| 98% |
for 20h; Ambient temperature; |
|
| 98% |
With poly(ethylene glycol) 1000 based dicationic acidic ionic liquid In toluene at 80℃; for 1h; Ionic liquid; |
General procedure for acetalization in PEG1000-DAIL/toluene system
General procedure: Aromatic aldehydes (2 mmol) and alcohols (3 mmol) were added into a 10 mL tube reactor preloaded with PEG1000-DAIL(2 mL) and toluene (2 mL). The reacution mixtre was stirred at 80Cfor 1 h. After the reaction, the mixture was cooled to room temperature and the mixture separated into two phases. After decantation of the upper phase, the below phase was reused for the next time after removing water under vacuum at 80C for 1 h. |
| 98% |
With ammonium bisulphate for 6h; Dean-Stark; Reflux; Green chemistry; |
|
| 97% |
With iron(III) chloride for 0.0333333h; Irradiation; |
|
| 97% |
With diphenylamine-terephthalaldehyde resin p-toluenesulfonate with high sulfo group content In toluene for 2h; Dean-Stark; Reflux; chemoselective reaction; |
4. General procedure for the synthesis of ethylene acetals catalyzed by DTRT (H)
General procedure: DTRT (H) (85 mg, 1 mol%) was added to a mixture of undecanal (1a) (1.70 g, 10 mmol) and ethylene glycol (1.05 g, 17 mmol) in toluene (50 mL). The mixture was refluxed for 20 min equipped with Dean-Stark apparatus. The mixture was filtered and the precipitate was washed with toluene. The filtrate was evaporated under reduced pressure. The residue was purified by column chromatography with hexane-acetone (15 : 1) on silica gel to give acetal 1b (2.12 g, 99%). |
| 96% |
In water for 0.0333333h; microwave irradiation; |
|
| 96% |
With polyaniline-sulfate salt In toluene for 0.75h; Heating; |
|
| 95% |
With phosphoric acid functionalized ethanolamine grafted polyacrylonitrile fiber In neat (no solvent) at 80℃; for 0.166667h; Green chemistry; |
|
| 95% |
With poly(vinylbenzyltrimethylammonium tribromide) resin at 20℃; for 0.25h; |
Representative procedure for the acetalization of benzaldehydes
General procedure: A mixture of 0.7g(5 mmol) of 1a, and 10 mL ethylene glycol or methanol was stirred for 5 min, andthen 0.021 g of PVBMATB resin (3 % weight of 1a) was added, and the mixture was stirred at room temperaturefor proper time. Afterward, the resin was recycled through filteration, and the organic layer wasextracted with toluene(15 mL) three times. The combined organic layer was dried over anhydrous Na2SO4.After filtration, the solvent was removed under reduced pressure, and the residual was treated with aluminachromatography (Petroleum ether/AcOEt = 20/1,v/v) to generate the product. |
| 94% |
With toluene-4-sulfonic acid In benzene for 12h; Heating; |
|
| 92% |
for 0.0333333h; microwave irradiation; |
|
| 92% |
With toluene-4-sulfonic acid In chloroform for 8h; Molecular sieve; Reflux; |
|
| 91% |
In cyclohexane for 7h; Heating; |
|
| 90% |
With iodine In tetrahydrofuran for 0.116667h; Irradiation; |
|
| 90% |
With iodine In tetrahydrofuran for 0.0166667h; microwave irradiation; |
|
| 90% |
With phosphorus pentoxide; silica gel at 20℃; |
|
| 87% |
With 1,3-bis(3,5-bis(trifluoro-ethyl)phenyl)thiourea; orthoformic acid triethyl ester at 25℃; for 11.5h; |
|
| 87% |
In toluene at 90℃; for 1h; |
|
| 86% |
With lanthanum(III) nitrate at 20℃; for 1.4h; |
|
| 85% |
With 4,4'-(propane-1,3-diyl)bis(1-methyl-1,4-diazabicyclo-[2.2.2]octane-1,4-diium) tetra-hydrogensulfate at 80℃; for 3h; |
|
| 84% |
With bismuth(lll) trifluoromethanesulfonate at 80℃; Neat (no solvent); |
|
| 84% |
With piloty's acid; triethylamine In dichloromethane at 20℃; for 0.166667h; |
|
| 84% |
With toluene-4-sulfonic acid In toluene for 6h; Reflux; Dean-Stark; |
4.3. 2-(4-Chlorophenyl)-1,3-dioxolane (11e)
A solution of 4-chlorobenzaldehyde (10e, 29.0 g, 0.20 mol), ethylene glycol (40 mL, 44.5 g, 0.72 mol) and p-toluenesulfonic acid (0.4 g, 0.002 mol) in toluene (120 mL) was refluxed in a Dean-Stark apparatus for 6 h. The reaction mixture was washed with aqueous sodium hydrogen carbonate solution (5 w/w%, 150 mL) and water (3 x 150 mL), dried over MgSO4 and the solvent was evaporated. The crude pale yellow oil was distilled under reduced pressure (0.2 bar) at 88-100 °C to give 11e (30.9 g, 84%) as a colorless oil. Analytical data are in accord with the literature. 33 |
| 81% |
With Kaolinitic clay In benzene for 2h; Heating; |
|
| 81% |
With natural kaolinitic clay In benzene for 2h; Heating; |
|
| 76% |
With bismuth(lll) trifluoromethanesulfonate In fluorobenzene at 110℃; for 5h; |
|
| 75% |
With dimethylbromosulphonium bromide; orthoformic acid triethyl ester at 20℃; for 0.333333h; |
|
| 75% |
With iodine at 20℃; Ionic liquid; |
|
| 74% |
With 9.0 wt% H4[SiW12O40] on SiO2 In neat (no solvent) at 60℃; for 6h; chemoselective reaction; |
|
| 73% |
With eosin y at 20℃; Inert atmosphere; Schlenk technique; Irradiation; |
Typical procedure for acetalization
General procedure: A 25-mL oven-dried Schlenk tube was sequentially added a mixture of aldehyde derivatives (0.5 mmol), dry CH3OH (2 mL), and Eosin Y (6.4 mg, 2 mol%). The tube was evacuated and backfilled with nitrogen (three times). The reaction mixture was stirred under a 16 W LED white lamp irradiation at a distance of 10 cm at room temperature for 12 h. The resulting mixture was diluted with EtOAc (8 mL). After completion of the reaction, phenylhydrazine was added to react with the excess benzaldehyde. The resulting crude product was washed with sodium hydroxide solution thrice. Subsequently, anhydrous sodium sulfate was added to remove water and the resulting mixture was filtered to collect the filtrate. The solvent in the filtrate was partially removed by rotary evaporation and the remaining product was purified by column chromatography (ethyl acetate/petroleum ether), followed by another round of rotary evaporation to afford the corresponding compounds. |
| 72% |
With toluene-4-sulfonic acid In toluene Heating; |
|
| 68% |
With sulfuric acid; silica gel at 20℃; for 0.5h; |
|
|
With sulfuric acid; xylene Unter Entfernen des entstehenden Wassers.; |
|
|
With 8-aminopyrene-1,3,6-trisulfonic acid, trisodium salt In toluene for 24h; Heating; |
|
| 95 % Spectr. |
In toluene at 109.85℃; for 6h; |
|
|
With 1-hexyl-3-methylimidazolium tetrafluoroborate at 130℃; for 3h; |
|
| 94 % Chromat. |
With air; propyl-sulfonic acid-functionalized FSM-16 mesoporous silica In toluene for 1h; |
|
|
With 1-methylimidazolium tetrafluoroborate at 90℃; for 6h; |
|
| 80 %Chromat. |
With zirconyl triflate In acetonitrile at 20℃; for 0.0333333h; chemoselective reaction; |
|
| 95 %Chromat. |
With [1-methylimidazolium]3[12-tungstophosphate] In toluene for 1.5h; Reflux; |
|
|
With mesoporous sulfated zirconia at 27℃; for 0.5h; Inert atmosphere; |
|
|
With fluorous silica gel-supported bis(perfluorooctanesulfonyl)imide In toluene for 2h; Reflux; |
3.4. Typical procedure for the synthesis of 1,3-dioxolanes
General procedure: A mixture of benzaldehyde (1 mmol), ethylene glycol (2 mmol) and toluene (3 mL) was stirred as FSG-HNPf2 (1 mol%) was added. The reaction mixture was heated at reflux for 2 h and then cooled to room temperature. Supported catalyst was recovered by filtration and washed with 1,2-dichloroethane (5 mL). FSG-HNPf2 was dried under vacuum for reuse in the next cycle. The reaction mixture was analyzed by GC and GC/MS. The crude residue was purified by column chromatography using silica gel with hexanes/ethyl acetate (20:1 to 5:1 gradient) as the eluent system. |
|
With toluene-4-sulfonic acid In benzene Dean-Stark; |
|
| 98 %Chromat. |
With 3H(1+)*O40SiW12(4-)*C21H22O3PS(1+) In cyclohexane for 1.5h; Dean-Stark; Reflux; |
The procedure for acetalization
General procedure: The mixture of aldehyde or ketone (0.1 mol), diol (0.1 mol), cyclohexane (10 mL) and the pseudo-IL (0.05 g) was magnetically stirred in a 50-mL three-necked flask. A Dean-Stark apparatus was used to remove the water continuously from the reaction mixture. The reaction was monitored by GC analysis with small samples from reaction mixture at half-an-hour intervals. On completion, the IL was separated automatically from the reaction system by cooling, which made the catalyst recovery quite simple. |
|
With toluene-4-sulfonic acid at 120℃; for 24h; |
|
|
With toluene-4-sulfonic acid In toluene Reflux; |
|
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