FR2622595A1 - FERROELECTRIC LIQUID CRYSTAL HAVING ATTACHED FLUORINE ATOM HAS AN ASYMMETRIC CARBON ATOM - Google Patents

Abstract

The present invention relates to a ferroelectric liquid crystal consisting of a biphenyl ester compound having a fluorine atom attached to an asymmetric carbon atom; more particularly, this ferroelectric liquid crystal has the following structural formula: (CF DRAWING IN BOPI) in which n is an integer from 6 to 20 and m is an integer from 3 to 20. This liquid crystal consists of a single liquid crystal and exhibits a high value of spontaneous polarization and high chemical stability.

Description

BACKGROUND OF THE INVENTION

Field of the invention

  The present invention relates to a ferro-liquid crystal

  An electrolyte containing a biphenyl ester compound having a fluorine atom attached to an asymmetric carbon atom.

DESCRIPTION OF THE PRIOR ART

  A ferroelectric liquid crystal is characterized by

  high speed response and bistable memory performance.

  It can be used as a raw material for crimp elements

  liquid rates at high speed because of these characteristics. The

  The response time (T) of a ferroelectric liquid crystal is

  to the value of the spontaneous polarization as can be seen from the following approximation formula: T = n / Ps: E where Ps is the spontaneous polarization, n is the viscosity

and E is the electric field.

  For a ferroelectric liquid crystal to have a

  response time, it must have a high value of Ps.

  however, in practice, a desired liquid crystal is prepared by mixing various types of liquid crystals to satisfy the conditions

  following requirements that no single liquid crystal can satisfy.

  (1) It must operate over a wide temperature range at

  neighborhood of the ambient temperature.

  (2) It must have a structure such that the smectic phase has a

not helicoidal enough long.

  (3) It must allow easy control of orientation.

  (4) It must have a low viscosity.

  In the case where the desired liquid crystal is prepared by mixing different types of liquid crystals, it has the defect that the spontaneous polarization value (Ps) decreases in a

great extent.

SUMMARY OF THE INVENTION

  The present invention provides a ferro-liquid crystal

  which consists of a single liquid crystal and which still has a high value of spontaneous polarization and stability

high chemical

  The present invention provides a ferro-liquid crystal

  based on a biphenyl ester compound having an atom of

  fluorine attached to an asymmetric carbon atom.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS

  The ferroelectric crystal of the present invention is characterized by having a fluorine atom attached to an atom

  asymmetric carbon, as shown in the following structural formula:

  vante: F o Hn + C OCCHC H + nII * m 2m + l where n is an integer from 6 to 20 and m is a number

integer from 3 to 20.

  For a liquid crystal to have a high value of spontaneous polarization (Ps), it must satisfy the following requirements:

  (1) The dipole moment must be large in the direction perpendicular

to the molecule.

  (2) The permanent dipole must be close to the benzene ring.

  (3) The asymmetric carbon atom must be close to the dipole

  nent. In accordance with the present invention, these required conditions are satisfied when a fluorine atom which has high electronegativity is attached to an asymmetric carbon atom adjacent to the carbonyl group near the benzene ring. The fluorine atom increases the dipole moment and thus increases the spontaneous polarization (Ps). In addition, the liquid crystal thus obtained is stable

  because the C-F bond is chemically stable.

EXAMPLES

  The raw material for producing the ferroelectric liquid crystal has a fluorine atom attached to a carbon atom

  asymmetrically and is an optically active carboxylic acid corresponding

  laying down the desired liquid crystal. It is synthesized from an optically active amino acid or a chiral epoxide by one

of the following three methods.

Process A

NH2 -F

NH HF / pyridine

I I

  2m + 2m + 1m NaNO 2m + 1m.n Amino acid 2 Method B NH2 Nm1mH2 NaNO2 C2H50H

H C2CHCOOH

  ammonia * aqueous CH3COOH H + amino acid OH

H 1C (CF 3 SO 2) 20

H'm + C CHCOOC2H ...

2m + 1m OC25

0S02CF3

1 nBuoN (F H2m + 1CmCHCOOC2H5 n-Bu4N F

F F

H NaOH 1 CHCOOH

H2 CHCOOC H H C CHCOOH

  20. 2m m 25 m m Method C CmH2m + 1H HF / pyridine HOH2C-C2 * HOH2C; C-CmH2m + 1 F Chiral epoxide H KMnO4 I 4> HOOC-C -CmH2m + 1

F

  The configuration of the fluorinated carboxylic acid obtained by Method C is not yet completely determined, since it is not known whether the opening of the epoxide ring leads to retention or inversion, but the absolute configuration of The chiral epoxide is known. In contrast, the fluorinated carboxylic acids obtained by process A and process B differ from each other in their configuration. In other words, the product obtained by the process

  A has a configuration (S) because the asymmetric portion of an L-amino

  acid retains its configuration (S). The product obtained by process B has the configuration (R) because the reaction carried out involves an inversion. The reaction products obtained by process A and

  process B are not enantiomers but are diastereoisomeric

  mothers. The product obtained from L-isoleucine which has the

  figuration (2S, 3S) by method A, has the configuration (2S, 3S) and the product obtained from L-isoleucine by method B has the configuration (2R, 3S). Fluorocarboxylic acid

  thus obtained is converted into a ferroelectric liquid crystal

according to the following method.

F F

I SOCL2

  H.C CHCOOH - H C CHCOCl + 2m4 m, 2m + 1 m, * H2n + 1CnO O-O-OH '+ F

OCCHC H +

  H2n + 1CnO- - - m -2m + o Example 1 (Synthesis by Method A) F CH3 (2S, 3S) -n-H17C8O-O-O -OCOCHCHC2H5 In 50 ml of a 70% solution of HF in pyridine, 20 g of L-isoleucine are dissolved. To this solution is added slowly 16 g of dry sodium nitrite under cooling with ice and stirring. The solution is stirred for another hour at

  Room temperature. The solution is diluted with water containing

  ice and then extracted with ether. The extract is washed with a 5% aqueous solution of NaHCO 3. After drying over MgSO4, the extract is freed from ether by distillation. To the residue (4 g) an excess of thionyl chloride and dichloride is added.

  romethane to form an acid chloride (2.5 g) in the usual manner.

  tual. The acid chloride is reacted in benzene with

  the n-octyl ether of p, p'-biphenyldiol in the presence of triethyl

  amine to provide the desired liquid crystal compound having the

  following characteristic properties.

  Specific Rotation [a] +0.7 (C = 1, ethanol) 1H-NMR (CDCl3) δ 4.72 (d), 5.64 (d), (CH-F, JHH = 3 Hz) Mass (M +) 414 Incidentally, 1 H-NMR data give peaks resulting from impurities in the neighborhood of b = 5.9 and 5.95 ppm, and mass data give a peak at m / e of 394. This suggests that the product contains the following compound formed by removal of HF.

CH3

  I n-H1 7C80-O-OCOCH = C-C2H5 The desired liquid crystal compound exhibits polarization

  spontaneous at 57.6 to 73 C measured by the triangular wave method.

  The spontaneous polarization reaches the maximum value of 112 nC / cm3

  at 61 C (measured at a frequency of 50 Hz).

  EXAMPLE 2 (Synthesis by Method B) F CH3 (2R, 3S) -N-H25C120-1OCOCHCHC2H5 In 200 ml of a 50% aqueous solution of acetic acid, 20 g of L-isoleucine are dissolved. To this solution we add drop

  30 ml of an aqueous solution of NaNO2 (21 g) under cooling

  defrosting by ice. This solution is stirred again during

  I hour at room temperature. The solution is extracted with ether.

  The extract is freed from ether by distillation. To the residue, 0.5 g of toluenesulphonic acid, 300 ml of ethanol and 100 ml of benzene are added. The solution is heated to reflux. During reflux, the water is separated as an azeotrope with ethyl acetate, benzene and ethanol. After 12 hours, the solution is extracted with ether and the extract is washed and dried. After distillation under

  reduced pressure, 15.9 g of 2-hydroxy-3-methyl-

  ethyl pentanoate (boiling point: 67-70 ° C / 2 mmHg). This ester (11 g) is dissolved together with 8 ml of lutidine in 20 ml of dichloromethane. To the resulting solution, 15.4 ml of trifluoromethanesulfonic acid anhydride are added dropwise under cooling with ice, followed by stirring for 0.5 hours. The solution is then passed through a short column of silica gel and then subjected to pressure distillation.

  scaled down. 17.7 g of 2- (trifluoromethanesulfonyloxy) 3 are obtained.

  ethyl methylpentanoate (boiling point: 71-75 ° C / 2 mmHg).

  This ester (17.7 g) is dissolved in 150 ml of acetonitrile and

  solution, 18 g of tetra (n-butyl) fluoride trihydrate are added

  ammonium, then allowed to stand overnight at 5 C. The resulting solution was passed through a short column of silica gel and subjected to distillation under reduced pressure. 6.1 g of ethyl 2-fluoro-3-methylpentanoate (boiling point: -74 ° C / 2 mmHg) are obtained. This compound is added to 150 ml of NAOH-1N and the

  The solution is stirred at room temperature for 12 hours.

  After neutralization with dilute hydrochloric acid, the solution is extracted with ether and the extract is dried and freed of ether by distillation under reduced pressure. About 4 g of 2-fluoro-3-methylpentanoic acid are obtained. The compound is converted to an acid chloride (about 3 g) in the usual manner. The acid chloride is reacted with the mono-n-dodecyl ether of p, p'-biphenyldiol to give the desired liquid crystal compound which

  has the following characteristic properties.

  Specific Rotary Power [] + 1.1 (C = 1, CHCl 3) 1 H-NMR (CDCl 3) δ 4.70 (d), 5.52 (d), (CH-F) Mass (M +) 470 Incidentally, the following compound is synthesized by the

  method B in the same manner as described above.

  F CH3 I I n -H17C8O-- o-o _OCOCHCHC25 *

  This compound has the following properties.

  Specific Rotation Potency 20 - 1.3 (C = 1, ethanol, + 1.10 (C 1, CHCl 3) 1H-NMR (CDCL 3) b 4.60 (d), 5.40 (d), (CH-F , JHH = 4.8 Hz) It should be noted that this compound differs from that obtained in Example I with regard to the chemical shift.

  The NMR data of this compound do not show peaks resulting from

  observed in Example 1. This suggests that

  poses obtained by process A and process B have the same structural formulas but are diastereoisomers having

  different chemical and physical

  The liquid crystal compound exhibits a spontaneous polarization

  at 72 to 80 C, which reaches a maximum value of 200 nC / cm3 and 188 nC / cm at 76.6 C (measured at frequencies of 3 Hz and 50 Hz, respectively). EXAMPLE 3 (Synthesis by Method C) F n -H17C80--OCCH (CH) CH3

o.

  To 80 ml of a 70% solution of HF in ice-cold pyridine is added dropwise with stirring.

  ml of an ether solution containing 9.15 g of (R) -1,2-epoxy-

  octane. The reaction is conducted under cooling with

  ice for 1 hour then at room temperature for 1 hour.

  The reaction liquid is neutralized with a% NaHCO 3 aqueous solution. The ether layer is separated and dried with MgSO4 and freed of the solvent by distillation under reduced pressure (65 C, 0.3 mmHg). 6.1 g of 2-fluorooctanol (yield

58%).

  2-Fluorooctanol is dissolved together with 10 g of

  NaOH in 200 ml of water. To the resulting solution, slowly add

  10. with stirring KMnO4 powder in an amount of about 17 g.

  The solution is stirred at room temperature for 1 hour and then heated to 50-60 ° C, and the reaction is continued for about -6 hours until the supernatant becomes clear. The reaction liquid is filtered to remove the MnO 2, and then washed 3 to 4 times with hot water. The filtrate is extracted with ether to remove the crude alcohol. The aqueous layer is neutralized with dilute hydrochloric acid and the diluted solution is extracted

  with ether. The extract is dried and freed of ether by distillation.

  under reduced pressure. 2.15 g (yield: 32%) of 2-fluorooctanoic acid (boiling point: 70-100 ° C / 0.3 ° C.) are obtained.

0.4 mmHg).

  This compound is converted to acid chloride in the way

  usual and the acid chloride is reacted with the mono ether

  n-octyl of p, p'-biphenyldiol, to give the crystal compound

  desired liquid having the following properties.

  Rotatory specificity Ca [D + 0.3 (C = 1, CHCl)

D 3

  1 H-NMR (CDCl 3) δ 4.72 (t), 5.56 (t), (CH-F) Mass (M +) 442

  The liquid crystal compound exhibits a spontaneous polarization

  at 104.8 to 98.3 C, which reaches the maximum value of 192 nC / cm3

  at 102.5 C (measured at a frequency of 50 Hz).

  - The processes mentioned previously can also

  to be used to produce compounds having a molecular

  other than the biphenyl group. The present invention provides a stable ferroelectric liquid crystal having a high value of spontaneous polarization (Ps). Because of this property, it can be mixed with various liquid crystal compounds to give

  compositions for practical use which have a desired value of polarity.

  spontaneous and high speed response. In addition, the crystal

  Ferroelectric liquid finds its application as an electroelectric element

  optical because its smectic phase responds to electric fields.

  This element has a higher speed response than the elements

  TN type liquid crystal. Moreover, we can give him a

  memory when its orientation is appropriately controlled. Because of these features, the ferroelectric liquid crystal of the present invention can be applied to high speed optical shutters and display units which

  have a lot of information.

  It is obvious that various modifications can be made to the embodiments described without departing from the scope of the present invention.

present invention.

Claims (3)

  1. A ferroelectric liquid crystal, characterized in that it corresponds to the following structural formula in which a fluorine atom is attached to an asymmetric carbon atom: F H2n + 1 CnO (/ k -O CCHC H2 1 2n + ln It * * m where n is an integer from 6 to 20 and m is a number integer from 3 to 20.   2. A ferroelectric liquid crystal according to the   cation 1, characterized in that n is equal to 8 and m is equal to 4.   3. A ferroelectric liquid crystal according to the   cation 1, characterized in that n is 8 and m is 6.