Synthesis of Hydroxybenzoic Acids and Their Esters by Reaction of Phenols with Carbon Tetrachloride and Alcohols in the Presence of Iron Catalysts

Article abstract of DOI:10.1134/S1070363218020056

Alkyl esters of hydroxy-, methoxy-, and ethoxybenzoic and cresotic acids have been synthesized by reaction of phenols, anisole, phenetole, and cresols with carbon tetrachloride and alcohols in the presence of iron catalysts.

Full text of DOI:10.1134/S1070363218020056

ISSN 1070-3632, Russian Journal of General Chemistry, 2018, Vol. 88, No. 2, pp. 208–215. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © A.R. Bayguzina, L.I. Tarisova, R.I. Khusnutdinov, 2018, published in Zhurnal Obshchei Khimii, 2018, Vol. 88, No. 2, pp. 228–235.
Synthesis of Hydroxybenzoic Acids and Their Esters
by Reaction of Phenols with Carbon Tetrachloride and Alcohols
in the Presence of Iron Catalysts
A. R. Bayguzinaa,b, L. I. Tarisovab, and R. I. Khusnutdinova,b*
a Institute of Petrochemistry and Catalysis, Russian Academy of Sciences,
pr. Oktyabrya 141, Ufa, Bashkortostan, 450075 Russia
*e-mail: inklab4@gmail.com
b Ufa State Petroleum Technological University, ul. Kosmonavtov 1, Ufa, Bashkortostan, 450062 Russia
Received September 4, 2017
Abstract—Alkyl esters of hydroxy-, methoxy-, and ethoxybenzoic and cresotic acids have been synthesized by
reaction of phenols, anisole, phenetole, and cresols with carbon tetrachloride and alcohols in the presence of
iron catalysts.
Keywords: hydroxy- and alkoxybenzoic acids, cresotic acids, salicylic acid, phenols, iron catalysts
DOI: 10.1134/S1070363218020056
Hydroxy- and methoxybenzoic and cresotic acids
and their esters are used in medicine and perfumery
and are components of foods, cosmetics, and
pharmacological agents. They exhibit antiseptic and
anesthetic properties and are used for the treatment of
rheumatism [1].
Therefore, studies are carried out with the goal of
developing efficient alternative methods for the synthesis
of aromatic carboxylic acids and their derivatives.
Komiyama and Hirai [5–8] reported a procedure for
the synthesis of aromatic carboxylic acids from phenols
and carbon tetrachloride in the presence of copper
powder and β-cyclodextrin in alkaline medium. The
reaction occurs in the β-cyclodextrin cavity having a
definite size, and the selectivity for 4-hydroxybenzoic
acid attains ~100%.
The most widely known method of synthesis of
hydroxybenzoic acids is based on carboxylation of
phenols with carbon dioxide under pressure (Kolbe–
Schmitt reaction) [2]. Another method consists of
carboxylation of phenols with metal alkyl carbonates
[3, 4]. The latter are obtained by reaction of carbon
dioxide with alkali metal alkoxides. The use of
gaseous carbon dioxide is associated with large
difficulties in the design of equipment for industrial
processes, which creates serious impediments to wide
implementation of these methods for preparative purposes.
Our study was aimed as synthesizing alkyl esters of
hydroxy-, methoxy-, and ethoxybenzoic and cresotic
acids by reaction of phenol, cresols, anisole, and
phenetole with carbon tetrachloride and alcohols in the
presence of iron salts and complexes. This procedure
was successfully applied previously to naphthalene,
phenanthrene, and thiophene as substrates [9–12].
Scheme 1.
OH
OH
CO2R
OH
CCl4, ROH
+
[Fe], 130oC, 4_8 h
RO2C
2a_2d
3a_3d
1
R = Me (a), Et (b), n-Pr (c), n-Bu (d).
208

SYNTHESIS OF HYDROXYBENZOIC ACIDS AND THEIR ESTERS
209
Scheme 2.
OMe
OMe
CO2R
OMe
CCl4, ROH
+
[Fe], 130oC, 4_8 h
RO2C
4
5a_5d
6a_6d
R = Me (a), Et (b), n-Pr (c), n-Bu (d).
Scheme 3.
OEt
OEt
CO2Pr-n
OEt
CCl4, n-PrOH
FeBr3, 130oC, 6 h
+
n-PrO2C
n-PrO2C
7
8c (24%)
9c (76%)
Scheme 4.
OH
OH
CH3
CH3
10
13c (12%)
OH
OH
CO2Pr-n
Fe2(CO)9, CCl4, n-PrOH
150oC, 6 h
CH3
11
CH3
14c (20%)
OH
OH
n-PrO2C
CH3
CH3
15c (10%)
12
The reaction of phenol 1 with carbon tetrachloride
and aliphatic alcohols (MeOH, EtOH, PrOH, BuOH)
in the presence of an iron catalyst [130°C, 4–8 h, molar
ratio Fe–phenol–CCl4–alcohol = (1–10) : 100 : (100–
1000) : (100–1000)] afforded 2-hydroxybenzoic (salicylic)
and 4-hydroxybenzoic acid esters 2a–2d and 3a–3d
(Scheme 1).
occurred in the absence of a catalyst. The most
efficient catalyst for the alkoxycarbonylation of phenol
was Fe2(CO)9. When the molar ratio Fe2(CO)9–PhOH–
CCl4–PrOH was 5 : 100 : 500 : 500, the conversion of
phenol was 100%, and the yields of propyl esters 2c
and 3c were 34 and 66%, respectively. The quantitative
overall yield of 2c and 3c was achieved in 6 h.
The optimal conditions, including reactant and
catalyst concentrations, were determined using the
reaction of phenol with propan-1-ol and CCl4 as model
reaction. The following iron compounds were tested as
catalysts: FeBr3, FeCl3·6H2O, Fe2(CO)9, FeCl2, FeCl3,
Fe(acac)3, FeCl2·4H2O] (Table 1). No reaction
Anisole (4) readily reacted with CCl4 and PrOH in
the presence of iron catalysts to give a mixture of
propyl 2-methoxybenzoate (5c) and propyl 4-meth-
oxybenzoate (6c). The most efficient catalysts were
FeBr3 and FeCl3·6H2O (Table 2). The overall yield of
5c and 6c was 91% (1 : 5) in the presence of
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BAYGUZINA et al.
Table 1. Reaction of phenol with alcohols and carbon tetrachloride in the presence of iron catalystsa
Yield, %
Molar ratio
[Fe] : [PhOH] : [CCl4] : [ROH]
Catalyst
Fe2(CO)9
ROH
2a–2d
34
13
10
19
6
3a–3d
66
5
PrOH
5 : 100 : 500 : 500
1 : 100 : 500 : 500
10 : 100 : 1000 : 1000
''
FeCl3·6H2O
FeCl2·4H2O
FeCl3
''
''
17
59
7
''
''
1 : 100 : 500 : 500
10 : 100 : 1000 : 1000
1 : 100 : 500 : 500
''
FeBr3
''
14
20
22
35
28
9
26
22
20
65
43
26
15
60
32
50
29
66
41b
59c
20
45
62
FeCl2
''
FeBr2
''
Fe(асас)3
''
10 : 100 : 1000 : 1000
10 : 100 : 500 : 500
1 : 100 : 1000 : 1000
1 : 100 : 500 : 500
10 : 100 : 1000 : 1000
1 : 100 : 1000 : 1000
10 : 100:300:300
1 : 100 : 500 : 500
5 : 100 : 500 : 500
''
''
''
''
7
Fe2(CO)9
''
40
17
30
24
34
25b
31c
18
28
38
''
''
''
''
''
''
''
MeOH
EtOH
BuOH
5 : 100 : 500 : 500
''
''
a
130°C, 6 h. b 130°C, 4 h. c 130°C, 8 h.
FeCl3·6H2O and 100% (1 : 3.3) in the presence of
FeBr3 (Fe–4–CCl4–PrOH molar ratio 1 : 100 : 500 :
500; 30°C, 6 h). Under analogous conditions, the
reactions of 4 with methanol, ethanol, and butan-1-ol
gave methyl (5a, 6a), ethyl (5b, 6b), and butyl
methoxybenzoates (5d, 6d) (Scheme 2, Table 2).
were optimized using the reaction of o-cresol (10) with
propanol and carbon tetrachloride catalyzed by FeBr3,
Fe2(CO)9, FeCl2, FeCl3, and Fe(acac)3. There was no
reaction in the absence of a catalyst. In the reaction
catalyzed by Fe2(CO)9 at a Fe2(CO)9–10–CCl4–PrOH
molar ratio of 10 : 100 : 300 : 300 (150°C, 6 h), propyl
2-hydroxy-3-methylbenzoate 13c was formed in s 12%
yield (Scheme 4), whereas the main part of the
substrate was converted to tars.
Likewise, by reaction of phenetole (7) with CCl4
and PrOH in the presence of FeBr3 we obtained propyl
2- and 4-ethoxybenzoates 8c and 9c in 24 and 76%
yields, respectively (Scheme 3).
Under analogous conditions, from p- and m-cresols
11 and 12 we obtained propyl 2-hydroxy-5-methyl-
benzoate (14c) and propyl 2-hydroxy-4-methyl-
benzoate (15c) in 20 and 10% yields, respectively. The
Unlike phenol (1), cresols 10–12 reacted with
carbon tetrachloride and alcohols in a non-selective
manner, regardless of the iron catalyst. The conditions
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SYNTHESIS OF HYDROXYBENZOIC ACIDS AND THEIR ESTERS
211
Table 2. Reaction of anisole with alcohols and carbon tetrachloride in the presence of iron catalystsa
Yield, %
Catalyst
ROH
Molar ratio Fe : PhOMe : CCl4 : ROH
5a–5d
37
27
15
4
6a–6d
62
46
76
19
54
46
42
73
76
48
47
77
51
65
77
37
54
36
36b
79c
46
17
77
82
43
36
34
56
36
17
FeCl3·6H2O
PrOH
10 : 100 : 1000 : 1000
''
1 : 100 : 1000 : 1000
''
1 : 100 : 500 : 500
MeOH
''
EtOH
''
5
BuOH
''
9
Fe2 (CO)9
PrOH
10 : 100 : 1000 : 1000
37
27
24
13
14
15
40
35
23
22
22
14
6b
''
1 : 100 : 1000 : 1000
''
10 : 100 : 500 : 500
''
1 : 100 : 500 : 500
FeCl3(anhydrous)
FeBr3
''
10 : 100 : 1000 : 1000
''
''
''
10 : 100 : 500 : 500
''
1 : 100 : 1000 : 1000
''
1 : 100 : 500 : 500
''
1 : 100:400:400
''
1 : 100:200:200
''
1 : 100 : 100 : 100
''
1 : 100 : 500 : 500
''
''
''
''
''
''
''
''
''
''
''
''
21c
15
2
MeOH
EtOH
PrOH
23
12
23
20
24
35
14
8
BuOH
FeCl2
PrOH
FeBr2
''
''
''
''
''
Fe(асас)3
FeCl2·4H2O
Fe(OAc)2
Fe(OAc)2·4 H2O
a
130°C, 6 h. b 130°C, 4 h. c 130°C, 8 h.
substrate conversion was complete, and a large amount
of tarry products was formed. In all cases, the
formation of hydrogen chloride and ethers derived
from the corresponding alcohols was observed.
Taking into account the composition of the reaction
products, the following mechanism of formation of
ester group may be proposed. In the first stage, phenol
1 is alkylated with carbon tetrachloride, and the
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BAYGUZINA et al.
Scheme 5.
[Fe2(CO)9Cl]_[CCl3]+
Fe2(CO)9 + CCl4
OH
OH
OH
[Fe2(CO)9Cl]_[CCl3]+
3ROH
CCl3
CO2R
_3HCl
_3ROR
_HCl
_Fe2(CO)9
16
2, 3
1
ROH + HCl
RCl + H2O
resulting isomeric trichloromethylphenols 16 undergo
alcoholysis to give esters 2 and 3 (Scheme 5).
reactions were carried out in 10-mL glass ampules
which were placed in a 17-mL stainless-steel high-
pressure micro reactor with controlled heating. An
ampule was charged under argon with 1–10 mmol of
the catalyst [FeCl3, FeBr3, FeCl2, FeBr2, FeCl3·6H2O,
FeCl3·4H2O, Fe(acac), or Fe2(CO)9], 100 mmol of
phenol, anisole, phenetole, or o-, m-, or p-cresol, 100–
1000 mmol of CCl4, and 100–1000 mmol of methanol,
ethanol, propan-1-ol, or butan-1-ol. The ampule was
sealed and placed into the reactor which was
hermetically closed and heated for 4–8 h at 130°C with
continuous stirring. The reactor was cooled to 20°C,
the ampule was opened, and the mixture was neutralized
with Na2CO3, treated with boiling petroleum ether for
10–15 min, and filtered through a filter paper. The
solvent was distilled off, and the residue was distilled
under reduced pressure or subjected to chromato-
graphy in a column (h = 21, d = 1.2 cm) charged with
silica gel using petroleum ether as eluent. Analytical
samples were obtained by recrystallization from
ethanol.
In summary, we have developed a new method for
the introduction of ester group into phenol, anisole,
phenetole, and o-, p-, and m-cresol molecule via iron-
catalyzed reaction with carbon tetrachloride and
alcohols. The product structure was confirmed by
NMR and mass spectra, as well as by comparing with
authentic samples and reference data.
EXPERIMENTAL
1
The H and 13C NMR spectra were recorded on a
Bruker Avance-400 spectrometer at 400.13 and
100.62 MHz, respectively, using CDCl3 as solvent and
tetramethylsilane as internal standard. The mass spectra
were obtained on a Shimadzu GCMS-QP 2010Plus
instrument (SPB-5 capillary column, 30 m × 0.25 mm,
carrier gas helium; oven temperature programming
from 40 to 300°C at a rate of 8 deg/min; injector
temperature 280°C, ion source temperature 200°C;
electron impact, 70 eV). Gas chromatographic analysis
was performed with Shimadzu GC-9A and GC-2014
instruments (2-m × 3-mm column packed with 5%
SE-30 on Chromaton N-AW-HMDS; oven temperature
programming from 50 to 270°C at a rate of 8 deg/min;
carrier gas helium, flow rate 47 mL/min). Gaseous
products were analyzed using a Shimadzu GCMS-
QP2010Ultra instrument (Supel-Q PLOT caipllary
column, 30 m × 0.53 mm; oven temperature prog-
ramming from 37 to 250°C at a rate of 10 deg/min;
carrier gas helium, flow rate 3 mL/min; ion source
temperature 200°C, electron impact, 70 eV).
Methyl 2-hydroxybenzoate (2a). Yield 18%, bp
100‒102°C (12 mm); published data [13]: bp 40–50°C
1
(3 mm). H NMR spectrum (CDCl3), δ, ppm: 3.95 s
(3H, CH3), 6.95–7.20 m (1H, 5-H), 6.90–7.20 m (1H,
3-H), 7.40–7.60 m (1H, 4-H), 7.90–8.0 m (1H, 6-H),
10.98 br.s (1H, OH). 13C NMR spectrum, δC, ppm:
52.52 (OCH3), 112.46 (C1), 117.58 (C3), 119.58 (C5),
130.09 (C6), 135.98 (C4), 161.22 (C2), 170.86 (C=O).
Mass spectrum, m/z (Irel, %): 152 (40) [M]+, 120 (100),
92 (60), 65 (20), 53 (5).
Ethyl 2-hydroxybenzoate (2b). Yield 28%, bp 106–
108°C (12 mm); published data [14]: bp 125–130°C
1
(18 mm). H NMR spectrum (CDCl3), δ, ppm: 1.57–
Commercial solvents and reagents of analytical
grade were used.
1.63 m (3H, CH3), 4.37–4.45 m (2H, OCH2), 6.95–
6.97 m (1H, 5-H), 6.95–6.97 m (1H, 3-H), 7.46–7.50
m (1H, 4-H), 7.89 d (1H, 6-H, J = 8 Hz), 10.96 br. s
(1H, OH). 13C NMR spectrum, δC, ppm: 14.21
(CH2CH3), 61.56 (OCH2), 115.60 (C1), 117.55 (C3),
Alkyl esters of hydroxy-, methoxy-, and ethoxy-
benzoic and cresotic acids 2a–2d, 3a–3d, 5a–5d, 6a–
6d, 8c, 9c, 13c, 14c, and 15c (general procedure). The
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SYNTHESIS OF HYDROXYBENZOIC ACIDS AND THEIR ESTERS
213
119.27 (C5), 129.90 (C6), 135.70 (C4), 161.52 (C2),
171.02 (C=O). Mass spectrum, m/z (Irel, %): 166 (30)
[M]+, 138 (15), 120 (100), 92 (30), 65 (15), 41 (10).
spectrum (CDCl3), δ, ppm: 0.65–1.2 m (3H, CH3), 1.75–
1.90 m (2H, CH2CH3), 4.25–4.40 m (2H, OCH2), 5.31
br.s (1H, OH), 6.88 d (2H, 3-H, 5-H, J = 7.8 Hz), 7.97
d (2H, 2-H, 6-H, J = 8.0 Hz). 13C NMR spectrum, δC,
ppm: 10.52 (CH3), 22.11 (CH2CH3), 67.03 (OCH2),
115.38 (C3, C5), 120.62 (C1), 131.93 (C2, C6), 160.45
(C4), 167.31 (C=O). Mass spectrum, m/z (Irel, %): 180
(5) [M]+, 138 (45), 121 (100), 93 (15), 65 (29), 41 (5).
Propyl 2-hydroxybenzoate (2c). Yield 34%, bp
120–122°C (12 mm); published data [15]: bp 238–
1
240°C. H NMR spectrum (CDCl3), δ, ppm: 0.65–1.2
m (3H, CH3), 1.75–1.90 m (2H, CH2CH3), 4.25–4.40
m (2H, OCH2), 6.70–7.20 m (1H, 5-H), 6.93 d (1H,
3-H, J = 6.9 Hz), 7.20–7.55 m (1H, 4-H), 7.83 d (1H,
6-H, J = 8.0 Hz), 10.94 br.s (1H, OH). 13C NMR
spectrum, δC, ppm: 10.45 (CH2CH3), 21.98 (CH2CH3),
66.65 (OCH2), 115.30 (C1), 117.75 (C3), 119.26 (C5),
129.93 (C6), 135.68 (C4), 161.49 (C2), 170.37 (C=O).
Mass spectrum, m/z (Irel, %): 180 (15) [M]+, 138 (15),
120 (100), 92 (30), 65 (15), 41 (10).
Butyl 4-hydroxybenzoate (3d). Yield 62%, mp
1
65–67°C; published data [17]: mp 64–66°C. H NMR
spectrum (CDCl3), δ, ppm: 0.70–1.1 m (3H, CH3), 1.20–
1.70 m (2H, CH2CH3), 1.65–1.80 m (2H, OCH2CH2),
4.20–4.45 m (2H, OCH2), 5.31 br.s (1H, OH), 6.99 d
(2H, 3-H, 5-H, J = 8.4 Hz), 7.87 d (2H, 2-H, 6-H, J =
8.0 Hz). 13C NMR spectrum, δC, ppm: 18.87 (CH3),
19.33 (CH2CH3), 30.81 (OCH2CH2), 65.27 (OCH2),
115.37 (C3, C5), 120.35 (C1), 131.83 (C2, C6), 160.71
(C4), 166.99 (C=O). Mass spectrum, m/z (Irel, %): 194
(10) [M]+, 138 (80), 121 (100), 93 (15), 65 (20), 41
(10).
Butyl 2-hydroxybenzoate (2d). Yield 38%, bp 145–
147°C (16 mm). Published data [15]: bp 259–260°C.
1H NMR spectrum (CDCl3), δC, ppm: 0.70–1.1 m (3H,
CH3), 1.20–1.70 m (2H, CH2CH3), 1.65–1.80 m (2H,
OCH2CH2), 4.20–4.45 m (2H, OCH2), 6.90 t (1H, 5-H,
J = 7.6 Hz), 7.24 br.s (1H, 3-H), 7.47 t (1H, 4-H, J =
7.6 Hz), 7.95 br.s (1H, 6-H), 10.90 br.s (1H, OH). 13C
NMR spectrum, δC, ppm: 18.87 (CH2CH3), 19.29
(CH2CH3), 30.59 (OCH2CH2), 64.70 (OCH2), 115,25
(C1), 117.54 (C3), 119.17 (C5), 129.89 (C6), 135.62
(C4), 161.57 (C2), 170.30 (C=O). Mass spectrum, m/z
(Irel, %): 194 (20) [M]+, 138 (25), 120 (100), 92 (20),
65 (15), 41 (10).
Methyl 2-methoxybenzoate (5a). Yield 15%, bp
118–120°C (12 mm); published data [18]: bp 76–78°C
1
(1 mm). H NMR spectrum (CDCl3), δ, ppm: 3.81 s
(3H, OCH3), 3.99 s (3H, OCH3), 7.0–7.24 m (1H,
3-H), 7.0–7.24 m (1H, 4-H), 7.45–7.60 m (1H, 4-H),
7.92 d (1H, 6-H, J = 8.0 Hz). 13C NMR spectrum, δC,
ppm: 53.44 (OCH3), 55.95 (2-OCH3), 112.05 (C3),
120.17 (C5), 120.51 (C1), 129.63 (C6), 133.62 (C4),
159.23 (C2), 166.15 (C=O). Mass spectrum, m/z (Irel,
%): 166 (25) [M]+, 135 (100), 120 (5), 92 (15), 77 (60),
51 (20), 45 (2).
Methyl 4-hydroxybenzoate (3a). Yield 20%, mp
129–131°C; published data [15]: mp 131°C, bp 270–
1
280°C. H NMR spectrum (CDCl3), δ, ppm: 3.99 s
(3H, CH3), 5.31 br.s (1H, OH), 6.90–7.2 m (2H, 3-H,
5-H), 7.91–7.99 m (2H, 2-H, 6-H). 13C NMR spectrum,
δC, ppm: 52.42 (OCH3), 115.49 (C3, C5), 121.83 (C1),
132.82 (C2, C6), 160.67 (C4), 168.32 (C=O). Mass
spectrum, m/z (Irel, %): 152 (30) [M]+, 121 (100), 93
(25), 65 (20), 53 (2).
Ethyl 2-methoxybenzoate (5b). Yield 32%, bp 135–
136°C (12); published data [15]: bp 246–248°C
1
(732 mm). H NMR spectrum (CDCl3), δ, ppm: 1.38 t
(3H, CH2CH3, J = 8.0 Hz), 3.93 s (3H, OCH3) 4.30–
4.45 m (2H, OCH2), 6.95–7.5 m (1H, 5-H), 6.95–7.5 m
(1H, 3-H), 7.45–7.55 m (1H, 4-H), 7.81 d (1H, 6-H,
J = 6.4 Hz). 13C NMR spectrum, δC, ppm: 14.32
(CH2CH3), 55.99 (OCH3), 60.80 (OCH2), 112.06 (C3),
120.50 (C1), 120.55 (C5), 131.48 (C6), 133.32 (C4),
159.13 (C2), 166.38 (C=O). Mass spectrum, m/z (Irel,
%): 180 (10) [M]+, 165 (2), 135 (100), 133 (45), 105
(20), 77 (45), 64 (10), 51 (10).
Ethyl 4-hydroxybenzoate (3b). Yield 45%, mp
1
115–116°C; published data [15]: mp 116°C. H NMR
spectrum (CDCl3), δ, ppm: 1.39–1.47 m (3H, CH3),
4.37–4.46 m (2H, CH2CH3), 5.31 br.s (1H, OH), 6.87–
6.89 m (2H, 3-H, 5-H), 7.97 d (2H, 2-H, 6-H, J =
7.2 Hz). 13C NMR spectrum, δC, ppm: 14.32 (CH3),
61.15 (OCH2), 115.31 (C3, C5), 122.43 (C1), 131.97
(C2, C6), 160.30 (C4), 167.31 (C=O). Mass spectrum,
m/z (Irel, %): 166 (15) [M]+, 138 (45), 121 (100), 93
(15), 65 (25), 41 (5).
Propyl 2-methoxybenzoate (5c). Yield 40%, bp
140–146°C (10 mm); published data [19]: bp 114.8–
1
115.5°C (1.5 mm). H NMR spectrum (CDCl3), δ,
ppm: 1.03 t (3H, CH2CH3, J = 6.0 Hz), 1.72–1.84 m
(2H, CH2CH3), 3.91 s (3H, OCH3), 4.23–4.28 m (2H,
OCH2), 6.95–7.02 m (1H, 5-H), 6.99–7.02 m (1H,
Propyl 4-hydroxybenzoate (3c). Yield 66%, mp
1
95–97°C; published data [16]: mp 93–95°C. H NMR
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BAYGUZINA et al.
3-H), 7.42–7.50 m (1H, 4-H), 7.77–7.85 m (1H, 6-H).
13C NMR spectrum, δC, ppm: 10.53 (CH2CH3), 22.16
(CH2CH3), 55.94 (OCH3), 66.40 (OCH2), 112.02 (C3),
117.54 (C1), 120.83 (C5), 133,31 (C6), 135.57 (C4),
159.11 (C2), 166.34 (COO). Mass spectrum, m/z (Irel,
%): 194 (15) [M]+, 152 (5), 135 (100), 123 (30), 105
(25), 77 (40), 64 (7), 51 (10).
163.50 (C4), 166.46 (C=O). Mass spectrum, m/z (Irel,
%): 194 (15) [M]+, 152 (50), 135 (100), 121 (5), 107
(10), 77 (20), 64 (5), 51 (10).
Butyl-4-methoxybenzoate (6d). Yield 82%, bp
124–126°C (2 mm); published data [15]: bp 183°C
1
(40 mm). H NMR spectrum (CDCl3), δ, ppm: 0.98 t
(3H, CH2CH3, J = 7.2 Hz), 1.45–1.80 m (2H,
CH2CH3), 1.45–1.80 m (2H, OCH2CH2), 3.85 s (3H,
OCH3), 4.25–4.35 m (2H, OCH2), 6.92 d (2H, 3-H, 5-
Butyl 2-methoxybenzoate (5d). Yield 12%, bp 120–
122°C (2 mm); published data [19]: bp 112°C
1
13
(1.2 mm). H NMR spectrum (CDCl3), δ, ppm: 0.90–
H, J = 8.4 Hz), 8.01 d (2H, 2-H, 6-H, J = 8.8 Hz). C
1.0 m (3H, CH2CH3), 1.45–1.80 m (2H, CH2CH3),
1.45–1.80 m (2H, OCH2CH2), 3.90 s (3H, OCH3), 4.25–
4.35 m (2H, OCH2), 6.8–7.0 m (1H, 5-H), 6.8–7.0 m
(1H, 3-H), 7.40–7.50 m (1H, 4-H), 7.79 d (1H, 6-H,
J = 8.8 Hz). 13C NMR spectrum, δC, ppm: 13.84
(CH2CH3), 18.90 (CH2CH3), 30.74 (OCH2CH2), 55.90
(OCH3), 62.63 (OCH2), 112.03 (C3), 120.07 (C5),
120.62 (C1), 132.14 (C6), 133.35 (C4), 159.14 (C2),
166.39 (C=O). Mass spectrum, m/z (Irel, %): 208 (15)
[M]+, 152 (10), 105 (25), 92 (20), 77 (40), 51 (5), 41 (10).
NMR spectrum, δC, ppm: 13.75 (CH2CH3), 19.28
(CH2CH3), 30.82 (OCH2CH2), 55.37 (OCH3), 64.54
(OCH2), 113.55 (C3, C5), 122.92 (C1), 131.52 (C2, C6),
163.27 (C4), 166.51 (C=O). Mass spectrum, m/z (Irel,
%): 208 (15) [M]+, 152 (90), 135 (100), 107 (15), 92
(20), 77 (25), 64 (10), 41 (10).
Propyl 2-ethoxybenzoate (8c). Yield 40%, bp 112–
1
114°C (1 mm). H NMR spectrum (CDCl3), δ, ppm:
1.05 t (3H, CH3, J = 6.0 Hz), 1.41 t (OCH2CH3, J =
6.2 Hz), 1.73–1.87 m (2H, CH2CH2CH3), 4.05 q (OCH2·
CH3, J = 6.4 Hz), 4.20–4.29 m (2H, OCH2CH2CH3),
6.95–7.04 m (1H, 5-H), 6.97–7.03 m (1H, 3-H), 7.40–
7.49 m (1H, 4-H), 7.75–7.85 m (1H, 6-H). 13C NMR
spectrum, δC, ppm: 10.56 (CH2CH2CH3), 15.65 (OCH2·
CH3), 22.36 (CH2CH2CH3), 65.42 (OCH2CH3), 66.54
(OCH2CH2CH3), 112.18 (C3), 118.07 (C1), 120.87 (C5),
133.58 (C6), 135.69 (C4), 159.53 (C2), 166.59 (C=O).
Mass spectrum, m/z (Irel, %): 208 (15) [M]+, 194 (10), 152
(5), 135 (100), 123 (34), 105 (30), 77 (44), 64 (5), 51 (10).
Methyl 4-methoxybenzoate (6a). Yield 46%, bp
123–124°C (10 mm); published data [15]: bp 256°C.
1H NMR spectrum (CDCl3), δ, ppm: 3.89 s (3H,
OCH3), 3.94 s (3H, OCH3), 6.92–7.0 m (2H, 3-H, 5-H),
8.05 d (2H, 2-H, 6-H, J = 8.8 Hz). 13C NMR spectrum,
δC, ppm: 51.91 (OCH3), 55.41 (4-OCH3), 113.66 (C3,
C5), 121.51 (C1), 131.65 (C2, C6), 163.63 (C4), 167.06
(C=O). Mass spectrum, m/z (Irel, %): 166 (30) [M]+,
135 (100), 107 (15), 92 (15), 77 (25), 64 (15).
Ethyl 4-methoxybenzoate (6b). Yield 68%, bp 133–
134°C (10 mm); published data [15]: bp 263°C. H
Propyl 4-ethoxybenzoate (9c). Yield 78%, bp 125–
1
127°C (2 mm); published data [20]: bp 155–157°C
1
NMR spectrum (CDCl3), δ, ppm: 1.38 t (3H, CH2CH3,
J = 8.0 Hz), 3.88 s (3H, OCH3), 4.30–4.35 m (2H,
OCH2), 6.9 d (2H, 3-H, 5-H, J = 8.8 Hz), 8.03 d (2H,
2-H, 6-H, J = 8.8 Hz). 13C NMR spectrum, δC, ppm:
14.39 (CH2CH3), 55.24 (OCH3), 60.64 (OCH2), 113.55
(C3, C5), 122.98 (C1), 131.54 (C2, C6), 163.26 (C4),
166.42 (C=O). Mass spectrum, m/z (Irel, %): 180 (30)
[M]+, 165 (2), 152 (15), 135 (100), 107 (10), 92 (15), 77
(20), 64 (5).
(14 mm). H NMR spectrum (CDCl3), δ, ppm: 1.08 t
(3H, CH3, J = 7.4 Hz), 1.36 t (OCH2CH3, J = 6.2 Hz),
1.72–1.87 m (2H, CH2CH2CH3), 4.01 q (OCH2CH3,
J = 6.4 Hz), 4.36 t (2H, OCH2CH2CH3, J = 6.8 Hz),
6.97 d (2H, 3-H, 5-H, J = 8.0 Hz), 8.08 d (2H, 2-H,
6-H, J = 8.0 Hz). 13C NMR spectrum, δC, ppm: 10.55
(CH2CH2CH3), 13.98 (OCH2CH3), 22.24 (CH2CH2CH3),
62.58 (OCH2CH3), 66.63 (OCH2CH2CH3), 113.78 (C3,
C5), 122.86 (C1), 131.58 (C2, C6), 164.11 (C4), 166.89
(C=O). Mass spectrum, m/z (Irel, %): 208 (15) [M]+,
194 (10), 152 (50), 135 (100), 121 (8), 107 (10), 77
(21), 64 (8), 51 (12).
Propyl 4-methoxybenzoate (6c). Yield 78%, bp
112–115°C (2 mm); published data [15]: bp 176°C
1
(45 mm). H NMR spectrum (CDCl3), δ, ppm: 1.05 t
(3H, CH2CH3, J = 7.6 Hz), 1.7–1.85 m (2H, CH2CH3),
3.88 s (3H, OCH3), 4.27 t (2H, OCH2, J = 6.8 Hz),
6.93 d (2H, 3-H, 5-H, J = 8.0 Hz), 8.02 d (2H, 2-H,
6-H, J = 8.0 Hz). 13C NMR spectrum, δC, ppm: 10.54
(CH2CH3), 22.17 (CH2CH3), 55.41 (OCH3), 66.24
(OCH2), 113.55 (C3, C5), 122.9 (C1), 131.54 (C2, C6),
Propyl 2-hydroxy-3-methylbenzoate (13c). Yield
10%, bp 122–125°C (6 mm). 1H NMR spectrum
(CDCl3), δ, ppm: 1.06 t (3H, CH2CH3, J = 7.2 Hz),
1.77–1.86 m (2H, CH2CH3), 2.29 s (3H, 3-CH3), 4.32 t
(2H, OCH2, J = 6.6 Hz), 6.90 t (1H, 5-H, J = 8 Hz),
7.33 d (1H, 6-H, J = 7.24 Hz), 7.73 d (1H, 4-H, J =
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 2 2018

SYNTHESIS OF HYDROXYBENZOIC ACIDS AND THEIR ESTERS
215
7.24 Hz). 13C NMR spectrum, δC, ppm: 10.52
(CH2CH3), 15.66 (3-CH3), 22.03 (CH2CH2CH3), 66.89
(OCH2), 114.67 (C3), 118.61 (C5), 126.61 (C1), 127.43
(C4), 136.52 (C6), 165.47 (C2), 172.2 (C=O). Mass
spectrum, m/z (Irel, %): 194 (10) [M]+, 152 (45), 135
(100), 107 (25), 77 (40), 51 (5), 41 (10).
and Seitenova, G.Zh., Pet. Chem., 2009, vol. 49, no. 4,
p. 265. doi 10.1134/S096554410904001X
4. Suerbaev, Kh.A., Akhmetova, G.B., and Shalmagam-
betov, K.M., Russ. J. Gen. Chem., 2005, vol. 75, no. 9,
p. 1498. doi 10.1007/s11176-005-0454-0
5. Komiyama, M. and Hirai, H., J. Am. Chem. Soc., 1984,
vol. 106, p. 174. doi 10.1021/ja00313a035
Propyl 4-hydroxy-5-methylbenzoate (14c). Yield
98%, bp 125–127°C (6 mm). 1H NMR spectrum
(CDCl3), δ, ppm: 1.0 t (3H, CH2CH3, J = 8.0 Hz), 1.48–
1.7 m (2H, CH2CH3), 2.32 s (3H, 5-CH3), 4.33 t (2H,
OCH2, J = 6.4 Hz), 6.9 d (1H, 5-H, J = 8.4 Hz), 7.20–
7.30 m (1H, 6-H), 7.66 s (1H, 2-H), 10.67 s (1H, OH).
13C NMR spectrum, δC, ppm: 10.47 (CH2CH3), 20.40
(5-CH3), 22.0 (CH2CH3), 66.82 (OCH2), 112.19 (C3),
117.33 (C5), 128.24 (C1), 129.51 (C2), 136.55 (C6),
159.57 (C4), 170.28 (C=O). Mass spectrum, m/z (Irel,
%): 194 (30) [M]+, 152 (10), 134 (100), 121 (5), 106
(20), 77 (20), 63 (5), 50 (2).
6. Komiyama, M. and Hirai, H., Makromol. Chem. Rapid
Commun., 1981, vol. 2, p. 661. doi 10.1002/
marc.1981.030021103
7. Komiyama, M., Sugiura, I., and Hirai, H., J. Mol.
Catal., 1986, vol. 36, p. 271. doi 10.1016/0304-5102
(86)85083-0
8. Takahashi, K., Chem. Rev., 1998, vol. 98, p. 2013. doi
10.1021/cr9700235
9. Khusnutdinov, R.I., Shchadneva, N.A., Baiguzina, A.R.,
Mukminov, R.R., Mayakova, Yu.Yu., Smirnov, A.A.,
and Dzhemilev, U.M., Pet. Chem., 2008, vol. 48, no. 6,
p. 471. doi 10.1134/S0965544108060121
10. Khusnutdinov, R.I., Bayguzina, A.R., Denisov, K.Y.,
and Dzhemilev, U.M., Mendeleev Commun., 2015,
vol. 25, no. 3, p. 219. doi 10.1016/j.mencom.2015.05.021
11. Baiguzina, A.R., Erokhina, I.S., and Khusnutdinov, R.I.,
Russ. J. Gen. Chem., 2017, vol. 87, no. 3, p. 389. doi
10.1134/S1070363217030057
12. Khusnutdinov, R.I., Bayguzina, A.R., and Dzhemilev, U.M.,
Russ. J. Org. Chem., 2017, vol. 53, no. 8, p. 1113. doi
10.1134/S1070428017080012
Propyl 3-hydroxy-4-methylbenzoate (15c). Yield
10%, bp 124–126°C (6 mm). 1H NMR spectrum
(CDCl3), δ, ppm: 1.06 t (3H, CH2CH3, J = 6.4 Hz),
1.78–1.88 m (2H, CH2CH3), 2.36 s (3H, 4-CH3), 4.32 t
(2H, OCH2, J = 4.9 Hz), 6.73 d (1H, 6-H), 6.83 s (1H,
2-H), 7.75 d (1H, 5-H), 10.85 s (1H, OH). 13C NMR
spectrum, δC, ppm: 11.01 (CH2CH3), 21.98 (CH2CH3),
22.01 (4-CH3), 66.74 (OCH2), 110.10 (C4), 117.70
(C2), 120.43 (C6), 129.41 (C5), 146.94 (C1), 161.56
(C3), 170.31 (C=O). Mass spectrum, m/z (Irel, %): 194
(22) [M]+, 152 (11), 134 (100), 121 (6), 106 (25), 77
(25), 51 (5).
13. Selva, M. and Tundo, P., J. Org. Chem., 2006, vol. 71,
no. 4, p. 1464. doi 10.1021/jo0520792
14. Downie, I.M., Tetrahedron, 1982, vol. 38, no. 10,
p. 1457. doi 10.1016/0040-4020(82)80230-5
15. Dictionary of Organic Compounds, Heilbron, J. and
Bunbury, H.M., Eds., London: Eyre and Spottswoode,
1953, vols. 1–3.
16. Hazarika, K., Parajuli, R., and Phukan, P., Indian J.
Chem. Technol., 2007, vol. 14, p. 104.
ACKNOWLEDGMENTS
The spectral studies were performed at the Agidel
Joint Center (Institute of Petrochemistry and Catalysis,
Russian Academy of Sciences.
17. Owen, C., J. Pharm. Pharmacol., 2002, vol. 55, no. 1,
p. 85. doi 10.1211/002235702568
18. Barry, J., Synthesis, 1985, vol. 1, p. 40. doi 10.1055/s-
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 2 2018