Achiral fluorine-containing liquid crystals

Abstract: Achiral fluorine-containing liquid crystal compounds are provided. The compounds comprise a fluorocarbon terminal portion and a hydrocarbon or another fluorocarbon terminal portion, the terminal portions being connected by a central core, the compounds having smectic mesophases or having latent smectic mesophases. The compounds are useful in liquid crystal display devices both alone and in mixtures with other materials. Also provided is a process for preparing these compounds.

Description: FIELD OF THE INVENTION This invention relates to achiral smectic liquid crystals and methods for their preparation. These achiral liquid crystals and mixtures which contain them are useful in a variety of electrooptical displays. BACKGROUND OF THE INVENTION Devices employing liquid crystals have found use in a variety of electrooptical applications, in particular those which require compact, energy-efficient, voltage-controlled light valves, such as watch and calculator displays, and flat-panel displays as are found in portable computers and compact televisions. Liquid crystal displays have a number of unique characteristics, including low voltage and low power of operation, which make them the most promising of the non-emissive electrooptical display candidates currently available. However, slow response and insufficient nonlinearity can impose limitations for many potential applications. The requirement for speed may become especially important in proportion to the number of elements which have to be addressed in a device. This limits the potential use of some types of liquid crystals. Twisted nematic (TN), supertwisted birefringence effect (SBE), and dynamic scattering (DS), all employing nematic or chiral nematic (cholesteric) liquid crystals, are the modes of liquid crystal displays that are most extensively employed at present. These devices are based upon the dielectric alignment effects (Freedericksz effect) of the nematic and/or chiral nematic liquid crystal or mixtures of nematic or chiral nematic liquid crystals upon application of an electric field. The average molecular long axis of the liquid crystal material takes up a preferred orientation in the applied electric field, the orientation of which is dependent on the sign of the dielectric anisotropy of the material or mixture, and this orientation relaxes upon removal of the applied electric field. This reorientation and relaxation is slow, on the order of a few milliseconds. Although nematic and chiral nematic liquid crystals are the most extensively employed, there are liquid crystal devices that employ higher ordered smectic liquid crystals. Devices employing materials with a smectic A mesophase are useful in device applications as described in Crossland, et al. U.S. Patent Nos. 4,411,494; 4,419,664; and 4,528,562; and F. J. Kahn (Appl. Phys. Lett., vol. 22, p. 111 (1973). These devices are based on the dielectric reorientation of the liquid crystals and response times are on the order of milliseconds. Mixtures which exhibit a chiral smectic A mesophase are useful in a device as described by Lagerwall, et al. 1st International Symposium On Ferroelectric Liquid Crystals, Bordeaux-Arcachon, France, 1987. These mixtures exhibit an electrooptic effect which is termed a soft-mode ferroelectric effect and sub-microsecond switching can be achieved. Devices employing materials with a smectic C mesophase are useful in device applications as described by Pelzl, et al. (Kristall Technik., vol. 14, p. 817 (1979); Mol. Cryst. Liq. Cryst., vol 53, p. 167 (1979); Liquid Crystals, vol. 2, p. 21 (1987); and Liquid Crystals, vol. 2, p. 131 (1987)). These devices are based on the dielectric reorientation of the liquid crystals and the response times are slow. WO-A-87/06602 discloses the use of trifluorotoluene derivates as smectic liquid crystal phases A recent advance in the liquid crystal art has been the utilization of tilted chiral smectic liquid crystals, which are also termed ferroelectric liquid crystals, in devices which give microsecond switching and bistable operation not possible in any of the device applications described above. Ferroelectric liquid crystals were discovered by R. B. Meyer, et al. (J. Physique, vol 36, pp. 1-69 (1975). A high speed optical switching phenomenon was discovered for the ferroelectric liquid crystals by N. A. Clark, et al. (Appl. Phys. Lett., vol. 36, p. 899 (1980) and U.S. Patent No. 4,367,924). The high speed switch of the ferroelectric liquid crystals can be utilized in many applications: light valves, displays, printer heads, and the like. In addition to the submicrosecond switching speeds, some ferroelectric device geometries exhibit bistable, threshold sensitive switching, making them candidates for matrix addressed devices containing a large number of elements for passive displays of graphic and pictorial information, as well as, for optical processing applications. SUMMARY OF THE INVENTION The present invention provides achiral fluorine-containing liquid crystal compounds comprising a fluorocarbon terminal portion and a hydrocarbon or another fluorocarbon terminal portion, the terminal portions being connected by a central core, the compounds having smectic mesophases or having latent smectic mesophases. Compounds having latent smectic mesophases are those which by themselves do not exhibit a smectic mesophase, but when the compounds are in admixture with said compounds having smectic mesophases or other said compounds having said latent smectic mesophases develop smectic mesophases, under appropriate conditions. The abovementioned specified fluorocarbon terminal terminal portion can be represented by the formula -DC q F 2q+1 where q is 1-20, and D is -O-(CH₂) r -, -(CH₂) r -, -OSO₂-, -SO₂-, -SO₂(CH₂) r -, -O(CH₂) r -O(CH₂) r' -, or where r and r' are independently 1 to 20 and p is 0 to 4. In general, the compounds of this invention have a central core comprised of at least two aromatic, heteroaromatic, cycloaliphatic, or subsituted aromatic, heteroaromatic, or cycloaliphatic rings. The aromatic or heteroaromatic ring may be selected from fused aromatic, heteroaromatic, or non-fused aromatic or heteroaromatic rings, and the rings may be connected one with another by means of functional groups selected from -COO-, -COS-, -HC=N-, -COSe-. Heteroatoms within the heteroaromatic ring comprise at least one atom selected from N, O, or S. Achiral fluorine-containing liquid crystal compounds of this invention have a number of desirable properties such as good chemical stability toward water, weak acids and weak bases. They do not undergo degradation during normal use in a liquid crystal display device. They are photochemically stable, that is, they do not easily undergo photochemical reactions. These compounds, due to the novel fluorocarbon terminal portion, have greatly enhanced smectogenic properties, lower birefringences, and lower viscosities that their non-fluorine-containing analogues. These achiral fluorinated liquid crystals and mixtures which contain them are useful in a variety of electrooptical displays. In particular, these fluorinated materials exhibit smectic mesophases, especially smectic A and C, and are useful in the formation of smectic A (SmA), smectic C (SmC), chiral smectic A (SmA*), and chiral smectic C (SmC*) mixtures. Further provided are processes for preparing the achiral fluorine-containing liquid crystal compounds of the invention comprising the steps of (1) mixing at least one compound represented by the formula with at least one compound represented by the formula or (2) mixing at least one compound represented by the formula with at least one compound represented by the formula where M, N, and P are each independently a, b, and c are each independently zero or an integer of from 1 to 3 with the proviso that the sum of a+b+c be at least 2; each A and B are independently nil, -CH=N-, -CH₂-O-, or -O-, -CH₂CH₂-, -CH=CH-, or -C≡C-; each A', A'', B', and B'' are independently -OH, -COOH, -CH(CH₂OH)₂, -SH, -SeH, -TeH, -NH₂, -COCl, -CHO, or -CH₂COOH with the proviso that A' can enter into an addition or condensation reaction with A'' and B' can enter into an addition or condensation reaction with B''; each X, Y, and Z are independently -H, -Cl, -F, -OCH₃, -OH, -CH₃, -NO₂, -Br, -I, or -CN; each 1, m, and n are independently zero or an integer of 1 to 4; R is -OC q H 2q -OC q' H 2q'+ 1 , -C q H 2q -O-C q' H 2q'+1 , -C q H 2q -R', -O-C q H 2q -R', or where R' is -H, -Cl, -F, -CF₃ , -NO₂ , -CN, or and q and q' are independently 1 to 20; D is -O-(CH₂) r -, -(CH₂) r -,-OSO₂-, -SO₂-, -SO₂-(CH₂) r -, -O(CH₂) r -O(CH₂) r' -, or where r and r' are independently 1 to 20, and p is 0 to 4; R f is -C q F 2q+1 where q and q' are independently 1 to 20; and allowing said A' and A'' or B' and B'' to react in the presence of suitable coupling agents. Still further provided are liquid crystal devices comprising the achiral fluorine-containing liquid crystal compounds of the invention. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to achiral fluorine-containing liquid crystal compounds and mixtures derived therefrom which find use in smectic liquid crystal display applications. The liquid crystals of the present invention can be represented by the general formula I: where M, N, and P are each independently a, b, and c are each independently zero or an integer of from 1 to 3 with the proviso that the sum of a + b + c be at least 2; each A and B are non-directionally and independently nil, -CH₂CH₂-, -CH=CH-, -C≡C-, -CH=N- -CH₂-O-, or -O- ; each X, Y, and Z are independently -H, -Cl, -F, -Br, -I, -OH, -OCH₃, -CH₃, -CN, or -NO₂; each l, m, and n are independently zero or an integer of 1 to 4, D is -O-(CH₂) r -, -(CH₂) r -, -OSO₂-, -SO₂-, -SO₂-(CH₂) r -, -O(CH₂) r -O-(CH₂) r' -, or where r and and r' are independently 1 to 20, and p is 0 to 4; R is -O-C q H 2q -O-C q' H 2q'+1 , -C q H 2q -O-C q' H 2q'+1 , -C q H 2q -R', -O-C q H 2q -R', or where R' is -Cl, -F, -CF₃, -NO₂, -CN, -H, or and q and q' are independently 1 to 20, and R can be straight chain or branched, and R f is C q F 2q+1 where q and q' are independently 1 to 20. The birefringence of the materials of this invention are reduced dramatically by the incorporation of fluorine. Materials of the present invention have birefringences typically in the range of 0.05-0.18 depending on the ring systems present and the number of rings, while the corresponding non-fluorine-containing materials have birefringences in the range of 0.10-0.26 for materials which data is available for. Surprisingly, the smectic liquid crystals of the present invention have suppressed nematic mesophases, i.e. the materials of this invention, because of the incorporation of the novel fluorocarbon terminal portion, exhibit no or very small nematic mesophase temperature ranges as compared to their corresponding non-fluorinated liquid crystal analogues. The liquid crystals of the present invention have enhanced smectic mesophases as compared to their non-fluorine-containing liquid crystal analogues. Thus, the fluorine-containing materials of this invention, when compared to the corresponding non-fluorine-containing analogues, exhibit no or very little nematic liquid crystal behavior and enhanced smectic liquid crystal behavior. This phenomenon of enhanced smectic behavior by the substitution of the partially fluorinated terminal portion of this invention for one or both hydrocarbon terminal portions is general for the materials of this invention. Chain fluorination induces a higher order in the molecule that the non-fluorine-containing analogs and thus nematic mesophases are lost or greatly narrowed and smectic mesophases are introduced or enhanced. It is believed that the incompatibility of the fluorophilic portions, i.e., the fluorine-containing terminal portions, and the fluorophobic portions, i.e., the hydrocarbon core and terminal portions, of the materials lead to the higher ordering. This belief is supported by the fact that introduction of a hydrogen atom on the terminal carbon portion of a highly fluorinated chain generally results in a narrow smectic phase temperature range due to unfavorable dipole-dipole interactions at the smectic layer interface. These properties make these materials more suitable for use in smectic liquid crystal device applications than non-fluorine-containing materials. They have broader smectic liquid crystal temperature ranges. The lower birefringence results in less restrictive design parameters than with previously known smectic liquid crystals. The lower viscosity results in faster response times for all of the device applications utilizing the smectic liquid crystal materials of the present invention. Further, mixtures of the compounds of the invention, with other materials of this invention or with other liquid crystal materials not of this invention or with a combination thereof, can be formulated to provide desired transition temperatures and broad mesophase temperature ranges. The individual compounds of this invention which exhibit smectic A behavior can be used by themselves or in admixture with other materials, of this invention or not, is smectic A device applications (see Crossland, et al. U.S. Patent Nos. 4,411,494; 4,419,664; and 4,528,562, and F. J. Kahn (Appl. Phys. Lett., vol. 22, p. 111 (1973). Their low viscosity results in faster reorientation effects compared to their non-fluorine-containing analogues. This individual compounds of this invention which exhibit smectic C behavior can be used by themselves or in admixture with other materials, of this invention or not, in the smectic C Freedericksz device application described by Pelzl, et al., (see Kristall Technik., vol. 14, p. 817 (1979); Mol. Cryst. Liq. Cryst., vol 53, p. 167 (1979); Liquid Crystals, vol. 2, p. 21 (1987); and Liquid Crystals, vol. 2, p. 131 (1987)). As pointed out in the studies of Pelzl, et al. the decay time in the smectic C phase is shorter than in the nematic phase of the same material and in some cases the rise times are shorter, making this type of device application preferential to utilizing nematics in the classical Freedericksz device mode for some applications. The rise and decay times for the materials examined by Pelzl, et al. were on the order of 2-100 milliseconds for a 50% change inthe measured light intensity. For materials of the present invention, rise and decay times of less than 1 millisecond have been observed for an 80% change in the light intensity. Rise and decay times of a few milliseconds for 80% change in the light intensity have been observed in room temperature mixtures. Devices utilizing materials of the present invention make practical the use of smectic C materials in place of nematic materials in Freedericksz type devices and significantly shorter rise and decay times are attainable. The compounds of this invention do not show chiral smectic (ferroelectric) liquid crystal behavior by themselves since they are achiral. However, a preferred embodiment of this invention comprises mixtures which contain materials of this invention with at least one chiral (optically active) component. The broad smectic C mesophase ranges of many of the materials of this invention make them useful and desirable as components in the formulation or broad smectic C eutectics, which become ferroelectric, or chiral smectic C, upon addition of a chiral additive. Other advantages of using the materials of this invention in the formulation of chiral smectic mixtures are the low birefringence and viscosity which can be obtained. The lower viscosity of these materials results in reduced response times for the ferroelectric switching for a given bulk polarization value. The lower birefringence of these materials allows the fabrication of devices with larger device spacings. Light transmission through a surface-stabilized ferroelectric device (as described in U.S. Patent No. 4,367,924,) with two polarizers is represented by the following equation: I = I o (sin² (4Θ)) (sin² (πΔnd/λ)) where I o = transmission through parallel polarizers Θ = material tilt angle Δn = liquid crystal birefringence d = device spacing λ = wavelength of light used To maximize the transmission, both sin² (4Θ) and sin²(πΔnd/λ) must be at maximum. This occurs when each term equals one. The first term is a maximum when the tilt angle equals 22.5. This is a function of the liquid crystal and is constant for a given material at a given temperature. The second term is maximum when πΔnd =λ/2 . This demonstrates the criticality of the low birefringence of the materials of this invention. Low birefringence allows a larger device thickness, d for a given wavelength of light. Thus, a larger device spacing is possible while still maximizing transmission, allowing easier device construction. The fluorine-containing precursor compounds are those compounds that are used to synthesize the achiral fluorine containing liquid crystal compounds of this invention. Briefly, commercially available materials were chemically transformed by reaction pathways well-known to those skilled in the art and detailed in the examples. Chemical transformations were comprised of acylation, esterification, etherification, alkylation, and combinations thereof using fluorine-containing and non-fluorine contaniing chemicals to provide the precursor compounds, which, in turn were caused to react together to yield the achiral fluorine-containing liquid crystal compounds of this invention. Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention. In the following example, all temperatures are in degrees Centigrade and all parts and percentages are by weight unless indicated otherwise. Compounds prepared in the various examples of this invention were characterized by their melting or boiling point and structures were confirmed by using at least one of the methods of analysis: elemental analysis, ¹H-, ¹⁹F-NMR, IR, and MS spectroscopies. Examples 1-45 describe procedures for preparing intermediate compounds useful in preparing the liquid crystal compounds of this invention. Examples 45-135 describe preparation of the liquid crystal compounds of this invention. Examples 136-142 describe individual compounds and mixtures incorporating compounds of this invention in liquid crystal devices. The trifluoroalkylsulfonate esters used in the examples were prepared using the method disclosed in U. S. Patent No. 3,149,595. using commercial trifluoromethanesulfonic anhydride in place of trifluoromethanesulfonyl fluoride. The 4-hexylbenzenethiol used in the examples was prepared using the method described in Vogel's "Textbook of Practical Organic Chemistry", 4th Ed., pp 645-5,656 (1978) from the chlorosulfonation of hexylbenzene with chlorosulfonic acid, and subsequent reduction of the 4-hexylbenzene sulfonyl chloride with Zn/H₂SO₄. The 2-Butyl-1,3-propanediol used in the examples was prepared by the reduction of 2-butyl diethylmalonate with LiAlH4 using the method of Demus, et al. in J. fur Prakt. Chem. , 323 , 902-913 (1981). The 4-acetoxybenzoic acid used in the examples was prepared by treatment of 4-hydroxybenzoic acid with acetic anhydride and sulfuric acid catalyst as described in "Introduction to Organic Laboratory Techniques", by Pavia, Lampman, and Kriz, 2nd Edition, pp. 32- 4 (1982). The trans -4-( trans -4-heptylcyclohexyl)cyclohexane-1-carboxylic acid used in the examples was prepared by base hydrolysis of Merck ZLI-1186 [ trans -1-cyano-4-( trans -4'-heptylcyclohexyl)cyclohexane] (Merck & Co., Rahway, NJ), followed by acidification with aqueous HCl. The 4-( trans -4-pentylcyclohexyl)benzoic acid used in the examples was prepared by base hydrolysis of Merck ZLI-1114 [1-cyano-4-( trans -4-pentylcylohexyl)benzene)] followed by acidification with aqueous HCl. The 4-decyl-4'-biphenylcarboxylic acid used in the examples was prepared by base hydrolysis of BDH K30 [4-cyano-4'-decylbiphenyl] (British Drug House, Poole, Great Britain) followed by acidification with aqueous HCl. The 4-decyloxy-4'-biphenylcarboxylic acid used in the examples was prepared by base hydrolysis of BDH M30 [4-cyano-4'-decyloxybiphenyl] followed by acidification with aqueous HCl. The trans -5-butyl-2-(4-phenylcarboxylic acid)-1,3-dioxane used in the examples was prepared using the procedure of Hsu in U.S. Patent No. 4,313,878. The methyl 3-chloro-4-hydroxybenzoate, methyl 3-methoxy-4- hydroxybenzoate, and methyl 2-chloro-4-hydroxybenzoate used in the examples were synthesized by refluxing the appropriate benzoic acid with an excess of methanol and sulfuric acid catalyst. The 1,1-dihydroperfluorobutyl 2-chloro-4-hydroxybenzoate used in the examples was synthesized by refluxing 2-chloro-4-hydroxybenzoic acid with an excess of 1,1-dihydroperfluorobutanol and sulfuric acid catalyst. All acid chlorides used in the examples were prepared by reacting the appropriate carboxylic acid with an excess of thionyl chloride under reflux, followed by removal of the excess thionyl chloride and distillation or recrystallization of the resulting acid chloride. Example 1 Sodium (0.58g, 25 mg. atoms) was reacted with 25 mL anhydrous methanol at 25°C until all of the sodium had reacted. Upon completion of the formation of the sodium methylate, methyl 4-hydroxybenzoate (3.8g, 25 mmol) was added. Excess methanol was removed under reduced pressure and about 25 mL toluene was added and removed under reduced pressure to remove any residual methanol. The solid residue was dissolved in about 100 mL of 2:1 toluene-N,N-dimethylformamide (DMF) and 1,1-dihydroperfluorobutyl trifluoromethylsulfonate (8.3g, 25 mmol) was added dropwise. The mixture was refluxed for 1 day, allowed to cool, and washed with three 100 mL portions of water. The separated organic layer was dried (anhydrous MgSO₄), filtered, and concentrated by reduced pressure. The resulting crude methyl 4-(1,1-dihydroperfluorobutoxy)benzoate was refluxed in 100 mL of 10% aqueous sodium hydroxide for 2 hours. The reaction product was cooled and carefully acidified with concentrated aqueous HCl. The precipitated solid was collected by filtration, washed several times with cool water, and purified by recrystallization from ethanol-water to provide, 6.42g, (80% yield) of product, 4-(1,1-dihydroperfluorobutoxy)benzoic acid. Examples 2-14 The compounds of Examples 2-14 were prepared in the same manner as described in Example 1, except that in Example 2, 1,1-dihydroperfluoroethyl trifluoromethylsulfonate (5.80 g, 25 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate, in Example 3, 1,1-dihydroperfluoropropyl trifluoromethylsulfonate (7.05 g, 25 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate, in Example 4, 1,1-dihydroperfluorohexyl trifluoromethylsulfonate (10.80 g, 25 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate, in Example 5, 1,1-dihydroperfluorooctyl trifluoromethylsulfonate (13.30 g, 25 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate, in Example 6, 1,1-dihydroperfluorohexyl trifluoromethylsulfonate (6.48 g, 15 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 3-chloro-4-hydroxybenzoate (2.79 g, 15 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 7, 1,1-dihydroperfluorooctyl trifluoromethylsulfonate (5.32 g, 10 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 2-chloro-4-hydroxybenzoate (1,87 g, 10 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 8, 1,1-dihydroperfluorooctyl trifluoromethylsulfonate (5.32 g, 10 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 3-chloro-4-hydroxybenzoate (1.87 g, 10 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 9, 1,1-dihydroperfluorohexyl trifluoromethylsulfonate (10.80 g, 25 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 2-chloro-4-hydroxybenzoate (4.66 g, 25 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 10, 1,1-dihydroperfluorohexyl trifluoromethylsulfonate (12.6 g, 30 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 3-methoxy-4-hydroxybenzoate (5.46 g, 30 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 11, methyl 2-chloro-4-hydroxybenzoate (7.00 g, 37.5 mmol) was substituted for the methyl 4-hydroxybenzoate and 1,1-dihydroperfluorobutyl trifluoromethylsulfonate was used, (12.45 g, 37.5 mmol), in Example 12, 1-bromooctane (19.3 g, 100 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 3-methoxy-4-hydroxybenzoate (18.2 g, 100 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 13, 1-bromooctane (19.3 g, 100 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and methyl 3-chloro-4-hydroxybenzoate (18.7 g, 100 mmol) was substituted for the methyl 4-hydroxybenzoate, in Example 14, benzyl chloride was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate . The compounds thus produced were 4-(1,1-dihydroperfluoroethoxy)benzoic acid (Example 2), 4-(1,1-dihydroperfluoropropoxy)benzoic acid (Example 3), 4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 4), 4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 5), 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 6), 2-chloro-4-(1,1-dihydroperfluorooctyloxy)-benzoic acid (Example 7), 3-chloro-4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 8), 2-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 9), 3-methoxy-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 10), 2-chloro-4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 11), 3-methoxy-4-octyloxybenzoic acid (Example 12), 3-chloro-4-octyloxybenzoic acid (Example 13), and 4-benzyloxybenzoic acid (Example 14). Example 15 Sodium hydride (2.4 g, 0.1 mol) was suspended in 150 mL dry glyme. Monobenzylhydroquinone (20.0 g, 0.1 mol) was dissolved in 250 mL dry glyme and added dropwise to the sodium hydride suspension with stirring under nitrogen at room temperature. 1-Bromohexane (16.5 g, 0.1 mol) was added dropwise and the reaction mixture was refluxed for 1 day. The reaction product was cooled and the glyme removed under reduced pressure. The residue was dissolved in 300 mL 1:1 ethanol-ethyl acetate and catalytically hydrogenated using 2 g 10% Pd on C and a hydrogen pressure of 500 kPa at room temperature for 4 hours. The catalyst was removed by filtration and the solvent was removed from the filtrate under reduced pressure. The crude product residue was recrystallized from aqueous ethanol to yield 15 g 4-hexyloxyphenol. Examples 16-19 In Examples 16-19 which contain alkoxy groups different from those of Example 15 were prepared in the same manner as described in Example 15, except that in Example 16, 1-bromooctane (19.3 g, 100 mmol) was substituted for the 1-bromohexane, in Example 17, 1-bromodecane (22.1 g, 100 mmol) was substituted for the 1-bromohexane, in Example 18, 1-bromododecane (24.9 g, 100 mmol) was substituted for the 1-bromohexane, and in Example 19, 1-bromo-11-(perfluorooctyl)undecane (2.37 g, 5 mmol) was substituted for the 1-bromohexane and 5 mmol sodium hydride and monobenzylhydroquinone were used. The compounds thus produced were, respectively, 4-octyloxyphenol (Example 16), 4-decyloxyphenol (Example 17), 4-dodecyloxyphenol (Example 18), and 4-(11-perfluorooctylundecyloxy)phenol (Example 19). Example 20 Sodium hydride (5.0g, 0.21 mol) was suspended in 150 mL dry 1,2-dimethoxyethane (glyme). Monobenzylhydroquinone (40g, 0.20 mol) was dissolved in 500 mL dry glyme and added dropwise to the sodium hydride with stirring under nitrogen. Upon completion of the addition,the mixture was stirred at room temperature for 1 hour and then cooled to -78°C. 1,1-Dihydroperfluorobutyl trifluoromethylsulfonate (70.0g, 0.21 mol) was then added dropwise; upon completion of the addition, the reaction was allowed to warm slowly to room temperature. Glyme was removed under reduced pressure. The residue was diluted with 800 mL of water and 700 mL of ethyl ether and mixed vigorously. The separated ether layer was washed twice with about 500 mL 5% sodium hydroxide, twice with about 500 mL water, dried over anhydrous MgSO₄, filtered, and concentrated to provide 65g of a light orange-brown intermediate product. This intermediate product was dissolved in anhydrous ethanol and catalytically hydrogenated using a catalytic amount of 10% Pd/C catalyst and a hydrogen pressure of 500 kPa of room temperature for 2 hours. Catalyst was removed by filtration and ethanol was removed under reduced pressure. The crude phenol was purified by high performance liquid chromatography (HPLC, silica gel, methylene chloride), and the resultant solid was recrystallized from petroleum ether to produce the pure product, 4-(1,1-dihydroperfluorobutoxy)phenol, (59.3% yield). Examples 21-25 The compounds in Examples 21-25 which contain different fluorine-containing alkoxy groups from those of Example 20 were prepared in the same manner as described in Example 20, except that in Example 21, 1,1-dihydroperfluorohexyl trifluoromethylsulfonate (45 g, 105 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and monobenzylhydroquinone (20.0 g, 100 mmol) was used, in Example 22, 1,1-dihydroperfluorooctyl trifluoromethylsulfonate (58.5 g, 110 mmol) was substituted for the 1,1- dihydroperfluorobutyl trifluoromethylsulfonate and monobenzylhydroquinone (20.0 g, 100 mmol) was used, in Example 23, 1,1,2,2-tetrahydroperfluorohexyl trifluoromethylsulfonate (19.8 g, 50 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and monobenzylhydroquinone (10 g, 50 mmol) was used, in Example 24, 1,1-dihydroperfluoroethyl trifluoromethylsulfonate (11.6 g, 50 mmol) was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate and monobenzylhydroquinone (10 g, 50 mmol) was used, in Example 25, 1,1-dihydroperfluoropropyl trifluoromethylsulfonate (14.1 g, 50 mmol) was substituted for the 1,1-dihydroperfuorobutyl trifluoromethylsulfonate and monobenzylhydroquinone (10 g, 50 mmol) was used. The compounds thus-produced were 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21), 4-(1,1-dihydroperfluorooctyloxy)phenol (Example 22), 4-(1,1,2,2-tetrahydroperfluorohexyloxy)phenol (Example 23), 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24), 4-(1,1-dihydroperfluoropropoxy)phenol (Example 25). Example 26 4-Bromophenol ( 34.6g, 0.2 mol) was dissolved in 25 mL dry glyme and added dropwise to a suspension of sodium hydride (4.8g, 0.2 mol) in 25 mL dry glyme. Upon completion of the addition, the mixture was stirred at room temperature for 30 minutes and 25 mL of dry DMF was added. Hexyl bromide (36.3g, 0.22 mol) was then added and the mixture refluxed for 1 day. The reaction mixture was filtered and the glyme removed under reduced pressure. Methylene chloride (50 mL) was added to the residue and this solution was washed successively with about 50 mL water, about 50 mL 5% sodium hydroxide, about 50 mL water, dried over anhydrous MgSO₄, filtered, and concentrated under reduced pressure. Distillation gave 40.5g (79% yield) of product, 1-bromo-4-hexyloxybenzene, bp 142-3°C/5mm. Hg.(5 torr). Example 27 Magnesium (2.3g, 0.1 g. atom) was placed in a 250 mL flask and stirred without solvent for 15 minutes under dry nitrogen. Then dry tetrahydrofuran (THF) (100 mL) was then added to the flask. 1- Bromo-4-hexyloxybenzene (25.7g, 0.1 mol, Example 26) in 50 mL dry THF was placed in an addition funnel and 25% of this solution was added into the flask. This mixture was warmed carefully and once reaction began, the heat was removed and the rate of reflux was controlled by the rate of addition of the remainder of the 1-bromo-4-hexyloxybenzene solution. Upon completion of addition, the reaction mixture was refluxed for 2 hours, cooled to just below reflux and sulfur (3.2g, 0.1 g. atom) was added very carefully in portions. Upon completion of the addition of the sulfur, the reaction mixture was stirred at room temperature for 3 hours, filtered, and concentrated under reduced pressure. Ethyl ether (200mL) was added and 1M aqueous HCl was carefully added with vigorous stirring. The separated ether layer was washed with about 100 mL 1M HCl, about 100 mL water, dried over anhydrous MgSO₄, filtered, and concentrated under reduced pressure. the crude product was distilled, bp 145°/10mm, to provide 15.1g (72% yield) of product, 4-hexyloxythiophenol. Example 28 The compound of Example 28 was prepared using the procedure in Example 27, except that 1-bromoanisole was substituted for the 1-bromo-4-hexyloxybenzene. The compound thus produced was 4-methoxythiophenol. Example 29 Sodium (1.15g, 50 mg. atoms) was reacted with 50 mL anhydrous methanol, and upon completion of the formation of the sodium methylate, 4-hydroxybenzaldehyde (6.1g, 50 mmol) was added. Excess methanol was removed under reduced pressure and about 50 mL toluene was added and removed under reduced pressure to remove and residual methanol. The solid residue was dissolved in about 100 mL 2:1 toluene-DMF and 1,1-dihydroperfluorohexyloxy trifluoromethylsulfonate (21.6g, 50 mmol) was added all at once and the mixture refluxed for 1 day. The reaction product was cooled and washed with three 100 mL portions of water. The separated organic layer was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated. Distillation of the concentrate gave 13.1g (65%) of pure product, 4-(1,1-dihydroperfluorohexyloxy)benzaldehyde, bp 91-2°C/0.2 torr. Example 30 Sodium hydride (12.0 g, 50 mmol) was suspended in 25 mL diglyme and 2,6-dihydroxynapthalene (25 mmol) in 75 mL diglyme was added. The mixture was warmed for 1 hour at 150°C, then cooled, and 1,1-dihydroperfluorobutyloxy trifluoromethylsulfonate (4.15 g, 12.5 mmol) was added. The mixture was warmed for 2 days at 150°C, then cooled to room temperature. The reaction was acidified with 100 mL 3M HCl and twice extracted with about 100 mL ether. The combined organic extract was washed four times with about 100 mL water, dried over anhydrous MgSO₄, filtered, and concentrated. The crude concentrate was purified by HPLC using methylene chloride on a silica gel column to give 1.9g (44% yield) of product, 6-(1,1-dihydroperfluorobutoxy)-2-napthol. Examples 31-32 In Examples 31-32, compounds were prepared in the same manner as described in Example 32, except that in Example 31, 1,4-dihydroxynapthalene (4.00 g, 25 mmol) was substituted for the 2,6-dihydroxynapthalene, in Example 32, 1,5-dihydroxynapthalene (4.00 g, 25 mmol) was substituted for the 2,6-dihydroxynapthalene and 1-bromooctane was substituted for the 1,1-dihydroperfluorobutyl trifluoromethylsulfonate. The compounds thus produced were 4-(1,1-dihydroperfluorobutoxy)-1-napthol (Example 31) and 5-octyloxy-1-napthol (Example 32). Example 33 Sodium ( 2.3g, 0.1 g. atom) was added to 100 mL decanol with stirring under nitrogen at room temperature. Upon completion of the reaction, 6-chloronicotinic acid (7.09g, 0.045 mol) was added and this mixture was refluxed for 2 days. The reaction mixture was acidified with 300 mL 0.5M HCl and the product was extracted 3 times with about 50 mL portions of petroleum ether. The extracts were combined, dried over anhydrous MgSO₄, filtered, and the filtrate was concentrated to leave a crude material which was twice recrystallized from heptane to provide 5.2g (41% yield) of product, 6-decyloxynicotinic acid. Example 34 In this example, a compound was prepared in the same manner as that described in Example 33, except that dl -4-methylhexanol was substituted for the decanol to provide dl -6-(4-methylhexyloxy)nicotinic acid. Example 35 Sodium hydride (1.44 g, 0.06 mol) was suspended in 50 mL dry glyme and 1,1-dihydroperfluorobutanol (6.0 g, 0.03 mol) was added dropwise with stirring under nitrogen at room temperature. Upon completion of the addition, 6-chloronicotinic acid (4.71 g, 0.03 mol), dissolved in 100 mL diglyme and 50 mL cyclohexanone, was added and this mixture was refluxed for 1 day. The reaction mixture was acidified with 150 mL 0.5M HCl and the product was extracted three times with about 50 ml portions of ethyl ether. The separated ether extracts were combined, dried over anhydrous MgSO₄, filtered, and the filtrate was concentrated. The crude material was twice recrystallized from heptane to provide 2.63 g (27% yield) of product, 6-(1,1-dihydroperfluorobutoxy)nicotinic acid, containing a small amount of starting 6-chloronicotinic acid. Example 36 4-Benzyloxyphenol (10.0 g, 0.05 mol), 4-(1,1-dihydroperfluorobutoxy)benzoic acid (16.0 g, 0.05 mol) prepared as in Example 1, and 4-dimethylaminopyridine (0.1 g) were dissolved in 100 ml methylene chloride. Dicyclohexylcarbodiimide (11.0 g, 0.053 mol) was then added in one portion. The reaction mixture was stirred at 25°C under a nitrogen atmosphere for 12 hours. The reaction product was filtered, and the filtrate was washed sequentially with about 100 mL 0.5N hydrochloric acid, about 100 mL 5% aqueous sodium bicarbonate, and about 200 mL water. The organic phase was separated, dried over anhydrous MgSO₄, filtered, and the filtrated concentrated to yield 22 g of 4-benzyloxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate after recrystallization from ethanol. Examples 37-38 In Examples 37-38, compounds were prepared as in Example 36, except that in Example 37, 4-benzyloxybenzoic acid (2.28 g, 10 mmol, Example 14) was substituted for the 4-(1,1-dihydroperfluorobutoxy)benzoic acid and 1,1-dihydroperfluorobutanol (2.00 g, 10 mmol) was substituted for the 4-benzyloxyphenol, in Example 38, 4-benzyloxybenzoic acid (2.28 g, 10 mmol, Example 14) was substituted for the 4-(1,1-dihydroperfluorobutoxy)benzoic acid and 1,1-dihydroperfluorohexanol (3.00 g, 10 mmol) was substituted for the 4-benzyloxyphenol. The compounds thus-produced were 1,1-dihydroperfluorobutyl 4-benzyloxybenzoate (Example 37) and 1,1-dihydroperfluorohexyl 4-benzyloxybenzoate (Example 38). Example 39 4-Benzyloxyphenol (20.0 g, 100 mmol) was dissolved in 200 mL dry ether and 10 mL triethylamine. 4-Decyloxybenzoyl chloride (30.0 g, 100 mmol) was added dropwise with stirring at room temperature under nitrogen. After 1 day of stirring at room temperature under nitrogen atmosphere, 200 mL toluene and 200 mL methylene chloride were added to the reaction mixture. The reaction mixture was then filtered and the filtrate washed twice with 0.5N HCl, once with water, and dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The crude product was recrystallized from toluene-ethanol to provide 43.9 g (95% yield) 4-benzyloxyphenyl 4-decyloxybenzoate. Example 40 Example 40, a compound was prepared as in Example 39 except that monobenzylhydroquinone (10 g, 50 mmol) was used and 4-decylbenzoyl chloride (14.0 g, 50 mmol) was substituted for the 4-decyloxybenzoyl chloride. The thus-produced compound was 4-benzyloxyphenyl 4-decylbenzoate. Example 41 4-Benzyloxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (22 g, 0.0438 mol), prepared as in Example 36, was dissolved in 200 mL of 50:50 by volume ethanol-ethyl acetate and hydrogenated at 500 kP hydrogen pressure over 2.0 g 10% palladium on carbon catalyst at 25°C for 2 hours. The reaction mixture was filtered to remove catalyst and the filtrate was concentrated under reduced pressure to leave 17.3 g 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate. Examples 42-45 In Examples 42-45, compounds were prepared as in Example 41, except that in Example 42, 1,1-dihydroperfluorobutyl 4-benzyloxybenzoate prepared as in Example 37 was substituted for the 4-benzyloxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate, in Example 43, 1,1-dihydroperfluorohexyl 4-benzyloxybenzoate prepared as in Example 38 was substituted for the 4-benzyloxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate, in Example 44, 4-benzyloxyphenyl 4-decyloxybenzoate prepared as in Example 39 was substituted for the 4-benzyloxyphenyl 4-(1,1-dihydroperfluorobutoxy)-benzoate, and in Example 45, 4-benzyloxyphenyl 4-decylbenzoate prepared as in Example 40 was substituted for the 4-benzyloxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate. The compounds thus-produced were 1,1-dihydroperfluorobutyl 4-hydroxybenzoate (Example 42), 1,1-dihydroperfluorohexyl 4-hydroxybenzoate (Example 43), 4-hydroxyphenyl 4-decyloxybenzoate (Example 44), 4-hydroxyphenyl 4-decylbenzoate (Example 45). Example 46 To a solution of 4-hexyloxythiophenol (1.05g, 5 mmol; synthesized in Example 27) in 30 mL dry ethyl ether containing 1 mL of dry triethylamine, 4-(1,1-dihydroperfluorobutoxyoxy)benzoic acid chloride (1.70g, 5 mmol; derived from the material synthesized in Example 1), was added dropwise. The reaction mixture was stirred for 1 day at room temperature at which time it was filtered, the filtrate was washed successively with about 50 mL 0.5 M HCl, about 50 mL water, dried over anhydrous MgSO₄, filtered, and the filtrate concentrated under reduced pressure. The crude residue was purified by HPLC (toluene, silica gel) followed by recrystallization from anhydrous ethanol to provide 2.17g (82% yield) of 4-(1,1-dihydroperfluorohexyloxy)thiolbenzoic acid 4′-hexyloxyphenyl ester (compound 1 of Table I) whose structure was confirmed by proton- and fluorine-nuclear magnetic resonance, mass spectrometry, and infrared spectroscopy. Examples 47-48 In Examples 47-48, compounds 2-3 of Table I were prepared as in Example 46 except that the precursor compounds indicated below were substituted for the 4-hexyloxythiophenol and for the 4-(1,1-dihydroperfluorobutoxy)benzoic acid chloride. Example 47, Compound 2, was prepared from 4-hexylthiophenol and 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1). Example 48, compound 3, was prepared from 4-methoxythiophenol (Example 28) and 4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 5). Example 49 4-Decyloxybenzoic acid (0.70g, 2.5 mmol) and 4-(1,1-dihydroperfluorobutoxy)phenol (0.73, 2.5 mmol, synthesized in Example 20) were dissolved in 50 mL methylene chloride. 4-(N,N-Dimethylamino)pyridine (0.1g) was added to the reaction mixture followed by N,N′-dicyclohexylcarbodiimide (0.52g, 2.5 mmol). The reaction product was stirred at room temperature under nitrogen for 1 day, filtered and washed successively with about 50 mL 0.5 M HCl, about 50 mL 5% sodium bicarbonate, and about 50 mL water. The separated organic layer was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated under reduced pressure. The crude material was purified by HPLC (toluene, silica gel) followed by recrystallization from ethanol to provide 1.02g (74% yield) of 4-decyloxybenzoic acid 4′-(1,1-dihydroperfluorobutoxy)phenyl ester, (compound 4, Table I) characterized by proton- and fluorine-nuclear magnetic resonance, mass spectrometry, and infrared spectroscopy. Examples 50-101 In Examples 50-101, compounds 5-56 of Table I were prepared as in Example 49, except that the precursor compounds indicated below were substituted for the 4-decyloxybenzoic acid and the 4-(1,1-dihydroperfluorobutoxy)phenol. Example 50, compound 5, was prepared from 4-decyloxybenzoic acid and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24). Example 51, compound 6, was prepared from 4-decyloxybenzoic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 52, compound 7, was prepared from 4-decyloxybenzoic acid and 4-(1,1-dihydroperfluorooctyloxy)phenol (Example 22). Example 53, compound 8, was prepared from 4-decyloxybenzoic acid and 4-(1,1,2,2-tetrahydroperfluorohexyloxy)phenol (Example 23). Example 54, compound 9, was prepared from 4-decyloxybenzoic acid and 1-(4-hydroxyphenoxy)-11-perfluorooctylundecane (Example 19). Example 55, compound 10, was prepared from 4-butoxybenzoic acid and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24). Example 56, compound 11, was prepared from 4-butoxybenzoic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 57, compound 12, was prepared from 4-hexyloxybenzoic acid and 4-(1,1-dihydroperfluorobutoxy)phenol (Example 20). Example 58, compound 13, was prepared from 4-hexyloxybenzoic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 59, compound 14, was prepared from 4-hexyloxybenzoic acid and 4-(1,1-dihydroperfluorooctyloxy)phenol (Example 22). Example 60, compound 15, was prepared from 4-octyloxybenzoic acid and 4-(1,1-dihydroperfluorobutoxy)phenol (Example 20). Example 61, compound 16, was prepared from 4-octyloxybenzoic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 62, compound 17, was prepared from 4-octyloxybenzoic acid and 4-(1,1-dihydroperfluorooctyloxy)phenol (Example 22). Example 63, compound 18, was prepared from 4-decylbenzoic acid and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24). Example 64, compound 19, was prepared from 4-decylbenzoic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 65, compound 20, was prepared from 4-dodecyloxybenzoic acid and 4-(1,1-dihydroperfluorooctyloxy)phenol (Example 22). Example 66, compound 21, was prepared from 3-chloro-4-octyloxybenzoic acid (Example 13) and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24). Example 67, compound 22, was prepared from 4-(1,1-dihydroperfluoroethoxy)benzoic acid (Example 2) and 4-hexyloxyphenol. Example 68, compound 23, was prepared from 4-(1,1-dihydroperfluoropropoxy)benzoic acid (Example 3) and 4-hexyloxyphenol. Example 69, compound 24, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-hexyloxyphenol (Example 15). Example 70, compound 25, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-heptyloxyphenol. Example 71, compound 26, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-octyloxyphenol (Example 16). Example 72, compound 27, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-decyloxyphenol (Example 17). Example 73, compound 28, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-dodecyloxyphenol (Example 18). Example 74, compound 29, was prepared from 4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 4) and 4-hexyloxyphenol (Example 15). Example 75, compound 30, was prepared from 4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 4) and 4-heptyloxyphenol. Example 76, compound 31, was prepared from 4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 4) and 4-octyloxyphenol (Example 16). Example 77, compound 32, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-decyloxyphenol (Example 17). Example 78, compound 33, was prepared from 4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 5) and 4-hexyloxyphenol (Example 15). Example 79, compound 34, was prepared from 4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 5) and 4-octyloxyphenol (Example 16). Example 80, compound 35, was prepared from 4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 5) and 4-decyloxyphenol (Example 17). Example 81, compound 36, was prepared from 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 6) and 4-decyloxyphenol (Example 17). Example 82, compound 37, was prepared from 2-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 9) and 4-decyloxyphenol (Example 17). Example 83, compound 38, was prepared from 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 6) and 4-octyloxyphenol (Example 16). Example 84, compound 39, was prepared from 2-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 9) and 4-octyloxyphenol (Example 16). Example 85, compound 40, was prepared from 3-chloro-4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 8) and 4-decyloxyphenol (Example 17). Example 86, compound 41, was prepared from 2-chloro-4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 7) and 4-decyloxyphenol (Example 17). Example 87, compound 42, was prepared from 4-octyloxybenzoic acid and 1,1-dihydroperfluorobutyl 2-chloro-4-hydroxybenzoate. Example 88, compound 43, was prepared from 4-decyloxybenzoic acid and 1,1-dihydroperfluorobutyl 2-chloro-4-hydroxybenzoate. Example 89, compound 44, was prepared from 3-methoxy-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 10) and 4-decyloxyphenol (Example 17). Example 90, compound 45, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-cyanophenol. Example 91, compound 46, was prepared from 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 6) and 4-cyanophenol. Example 92, compound 47, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24). Example 93, compound 48, was prepared from trans -4-pentylcyclohexanecarboxylic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 94, compound 49, was prepared from trans -4-heptylcyclohexyl- trans -4′-cyclohexanecarboxylic acid and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24). Example 95, compound 50, was prepared from trans -4-heptylcyclohexyl- trans -4′-cyclohexanecarboxylic acid and 4-(1,1-dihydroperfluoroethoxy)phenol (Example 21). Example 96, compound 51, was prepared from 4-( trans -4-pentylcyclohexyl)benzoic acid and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 97, compound 52, was prepared from 4-decylbiphenyl-4′-carboxylic acid and 4-(1,1-dihydroperfluorobutoxy)phenol (Example 20). Example 98, compound 53, was prepared from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and 5-octyloxy-1-napthol (Example 32). Example 99, compound 54, was prepared from 4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 4) and 5-octyloxy-1-napthol (Example 32). Example 100, compound 55, was prepared from 4-decyloxybenzoic acid and 6-(1,1-dihydroperfluorobutoxy)-2-napthol (Example 30). Example 101, compound 56, was prepared from 4-octyloxybenzoic acid and 4-(1,1-dihydroperfluorobutoxy)-1-napthol (Example 31). Example 102 6-Decyloxynicotinic acid (2.79, 10 mmol), synthesized in Example 33, and 4-(1,1-dihydroperfluorohexyloxy)phenol (3.92, 10 mmol), synthesized in Examples 21, were dissolved in 50 mL methylene chloride. 4-(N,N-Dimethylamino)pyridine (0.1 g) was added to the reaction mixture followed by N,N′-dicyclohexylcarbodiimide (2.27 g, 11 mmol). The reaction mixture was refluxed under nitrogen for 1 day, cooled, filtered, and the filtrate was washed successively with about 50 mL 0.5 M HCl, about 50 mL 5% sodium bicarbonate, and about 50 mL water. The separated organic layer was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated under reduced pressure. The crude residue was purified by HPLC (toluene, silica gel) followed by recrystallization from heptane to provide 1.05 g (54% yield) of 6-decyloxynicotinic acid 4′-(1,1-dihydroperfluorohexyloxy)phenyl ester (compound 57, Table I) characterized by H- and F-NMR, MS, and IR spectroscopies. Examples 103-104 In Examples 103-104, compounds 58-59 of Table I were prepared as in Example 102 except that the precursor compounds indicated below were substituted for the 6-decyloxynicotinic acid and the 4-(1,1-dihydroperfluorohexyloxy)phenol. Example 103, compound 58, was prepared from 6-(4-methylhexyloxy)nicotinic acid (Example 34) and 4-(1,1-dihydroperfluorobutoxy)phenol (Example 20). Example 104, compound 59, was prepared from 6-(4-methylhexyloxy)nicotinic acid (Example 34) and 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Example 105 4-(1,1-Dihydroperfluorohexyloxy)benzaldehyde (1.01g, 2.5mmol), synthesized in Example 29, and 2-butyl-1,3-propanediol (0.33g, 2.5mmol) were dissolved in 40 mL of toluene containing a catalytic amount of p-toluenesulfonic acid. This mixture was brought to reflux and the water formed was collected as an azeotrope in a Dean-Stark water trap. After 4 hours the reaction mixture was cooled and washed with about 50 mL 5% NaHCO₃ and about 50 mL water. The organic phase was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated. The residue was recrystallized from anhydrous ethanol to provide 0.7g (54% yield) of compound 60, Table I, trans -5-butyl-2-(4-(1,1-dihydroperfluorohexyloxy)phenyl)-1,3-dioxane, whose structure was confirmed by H- and F-NMR, MS, and IR spectrosopies. Example 106 Trans -5-butyl-2-(4-phenylcarboxylic acid)-1,3-dioxane (0.26 g, 1.0 mmol), 4-(1,1-dihydroperfluorobutoxy)-phenol (0.29 g, 1.0 mmol, synthesized in Example 20), and 4-dimethylaminopyridine (0.01 g) were dissolved in 25 mL of methylene chloride and dicyclohexylcarbodiimide (0.22 g, 1.1 mmol) was added all at once. The resulting solution was stirred at room temperature under a nitrogen atmosphere for 1 day. The reaction mixture was filtered and the filtrate was washed successively with about 25 mL 0.5 M HCl, about 25 mL 5% sodium bicarbonate, and about 25 mL water. The separated organic layer was dried over anhydrous MgSO₄, filtered, and the filtrate was concentrated under reduced pressure. The crude material was purified by recrystallization from ethanol to provide 0.30 g (56% yield) of compound 61, Table I, trans -5-butyl-2-{4-[4-(1,1-dihydroperfluorohexyloxy)phenyloxycarbonyl]phenyl}-1,3-dioxane, whose structure was confirmed by H- and F-NMR, MS, and IR spectroscopies. Example 107 In Example 107, compound 62 of Table I was prepared as in Example 116 except that 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21) was substituted for the 4-(1,1-dihydroperfluorobutoxy)phenol. Example 108 This compound was prepared by two different procedures, A and B below. Procedure A. 1,1-Dihydroperfluorobutyl 4-hydroxybenzoate (1.60 g, 5 mmol, prepared in Example 42), was dissolved in 50 mL anhydrous ether. Triethylamine (1.0 g) was added followed by the dropwise addition of 4-octyloxybenzoyl chloride ( 1.34 g, 5 mmol). The reaction mixture was stirred for 1 day under a nitrogen atmosphere at room temperature. The reaction mixture was filtered, the filtrate was washed with about 50 mL 0.5N HCl, about 50 mL water, and the separated organic phase was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated. The crude product was recrystallized from ethanol to provide 2.03 g (74% yield) of compound 63, Table I, 4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester, whose structure was confirmed by H- and F-NMR, MS, and IR spectroscopies. Procedure B. Compound 63 was also prepared as in Example 49. 4-Octyloxybenzoic acid (1.25 g, 5 mmol), 1,1-dihydroperfluorobutyl 4-hydroxybenzoate (1.60 g, 5 mmol), and 4-dimethylaminopyridine (0.05g) were dissolved in 50 mL of methylene chloride. Dicyclohexylcarbodiimide (1.03g, 5 mmol) was added all at once. The reaction mixture was stirred at room temperature under nitrogen for 1 day, filtered, and the filtrate was washed successively with about 50 mL 0.5 M HCl, about 50 mL 5% sodium bicarbonate, and about 50 mL water. The separated organic layer was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated under reduced pressure to leave a crude material which was purified by recrystallization from ethanol to provide 2.07g (76% yield) of compound 63, Table I, 4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester. Examples 109-115 In Examples 109-115, compounds 64-70 of Table I were prepared as in Example 108 except that the precursor compounds indicated below were substituted for the 4-octyloxybenzoic acid chloride and the 1,1-dihydroperfluorobutyl 4-hydroxybenzoate. Examples 109, compound 64, was prepared according to Procedure A from 4-decyloxybenzoyl chloride and 1,1-dihydroperfluorobutyl 4-hydroxybenzoate (Example 42). Example 110, compound 65, was prepared according to Procedure A from 4-decyloxybenzoyl chloride and 1,1-dihydroperfluorohexyl 4-hydroxybenzoate (Example 43). Example 111, compound 66, was prepared according to Procedure A from 4-decylbenzoyl chloride and 1,1-dihydroperfluorobutyl 4-hydroxybenzoate (Example 42). Example 112, compound 67, was prepared according to Procedure B from 6-(4-methylhexyloxy)nicotinic acid (Example 36) and 1,1-dihydroperfluorobutyl 4-hydroxybenzoate (example 42). Example 113, compound 68, was prepared according to Procedure B from 3-chloro-4-octyloxybenzoic acid (Example 13) and 1,1-dihydroperfluorobutyl 4-hydroxybenzoate (Example 42). Example 114, compound 69, was prepared according to Procedure B from 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1) and methyl 4-hydroxybenzoate. Example 115, compound 70, was prepared according to Procedure B from 4-acetoxybenzoic acid and 4-(1,1-dihydroperfluorobutoxy)phenol (Example 20). Example 116 4-Hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (2.06 g, 5 mmol, synthesized in Example 41), and triethylamine (2.00 g) were dissolved in 50 mL anhydrous THF. 4-Octyloxybenzoyl chloride (1.34 g, 5 mmol) was added dropwise with stirring. Upon completion of the addition, the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 1 day. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure. The crude residue was recrystallized from toluene-ethanol to give 2.93 g, (91%) of compound 71, Table I,1-(4-octyloxybenzoyloxy)-4-(4-(1,1-dihydroperfluorobutoxy)benzoyloxy)benzene. Examples 117-125 In Examples 117-125, compounds 72-80 of Table I were prepared as in Example 116 except that the precursor compounds indicated below were substituted for the 4-octyloxybenzoyl chloride and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate. Example 117, compound 72, was prepared from 4-decyloxybenzoyl chloride and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (Example 41). Example 118, compound 73, was prepared from 4-decylbenzoyl chloride and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (Example 41). Example 119, compound 74, was prepared from 3-chloro-4-octyloxybenzoyl chloride (Example 13) and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (Example 41). Example 120, compound 75, 3-methoxy-4-octyloxybenzoyl chloride (Example 12) and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (Example 41). Example 121, compound 76, was prepared from 6-(4-methylhexyloxy)nicotinoyl chloride (Example 34) and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (Example 41). Example 122, compound 77, was prepared from 4-(1,1-dihydroperfluoroethoxy)phenol (Example 24) and 3-chloro-4-(4′-decyloxybenzyloxyl)benzoic acid. Example 123, compound 78, was prepared from 2-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoyl chloride (Example 9) and 4-hydroxyphenyl 4-decylbenzoate (Example 45). Example 124, compound 79, was prepared from 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoyl chloride (Example 6) and 4-hydroxyphenyl 4-decylbenzoate (Example 45). Example 125, compound 80, was prepared from 4-(1,1-dihydroperfluorooctyloxy)benzoic acid (Example 5) and 4-hydroxyphenyl 4-(1,1-dihydroperfluorobutoxy)benzoate (Example 41). Example 126 Hydroquinone (0.55 g, 5 mmol), 4-(1,1-dihydroperfluorobutoxy)benzoic acid (3.20 g, 10.0 mmol, prepared in Example 1), and 4-dimethylaminopyridine (0.10g) were dissolved in 100 mL of methylene chloride. Dicyclohexylcarbodiimide (2.06 g, 10 mmol) was then added all at once. The reaction mixture was stirred at room temperature under nitrogen for 1 day, filtered, and washed successively with about 100 mL 0.5 M HCl, about 100 ml 5% sodium bicarbonate, and about 100 mL water. The separated organic layer was dried over anhydrous MgSO₄, filtered, and the filtrate concentrated under reduced pressure. The crude material was purified by recrystallization from ethanol-toluene to provide 2.62 g (73% yield) of compound 81, Table I, 1,4-bis-(4-(1,1-dihydroperfluorobutoxy)benzoyloxy)benzene, whose structure was confirmed by H- and F-NMR, MS, and IR spectroscopies. Examples 127-131 In Examples 127-131, compounds 82-86 of Table I were prepared as in Example 126 except that the precursor compounds indicated below were substituted for the hydroquinone and 4-(1,1-dihydroperfluorobutoxy)benzoic acid. Example 127, compound 82, was prepared from chlorohydroquinone and 4-(1,1-dihydroperfluorohexyloxy)benzoic acid (Example 4). Example 128, compound 83, was prepared from methylhydroquinone and 4-(1,1-dihydroperfluoropropoxy)-benzoic acid (Example 3). Example 129, compound 84, was prepared from tetrafluorohydroquinone and 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1). Example 130, compound 85, was prepared from 1,4-dihydroxynapthalene and 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1). Example 131, compound 86, was prepared from 2,6-dihydroxynapthalene and 4-(1,1-dihydroperfluorobutoxy)benzoic acid (Example 1). Example 132 Terephthaloyl chloride (1.02 g, 5.0 mmol) in 10 mL anhydrons THF was added dropwise to a solution of 4-(1,1-dihydroperfluoroethoxy)phenol (1.92 g, 10.0 mmol) prepared in Example 24, 2 mL of triethylamine, and 50 mL of anhydrous THF. Upon completion of the addition, the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 1 day, filtered, and the filtrate was concentrated under reduced pressure. The crude residue was recrystallized from toluene-ethanol to provide 2.38 g (93% yield) of compound 87, Table I, bis-(4-(1,1-dihydroperfluoroethoxy)phenyl) terephthalate, whose structure was confirmed by H- and F-NMR, MS, and IR spectroscopies. Examples 133-135 In Examples 133-135, compounds 88-90 of Table I were prepared as in Example 132, except that the precursor compounds indicated below were substituted for the 4-(1,1-dihydroperfluoroethoxy)phenol. Example 133, compound 88, was prepared using 4-(1,1-dihydroperfluoropropoxy)phenol (Example 25). Example 134, compound 89, was prepared using 4-(1,1-dihydroperfluorobutoxy)phenol (Example 20). Example 135, compound 90, was prepared using 4-(1,1-dihydroperfluorohexyloxy)phenol (Example 21). Compounds of Table I were evaluated for transition temperatures by optical observation of material phase changes using a Mettler FP-5 hot stage and a leitz polarizing microscope and/or by standard practice differential scanning calorimetry (DSC) using a perkin elmer model DSC-4. The transition temperatures (°C), upon cooling from the isotropic state (I) to the crystalline state (K), are set forth in Table II. Transitions to and from mesophases other than smectic A (SmA) and smectic C (SmC) are indicated in Table II. The nematic phase is represented by N, smectic B by SmB, smectic E by SmE, and smectic F by SmF. In the following Examples 136-142, liquid crystal electrooptical devices are described which contain the achiral, smectic liquid crystal compounds of the invention alone, mixtures of the achiral, smectic liquid crystal compounds of the invention, and mixtures of the achiral, smectic liquid crystal compounds of the invention with other liquid crystal compounds. For example, mixtures which are smectic C and in which none of the components are chiral are useful in a device application as described by Pelzl, G., Schubert, H., Zaschke, H., and Demus, D., Kristall Technik. , 1979 , vol. 14, 817; Pelzl, G., Kolbe, P., Preukschas, U., Diele, S., and Demus, D., Mol. Cryst. Liq. Cryst. , 1979 , vol. 53, 167; Pelzl, G., Schiller, P., and Demus, D., Liquid Crystals , 1987 , vol. 2, 131; and Schiller, P., Pelzl, G., and Demus, D., Liquid Crystals , 1987 , vol. 2, 21, in which the Freedericksz effect is used. Mixtures which are smectic C and contain a chiral dopant, i.e., a material which is optically active and which is or is not itself a liquid crystal, are ferroelectric and are useful in device applications as described by Clark and Lagerwall in U.S. Patent No. 4,367,924. Mixtures which exhibit a smectic A mesophase are useful in devices described by Crossland, et al. in U.S. Patents No. 4,411,494, No. 4,419,664, and No. 4,528,562. Mixtures which exhibit a smectic A mesophase and contain a chiral component are useful in a device as described by Lagerwall, et al. 1st International Symposium on Ferroelectric Liquid Crystals , Bordeaux-Arcachon, France, 1987. The percentages given for each of the components were determined from normalized gas chromatographs on the mixtures unless otherwise noted. The mesophases were determined by optical microscopy using a Mettler FP-5 hot stage and a Leitz polarizing microscope. The transition temperatures were determined by optical microscopy using the hot stage and polarizing microscope and/or by standard differential scanning calorimetry (DSC) using a Perkin-Elmer Model DSC-4. The response times of the mixtures were measured at the rising edge of the cell photoresponse and calculated from 10-90% of the maximum transmission. The response times were measured at a voltage of 30 and at the temperatures given in each example. The polarizations were determined according to the procedure of Miyasato, et al., Jap. J. Appl. Phys. , vol. 22, 1983, p. 1661-1663, for the mixtures exhibiting a chiral smectic C (smectic C*) mesophase. The tilt angles of the mixtures in the smectic C(*) mesophase were determined by the technique described by Baikalov, et al., Mol. Cryst. Liq. Cryst. , 1985, vol. 127, pp. 397-406. Each cell used in the liquid crystal electooptical display devices was fabricated as follows: Two indium-tin oxide-coated glass substrates (3.49 cm x 2.86 cm, 1.65 mm thick were cleaned with monoethanolamine. An electrode pattern was etched into each indium-tin oxide coating through a photolithography process. The resulting glass substrates had a conductive indium-tin oxide electrode-active area of 0.9073 cm⁻². Onto the indium-tin oxide surface of one of the substrates, a 0.5% nylon in formic acid solution was spun at 1100 r.p.m., the solvent was removed, and the nylon film (about 500 angstroms thick) was buffed with a soft roller brush for 15 minutes. The glass substrates were adhered together with indium-tin oxide surface facing indium-tin oxide surface and mylar spacers (2-4 micrometers thick) located along two opposing edges of the substrates, by a thermally-cured or u.v. -cured epoxy adhesive applied along the edges having the spacers. The cells were then filled with the specified liquid crystal material by capillary action at temperatures above the isotropic to smectic A(*) transition. Example 136 A mixture was prepared by mixing the following: 6-decyloxynicotinic acid 4-(1,1-dihydroperfluorohexyloxy)phenyl ester (Compound 57) 5.14% 4-octyloxybenzoic acid 4-(1,1-dihydroperfluorobutoxy)phenyl ester (Compound 15) 9.36% 4-octyloxybenzoic acid 4-(1,1-dihydroperfluorohexyloxy)phenyl ester (Compound 16) 9.44% 4-(1,1-dihydroperfluorobutoxy)benzoic acid 4-octyloxyphenyl ester (Compound 26) 10.61% 4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 63) 12.42% 4-(4-decyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 64) 30.23% 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid 4-decycloxyphenyl ester (Compound 36) 22.81% The mixture exhibited smectic A and smectic C mesophases. Transition temperatures of the mixture were 87°C for I->SmA, 69°C for SmA->SmC, and at 5°C the mixture made a transition from SmC to an unidentified high order smectic or crystalline phase. Using a field of 10V/µm at 25°C, the mixture had a time on of 15 msec and a time off of 15 msec in the SmC mesophase. Using a field of 15V/µm at 25°C, the mixture had a time on of 13 msec and a time off of 12 msec in the SmC mesophase. Using a field of 20V/µm at 25°C, the mixture had a time on of 11 msec and a time off of 5 msec in the SmC mesophase. Example 137 A mixture was prepared by mixing together the following: A 2.7 micrometers thick cell was filled with this mixture by capillary action. The mixture exhibited chiral smectic A and chiral smectic C mesophases. Transition temperatures of the mixture were 91°C for I->SmA*, 59°C for SmA*->SmC*, and at 2°C the mixture made a transition from SmC* to an unidentified high order chiral smectic or crystalline phase. Using a field of 30V at 20°C, the mixture had a response time of 308 µsec, a polarization of 12.4 nC/cm⁻², and a tilt angle of 29°. Using a field of 30V at 45°C, the mixture had a response time of 41 µsec, a polarization of 7.76 nC/cm⁻², and a tilt angle of 22.8°. Example 138 A mixture was prepared by mixing together the following: 4-octyloxybenzoic acid 4-(1,1-dihydroperfluorobutoxy)phenyl ester (Compound 15) 15.33% 4-(4-octyloxybenzoyloxy)benzoic acid 1-1-dihydroperfluorobutoxy ester (Compound 63) 16.51% 4-(4-decyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 64) 21.08% 2-chloro-4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 42) 9.67% 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid 4-octyloxyphenyl ester (Compound 38) 37.41% The mixture exhibited smectic A and smectic C mesophases. Transition temperatures of the mixture were 88°C for I->SmA, 69°C for SmA->SmC, and at -9°C the mixture made a transition from SmC to an unidentified higher order smectic or crystalline phase. Example 139 A mixture was prepared by mixing together the following: 4-octyloxybenzoic acid 4-(1,1-dihydroperfluorobutoxy)phenyl ester (Compound 15) 14.88% 4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 63) 14.56% 4-(4-decyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 64) 18.29% 2-chloro-4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 42) 11.73% 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid 4-octyloxyphenyl ester (Compound 38) 31.28% S -4-(2-chloro-4-methylpentanoyloxy)phenyl 4-(1,1-dihydroperfluorohexyloxy)benzoate (Prepared as in Example 133 of European Patent Publication No. 0,255,236) 9.27% A 2.7 micrometers thick cell was filled with this mixture by capillary action. The mixture exhibited chiral smectic A and chiral smectic C mesophases. Transition temperatures of the mixture were 85°C for I->SmA*, 65°C for SmA*->SmC*, and at -13°C the mixture made a transition from SmC* to an unidentified high order chiral smectic or crystalline phase. Using a field of 30V at 25°C, the mixture had a response time of 148 µsec, a polarization of 8.9 nC/cm⁻², and a tilt angle of 30.2°. Using a field of 30V at 45°C, the mixture had a response time of 37 µsec and a tilt angle of 30.0°. Example 140 A mixture was prepared by mixing together the following: 4-octyloxybenzoic acid 4-(1,1-dihydroperfluorobutoxy)phenyl ester (Compound 15) 13.36% 4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 63) 13.14% 4-(4-decyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 64) 16.97% 2-chloro-4-(4-octyloxybenzoyloxy)benzoic acid 1,1-dihydroperfluorobutoxy ester (Compound 42) 10.78% 3-chloro-4-(1,1-dihydroperfluorohexyloxy)benzoic acid 4-octyloxyphenyl ester (Compound 38) 28.31% S -4-(2-chloro-4-methylpentanoyloxy)phenyl 4-(1,1-dihydroperfluorohexyloxy)benzoate (Prepared as in Example 133 of European Patent Publication No. 0,255,236) 17.44% A 2.7 micrometers thick cell was filled with this mixture by capillary action. The mixture exhibited chiral smectic A and chiral smectic C mesophases. Transition temperatures of the mixture were 83°C for I->SmA*, 61°C for SmA*->SmC*, and at -13°C the mixture made a transition from SmC* to an unidentified high order chiral smectic or crystalline phase. Using a field of 30V at 25°C, the mixture had a response time of 81 µsec, a polarization of 26.0 nC/cm⁻², and a tilt angle of 34.5°. Using a field of 30V at 45°C, the mixture had a response time of 19 µsec and a tilt angle of 32.0°. Example 141 A mixture was prepared by mixing together the following: A 2.9 micrometers thick cell was filled with this mixture by capillary action. The mixture exhibited chiral smectic A and chiral smectic C mesophases. Transition temperatures of the mixture were 87°C for I->SmA*, 68°C for SmA*->SmC*, and at 2°C the mixture made a transition from SmC* to an unidentified high order chiral smectic or crystalline phase. Using a field of 30V/um at 25°C, the mixture had a response time of 250 µsec and a polarization of >1 nC/cm⁻². Example 142 A mixture was prepared by mixing together the following: A 2.8 micrometers thick cell was filled with this mixture by capillary action. The mixture exhibited chiral smectic A and chiral smectic C mesophases. Transition temperatures of the mixtures were 80°C for I->SmA*, 63°C for SmA*->SmC*, and at 2°C the mixture made a transition from SmC* to an unidentified high order chiral smectic or crystalline phase. Using a field of 30V at 35°C, the mixture had a response time of 40 µsec, a polarization of 22.9 nC/cm⁻², and a tilt angle of 30.6°. In the following Tables III-IX, comparisons are made of the mesophases exhibited by selected compounds of the invention and the hydrocarbon analogs. The mesophases for the hydrocarbon analogs were obtained from Demus, Demus, and Zaschke, Flussige Kristalle in Tabellen , VEB Deutscher Verlag fur Grundstoffindustrie, Leipzig, 1974, and Demus and Zaschke, Flussige Kristalle in Tabellen II , VEB Deutscher Verlag fur Grundstoffindustrie, Leipzig, 1984. The compounds of Table III can be represented by the formula where R, R', and X are as set forth in the table. The compound numbers are also set forth in Table III for the compounds of the invention. The compounds of Table IV can be represented by the formula where R is as set forth in the table. The compound numbers are also set forth in Table IV for the compounds of the invention. R Cmpd No. Mesophases C₄H₉- - N C₃F₇CH₂- 89 SmA, SmC C₆H₁₃- - N C₅F₁₁CH₂- 90 SmA, SmC The compounds of Table V can be represented by the formula where R is as set forth in Table V. The compound numbers are also set forth in Table V for the compounds of the invention. R Cmpd No. Mesophases C₄H₉ - N C₃F₇CH₂ 85 SmA The compounds of Table VI can be represented by the formula where R, R', and X are as set forth in the table. The compound numbers are also set forth in Table VI for the compounds of the invention. R R' X Cmpd No. Mesophases C₄H₉- -OC₄H₉ H - N C₃F₇CH₂- -OCH₂C₃F₇ H 81 SmA, SmC C₄H₉- -OC₈H₁₇ H - N C₃F₇CH₂- -OC₈H₁₇ H 71 N, SmA, SmC C₃F₇CH₂- -OCH₂C₇F₁₅ H 80 SmA, SmC C₄H₉- -C₁₀H₂₁ H - N C₃F₇CH₂- -C₁₀H₂₁ H 73 SmA, SmC C₃H₇- -OC₃H₇ CH₃ - N C₂F₅CH₂- -OCH₂C₂F₅ CH₃ 83 SmA C₆H₁₃- -OC₆H₁₃ Cl - N C₅F₁₁CH₂- -OCH₂C₅F₁₁ Cl 82 SmA, SmC The compounds of Table VII can be represented by the formula where R is as set forth in Table VII. The compound number is also set forth in Table VII for the compound of the invention. R Cmpd No. Mesophases C₆H₁₃- - N C₅F₁₁CH₂- 50 SmA, SmB The compounds of Table VIII can be represented by the formula where R is as set forth in Table VIII. The compound number is also set forth in Table VIII for the compound of the invention. R Cmpd No. Mesophases C₆H₁₃- - N, SmA, SmC C₅F₁₁CH₂- 48 SmA, SmC The compounds of Table IX can be represented by the formula where R is as set forth in the table. The compound numbers are also set forth in Table IX for the compounds of the invention. Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the following illustrative embodiments set forth herein.

Claims: Achiral fluorine-containing liquid crystal compounds comprising a fluorocarbon terminal portion which can be represented by the formula -DC q F 2q+1 where q is 1-20, and D is -O-(CH₂) r -, -(CH₂) r -, OSO₂-, -SO₂-, -SO₂(CH₂) r -, -O(CH₂) r -O(CH₂) r' -, or where r and r' are independently 1 to 20 and p is 0 to 4, and a hydrocarbon or another fluorocarbon terminal portion, the terminal portions being connected by a central core, the compounds having smectic mesophases or having latent smectic mesophases. The compounds of claim 1 wherein said central core comprises at least two aromatic, heteroaromatic, cycloaliphatic, or substituted aromatic, heteroaromatic, or cycloaliphatic rings. The compounds of claim 2 wherein rings are connected one with another by -COO-, -COS-, -HC=N-, or -COSe-. The compounds of claim 1 wherein said compounds can be represented by the general formula I: where M, N, and P are each independently a, b, and c are independently zero or an integer of from 1 to 3 with the proviso that the sum of a + b + c be at least 2; each A and B are non-directionally and each independently nil, -CH₂CH₂-, -CH=CH-, -C≡C-, -CH=N-, -CH₂-O-, -CO- or -O-; each X, Y, and Z are independently -H, -Cl, -F, -Br, -I, -OH, -OCH₃, -CH₃, -CN, or -NO₂; each l, m, and n are independently zero or an integer of 1 to 4, D is -O-(CH₂) r -, -(CH₂) r -, -OSO₂-, -SO₂-, -SO₂-(CH₂) r -, -O(CH₂) r -O-(CH₂) r' -, or where r and r' are independently 1 to 20, and p is 0 to 4; R is -O-C q H 2q -O-C q' H 2q'+1 , -C q H 2q -O-C q' H 2q'+1 , -C q H 2q -R', -O-C q H 2q -R', or where R' is -Cl, -F, -CF₃, -NO₂, -CN, -H, or and q and q' are independently 1 to 20, and R can be straight chain or branched, and R f is C q F 2q+1 where q and q' are independently 1 to 20. Mixtures of two or more of the compounds of claim 1, at least one of said compounds having smectic mesophases. Liquid crystal mixtures comprising at least one compound according to claim 1 and at least one chiral liquid crystal compound, said chiral liquid crystal compound being present in an amount sufficient to provide the mixture with ferroelectric properties. Liquid crystal mixtures comprising at least one compound according to claim 1 and at least one non-liquid crystal compound, said non-liquid crystal compound being present in an amount sufficient to provide the mixture with ferroelectric properties. A liquid crystal display device containing said compound of claim 1 wherein said compound has a smectic mesophase. A process for preparing achiral fluorine-containing liquid crystal compounds of claim 1 comprising the steps of (1) mixing at least one compound represented by the formula with at least one compound represented by the formula or (2) mixing at least one compound represented by the formula with at least one compound represented by the formula where M, N, and P are each independently a, b, and c are each independently zero or an integer of from 1 to 3 with the proviso that the sum of a+b+c be at least 2; each A and B are independently nil, -CH=N-, CH₂-O-, or -O-, -CH₂CH₂-, -CH=CH-, or -C≡C-; each A', A'', B', and B'' are independently -OH, -COOH, -CH(CH₂OH)₂, -SH, -SeH, -TeH, -NH₂, -COCl, -CHO, or -CH₂COOH with the proviso that A' can enter into an addition or condensation reaction with A'' and B' can enter into an addition or condensation reaction with B''; each X, Y, and Z are independently -H, -Cl, -F, -OCH₃, -OH, -CH₃, -NO₂, -Br, -I, or -CN; each l, m, and n are independently zero or an integer of 1 to 4; R is OC q H 2q -OC q' H 2q'+1' -C q H 2q -O-C q ,H 2q'+1 , -C q H 2q -R', -O-C q H 2q -R', or where R' is -H, -Cl, -F, -CF₃, -NO₂, -CN, or and q and q' are independently 1 to 20; D is -O-(CH₂) r -, -(CH₂) r -, OSO₂-, -SO₂-, -SO₂-(CH₂) r -, -O(CH₂) r -O(CH₂) r' -, or where r and r' are independently 1 to 20, and p is 0 to 4; R f is -C q F 2q+1 where q and q' are independently 1 to 20; and allowing said A' and A'' or B' and B'' to react in the presence of suitable coupling agents.

Inventors: JANULIS EUGENE P, JANULIS, EUGENE P.
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 1989
Main classification: C07C69
IPC codes: C07D213, C09K19, C07C43, C07C69, C07D319, C07C255, C07C327, C07C45, C07C65, C07D239, G02F1, C07C47