14] S. Saeed, N. Rashid, P. G. Jones, M. Ali, and R. Hussain,
“Synthesis, characterization and biological evaluation of some
thiourea derivatives bearing benzothiazole moiety as poten-
tial antimicrobial and anticancer agents,” European Journal of
Medicinal Chemistry, vol. 45, no. 4, pp. 1323–1331, 2010.
[27] Z. Ngaini, S. M. Haris Fadzillah, and H. Hussain, “Synthesis and
antimicrobial studies of hydroxylated chalcone derivatives with
variable chain length,” Natural Product Research, vol. 26, no. 10,
pp. 892–902, 2012.
[28] T. W. G. Solomons and C. B. Fryhle, Organic Chemistry, John
[15] D. Sriram, P. Yogeeswari, and M. Madhu, “Synthesis and in
vitro antitubercular activity of some 1-[(4-sub)phenyl]-3-
(4-1-[(pyridine-4-carbonyl) hydrazono]ethylphenyl) thiourea,”
Bioorganic & Medicinal Chemistry Letters, vol. 16, pp. 868–878,
2006.
Wiley & Sons, New York, NY, USA, 8th edition, 2004.
[29] L. K. Soni, T. Narsinghani, and R. Jain, “Synthesis and antibacte-
rial screening of some 1-aroyl-3-aryl thiourea derivatives,” ISRN
Medicinal Chemistry, vol. 2014, Article ID 393102, 6 pages, 2014.
[16] A. Saeed, U. Shaheen, A. Hameed, and S. Z. H. Naqvi, “Synthe-
sis, characterization and antimicrobial activity of some new 1-
(fluorobenzoyl)-3-(fluorophenyl)thioureas,” Journal of Fluorine
Chemistry, vol. 130, no. 11, pp. 1028–1034, 2009.
[17] I. Ku¨c¸u¨kgu¨zel, E. Tatar, S¸. G. Ku¨c¸u¨kgu¨zel, S. Rollas, and E. De
Clercq, “Synthesis of some novel thiourea derivatives obtained
from 5-[(4-aminophenoxy)methyl]-4-alkyl/aryl-2,4-dihydro-
3H-1,2,4-triazole-3-thiones and evaluation as antiviral/anti-
HIV and anti-tuberculosis agents,” European Journal of
Medicinal Chemistry, vol. 43, no. 2, pp. 381–392, 2008.
[30] K. Petnapapun, W. Chavasiri, and P. Sompornpisut, “Struc-
ture-activity relationships of 3,3ꢇ-phenylmethylene-bis-4-hy-
droxycoumarins: selective and potent inhibitors of gram-
positive bacteria,” e Scientific World Journal, vol. 2013, Article
ID 178649, 11 pages, 2013.
[31] E. Rodr´ıguez-Ferna´ndez, J. L. Manzano, J. J. Benito, R. Hermosa,
E. Monte, and J. J. Criado, “iourea, triazole and thiadiazine
compounds and their metal complexes as antifungal agents,”
Journal of Inorganic Biochemistry, vol. 99, no. 8, pp. 1558–1572,
2005.
[32] C. R. Birnie, D. Malamud, and R. L. Schnaare, “Antimi-
crobial evaluation of N-Alkyl betaines and N-Alkyl-N,N-
dimethylamine oxides with variations in chain length,” Antimi-
crobial Agents and Chemotherapy, vol. 44, no. 9, pp. 2514–2517,
2000.
[33] J. Li, X. Rao, S. Shang, Y. Gao, and J. Song, “Synthesis and
antibacterial activity of amide derivatives from acrylopimaric
acid,” BioResources, vol. 7, no. 2, pp. 1961–1971, 2012.
[34] J. C. Lopez-Romero, H. Gonza´lez-R´ıos, A. Borges, and M.
Simo˜es, “Antibacterial effects and mode of action of selected
essential oils components against Escherichia coli and Staphylo-
coccus aureus,” Evidence-based Complementary and Alternative
Medicine, vol. 2015, Article ID 795435, 9 pages, 2015.
[35] N. B. Pappano, O. P. Centorbi, and F. H. Ferreti, “Determination
of minimum concentration inhibitory chalcone derivatives,”
Revise Microbiology, vol. 2, pp. 183–188, 1990.
[18] C. Alkan, Y. Tek, and D. Kahraman, “Preparation and character-
ization of a series of thiourea derivatives as phase change mate-
rials for thermal energy storage,” Turkish Journal of Chemistry,
vol. 35, no. 5, pp. 769–777, 2011.
[19] A. M. Alkherraz, Z. I. Lusta, and A. E. Zubi, “Synthesis and use
of thiourea derivative (1-phenyl-3-benzoyl-2-thiourea) for
extraction of cadmium ion,” International Journal of Chemical,
Nuclear, Materials and Metallurgical Engineering, vol. 8, pp. 116–
118, 2014.
[20] C. Kaya, M. Ashraf, and O. So¨nmez, “Promotive effect of
exogenously applied thiourea on key physiological parameters
and oxidative defense mechanism in salt-stressed Zea mays L.
plants,” Turkish Journal of Botany, vol. 39, no. 5, pp. 786–795,
2015.
[21] A. N. Cammidge, S. Downing, and Z. Ngaini, “Surface-func-
tionalised nano-beads as novel supports for organic synthesis,”
Tetrahedron Letters, vol. 44, no. 35, pp. 6633–6634, 2003.
[22] A. R. Katritzky, S. Ledoux, R. M. Witek, and S. K. Nair,
“1-(Alkyl/Arylthiocarbamoyl)benzotriazoles as stable isoth-
iocyanate equivalents: synthesis of Di- and trisubstituted
thioureas,” e Journal of Organic Chemistry, vol. 69, no. 9, pp.
2976–2982, 2004.
[23] R. Rahamathulla, W. M. Khairul, H. Salleh, H. K. Adli, M. I.
N. Isa, and M. G. Tay, “Synthesis, characterization and electro-
chemical analysis of V-shaped disubstituted thiourea-
chlorophyll thin film as active layer in organic solar cells,”
International Journal of Electrochemical Science, vol. 8, no. 3,
pp. 3333–3348, 2013.
[24] S. Saeed, N. Rashid, M. Ali, R. Hussain, and P. G. Jones,
“Synthesis, spectroscopic characterization, crystal structure and
pharmacological properties of some novel thiophene-thiourea
core derivatives,” European Journal of Chemistry, vol. 1, no. 3, pp.
221–227, 2010.
[25] M. S. M. Yusof, R. H. Jusoh, W. M. Khairul, and B. M. Yamin,
“Synthesis and characterisation a series of N-(3,4-dichlo-
rophenyl)-Nꢇ-(2,3 and 4-methylbenzoyl)thiourea derivatives,”
Journal of Molecular Structure, vol. 975, no. 1–3, pp. 280–284,
2010.

International Journal of
Advances in
Organic Chemistry
International
International Journal of
International Journal of
Photoenergy
Medicinal Chemistry
Analytical Chemistry
Physical Chemistry
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
Hindawi Publishing Corporation
http://www.hindawi.com
Volume 2014
Volume 2014
http://www.hindawi.com
Volume 2014
http://www.hindawi.com
Volume 2014
Volume 2014
International Journal of
Carbohydrate
Chemistry
Journal of
Quantum Chemistry
Hindawi Publishing Corporation
Hindawi Publishing Corporation
http://www.hindawi.com
http://www.hindawi.com
Volume 2014
Volume 2014
Submit your manuscripts at
https://www.hindawi.com
Journal of
The Scientific
Analytical Methods
in Chemistry
World Journal
Hindawi Publishing Corporation
Hindawi Publishing Corporation
http://www.hindawi.com
http://www.hindawi.com
Volume 2014
Volume 2014
International Journal of
Journal of
Journal of
International Journal of
Bioinorganic Chemistry
Spectroscopy
Inorganic Chemistry
Electrochemistry
Applied Chemistry
and Applications
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
Hindawi Publishing Corporation
Hindawi Publishing Corporation
Hindawi Publishing Corporation
Volume 2014
http://www.hindawi.com
Volume 2014
http://www.hindawi.com
Volume 2014
http://www.hindawi.com
Volume 2014
http://www.hindawi.com
Volume 2014
Journal of
Journal of
International Journal of
Chromatography
Journal of
Theoretical Chemistry
Research International
Catalysts
Chemistry
Spectroscopy
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Hindawi Publishing Corporation
http://www.hindawi.com
Volume 2014
Volume 2014
Volume 2014
Volume 2014
Volume 2014