Halogen-containing heterocyclic compound and liquid crystal composition

A novel liquid crystalline, halogen-containing heterocyclic compound having a characteristic that even when its S.sub.c * phase is supercooled, no other smectic phases appear, and a liquid crystal composition containing the same are provided, which compound is expressed by the formula ##STR1## wherein R.sub.1 and R.sub.2 each represent an alkyl group of 2 to 18 carbon atoms; X represents --N.dbd. or --CH.dbd.; Y represents F or Cl; n represents an integer of 0 to 10; and a symbol * represents an asymmetric carbon atom.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a novel liquid crystalline substance and a liquid 
crystal composition containing the same. More particularly it relates to a 
liquid crystalline substance containing an optically active group and a 
racemate thereof and further a chiral liquid crystal composition 
containing these. 
The liquid crystalline substance referred to in the present invention 
includes not only compounds the liquid crystalline state of which can be 
observed by themselves, but also substances the liquid crystalline state 
of which cannot be observed by themselves, but which nevertheless have a 
chemical structure similar to that of the former compounds and are useful 
as a component constituting liquid crystal compositions. 
2. Description of the Related Art 
Twisted nematic (TN) type display mode has currently been most widely 
employed as liquid crystal display elements, but it is inferior in the 
response rate as compared with emissive type display elements such as 
electroluminescence, plasma display, etc., and various attempts for 
overcoming this drawback have been made, but, nevertheless, it seems that 
a possibility of improvement to a large extent has not been achieved. 
Thus, various liquid crystal display equipments based on different 
principles in place of TN type display elements have been attempted, and 
as one of them, there is a display mode utilizing ferroelectric liquid 
crystals (N. A. Clark and S. T. Layerwall, Applied Phys. Lett., 36,899 
(1980)). This mode utilizes the chiral smectic C phase (hereinafter 
abbreviated to SC* phase) or chiral smectic H phase (hereinafter 
abbreviated to SH-phase) of ferroelectric liquid crystals, and these 
phases are preferred to be in the vicinity of room temperature. The 
present inventors have made various searches for liquid crystal substances 
containing an optically active group, mainly in order to develop liquid 
crystal substances suitable for being used for the above display mode, and 
as a result have attained the present invention. 
SUMMARY OF THE INVENTION 
The present inventors have searched for various liquid crystal substances 
having an optically active group mainly in order to develop liquid crystal 
substances suitable to be utilized for the abovementioned mode and have 
achieved the present invention. 
The present invention resides in a liquid crystalline, optically active, 
halogen-containing heterocyclic compound expressed by the formula 
##STR2## 
wherein R.sub.1 and R.sub.2 each represent an alkyl group of 2 to 18 
carbon atoms; X represents --N.dbd. or --CH.dbd.; Y represents F or Cl; n 
represents an integer of 0 to 10; and the symbol * represents an 
asymmetric carbon atom, and its racemates and further a chiral smectic 
liquid crystal composition containing at least one memeber thereof. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Compounds of the formula (I) wherein X is --N.dbd. i.e. expressed by the 
formula 
##STR3## 
wherein R.sub.1, R.sub.2, Y, n and * are as defined above, are 
2-aryl-substituted-5-alkylpyrimidines. 
Compounds of the formula (I) wherein X is --CH.dbd. i.e. expressed by the 
formula 
##STR4## 
wherein R.sub.1, R.sub.2, Y, n and * are as defined above, are 
2-aryl-substituted-5-alkylpyridines. 
The phase transition points of representative examples of the compounds 
expressed by the formula (Ia) and those expressed by the formula (Ib) are 
shown in Table 1 and Table 2. 
TABLE 1 
__________________________________________________________________________ 
Stereo- 
chemical 
Sample 
In formula (I) 
configu- 
Phase transition point (.degree.C.) 
No. R.sub.1 
R.sub.2 
Y n ration 
C S.sub.c * 
S.sub.A 
Ch I 
__________________________________________________________________________ 
a1 C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
F 2 S . 17.8 
-- -- -- . 
a2 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 2 S . 39.2 
-- -- -- . 
a3 C.sub.2 H.sub.5 
C.sub.9 H.sub.19 
F 2 S . 42.2 
-- -- -- . 
a4 C.sub.2 H.sub.5 
C.sub.12 H.sub.25 
F 1 S . 39.2 
-- (. 37.3) 
-- . 
a5 C.sub.2 H.sub.5 
C.sub.12 H.sub.25 
F 2 S . 37.5 
-- (. 36.4) 
-- . 
a6 C.sub.2 H.sub.5 
C.sub.6 H.sub.13 
F 3 S . 21.0 
(. 19.0) 
. 27.0 
-- . 
a7 C.sub. 2 H.sub.5 
C.sub.7 H.sub.15 
F 3 S . 39.5 
(. 28.1) 
. 41.7 
-- . 
a8 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 3 S . 35.2 
. 36.9 
. 41.0 
-- . 
a9 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 3 racemic 
. 36.5 
. 37.3 
. 41.8 
-- . 
a10 C.sub.2 H.sub.5 
C.sub.9 H.sub.19 
F 3 S . 40.4 
. 44.4 
. 47.1 
-- . 
a11 C.sub.2 H.sub.5 
C.sub.12 H.sub.25 
F 3 S . 37.9 
. 49.0 
. 49.2 
-- . 
a12 C.sub.2 H.sub.5 
C.sub.7 H.sub.15 
F 4 S . 30.0 
-- . 38.7 
-- . 
a13 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 4 S . 39.2 
(. 30.6) 
(. 38.6) 
-- . 
a14 C.sub.2 H.sub.5 
C.sub.9 H.sub.19 
F 4 S . 36.0 
. 37.5 
. 44.5 
-- . 
a15 C.sub.2 H.sub.5 
C.sub.12 H.sub.25 
F 4 S . 37.1 
. 47.3 
-- -- . 
a16 C.sub.2 H.sub.5 
C.sub.3 H.sub.7 
F 5 S . 46.0 
-- -- -- . 
a17 C.sub.2 H.sub.5 
C.sub.4 H.sub.9 
F 5 S . 27.4 
-- -- -- . 
a18 C.sub.2 H.sub.5 
C.sub.5 H.sub.11 
F 5 S . 59.0 
-- -- (. 25.7) 
. 
a19 C.sub.2 H.sub.5 
C.sub.6 H.sub.13 
F 5 S . 28.9 
(. 16.8) 
(. 26.0) 
(. 27.5) 
. 
a20 C.sub.2 H.sub.5 
C.sub.7 H.sub.15 
F 5 S . 29.2 
(. 23.0) 
. 42.1 
-- . 
a21 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 5 S . 10.0 
. 33.2 
. 43.0 
-- . 
a22 C.sub.2 H.sub.5 
C.sub.9 H.sub.19 
F 5 S . 26.0 
. 42.3 
. 51.0 
-- . 
a23 C.sub.2 H.sub.5 
C.sub.12 H.sub.25 
F 5 S . 46.0 
. 53.1 
-- -- . 
a24 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 6 S . 2.0 
. 24.3 
. 42.3 
-- . 
a25 C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
F 7 S . 27.4 
-- -- -- . 
a26 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 7 S . 16.0 
. 34.8 
. 45.2 
-- . 
a27 C.sub.6 H.sub.13 
C.sub.8 H.sub.17 
F 0 S . 0.0 
-- -- -- . 
a28 C.sub.8 H.sub.17 
C.sub.8 H.sub.17 
F 1 S . 31.0 
-- -- -- . 
a29 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
Cl 
5 S . 37.8 
-- -- -- . 
__________________________________________________________________________ 
TABLE 2 
______________________________________ 
Stereo- 
Sam- chemical Phase transition 
ple In formula (I) configu- point (.degree.C.) 
No. R.sub.1 R.sub.2 Y n ration C S.sub.c * 
S.sub.A 
I 
______________________________________ 
b1 C.sub.2 H.sub.5 
C.sub.6 H.sub.13 
F 4 S . 16.5 
. 21.5 
. 26.3 
. 
b2 C.sub.2 H.sub.5 
C.sub.6 H.sub.13 
F 5 S . 7.0 
. 30.8 
. 32.8 
. 
b3 C.sub.2 H.sub.5 
C.sub.7 H.sub.15 
F 3 S . 21.0 
. 35.1 
. 40.4 
. 
b4 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 3 S . 37.3 
. 39.8 
. 42.1 
. 
b5 C.sub.2 H.sub.5 
C.sub.8 H.sub.17 
F 4 S . 33.0 
. 33.5 
. 39.4 
. 
b6 C.sub.2 H.sub.5 
C.sub.9 H.sub.19 
F 4 S . 22.7 
. 51.0 
. 54.5 
. 
b7 C.sub.2 H.sub.5 
C.sub.10 H.sub.21 
F 1 S . 24.0 
-- . 32.3 
. 
b8 C.sub.2 H.sub. 5 
C.sub.10 H.sub.21 
F 3 S . 38.0 
. 42.8 
. 45.4 
. 
b9 C.sub.6 H.sub.13 
C.sub.7 H.sub.15 
F 0 R liquid at room 
temperature 
b10 C.sub.2 H.sub.5 
C.sub.4 H.sub.17 
F 5 S . 21.5 
. 43.2 
. 45.8 
. 
b11 C.sub.2 H.sub.5 
C.sub.9 H.sub.19 
F 7 S . 24.0 
. 50.0 
. 54.0 
. 
______________________________________ 
As seen from Table 1 and Table 2, most of the optically active substances 
among the compounds of the formula (I) of the present invention exhibit 
S.sub.c * phase at relatively low temperatures and within a broad 
temperature range in the vicinity of room temperature; hence they are very 
useful compounds for constituting liquid crystal compositions suitable to 
be used for light-switching mode utilizing ferroelectric properties. 
Further, the racemates among the compounds of the formula (I) exhibit 
S.sub.c phase in place of S.sub.c * phase, but their phase transition 
points are almost the same as those of the corresponding optically active 
substances, and if necessary by blending the racemates with the optically 
active substances, it is possible to utilize them for adjusting the 
helical pitch or cholesteric pitch of S.sub.c * phase or for other 
purposes. 
Further, the compounds of the formula (I) have a superior compatibility 
with other compounds exhibiting S.sub.c * phase or S.sub.H * phase, 
compounds exhibiting cholesteric phase, etc.; hence admixture of the 
compounds of the formula (I) with such other compounds is very effective 
for extending the temperature range in which S.sub.c * phase is exhibited, 
particularly the lower temperature range. 
Another specific feature of the compounds of the present invention consists 
in that the halogen atom is present as a substituent on the lateral side. 
It is at present very difficult to anticipate in what manner the change of 
the phase transition points due to replacement of hydrogen atom of the 
unsubstituted compound by the halogen atom or the like achieves in 
specified liquid crystal compounds. In general, there is a tendency that 
the upper limit temperature of liquid crystal phases, i.e., the clearing 
point thereof is reduced, but the extent of the reduction cannot be 
anticipated so that it is unclarified until a specified compound is 
practically prepared and its properties are measured. This applies even to 
the case of relatively simple liquid crystal phases such as nematic phase, 
and it applies much more to the case of smectic liquid crystals mainly 
aimed at in the present invention since various smectic modification are 
present in that case. 
Noting such point, the present inventors have made research on compounds 
containing a halogen atom on the lateral side thereof and as a result have 
achieved the present invention. Hereinafter, concretely, comparative data 
relative to the case where a halogen atom is introduced on the lateral 
side and the case where no halogen atom is introduced thereon will be 
illustrated and also the effectiveness will be mentioned. (a) Case of 
pyrimidine compounds of the formula (Ia): 
The comparisons of the phase transition points of compounds of the formula 
(Ia) of the present invention with those of the corresponding compounds 
having no substituent (X corresponds to hydrogen atom H) are exemplified 
in Table 3. 
TABLE 3 
______________________________________ 
Phase transition points (.degree.C.) 
Sample No. 
C S.sub.x S.sub.c * 
S.sub.A 
Ch I 
______________________________________ 
a8 . 35.2 -- . 36.9 
. 41.0 
-- . 
unfluorinated*.sup.1 
. 31.2 (. 16.8/S.sub.B) 
. 46.8 
. 50.8 
-- . 
a10 . 40.4 -- . 44.4 
. 47.1 
-- . 
unfluorinated*.sup.1 
. 23.0 . 28.0 . 30.0 
. 51.5 
. 52.0 
. 
a11 . 37.9 -- . 49.0 
. 49.2 
-- . 
unfluorinated*.sup.1 
. 41.0 (. 23.8) . 62.2 
-- -- . 
a15 . 37.1 . . 47.3 
-- -- . 
unfluorinated*.sup.1 
. 23 (. 16) . 61.5 
-- -- . 
a21 . 10.0 -- . 33.2 
. 43.0 
-- . 
unfluorinated*.sup. 
. 3.0 (. 14.2/S.sub.B) 
. 48.6 
. 56.3 
-- . 
______________________________________ 
*.sup.1 Data from Japanese patent application laidopen No.Sho61 93170 
As apparent from teh above comparative data, although the upper limit of 
temperature of S.sub.c * phase is liable to lower to some extent by the 
incorporation of halogen atom as in the formula (Ia) compounds of the 
present invention, a surprising effectiveness is obtained that appearances 
of other undesirable smectic phases (more highly ordered smectic 
modifications) at lower temperatures are surpressed. Actually, in the case 
of compounds of sample No. a21, no other smectic phases appear even if 
they are supercooled down to -13.degree. C., for example. At this point 
they are crystallized and the behavior at a lower temperature than 
-13.degree. C. could not be observed. (b) Case of pyridine compounds (1b): 
Examples in comparison of the phase transition points of compounds of the 
present invention in Table 2 with those of compounds having no F 
substituent on the lateral side i.e. compounds of Y=H in the formula are 
shown in Table 4. 
TABLE 4 
______________________________________ 
Phase transition points (.degree.C.) 
Sample No. 
C S.sub.H * 
S.sub.G * 
S.sub.F * 
S.sub.c * 
S.sub.A 
I 
______________________________________ 
b2 . 7.0 -- -- -- . 30.8 
. 32.8 
. 
Unfluorinated 
. 45.2 (. 44.2) 
. 48.5 
. 53.8 
. 63.0 
-- . 
b4 . 37.3 -- -- -- . 39.8 
. 42.1 
. 
Unfluorinated 
. 30.5 -- . 34.8 
. 51.0 
. 62.7 
-- . 
b5 . 33.0 -- -- -- . 33.5 
. 39.4 
. 
Unfluorinated 
. 21.5 -- (. 9.7) 
. 38.5 
. 59.1 
-- . 
b6 . 22.7 -- -- -- . 51.0 
. 54.5 
. 
Unfluorinated 
. 33.5 -- -- . 45.4 
. 63.0 
-- . 
b8 . 38.0 -- -- -- . 42.8 
45.4 
. 
Unfluorinated 
. 35.5 -- -- . 53.0 
. 64.0 
-- . 
______________________________________ 
The of unfluorinated compounds listed in Table 4 for comparison are 
disclosed in the prior patent application previously filed by the present 
inventors (Japanese patent application No. Sho 60-293934/1985), and in any 
case of the compounds, S.sub.F * phase, S.sub.G * phase, etc. appear at 
temperatures lower than those of S.sub.G * phase, whereas in the case of 
compounds of the formula (Ib) of the present invention, S.sub.c * phase 
remains as it is, down to -15.degree. C. in a supercooled state and other 
smectic phases as above are not observed. Thus it can been seen that 
introduction of a halogen atom on the lateral side has an effectiveness of 
notably inhibiting the appearance of smectic phases other than S.sub.c * 
phase at temperatures lower than that of S.sub.c * phase. 
Here, the difference between the prior art particularly related to 
compounds of the formula (Ia) among those of the present invention, that 
is, Japanese patent application laid-open No. Sho 59-210070/1984 (DE 
Patent No. 3315295.0) and the present invention will be described. 
In the prior art, Japanese patent application laidopen No. Sho 
59-210070/1984, a large number of arylpyridines having a fluorine 
substituent in the aryl group are claimed. In the prior art, compounds of 
90 general formulas are disclosed and about 196 compounds are enumerated. 
However, compounds the phase transition points of which are concretely 
shown are only the following 5 compounds: 
##STR5## 
The prior art describes that these compounds have a superior specific 
feature that addition thereof to other liquid crystals notably inhibits a 
smectic phaseforming tendency which is undesirable for liquid crystal 
compositions for display elements using nematic phase. 
The compounds of the formula (Ia) of the present invention may be possibly 
included in the claimed compounds in the prior art in a broad sense, but 
the compounds of the formula (Ia) themselves exhibit smectic phase. A 
compound most related to the compounds of the formula (Ia) among the 
above-mentioned five compounds is, of course, 
##STR6## 
However, this compound has a linear chain alkoxy group unlike the 
compounds of the formula (Ia) of the present invention, and according to 
the description of the prior art, it exhibits only a nematic phase; hence 
it has nothing to do with the chiral smectic compounds mainly aimed at in 
the present invention. In addition, the prior art discloses in an 
extremely general expression that the alkyl group may be a branched chain, 
optically active group, but no compounds having a branched chain alkyl 
group are found even among the above-mentioned 196 compounds, not to 
mention Examples. 
When chiral smectic liquid crystal compositions are composed using the 
compounds of the formula (I), it is possible to form them from a plurality 
of compounds of the formula (I), alone, and it is also possible to prepare 
liquid crystalline compositions exhibiting S.sub.c * phase, by mixing 
compounds of the formula (I) with other smectic liquid crystals. 
When the light switching effect of the S.sub.c * phase is applied to 
display elements, the resulting display elements have the following three 
superior specific features: 
The first specific feature is that the elements reply at a very high rate 
and the response times are 1/100 or less of those of display elements 
according to the usual TN display mode. 
The second specific feature is that the elements have a memory effect; 
hence multiplex drive is easy in combination of this effect with the 
above-mentioned high rate response properties. 
The third specific feature is that gray scale in TN display mode is 
attained by controlling the impressed voltage applied to display elements, 
but this is accompanied with difficult problems of the temperature 
dependency of threshold voltage value and the voltage dependency of 
response rate. However, in the case where the light switching effect of 
S.sub.c * phase is applied to the display elements, it is possible to 
easily attain the gray scale by controlling the switching time of 
polarity; hence the display elements are very suitable for graphic 
display. 
As for the display modes, the following two modes may be considered: 
one mode is of birefringence type using two pieces of polarizers and 
another is of guest-host type using dichroic dyestuffs. Since S.sub.c * 
phase has a spontaneous polarization, molecules reverse around the helical 
axis thereof as a revolving axis by reversing the polarity of impressed 
voltage. A liquid crystal composition having S.sub.c * phase is filled 
into a liquid crystal display cell subjected to an aligning treatment so 
that liquid crystal molecules can align in parallel to the surface of 
electrodes, followed by placing the liquid crystal cell between two pieces 
of polarizers arranged so that the director of the liquid crystal 
molecules can be in parallel to the polarization plane on another side, 
impressing a voltage and reversing the polarity to be thereby able to 
obtain a bright field and a dark field (determined by the opposed angles 
of polarizers). On the other hand, in the case where display elements are 
operated in guest-host mode, it is possible to obtain bright field and 
colored field (determined by the arrangement of polarization sheets) by 
reversing the polarity of impressed voltage. In general, it is difficult 
to align liquid crystal molecules in smectic state in parallel to the wall 
surface of glass; hence liquid crystal molecules have been aligned by 
cooling them very slowly (e.g. 1.degree..about.2.degree. C./hr) initially 
starting from their isotropic liquid, in a magnetic field of several tens 
Kilogauss or more, but in the case of liquid crystal substances having 
cholesteric phase, the substances are cooled at a cooling rate of 
1.degree. C./min. under impression of a direct current voltage of 50 to 
100V in place of magnetic field, whereby it is possible to easily obtain a 
monodomain state where liquid crystal molecules are uniformly aligned. 
Compounds of the formula (I) also have an optically active carbon atom; 
hence when they are added to nematic liquid crystals, they have a 
performance of having a twisted structure induced in the mixtures. Nematic 
liquid crystals having a twisted structure, i.e. chiral nematic liquid 
crystals, do not form the so-called reverse domain of TN type display 
elements; hence it is possible to use the compounds of the formula (I) as 
an agent for preventing the reverse domain. 
Next, preparation of the compounds of the formula (I) of the present 
invention will be described. Firstly, compounds of the formula (I) wherein 
X represents --N.dbd., i.e. compounds of the formula (Ia), may be most 
suitably prepared through the following passageway 1 or 2: (Passageway 1) 
##STR7## 
The succeeding steps are the same as those in the passageway 1. 
In the case of compounds of m=9 or more, in the above pasageways, 
passageway 2 is commercially more suitable than passageway 1, because 
N,N-dimethylaminoalkylacroleins (g) of m=9 or more used in the passageway 
1 are not suitable to mass production. 
Next, compounds of the formula (I) wherein X is --CH.dbd. i.e. compounds of 
the formula (Ib) may be most suitably prepared through the following 
preparation passageway: 
##STR8## 
In addition, in either of (Ia) or (Ib), when an optically active compound 
is used as 
##STR9## 
to be reacted at the final step, the final product is also optically 
active, while when a racemate is used, the final product is racemic. 
The compounds and liquid crystal composition of the present invention will 
be described in more detail by way of Examples.

EXAMPLE 1 
Preparation of (S)-2(p-6-methyl-octyloxy-m-fluorophenyl)-5-octyl-pyrimidine 
(a compound of the formula (Ia) wherein R.sub.1 =C.sub.2 H.sub.5, R.sub.2 
=n--C.sub.8 H.sub.17, X=--N.dbd., Y=F and n=5; sample No. a21) 
(i) Preparation of 2-(p-hydroxy-m-fluorophenyl)-5-octylpyrimidine ((i); 
Y=F). 
o-Fluoro-p-cyanoanisole as a known substance (m.p. 
98.5.degree.-99.5.degree. C., (d); Y=F) was reacted with anhydrous ethanol 
and hydrogen chloride in toluene to obtain an iminoether hydrogen chloride 
salt ((e); Y=F), which was then reacted with ammonia gas without its 
isolation, followed by removing ammonium chloride by filtration and 
thereafter distilling off the solvent to obtain an amidine hydrogen 
chloride salt ((f); Y=F), which was heated without particular 
purification, with an equivalent quantity of 
N,N-dimethylamino-octyl-acrolein ((g); m=8) in the presence of an alkali 
to obtain 2-(p-methoxy-m-fluorophenyl)-5-octyl-pyrimidine ((h); Y=F, m=8, 
m.p. 58.7.degree.-59.0.degree. C.). The above-mentioned process is a known 
chemical method in the case of an unsubstituted compound where of Y=H. 
This 2-(p-methoxy-m-fluorophenyl)-5-octylpyrimidine (50 g) was heated for 
substitution together with glacial acetic acid (500 ml) and hydrobromic 
acid (47%) (170 g) for 72 hours, followed by distilling off acetic acid 
and hydrobromic acid under reduced pressure, adding aqueous NaOH and 
toluene, extracting the objective substance into the toluene layer and 
then distilling off toluene to obtain 
2-(p-hydroxy-m-fluorophenyl)-5-octylpyrimidine ((i); Y=F, m=8) (48.5 g). 
This product was used in the next stage without its purification. 
(ii) Preparation of the captioned compound 
Compound (I) (Y=F, m=8) (5.0 g) obtained in the paragraph (i) was dissolved 
in an ethanol solution containing KOH (1.3 g), followed by adding 
(S)-6-methyloctyl-bromide (46 g), heating the mixture under reflux for 5 
hours, distilling off ethanol under reduced pressure, extracting the 
resulting product with ether, washing the ether layer with water, 
distilling off ether and recrystallizing the residue from ethanol to 
obtain the objective captioned compound (3.4 g). This product had the 
following phase transition points: 
C-S.sub.c * point: 10.0.degree. C., S.sub.c *-S.sub.A point: 33.2.degree. 
C., and 
S.sub.A -I point: 43.0.degree. C. Further, the S.sub.c * phase was cooled 
to examine whether another smectic phase is present or not. As a result, 
supercooling down to -13.degree. C. was possible while S.sub.c * phase was 
kept as it was, and the product crystallized without any appearance of 
another smectic phase. 
Further, the elemental analysis values thereof accorded well with its 
calculated values as follows: 
______________________________________ 
Analytical 
Calculated values 
values (%) 
(in terms of C.sub.27 H.sub.41 FN.sub.2 O) 
______________________________________ 
C 75.6 75.65 
H 9.8 9.44 
N 6.5 6.54 
F 4.4 4.43 
______________________________________ 
In the same manner as the above, it is possible to prepare other compounds 
of the formula (Ia) wherein the carbon number of R.sub.2 is 8 or less. 
Representative examples of such other compounds are shown in Table 1. 
In addition, in the above second stage (ii), it is possible to use a 
branched alkyl tosylate in place of the branched alkyl bromide. However, 
in the preparation of compounds which are optically active and wherein 
n=0, it is preferred to use a branched alkyl tosylate, not the branched 
alkyl bromide. The reason is that when an optically active alkyl bromide, 
##STR10## 
is prepared from the corresponding optically active, secondary alcohol, 
##STR11## 
reduction in the optical purity is difficultly avoidable. Whereas, in the 
case of preparation of an optically active tosylate, no reduction in the 
optical purity occurs. 
EXAMPLE 2 
Preparation of 
(S)-2(p-5-methyl-heptyloxy-m-fluorophenyl)-5-nonyl-pyrimidine (a compound 
of the formula (Ia) wherein R.sub.1 =C.sub.2 H.sub.5, R.sub.2 =n--C.sub.9 
H.sub.19, Y=F and n=4; sample No. a14) 
p-Methoxy-m-fluorobenzamidine hydrogen chloride salt ((f); Y=F) (40.9 g, 
0.2 mol) and n-nonyl diethylmalonate (b.p. 153.degree./5 mmHg) (57.3 g, 
0.2 mol) were heated under reflux with stirring in the presence of sodium 
ethoxide (0.66 mol) dissolved in ethanol (550 ml) for 6 hours, followed by 
acidifying the resulting material with dilute hydrochloric acid to obtain 
light yellow solids (64 g, m.p. 271.degree.-274.degree. C.) ((j); Y=F, 
m=9). 
This substance (64 g) was heated under reflux together with phosphorus 
oxychloride (POCl.sub.3) (385 ml) in the presence of N,N-diethylaniline 
(40 ml) for 19 hours, followed by distilling off excess POCl.sub.3, 
pouring the residue into ice and recrystallizing the resulting solids from 
pentane to obtain 
2-(p-methoxy-m-fluorophenyl)-4,6-dichloro-5-nonyl-pyrimidine ((k); Y=F, 
m=9) (m.p. 59.degree.-60.degree. C.) (35.8 g). 
This dichloro compound (35.7 g) was hydrogenated under the atmospheric 
pressure in the presence of Pd on carbon catalyst in the presence of 
triethylamine (34 g) in ethanol, followed by recrystallizing the resulting 
product from ethanol to obtain 
(S)-2-(p-methoxy-m-fluorophenyl)-5-nonyl-pyrimidine ((h); Y=F, m=9) (m.p. 
55.degree.-56.degree. C.) (23.4 g). 
This product was demethylated with hydrobromic acid/glacial acetic acid in 
the same manner as in Example 1, to obtain 
2-(p-hydroxy-m-fluorophenyl)-5-nonyl-pyrimidine ((i); Y=F, m=9) (m.p. 
46.degree.-47.5.degree. C.) (recrystallized from n-heptane). 
Etherification of the above compound of (i) (Y=F, m=9) with 
(S)-5-methyl-heptyl bromide was carried out in the same manner as in the 
step (ii) of Example 1. The resulting captioned compound had the following 
phase transition points: 
C-S.sub.c *: 36.degree. C., S.sub.c *-SA 37.5.degree. C., SA-I: 
44.5.degree. C. 
In the same manner as the above, it is possible to prepare any of the other 
compounds of the formula (Ia) wherein R.sub.2 =n-C.sub.9 H.sub.19 or 
longer chain. 
EXAMPLE 3 
Preparation of (S)-2-(p-5-methyl-heptyloxy-m-fluorophenyl)-5-octyl-pyridine 
(a compound of the formula (Ib) wherein R.sub.1 =C.sub.2 H.sub.5, R.sub.2 
=n-C.sub.8 H.sub.17, Y=F, and n=4; sample No. b5) 
Sodium methoxide (10.6 g, 0.196 mol) and toluene (600 ml) were agitated at 
room temperature, followed by dropwise adding to the mixture, a solution 
of m-fluoro-p-methoxyacetophenone as a known compound (30 g, 0.178 mol), 
ethyl formate (13.2 g, 0.178 mol) and toluene (200 ml), keeping the 
mixture at room temperature for 8 hours with stirring, adding water (500 
ml), transferring the resulting mixture into a separating funnel (the 
material corresponding to an aqueous solution of compound ((l); Y=F), 
adding to the aqueous solution, an aqueous solution of conc. sulfuric acid 
(6 ml) and water (180 ml), dissolving deposited crystals ((m); Y=F) in 
fresh toluene, drying the toluene solution of the compound (m) with 
calcium chloride, slowly dropwise adding thionyl chloride (40 ml) under 
cooling, heating the mixture under reflux for one hour, distilling off the 
solvent and excess thionyl chloride under reduced pressure, and 
recrystallizing the residue from heptane to obtain 
m-fluoro-p-methoxyphenyl-8-chlorovinyl ketone ((n); Y=F) (18.5 g). 
N-decenylpiperidine ((o); R.sub.2 =C.sub.8 H.sub.17) (b.p. 
117.degree.-118.degree. C. (2.5 mmHg)) (20.8 g, 0.093 mol) and 
triethylamine (9.4 g, 0.093 mol) were dissolved in ethyl ether (100 ml) 
with stirring, followed by dropwise adding to the solution, a solution of 
m-fluoro-p-methoxyphenyl-8-chlorovinyl ketone (18.5 g, 0.093 mol) obtained 
above and ethyl ether (250 ml), agitating the mixture at room temperature 
for 8 hours, adding water (50 ml) and toluene (30 ml), transferring the 
mixture into a separating funnel, twice washing the organic layer with 
water, distilling off the solvent from the organic layer under reduced 
pressure, adding to the resulting residue ((p); Y=F, R.sub.2 =C.sub.8 
H.sub.17), perchloric acid (70%) (36 ml), thereafter adding water (36 ml), 
heating the mixture under reflux for 10 minutes, cooling, washing the 
resulting crystals with ethyl ether, and drying the crystals to obtain 
2-(m-fluoro-p-methoxyphenyl)-5-octyl-pyrilium perchlorate ((q); Y=F, 
R.sub.2 =C.sub. 8 H.sub.17) (21.3 g). N-decenylpiperidine as its raw 
material was prepared from n-caprinaldehyde and piperidine according to 
the method of Mannich et al (Chem. Ber. 69, 2106 (1936)). 
This 2-(m-fluoro-p-methoxyphenyl)-5-octylpyrilium perchlorate (21.3 g, 
0.051 mol) was heated under reflux with stirring together with ammonium 
acetate (39.3 g, 0.510 mol) and acetic acid (500 ml) for 4 hours, followed 
by pouring the reaction fluid in water, dissolving the resulting crystals 
in toluene, transferring the solution into a separating funnel, three 
times washing it with water, distilling off the solvent under reduced 
pressure and recrystallizing the residue to obtain 
2-(m-fluoro-p-methoxyphenyl)-5-octyl-pyridine ((r); Y=F, R.sub.2 =C.sub.8 
H.sub.17) (10.3 g). This product had a m.p. of 41.0.degree.-48.3.degree. 
C. To this 2-(m-fluoro-p-methoxyphenyl)-5-pyridine (10.3 g, 0.033 mol) 
were added hydrobromic acid (47%) (50 ml) and acetic acid (140 ml), 
followed by heating the mixture under reflux for 30 hours, cooling, 
pouring it in water, filtering off the resulting crystals, dissolving the 
crystals in 2N NaOH aqueous solution, adding acetic acid to make the 
solution acidic, filtering off crystals and recrystallizing to obtain 
2-(m-fluoro-p-hydroxyphenyl)-5-octyl-pyridine ((s); Y=F, R.sub.2 =C.sub.8 
H.sub.17) (7 g). This product had a m.p. of 73.5.degree.-74.6.degree. C. 
To this 2-(m-fluoro-p-hydroxyphenyl)-5-octylpyridine (2 g, 0.007 mol) were 
added ethanol (20 ml), KOH (0.4 g, 0.007 mol) and optically active 
5-methylheptyl bromide (1.4 g, 0.007 mol), followed by heating the mixture 
under reflux with stirring for 4 hours, cooling, adding water and toluene, 
transferring the mixture into a separating funnel, washing the resulting 
organic layer with 2N-NaOH aqueous solution, washing with water, 
distilling off the solvent under reduced pressure and recrystallizing the 
residue in a freezer to obtain the objective optically active 
(S)-2-p-5-methyl-heptyloxy-m-fluorophenyl)-5-octylpyridine (1.8 g). 
This product had the following phase transition points: 
C-S.sub.c *: 33.0.degree. C., S.sub.c *-SA: 33.5.degree. C., SA-I: 
39.4.degree. C. Further, the elemental analysis values accorded well with 
its calculated values as follows: 
______________________________________ 
Observed 
Calculated values 
values (%) 
(in terms of C.sub.27 H.sub.40 FNO) 
______________________________________ 
C 78.3 78.40 
H 9.6 9.75 
F 4.5 4.59 
N 3.3 3.39 
______________________________________ 
In the same manner as in this Example, it is possible to prepare any of the 
compounds of the formula (Ib) The values of physical properties of other 
representative examples are shown in Table 2. 
EXAMPLE 4 (USE EXAMPLE 1) 
Using the liquid crystal compounds of the present invention, the following 
composition in equal weights: 
##STR12## 
The resulting composition was filled in a cell 2 .mu.m thick, provided with 
transparent electrodes obtained by applying polyvinyl alcohol (PVA) as an 
agent for aligning treatment, followed by rubbing the resulting surface to 
subject it to parallel aligning treatment. The resulting liquid crystal 
element was provided between two sheets of crossed polarizers and an 
electric field was impressed. As a result, a change in the intensity of 
transmitted light was observed by impression of 20V. 
From the change in the intensity of transmitted light at that time was 
sought the response time to give about 500 .mu.sec at 25.degree. C. 
In addition, the above composition exhibits a m.p. of 5.degree. C. and a 
S.sub.c *-SA transition point of 34.degree. C. Its supercooled state is 
observed down to -45.degree. C. and the composition has S.sub.c * phase as 
far as this temperature and also no other smectic phase appears. 
EXAMPLE 5 (USE EXAMPLE 2) 
Using a liquid crystal compound of the present invention (sample No. a21) 
and other optically active, chiral smectic liquid crystal compounds, a 
liquid crystal composition having the following components was prepared: 
__________________________________________________________________________ 
Sample No. a21 
__________________________________________________________________________ 
##STR13## 40 wt. % 
##STR14## 20 wt. % 
##STR15## 20 wt. % 
##STR16## 20 wt. % 
__________________________________________________________________________ 
The resulting composition was filled in the same cell of 2 .mu.m thick as 
in Example 4, and the resulting liquid crystal element was provided 
between two sheets of crossed polarizers and an electric field was 
impressed. As a result, a change in the intensity of transmitted light was 
observed by impression of 20V. 
From the change in the intensity of transmitted light was sought the 
response time to give a value of about 200 .mu.sec at 25.degree. C. 
The upper limit temperature of S.sub.c * phase of the above liquid crystal 
composition was 57.degree. C., and no crystallization could be observed. 
Observation was carried out down to -50.degree. C., but no smectic phase 
other than S.sub.c * phase appeared. The value of spontaneous polarization 
was 8 nC/cm.sup.2 and the tilt angle was 29.degree.. 
In addition, a mixture having removed sample No. a21 of the present 
invention from the above composition, i.e. consisting only of the above 
three components each in equal weights exhibited the following complicated 
phase transitions: 
##STR17## 
and the temperature range of S.sub.c * phase was 61.degree.-94.degree. C. 
As described above, the compounds of formula (I) are effective in spreading 
the temperature range of Sc* phase, particulary the lower range thereof. 
EXAMPLE 6 (USE EXAMPLE 3) 
Compounds of sample Nos. a16, a17, a11, a15 and a23 are blended at the 
respective ratios of 5%, 5%, 20%, 30% and 40% by weight to obtain a high 
dielectric liquid crystal composition having phase transition points of 
C-S.sub.c *: 15.degree. C., S.sub.c *-SA 40.3.degree. C., and SA-I: 
46.3.degree. C. at room temperature. Further, if this temperature range is 
insufficient, it is possible to make it more sufficient to meet an ordinal 
use by adding another liquid crystal having smectic C phase or chiral 
smectic C phase. 
EXAMPLE 7 (USE EXAMPLE 4) 
A nematic liquid crystal composition consisting of 
______________________________________ 
##STR18## 20 wt. % 
##STR19## 40 wt. % 
##STR20## 25 wt. % 
##STR21## 15 wt. % 
______________________________________ 
was filled in a cell composed of transparent electrodes obtained by 
applying PVA as an agent for aligning treatment, followed by rubbing the 
resulting surface to subject it to a parallel aligning treatment, and 
having a distance between the electrodes, of 10 .mu.m to prepare a TN type 
display cell, which was then observed under a polarizing microscope. As a 
result, a reverse twist domain was observed to be formed. 
To the above nematic liquid composition was added a compound (sample No. 
a28 in Table 1) i.e. 
##STR22## 
in 1% by weight, and the resulting composition was similarly observed in a 
TN type cell. As a result, the reverse twist domain was dissolved and a 
uniform nematic phase was observed.