solvent. N gas was bubbled through the mixture at room
temp. and diethyl azodicarboxylate (0.020 mol) was added
(DMAP) in dry methylene chloride was treated with 4 mmol
(0.83 g) of dicyclohexylcarbodiimide (DCC) at 0 °C. The tem-
perature was allowed to rise to room temp. and stirring was
continued for 3 h. Urea was filtered off and the filtrate was
evaporated to dryness. Column chromatography on silica gel
with light petroleum–ethyl acetate (951) as eluent gave 1.0 g
of pure product (80%). [a] 22−28.7 (CHCl ). d (CDCl ) 0.89
(t, 3 H), 1.2–1.5 (m, 14 H), 1.6 (m, 2H), 1.69 (d, 3 H), 1.80
(quintet, 2 H), 2.02 (q, 2 H), 4.00 (t, 2 H), 4.15 (m, 2 H), 4.82
(q, 1 H), 4.95 (m, 2 H), 5.80 (m, 1 H), 6.98 (d, 2 H), 7.03 (d, 1
H), 7.38 (dd, 1 H), 7.58 (d, 2 H), 7.68 (d, 2 H), 7.78 (d, 1 H),
8.18 (d, 2 H).
2
during 30 min. After 3 h of additional stirring at room temp.
the solvent was evaporated from the reaction mixture. The
resulting solid was dissolved in ethyl acetate and on adding
four times the volume of light petroleum, triphenylphosphine
oxide was precipitated. The solution was evaporated to dryness
and the product recrystallized from light petroleum, 4.76 g
(83%). d (CDCl ) 1.26 (t, 3 H), 1.71 (d, 3 H), 4.23 (m, 2 H),
D
3
H
3
H
3
4.84 (q, 1 H), 7.05 (d, 1 H), 7.40 (dd, 1 H), 7.53 (t, 2 H), 7.67
(t, 1 H), 7.79 (d, 1 H), 8.18 (d, 2 H).
2-(2R)-(4-Hydroxy-2-nitrophenoxy)propanoic acid 10. To
0.008 mol (2.87 g) of 9 in ethanol (120 ml), 0.016 mol of
potassium hydroxide in a few millilitres of water was added.
The mixture was stirred overnight at room temp. Ethanol was
evaporated and the product was extracted from methylene
chloride with water. Water was evaporated and the solid was
dissolved in ethyl acetate. The insoluble part was filtered off
and the filtrate was evaporated to dryness and used without
further purification. d ([2H ] DMSO) 1.47 (d, 3 H), 4.89 (q,
4-[(1R)-1-Butoxycarbonylethoxy]-2-nitrophenyl 4∞-(undec-
10-enyloxy)biphenyl-4-carboxylate 13c. From 6a and 12c as for
13b. [a] 22+21.7 (CHCl ). d (CDCl ) 0.93 (t, 3 H), 1.24–1.43
(m, 12 H), 1.48 (m, 2 H), 1.64 (m, 2 H), 1.69 (d, 3 H), 1.82
(quintet, 2 H), 2.05 (q, 2 H), 4.02 (t, 2 H), 4.21 (t, 2 H), 4.82
(q, 1 H), 4.97 (m, 2 H), 5.82 (m, 1 H), 7.01 (d, 2 H), 7.23 (dd,
1 H), 7.30 (d, 1 H), 7.6 (d+d, 3 H), 7.70 (d, 2 H), 8.22 (d, 2 H).
D
3
H
3
H
6
1 H), 7.01 (dd, 1 H), 7.07 (d, 1 H), 7.19 (d, 1 H), 9.9 (s, 1 H).
4-[(1R)-Butoxycarbonylethoxy]phenyl-3∞-nitro-4∞-(undec-10-
enyloxy)biphenyl-4-carboxylate 13d. From 6b and 12a as for
13b. [a] 22+16.0 (CHCl ). d (CDCl ) 0.92 (t, 3 H), 1.2–1.55
2-(2R)-(4-Hydroxy-3-nitrophenoxy)propanoic acid 11. To a
D
3
H
3
solution
of
2-(2R)-(4-hydroxyphenoxy)propanoic
acid
(m, 16 H), 1.64 (d, 3 H), 1.88 (quintet, 2 H), 2.05 (q, 2 H), 4.17
(m, 4 H), 4.75 (q, 1 H), 4.97 (m, 2 H), 5.82 (m, 1 H), 6.94 (d, 2
H), 7.14 (d, 2 H), 7.18 (d, 1 H), 7.69 (d, 2 H), 7.80 (dd, 1 H),
8.13 (d, 1 H), 8.26 (d, 2 H).
(0.027 mol, 5.0 g) in acetic acid (100 ml) concentrated nitric
acid (1.5 ml) was added dropwise. The temperature of the
reaction mixture was kept below 35 °C. After 30 min the
reaction mixture was poured into water. The product was
extracted from the aqueous phase using diethyl ether. No
further purification was done. Yield 5.1 g (80%). d ([2H ]
Polymers 14a–d. Dry equipment was used. 0.26 g of poly(di-
methyl-co-methylhydrogen)siloxane (2.751) (corresponding to
1.0 mmol Si-H) and 1.1 mmol of 13a-d were dissolved in dry
toluene (2 ml). Catalyst solution [0.8 ml; dicyclopentadienyl-
platinum() chloride in dry toluene; 0.1 mg ml−1] was added
and the reaction flask was sealed with a septum and heated to
110 °C. After 2 d an additional 0.8 ml of catalyst solution was
added and heating was continued. The reaction was monitored
by IR spectroscopy and further addition of catalyst continued
until the SiMH signal at ca. 2155 cm−1 was constant relative
to the CNO signal at ca. 1740 cm−1. The reaction mixture
was added dropwise to methanol (400–800 ml) during vigorous
stirring. The product was collected by centrifugation.
Reprecipitation from chloroform in methanol was continued
until no free side-chain could be detected by thin layer chroma-
tography. Treatment of the product by dissolving it in ethyl
acetate and passing the solution through a 0.2 mm Teflon filter
often reduced the amount of remaining SiMH drastically. Yield
0.5–0.8 g. 1H NMR spectra of the polymers show broader
signals than those of the side chain precursors, but are other-
wise very similar except that the signals from methyl groups
attached to silicon at d 0–0.16 and a methylene group attached
to silicon at d 0.5 are present, while the olefinic protons at d
4.95–4.97 and d 5.80–5.82 are absent. A SiMH signal appeared
at d 4.7, equivalent to 10–15% unreacted hydrogens.
H
6
DMSO) 1.53 (d, 3 H), 4.89 (q, 1 H), 7.11 (d, 1 H), 7.24 (dd, 1
H), 7.39 (d, 1 H), 10.6 (s, 1 H).
Butyl 2-(2R)-(4-hydroxyphenoxy)propanoate 12a. A solution
of 2-(2R)-(4-hydroxyphenoxy)propanoic acid (0.01 mol, 1.9 g)
in butanol (150 ml) was treated with hydrogen chloride gas
until no further heat was evolved. The reaction mixture was
evaporated to dryness. The product was separated by column
chromatography on silica gel with light petroleum–ethyl acet-
ate (251) as eluent. Yield 1.6 g (64%). [a] 22+33.9 (CHCl ).
D
3
d
(CDCl ) 0.88 (t, 3 H), 1.30 (m, 2 H), 1.6 (d+m, 5 H), 4.14
H
3
(m, 2 H), 4.65 (q, 1 H), 6.72 (m, 4 H).
Esters 12b and c were synthesized as for 12a starting from
10 and 11 respectively.
Butyl 2-(2R)-(4-hydroxy-2-nitrophenoxy)propanoate 12b.
[a] 22−84 (CHCl ). d (CDCl ) 0.90 (t, 3 H), 1.31 (m, 2 H),
1.60 (m, 2 H), 1.66 (d, 3 H), 4.16 (m, 2 H), 4.74 (q, 1 H), 6.94
D
3
H
3
(d, 1 H), 6.97 (dd, 1 H), 7.32 (d, 1 H).
Butyl 2-(2R)-(4-hydroxy-3-nitrophenoxy)propanoate 12c.
[a] 22+77.1 (CHCl ). d (CDCl ) 0.92 (t, 3 H), 1.35 (m, 2 H),
D
3
H
3
1.64 (d+m, 5 H), 4.18 (m, 2 H), 4.73 (q, 1 H), 7.10 (d, 1 H),
7.27 (dd, 1 H), 7.48 (d, 1 H), 10.3 (s, 1 H).
14a [a] 22+13.8 (CHCl ).
The last reaction step to the mesogenic side-chain precursors
13a–d was similar for all and is described for 13b.
D
3
14b [a] 22−10.0 (CHCl ).
D
3
14c [a] 22+15.3 (CHCl ).
4-[(1R)-Butoxycarbonylethoxy]phenyl
enyloxy)biphenyl-4-carboxylate 13a. From 6a and 12a as for
4∞-(undec-10-
D
3
14d [a] 22+10.0 (CHCl ).
D
3
13b. [a] 22+18.0 (CHCl ). d (CDCl ) 0.90 (t, 3 H), 1.2–1.5
D
3
H
3
(m, 14 H), 1.6 (d+m, 5 H), 1.81 (quintet, 2 H), 2.04 (q, 2 H),
4.00 (t, 2 H), 4.17 (m, 2 H), 4.74 (q, 1 H), 4.97 (m, 2 H), 5.81
(m, 1 H), 6.92 (d, 2 H), 7.00 (d, 2 H), 7.13 (d, 2 H), 7.58 (d, 2
H), 7.68 (d, 2 H), 8.21 (d, 2 H).
Sample preparation and electric measurements
For the study of physical properties such as electro-optic effects
in smectic liquid crystals, the achievement of well aligned
samples is essential. Our standard shear cell,30 built for
measurements on low molar mass ferroelectric liquid crystals,
has proved very useful for obtaining aligned polymer samples
and was used for all polymeric liquid crystals and some low
4-[(1R)-Butoxycarbonylethoxy]-3-nitrophenyl 4∞-(undec-10-
enyloxy)biphenyl-4-carboxylate 13b. From 6a and 12b. Dry
glassware was used. A mixture of 2 mmol (0.73 g) of 12b,
2 mmol (0.57 g) of 6a and 15 mg of dimethylaminopyridine
356
J. Mater. Chem., 1998, 8(2), 353–362