FARMACIA, 2008, Vol.LVI, 6
659
SYNTHESIS OF NEW 2-(4-METHYLPHENOXYMETHYL)BENZOIC ACID
THIOUREIDES
CARMEN LIMBAN1, ALEXANDRU-VASILE MISSIR1, ILEANA
CORNELIA CHIRIŢA1, GEORGE MIHAI NIŢULESCU1, LAURENŢIU
MORUSCIAG1, CAMELIA ELENA STECOZA1, DIANA CAMELIA
NUŢĂ1, CARMELLINA DANIELA BĂDICEANU1, MIRON TEODOR
CĂPROIU2, CONSTANTIN DRĂGHICI2
1
Department of Pharmaceutical Chemistry, University of Medicine and
Pharmacy Carol Davila, Traian Vuia, 6, sect. 2, 020956, Bucharest
2
The Organic Chemistry Center of Romanian Academy "Costin D.
Nenitescu”, Splaiul Independentei, 202B, 77208, Bucharest, Romania
*corresponding author: carmen_limban@yahoo.com
Abstract
In this study were synthesized some new thioureides of the 2-(4-methylphenoxymethyl)-benzoic acid with potential antimicrobial activity and theirs chemical
structures have been confirmed by 1H-NMR, 13C-NMR and IR spectra and by elemental
analysis.
Rezumat
În cadrul acestui studiu am sintetizat noi tioureide ale acidului 2-(4-metilfenoximetil)-benzoic, substanţe cu potenţială acţiune antimicrobiană, ale căror structuri
chimice au fost confirmate de spectrele 1H-RMN, 13C-RMN şi IR, precum şi de analiza
elementală.


thioureides
2-(4-methylphenoxymethyl)benzoic acid
INTRODUCTION
It is well known that many compounds bearing thioureide structure
have been reported to have antimicrobial, antifungal and anthelmintic
activity.
Considering these biological activities, in the previously papers [15] we have presented the synthesis and characterization of some thioureides
of the 2-phenoxymethyl-benzoic acid unsubstituted or substituted with
chloro, methyl or methoxy group and for some of these compounds theirs
antimicrobial activity.
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FARMACIA, 2008, Vol.LVI, 6
Experimental
The 2-(4-methyl-phenoxymethyl)benzoic acid synthesis
A solution containing 0.05 mol of freshly distilled para-cresol in
30 mL xylene was placed in a round-bottom flask, equipped with a water
removing device. Subsequently, 0.055 mol of potassium hydroxide were
added.
The reaction mixture was refluxed until resulting water was
removed by azeotropic distillation, while potassium para-cresolate
precipitated at the bottom.
0.05 Mol of phtalide were added and the mixture was refluxed until
it solidifies.
The precipitate was heated for solubilisation with 10% potassium
hydroxide solution and then it was diluted with 50 mL of water.
The aqueous phase was separated and acidulated with 1M
hydrochloric acid solution until the mixture became acidic (pH 3), when the
2-(4-methyl-phenoxymethyl)benzoic acid precipited. The resulting
precipitate is crystallized from water: ethanol (1: 1) mixture, showing a m.p.
122.5- 125.50C. 7.2 g 2-(4-Methyl-phenoxymethyl)-benzoic acid (Wt
242.26) resulted (59.5% yield).
The 2-(4-methyl-phenoxymethyl)benzoyl chloride synthesis
0.02 Mol of 2-(4-methyl-phenoxymethyl)benzoic acid, 30 mL of
dry 1,2-dichloroethane and 0.042 mol of thionyl chloride were placed in a
round-bottom flask equipped with a condenser and drying tube. The mixture
was refluxed for 3 hours. The excess thionyl chloride and the solvent were
removed by reduced pressure. For the next step the acid chloride was used
in crude status.
1,2-Dichloroethane was anhydrized over calcium chloride and
distillated at normal pressure.
The new thioureides synthesis (general procedure)
To a solution of ammonium thiocyanate (0.01 mol) in 5 mL dry
acetone was added a solution of 2-(4-methyl-phenoxymethyl)-benzoyl
chloride (0.01 mol) in 10 mL dry acetone.
The acetone was dried over potassium carbonate and the
ammonium thiocyanate by heating at 1000C.
The reaction mixture was refluxed one hour in a one round-bottom
flask with a condenser and a drying tube. After cooling, 0.01 mol of dry and
freshly distilled primary aromatic amine in 2 mL dry acetone were added by
stirring to the reaction mixture. The mixture was afterwards refluxed for one
hour. The product was precipitated after the cool reaction mixture was
poured in 500 mL water.
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FARMACIA, 2008, Vol.LVI, 6
The crude thioureides obtained were crystallised from isopropanol
with active carbon.
RESULTS AND DISCUSSION
The synthesis of the new thioureides was performed in three stages.
The 2-(4-methyl-phenoxymethyl)benzoic acid synthesis
In the first step, 2-(4-methyl-phenoxymethyl)benzoic acid (1) was
obtained by treating phtalide (2) with potassium para-cresolate in xylene,
under
reflux.
First
the
potassium
salts
of
2-(4-methylphenoxymethyl)benzoic acid (3) was obtained and, by having a good
solubility in a 10% potasium hydroxide aqueous solution, can be separated
from xylene. The acid 1 was removed from the salts by hydrochloric acid
solution treatment.
The potassium para-cresolate was obtained through the reaction of
para-cresol with potassium hydroxide in xylene reaction medium. The
resulting water was removed by azeotropic distillation.
The reactions are presented in the Scheme 1.
CH2
- +
OK
O + H3C
O
COO K +
CH3
O
2
3
HCl
- KCl
O
CH2
COOH
CH3
1
Scheme 1
The synthesis of 2-(4-methyl-phenoxymethyl)benzoic acid
The 2-(4-methyl-phenoxymethyl)benzoyl chloride synthesis
In the second stage of the synthesis, the 2-(4-methylphenoxymethyl)benzoyl chloride (4) was obtained by reacting for three
hours the acid (1) with thionyl chloride, in 1,2-dichlorethane made anhydric
with calcium chloride. After the removal of the excess reactant and the
reaction medium, the raw acid chloride was used in the next stage.
Scheme 2 presents the mentioned reaction.
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FARMACIA, 2008, Vol.LVI, 6
O
CH2
CH3
COOH
O
CH2
SOCl2
CH3
COCl
4
1
Scheme 2
The synthesis of 2-(4-methyl-phenoxymethyl)benzoyl chloride
The new thioureides synthesis
In the third stage the 2-(4-methyl-phenoxymethyl)benzoyl
chloride was reacted with ammonium thiocyanate, dried at 1000C, and 2-(4methyl-phenoxymethyl)benzoyl isothiocyanate (5) was obtained. The
reaction time was one hour and the reaction medium was acetone dried on
potassium carbonate. The obtained isothiocyanate was not separated and the
new thioureides (6a-g) resulted after adding the corresponding primary
aromatic amines in the reaction medium, while the reflux continued for
another hour.
O
CH2
CH3
C-Cl
O
O
CH2
O
C
NH
6.a. ,
5
CH3
C
NH
6a-g
R
S
O
R=
CH3
C-N=C=S
4
H2N-R
O
CH2
NH4SCN
C3H7-iso 6.c. ,
C3H7-n 6.b. ,
n-H7C3
C4H9-sec 6.e. ,
6.f. ,
C4H9-tert 6.g.
tert-C4H9
Scheme 3
The synthesis of the new thioureides
C4H9-n 6.d.
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FARMACIA, 2008, Vol.LVI, 6
The new thioureides are solid, crystallized, white or light yellow,
soluble at normal temperature in acetone and chloroform and by heating in
inferior alcohols, benzene, toluene and xylene, insoluble in water.
The structure, molecular formula, molecular weight, melting point
and yield of the new thioureides are presented in table I.
Table I
The new compounds characteristics
14 13
8
CH2
4
5
O
9
10 11
3
6
15
CH3
12
R
2
7
1
22 21
16
CO NH C NH
17
18
20
19
S
No.
R
5a.
2 CH2-CH2-CH3
5b.
4 CH2-CH2-CH3
5c.
4 CH(CH3)2
5d.
4 CH2-CH2-CH2-CH3
23
24
23
23
24
23
5e.
25
24
23
4
25
24
25
25
26
Molecular
formula
Molecular
weight
C25H26N2O2S
418.546
C25H26N2O2S
418.546
C25H26N2O2S
418.546
C26H28N2O2S
432.566
C26H28N2O2S
432.566
C26H28N2O2S
432.566
C26H28N2O2S
432.566
26
CH-CH2-CH3
24
CH3
23 24
5f.
2 C(CH3)3
5g.
4 C(CH3)3
23 24
Melting
point
Yield(%)
(0C)
178.361
182.1
143.467
147.9
14473
147.3
84.371
87.6
111.7114.9
115.8118.6
126.4128.3
78
62
74
The melting points were determined at an Electrothermal 9100
apparatus and were uncorrected.
The elemental analysis of the newly obtained compounds was
performed with a Perkin Elmer CHNS/O Analyser Series II 2400 apparatus.
The calculated formula provided by the elemental analysis results
(table II) is in good agreement with the expected structures.
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FARMACIA, 2008, Vol.LVI, 6
Table II
The elemental analysis
CH2
O
CH3
R
C-NH-C-NH
O
Nr.
crt.
5a.
5b.
5c.
5d.
5e.
5f.
5g.
R
2-C3H7-n
4-C3H7-n
4-C3H7-iso
4-C4H9-n
4-C4H9-sec
2-C4H9-tert
4-C4H9-tert
c.
71.74
71.74
71.74
72.19
72.19
72.19
72.19
C%
e.
71.25
71.33
71.36
72.03
72.31
72.37
72.41
S
c.
6.26
6.26
6.26
6.52
6.52
6.52
6.52
H%
e.
6.21
6.32
6.62
6.50
6.42
6.58
6.66
c.
6.69
6.69
6.69
6.48
6.48
6.48
6.48
N%
e.
6.80
6.81
6.84
6.61
6.52
6.60
6.57
c.
7.66
7.66
7.66
7.41
7.41
7.41
7.41
S%
e.
7.69
7.80
7.60
7.55
7.47
7.55
7.52
where: c = calculated, e = experimental
Spectral data
1
H-NMR Spectra were performed at 300 MHz and those of 13CNMR were recorded at 75 MHz, using a Varian Gemini 300BB equipment,
hexadeuterodimethylsulfoxid (CD3)2SO as solvent. Chemical shifts were
recorded as δ values in parts per milion (ppm) relative with
tetramethylsilane, Si(CH3)4, as internal standard. Multiplicities are given
together with coupling constants in Hz. For unambiguous assignment 1Hdecoupling COSY 1H-1H and COSY 1H-13C were used.
The molecular structure of the new compounds, deduced from the
equations of the synthesis reactions, is confirmed by the values of the
absorbtion bands from the IR spectra, collected with a FT-IR Bruker Vertex
70 spectrometer.
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(2-propylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.23(bs, 1H, NH); 11.91(bs, 1H, NH);
7.63(dd, 1H, H-7, 1.2, 7.2); 7.56(m, 2H, H-4, H-6); 7.47(td, 1H, H-5, 7.1,
2.2); 7.30÷7.21(m, 4H, H-19-20-21-22); 7.06(d, 2H, H-11-13, 8.4); 6.87(d,
2H, H-10-14, 8.4); 5.25(s, 2H, H-8); 2.50(t, 2H, H-23); 2.21(s, 3H, H-15);
1.47(sxt, 2H, H, 24, 7.6); 0.79(t, 3H, H-25, 7.6).
13
C-NMR(dmso-d6, δ ppm): 180.09(C-16); 170.37(C-1); 156.04(C-9);
146.01(C-18); 137.04(Cq); 136.16(Cq); 135.58(Cq); 129.53(Cq); 130.87(C-
FARMACIA, 2008, Vol.LVI, 6
665
7); 129.69(C-11-13); 129.65(CH); 128.53(C-4); 128.40(C-5); 127.71(C-6);
126.90(CH); 126.87(CH); 125.91(CH); 114.45(C-10-14); 67.48(C-8);
32.80(C-23); 22.88(C-24); 19.97(C-15); 13.51(C-25).
FT-IR(ATR in solid, ν cm-1): 3160m; 3027m; 2959m; 2930m; 2869m;
1666m; 1610w; 1584w; 1510vs; 1449m; 1386m; 1329m; 1290m; 1263m;
1243vs; 1196m; 1160s; 1118m; 1073w; 1046m; 946w; 855w; 814w; 796w;
741m; 688w; 606w; 570w; 506w; 455w; 422w.
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(4-propylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.27(bs, 1H, NH); 11.74(bs, 1H, NH);
7.62(dd, 1H, H-7, 1.2, 7.2); 7.60÷7.42(m, 3H, H-4-5-6); 7.49(d, 2H, H-1822, 8.5); 7.21(d, 2H, H-19-21, 8.5); 7.06(d, 2H, H-11-13, 8.6); 6.87(d, 2H,
H-10-14, 8.6); 5.26(s, 2H, H-8); 2.53(t, 2H, H-23, 7.1); 2.20(s, 3H, H-15);
1.60(sxt, 2H, H-24, 7.1); 0.91(t, 3H, H-25, 7.1).
13
C-NMR(dmso-d6, δ ppm): 178.70(C-16); 170.12(C-1); 156.04(C-9);
140.52(C-20); 135.73(Cq); 135.56(Cq); 133.37(Cq); 129.58(Cq); 130.84(C7); 129.71(C-11-13); 128.41(C-4); 128.33(C-5); 128.20(C-6); 127.58(C-1921); 123.86(C-18-22); 114.56(C-10-14); 67.46(C-8); 36.67(C-23); 23.87(C24); 19.97(C-15); 13.51(C-25).
FT-IR(ATR in solid, ν cm-1): 3322w; 3156w; 3037m; 2957w; 2923w;
2866w; 1670m; 1597m; 1507vs; 1443m; 1415m; 1379m; 1343m; 1293m;
1226s; 1176m; 1146s; 1084m; 1030m; 945w; 846w; 829w; 799w; 748m;
735m; 665w; 638w; 602w; 558w; 517w; 420w.
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(4-isopropylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.38(bs, 1H, NH); 11.80(bs, 1H, NH);
7.61(dd, 1H, H-7, 1.2, 7.2); 7.60÷7.42(m, 3H, H-4-5-6); 7.50(d, 2H, H-1822, 8.3); 7.27(d, 2H, H-19-21, 8.3); 7.06(d, 2H, H-11-13, 8.6); 6.87(d, 2H,
H-10-14, 8.6); 5.26(s, 2H, H-8); 2.88(spt, 1H, H-23, 7.0); 2.21(s, 3H, H-15);
1.21(d, 6H, H-24, 7.0).
13
C-NMR(dmso-d6, δ ppm): 178.86(C-16); 170.19(C-1); 156.13(C-9);
146.50(C-20); 135.80(Cq); 135.57(Cq); 133.34(Cq); 129.69(Cq); 131.00(C7); 129.81(C-11-13); 128.51(C-4); 128.35(C-5); 127.73(C-6); 126.42(C-1921); 124.22(C-18-22); 114.59(C-10-14); 67.51(C-8); 33.03(C-23); 23.82(C24); 20.08(C-15).
FT-IR(ATR in solid, ν cm-1): 3339w; 3037w; 2961m; 2921w; 2866w;
1673m; 1595m; 1555m; 1509vs; 1416w; 1380w; 1347m; 1286m; 1223s;
1176w; 1144s; 1121m; 1031m; 946w; 855w; 826m; 803w; 776w; 750m;
669w; 639w; 603w; 536w; 519w; 432w.
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FARMACIA, 2008, Vol.LVI, 6
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(4-n-butylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.39(bs, 1H, NH); 11.79(bs, 1H, NH);
7.62(dd, 1H, H-7, 1.2, 7.2); 7.61÷7.40(m, 3H, H-4-5-6); 7.49(d, 2H, H-1822, 8.1); 7.22(d, 2H, H-19-21, 8.1); 7.05(d, 2H, H-11-13, 8.6); 6.88(d, 2H,
H-10-14, 8.6); 5.26(s, 2H, H-8); 2.58(t, 2H, H-23, 7.5); 2.21(s, 3H, H-15);
1.56(qv, 2H, H-25, 7.5); 1.31(sxt, 2H, H-25, 7.5); 0.91(t, 3H, H-26, 7.5).
13
C-NMR(dmso-d6, δ ppm): 178.80(C-16); 169.54(C-1); 156.13(C-9);
140.50(C-20); 135.82(Cq); 135.67(Cq); 133.34(Cq); 129.67(Cq); 130.99(C7); 129.81(C-11-13); 128.51(C-4); 128.34(C-5); 127.71(C-6); 128.38(C-1921); 124.08(C-18-22); 114.60(C-10-14); 67.51(C-8); 34.35(C-23); 33.04(C25); 21.73(C-24); 20.07(C-15); 13.76(C-26).
FT-IR(ATR in solid, ν cm-1): 3320m; 3249s; 3025m; 2950s; 2930s; 2867m;
1691m; 1661m; 1597vs; 1530vs; 1508vs; 1361vs; 1292m; 1262s; 1216s;
1174m; 1150s; 1082m; 1013m; 961w; 852w; 817m; 800m; 762m; 734s;
653w; 638w; 613w; 532w; 510w; 459w.
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(4-sec-butylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.21(bs, 1H, NH); 11.76(bs, 1H, NH);
7.62(dd, 1H, H-7, 1.2, 7.2); 7.61÷7.40(m, 3H, H-4-5-6); 7.52(d, 2H, H-1822, 8.5); 7.23(d, 2H, H-19-21, 8.5); 7.05(d, 2H, H-11-13, 8.6); 6.88(d, 2H,
H-10-14, 8.6); 5.26(s, 2H, H-8); 2.61(sxt, 1H, H-23, 7.0); 2.20(s, 3H, H-15);
1.56(qv, 2H, H-25, 7.0); 1.20(d, 3H, H-24, 7.0); 0.78(t, 3H, H-26, 7.0).
13
C-NMR(dmso-d6, δ ppm): 178.63(C-16); 170.06(C-1); 156.05(C-9);
145.16(C-20); 135.72(Cq); 135.51(Cq); 133.25(Cq); 129.59(Cq); 130.89(C7); 129.70(C-11-13); 128.39(C-4); 128.34(C-5); 127.62(C-6); 126.89(C-1921); 123.92(C-18-22); 114.53(C-10-14); 67.46(C-8); 40.36(C-23); 30.41(C25); 21.52(C-24); 19.97(C-15); 11.93(C-26).
FT-IR(ATR in solid, ν cm-1): 3324m; 3157w; 3034w; 2962m; 2917w;
2869w; 1674m; 1599m; 1508vs; 1446m; 1416w; 1380w; 1341m; 1292w;
1261m; 1224s; 1176w; 1142s; 1087w; 1029m; 959w; 857w; 828m; 802w;
748w; 670w; 603w; 539w; 518w.
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(2-tert-butylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.27(bs, 1H, NH); 11.96(bs, 1H, NH);
7.62(dd, 1H, H-7, 1.3, 6.9); 7.55÷7.40(m, 3H, H-4-5-6), 7.27÷7.22(m, 4H,
H-19-20-21-22); 7.08(d, 2H, H-11-13, 8.4); 6.86(d, 2H, H-10-14, 8.6);
5.25(s, 2H, H-8); 2.21(s, 3H, H-15); 1.24(s, 9H, H-24).
13
C-NMR(dmso-d6, δ ppm): 180.95(C-16); 170.83(C-1); 156.20(C-9);
145.18(C-17); 136.20(Cq); 135.63(Cq); 133.55(Cq); 131.17(CH); 130.98(C7); (C-7); 129.90(C-11-13); 129.81(Cq); 129.03(CH); 128.57(C-4);
FARMACIA, 2008, Vol.LVI, 6
667
128.05(C-5); 127.65(C-6); 126.75(CH); 126.34(CH); 114.65(C-10-14);
67.62(C-8); 34.48(C-23); 30.51(C-24); 20.14(C-15).
FT-IR(ATR in solid, ν cm-1): 3334w; 3155w; 3032w; 2963w; 2872w;
1672m; 1607m; 1504vs; 1390m; 1326m; 1287m; 1222s; 1144s; 1035m;
948w; 856w; 825m; 792m; 743m; 678w; 608w; 557w; 518w; 480w.
N-[2-(4-Methylphenoxymethyl)-benzoyl]-N’-(4-tert-butylphenyl)-thiourea
1
H-NMR(dmso-d6, δ ppm, J Hz): 12.28(bs, 1H, NH); 11.78(bs, 1H, NH);
7.62(dd, 1H, H-7, 1.2, 7.2); 7.61÷7.40(m, 3H, H-4-5-6); 7.53(d, 2H, H-1822, 8.7); 7.42(d, 2H, H-19-21, 8.7); 7.06(d, 2H, H-11-13, 8.6); 6.88(d, 2H,
H-10-14, 8.6); 5.27(s, 2H, H-8); 2.20(s, 3H, H-15); 1.29(s, 9H, H-24).
13
C-NMR(dmso-d6, δ ppm): 178.70(C-16); 170.07(C-1); 156.05(C-9);
148.60(C-20); 135.74(Cq); 135.24(Cq); 133.30(Cq); 129.61(Cq); 130.87(C7); 129.70(C-11-13); 128.41(C-4); 128.24(C-5); 127.59(C-6); 125.21(C-1921); 123.65(C-18-22); 114.55(C-10-14); 67.47(C-8); 34.19(C-23); 31.24(C24); 19.98(C-15).
FT-IR(ATR in solid, ν cm-1): 3369w; 3145w; 3036w; 2962m; 2869w;
1675m; 1588m; 1538s; 1509vs; 1443m; 1381w; 1337m; 1291w; 1261w;
1227s; 1177w; 1145s; 1051w; 1027m; 946w; 828m; 799w; 739m; 692w;
665w; 597w; 548w; 515w; 497w; 448w.
The chemical structure of the synthesized compounds has been
confirmed by elemental analysis, IR and NMR spectroscopy.
CONCLUSIONS
We have synthesized seven new compounds, thioureides of the 2(4-methyl-phenoxymethyl)benzoic acid. The synthesis involves three stages:
1) the synthesis of 2-(4-methyl-phenoxymethyl)benzoic acid; 2) the
synthesis of 2-(4-methyl-phenoxymethyl)benzoyl chloride; 3) the synthesis
of the new thioureides. The structure was confirmed by spectrophotometric
methods (FT-IR and NMR) and by elemental analysis. The obtained
thioureides will be further investigated to determinate their antimicrobial
activity.
Acknowledgements
The authors acknowledge support for this work from the Romanian
Ministry of Education, Research and Youth through project PN2 41043/2007.
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FARMACIA, 2008, Vol.LVI, 6
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