Catalysis Science & Technology
Paper
Synthesis of dimethyl Isoidide (DMIi)
6.84 mmol, 1.0 mol eq.) were reacted in 20 mL of acetonitrile,
at 80 °C for 42 h. After cooling, the reaction crude was
filtered and concentrated under vacuum via rotavapor.
The products were obtained as pure via chromatographic
column (n-hexane/EtOAc 7/3; RfMCI1 = 0.3, RfMCI2 = 0.2).
The pure MCI1 was isolated as a white solid in 33% yield
(0.49 g). 1H NMR (400 MHz CDCl3) δ ppm = 5.17–5.15 (m,
1H), 4.68 (t, 1H), 4.57–4.55 (m, 1H), 4.35 (m, 1H), 4.17–4.14
(dd, 1H), 4.06–4.02 (dd, 1H), 3.94–3.90 (m, 1H), 3.80 (s, 3H),
3.63–3.59 (m, 1H). 13C NMR (100 MHz, CDCl3) δ ppm = 154.7,
85.4, 81.9, 81.6, 73.6, 73.3, 72.3, 55.1. HRMS: m/z [M + H]+
calc. for [C8H12O6 + H]+: 205.0707; found: 205.0706.
The pure MCI2 was isolated as a white solid in 16% yield
(0.23 g). 1H NMR (400 MHz CDCl3) δ ppm = 5.11–5.07(m,
1H), 4.93–4.91 (t, 1H), 4.44–4.43 (d, 1H), 4.38–4.36 (m, 1H),
3.95 (m, 2H), 3.93–3.86 (m, 2H), 3.84 (s, 3H). 13C NMR (100
MHz, CDCl3) δ ppm = 155.2, 88.4, 80.4, 76.9, 76.3, 75.7, 70.4,
55.1. HRMS: m/z [M + H]+ calc. for [C8H12O6 + H]+: 205.0707;
found: 205.0706.
In an autoclave, 1.00 g of isoidide (6.84 mmol, 1.00 mol eq.)
was reacted with 30 mL of dimethyl carbonate (0.35 mol,
50.00 mol eq.) in presence of 0.29 g of N-methyl pyrrolidine
as base (3.41 mmol, 0.50 mol eq.), at 200 °C for 12 h. The
autogenous pressure reached the value of 20 bar.
After cooling, the reaction crude was filtered and
concentrated under vacuum via rotavapor. The resulting
mixture was analysed via GC-MS to evaluate conversion of the
substrate and products selectivity.
The product was obtained as pure via chromatographic
column (Et2O/n-hexane 1/1; Rf = 0.30). The pure compound
was isolated as a yellowish liquid.
1H NMR (400 MHz CDCl3) δ ppm = 4.61 (s, 2H), 3.91–3.83
(m, 6 H), 3.40 (s, 6H). 13C NMR (100 MHz, CDCl3) δ ppm =
85.1, 84.9, 71.8, 57.2.
Synthesis of dimethyl Isomannide (DMIm)
In an autoclave, 1.00 g of isoidide (6.84 mmol, 1.0 mol eq.)
was reacted with 30 mL of dimethyl carbonate (0.35 mol, 50.0
mol eq.) in presence of 0.29 g of N-methyl pyrrolidine as base
(3.41 mmol, 0.5 mol eq.), at 200 °C for 12 h. The autogenous
pressure reached the value of 20 bar.
After cooling, the reaction crude was filtered and
concentrated under vacuum via rotavapor. The resulting
mixture was analysed via GC-MS to evaluate conversion of the
substrate and products selectivity.
Synthesis of monomethyl isosorbides – MMI1 and MMI2
To a solution of D-isosorbide (1.00 g, 6.84 mmol) in THF (30
mL), NaH 60% w/w (0.27 g, 6.84 mmol) was added under N2
atmosphere. Then the mixture was cooled to 0 °C and a
solution of CH3I (0.43 mL, 6.84 mmol) in THF (10 mL) was
added dropwise within 15 min. The ice bath was removed,
and the mixture was heated to 60 °C for 20 h under stirring.
The mixture at this point appears as a clear orange solution.
This solution was quenched with MeOH (2 mL) and
concentrated under vacuum to give a crude product.
The product was obtained as pure via chromatographic
column (Et2O/n-hexane 6/4; Rf = 0.40). The pure compound
was isolated as an amber coloured solid.
1H NMR (400 MHz CDCl3) δ ppm = 4.53 (m, 2H), 4.01 (t,
2H), 3.90 (m, 2H), 3.63 (t, 2H), 3.40 (s, 6H). 13C NMR (100
MHz, CDCl3) δ ppm = 81.9, 80.3, 70.9, 58.3.
The products were obtained as pure via chromatographic
column (DCM/MeOH 7/3; RfMMI1 = 0.3, RfMMI2 = 0.2).
The pure MMI1 was isolated as a yellow oil in 35% yield
1
(0.39 g). H NMR (400 MHz CDCl3) δ ppm = 4.53 (t, 1H), 4.40
(d, 1H), 4.21 (m, 1H), 4.01–3.97 (m, 1H), 3.85 (dd, 1H), 3.84–
3.77 (m, 2H), 3.53–3.49 (m, 1H), 3.32 (s, 3H). 13C NMR (100
MHz, CDCl3) δ ppm = 85.6, 85.4, 81.7, 73.6, 73.0, 72.2, 57.2.
HRMS: m/z [M + H]+ calc. for [C7H12O4 + H]+: 161.0808;
found: 161.0812.
Synthesis of dicarboxymethyl isosorbide (DCI)
In a 250 mL double-necked bottom round flask equipped
with a Dean–Stark trap and condenser, 5 g of isosorbide
(34.21 mmol, 1.0 mol eq.) was reacted with 90 mL of
dimethyl carbonate (1.07 mol, 30.0 mol eq.) in presence of
K2CO3 as base (0.95 g, 6.80 mmol, 0.2 mol eq.), at 90 °C for 6
h. After cooling, the reaction crude was filtered and
concentrated under vacuum via rotavapor to achieve DCI.
The pure MMI2 was isolated as a pale-yellow oil in 15%
1
yield (0.16 g). H NMR (400 MHz CDCl3) δ ppm = 4.67 (t, 1H),
4.40–4.38 (m, 1H), 4.27–4.25 (m, 1H), 3.92–3.85 (m, 4H),
3.54–3.48 (m, 1H), 3.41 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
ppm = 88.4, 81.8, 79.8, 76.8, 75.9, 70.0, 58.3. HRMS: m/z [M +
H]+ calc. for [C7H12O4 + H]+: 161.0808; found: 161.0812.
A
pure sample of DCI was obtained as via
chromatographic column (DCM/MeOH 99/4; Rf = 0.50).
1H NMR (400 MHz CDCl3) δ ppm = 5.13–5.12 (m, 1H),
5.10–5.08 (t, 1H), 4.92–4.89 (t, 1H), 4.57–4.56 (d, 1H), 4.12–
4.02 (m, 2H), 3.97–3.89 (m, 2H), 3.84 (s, 3H), 3.83 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ ppm = 155.1, 154.8, 85.9, 81.2, 80.8,
76.7, 73.2, 70.5, 55.1, 55.1. HRMS: m/z [M + H]+ calc. for
[C10H14O8 + H]+: 263.0761; found: 263.0766.
Synthesis of monomethylcarboxy methyl isosorbide – MCMI1
MMI2 (0.20 g, 1.25 mmol, 1.0 mol eq.), dimethyl carbonate
(7.50 mL, 89.10 mmol, 72.0 mol eq.), K2CO3 (0.35 g, 2.50
mmol, 2.0 mol eq.) were reacted at 90 °C for 24 h, in a 25 mL
bottom round flask. After 24 h, potassium carbonate (0.175 g,
1.25 mmol, 1.0 mol eq.) was added to mixture reaction and it
was left for another 24 h. After cooling, the reaction crude
was filtered and concentrated under vacuum via rotavapor.
Synthesis of monocarboxymethyl isosorbides MCI1 and MCI2
Isosorbide (1.00 g, 6.84 mmol, 1.0 mol eq.), dimethyl
carbonate (2.88 mL, 34.20 mmol, 5.0 mol eq.), K2CO3 (0.95 g,
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