N,N,N¢¢,N¢¢-Tetra-n-butyl-N¢-(2-ethylhexyl)-guanidine (5e)
(Gua-4,4-i8-4,4). Prepared from N,N,N¢,N¢-tetra-n-
157.6 (CO3), 164.7 (CN3) ppm. MS (ESI+) m/z (%) = 242.2590
(100, C14H32N3 requires 242.2591, [cation]+). IR (neat) n = 2962
(m, nC–H), 2933 (m, nC–H), 2874 (m, nC–H), 1676 (s, nC O), 1538 (s,
nC N), 1439 (m), 1268 (vs, nC–O), 1064 (s, nC–O), 838 (m) cm-1.
butylchloroformamidinium chloride (17.10 g, 50.4 mmol,
1.00 eq.), triethylamine (5.6 g, 55.0 mmol, 1.09 eq.) and
2-ethylhexylamine (7.1 g, 55.0 mmol, 1.09 eq.). Fractional
distillation (129 ◦C/1.7 ¥ 10-1 mbar) gave the guanidine (19.58 g,
98%) as a colourless liquid. Anal. calc. for C25H53N3 (395.71 g
mol-1) C 75.88, H 13.50, N 10.62%; found C 76.03, H 13.45, N
10.64%. 1H NMR (300 MHz, CD3CN) d = 0.83–0.91 (m, 18H,
C4a,c-H, C6b-H and C8b-H), 1.18–1.45 (m, 25H, C2a,c-H,
C3a,c-H, C2b-H to C5b-H and C7b-H), 2.92–3.04 (m, 10H,
C1a-c-H) ppm; 13C NMR (75 MHz, CD3CN) d = 11.8 (C8b),
14.3, 14.4 (C4a,c), 14.5 (C6b), 21.0, 21.2 (C3a,c), 24.0 (C5b),
25.8 (C4b), 30.1 (C3b), 30.7, 31.7 (C2a,c), 32.6 (C7b), 43.3
(C2b), 48.4, 49.7 (C1a,c), 53.1 (C1b), 158.7 (CN3) ppm. MS
(ESI+) m/z (%) = 396.4311 (100, C25H54N3 requires 396.4312,
[M+H]+). IR (neat) n = 2956 (s, nC–H), 2926 (s, nC–H), 2859 (s,
N-(2-Ethylhexyl)-N¢,N¢,N¢¢,N¢¢-tetraethyl-N-methylguanidi-
nium methylcarbonate (6c) [Gua-i8,1-2,2-2,2](MeOCO2). Pre-
pared from N¢-(2-ethylhexyl)-N,N,N¢¢,N¢¢-tetraethylguanidine
(5c) (2.26 g, 10.01 mmol, 1.00 eq.) and dimethyl carbonate
(4.49 g, 4.2 mL, 49.84 mmol, 4.98 eq.): 2.81 g (95%) golden
yellow oil. Anal. calc. for C20H43N3O3 (373.57 g mol-1) C 64.30,
1
H 11.60, N 11.25%; found C 64.12, H 11.48, N 11.50%. H
NMR (300 MHz, CD3CN) d = 0.82–0.94 (m, 6H, C6a-H and
C8a-H), 1.02–1.49 (m, 20H, C1c-f-H, C3a-H to C5a-H, C7a-
H), 1.65–1.75 (m, 1H, C2a-H), 2.87 (s, 3H, C1b-H), 2.90–3.38
(m, 10H, C1a,c-f-H), 3.29 (s, 3H, OCH3) ppm; 13C NMR (75
MHz, CD3CN) d = 10.3, 11.4 (C8a, rotamers), 12.8, 12.9, 13.0,
13.1, 13.41, 13.43 (C2c-f, rotamers), 14.3, 14.4 (C6a, rotamers),
23.7, 23.9, 24.7, 24.8 (C4a and C5a, rotamers), 28.8, 29.6 (C3a,
rotamers), 31.2, 31.8 (C7a, rotamers), 37.3, 37.8 (C2a, rotamers),
39.4 (C1b), 44.1, 44.3, 44.56, 44.58, 44.9 (C1c-f, rotamers), 51.8
(OCH3), 57.4, 57.6 (C1a, rotamers), 157.6 (CO3), 165.2 (CN3)
ppm. MS (ESI+) m/z (%) = 298.3214 (100, C18H40N3 requires
298.3217, [cation]+). IR (neat) n = 2960 (m, nC–H), 2930 (m, nC–H),
2874 (m, nC–H), 1676 (s, nC O), 1537 (s, nC N), 1439 (m), 1268 (vs,
n
C–H), 1610 (vs, nC N), 1459 (m), 1399 (m), 1376 (m), 1285 (w),
1211 (m), 1110 (w), 730 (w) cm-1.
Pentaalkylmethylguanidinium methylcarbonates
General procedure for the preparation of pentaalkylmethyl-
guanidinium methylcarbonates (6). The appropriate pen-
taalkylguanidine (5) (1.0 eq.) and dimethyl carbonate (5–20 eq.)
were introduced into a Schlenk-tube with a PTFE valve and
degassed two times. The stirred mixture was then heated to
120 ◦C for three days. Excess dimethyl carbonate was removed
in vacuo, the crude product was washed two times with dry
pentane and finally dried in vacuo at 50 ◦C for at least one hour.
n
C–O), 1065 (s, nC–O), 839 (m) cm-1.
N,N,N¢,N¢,N¢¢-Penta-n-butyl-N¢¢-methylguanidinium methyl-
carbonate
(6d)
[Gua-4,4-4,4-4,1](MeOCO2). Prepared
from N,N,N¢,N¢¢,N¢¢-penta-n-butylguanidine (5d) (5.35 g,
15.75 mmol, 1.00 eq.) and dimethyl carbonate (7.09 g, 6.7 mL,
78.75 mmol, 5.00 eq.): 6.44 g (95%) golden yellow oil. Anal.
calc. for C24H51N3O3 (429.68 g mol-1) C 67.09, H 11.96, N
9.78%; found C 66.66, H 11.95, N 10.32%. 1H NMR (300
N,N,N¢,N¢,N¢¢-Pentaethyl-N¢¢-methylguanidinium methylcar-
bonate (6a) [Gua-2,2-2,2-2,1](MeOCO2). Prepared from
N,N,N¢,N¢¢,N¢¢-pentaethylguanidine (5a) (2.09 g, 10.5 mmol,
1.00 eq.) and dimethyl carbonate (5.0 mL, 59 mmol, 5.6 eq.):
2.87 g (94%) white powder. Anal. calc. for C14H31N3O3 (289.41 g
mol-1) C 58.10, H 10.80, N 14.52%; found C 58.01, H 10.81, N
14.76%. 1H NMR (300 MHz, CD3CN) d = 1.08–1.20 (m, 15H,
C2a-e-H), 2.83 (s, 3H, C1f-H), 3.03–3.31 (m, 10H, C1a-e-H),
3.27 (s, 3H, OCH3) ppm; 13C NMR (75 MHz, CD3CN) d = 13.00,
13.04, 13.2, 13.4 (C2a-e), 37.8 (C1f), 44.2, 44.4, 44.5, 44.8 (C1a-
d), 48.3 (C1e), 51.7 (OCH3), 157.5 (CO3), 164.7 (CN3) ppm. MS
(ESI+) m/z (%) = 214.2275 (100, C12H28N3 requires 214.2278,
[cation]+). IR (neat) n = 2972 (w, nC–H), 2935 (w, nC–H), 2890 (w,
3
MHz, CD3CN) d = 0.91, 0.92 (2 ¥ t, 15H, JHH = 7.2, 7.3 Hz,
C4a-e-H), 1.20–1.49 (m, 15H, C3a-e-H, C2a-e-Ha), 1.56–1.75
(m, 5H, C2a-e-Hb), 2.86 (s, 3H, C1f-H), 2.95–3.26 (m, 10H,
C1a-e-Ha and -Hb), 3.29 (s, 3H, OCH3) ppm; 13C NMR (75
MHz, CD3CN) d = 14.0 (C4a-e), 20.7 (C3e), 20.8 (C3a-d),
30.07, 30.09, 30.2, 30.4, 30.5 (C2a-e), 38.7 (C1f), 49.8, 50.1,
50.2, 50.6 (C1a-d), 51.8 (OCH3), 53.6 (C1e), 157.6 (CO3), 165.0
(CN3) ppm. MS (ESI+) m/z (%) = 354.3838 (100, C22H48N3
requires 354.3843, [cation]+); MS (ESI-) m/z (%) = 75.0090
(100, C2H3O3 requires 75.0088, [anion]-). IR (neat) n = 2956 (m,
n
C–H), 1671 (m, nC O), 1570 (m, nC N), 1538 (s, nC N), 1447 (m),
nC–H), 2931 (m, nC–H), 2872 (m, nC–H), 1676 (vs, nC O), 1534 (s,
1266 (vs, nC–O), 1063 (s, nC–O), 844 (s), 811 (m), 791 (m) cm-1.
nC N), 1457 (m), 1433 (m), 1269 (vs, nC–O), 1066 (s, nC–O), 841 (s)
cm-1.
N -n-Butyl-N¢,N¢,N¢¢,N¢¢-tetraethyl-N -methylguanidinium
methylcarbonate (6b) [Gua-4,1-2,2-2,2](MeOCO2). Prepared
from N¢-n-butyl-N,N,N¢¢,N¢¢-tetraethylguanidine (5b) (1.88 g,
8.27 mmol, 1.00 eq.) and dimethyl carbonate (4.49 g, 4.2 mL,
49.84 mmol, 6.03 eq.): 2.53 g (97%) golden yellow oil. Anal.
calc. for C16H35N3O3 (317.47 g mol-1) C 60.53, H 11.11, N
13.24%; found C 60.54, H 11.02, N 13.53%. 1H NMR (300 MHz,
CD3CN) d = 0.91 (t, 3H, 3JHH = 7.3 Hz, C4a-H), 1.08–1.17 (m,
12H, C2c-f-H), 1.21–1.36 (m, 2H, C3a-H), 1.43–1.72 (m, 2H,
C2a-H), 2.85 (s, 3H, C1b-H), 3.06–3.34 (m, 10H, C1a,c-f-H),
3.28 (s, 3H, OCH3) ppm; 13C NMR (75 MHz, CD3CN) d = 12.9,
13.1, 13.2, 13.4 (C2c-f), 14.0 (C4a), 20.7 (C3a), 30.0 (C2a), 38.6
(C1b), 44.2, 44.46, 44.61, 44.9 (C1c-f), 51.8 (OCH3), 53.4 (C1a),
N¢,N¢,N¢¢,N¢¢-Tetra-n-butyl-N-(2-ethylhexyl)-N-methylgua-
nidinium methylcarbonate (6e) [Gua-i8,1-4,4-4,4](MeOCO2).
Prepared from N,N,N¢¢,N¢¢-tetra-n-butyl-N¢-(2-ethylhexyl)-
guanidine (5e) (2.80 g, 7.07 mmol, 1.00 eq.) and dimethyl
carbonate (5.35 g, 5.0 mL, 59.3 mmol, 8.39 eq.): 2.91 g (85%)
pale yellow oil. Anal. calc. for C28H59N3O3 (485.79 g mol-1) C
69.23, H 12.24, N 8.65%; found C 69.14, H 11.99, N 9.25%.
1H NMR (300 MHz, CD3CN) d = 0.82–0.95 (m, 18H, C4c-f-
H, C6a-H and C8a-H), 1.02–1.49 (m, 20H, C3c-f-H, C2c-f-Ha,
C3a-H to C5a-H, C7a-H), 1.50–1.79 (m, 5H, C2a-H, C2c-f-Hb),
2.87 (s, 3H, C1b-H), 2.90–3.31 (m, 10H, C1a,c-f-H), 3.29 (s, 3H,
OCH3) ppm; 13C NMR (75 MHz, CD3CN) d = 10.6, 11.2 (C8a,
614 | Green Chem., 2011, 13, 608–618
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