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S. Biradar et al. / Dyes and Pigments 125 (2016) 249e258
2.6. Synthesis of 4-amino-2’-butylazobenzenes 19e22
2.7.1. 2-Butyl-4’-methoxyazobenzene (30)
Yield 82%; 1H NMR (CDCl3)
d
¼ 0.94 (t, J ¼ 7.5 Hz, 3H), 1.40 (sex,
To water-DMF 1:3 mixed solvent (10 mL) were added 2-
butylaniline (A(2-Bu), 300 mg, 2.0 mmol) and conc. hydrochloric
acid (0.6 mL, 6.0 mmol). The mixture was stirred at 0 ꢁC for 10 min.
To the mixture was added sodium nitrite (140 mg, 2.0 mmol) and
stirred at 0 ꢁC for 1 h. To the mixture was added a sodium anili-
nomethanesulfonate (E, 2.0 mmol) and stirred at 0 ꢁC overnight.
After the reaction was completed, the resulting precipitate was
washed with water and heated in 10% aqueous sodium hydroxide
solution (50 mL) at 60 ꢁC for 2 h. The product was extracted with
ethyl acetate and purified by column chromatography (SiO2, AcOEt:
C6H14 ¼ 1: 30).
J ¼ 7.5 Hz, 2H), 1.67 (quin, J ¼ 7.5 Hz, 2H), 3.13 (t, J ¼ 7.5 Hz, 2H), 3.89
(s, 3H), 7.03 (d, J ¼ 9.2 Hz, 2H), 7.27 (t, J ¼ 8.0 Hz, 1H), 7.34 (t,
J ¼ 8.0 Hz, 1H), 7.36 (d, J ¼ 8.0 Hz, 1H), 7.63 (d, J ¼ 8.0 Hz, 1H), 7.92
(d, J ¼ 9.2 Hz, 2H); 13C NMR (CDCl3)
d
¼ 14.0, 22.5, 31.1, 34.3, 55.5,
114.1 (2C), 115.2, 124.7 (2C), 126.4, 130.3, 130.4, 142.3, 147.4, 150.3,
161.8; EIMS (70 eV) m/z (rel intensity) 268 (Mþ; 79), 122 (100);
Anal. Found: C, 76.36; H, 7.49; N, 10.50%. Calcd for C17H20N2O: C,
76.09; H, 7.51; N, 10.44%.
2.7.2. 2-Butyl-4’-ethoxyazobenzene (31)
Yield 87%; 1H NMR (CDCl3)
d
¼ 0.92 (t, J ¼ 7.6 Hz, 3H), 1.38 (sex,
J ¼ 7.6 Hz, 2H), 1.45 (t, J ¼ 7.1 Hz, 3H), 1.65 (quin, J ¼ 7.6 Hz, 2H), 3.11
2.6.1. 4-Amino-2’-butylazobenzene (19)
(t, J ¼ 7.6 Hz, 2H), 4.09 (q, J ¼ 7.1 Hz, 2H), 7.00 (d, J ¼ 9.2 Hz, 2H),
Yield 8%; 1H NMR (CDCl3)
d
¼ 0.91 (t, J ¼ 7.3 Hz, 3H), 1.38 (sex,
7.23e7.34 (m, 3H), 7.61 (d, J ¼ 7.8 Hz,1H), 7.90 (d, J ¼ 9.2 Hz, 2H); 13
C
J ¼ 7.3 Hz, 2H), 1.65 (quin, J ¼ 7.3 Hz, 2H), 3.10 (t, J ¼ 7.3 Hz, 2H), 4.01
(s, 2H), 6.74 (d, J ¼ 9.2 Hz, 2H), 7.21e7.31 (m, 3H), 7.59 (d, J ¼ 8.2 Hz,
NMR (CDCl3)
d
¼ 14.0, 14.8, 22.5, 31.1, 34.3, 63.8, 114.6 (2C), 115.3,
124.8 (2C), 126.4, 130.3, 130.4, 142.3, 147.3, 150.4, 161.3; EIMS
(70 eV) m/z (rel intensity) 282 (Mþ; 65), 239 (39), 136 (100), 108
(97); Anal. Found: C, 76.45; H, 8.05; N, 10.13%. Calcd for C18H22N2O:
C, 76.56; H, 7.85; N, 9.92%.
2H), 7.80 (d, J ¼ 9.2 Hz, 2H); 13C NMR (CDCl3)
d
¼ 14.0, 22.6, 31.1,
34.2, 114.6 (2C), 115.3, 125.1 (2C), 126.4, 129.8, 130.3, 141.8, 146.1,
149.3, 150.6; EIMS (70 eV) m/z (rel intensity) 253 (Mþ; 24), 148 (51),
107 (83), 92 (100); Anal. Found: C, 75.98; H, 7.70; N, 16.32%. Calcd
for C16H19N3: C, 75.85; H, 7.56; N, 16.59%.
2.7.3. 2-Butyl-4’-propyloxyazobenzene (32)
Yield 90%; 1H NMR (CDCl3)
d
¼ 0.92 (t, J ¼ 7.5 Hz, 3H), 1.06 (t,
2.6.2. 4-Amino-2’-butyl-2-methylazobenzene (20)
J ¼ 7.4 Hz, 3H), 1.38 (sex, J ¼ 7.5 Hz, 2H), 1.65 (quin, J ¼ 7.5 Hz, 2H),
1.84 (sex, J ¼ 7.4 Hz, 2H), 3.11 (t, J ¼ 7.5 Hz, 2H), 4.00 (t, J ¼ 7.4 Hz,
2H), 7.00 (d, J ¼ 8.9 Hz, 2H), 7.21e7.37 (m, 3H), 7.61 (d, J ¼ 7.8 Hz,
Yield 52%; 1H NMR (CDCl3)
d
¼ 0.92 (t, J ¼ 7.8 Hz, 3H), 1.38 (sex,
J ¼ 7.8 Hz, 2H), 1.66 (quin, J ¼ 7.8 Hz, 2H), 2.67 (s, 3H), 3.11 (t,
J ¼ 7.8 Hz, 2H), 3.94 (s, 2H), 6.52 (d, J ¼ 8.7 Hz, 1H), 6.58 (d,
J ¼ 8.7 Hz, 1H), 7.21e7.31 (m, 3H), 7.60 (d, J ¼ 8.7 Hz, 1H), 7.64 (d,
1H), 7.90 (d, J ¼ 8.9 Hz, 2H); 13C NMR (CDCl3)
d
¼ 10.5, 14.0, 22.5
(2C), 31.1, 34.3, 69.8, 114.7 (2C), 115.3, 124.7 (2C), 126.4, 130.3, 130.4,
142.3, 147.3, 150.4, 161.4; EIMS(70 eV) m/z (rel intensity) 296 (Mþ;
11), 253 (12), 135 (24), 108 (100); Anal. Found: C, 77.27; H, 8.20; N,
9.29%. Calcd for C19H24N2O: C, 76.99; H, 8.16; N, 9.45%.
J ¼ 8.7 Hz, 1H); 13C NMR (CDCl3)
¼ 14.0, 17.8, 22.6, 31.2, 34.3, 112.9,
d
115.6, 115.9, 117.5, 126.3, 129.5, 130.3, 141.0, 141.9, 144.1, 149.1, 150.9;
EIMS(70 eV) m/z (rel intensity) 267 (Mþ; 37), 149 (39), 120 (54), 106
(100); Anal. Found: C, 76.52; H, 8.13; N, 15.35%. Calcd for C17H21N3:
C, 76.37; H, 7.92; N, 15.72%.
2.7.4. 4-Butoxy-2’-butylazobenzene (33)
Yield 92%; 1H NMR (CDCl3)
d
¼ 0.92 (t, J ¼ 7.5 Hz, 3H), 0.99 (t,
2.6.3. 4-Amino-2’-butyl-2,5-dimethylazobenzene (21)
J ¼ 7.5 Hz, 3H), 1.39 (sex, J ¼ 7.5 Hz, 2H), 1.52 (sex, J ¼ 7.5 Hz, 2H),
1.65 (quin, J ¼ 7.5 Hz, 2H), 1.81 (quin, J ¼ 7.5 Hz, 2H), 3.11 (t,
J ¼ 7.5 Hz, 2H), 4.05 (t, J ¼ 7.5 Hz, 2H), 7.00 (d, J ¼ 8.9 Hz, 2H), 7.25 (t,
J ¼ 8.0 Hz,1H), 7.33 (t, J ¼ 8.0 Hz, 1H), 7.35 (d, J ¼ 8.0 Hz,1H), 7.61 (d,
Yield 56%; 1H NMR (CDCl3)
d
¼ 0.95 (t, J ¼ 7.6 Hz, 3H), 1.41 (sex,
J ¼ 7.6 Hz, 2H), 1.67 (quin, J ¼ 7.6 Hz, 2H), 2.17 (s, 3H), 2.65 (s, 3H),
3.12 (t, J ¼ 7.6 Hz, 2H), 3.86 (s, 2H), 6.56 (s, 1H), 7.23e7.30 (m, 3H),
7.54 (s, 1H), 7.59 (d, J ¼ 7.8 Hz, 1H); 13C NMR (CDCl3)
d
¼ 14.0, 17.1,
J ¼ 8.0 Hz, 1H), 7.90 (d, J ¼ 8.9 Hz, 2H); 13C NMR (CDCl3)
d
¼ 13.8,
17.3, 22.6, 31.2, 34.3, 115.6, 115.7, 118.1, 120.0, 126.3, 129.4, 130.2,
138.7, 141.7, 143.8, 147.6, 151.0; EIMS(70 eV) m/z (rel intensity) 281
(Mþ; 4), 135 (22), 134 (24), 120 (100); Anal. Found: C, 77.14; H, 8.37;
N, 15.14%. Calcd for C18H23N3: C, 76.83; H, 8.24; N, 14.93%.
14.0, 19.2, 22.5, 31.1, 31.2, 34.3, 68.0, 114.6 (2C), 115.2, 124.7 (2C),
126.4, 130.2, 130.4, 142.2, 147.3, 150.4, 161.5; EIMS (70 eV) m/z (rel
intensity) 310 (Mþ; 100), 164 (24); Anal. Found: C, 77.60; H, 8.49; N,
8.89%. Calcd for C20H26N2O: C, 77.38; H, 8.44; N, 9.02%.
2.6.4. 4-Amino-2’-butyl-3,5-dimethylazobenzene (22)
2.7.5. 2-Butyl-4’-octyloxyazobenzene (34)
Yield 49%; 1H NMR (CDCl3)
d
¼ 0.91 (t, J ¼ 7.6 Hz, 3H), 1.39 (sex,
Yield 95%; 1H NMR (CDCl3)
d
¼ 0.90 (t, J ¼ 7.4 Hz, 3H), 0.92 (t,
J ¼ 7.6 Hz, 2H), 1.65 (quin, J ¼ 7.6 Hz, 2H), 2.53 (s, 6H), 3.06 (t,
J ¼ 7.6 Hz, 2H), 3.82 (s, 2H), 6.41 (s, 2H), 7.21e7.31 (m, 3H), 7.58 (d,
J ¼ 7.7 Hz, 3H), 1.30e1.45 (m, 12H), 1.65 (quin, J ¼ 7.4 Hz, 2H), 1.81
(quin, J ¼ 7.7 Hz, 2H), 3.11 (t, J ¼ 7.4 Hz, 2H), 4.02 (t, J ¼ 7.7 Hz, 2H),
6.99 (d, J ¼ 8.7 Hz, 2H), 7.23e7.34 (m, 3H), 7.61 (d, J ¼ 7.8 Hz, 1H),
J ¼ 7.8 Hz,1H); 13C NMR (CDCl3)
¼ 14.0, 21.0, 22.9, 31.6, 34.2,114.9,
d
115.3 (2C), 126.3 (2C), 129.4, 130.3, 136.2, 141.8, 142.4, 147.5, 151.4;
EIMS(70 eV) m/z (rel intensity) 281 (Mþ; 9), 135 (31), 120 (100);
Anal. Found: C, 77.12; H, 8.34; N, 14.77%. Calcd for C18H23N3: C,
76.83; H, 8.24; N, 14.93%.
7.90 (d, J ¼ 8.7 Hz, 2H); 13C NMR (CDCl3)
d
¼ 14.0, 14.1, 22.5, 22.7,
26.0, 29.18, 29.24, 29.4, 31.1, 31.8, 34.3, 68.3, 114.6 (2C), 115.3, 124.7
(2C), 126.4, 130.2, 130.4, 142.3, 147.3, 150.4, 161.5; EIMS (70 eV) m/z
(rel intensity) 366 (Mþ; 60), 323 (29), 108 (100); Anal. Found: C,
78.96; H, 9.48; N, 7.65%. Calcd for C24H34N2O: C, 78.64; H, 9.35; N,
7.64%.
2.7. Synthesis of 4-[2-(butylphenylazo)]phenylene ethers 30e36
To an acetone solution (10 mL) of 2-butyl-4’-hydrox-
yazobenzene (29, 250 mg, 1.0 mmol) were added an alkyl iodide (F,
2.0 mmol) and potassium carbonate (280 mg, 2.0 mmol). The
mixture was refluxed for 24 h. After the reaction was completed,
the solvent was removed in vacuo. The resultant precipitate was
poured into water (20 mL). The product was extracted with ethyl
acetate (20 mL ꢂ 2) and purified by silica gel column chromatog-
raphy (AcOEt: C6H14 ¼ 1: 20).
2.7.6. 2-Butyl-4’-dodecyloxyazobenzene (35)
Yield 88%; 1H NMR (CDCl3)
d
¼ 0.88 (t, J ¼ 7.5 Hz, 3H), 0.92 (t,
J ¼ 7.4 Hz, 3H), 1.27e1.48 (m, 20H), 1.65 (quin, J ¼ 7.4 Hz, 2H), 1.81
(quin, J ¼ 7.5 Hz, 2H), 3.11 (t, J ¼ 7.4 Hz, 2H), 4.03 (t, J ¼ 7.5 Hz, 2H),
6.99 (d, J ¼ 9.2 Hz, 2H), 7.24e7.34 (m, 3H), 7.61 (d, J ¼ 8.2 Hz, 1H),
7.89 (d, J ¼ 9.2 Hz, 2H); 13C NMR (CDCl3)
d
¼ 14.0, 14.1, 22.5, 22.7,
26.0, 29.2, 29.35, 29.38, 29.58, 29.60, 29.64, 29.67, 31.1, 31.9, 34.3,
68.3, 114.7 (2C), 115.3, 124.7 (2C), 126.4, 130.2, 130.4, 142.2, 147.3,