CH622245A5 - Process for the preparation of p-cyanophenyl 4-alkyl-4'-biphenylcarboxylates, and the use thereof in liquid-crystal substances - Google Patents

Description

The present invention relates to the production of new organic compounds and the use thereof in liquid crystal compounds. In particular, it relates to: the production and use of new organ compounds which, in the state of a liquid crystal, have a positive dielectric anisotropy at temperatures around the melting point or higher. Nematic liquid crystals with a positive dielectric anisotropy are used for display devices, an electrical field effect being produced by voltage in a liquid crystal cell with a rotating configuration.

Organ compounds for liquid crystal display devices must be in a nematic state. Accordingly, in order that liquid crystal display devices can be used at natural room temperature without being equipped with a special thermostat device, it is practically necessary that the nematic temperature range for liquid crystal substances is wide. However, there is not a single connection that meets this requirement. In practice, therefore, substances are selected that consist of several compounds. Furthermore, it is necessary for each individual compound from which liquid crystal materials with a large temperature range are composed that the individual compounds already have a suitable temperature range and the largest possible nematic temperature range.

In general, the nematic temperature fluctuation range of a single connection is a relatively large width of approximately 50 ° C. A width of 100 ° C. can already be regarded as exceptional. Examples of connections with such an extraordinarily large nematic temperature fluctuation range are the following or the same similar connections:

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

3rd

622 245

en »(ch2) 5 ~ o - ^^ - c-o - ^^ - o-a- ^ y-o- (CH2) 5-ch3

Cl

78-175 °

CH3 (cii2) 5-O-Q-C-O-0-O-C-0-O- (Cii2) 5-ai3

120-205 °

n ~ C8H17 ~ ° ~ ^^ ~ CII ~ N ~ ^ 3 ~ N = CH ~ C $> '* 0 ~ C8H; L7

cf

59-179 °

These compounds have a negative dielectric anisotropy and cannot be used for the above-mentioned electrical field principle display devices. With regard to compounds with positive dielectric anisotropy with a simultaneous nematic temperature fluctuation range, comparable to the compounds mentioned above, only 4-n-pentyl-4 "cyanoterphenyl (130-239 °) and 4-n- Heptyl-4 "cyanoterphenyl (134-222 °) is reported.

The inventors have searched for compounds with a wide range of nematic temperature fluctuations which can be used for the above-mentioned applications and at the same time have positive-dielectric anisotropy. The result of the research was initially a group of compounds which can be represented by the following formula (I) and which differ completely from the above-mentioned terphenyls:

No-

-COO

CN

(X)

(R «c4-c8)

These compounds are completely new and can be converted into a smectic crystal state by converting 4-n-alkyl-4'-biphenylcarboxylic acids (represented by Formula II shown below) (which are also novel compounds, but unfortunately do not belong to the nematic liquid crystals have) in 4-cyanophenol esters of these compounds by a known reaction process. The 4-n-alkyl-4'-biphenylcarboxylic acids mentioned can be obtained by acidic or alkaline hydrolysis of 4-n-alkyl-4'-cyanobiphenyls (represented by the formula III given below) or by the method described by us in Japanese Patent Application No. 44496/1975, ie by oxidation of 4-alkyl-4'-azetbiphenyl.

n-R- ^ J - ^ - COOII (R = "C4-Cg) (II) n-R - ^ - Q-CN (R = C4-C8) (III)

As is apparent from the above, the object of this invention is to enable the production of a novel nematic liquid crystal compound which is simple, has a wide range of temperature fluctuations and has a positive dielectric anisotropy, starting from substances of the type described above.

The solutions according to the invention are summarized below:

1. A process for the production of p-cyanophenyl-4-alkyl-4'-biphenylcarboxylates, in which the said alkyl is an alkyl group in a linear chain with 4-8 carbon atoms,

or an alkyl group in a branched chain with 5-7 carbon atoms with the methyl group in a branched chain, the

25 is characterized by the condensation of a 4-alkyl-4'-biphenylcarboxylic acid (in which the said alkyl has the same meaning as given above) with p-cyanophenol;

2. A method for producing p-cyanophenyl-4-alkyl-4'-biphenylcarboxylates according to the above-cited statement (1),

30 wherein said 4-alkyl-4'-biphenylcarboxylic acid is obtained by the hydrolysis of 4-alkyl-4'-cyanobiphenylene, wherein said alkyl has the same meaning as that stated in (1) with an acid or an alkali;

3. A method for producing p-cyanophenyl-4-Al-

35 kyl-4'-biphenyl carboxylates according to the above (1),

wherein said 4-alkyl-4'-biphenylcarboxylic acid by oxidation of 4-alkyl-4'-acetylbiphenylene, wherein said alkyl has the same meaning as defined above;

4. Use of one or more types of p-cy-

40 anophenyl-4-alkyl-4'-biphenyl carboxylates as defined in section (1, 2 or 3) in a liquid crystal substance.

Furthermore, the following combinations of substances can preferably be used in liquid crystal substances:

5. A mixture of (i) p-cyanophenyl-4-alkyl-4'-biphe-

45 nylcarboxylates as defined in section (1), and (ii)

4-alkyl-4'-cyanobiphenyl and / or 4-alkoxy-4'-cyanobiphenyl;

6. A mixture of (i) p-cyanophenyl-4-alkyl-4'-biphenylcarboxylate according to section (1), (ii) 4-alkyl-4'-cyanobi-

50 phenyl, (iii) 4-alkoxy-4'-cyanobiphenyl and (iv) 4-cyano-4 "-n-pentylterphenyl and / or 4-cyano-4" -n-hexylterphenyl; and

7. A mixture with the following 4 groups of (A) - (D), except p-cyanophenyl-4-alkyl-4'-biphenyl carboxylate:

55 (A) two or three types of compounds selected from the group consisting of 4-alkylbenzoic acid-4'-cyanophenyl esters according to the general formula k-O -COO - / \> - CN (IV)

wherein R is the alkyl group in a linear chain with 4-8 carbon atoms or a linear alkoxy group chain with 5-8 carbon atoms, said two types or at least two of the three types of compounds mentioned, each with “R” as a linear alkyl group chain,

(B)

c5HirO-Oa '

60

65

622 245

4th

alone or with a mixture of them

C7H15 ~ 0> 'Ö "CN'

selected from 4-alkyl-4'-cyanobiphenylene expressed by the general formula

C "" 2n + 1-O-0-CN

where n is 5 or 7,

(C) one or two kinds or more of compounds selected from a group consisting of 4-alkylbiphenyl-carboxylic acid-4'-cyanophenylene, expressed by the general formula

S> H2n + l- € K> C0 ° -G-CN (VI)

wherein CnH2n + i is a linear alkyl group chain with 4-8 carbon atoms or a branched alkyl group chain with 5-7 carbon atoms and a methyl group as branched group, and

(D) one or more compounds selected from a group consisting of 4-n-butylbenzoic acid 4'-alkylphenyl esters (where R is the n-heptyl group, n-hexyloxy group or n-heptyloxy group), expressed by the general formula n- ßu - ^^ - COO - ^ - R (VII)

or 4-anisic acid 4'-n-pentylphenyl ester with the formula

CH30-Q-C00-0-C5nil alone or in a mixture with said one or more compounds selected from the group consisting of 4'-n-butylbenzoic acid 4'-alkylphenyl esters.

The above-mentioned 4-alkyl-4'-biphenylcarboxylic acids (wherein the alkyl group is a linear alkyl group chain with 4-8 carbon atoms or a branched alkyl group chain with 5-7 carbon atoms and a methyl group as a branched chain) for use in liquid crystals are preferably acidic as mentioned above or alkaline hydrolysis of 4-alkyl-4'-cyanobiphenyls or by the oxidation of 4-alkyl-4'-acetylbiphenyls. With respect to the p-cyanophenol used for this invention, those obtained by the known manufacturing methods or those obtainable by purification of commercial products can be used.

For example, the reaction procedure is as follows:

4-n-alkyl-4'-cyanobiphenyl is dissolved in sulfuric acid (concentration: 60-80%) in a ratio of about several times up to ten times the substance to be dissolved, the resulting solution is stirred with reflux (temperature: about 140 - 180 ° C) heated. The time required for this is about 1 to 4 hours after the temperature has risen; 4-n-Alkyl-4'-cyanobiphenyl is hydrolyzed to 4-n-alkyl-4'-biphenylcarboxy-20 acid. When the reaction is complete, the resulting reaction product is cooled to room temperature, diluted with water to approximately the same extent as the reaction product and filtered with a glass filter or similar device. The resulting filtered product is recrystallized with a suitable solvent such as acetic acid, resulting in a purified product of 4-n-alkyl-4'-biphenylcarboxylic acid, which is a colorless crystal with a melting point of 150 ° C or higher (depending on the number of carbon atoms in the n-alkyl group (30 pe) and gives a smectic liquid crystal at temperatures of the melting point or higher.

4-n-Alkyl-4'-biphenylcarboxylic acid can also be produced by the above-mentioned method 3 (Japanese Patent Application No. 44496/1975). Thus, as described below in the 35 following formulas (1), the alkylbiphenylcarboxy acid (II) can be prepared from the starting point of the biphenyl, which is an inexpensive, commercially available raw material. A p-cyanophenyl ester (I) can then be prepared therefrom (II).

first stage ^ R-CO ^ Q-Q ^ 1 ^ stage> R-CH2- £) - @ third stage ^ R. GH2-0-0-COCIl3 fourth stage>

* -CH2-O-O-œ0Hfanfte 5tUt °> «.cvO-O ^ -O-«

- (1)

In the above formulas (1), the first stage of the process proceeds according to the conventional Friedel-Krafts reaction. A so-called Friedel-Krafts catalyst such as anhydrous aluminum chloride can be used as the catalyst, and nitrobenzene or carbon disulfide or solvents with similar effectiveness for the process can be used as the reaction solvent. An appropriate acid chloride or a similar compound is used as the alkylating agent.

The physical properties and the yield of 4-alkyl-biphenyls which result in the first stage of the reaction by the above or other method are listed in Table 1. All the compounds described in the table are recrystallized raw materials with methanol or iso-propanol.

5

622 245

Table 1

Physical properties and yield of acylated biphenyls

R.CO-? V

No. R in side chain

Melting point (° C) 3

Yield (%)

©

©

0 ©

©

©

©

©

©

Note:

1 L.M. Long, H.R. Henze, Journal of the American Chemical Society 1963, 1939 (1941).

2 The causes of the value differences in the literature are unclear.

1 The numerical values within the brackets show those from the literature references.

c-c-c-

C-C-C-C-C-C-C-C-C-

c-c-c-c-c-c-

C-C-C-C-C-C-C-C-C-C-C-

I.

c

C-C-C-C-I

c

C-C-C-C-

I.

c

C-C-C-

I.

c

95.9-96.3 (94) 79-79.5 (76-78) 95-96 (96.5) 86-86.5 (86.5-86.5) 99.4-100.0 39 (64) 1.2

b.p. 172-5 (1 mmHg) 57-58

70-72 (71-72.5) 74-75.5 (74.0-76.5)

94

95 95 94 93 91

72

71

65

The course of the reaction in the second stage in the formulas (1) of this invention given above can be carried out simply by the Wolff-Kishner reaction modified by Hung-Minlon, but it can also be carried out by the known catalytic reduction method. The physical properties and the yield of the 4-alkylbiphenyls, which result from the course of the reaction in the second stage, are listed in Table 2.

Table 2 (continued) Physical properties and yield of 4-alkylbiphenylene

H-cvO-O

Boiling point (° C / mmHg)

Yield (%)

No.

R in side chain

45

Table 2

Physical properties and yield of 4-alkylbiphenylene a-cvQ-0

Boiling point yield CC / mmHg) (%)

©

©

C-C-C-C-

I.

c c-c-c-c-I

c

C-C-C-

165-170 / 2 70

160-165 / 2 81

156-157 / 6 82

No.

R in side chain

©

c-c-c-

160-

-164/6

68

> i

©

c-c-c-c-

166-

-167/6

70

©

C-C-C-C-C-

144-

-147/1

79

60 The course of the reaction of the third stage in the above

N_ /

given formulas (1) of this invention corresponds to be

©

C-C-C-C-C-C-

168-

-172/3

80

knew the acetylation reaction according to the Friedel-Krafts React

tion and can be carried out according to a similar procedure

©

C-C-C-C-C-C-C-

181-

-182 / 1.5

82

by using the Appa- known from the first procedure

65 advice is reused. The physical properties

©

C-C-C-C-

140-

-145/1

76

and yield of the acetylated alkylbiphenyls, which can

1

the method of the present invention are disclosed in

c

Table 3 listed.

622 245

6

Table 3

Physical properties and yield of 4'-acetyl-4-alkylbiphenylene

R-CH2-0-Q-COCH3 (• he "" "" "A ™ b '°' e '

No.

0 ©

© © © © © ©

©

R in side chain c-c-c-

C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-C-c-c-c-c-

C-C-C-C-

I.

c

C-C-C-C-

c

C-C-C-

I.

c

87-90

81-82

81-83

81-83

84.2-84.9

47.4 ^ 8.4

79.5-82

74-76

94-96

(%)

85 84 84 70 87 58

69

69

80

10th

15

20th

Table 4

Physical properties and yield of 4'-alkyl-4-biphenylcarboxylic acids

R * CH2-Q> - (3-cooh rc)

Melting point yield (%)

No.

© © © © © © © ©

25th

©

R in side chains

C-C-C-C-

I.

c

C-C-C-C-

i c

C-C-C-C-

I.

c

C-C-C-

199 74

177 84

170-171 75

163 77

151 76.5

204.7-206.1 68

205.2-208.2 66

185-187 76

225.5-227.6 72

The fourth step of the reaction in the above formulas (1) of this invention corresponds to an oxidation reaction with bromine in the medium of alkali and generally belongs to a haloform reaction. In this reaction, the target product can be produced with a good yield if the reaction proceeds at 35-40 ° C and a water-soluble solvent such as. B. p-dioxane with 14-20 gram molecules of sodium hydroxide and 3.3-5 gram molecules, preferably 3.5-4.0 gram molecules, bromine per gram molecule of the acetylated product is used as starting material. The physical properties and the yield of the alkyl-biphenylcarboxylic acids which were produced by this method of the present invention are shown in Table 4 (see Example 10 given below).

All of these compounds show a smectic state at their melting points or at higher temperatures. In the compounds 1-5 shown in Table 4, when the compounds mentioned were mixed with the corresponding substances and when measured, their melting points were found to be in accordance with the method described in Japanese Patent Application No. 116938/1974 [and corresponding to the first representation mentioned above ( 1) of the present invention] that the compounds mentioned are identical to those which have been obtained by hydrolysis of the corresponding 4'-alkyl-4-biphenylcarbonitriles. In addition, the analysis 45 values of the elements of compounds 6-9 in Table 4 are shown in Table 5 below.

Table 5

Analysis values of the elements of compounds 6-9 from Table 4

Number of Molecular Calculated Value Analysis Value Fertilize compound formula

Table 4

c

H

C.

H

©

C19H22O2

80.8

7.9

80.6

8.1

©

C19H2202

80.8

7.9

80.8

8.1

©

C19H2202

80.8

7.9

80.6

8.0

©

C18H20O2

80.6

7.5

80.4

7.6

7

622 245

A certain equivalent amount of the above-mentioned biphenylcarboxylic acid is added with one or more molar equivalents, preferably 1.2-2.5 molar equivalents, of thionyl chloride; the resulting mixture is heated under reflux for a predetermined time and forms acid chloride; the excess amount of thionyl chloride is then distilled off and the acidic chloride is dissolved and diluted by adding a suitable inert solvent such as benzene, toluene, etc.

On the other hand, the p-cyanophenol (preferably as a purified substance) is dissolved in equal parts by mol as the acid chloride or in a slightly supersaturated molar ratio in several parts of a water-soluble basic solvent (such as pyridine) which is capable of Dissolve cyanophenol completely at room temperature; this resulting solution is then cooled. The above solution of clean chloride in an inert solvent is added dropwise to the cooled solution with stirring. After completion of this drop infusion, the compound is gently warmed in a water bath or similar device for one hour. (When using an inert solvent such as benzene, the reaction mixture is kept at a constant temperature due to the reflux, so that the use of such a solvent is preferable. After the reaction is completed, the reaction mixture is cooled with ice and poured onto ice. The mixture thus obtained is added an appropriate amount of an inert solvent is added; the resulting mixture is placed on a separatory funnel, followed by a separating water layer, a wash with dilute hydrochloric acid, a saturated aqueous sodium chloride solution with a 2% sodium hydroxide portion, on which the inert solvent is distilled off, so that a slightly yellowish-looking solid is obtained, which is purified for recrystallization with a suitable solvent (e.g. ethanol), so that a colorless crystal of p-cyanophenyl ester [with reference to formula ( I) of 4-alkyl-4 '-Biphenylcarboxylic acid (Formula II above)]. This crystal forms a nematic liquid crystal at a melting point of about 100 ° C or higher temperatures (depending on the number of carbons in the 4-alkyl group), the nematic liquid crystal temperature fluctuation range being 100 ° C or above. If the temperature rises above this range, an isotropic liquid is created. The ester of formula (I), on the other hand, in which R = 8, forms a smectic liquid crystal at a melting point of 101 ° C. and forms an isotropic liquid at 202 ° C.

As mentioned above, the compounds of the above formula (I) have a wide temperature range and can be used for liquid crystal display panels of the type with an electric field effect according to the following illustrative method:

1 g of p-cyanophenyl-4-n-hexyl-biphenyl-4'-carboxylate (R = n-C6Hi3) in the formula (I) mentioned is in 29 g of a 3: 2 (by molecular weight) mixture of p-methoxybene cylidene-p'-n-butylaniline and p-ethoxybenzylidene-p'-n-butylaniline dissolved. The resulting mixed liquid crystal has a crystallization temperature of 0 ° C or less and forms an isotropic liquid at 61 ° C. This liquid mixed crystal is sealed in a twisted configuration type liquid crystal cell consisting of two plates of transparent indium oxide electrodes covered with a cotton cloth in rubbed in a certain direction and placed between two polarizing plates. The behavior of the liquid mixed crystal was investigated using such a well-known and prepared as above liquid crystal light tube apparatus of the electric field effect type. As a result, it was confirmed that said (I) of (R = n-C6H13) had a positive dielectric anisotropy. This liquid mixed crystal has a field strength threshold voltage of 4 volts and a saturation voltage of approximately 6 volts each at room temperature.

A 3: 2 (by molecular weight) mixture of p-methoxybenzylidene-p'-n-butylaniline without part of the above (I) of (R = n-C6H13) is a nematic mixture which is an isotropic liquid at 56 ° C forms, but has a negative dielectric anisotropy and therefore has no field strength sensitivity as mentioned above.

The nematic temperature range of a liquid crystal substance composed essentially only of liquid crystal substances with positive dielectric anisotropy is expanded for another example of use of the (I) compound mentioned. This gives, for example, a eutectic mixture consisting of 4-n-pentyl-4'-cyanobiphenyl, 4-n-heptyl-4'-cyanobiphenyl, 4-n-pentyloxy-4'-cyanobiphenyl, 4- n-heptyloxy-4'-cyanobiphenyl and 4-octyloxy-4'-cyanobiphenyl from the mixing of these compounds in a ratio of 45, 24, 10.9 and 12% (expressed in molar ratios) in the order given above, the nematic Temperature range from -8 ° C to + 50 ° C is sufficient. At this temperature range, the upper limit temperature is insufficient, and this liquid crystal substance immediately forms an isotropic liquid in the natural environment in which the liquid crystal display mechanism is placed, for example in the case of direct sunlight, the display mechanism not being actuated. In order to increase the upper limit of the nematic temperature range, one can consider the ratio of a component with a higher limit temperature such as. B. 4-n-octyloxy-4'-cyanobiphenyl (upper nematic temperature limit: 80 ° C) higher than the previously specified ratios. In this case, however, the mixed liquid crystal would not form a eutectic mixture, and the lower limit of the nematic temperature range is increased, whereby crystal precipitation in the vicinity of 0 ° C could take place. In contrast, a liquid crystal of a eutectic mixture with a larger nematic temperature margin can be prepared by adding 5 kinds of compounds, any one or more of the compounds (I) of the present invention. For example, the composition of a eutectic mixture from the simultaneous use of 2 compounds of formula (I) of the present invention, where R = n-C5H11 and R = n-C7Hi5, is approximately as follows: 4-n-pentyl-4 ' Cyanobiphenyl (42%), 4-n-heptyl-4'-cyanobiphenyl (22%), 4-n-pentyloxy-4'-cyanobiphenyl (9%), 4-n-heptyloxy-4'-cyanobiphenyl (8% ), 4-n-octyloxy-4'-cyanobiphenyl (11%),

(I) (R = n-CSHU) (3%), and (I) (R = n-C7Ha5) (5%).

The nematic temperature range of this mixed liquid crystal is between -11 and + 64 ° C; Even at temperatures lower than the lower temperature limit, the liquid crystal has a strong tendency to cool down quickly and crystal precipitation does not occur by itself. If, on the other hand, the compounds of (I) are added in larger proportions than in the ratios mentioned above, the upper temperature limit increases; then the compounds of (I) precipitate at lower temperatures, so that it can be concluded that the above-mentioned proportions are practically optimal to look at. The reason that the nematic temperature range is expanded by adding small amounts of the compounds of (I)

should lie in the fact that (I) with R = n-CsHn itself

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

622 245

8th

has a nematic temperature range from 110 to 1313 C and that (I), with R = n-C7H15, also has a temperature range of 104-210 ° C.

The methods for producing the compounds of (I) of the present invention are exemplified as follows. In the following examples 1-5, e.g. for 4-n-alkylbiphenvlcarboxylic acid, those with an n-alkyl of 4-8 carbon atoms are shown; however, absolutely comparable results can be obtained in cases where those with a branched alkyl group of 5-7 carbon atoms and a methyl group are used as a distributed chain.

example 1

Preparation of p-cyanophenyl-4-pentylbiphenyl-4'-carboxylate (I, R = n-CSH11)

50 g of 4-n-pentyl-4'-cyanobiphenyl and 500 g of 70 percent by weight sulfuric acid were placed in a glass flask with 3 necks of 2 liters capacity and heated with a jacket heater with stirring at reflux for 2.5 hours. The resulting reaction mixture was cooled with water; then 500 ml of water was added, followed by separation of a solid by a glass filter, washing with water and recrystallization with glacial acetic acid to prepare 45.7 g of a 4-n-pentyl-biphenyl-4'-carboxylic acid [(II), R = C5Hh], which is a colorless crystal with a molecular formula of C18H20O, (composition: C 80.6%, H 7.5%, O 11.9% as calculated values and C 80.3%, H 7.6 %, O 12.1% as observed values) and a melting point of 177 ° C; the substance formed a smectic liquid crystal at temperatures above the melting point.

25 ml (too much) of thionyl chloride were added to 45 g of this biphenylcarboxylic acid; the resulting mixture was heated under reflux for one hour to form acidic chloride. After the excess thionyl chloride was distilled off, 100 ml of benzene was added. Into a solution obtained by dissolving 20.5 g of p-cyanophenol in 80 ml of pyridine and then cooling, the above acid chloride in a benzene solution was added dropwise with stirring, followed by refluxing in a water bath for one hour, ice cooling, pouring out Ice, further adding 300 ml of benzene, transferring to a separatory funnel, suctioning off the water layer, washing with dilute hydrochloric acid, washing with a saturated aqueous solution of common salt with a 2% content of sodium hydroxide, further washing with a saturated aqueous solution of common salt and distillation of benzene, so that a light yellow solid formed, which was recrystallized from methanol and 32 g of a colorless crystal [(I), R = C5Hn] with a molecular formula of C2SH23O2N (composition: C 81.3%, H 6.3 %, O 8.7%, N 3.8% as calculated values, and C 81.4%, H 6.3%, O 8.8%, N 3.6% as observed values) and a melting point of 110 ° C , and formed a nematic liquid crystal at temperatures above the melting point and an isotropic liquid at 231 ° C [infrared spectrum of (I), R = CsHi, is shown in Fig. 1.]

Example 2

Preparation of p-cyanophenyl-4-n-hexylbiphenyl-4'-carboxylate in [(I), R = n-C6Hi3]

5 g of 4-n-hexyl-4'-cyanobiphenyl, 40 ml of diethylene glycol, 4 ml of water and 2 g of sodium hydroxide are placed in a 3-neck glass flask of 200 ml capacity and heated with stirring for 25 hours, followed by one Acidification by hydrochloric acid, a by filtration and recrystallization with glacial acetic acid to achieve 4.1 g of 4-n-he-xyl-biphenyl-4'-carboxylic acid (II), which is a colorless crystal with the molecular formula Q9H22O2 (composition: C 80 , 8%, H 7.9%, O 11.3% as calculated values and C 80.4%, H 8.1%, O 11.5% as observed values) with a melting point of 170-171 ° C and formed a smectic liquid crystal at temperatures above the melting point.

5 ml (too much) of thionyl chloride were added to the 3.5 g of this phenylcarboxylic acid; the resulting mixture was heated under reflux for one hour to form an acid chloride, followed by distilling off the excess of thionyl chloride with the addition of 30 ml of benzene, further adding a solution of 1.5 g of p-cyanophenol dissolved in 5 ml pyridine, refluxing for one hour, water cooling, adding cold water, transferring to a separatory funnel, washing with acid and alkali as in Example 1 and distilling off the benzene to give a slightly yellowish solid which resulted from Ethanol was recrystallized to add 1.5 g of a colorless crystal [(I), R = C6HI3], with a molecular formula of C26H25O2N (composition: C 81.4%, H 6.6%, O 8.3%, N 3.7% as calculated values and C 81.2%, H 6.8%, O 8.5%, N 3.6% as observed values) and a melting point of 102 ° C; the crystal formed a nematic liquid crystal at temperatures above the melting point and an isotropic liquid at 214 ° C. [Infrared spectrum of (1), R = C6Hi3, cf. Fig. 2.]

Example 3

Preparation of p-cyanophenyl-4-n-heptyl-biphenyl-4'-carboxylate [(I), R ^ n-CyH «]

50 g of 4-n-heptyl-4'-cyanobiphenyl and 500 g of 70% by weight sulfuric acid are placed in a 3-neck, 2-liter glass flask and heated on a jacket heater with stirring at reflux for 2.5 hours, followed by water cooling Adding 500 ml of water, separating the resulting solid by filtering with a glass filter, washing with water and recrystallization with glacial acetic acid to give 47.3 g of 4-n-heptyl-biphenyl-4'-carboxylic acid [(II), R = C7Hi5], which is a colorless crystal with the molecular formula C20H24O2 (composition: C 81.0%, H 8.2%, O 10.8% as calculated values and C 81.2%, H 8.3 %, O 10.5% as observed values) with a melting point of 163 ° C., which formed a smectic liquid crystal at temperatures above the melting point.

47 g of this biphenylcarboxylic acid were added to 25 ml (too much) of thionyl chloride; the resulting mixture was heated under reflux for one hour to form acid chloride; then the excess amount of thionyl chloride was distilled off and 400 ml of benzene was added. To a solution of 20 g of p-cyanophenol in 80 ml of pyridine and cooled, the above-mentioned benzene solution of acid chloride was added dropwise with stirring, then heated in a water bath under reflux for one hour, cooled by water, poured onto ice, placed in a separating funnel, the water layer is suctioned off, washed with dilute hydrochloric acid, then with. saturated aqueous solution of table salt containing 2% sodium hydroxide and the benzene distilled off, resulting in a slightly yellowish solid which was recrystallized from ethanol and 49.5 g of a colorless crystal [(I), R = C7HiS] with a Molecular formula of C27H2702N (composition: C 81.6%, H 6.8%, O 8.1%,

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

9

622 245

N 3.5% as calculated values, and C 81.9%, H 6.8%, O 7.9%, N 3.6% as observed values) with a melting point of 104 ° C., which gave a nematic liquid crystal at temperatures above the melting point and formed an isotropic liquid crystal at 210 ° C. [Infrared spectrum of (I), s R = C7H15, cf. Fig. 3.1

Example 4

Preparation of p-cyanophenyl-4-n-butyl-biphenyl-4'-carboxylate [(I), R = n-C4H9] io

4-n-Butyl-4'-cyanobiphenyl was used as the raw material, the treatment being carried out in the same manner as shown in Example 1 to obtain 4-n-butyl-biphenyl-4'-carboxylic acid [(II), R = C4H9], a colorless crystal with a molecular formula of C17H1802 (composition: C 80.3%, 15 H 7.1%, O 12.6% as calculated values and C 81.0%, H 6.0%, O - as observed values) and a melting point of 199 ° C, and formed a smectic liquid crystal at temperatures above the melting point.

This biphenylcarboxylic acid was brought together in reaction with p-cy-20 anophenol in the same manner as shown in Example 1; the resulting reaction product was purified and gave a colorless crystal [(I), R = C4H9] with a molecular formula of C24H21O2N (composition: C 81.1%, H 6.0%, N 3.9%, O 9, 8% as calculated values and C 81.0%, H 6.0%, N 3.8%, O - as observed values) and a melting point of 125.2 ° C, thereby a nematic liquid crystal at temperatures formed above the melting point and an isotropic liquid at 234 ° C. [Infrared spectrum of (I) with R = C4H9, cf. 30 Fig. 4.1

C.

Infrared spectra of compounds 10-13 from Table 6 55 are shown in Figs. 6-9.

Carboxylic acid (Formula II) is obtained using steps 1-4 of Equation (1) above. Example 10 shows this.

Example 10 60

Preparation of 4'-n-pentyl-4-biphenylcarboxylic acid (Compound 2 of Table 4).

First level 65

560 g of anhydrous aluminum chloride granules and 1 l of Ni-trobenzene are placed in a 5 l glass flask with 3 necks and stirred with water cooling until dissolved.

Example 5

Preparation of p-cyanophenyl-4-n-octyl-4'-carboxylate (I, R = n-C8Hi7)

The 4-n-octyl-4'-cyanobiphenyl was used as a raw material and the treatment was carried out in the same manner as our Example 1 to obtain a 4-n-octyl-biphenyl-4'-carboxylic acid (II, R = C8H17 ) to be produced as a colorless crystal with a molecular formula of C21H2602 (composition: C 81.3%, H 8.4%, O 10.3% as calculated values and C 81.1%, H 8.5%, O - as observed values) with a melting point of 1510 C, which gave a smectic liquid crystal at temperatures above the melting point.

This biphenylcarboxylic acid was reacted with p-cyanophenol in the same manner as our Example 1; the resulting reaction product was purified to give a colorless crystal (I, R = C8H17). with a molecular formula of C28H29O2N (composition: C 81.7%, H 7.1%, N 3.4%, O 7.8% as calculated values and C 81.5%, H 7.1%, N 3, 4% O - as observed values) with a melting point of 101 ° C, which formed a smectic liquid crystal at temperatures above the melting point and an isotropic liquid at 202 ° C. [Infrared spectrum of (I), R = C8H17, cf. Fig. 5.]

Examples 6-9

Using 4'-alkyl-4-biphenylcarboxylic acids 6-9, as described in Table 4 above, production processes were carried out as described in Example 1, from which the corresponding p-cyanophenyl esters (compounds 10 -13 in Table 6).

Yield Analytical (%)

values

C H

81.3 6.4 74

81.3 6.6 80

81.2 6.6 78.5

81.2 6.1 82

A solution of 600 g of diphenyl and 482.5 g of acidic valerian chloride, dissolved in one liter of nitrobenzene (previously provided), was added dropwise to the glass flask over two hours. After the drop infusion was complete, the gas mixture was stirred for one hour. Then it was stirred at 40-45 ° C for two more hours, cooled to room temperature, continuously poured into a mixed solution of 1.3 l of concentrated hydrochloric acid and 1.5 l of water to split the catalyst, and then cooled to 20 ° C . The precipitated crystal was separated by filtration. Nitrobenzene was distilled off from the nitrobenzene layer under low pressure to obtain another crystal. Both crystals were recrystallized from ethanol to give 881 g of crystals of 4-n-pentanoylbi

Table 6

p-Cyanophenyl ester from substances 6-9 in Table 4

r * CK2 ~ Ö ~ Ö "C0 ° ~ O ~ CN (III)

No.

R in side chain

Nematic temperature range

Elemental analysis

Calculated

value

C H

Ç °) © © ©

C-C-C-C-

I.

c

C-C-C-C-

I.

C.

C-C-C-C-

I.

c

C-C-C-

125.5-187.5 105.5-193.9 102.3-204.4 145.1-208.4

81.4 6.6

81.4 6.6

81.4 6.6

81.4 6.3

622 245

10th

phenyl (melting point 79-79.5 ° C) (yield 95% based on biphenyl).

Second step

1000 g of 4-n-pentanoylbiphenyl, 2 l of diethylene glycol and 564 g of potassium hydroxide were introduced into a 5 l glass flask with 3 necks and heated with stirring to a uniform solution temperature at about 80 ° C., which was then cooled to 50 ° C. with the addition of 738 ml of hydrazine hydrate, heating with stirring, distilling off low-boiling residue (mainly water) until the temperature of the reaction mixture was stabilized at 185 ° C; under reflux, this mixture was heated to 185-190 ° C for 4 hours, cooled to room temperature, with the addition of 1.51 water and 400 ml of hexane, stirring, washing the hexane layer with an aqueous solution of sodium chloride and final distillation, whereupon 659 g of 4-n-pentylbiphenyl (boiling point 166-167 ° C / 6 mm Hg) (yield 70%) gave.

Third step

392 g of anhydrous aluminum chloride granules and 700 ml of nitrobenzene were filled in a 5 1 glass flask with 3 necks and dissolved with stirring. A solution of 600 g of 4-n-pentylbiphenyl and 220 g of acetyl chloride dissolved in 500 ml of nitrobenzene (previously provided) was added dropwise to this glass flask over an hour, followed by stirring for one hour, further stirring at 40-45 ° C during 2 hours, cooling to room temperature, careful pouring into a mixed liquid consisting of 250 ml of concentrated hydrochloric acid and 1.25 l of water, distillation of nitrobenzene from the nitrobenzene layer under reduced pressure, separation of the resulting solid by filtration and recrystallization Ethanol, which gave 597 g of 4'-n-pentyl-4-acetyl-biphenyl (boiling point 81-82 ° C) (yield 84%).

Fourth stage

883 g of 4'-n-pentyl-4-acetylbiphenyl were added to a 30 liter nitro steel reactor [equipped with stirrer, reflux condenser and a funnel for drop infusion (added)], a further 3,751 p-dioxane and dissolved with stirring. On the other hand, 1.8 kg of bromine was added dropwise and dissolved in a solution of 2 kg of sodium hydroxide, dissolved in 7.5 l of water, then cooled to 10-15 ° C. The resulting bromine acid solution was at about 10 ° C kept. The solution was dropwise added to the above p-dioxane solution over 50 minutes, followed by stirring at 35-40 ° C for 3 hours, left to stand overnight, then 250 g of sodium bisulfide was added with stirring and concentrated with 2.81 Neutralized hydrochloric acid; the resulting solid was separated by filtration, washed with water, dried and recrystallized from 6 liters of acetic acid to give 747 g of 4'-n-pentyl-4-biphenylcarboxylic acid with a melting point of 177 ° C (smectic liquid crystals in formation) ( Coverage 84%).

This product was subjected to a mixed test with 4'-n-pentyl-4-biphenylcarboxylic acid, which resulted from example series 1, and showed no decrease in the melting point. The two infrared absorption spectra were also the same. It was concluded that there were two identical substances.

Example 11

Preparation of compounds 3-9 in Table 4.

In exactly the same manner as in Example 10, reactions of the first to fourth stages were the same as the above

Formula (1) was carried out using diphenyl and the corresponding acid chloride as starting materials to obtain substances 3-9 from Table 4 above as end products.

Next, the following examples and references to the liquid crystal materials of the present invention will be described.

As stated above, the liquid crystalline materials of the present invention are those which are one kind or more of p-cyanophenyl esters of 4-alkyl-4'-biphenylcarboxylic acids (in which the alkyl is a linear alkyl group chain with 4-8 carbon atoms or a branched alkyl group chain with 5-7 carbon atoms and with the methyl group as a branched group) (these esters are mentioned in the further course of this work as p-cyanophenyl ester).

Among them, the following liquid crystal compounds show improved properties:

A. Liquid crystal substances consist of (^ p-cyanophenyl ester of this invention and (T) 4-alkyl-4'-cyanobiphenyl and / or 4-alkoxy-4'-cyanobiphenyl;

B. liquid crystal substances consisting of (^ p-cyanophenyl ester of the present invention, (2) 4-alkyl-4'-cyanobiphenyl, (3) 4-alkoxy-4'-cyanobiphenyl and (?) 4-cy-ano- 4 "-n-pentylterphenyl and / or 4-cyano-4" -n-hexylterphenyl, and

C. Liquid crystal substances consisting of ^^ p-cyanophenyl ester of this invention, mandatory p'-cyano-phenyl-p-alkyl benzoate, (^ mandatory p-alkyl-p'-cy-anobiphenyl and (4) mandatory pn-butylbenzoic acid-p ' -n-alkyl ester or p-anisic acid-p'-n-pentylphenyl ester.

The following Examples 1-7, given as reference, are used for comparison purposes with the above-mentioned liquid crystal materials A and B.

The following examples 12-13; 31-38; and 39 ^ 1 are given to show the structures and efficacies of liquid crystal substances respectively A, B and C.

The liquid crystal substance A corresponds to the embodiment mentioned in item (6) above in this invention, the liquid crystal substance B for naming (7) this invention and the liquid crystal substance C for naming (8) this invention.

With respect to the liquid crystal substance C of the present invention or its mention (8) in the present document, the uses of the compounds within the groups (A), (B), (C) and (D) are discussed in detail below.

With regard to the compounds (IV) of groups (A), two or three types are selected, at least two types each having an alkyl group as R in the formula (IV). If two or more compounds each having an alkoxy group as R in the formula (IV) are selected, the lower limits of the nematic temperature latitude of liquid crystal substances C are not reduced sufficiently and the working properties at lower temperatures are lower. Furthermore, even if four types or more of the group (A) compounds are used, the properties of the liquid crystal substances C are not improved. The number of Group A compounds available for use represents 35-50%, preferably 40-47% by mole, based on the total number of mixed substances.

The number of substances from Group B that are available for use are 20-30% depending on the mole, based on the total number of mixed substances.

Within the compounds of formula (V), that of (n = 5) has a nematic temperature range of 22.5-35 ° C, and that of (n = 7) has a nematic temperature range of 28-4-2 ° C. Accordingly, when used in numbers greater than 30%, the

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

11

622 245

upper limits of the nematic temperature fluctuations of liquid crystal substances C to an undesirable level for the purpose of the present invention, e.g. B. below 50 ° C, reduced. (V) (n = 7) is preferably used as a 2: 1 mixture (by mol) with (V) (n = 5). The presence of 5 compounds from group (B) takes a special part in the increase in the reactivity of electro-optical effects of liquid crystal substances C.

Compounds of group (C) are prescribed singly or individually among new compounds of item (1) of this invention, and one type can usually be used up to 8-13% by weight based on the compounds C. If two types or more are used in appropriate amounts, evidence can be given for increasing the upper limits of the nematic temperature range for liquid crystal substances C, but not for increasing the lower limits of this range. On the other hand, if they

After moles are used, they tend to slow down the reaction rate of substance C, which is undesirable for the purpose of display.

Finally, with regard to the use of the compounds from group (D), it was possible to effectively demonstrate the possibility of reducing the lower limits of the nematic temperature range of liquid crystal substances C 25 and thus expanding the temperature range. Preferred temperature ranges are between 15 and 30%

by moles. The liquid crystal substances (liquid crystal substances C) of item (8) of this invention as set forth in Examples 39-41 listed below can maintain a nematic state above about -10 to + 60 ° C; even if they are kept at -20 ° C for several weeks, crystal precipitation does not occur. In addition, the reaction rates are sufficiently high.

35

Reference examples 1-7

Liquid crystal compounds, consisting of the types and ratios of compounds listed in Table 7,

were examined. As a result, the lowest limit of the nematic temperature range was -18 ° C (reference example 6) and the highest limit of this range was 61 ° C (reference example 7). Among them, since Reference Examples 3 and 7 had an upper temperature limit of 60 ° C or above, are compared with a group mentioned in Table 10 below, which group is in accordance with the above-mentioned liquid crystal substances A of the present invention.

Then the lower temperature limits of the reference example were 5 ° C or 1 ° C, i.e. H. both higher than - 5 to - 100 C of the liquid crystal substances of the group in Table 10. It is clear from this that their applications as liquid crystal elements are limited. In addition, Reference Examples 5 and 6 with a low temperature limit of less than -10 ° C are compared with a group mentioned in Table 8 below; this group corresponds to the liquid crystal substances of the present invention. Furthermore, the upper limit temperatures of the reference examples are 42 ° C or 44 ° C, i.e. both much lower than temperatures above 60 ° C of that group in Table 8 which is consistent with the liquid crystal substances of the present invention. It is therefore obvious that their practical usability is unsatisfactory.

In addition, other reference examples 1, 2 and 4 are compared with a group mentioned in Table 9 below, which corresponds to the liquid crystal substances of the present invention. Here the lower limit temperatures are within a range of 0 to -10 ° C, although such temperatures are insufficient, whereas the upper temperature limits are within a range of 45 to 54 ° C, ie they are not only significantly lower than the temperatures above that 80 "limit encountered in the liquid crystal substances of the group shown in Table 9, but do not even reach 60 ° C, which is the lowest within the upper temperature limits of the liquid crystal substances of the present invention.

Table 7

Liquid crystal substances of reference examples 1-7 (percent by weight)

Name of the connection No. of the reference example

1

2nd

3rd

4th

5

6

7

4-n-pentyl-4'-cyanobiphenyI

47.0

52.0

-

41.7

32.1

30.0

-

4 '-4-n-hexylcy anobiphenyl

-

-

-

29.6

26.9

-

4-n-heptyl-4'-cyanobiphenyl

29.6

-

42.4

25. i

16.7

15.1

35.8

4-n-propyloxy-4'-cy anobiphenyl

-

-

-

-

8.6

16.2

4-n -pentyloxy-4 '-cy anobiphenyl

12.2

14.9

18.3

10.2

6.5

5.7

15.1

4-n-heptyIoxy-4'-cyanobiphenyl

11.2

13.7

16.9

9.4

5.9

5.3

13.9

4-n-octyloxy-4'-cy anobiphenyl

-

18.8

22.4

13.6

9.2

8.4

19.0

Total

100.0

100.0

100.0

100.0

100.0

100.0

100.0

Nematic temperature range

lower limit ° C

-4

-2

5

-9

-17

-18

1

upper limit ° C

45

54

60

49

42

44

61

(Travel) ° C

49

56

65

58

59

62

62

Examples 12-17 liquid crystal substances consist of the compounds listed in Table 8, the types and ratios 65 of which were prepared to observe their nematic liquid crystal temperature margins, to experience those values as shown in the lower part of the table (lower limit and upper

Limit, 0 C) is listed. The lower limits were 10 ° C or lower, while the upper limits were 60 ° C or higher; under normal use, these substances were water or moisture resistant, air resistant (oxidation resistant), heat or light resistant.

622 245 12

Table 8

Liquid crystal substances of Examples 12-17 (percent by weight)

Name of the connection No. of the example

12 13 14 15 16 17

4-n-pentyl-4'-cy anobiphenyl

27.6

38.9

35.6

47.3

32.1

38.6

4-n-hexyl-4'-cy anobiphenyl

24.5

-

-

-

30.4

-

4-n-heptyl-4'-cy anobiphenyl

13.7

19.1

20.3

21.6

17.3

22.6

4-n-pentyloxy-4'-cyanobiphenyl

5.2

7.6

8.1

8.7

-

9.1

4-n-hexyloxy-4 'cyanobiphenyl

4.8

7.0

7.4

8.0

-

8.3

4-n-heptyloxy-4'-cyanobiphenyl

7.6

10.5

11.1

11.8

-

12.3

4-n-pentyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

2.4

3.4

3.5

3.8

3.0

-

4-n-hexyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

4.1

5.4

5.7

-

5.0

-

4-n-heptyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

6.2

7.9

8.3

8.8

7.4

9.1

4-n-octyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

3.9

5.2

-

-

4.8

-

Total

100.0

100.0

100.0

100.0

100.0

100.0

Nematic temperature range

lower limit ° C

-20

-12

-11

-10

-15

-10

upper limit ° C

61

75

70

64

60

60

(Travel) ° C

81

87

81

74

75

70

Examples 18-21 Liquid crystal substances consisting of types and ratios of compounds as listed in Table 9 were prepared and their nematic liquid crystal temperature margins were observed to give values as now shown in the lower part of the table (lower limit and upper limit ° C). The upper limits were

10 ° C or below, while the upper limit was 80 ° C or 30 higher. These substances were stable to moisture, air (oxidation), heat or light in cases of ordinary use. In Table 9, the temperature range of Example 18 also relates to the range of fluctuation in Table 10 below, so that the composition of Example 35 18 is of particularly high quality.

Table 9

Liquid crystal substances of Examples 18-21 (percent by weight)

Name of the connection

No. of example 18 19

20th

21st

4-n-pentyl-4'-cy anobiphenyl

4-n-hexyl-4'-cyanobiphenyl

41.4

-

-

-

4-n-heptyl-4'-cyanobiphenyl

-

34.5

30.9

-

4-n -pentyloxy-4 '-cyanobiphenyl

9.9

14.8

13.0

18.4

4-n-hexyloxy-4'-cyanobiphenyl

9.1

13.7

12.0

17.0

4-n-heptyloxy-4 '-cyanobiphenyl

13.0

18.5

16.5

22.1

4-n-pentyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

4.2

5.9

-

7.1

4-n-hexyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

6.6

-

8.2

10.7

4-n-heptyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

9.4

12.6

11.3

14.0

4-n-octyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

6.4

-

8.1

10.7

Total

100.0

100.0

100.0

100.0

Nematic temperature fluctuation range

lower limit ° C

-6

2nd

0

9

upper limit ° C

81

83

92

122

(Travel) ° C

87

81

92

113

Examples 22-30 liquid crystal substances consisting of types and ratios of the compounds shown in Table 10 were prepared and their nematic liquid crystal temperature fluctuations were observed to calculate those values as shown in the lower part of the table (lower limit and upper limit ° C) are listed. The lower limits were from -5 to -10 ° C, while the upper limits were above 65-60 ° C; these substances were water insensitive (moisture resistant), air insensitive (resistant to oxidation) and light or heat insensitive in cases of ordinary use.

13

622 245

Table 10

Liquid crystal substances of Examples 22-30 (percent by weight)

Name of the connection

No. of the example

22

23

24th

25th

26

4-n-pentyl-4'-cyanobiphenyl

_

38.6

40.7

45.3

40.0

4-n-hexyl-4'-cyanobiphenyl

44.1

-

-

-

-

4-n-heptyl-4'-cy anobiphenyl

-

23.1

24.9

-

23.8

4-n-pentyloxy-4'-cy anobiphenyl

10.6

-

-

12.0

9.6

4-n-hexyloxy-4 'cyanobiphenyl

9.8

-

-

11.1

-

4-n-heptyloxy-4'-cyanobiphenyl

13.9

12.5

13.5

15.6

13.0

4-n-pentyI-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

4.5

4.0

4.3

5.0

4.1

4-n-hexyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester 4-n-heptyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester 4-n-octyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

7.1 10.0

6.4 9; 2 6.2

6.9 9.7

11.0

9.5

Total

100.0

100.0

100.0

100.0

100.0

Nematic temperature fluctuation range

below limit ° C

-5

-8th

-7

-5

-8th

upper limit ° C

75

75

71

71

63

(Travel) ° C

80

83

78

75

71

Table 10 (continued)

Name of the connection

No. of the example

27th

28

29

30th

4-n-penty 1-4 'cyanobiphenyl

40.0

43.3

41.4

43.0

4-n-hexyl-4'-cyanobiphenyl

-

-

-

4-n-heptyl-4'-cyanobiphenyl

24.1

27.0

25.0

27.3

4-n-pentyloxy-4 '-cyanobiphenyl

-

-

10.1

-

4-n-hexyloxy-4'-cyanobiphenyl

9.0

9.3

-

4-n-heptyloxy-4'-cyanobiphenyl

13.1

14. n

-

-

4-n-pentyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

4.2

4.7

4.3

4.7

4-n-hexyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

-

-

-

7.4

4-n-heptyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

9.6

10.4

9.9

10.4

4-n-octyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

-

-

7.2

Total

100.0

100.0

100.0

100.0

Nematic temperature fluctuation range

lower limit ° C

-8th

-5

-7

-5

upper limit ° C

64

62

62

76

(Travel) ° C

72

67

69

81

Next, Reference Examples 3 and 7 are compared with a group mentioned in Table 12 below, which themselves correspond to the above-mentioned liquid crystal substances B. Here the lower limit temperatures are 5 or 10 C, i.e. H. higher than -6 to -9 ° C from the liquid crystal substances of the group in Table 12. From this, it is clear that the uses for liquid crystal display elements with these substances are limited. Further, Reference Examples 5 and 6 having a low temperature limit of -10 ° C or below were compared with a group mentioned in Table 11 below; this group corresponds to the liquid crystal substances of the present invention. The upper limit temperatures were 42 or 44 ° C, i.e. much lower than those temperatures above 70 ° C of the group in Table 11 which are consistent with the liquid crystal substances of the present invention. It is therefore obvious 55 that their practical applicability is limited.

Further, Reference Examples 1, 2 and 4 were compared with a group in Table 12 according to the liquid crystal substances of the present invention. Here the lower limit temperatures are within a range of 0 to 60 -10 ° C, although such temperatures are rather insufficient, whereas the upper limit temperatures are within a range of 45 to 54 ° C, i.e. not only are they much lower than the temperatures above 80 ° C of the liquid crystal substances of the group in Table 12, but they also reach 70 ° C, which is the lowest within the upper temperature limits of the above-mentioned liquid crystal substances B.

622 245

14

Examples 31-35 liquid crystal substances consisting of types and ratios of compounds shown in Table 11 were prepared and their nematic liquid crystal temperature fluctuation range was observed to calculate the values in the lower part of the table (lower limit and upper limit,

° C). The lower limits of the liquid crystal temperature fluctuation range are -10 ° C or below, while the upper limits reached 70 ° C or higher, whereby these substances are stable against water (moisture), air 5 (against oxidation) and heat or light in the case kept from ordinary use.

Table 11

Liquid crystal substances of Examples 31-35 (percent by weight)

Name of the connection

No. of example 31 32

33

34

35

4-n-pentyl-4'-cyanobiphenyl

25.1

30.5

32.1

32.2

36.2

4-n-hexyl-4 '-cyanobiphenyl

21.7

-

-

-

-

4-n-heptyl-4'-cyanobiphenyl

12.0

16.2

17.5

17.6

20.7

4-n-pentyloxy-4'-cyanobiphenyl

4.5

6.3

6.8

6.9

8.3

4-n-hexyloxy-4 'cyanobiphenyl

4.2

5.8

6.3

6.4

7.6

4-n-heptyloxy-4 '-cyanobiphenyl

6.8

9.0

9.6

9.7

11.3

4-n-pentyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

2.2

2.9

3.1

3.1

-

4-n-hexy 1-4 'biphenylcarboxylic

acid-p-cyanophenyl ester

3.7

4.7

5.1

5.1

-

4-n-heptyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

5.6

7.0

7.4

7.5

8.5

4-n-octyl-4'-biphenylcarboxylic

acid-p-cyanophenyl ester

3.4

4.5

4.8

4.9

-

4-cy ano-4 "pentylterphenyl

5.1

6.2

-

6.6

7.4

4-cyano-4 "-n-hexylterphenyl

5.7

6.9

7.3

-

Total

100.0

100.0

100.0

100.0

100.0

Nematic temperature fluctuation range

lower limit ° C

-22

-16

-14

-14

-11

upper limit ° C

77

92

84

84

71

(Travel) ° C

99

108

98

98

82

Examples 36-38 liquid crystal substances consisting of the types and ratios of compounds shown in Table 12 were prepared and their nematic liquid crystal temperature fluctuation range was examined to show the values in the lower part of the table (lower limit and upper limit, ° C). The lower limits of the liquid crystal temperature fluctuation range were -6 ° C or below, while the 40 upper limits were at 80 ° C or above, and these substances were stable to water (moisture-proof),

Air (resistant to oxidation) and to heat or light in the event of ordinary use.

Table 12

Liquid crystal substances of Examples 36-38 (percent by weight)

Name of the connection No. of the example

36

37

38

4-n-pentyl-4'-cyanobiphenyl

-

38.1

42.1

4-n-hexyl-4'-cy anobiphenyl

38.2

-

-

4-n-heptyl-4'-cyanobiphenyl

-

22.6

-

4-n-pentyloxy-4'-cyanobiphenyI

9.0

-

10.7

4-n-hexyloxy-4'-cy anobiphenyl

8.3

-

9.8

4-n-heptyloxy-4'-cyanobiphenyl

12.0

12.3

14.0

4-n-pentyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

3.9

3.9

4.5

4-n-hexyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

6.2

6.3

-

4-n-heptyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

8.8

9.0

10.1

4-n-octyl-4'-biphenylcarboxylic acid-p-cyanophenyl ester

6.0

-

-

4-cyano-4 "-n-pentylterphenyl

7.6

7.6

8.5

4-cyano-4 "-n-hexylterphenyl

-

-

-

Total

100.0

100.0

100.0

Nematic temperature fluctuation range

below limit ° C

-8th

-9

-6

upper limit ° C

91

82

83

(Travel) ° C

99

91

89

15

622 245

In Table 11, the liquid crystal temperature fluctuation range of Example 32 also covers the temperature fluctuation ranges of the Examples from Table 12, and the substance composition of Example 32 is particularly favorable.

5

Example 39

16.8 g of 4'-cyanophenyl 4-n-butylbenzoate (IV, R = n-C4H9),

19.3 g of 4'-cyanophenyl 4-n-heptylbenzoate

(IV, R = n-C7H15), OK

13.5 g of 4'-cyanophenyl 4-n-heptyloxybenzoate (IV, R = C7H1sO)

10.7 g of 4'-phenyl 4-n-heptylbiphenylcarboxylate (IV, n = 7)

28.9 g of 4-n-pentyl-4'-cyanobiphenyl (V, n = 5) and 15 34 g of 4'-n-butylbenzoic acid 4'-n-heptyloxyphenyl ester

(VII, R = C7H1sO)

were mixed under heating and gas evacuation in a Schlenk tube to give them a liquid crystal structure. The transition point from nematic to isotropic temperature was 60 ° C; only when the mixture remained at -20 ° C for a long time did a crystal form, which on the other hand melted at -5 ° C and formed a nematic phase.

Was this mixture of substances for a cell for rotating, polarized light with a rotated angle of 90 ° 25 (so-called twisted nematic type cell), the threshold voltage for activation (voltage required for a 10% reaction) was 1.2 V, and the reaction saturation voltage (90% reaction) was 1.8 V; when brought up to 3 V, the response time was 80 milliseconds, while the 30 decay time was 150 milliseconds. During the measurements, the temperature was 25 ° C and the frequency used was 32 hearts.

Example 40

16.8 g of 4'-n-butylbenzoic acid 4'-cyanophenyl ester 35 (IV, R = n-C4H9),

18.5 g of 4'-cyanophenyl 4-n-hexylbenzoate

(IV, R = n-C6H13),

19.3 g of 4'-cyanophenyl 4-n-heptylbenzoate

(IV, R = n-C7H15), 40

28.9 g of 4-n-pentyl-4'-cyanobiphenyl (V, R = n-CSHU),

15.3 g of 4'-n-pentylbiphenylcarboxylic acid 4'-cyanophenyl ester (VI, n = 5) and

27.0 g of 4'-n-butylbenzoic acid 4'-n-heptyloxyphenyl ester

(VII, R = C7H1S),

were mixed in the same manner as in Example 39 to obtain a liquid crystal substance mixture. The nematic-isotropic transition temperature was 64 ° C, and only when the mixture of substances had been kept at -20 ° C for a long time did a crystal form, which however melted at -10 ° C and formed a nematic phase. When this mixture of substances was used for the same rotating polarized light cell as in Example 39, the threshold voltage (required to initiate a 10% response) was 1.2 volts and the reaction saturation voltage (90% response) at 1.8 V. When brought up to 3 V, the response time was 80 milliseconds and the decay time was 150 milliseconds. Both the temperature and the frequency used were the same as for Example No. 39.

Example 41

12.28 g of 4'-cyanophenyl 4-n-butylbenzoate

(IV, R = n-C4H9),

14.13 g of 4'-cyanophenyl 4-n-heptylbenzoate

(IV, R = n-C7H15),

9.47 g of 4'-cyanophenyl 4-n-hexyloxybenzoate

(IV, R = n-C6H130),

18.26 g of 4-n-pentyl-4'-cyanobiphenyl (V, R = n-CSH11), 9.31 g of 4-n-heptylbiphenylcarboxylic acid-

4'-cyanophenyl ester (VI, n = 7) and 16.55 g of 4'-anisic acid 4'-n-pentylphenyl ester

(Replacement connection for VII),

were mixed together in the same manner as in Example 39 to obtain a liquid crystal substance mixture. The nematic-isotropic transition temperature was 67 ° C, and only if the mixture remained at -20 ° C for a long time did a crystal form, which melted again at -10 ° C and formed a nematic phase. When this mixture of substances was used for the same rotating polarized light cell as in Example 39, the threshold voltage (required to initiate a 10% response) was 1.0 V, while the reaction saturation voltage (90% response) was 1.7 V was. When brought up to 3 V, the response time was 80 milliseconds, the decay time was 130 milliseconds. The measurement temperature and frequency were again the same as in Example 39.

s

5 sheets of drawings

Claims (5)

622 245 1. A process for the preparation of p-cyanophenyl-4-alkyl-4'-biphenylcarboxylates, wherein said alkyl group is linearly linked and has 4-8 carbon atoms or a branched-chain alkyl group with 5-7 carbon atoms and a methyl group as branched chain Group, characterized by the condensation of a 4-alkyl-4'-biphenylcarboxylic acid, wherein said alkyl has the same meaning as the definition given above, with p-cyanophenol. 2. A process for the preparation of p-cyanophenyl-4-alkyl-4'-biphenylcarboxylates, in which the said alkyl group is linearly linked and has 4-8 carbon atoms or a branched-chain alkyl group with 5-7 carbon atoms and a methyl group as branched linked group has, characterized by the preparation of a 4-alkyl-4'-biphenylcarboxylic acid, which is obtained by hydrolysis of 4-alkyl-4'-cyanobiphenylene, the latter having said alkyl has the meaning given above, with an acid or a Alkali, and by the condensation of 4-alkyl-4'-biphenylcarboxylic acid, with p-cyanophenol. 2nd PATENT CLAIMS 3. A process for the preparation of p-cyanophenyl-4-alkyl-4'-biphenylcarboxylates, wherein said alkyl group is linearly linked and has 4-8 carbon atoms or a branched chain alkyl group with 5-7 carbon atoms and a methyl group as branched chain Group has, characterized by the preparation of a 4-alkyl-4'-biphenylcarboxylic acid by oxidation of 4-alkyl-4'-aze-tylbiphenylene, the alkyl having the meaning mentioned in the latter substance, and by the condensation of 4. Use of at least one p-cyanophenyl-4-alkyl-4'-biphenylcarboxylate, in which the said alkyl group is linearly linked and has 4-8 carbon atoms or a branched-chain alkyl group with 5-7 carbon atoms and a methyl group as a branched-chain group has in a liquid crystal substance. 5. Use according to claim 4, characterized in that the liquid crystal substance (i) p-cyanophenyl-4-alkyl-4'-biphenylcarboxylate and (ii) 4-alkyl-4'-cyanobiphenyl and / or 4-alkoxy-4'- Contains cyanobiphenyl. 6. Use according to claim 4, characterized in that the liquid crystal substance (i) p-cyanophenyl-4-alkyl-4'-biphenylcarboxylate, (ii) 4-alkyl-4'-cyanophenyl, (iii) 4-alkoxy-4 ' Cyanobiphenyl, and (iv) 4-cyano-4 "-n-pentene-phenyl and / or 4-cyano-4" -n-hexylterphenyl. 7. Use according to claim 4, characterized in that the following four groups are used in the liquid crystal substance: (A) two or three kinds of compounds derived from a group consisting of 4'-alkylbenzoic acid 4'-cyanophenyl esters represented by the general formula K-ö-eoo- O- CN wherein R is a linearly linked alkyl group having 4-8 carbon atoms or a linearly linked alkoxy group 4-alkyl-4'-biphenylcarboxylic acid, with p-cyanophenol. 5-8 carbon atoms, where the two or at least two of the three compounds mentioned have a linearly linked alkyl group as R, vu-o-o- « or a mixture of them with: c7hi5- € H> ci1 ' (C) one, two or more types of compounds selected from the group consisting of 4-alkylbiphenylcarboxylic acid-4 'cyanophenylene expressed by the general formula CnH2n + l ~ O-0-COO-0-CN wherein CnH2n + i is a linearly linked alkyl group having 4-8 carbon atoms or a branched chain alkyl group having 5-7 carbon atoms and having a methyl group as a branched chain group, and (D) one or more compounds from that group consisting of 4'-alkylphenyl 4-n-butylbenzoate, wherein the R is either the n-heptyl, n-hexyloxy or the n-heptyloxy group represented by the formula n-Bu - ^ - COO - ^ - R or 4-anisic acid 4'-n-pentylphenyl ester with the formula cn3o-0-coo-Q-csH11 alone or their mixture with one of a kind or more compounds from the group consisting of: 4-n-butylbenzoic acid 4'-alkylphenyl ester.