and a UNICAM SP 1050 spectrometer as KBr discs unless
otherwise stated. UV–visible spectra were recorded on a
Phillips PV 8720 UV–vis scanning spectrophotometer with
absorption maxima reported in nm along with (log10 ε). Mass
spectra were obtained using a VG MASSLAB 12–250 quad-
rupole instrument using alternating chemical/electron impact
ionisation (ACE) conditions. Accurate masses were recorded on
a ZAB-E VG analytical reverse geometry magnetic instrument.
Elemental analyses were provided by the Microanalytical
Service at the University of Wales Cardiff. Molecular weight
determinations were carried out at the RARDE (MoD) estab-
lishment, Waltham Abbey using a Waters GPC system
equipped with Waters Expert Version 4.0 analytical software,
and are in polystyrene equivalents. The ultrasonic probe used
was a 100 W Ultrasonic Amplifier, type L665. Electrical con-
ductivities were determined by converting the dried powders to
discs of 1 cm diameter and 0.5 mm thickness. Slabs of these
discs, of known dimensions were cut and the ends coated with
colloidal silver. Two platinum wires were attached to the silver
and to a 10 point plug. The resistance was measured using a
Keithley 602 programmable electrometer.
0.25 (18H, s, Si-CH3). δC 0.44 (Si-CH3), 14.41 (CH3CH2), 23.11
(CH2CH3), 33.17 (Ar-CH2CH2-), 34.25 (Ar-CH2-CH2), 99.39
᎐
᎐
(-C᎐C-SiMe ), 104.48 (Ar-C᎐C-), 123.1 (C-1), 132.98 (C-3),
᎐
᎐
3
143.09 (C-2). m/z 382, 367, 351, 339, 310, 295, 280. Found, C,
75.25; H, 9.99%, Mϩ, 382.2512. C24H38Si2 requires C, 75.4; H,
9.9%, Mϩ, 382.2510.
1,4-Bis(3-hydroxy-3-methylbut-1-ynyl)-2,5-di-n-butylbenzene,
17. A mixture of 1,4-dibromo-2,5-di-n-butylbenzene 9 (9.0 g,
25.8 mmol), Pd(PPh3)2Cl2 (0.51 g, 0.73 mmol, 2.8 mol%), CuI
(0.15 g, 0.79 mmol), and 2-methylbut-3-yn-2-ol, 29 in Pri2NH
(200 ml) was stirred at 75 ЊC for 24 h. Removal of the solvent
was followed by chromatography on silica gel (500 g) using
petroleum ether (40–60 ЊC) and chloroform mixtures. The
product (6.7 g, 73%) was obtained as pale yellow needles, mp
130–132 ЊC. δH 7.19 (2H, s, H-3), 2.65 (4H, t, Ar-CH2), 2.35
(2H, s, OH), 1.62 (12H, s, CH3-C(OH)), 1.54 (4H, m, Ar-CH2-
CH2), 1.36 (4H, m, CH2-CH3), 0.93 (6H, t, CH2-CH3). δC 142.21
᎐
(C-2), 132.44 (C-3), 122.15 (C-1), 98.35 (Ar-C᎐C), 81.1 (Ar
᎐
᎐
C᎐C-), 65.87 (CMe ), 33.81 (ArCH ), 32.82 (Ar CH CH ),
᎐
2
2
2
2
22.7 (CH2CH3), 14.11 (CH3CH2). λmax 272 (4.45), 280.5 (4.48).
m/z, 354, 339, 297. Found, C, 81.42; H, 9.76%; Mϩ, 354.2559.
C24H34O2 requires C, 81.4; H, 9.6%; Mϩ, 354.2557.
Preparation of aryldiyne monomers
1,4-Bis(trimethylsilylethynyl)benzene, 12.
Trimethylsilyl-
1,4-Bis(3-hydroxy-3-methylbut-1-ynyl)-2,5-di-n-butoxy-
benzene, 19. A 500 ml round-bottomed flask was charged with
1,4-dibromo-2,5-di-n-butoxybenzene, 11 (15 g, 39.5 mmol),
Pd(PPh3)2Cl2 (0.4 g, 0.37 mmol, 1.4 mol%), CuI (0.19 g, 1
mmol), 29 (15 g, 179 mmol, 4.5 equiv.) and Pri2NH (250 ml). The
reaction mixture was stirred at 70 ЊC for 18 h, the solvent was
evaporated and the residue was purified on silica (500 g) using
CHCl3 as eluent. Brown needles (15 g) were obtained and on
crystallisation from acetone–water, and the product 19 (13.2 g,
88%) was isolated as fine white needles, mp 139–141 ЊC. δH 6.82
(2H, s, H-3), 3.92 (4H, t, OCH2), 2.90 (2H, s, HO-), 1.76 (4H,
m, OCH2CH2), 1.61 (12H, s, C(OH)-CH3), 1.51 (4H, m,
CH2CH3), 0.97 (6H, t, CH3CH2). δC 153.56 (C-2), 117.13 (C-3),
113.48 (C-1), 99.28 (C-4Ј), 78.37 (C-3Ј), 31.4 (O-CH2CH2 and
C-2Ј), 19.20 (CH2CH3), 13.85 (CH3-CH2). λmax 269.9 (4.73), 278
(4.87), 338 (4.11). m/z 386, 328. Found, C, 74.78; H, 9.08%; Mϩ,
386.2457. C24H34O4 requires C, 74.6; H, 8.8%; Mϩ, 386.2455.
ethyne 28 (7.7 g, 38.6 mmol) was added by syringe to a 500 ml
round-bottomed flask containing a well stirred mixture of 1,4-
dibromobenzene (9.1 g, 38.6 mmol), Pd(PPh3)2Cl2 (0.3 g, 0.43
mmol, 1.1 mol%), CuI (0.14 g, 0.74 mmol) and diisopropyl-
amine (150 ml). The resultant mixture was stirred at 70 ЊC
for 3.5 h. The solvent was removed and the grey–black residue
was placed on alumina (100 g) and eluted with petroleum spirit
(40–60 ЊC). Compound 12 (10 g, 96%) was obtained as white
crystals, mp 122 ЊC (lit.52 122 ЊC). δH 7.39 (4H, s), 0.24 (18H, s).
᎐
᎐
δC 104.5, 96.2 (C᎐CH), 131 (d, (Ar)CH), 123.1 ((Ar)C-C᎐C),
᎐
᎐
Ϫ0.21 (Si-CH3). λmax (CHCl3) 279.6 (3.59), 287.8 (3.44), 294.1
(3.67). νmax/cmϪ1 2150 (-C᎐C stretch). m/z 270, 255, 240,
᎐
᎐
225, 210, 195, 180. Found, Mϩ, 270.1260. C16H22Si2 requires
270.1259.
2,5-Bis(trimethylsilylethynyl)-1,4-dimethoxybenzene, 14.
A
mixture of 1,4-dimethoxy-2,5-dibromobenzene12 (15 g, 50.7
mmol), Pd(PPh3)2Cl2 (0.38 g, 0.54 mmol, 1.1 mol%), CuI (0.1 g,
0.53 mmol) and piperidine (150 ml) was well stirred in a 500 ml
round-bottomed flask. Trimethylsilylethyne 28 (10 g, 102
mmol) was added by syringe and the reaction mixture stirred at
70 ЊC for 6 h. The solvent was evaporated and 14 (12 g, 71%)
was obtained as pale yellow crystals, mp 162–163 ЊC, by elution
with light petroleum from alumina. δH 6.29 (2H, s, Ar-H),
3.83 (6H, s, OCH3), 0.27 (18H, s, Si(CH3)3). δC 0.12 (Si-CH3),
1,4-Diethynylbenzene, 20.52 Potassium carbonate (0.25 g, 1.85
mmol) was added to a 250 ml round-bottomed flask charged
with 12 (0.5 g, 1.85 mmol) and methanol (100 ml). The mixture
was stirred at room temperature for 16 h during which time the
K2CO3 dissolved. Water (200 ml) was added and the precipitate
was filtered and dried under reduced pressure at room temper-
ature. Product 20 was obtained as white crystals mp 95–96 ЊC
(lit.44 95–96 ЊC). δH 3.17 (2H, s, H-C᎐C), 7.44 (4H, s, Ar-H).
᎐
᎐
᎐
᎐
56.55 (OCH ), 100.5, 101.0 (C᎐C), 113.7 ((Ar)C-C᎐C), 116.4
᎐
᎐
᎐
᎐
3
δC 132.18 (C-2), 127.77 (C-1), 83.22 (Ar C᎐C), 79.21 (C᎐CH).
᎐
᎐
λmax (CHCl3) 262.3 (4.39), 275 (4.45). νmax/cmϪ1 3270 (C᎐C-H).
(Ar-CH), 154.35 (Ar, C-OCH3). λmax (CHCl3) 241.3 (3.19),
᎐
᎐
271.1 (3.40), 287.2 (3.67), 355.2 (3.17). νmax/cmϪ1 2140 (C᎐C
᎐
᎐
2,5-Diethynyl-1,4-dimethoxybenzene, 22.53 Compound 14 (4.5
g, 13.6 mmol) dissolved in MeOH (150 ml) was stirred with
K2CO3, (4 g, 29 mmol) for 12 h at room temperature. Water
(200 ml) was added and the product (2.2 g, 87%) was collected
stretch). m/z 330, 315, 300, 285, 270, 255, 240, 225. Found, C
65.46; H, 7.87%, Mϩ, 330.1471. C18H26O2Si2 requires C, 65.5;
H, 7.9%, Mϩ, 330.14698.
1,4-Bis(trimethylsilylethynyl)-2,5-di-n-butylbenzene, 13.
Piperidine (50 ml), 1,4-dibromo-2,5-di-n-butylbenzene 9 (3.1 g,
8.1 mmol), Pd(PPh3)2Cl2 (0.167 g, 0.24 mmol, 2.9 mol%) and
CuI (0.056 g, 0.29 mmol) were stirred in a 250 ml round-
bottomed flask. Trimethylsilylethyne 28 (1.8 g, 18.4 mmol) was
added and the reaction mixture was stirred at 70 ЊC for 30 h.
The solvent was removed and the residue was chromatographed
twice through alumina (2 × 200 g) using light petroleum
(40–60 ЊC) as eluent. Compound 13 was obtained as light brown
crystals which on crystallisation from ethanol–water gave 13
(0.19 g, 7%) as cream coloured needles, mp 53–55 ЊC. δH 7.24
(2H, s, Ar-H), 2.69 (4H, t, Ar-CH2-), 1.58 (4H, m, (Ar)
CH2CH2-), 1.37 (4H, m, CH2-CH3), 0.93 (6H, t, CH3-CH2-),
as white crystals, mp 163–166 ЊC (lit.53 153–154 ЊC). δH 6.97
᎐
(2H, s, C-1), 3.85 (6H, s, OCH ), 3.39 (2H, s, C᎐C-H). δ 154.47
᎐
3
C
᎐
(C-1), 116.27 (C-2), 112.75 (C-3), 82.12 (ArC᎐CH), 79.7
᎐
᎐
(-C᎐CH). λ
243.1 (3.89), 263.7 (4.18), 272.5 (4.22), 347.3
᎐
max
(3.95). νmax/cmϪ1 3260 (C᎐C-H stretch).
᎐
᎐
1,4-Diethynyl-2,5-di-n-butylbenzene, 21. Sodium hydride (2.5
g, 104 mmol) was added to a solution of 17 (10.5 g, 29.6 mmol)
in toluene (150 ml). The mixture was heated under reflux for
16 h then cooled and the supernatant liquid was decanted from
the solid in the bottom of the flask. The solvent was evaporated
leaving a viscous blood-red liquid which was placed on silica
(250 g) and eluted with petroleum spirit (30–40 ЊC). Product 21
2292
J. Chem. Soc., Perkin Trans. 1, 2000, 2289–2294