H3PW12O40@[bmim][FeCl4]: A Green Catalytic System for Alkoxymethylation of Alcohols
butyl-3-methylimidazolium chloride (17.47 g, 0.1 mol). To
Spectroscopic Data for Selected Products
ensure complete reaction, the reaction mixture was left stirring
over night. A red-brown liquid was obtained which was dried
under high vacuum and stored under N2.
Benzyl acetate (Table 9, entry 1). IR (KBr): ν (cm-1)
3034, 2955, 1741, 1498, 1456, 1381, 1364, 1229, 1082, 1026,
966, 839, 750, 698; 1H NMR (500 MHz, CDCl3): δ (ppm) 2.11
(s, 3H, COCH3), 5.13 (s, 2H, OCH2), 7.34-7.38 (m, 5H, Ar).
2-Acethoxybenzyl acetate (Table 9, entry 4). IR (KBr):
ν (cm-1) 2941, 2291, 2252, 1757, 1445, 1375, 1244, 1041,
Immobilization of H3PW12O40 on [bmim][FeCl4]
H3PW12O40 (1 mol%) was added slowly to 1 ml of highly
pure [bmim][FeCl4] in a round bottomed flask and stirred
roughly. To ensure complete homogenisation, the mixture was
left stirring over night. The catalyst was dried under reduced
pressure and stored under N2.
1
918, 750, 698; H NMR (500 MHz, CDCl3): δ (ppm) 2.05 (s,
3H, CH2OCOCH3), 2.31 (s, 3H, OCOCH3), 5.08 (s, 2H,
CH2OCOCH3), 7.08-7.44 (m, 4H, Ar).
4-Acethoxy-3-methoxybenzyl acetate (Table 9, entry 5).
IR (KBr): ν (cm-1) 2999, 2943, 2850, 2291, 2252, 1738, 1723,
1
1446, 1377, 1246, 1041, 918, 844, 750, 698; H NMR (500
General Procedure for the Preparation of MOM- and
EOM-Ethers at Room Temperature and under
Microwave Irradiation
MHz, CDCl3): δ (ppm) 2.12 (s, 3H, CH2OCOCH3), 2.35 (s,
3H, OCOCH3), 3.78 (s, 3H, OCH3), 5.12 (s, 2H,
CH2OCOCH3), 6.99-7.07 (m, 3H, Ar).
To a solution of alcohol (1 mmol) in FDEA or FDMA (5
mmol) was added H3PW12O40@[bmim][FeCl4] (1 ml) and
stirred at room temperature or exposed to microwave
irradiation (80 W, 75-82 °C) for the appropriate time (Table
4). After completion of the reaction (monitored by TLC,
eluent:n-hexane/ethyl acetate, 4:1), the excess FDMA or
FDEA was removed under reduced pressure. The mixture was
extracted with Et2O (2 × 10 ml). The organic phase was dried
over anhydrous Na2SO4 and rotary evaporation afforded a
residue, which was then passed through a short pad of silica
gel to obtain the highly pure MOM- and EOM-ethers.
4-Chlorobenzyl acetate (Table 9, entry 10). IR (KBr):
ν (cm-1) 3000, 2944, 1800, 1380, 1260, 1120, 1070, 930;
1H NMR (500 MHz, CDCl3): δ (ppm) 2.00 (s, 3H, COCH3),
5.00 (s, 2H, CH2O), 7.20-7.37 (m, 4H, Ar).
2,4-Dichlorobenzyl acetate (Table 9, entry 11). IR
(KBr): ν (cm-1) 3001, 2943, 2848, 2291, 2252, 1743, 1591,
1562, 1446, 1375, 1226, 1105, 1057, 1105, 1056, 918, 842,
1
816, 744; H NMR (500 MHz, CDCl3): δ (ppm) 2.16 (s, 3H,
COCH3), 5.19 (s, 2H, CH2O), 7.27-7.47 (m, 3H, Ar).
4-Nitrobenzyl acetate (Table 9, entry 14). IR (KBr):
ν (cm-1) 2941, 2849, 2291, 2252, 1743, 1533, 1442, 1354,
1
1228, 1097, 1039, 918, 812, 734, 690, 605; H NMR (500
General Procedure for the Interconversion of MOM-
and EOM-Ethers to Acetates and TMS-Ethers under
Thermal Conditions or MW Irradiation
MHz, CDCl3): δ (ppm) 2.16 (s, 3H, COCH3), 5.20 (s, 2H,
CH2O), 7.40-8.40 (m, 4H, Ar).
Benzyloxytrimethylsilane (Table 10, entry 1). IR (KBr):
ν (cm-1) 3063, 3030, 2966, 1711, 1495, 1452, 1227, 1202,
1068, 1028, 916, 812, 758, 694, 605, 547; 1H NMR (500
MHz, CDCl3): δ (ppm) 0.16 (s, 9H, OSi(CH3)3), 4.70 (s, 2H,
CH2OSi(CH3)3), 7.24-7.33 (m, 5H, Ar).
(2-Methoxy-4-((trimethylsilyloxy)methyl)phenoxy)tri-
methylsilane (Table 10, entry 5). IR (KBr): ν (cm-1) 3431,
2956, 2900, 1701, 1637, 1604, 1514, 1463, 1419, 1375, 1280,
1157, 1122, 1037, 904, 850, 754, 688, 634, 557; 1H NMR (500
MHz, CDCl3): δ (ppm) 0.16 (s, 9H, CH2OSi(CH3)3), 0.24 (s,
9H, OSi(CH3)3), 3.83 (s, 3H, OCH3), 4.63 (s, 2H,
CH2Si(CH3)3), 6.77-6.88 (m, 3H, Ar); 13C NMR (125 MHz,
A mixture of EOM- or MOM-ether (1 mmol), acetic
anhydride or hexamethyldisilazane (5 mmol) in H3PW12O40@
[bmim][FeCl4] (1 ml) was stirred under thermal conditions
(70 °C) or microwave irradiation (150 W, 120-130 °C) for the
appropriate time (Tables 9 and 10). After completion of the
reaction, as indicated by TLC, the reaction mixture was
quenched with water and extracted with Et2O (3 × 10 ml). The
organic layer was dried over anhydrous Na2SO4. Evaporation
of the solution and purification with column chromatography
over a short pad of neutral alumina (eluent:n-hexane/ethyl
acetate, 5:1) gave the highly pure acetates or TMS-ethers.
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