a-Hydroxycarboxylic Acids Synthesis
33
magnesium anode. Before electrolysis, the O in the system was removed by
2
passing N gas through this solution. The mechanically stirred homogeneous
2
solution was electrolyzed at about 258C at constant current density of 10 mA/
2
cm under a constant pressure (1 atm.) of carbon dioxide until 2 F/mol of elec-
tricity was passed. After electrolysis, the power supply was shut off, and the
solution was transferred to a round-bottom flask. The DMF solvent was
stripped in a rotary evaporator until a viscous residue was obtained. The
residue was stirred well in 50 mL of toluene for about 5 h for removal of
uncorrected starting material. The mixture was filtered, and the solid was
stirred well in 50 mL of 5% aqueous hydrochloric acid for 5 h. The product
was extracted with diethylether (90 mL) and dried over MgSO . Evaporation
4
of solvent afforded 1.41 g of 2-hydroxy-2-phenylpropanoic acid (2a) in 85%
17]
[
yield; mp 113–1148C [lit.
mp 115–1168C]. IR (neat): n ¼ 3485 (OH)
2
1
21 1
cm , 1732 (C 55 O) cm . H NMR (CDCl ): d ¼ 11.34 (bs, 1H, –COOH),
3
9
calcd for C H O (166.18): C, 65.05; H, 6.07. Found: C, 65.14; H, 6.02.
.32 (bs, 1H, OH), 7.11–7.32 (m, 5H, Ar-H), 1.92 (s, 3H, CH ). Anal.
3
9
10 3
2
-Hydroxy-2-(4-hydroxyphenyl)propanoic acid (2b): Yield 83%; mp
21
[
18]
2
18–2208C [lit.
mp 220–2238C]. IR (neat): n ¼ 3481 (OH) cm , 1726
2
1 1
(
C 55 O) cm . H NMR (CDCl ): d ¼ 11.45 (bs, 1H, –COOH), 9.12 (bs,
3
OH), 4.53 (s, 1H, Ar-OH), 7.08–7.23 (m, 4H, Ar-H), 1.91 (s, 3H, CH ).
3
Anal. calcd. for C H O (182.17): C, 59.34; H, 5.53. Found: C, 59.09;
9
10 4
H, 5.61.
2
-Hydroxy-2-(4-methoxyphenyl)propanoic acid (2c): Yield 82%; mp
[
19]
21
mp 146–1478C]. IR (neat): n ¼ 3472 (OH) cm , 1728
1
45–1478C [lit.
2
1 1
(
C 55 O) cm . H NMR (CDCl ): d ¼ 11.48 (bs, 1H, –COOH), 9.25 (bs,
3
1
CH ). Anal. calcd. for C H O (196.20): C, 61.22; H, 6.16. Found: C,
H, OH), 7.01–7.19 (m, 4H, Ar-H), 3.81 (s, 1H, –OCH ), 1.99 (s, 3H,
3
3
10 12 4
6
1.08; H, 6.19.
2
-(4-cyanophenyl)-2-Hydroxypropanoic acid (2d): Yield 85%, mp 196–
[
18]
21
mp 199–2018C]. IR (neat): n ¼ 2234 (CN) cm , 3462 (OH)
1
988C [lit.
2
1
21 1
cm , 1733 (C 55 O) cm . H NMR (CDCl ): d ¼ 11.39 (bs, 1H, –COOH),
3
9
calcd. for C H NO (191.18): C, 62.82; H, 4.74; N, 7.33. Found: C, 62.90;
.27 (bs, 1H, OH), 7.15–7.29 (m, 4H, Ar-H), 1.81 (s, 3H, CH ). Anal.
3
1
0
9
3
H, 4.71; N, 7.18.
-Hydroxy-2-(4-nitrophenyl)propanoic acid (2e): Yield 86%; mp 219–
2
2
1
21
1
2
208C. IR (neat): n ¼ 3468 (OH) cm , 1725 (C 55 O) cm . H NMR
(
CDCl ): d ¼ 11.51 (bs, 1H, –COOH), 9.29 (bs, 1H, OH), 7.24–7.41
3
(
m, 4H, Ar-H), 1.77 (s, 3H, CH ). Anal. calcd for C H NO (211.18): C,
3
9
9
5
5
1.19; H, 4.30; N, 6.63. Found: C, 51.28; H, 4.23; N, 6.59.
2
-Hydroxy-2-thiophene-2-yl-propanoic acid (2f): Yield 80%; mp 108–
21
[
20]
1
108C, [lit.
mp 111–1138C]. IR (neat): n ¼ 3468 (OH) cm , 1724
2
1 1
(
C 55 O) cm . H NMR (CDCl ): d ¼ 11.42 (bs, 1H, –COOH), 9.16 (bs,
3
1
C H O S (172.2): C, 48.82; H, 4.68; N, 27.87. Found: C, 48.79; H, 4.71;
H, OH), 6.51–6.94 (m, 3H, thio H), 1.61 (s, 3H, CH ). Anal. calcd. for
3
7
8 3
N, 27.81.