Inorganic Chemistry
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(COCCHCHCHCHCH)2), 7.9 (d, 4H, (COCCHCHCHCHCH)2).
13C NMR (δc, 400 MHz, CDCl3) 10.60 (1C, CH2CH2CH3), 14.16
(1C, CHCH2CH3), 23.23 (1C, alkyl), 24.09 (1C, alkyl), 28.32 (1C,
alkyl), 31.02 (1C, alkyl), 36.66 (1C, CH2CHCH2), 52.66 (1C,
NCH2C), 57.17 (2C, (NCH2N)2), 127.10 (4C, aromatic), 128.62 (4C,
aromatic), 131.73 (2C, aromatic), 134.06 (2C, CCON), 168.49 (2C,
NCO). m/z (ESI) 396 [M + H]+.
30.05 (2C, N(CH2CHCH2CH3)2), 31.11 (2C, N(CH2CHCH2CH3)2),
37.21 (2C, N(CH2)2), 37.22 (2C, alkyl), 46.97 (1C, CHCH3), 50.74
(1C, COCH2CH), 57.04 (1C, COCH2CH), 58.60 (1C, NHCH2N),
172.68 (1C, CO). m/z (ESI) 422 [M + H]+.
N-[(Di-n-cyclohexylamino)methyl]benzamide (L7).23−25 To a
rapidly stirring slurry of (benzamidomethyl)triethylammonium
chloride (4.00 g, 0.015 mol) in tetrahydrofuran (60 mL) was added
di-n-cyclohexylamine (3.28 mL, 0.016 mol) in one portion, and the
reaction mixture was allowed to heat at 70 °C for 45 min, and then
concentrated in vacuo. The mixture was then redissolved in dichloro-
methane (50 mL) and washed with 4 × 50 mL portions of saturated
sodium carbonate solution. The organic layer was dried over magnesium
sulfate and then concentrated in vacuo and purified by trituration with
N-[(Di-n-hexylamino)methyl]benzamide (L4).23−25 To a rap-
idly stirring slurry of (benzamidomethyl)triethylammonium chloride
(2.45 g, 9.0 × 10−3 mol) in tetrahydrofuran (60 mL) was added
dihexylamine (2.09 mL, 9.0 × 10−3 mol) in one portion. The reaction
mixture was heated to reflux for 45 min and then concentrated
in vacuo. The reaction mixture was redissolved in dichloromethane
(50 mL) and washed with 2 × 50 mL portions of saturated sodium
carbonate solution. The organic layer was dried over magnesium
sulfate and then concentrated in vacuo, and the resulting golden oil was
purified by flash column chromatography (silica, 9:1 dichloromethane/
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diethylether to yield a colorless solid. Yield = 4.65 g (55%). H NMR
(δH, 500 MHz, CDCl3) 1.1 (m, 2H, NCHCH2CH2CHaHb), 1.3 (m, 8H,
NCHCH2CH2), 1.6 (d, 2H, NCHCH2CH2CHaHb), 1.8 (m, 8H,
NCHCH2CH2), 2.7 (m, 2H, NCH), 4.5 (d, 2H, NCH2NH), 6.0 (s, 1H,
NH), 7.4 (t, 2H, COCCHCHCHCHCH-aromatic), 7.5 (t, 1H, COC-
CHCHCHCHCH-aromatic), 7.8 (d, 2H, COCCHCHCHCHCH-
aromatic). 13C NMR (δC, 400 MHz, CDCl3) 25.98 (2C, (cy-C6H11)2),
26.29 (4C, (cy-C6H11)2), 32.88 (4C, (cy-C6H11)2), 54.84 (2C, (cy-
C6H11)2), 58.60 (1C, NCH2−N), 126.79 (2C, aromatic), 128.55 (2C,
aromatic), 131.25 (1C, aromatic), 135. 00 (1C, aromatic), 166.69 (1C,
CO). m/z (ESI) 314.2 [M]+. Anal. Calcd for C20H30N2O: C 76.39,
H 9.62, N 8.91. Found: C 75.35, H 9.34, N 8.80.
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methanol). Yield = 1.16 g (41%). H NMR (δH, 400 MHz, CDCl3)
0.89 (t, 6H, (CH2CH2CH3)2), 1.29 (m, 12H, (CH2CH2CH2CH2CH3)2),
1.53 (m, 4H, N(CH2CH2CH2)2, 2.55 (t, 4H, N(CH2CH2CH2)2),
4.41 (d, 2H, NHCH2N), 6.60 (t, 1H, NHCH2N), 7.42 (t, 2H,
COCCHCHCHCHCH), 7.49 (m, 1H, COCCHCHCHCHCH), 7.79
(m, 2H, COCCHCHCHCHCH). 13C NMR (δC, 400 MHz, CDCl3)
14.06 (2C, alkyl), 22.67 (2C, alkyl), 27.15 (2C, alkyl), 27.66 (2C, alkyl),
31.76 (2C, alkyl), 52.14 (2C, alkyl), 58.77 (1C, alkyl), 126.94 (2C,
aromatic), 128.54 (2C, aromatic), 131.46 (1C, aromatic), 134.69 (1C,
aromatic), 167.92 (1C, CO). m/z (ESI) 319 [M + H]+.
N-[(Di-n-hexylamino)methyl]-3,5,5-trimethylhexanamide
(L5).26 3,5,5-Trimethylhexanamide (4.00 g, 2.5 × 10−3 mol) was
dissolved in the minimum amount of methanol and cooled to 0 °C.
Formaldehyde (2.06 g, 0.025 mol) and di-n-hexylamine (4.71 g, 0.025
mol) were added, and the reaction was warmed to 40 °C and allowed
to stir for 6 days. After this time the reaction mixture was concentrated
in vacuo, and the resulting golden oil was purified by flash column
chromatography (silica, 96:4:0.3 dichloromethane/methanol/aqueous
ammonia (35%)). Yield = 5.4 g (65%). 1H NMR (δH, 400 MHz,
CDCl3) 0.88 (t, 6H, N(CH2CH2CH2CH2CH2CH3)2), 0.91 (s, 9H,
COCH2CHCH2C(CH3)3), 0.98 (d, 3H, COCH2CHCH3), 1.12−1.23
(m, 4H, COCH2CHCH2), 1.27 (m, 12H, N[CH2CH2CH2CH2C-
H2CH3]2), 1.45 (m, 4H, N(CH2CH2)2), 2.0 (m, 1H, NHCOCH2CH),
1.95−2.22 (dq, 2H, NHCOCH2CH), 2.44 (t, 4H, N(CH2CH2)2), 4.18
(d, 2H, NHCH2N), 5.73 (t, 1H, NH). 13C NMR (δC, 400 MHz, CDCl3)
14.05 (3C, C(CH3)3), 22.57 (2C, N(CH2CH2CH2CH2CH2CH3)2),
22.65 (2C, N(CH2CH2CH2CH2CH2CH3)2), 27.15 (2C, N(CH2CH2-
CH2CH2)2), 27.67 (1C, CHCH2C), 30.04 (2C, N(CH2CH2CH2)2),
31.05 (1C, COCH2CHCH3), 31.76 (2C, N(CH2CH2)2), 46.94 (1C,
COCH2CHCH3), 50.7 (2C, N(CH2)2), 52.08 (1C, COCH2CH), 57.90
(1C, COCH2CH), 58.02 (1C, NHCH2N), 172.78 (1C, NCO). m/z
(ESI) 355 [M + H]+.
N-[Di-n-propylamino methyl] benzamide (L8).23−25 A stirred
suspension of (benzamidomethyl)triethylammonium chloride (2.5 g,
9.3 × 10−3 mol) in distilled water (60 mL) was heated until dissolved.
To this solution was added di-n-propylamine (1.51 mL, 1.0 × 10−3
mol) in one portion, and the reaction mixture was allowed to stir for
30 min. The resultant colorless precipitate was collected by vacuum
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filtration. Yield = 1.35 g (57%). H NMR (δH, 400 MHz, CDCl3) 0.9
(t, 6H, N(CH2CH2CH3)2), 1.6 (m, 4H, N(CH2CH2)2), 2.5 (t, 4H,
N(CH2CH2)2), 4.4 (d, 2H, NCH2NH), 6.4 (t, 1H, NH), 7.4 (t, 2H,
COCCHCHCHCHCH-aromatic), 7.5 (t, 1H, COCCHCHCHC-
HCH-aromatic), 7.8 (d, 2H, COCCHCHCHCHCH-aromatic). 13C
NMR (δC, 400 MHz, CDCl3) 11.91 (2C, NCH2CH2CH3), 20.94
(2C, NCH2CH2CH3), 54.17 (2C, NCH2CH2CH3), 58.90 (1C,
N−CH2−N), 126.90 (2C, aromatic), 128.62 (2C, aromatic), 131.51
(1C, aromatic), 134. 72 (1C, aromatic), 167.82 (1C, CO). m/z (ESI)
234 [M + H]+.
General Extraction Procedures. Analytical-grade toluene was
used as the water-immiscible solvent for the extractants and deionized
water for the metal chloride solutions. Inductively coupled plasma
optical emission spectroscopy (ICP-OES) calibration standards for zinc
were prepared by dilution of commercially available standards from
Aldrich. Extractions were performed by vigorously stirring solutions
with magnetic stir bars in sealed vials for 1 h at room temperature. All
volumes were measured by using 1 and 5 mL Rainin edp3 automatic
pipettes. ICP-OES was carried out on a Perkin-Elmer Optima 5300 DV,
employing an radio frequency (RF) forward power of 1400 W, with
argon gas flows of 15, 0.2, and 0.75 L min−1 for plasma, auxiliary, and
nebulizer flows, respectively. Using a peristaltic pump, sample solutions
were taken up into a Gem Tip cross-flow nebulizer and Scotts spray
chamber at a rate of 1.50 mL min−1.
Dependence of Zn(II) Loading on pH. A series of aqueous
solutions of ZnCl2 (0.01 M) were prepared by adding 2.5 mL of ZnCl2
solution (0.02 M ZnCl2 in 6 M LiCl) to variable volumes of HCl
solution (6 or 0.1 M) and making up to 5 mL with 6 M LiCl solution.
These solutions, with pH ranging between −2 < pH < 6, were
contacted with an equal volume of 0.01 M extractant solution in
toluene and stirred at room temperature. After one hour the phases
were allowed to separate and a 1 mL aliquot of the organic phase was
transferred to a 10 mL volumetric flask; the toluene was removed by
evaporation in vacuo and the flask made up to the mark with butan-1-
ol for ICP-OES analysis. The equilibrium pH of the aqueous phase was
recorded using a pH meter.
N-[Bis(2-ethylhexyl)amino]methyl-3,5,5-trimethylhexana-
mide (L6).26 In a round-bottom flask 3,5,5-trimethylhexanamide
(2.00 g, 1.3 × 10−3 mol) was dissolved in the minimum amount of
methanol and cooled to 0 °C. To this were added formaldehyde
(1.031 g, 1.3 × 10−3 mol) and di-2-ethylhexylamine (3.067 g, 1.3 ×
10−3 mol). The reaction was warmed to 40 °C and allowed to stir for
6 days at this temperature. After this time the reaction mixture was
concentrated in vacuo, and the resulting golden oil was purified by flash
column chromatography (silica, 99:1:0.1 dichloromethane/methanol/
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aqueous ammonia (35%)). Yield = 2.78 g (57%). H NMR (δH, 400
MHz, CDCl3) 0.84 (t, 4H, N(CH2CHCH2CH3CH2CH2CH2CH3)2),
0.88 (m, 4H, N(CH2CH)2), 0.93 (d, 6H, N(CH2CHCH2CH3CH2-
CH2CH2CH3)2), 0.99 (m, 3H,COCH2CHCH3), 1.14−1.36 (m, 1H,
COCH2CHCH3), 1.27 (m, 27H, N(CH2CHCH2CH3CH2-
CH2CH2CH3)2 and COCH2CHCH2C(CH3)3), 1.92−2.21 (dq, 2H,
N(CH2CHCH2CH3)2), 2.25 (dd, 4H, NHCOCH2CHCH2), 4.15 (d,
2H, NHCH2N), 5.61 (t, 1H, NH). 13C NMR (δC, 400 MHz, CDCl3)
10.71 (1C, CH2C(CH3)3), 14.13 (3C, CH2C(CH3)3), 22.59 (2C,
N(CH2CHCH2CH2CH2CH3)2), 23.22 (2C, N(CH2CHCH2-
CH2CH2CH3)2), 24.25 (2C, N(CH2CHCH2CH2CH2CH3)2),
27.27 (1C, COCH2CHCH2), 28.97 (2C, N(CH2CHCH2CH3)2),
Dependence of Zn(II) Loading on Ligand Concentration.
Solutions of extractants were prepared at concentrations ranging
between 0.004 and 0.01 M by adding aliquots of a 0.05 M solution in
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dx.doi.org/10.1021/ic301691d | Inorg. Chem. 2012, 51, 12805−12819