Molecules 2019, 24, 177
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0
.3.2. Synthesis and Characterization of 4-((4 -methoxyphenyl)sulfonyl)phenol 4
3
4
In a 100 mL round bottom flask equipped by magnetic stirrer 5 g (20.0 mmol) of
,4’-sulfonyldiphenol, 0.81 mL (20.0 mmol) of methanol, 5.24 g (20.0 mmol) of TPP and 30 mL THF were
added. Obtained reaction mixture was cooled in ice-bath and 8.7 g of DEAD (40% solution in toluene)
was added there dropwise. Then reaction mixture was stirred for 12 h at room temperature. Then excess
of ZnCl solution in ethyl acetate was added to reaction mixture to bind triphenylphosphine oxide
2
(
TPPO) and white crystalline precipitate of ZnCl -TPPO was removed by filtration. Then solvent was
2
removed from filtrate under reduced pressure and obtained oily residue was dissolved in benzene
and washed by 3 20 mL 4 M NaOH. Water layers were collected and combined, and then 1 M
hydrochloric acid solution was added till Ph ≈ 1. Obtained acidic solution was extracted by benzene
× 20 mL, organic fractions were collected and combined. Then solvent was removed under reduced
pressure and target compound was separated by column chromatography (dichloromethane:methanol
×
3
1
00:1 as an eluent).
Synthesis of 4-((4-methoxyphenyl)sulfonyl)phenol was obtained as a white solid at a yield of 48%
−
1
1
(
4
2.55 g). IR (KBr/cm ): 3431 (-OH). H-NMR, CDCl -d1, δ (ppm): 3.83 (s, 3H, CH -O), 6.91–6.95 (m,
3
3
H, Ph-H), 7.42 (br.s, 1H, OH), 7.73–7.83 (m, 4H, Ph-H). 13C-NMR,
δ
(ppm): 163.29, 160.66, 133.28,
1
32.68, 129.60, 129.39, 116.23, 114.58, 55.69. EI MS analysis shows a signal at m/z = 264,1 corresponding
+
to [M] (calc. mass for M (C H O S): 264.05). Elemental analysis for (C H O S). Calculated (%): C,
13
12
4
13 12
4
5
9.08%, H, 4.58%, S, 12.13%. Found (%): C, 59.24%, H, 4.71%, S, 12.18%.
0
3
.3.3. Synthesis and Characterization of (4-cyanatophenyl)(4 -methoxyphenyl)sulfane 7
In a 100 mL round bottom flask equipped by magnetic stirrer 1.0 g (4.3 mmol) of
4
-((4-methoxyphenyl)thio)phenol, 0.9 g (8.6 mmol) of cyanogen bromide and 30 mL of acetone were
◦
added. Obtained reaction mixture was cooled to −30 C and 1.2 mL (8.6 mmol) of triethylamine was
added dropwise and reaction mixture was stirred for 1 h. Then solvent was removed from reaction
mixture under reduced pressure and obtained residue was dissolved in trichloromethane and washed
several times with deionized water. Obtained organic solution was dried over anhydrous Na SO and
2
4
target compound 7 was separated by column chromatography (dichloromethane as an eluent).
Synthesis of (4-cyanatophenyl)(4-methoxyphenyl)sulfane was obtained as a white solid at a yield
−
1
1
of 82% (0.90 g). IR (KBr/cm ): 2360, 2236 (-CN). H-NMR, CDCl -d1, δ (ppm): 3.92 (s, 3H, CH -O),
3
3
7
.00–7.52 (m, 8H, Ar-H). 13C-NMR,
08.67, 55.44. EI MS analysis shows a signal at m/z = 257.1 corresponding to [M] (calc. mass for M
δ
(ppm): 160.36, 150.84, 138.29, 135.94, 129.39, 122.94, 115.87, 115.32,
+
1
(
C H NO S): 257.05). Elemental analysis for (C H NO S). Calculated (%): C, 65.35%, H, 4.31%, S,
14
11
2
14 11
2
1
2.46 %. Found (%): C, 65.53%, H, 4.39%, S, 12.37%.
3
.3.4. Synthesis of 1-cyanato-4-((4-methoxyphenyl)sulfonyl)benzene 8
In a 100 mL round bottom flask equipped by magnetic stirrer 1.0 g (3.8 mmol) of
4
-((4-methoxyphenyl)sulfonyl)phenol, 0.8 g (7.6 mmol) of cyanogen bromide and 30 mL of acetone
◦
were added. Obtained reaction mixture was cooled to
−
30 C and 1.1 mL (7.6 mmol) of triethylamine
was added dropwise and reaction mixture was stirred for 1 h. Then solvent was removed from reaction
mixture under reduced pressure and obtained residue was dissolved in trichloromethane and washed
several times with ice-cold deionized water. Obtained organic solution was dried over anhydrous
Na SO , filtered and then organic solvent was removed under reduced pressure.
2
4
4
. Conclusions
In the current study we synthesized mono-O-methylated bisphenols and used them as precursors
for synthesis of subsequent cyanate esters. It turned out S-bridged cyanate ester is readily available
by proposed synthetic approach and can be obtained with a high purity, which is required for our
further kinetic studies, whereas SO -bridged cyanate ester is hydrolytically unstable and is readily
2