86 Periyasamy et al.
Asian J. Chem.
recycled for the next consecutive three batches and isolated
(2).Yield: 0.542 Kg, 99.26 %.
1.8 Hz), 7.78 (d, 1H, ArH, J = 7.8 Hz), 7.69-7.43 (m, 7H,
ArH), 7.02 (d, 2H,ArH, J = 9 Hz). 13C NMR (300 MHz, CDCl3):
δC 166.82, 162.36, 144.96, 138.03, 136.88, 133.81, 132.91,
131.69, 130.05, 129.11, 127.79, 127.73, 123.00, 118.68,
114.46, 111.27, 69.64, 51.92.
IR (neat, cm-1): 1705.62, 1603.86, 1508.90, 1317.76,
1
1282.33, 1250.73, 1166.55, 1104.11. H NMR (300 MHz,
CDCl3): δH 8.02-7.97 (m, 2H, ArH), 6.94-6.89 (m, 2H, ArH)
3.88 (s, 3H, OCH3). 13C NMR (300 MHz, CDCl3): δC 166.87,
163.32, 131.59, 131.19, 122.59, 113.59, 55.41, 51.86.
Methyl-4-ethoxy benzoate (3):To the stirred solution of
methyl paraben (0.100 Kg, 0.657 mol) was treated with diethyl
sulphate (0.152 Kg, 0.98 mol) in the presence of potassium
carbonate (0.181 Kg, 1.31 mol) in 2-butanone (700 mL). Follo-
wed the procedure as mentioned in compound (2) and isolated
the product (3).Yield: 0.118 Kg, 99.64 %.
General procedure for hydrolysis: To the stirred solution
of the ester was prepared above treated with sodium hydroxide
(2.0 eq) in methanol at 60-65 °C for 3 h.Acidified the reaction
mixture with hydrochloric acid and isolated the corresponding
product in good yield and methanol was recovered.
4-Methoxy benzoic acid (7):Yield: 0.540 Kg, 99.67 %.
White solid. m.p.: 183-184.5 °C. IR (neat, cm-1): 1678.79,
1600.24, 1573.84, 1513.92, 1425.40, 1297.25, 1259.13,
1164.26, 1128.89, 1023.86. 1H NMR (300 MHz, DMSO-d6):
δH 7.91-7.868 (m, 2H, ArH), 7.03-6.98 (m, 2H, ArH), 3.81(s,
3H, OCH3). 13C NMR (300 MHz, DMSO-d6): δC166.97,
162.81, 131.70, 131.32, 130.93, 122.81, 113.77, 55.37.
4-Ethoxy benzoic acid (8): Yield: 0.116 Kg, 98.40 %.
White solid. m.p.: 197-200 °C. IR (neat, cm-1): 1673.00, 1606.20,
1577.07, 1299.52, 1259.72, 1172.95, 1114.27, 1042.41,
921.42. 1H NMR (300 MHz, DMSO-d6): δH 7.89-7.85 (m, 2H,
ArH), 7.00-6.97 (m, 2H, ArH), 4.08 (q, 2H, OCH2, J = 6.9
Hz), 1.33 (t, 3H, CH3, J = 6.9 Hz). 13C NMR (300 MHz,
DMSO-d6): δC 166.91, 162.12, 131.32, 122.60, 114.14, 63.39,
14.45.
IR (neat, cm-1): 1712.76, 1605.23, 1510.51, 1314.17,
1
1277.93, 1248.85, 1166.72, 1101.82. H NMR (300 MHz,
CDCl3): δH 8.00-7.95 (m, 2H, ArH), 6.92-6.87 (m, 2H, ArH)
4.07 (q, 2H, OCH2, J = 6.9 Hz), 3.87 (s, 3H, OCH3), 1.41 (t,
3H, CH3, J = 4.5 Hz). 13C NMR (300 MHz, CDCl3): δC 166.90,
162.75, 131.96, 131.57, 131.17, 122.71, 122.36, 114.02, 63.66,
60.59, 51.82, 29.70, 14.67.
Methyl-4-propoxy benzoate (4):To the stirred solution
of methyl paraben (0.200 Kg, 1.31 mol) was treated with
1-bromopropane (0.194 Kg, 1.57 mol) in the presence of
K2CO3 (0.362 Kg, 2.62 mol) in 2-butanone (1400 mL).
Followed the procedure as mentioned in compound 2 and
isolated the product (4). Yield: 0.246 Kg, 96.52 %.
4-Propoxy benzoic acid (9): Yield: 0.243 Kg, 98.90 %.
White solid. m.p.: 144-145.8 °C. IR (neat, cm-1): 1712.91,
1604.02, 1510.38, 1434.16, 1248.53, 1165.57, 1101.89,
IR (neat, cm-1): 1713.00, 1603.95, 1510.33, 1434.11,
1
1248.30, 1165.47, 1101.66, 1012.26, 975.60. H NMR (300
1
MHz, CDCl3): δH 8.00-7.95 (m, 1H,ArH), 6.92-6.87 (m, 1H,
ArH), 3.95 (t, 2H, OCH2, J = 6.6 Hz), 3.87 (s, 3H, OCH3),
1.88-1.76 (m, 2H, CH3-CH2-OCH2), 1.06 (s, 3H, CH3, J = 4.8
Hz). 13C NMR (300 MHz, CDCl3): δC 166.90, 162.94, 131.55,
131.15, 122.30, 113.62, 69.63, 51.80, 22.45, 10.45.
1044.79, 1012.33, 975.66. H NMR (300 MHz, DMSO-d6):
δH 7.89-7.85 (m, 2H, ArH), 7.00 (d, 2H, ArH, J = 7.2 Hz),
3.98 (q, 2H, OCH2-CH2-CH3, J = 6.6 Hz), 1.79-1.67 (m, 2H,-
OCH2-CH2-CH3), 0.970 (t, 3H,-OCH2-CH2-CH3, J = 7.2 Hz).
13C NMR (300 MHz, DMSO-d6): δC 166.92, 162.28, 131.32,
122.61, 114.17, 69.18, 21.86, 10.28.
Methyl 4-[(4-cyanobenzyl)oxy]benzoate (5): To the
stirred solution of methyl paraben (0.200 Kg, 1.31 mol) was
treated with 4-cyanobenzyl bromide (0.309 Kg, 1.57 mol) in
the presence of potassium carbonate (0.362 Kg, 2.62 mol) in
2-butanone (1400 mL). Followed the procedure as mentioned
in compound (2) and isolated the product (5). Yield: 0.342
Kg, 97.34 %. White crystalline solid. m.p.: 148-150 °C.
IR (neat, cm-1): 1708.77, 1607.85, 1513.09, 1434.28,
RESULTS AND DISCUSSION
We initially treated methyl paraben in water in the presence
of sodium hydroxide (2.0 eq) at room temperature afforded
the mixture of products (Scheme-I). Though the reaction was
stirred for 24 h, was obtained 40 % unreacted methyl paraben
(B) and 60 % of the desired corresponding product (A) which
is confirmed by gas chromatography. When treated with
sodium bicarbonate, O-alkylation when compared to potassium
carbonate is too slow and found 15-20 % unreacted methyl
paraben by gas chromatography. When it was stirred in 2-
butanone with potassium carbonate and dimethyl sulphate, it
afforded methyl 4-methoxy benzoate in 99.13 % yield which
upon hydrolysis gave p-anisic acid in 99.67 % yield. 95 % of
2-butanone and methanol were recovered after the process and
recycled for the next three consecutive batches.
1
1319.80, 1260.35, 1165.85, 1107.07. H NMR (300 MHz,
CDCl3): δH 8.03-7.98 (m, 2H, ArH), 7.69 (d, 2H, ArH, J = 8.1
Hz), 7.55 (d, 2H, ArH, J = 8.1 Hz), 7.00-6.95 (m, 2H, ArH),
5.18 (s, 2H, OCH2), 3.89 (s, 3H, OCH3). 13C NMR (300 MHz,
CDCl3): δC 166.65, 161.79, 141.69, 132.50, 131.73, 127.58,
123.42, 118.59, 114.39, 111.98, 68.92, 51.98.
Methyl4-[(2’-cyanobiphenyl-4-yl)methoxy]benzoate
(6):To the stirred solution of methyl paraben (0.200 Kg, 1.31
mol) was treated with 4’-bromomethyl-2-cyano biphenyl
(0.429 Kg, 1.57 mol) in the presence of potassium carbonate
(0.362 Kg, 2.62 mol) in 2-butanone (1400 mL). Followed the
procedure as mentioned in compound (2) and isolated the
product (6).Yield: 0.422 Kg, 93.50 %. White solid. m.p.: 108-
112.5 °C.
COOH
COOH
COOMe
COOMe
+
NaOH/H2O
+
RT/ (CH3)2SO4
OMe
OH
IR (neat, cm-1): 1718.24, 1609.60, 1510.99, 1484.86,
1375.75, 1287.04, 1257.12, 1223.30, 1166.71, 1111.78. 1H
NMR (300 MHz, CDCl3): δH 8.01 (dd, 2H, ArH, J = 6.9 Hz,
OH
OMe
A
C
B
1
Scheme-I