4. Quench the reaction by slow addition (CAUTION! Hydrogen
might develop at this stage) of aqueous 1 N HCl (50 mL) and,
using a separatory funnel, extract the aqueous phase with DCM
(2 Â 100 mL).
5. After separation, combine the organic phases, wash then with
aqueous 1N HCl (3 Â 100 mL) and then evaporate DCM at
the rotavapor.
6. Dissolve the residue in a flask with the minimum amount of
DCM and add MeOH until a white precipitate starts to form.
Leave the flask overnight in the fridge to induce the complete
precipitation.
7. Filter the solid on a Buchner, wash it abundantly with MeOH,
and dry it under vacuum to obtain the product as a white solid
(3.05 g, 80% yield) (see Note 3).
8. Check the purity of the final compound by ESI-MS and
1 H
NMR. It is possible to compare the collected spectra with the
characterization data of the compound as reported in ref. 73.
3.1.2 Synthesis of
25,26,27,28tetrahexyloxycalix[4]
arene (3)
1. Put into a two-necked round-bottom flask p-tert-butyl-tetrahexyloxycalix[4]arene 2 (3 g, 3.04 mmol) and NaNO 3 (10.3 g,
120 mmol).
2. Add TFA (14 mL, 0.18 mol) dropwise upon stirring (see Note
4). The mixture becomes black and then yellow/orange. The
reaction is stirred at room temperature for 24 h (see Note 5).
3. Quench the reaction by addition of water (200 mL) and extract
the aqueous phase with DCM (2 Â 100 mL).
4. Wash the combined organic layers with water (150 mL) and
dry the organic solution over anhydrous MgSO 4 (see Note 6).
5. Remove the organic solvent from the filtrate at a rotavapor, add
MeOH (50 mL) and accurately triturate the residue to obtain
the pure product as a pale yellow powder (2.3 g, 81%).
6. Check the purity of the final compound by ESI-MS and
1 H
NMR. It is possible to compare the collected spectra with the
characterization data of the compound as reported [59].
3.1.3 Synthesis of
25,26,27,28tetrahexyloxycalix[4]
arene (4)
1. Into a two-necked round-bottom flask suspend tetranitro-tetrahexyloxycalix[4]arene 3 (500 mg, 0.53 mmol) in EtOH
(10 mL) and add NH 2 NH 2 ·H 2 O (0.52 mL, 10.6 mmol) and
Pd/C (10%) (catalytic amount).
2. Reflux the reaction mixture under stirring for 24 h equipping
the central neck with a bubble condenser (see Note 7).
3. At the end of the reaction, filter the catalyst off (see Note 8),
wash abundantly the retained solid and the filters with DCM
(20 mL), and combine the filtrates.
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Alessia Finotti et al.
might develop at this stage) of aqueous 1 N HCl (50 mL) and,
using a separatory funnel, extract the aqueous phase with DCM
(2 Â 100 mL).
5. After separation, combine the organic phases, wash then with
aqueous 1N HCl (3 Â 100 mL) and then evaporate DCM at
the rotavapor.
6. Dissolve the residue in a flask with the minimum amount of
DCM and add MeOH until a white precipitate starts to form.
Leave the flask overnight in the fridge to induce the complete
precipitation.
7. Filter the solid on a Buchner, wash it abundantly with MeOH,
and dry it under vacuum to obtain the product as a white solid
(3.05 g, 80% yield) (see Note 3).
8. Check the purity of the final compound by ESI-MS and
1 H
NMR. It is possible to compare the collected spectra with the
characterization data of the compound as reported in ref. 73.
3.1.2 Synthesis of
25,26,27,28tetrahexyloxycalix[4]
arene (3)
1. Put into a two-necked round-bottom flask p-tert-butyl-tetrahexyloxycalix[4]arene 2 (3 g, 3.04 mmol) and NaNO 3 (10.3 g,
120 mmol).
2. Add TFA (14 mL, 0.18 mol) dropwise upon stirring (see Note
4). The mixture becomes black and then yellow/orange. The
reaction is stirred at room temperature for 24 h (see Note 5).
3. Quench the reaction by addition of water (200 mL) and extract
the aqueous phase with DCM (2 Â 100 mL).
4. Wash the combined organic layers with water (150 mL) and
dry the organic solution over anhydrous MgSO 4 (see Note 6).
5. Remove the organic solvent from the filtrate at a rotavapor, add
MeOH (50 mL) and accurately triturate the residue to obtain
the pure product as a pale yellow powder (2.3 g, 81%).
6. Check the purity of the final compound by ESI-MS and
1 H
NMR. It is possible to compare the collected spectra with the
characterization data of the compound as reported [59].
3.1.3 Synthesis of
25,26,27,28tetrahexyloxycalix[4]
arene (4)
1. Into a two-necked round-bottom flask suspend tetranitro-tetrahexyloxycalix[4]arene 3 (500 mg, 0.53 mmol) in EtOH
(10 mL) and add NH 2 NH 2 ·H 2 O (0.52 mL, 10.6 mmol) and
Pd/C (10%) (catalytic amount).
2. Reflux the reaction mixture under stirring for 24 h equipping
the central neck with a bubble condenser (see Note 7).
3. At the end of the reaction, filter the catalyst off (see Note 8),
wash abundantly the retained solid and the filters with DCM
(20 mL), and combine the filtrates.
130
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