DE2519659B2 - p-n-alkyl-p "-cyanoazoxybenzenes, processes for their preparation and compositions containing them - Google Patents

Description

NO

wherein R has the meanings given in claim I, condensed with p-cyunoaniline and the resulting p-n-alkyl-p'-cyanoazobenzene oxidized with peracetic acid.

3. Nematic liquid crystal compositions with a positive dielectric anisotropy, characterized in that they consist of a mixture of two or more of the pn-alk vl-p'-eyanoazoxybenzenes of the formula given in claim I! exist.

4. Nematic liquid crystal compositions having a positive dielectric anisotropy, characterized in that it consists of a mixture of (A) at least one c! er p-n-alkylp'-eyanoazoxybenzenes the formula I and (B) given in claim I at least one of the compounds of the Schiff's ^ base type formula

CH = N

(N)

wherein R _{1 is} an n-alkoxy group with 1 to 8 carbon atoms and R _{2 is} an n-alkyl group with 1 to 8 carbon atoms or R _{1 is} an n-alkyl group with 2 to 8 carbon atoms and R _{2 is} an n-alkoxy group with 1 to 8 carbon atoms, exist, the two components A and B being present in a weight ratio of 0.05 <A / A -f B <I.

5. Nematic liquid crystal compositions having a positive dielectric anisotropy, characterized in that they consist of a mixture of (A) at least one of the p-n-alkylp'-cyanoazoxybenzo! e of the formula I and (C) given in claim 1 at least one of the compounds of the azoxy type of the formula

(III)

in which one of the radicals R or R _{4 is} an n-alkyl group with I to 8 carbon atoms and the other is an n-alkoxy group with I to S carbon atoms or each of the radicals R and R _{4 is} an n-alkyl group with 3 to 8 carbon atoms,

wherein the two components A and C in a weight ratio of 0.05 <A / A + C <I exist.

where R is an η-butyl-, n-penlyl-, n-hexyl-, n-Hcp-IyI- or n-octyl group.

2. Process for the preparation of the p-n-alkylp'-cyanoazoxybenzenes of the formula I given in claim I, characterized in that a p-n-alkylnitrosobenzene is used in a manner known per se the formula

The invention relates to p-n-alkyl-p'-cyanoa / i-.xybenzenes, a process for their production and nematic liquid crystal compositions containing them, with a positive dielectric anisotropy.

Nematic Flüssigkristallvcrbindungen or nematic Flüssigkristallzusammenselzungen (hereinafter referred to as N-liquid crystal compounds or N-Fliissigkrislall compositions hereinafter) are used for electro-optical devices in which the phenomenon is utilized that change their optical properties when an electric field is applied. Electro-optical display devices in which N-liquid crystal materials are used can be divided into two groups, depending on the dielectric anisotropy of the N-liquid crystal material used. One group includes devices in which a dynamic sliver mode (DSM), that is, an optical scattering phenomenon caused by the collision of an ion and an N liquid crystal region when an electric field is applied to an N liquid crystal material having a larger dielectric constant is in a direction perpendicular to the longitudinal axes of the molecules than the dielectric constant in the longitudinal direction is applied, a nematic Flüssigkristaü-Matcrial mi ¹ ie a negative dielectric anisotropy (hereinafter referred to as Nn-Flüssigkrislall-Malcrial) is used. Another group includes devices in which an electric field effect mode (FEM), ie a change in the inclination or torsion of the N-liquid crystal molecules, caused by applying an electric field to an N-liquid crystal material with a larger dielectric constant in a longitudinal direction of the Molecules as being used in a direction perpendicular to the long axes of the molecules, ie a nematic liquid crystal material with a positive dielectric anisotropy (hereinafter referred to as Np liquid crystal material). Many of the last-mentioned FEM type devices are so-called "torsion effect type display devices" (hereinafter referred to as TN display device) in which a change in the torsion (twisting) of the molecules (one of the electric field effect modes) is exploited.

The Np liquid crystal compounds according to the invention or Np liquid crystal compositions are used for the TN type display devices.

The aim of the present invention is to provide new Np liquid crystal compounds for TN-type display devices and a process for their manufacture. The aim of the invention is in particular new Np liquid crystal compositions for use in the display device dated Specify TN type. It is also the aim of the invention.

a new Np liquid crystal composition for indicate the TN-type display device. over a wide temperature range, the room temperature um.il, a nematic liquid-crystal phase having.

The invention relates to new Np-HüssigkrislalI compounds, namely, p-n-alkyl-p'-cyanoazoxybenzenes. which by the following general Formula are identified / calibrated

CN

(I)

wherein R is an n -utyl-. n-Pentyl-, n-Hxyl-. n-heptsl- or n-octyl group.

If you have two or more of these p-n-Alkjlp'-eyanoazoxybenzenes mixed with one another, an NP liquid crystal composition is obtained. their iiemalier Liquid crystal phase temperature range or mesomorphic range is wider than that each component of the composition. In addition, a new Np-FRissigkristall composition is obtained, which has a broad mesomorphic range encompassing room temperature, if one mixes with one another (A) at least one p-n-alkylp'-cyanoazoxybenzene with (B) at least one compound of the following formula of the Schiffsche type !! Base:

> - CH- N- /

(H)

wherein R ₁ denotes an n-alkoxy group with I to 8 carbon atoms and R denotes an n-alkyl group with I to π 8 carbon atoms or R ₁ denotes an n-alkyl group with 2 to 8 carbon atoms and R denotes an n-alkoxy group with I to H carbon atoms ,
in a weight ratio of 0.05 <A / A + B <I, or by mixing component (A) with (C) w at least one compound of the azoxy type of the general formula

(III)

wherein one of the radicals R, or R ₄ . one n-alkyl group with I to 8 carbon atoms and the other an n-alkoxy group with I to 8 carbon atoms or -> o each of the radicals R ₃ and R _{4 denote} an n-alkyl group with 3 to 8 carbon atoms,
in a weight ratio of 0.05 <A/A + C <I. In preferred embodiments of the present invention, the weight ratios of the components are included

0.05 <A / A + B <0.3 or 0.05 <A / A + tt < 0.2 and 0.05 <A / A + C <0.3 or 0.05 <A / A + C <0.2.

The invention is described below with reference to wi explained in more detail on the drawings. It shows

Figure 1 shows the infrared absorption spectrum of p-n-butyl-p'-cyanoazoxy benzene,

F i g. 2 the gas chromatogram of pn-butylp'-cyanoazoxybenzene. b ^r >

3 shows the mass spectrum of p-n-butyl-p-cyanoazoxybenzene,

Fig. 4 is a phase diagram of an Nn liquid crystal composition; consisting of a mixture of p-methoxyben / .y Helen-p'-n-buly! aniline (MBBA) and p-ethoxybenzylidcn-p'-n-butylaniline (EBBA).

Fig. 5 is a phase diagram of an Nn liquid crystal composition. consisting of a mixture of MBBA. EBBA and p-Ethoxybenzylidene p'-ii-heptylaniline (EBHpA),

6 shows a phase diagram of an inventive Np liquid crystal composition consisting of from a mixture of an Nn liquid crystal composition, made by mixing MBBA. EBBA and EBHpA in equal parts by weight, and p-n-butyl-p'-eyanoazoxybenzene.

7 shows a phase diagram of a device according to the invention Np liquid crystal composition consisting of from a mixture of an Nn liquid crystal composition, prepared by mixing MBBA, EBBA and EBHpA in equal parts by weight, and p-n-hexyl-p'-cyanoazoxybenzene,

8 shows a phase diagram of an inventive Np liquid crystal composition consisting of a mixture of an Nn liquid crystal composition (Composition \), made by mixing p-methoxy-p'-n-butylazoxybenzene. p-methoxy-p'-n-hydroxylazoxybenzene. p-Methoxyp'-n-octylazoxybenzene and p-ethoxy-p'-n-butylazoxybenzene in equal parts by weight, and p-n-biityl-p'-cyanoazoxy benzene.

F i g. 9 a phase diagram of an inventive Np liquid crystal composition, consisting of from a mixture of the composition \ and p-n-hexyl-p'-cyanoazoxybenzene.

The Np liquid crystal compounds according to the invention of the general formula I can be prepared by condensing p-n-alkylnitrosobenzenes the general formula

NO

wherein R has the meanings given above, with p-cyanoaniline to form p-n-Aikyi-p'-cyanoazobenzenes the general formula

R-

N = -N-

-CN

wherein R has the meanings given above, and then oxidizing the resulting p-n-alkyl-p'-cyanoazobenzenes with peracetic acid, the can be prepared by mixing a hydrogen peroxide solution with acetic acid.

The reaction described above can be represented by the following reaction equation:

MO + NH, - <O

—► R- <O> -N - = - N— < O

CN

CN + H ₂ O

R - <O VN - N - <O
H ₂ O ₂ + CH ₁ COOH

The p-ii-alkylnilrosobenzene used as starting material can be prepared by nitrating n-alkylbenzenes or p-n-alkylanilines oxidized, the resulting p-n-Alkylnitioben / ole converted into p-hydroxyamino-n-alkylbcn / ols using zinc powder and ammonium chloride and this nitrosated. The crude p-n-alkylnitrosobenzene obtained in this way can be cleaned, for example, by steam distillation. The oxidation reaction with Pcrcssigsäurc is expedient at temperatures of 70 to 80 ° C for 6 to 8 hours stirred. When the reaction temperature is lowered below the above range, the Response time very long. If on the other hand the temperature

is increased to a value above the specified range, by-products are formed. The crude pn-alkyl-p'-cyanoazoxyben / ols are purified by crystallization from ethyl alcohol.
The compounds of formula I were made by her

1 infrared sorption spec ι rum. herüasch ro histogram and their mass spectrum identified. The F i g. I.

2 and 3 each show an infrared absorption spectrum, a gas chromatogram or a mass spectrum of p-n-biityl-p'-cyanoazoxybenzene. By (iaschromatography of ρ- η -butyl-p-cyanoa / oxybenzene it was confirmed that two isomers of the following given formulas are available in approximately the same weight quantities:

-N-- I O N- <O V-CN

CN

In Fig. 2 the weight ratio is both isomers about 1: 1. although it is not clear which maximum corresponds to which isomer. at ρ - η - Pcntyl - ρ - cyanoazoxybcnzol, ρ - η - Hexylp ' - cyanoazoxybenzene, ρ - η - Hcptyl - ρ '- eyanoazoxybenzene and p-n-ociyl-p'-cyanoa / .oxybcnzol the same results as for p-n-butyl-p'-eyanoazoxybenzene obtain.

The Np liquid crystal compounds of the formula I. and the Np liquid crystal compositions obtained by mixing two or more of the compounds of Formula 1 show a broad mcsomorphic range (Mcsomorphic range). In the following tables 1 and II are the transition point (transition point). the transition from the crystalline into the nematic liquid crystalline phase (CN point) and the transition point (transition point) the transition from the normal liquid-crystal to the isotropic phase (Nl point) with respect to these Np liquid crystal compounds and compositions are given.

Table I.

Vcrhiiuliinucn

CN-I'iinkic (Ci

Nl-I'iinklc
I Cl

CIl, - (CH,)., - \ O: · --N = N- / O> CN

HO

CH., - (CI I, I ₄ <O / Nj -Nx O) -CN

IIS

CII ₁ - (CH,), · O · N _ = -_ N ■ ■■. O> - ■ CN O

106

CII, (CH,) ,, ■ O .- N - ^ _ N O> - CN

CII, (CW ₂ ), O ■ Nj-_N · O, - CN C)

100

1 dragonfly II

iK'nii'M uiul (i

CN-l'iinkk-

Nll'imku-

I Cl I Cl

CII, I, I,

NN i> CN: CH, (CII ₂ I _4. O .-- N_ __N "· O CN

1: 1

(11.1 (11.1, O NN (J CN: CII ₁ · ΚΊΙ, Ι, ■. O / -Nj = NO CN cT O

I :!

107

CII, K II,), ON NO CN: CH, ΚΊΙ, Ι ,. ■ O / - N_j-_N · ■ O. CN

1: 1

CU, - (CH, I ₁ O NN O CNiCII ₁ - (UI ₂ I ₇ 'O> - N _ = - N ■' O, CN 1: 1

T "

5X

I DO

CH, ICH, Ij ONN ■■ O CNiCH ₁ - (UI ₂ ), O > - "Nj = N ■ · 'O / CN 1: 1

~ 7>

I 12

CII, -ICH, I ₄ ON _N O CN: CII, ICH,) ,, · O> ■ - N- ^ N- <O / CN 2: 1

70

117

(11.1 (11.1, O NN O, CN: CH, ((11.1, O > - N- = N ■ ■ ■ '' O / CN 2: 1

50

KIS

CH, «11.1. O NN O ■ CN: CII, (CII ₂ K ■ O --N — N -O / CN 1: 2

CII, I,), ONN ■ 'O

CNiCII., I ₂ K O. Ν__Ν · .Ο / CN
O

O /

O/

: I: 1 49 112

(11,! CH ₂ I, ■ O N__N O CN: CH, - (CII ₂ I ₄ 'O. - N_ _N -O

CNiCII., ■ K II,) 'J NN - <O / CN

1: 1: 1

4 (i HIS

(11, ICH ₂ I ₁ O NJ N ·· '(J ■ CNiCII ₁ -IUI,), O. · Nj_N · O

O "

CN CiI ₁ ■ ΚΊΙ, Ι. -Ci- N_J ^ I -λ O ■ CN
O

1: 1: 1

As can be seen from the above table,

a broader meso-peripheral region (mesomor- mi phicbcreK'h) is obtained if one mixes two or more tier ρ- η -alkyl- p'-cyanoj / oxyben / ole niileinaniler. Ungen is not critical, and any of troubling ratio h ^r are applied.

The compounds of line I and the compositions of which can be used as Np-I-Lüssigkristall-Ma-

leriidien used for TN-type display devices will. The mesomorphic areas of these Np-l-'lüssigkrislall-Miiterialien lie on the I hole temperature side above room temperature, as the above Tables 1 and II show. Hs was also found that a wider meso-peripheral area encompassing the room temperature can be achieved, if you at least one of the compounds of the formula I with at least one of the compounds of l'ormel II from Schill's base-1 \ p or the Vcr-

809 511/336

bindimgen of the formula III of the Λ / .oxy type mixes, wherein the compounds of formula I with the Compounds of the formulas 11 and III are readily miscible. The Np liquid crystal compositions thus obtained are also within the scope of the present Fründtmg.

Table III

In the case of the compounds of the formula II from the SchiΙΓ-sclien Base type is known Nn liquid crystal compounds.

Here are the CN points and the NI points of the debt from Schiffsche !! Base types are given in Table III below.

<N-I'mikk-

ι (ι

\ l l'imku I (I

CII ₁ O ■ -. O ■ CU N <O ■ ICH,), -CH ₁

CII ₁ O · O ■ CII N - [O '■ (ClK) ₁ -CII,

C ₂ II, O ■ ·, O · CII - NO. (CH,), - CH ₁ SO

CJI ₅ OO; ■ CH - N ■ O

SI)

CH, O · ■: O. '·· CH N <O ^s - (CH,), - CH,

CH ₁ - (CH ₂ I ₁ O \ O · CH N, O · CJU

65

cn, (CH,), o - <ο;> cn ν - \ ο ■ iciio.rcii,

CH ₁ - (CH ₂ KO \ OV CW N \ O ^x (ClI _- ,),. · CII., 70

CH ₁ (CH ₂ UO _N ο; ■ cw ν _x ο cn.,

Cl I, (Cl I ₂ ) O χ O; CH N \, O ■ CII _- , 70

/.1

CH ₁ (CH ₂ ), see O CW N \ O ^x O-CJI ₅ NO

CH ₁ (CH ₂ I, O CH N - .. '. O ^s OC ₂ II,

75

CH ₁ (CH ₂ K _N O · CW N _x Cl. · O-Cll,

s ¹ ,

CH ₁ (ClI, K. C) ■ CW NO ■ O-CJI,

The dutch mixing of / wet oiler more of the compounds of the Schilischcii rabbit-type produced Nu-These'.igkrisiall / iisiall- / iisiigencl / uiigen generally have a lower CN point as a result of the freezing impression depression and therefore their tnesoinorphic range \ ei broadly in comparison / u leather component Λϊχ compositions.

line the / tisüberset / ungcn from the boat hare T \ ρ wc.sl a Nn-l-'lüssigki ^l isliill- / iisaminensel / iing. which has been herueslelll by mixing MHIIA and Ι-ΊΙΗΛ in an i'cciLincU-n Verhiilliiis herueslelll. a broad mesomoiphic area (mesomoiphatic area) encompassing a range. How out

hi ι the T'i g. 4 licrvorgehl. has a ^! - liquid crystal composition with a (lew ichlsverhüllnis from MHHA to FHBA around 7: .1 to 4: 6 a broad mesomorphic area. and especially in the case of the application of the mixing ratio uin I: 1

ίο becomes the widest mcsiimorphic height (I 5 to 5S C) echo.

(icmäl.t a preferred embodiment of the l-'i'Tmdiiiig becomes eim · Np l-liissigki isiall-Ziisaiiimeu

set / ung. clic a room temperature brcilcn mesomorphic Hcrcich aul'wcisl. to reverberate that one has at least one p-n-alk \ l-p -csanoa / o \ yben / ol with a Nn liquid crystal composition. which is a mixture of MBHA and IiHUA, mixes in which the (weight ratio / uischen 7: 3 iiiul 4: d lies. Most preferred is a composition in tier the mixture of the same (iewichlsleilen MBHA and FiBIiA see.

[it is known that when a suitable Amount of IiHIIpA of a mixture au *, equal Ciewiehlsieilen MIJHA and IiHBA / ugesei / l, the CN-point is lowered and on the other hand the NI-point is increased, and therefore one gets one mesomorphic region (mesomorphic region that is wider than that of the mixture of equals Ciewichlsteilen MBBA and HBBA.

As shown in FIG. 5 it can be seen that the C'N-Iink is the Nn liquid crystal composition. by Forwarding of IiHIIpA to the Nn-hiüssigknMail- / us ... consisting of a mixture of the same (iewichlsleilen MBBA and IiBBA. made has been. lower than ■; that of the latter Nn liquid crystal composition when the ratio HBIIpA / MBBA + HHBA below about 1 (MBHA: HBBA: HHHpA = - I: I: 2). on the other hand the Nl point increases. if the amount of added HBIIpA increases. Regarding ties CN points it should be noted that if the ratio HBIIpA / MBBA l · IiBBA is below about I. liegl (MBBA: HBBA: HBHpA = 1: 1: 2). the mesomorph Area consisting of a mixture of the same (iewichlsleilen MHA and HBBA and "IiBIFpA Nn liquid crystal sums are practically wider than that of a mixture

Table IV

of the same Nn liquid crystal composition (consisting of MHBA and HHHA). The mesomorphic range which is preferred in practice can be obtained in particular if the ratio EBHpA / MBBA 4 EBBA of the Nn liquid crystal composition is approximately within the range of 1/4 (M BBA: KBBA: HHHpA - = 2: 2: 1) to ¹ J / 11 IMBBA: HHHA: HHHpA - 11:11:18). Even more preferred is an Nn-FKissigkrislall composition. in which the ratio EBHpA / MBBA I HBBA lies within the range of about 3/7 IMBBA: IiHBA: LiBHpA 7: 7: 6) to 2/3 (MHHA: IiHBA: HBHpA - 3: 3: 4). Most preferred is an Nn liquid crystal composition. in which the ratio EBHpA / MBBA ι IiBBA is about 1/2 (MBBA: HBHA: HHHpA -1: 1: I), which has the lowest CN point and a broad mesomorphic range comprising room temperature. According to a preferred embodiment of the invention, Np liquid crystal compositions are used. which have a broad mesomorphic range encompassing a room temperature, obtained by mixing a suitable amount of at least one pn-alkyl-p'-cyanoazo.xybenzene with the Nn liquid crystal composition of MBBA. HBBA and HBHpA in the ratio EBHpA / MBBA f HBBA of less than about I (MHHA: HBHA: IiHHpA = 1: 1: 2) mixes.

With the compounds of the azoxy- '! > ρ of the above formula 111 is also known Ni-liquid crystal compositions. The CN points and the Ni points of typical azoxy-type compounds are in Table IV below specified.

V'ci biiuliimicn

'N -l'imkk-I C)

Nl-I'iiiikk-I C I

CII ₁ O. C) ^Ν _ιΝ Ο

K (I

CH ₁ O. O ■ N _ "---- = _ N- - O ■ (CHj) ₄ -CH ₁
O

CH ₁ O <O ■ N-_N-- \ O. ICIL1-CH ₁
O

.S 2

CII ₁ OO N__N O (CII,) ,, -Ul,
O

CII ₁ O - .. C) N JNi- C) ■ (CI I, ι- CII,
O

4i

; II ₅ O -. (.) * NN '> ICII-I, -CII ₁
O

I ')

CIIO

N N

cn,

17th

rortset / iini '.

14th

Vci hiiulaiiui. ·!

( ¹ NI ¹ UiIkU- (I

Nl-I'iiiiku-I Cl

C ₂ IU) O N _ "_ N- C) KTI ₂ I, ClI, O

K) O

(.'Ji ₅ O ■ O ^N _r_J>'

i I ₂ ) ,. (U,

K) C)

K) - ClI ₁

97

CI-I ₁ - (CH ₂ M) O '--- N = _N - _χ Ο> - (CH ₂ ), - CH.,

CH., (CIK) ₁ O - χ O * · N = N- \ O / - (CH ₂ ), ■ C \],

CH., - (CH ₂ I ₅ O ■ - <O> - NN ■ ■■. O V- (CH ₂ ), - CH.,

CH, - (CH ₂ ), ~ <O / Nj = NA, O / - (CH ₂ ), · CH,

CH, ■ (CH,)., - ~ < Ό VN == N "<'O / - (CU,)., · CH,

66

(monoimp)

27

CH, ■ (CH,) ₄ - \ O; ^ N = N- \ O> - (CH,) ₄ ■ CiI,

CH, (CH ₂ ), - <O > ~ N =

- (CH ₂ ) ₅ -CH,

CH, ■ (CH ₂ ) ,, - <O> - N = N- <O> - (CH ₂ ) ,, · CH,

CH., ■ (CH ₂ ) - - ^ O> - N = N- \ O> - (CH,) ₇ ■ CH,

Compositions made by mixing min- therefore they comprise a room temperature

Deslcns one of the compounds of the formula I with a broad mcsomorphic range (Mesomorphic

Compound of the Λ / .oxy type of the formula IiI or range). For example, one indicated by Mi

Mixtures thereof are also included in the aforementioned three compounds of FIG under the invention-compliant Np liquid crystal ingredients, o azoxy type produced in equal weights!

together / imgen. Composition a mesomorplicn area

Among the liquid crystal compositions, -6 to 79 ° C were found. Also one by mixing voi

The Nn liquid crystal additives are of the A / oxy type

together / .ungcn. by mixing p-Mellioxy- p '- η - hexylazoxyben / ol, ρ - Melhoxy - p' - η - octyl | V - η - bulylazoxybenzene, ρ - melhoxy - p'- n - liexyl- h · -. a / oxybenzene and p-ethoxy-p'-n-butylazoxybcn / ol ii

azoxybenzene and p-methoxy-p'-n-octylazoxybenzene prepared compositions in suitable amounts

have been produced, due to the freezing point points due to the freezing point depression cinei

depression a lower CN-I'iinkl on and lower CN-I'imkl as well as a Raumteniperatu

comprehensive broad niusomorplia area. So has, for example, one by mixing the above-mentioned four compounds of the azoxy type prepared in equal proportions a mcsomorphcn range from - K to Hl C. The two compositions described above are particularly preferred.

The liquid crystal compositions according to the invention, by mixing an appropriate amount of at least one p-n-alkyl-p'-cyanoazoxybenzene with that of the above three azoxy type compounds or the above four azoxy-type compounds consisting of Nn liquid crystal composition was prepared have a broad mcsomorphic range encompassing room temperature therefore useful Np liquid crystal materials for Represent TN-type display devices.

According to the invention, the compounds of the formula I or mixtures thereof are used to form mixtures with the Nn liquid crystal materials a positive one to impart dielectric anisotropy and can accordingly be regarded as a positive dielectric anisotropy mediating agent. The Np liquid crystal composition those of a mixture of one or more p-n-alkyl-p'-cyanoazoxybenzenes and Schiff base type or azoxy type Nn liquid crystal materials may consist of one or more p-n-alkyl-p'-cyanoazoxybenzene be added in an amount of not less than 5% by weight. When the crowd is less than 5% by weight, positive dielectric anisotropy cannot be made in the N liquid crystal compositions be achieved.

In general, the temperature range of the p-n-alkyl-p'-cyanoazoxybenzenes is higher than that of the Schiff base type and azoxy type compounds. Accordingly, the mesomorphic regions become of the Np liquid crystal compositions to higher Temperatures shifted when the amount of p-n-alkyl-p'-cyanoaz.oxybenzene increases. in the In view of this appearance, the amount of the p-n-alkyl-p'-cyanoazoxybcnzoHc) in the Np liquid crystal is - Compositions preferably not more than 30, in particular not more than 20% by weight.

The invention is illustrated in more detail by the following examples.

example 1

0.2 mol of p-cyanoaniline was dissolved in 240 ml of glacial acetic acid of 40 "C and in 0.22 mol of p-n-butylnitrosobenzene, which had previously been purified by steam distillation, dissolved. After cooling to room temperature and after standing in the dark for 4 days, there was a condensation reaction between the p-cyanoaniline and p-n-butylnitrosobenzene. After the reaction was complete, the addition from distilled water crude p-n-butyl-p'-cyanazobenzene precipitated and filtered off. After washing with distilled water and after removal p-n-butyl-p'-cyanoazobenzene was obtained from acetic acid by recrystallization from ethanol. F. 100 "C, which showed a mesomorphic phase when the temperature was reduced.

Then 0.1 mol of p-n-butyl-p'-cyanoazoben-7.0I dissolved in 500 ml of glacial acetic acid, and there were 31 ml

and then 7 hours was long au by heating 74 to 76 "C stirred. The mixture was then added with stirring and under cooling distilled water to the pn-butyl-p'-cyanoazoxybenzol was crystal! ^r> Siert and filtered off. After washing with Learn to distill water and after removing the acetic acid it was purified by recrystallization from ethanol. The mesomorphic range of the product obtained was 56 to 110 "C. This connection was identified by infrared absorption spectrum, gas chromatography and mass spectrum, as indicated in FIGS. 1, 2 and 3.

Example 2

γ, 0.2 mol of p-cyanoaniline were in 240 ml of Eisessif at 40 "C and in 0.22 mol of p-n-pntylnitrosobenzene which has previously been purified by steam distillation had been resolved. After cooling to room temperature and standing for 4 days in the dark a condensation reaction occurred between the p-cyanoaniline and the p-n-pentylnitrosobenzene. To Completion of the reaction was crude p-n-pentylp'-cyanoazobenzene by adding distilled " Water precipitated and filtered off. After the washer

r> with distilled water and after removal the acetic acid was purified p-n-pentyl-p'-cyanoazobenzo by recrystallization from ethanol obtained, m.p. 94 ° C, that when lowering the temperature exhibited a mesomorphic phase.

Thereafter, 0.1 mole of p-n-pentyl-p'-cyanoazobenzene was added dissolved in 500 ml of glacial acetic acid, and 31 ml of a 30% hydrogen peroxide solution were added, and then stirred for 7 hours with a heater at 74 to 76 ° C. After adding distillate

π lated water with stirring and cooling was the p-n-Pentyl-p'-cyanoazoxybenzene crystallized and filtered off. After washing with distilled water and removing acetic acid, it became purified by recrystallization from ethanol. The mesomorphic region of the product obtained was 66 to 118 "C. This compound was determined by infrared absorption spectrum, gas chromatography and mass spectrum identified.

Be i sp i c 1 3

0.2 mole of p-cyanoaniline was dissolved in 240 ml of glacial acetic acid of 40 ° C and in 0.22 mol of p-n-hexylnitrosobenzene which had previously been cleaned by steam distillation, dissolved. After cooling to room temperature and standing in the dark for 4 days, a condensation reaction occurred between the p-cyanoaniline and the p-n-hexylnitrosobenzene. To Completion of the reaction was crude p-n-hexylp'-cyanoazobenzene by adding distilled " τ-) water precipitated and filtered off. After the washer with distilled water and after removal of the acetic acid it was obtained by recrystallization Ethanol obtained in purified p-n-Hxyl-p'-cyanoazobenzo, m.p. 91 "C, which with lowering of the tempera door exhibited a mesomorphic phase.

Then 0.1 mol of p-n-hexyl-p'-cyanoazobenzene was dissolved in 500 ml of glacial acetic acid, and 31 m a 30% hydrogen peroxide solution was added and then heated to 74 bis for 7 days ιό 76 C stirred. After the addition of distilled Water with stirring and cooling, the p-n-Hcxyl-p'-cyanoazoxybcnzol was crystallized and from

♦ illlj - »** · _nivl \ n

and after the acetic acid was removed it became purified by recrystallization from ethanol. The mcsomorphc range of the product so obtained was 68-106 "C. This compound was determined by infrared absorption spectrum, gas chromatography and mass spectrum identified.

Example 4

0.2 mole of p-cyanoaniline was dissolved in 240 ml of glacial acetic acid of 40 "C and in 0.22 mol of p-n-heptylnitrosobenzene, which was previously purified by steam distillation had been resolved. After cooling to room temperature and standing for 4 days in the dark a condensation reaction occurred between the p-cyanoaniline and the p-n-heptylnitrosobenzene. to distilled water was added to the reaction mixture, and then it was extracted with ether, then the solvent was removed and it was subjected to column chromatography (silica gel with a particle size of 0.074 mm benzene). Finally after the recrystallization it was made Ethanol the purified p-n-heptyl-p'-cyanoazobenzene obtained, m.p. 90 "C, which showed a mcsomorphic phase when the temperature was reduced.

Thereafter, 0.1 mole of p-n-Hcptyl-p'-cyanobenzene dissolved in 500 ml of glacial acetic acid, and 31 ml of a 30% strength hydrogen peroxide solution were added, and then stirred for 7 days with heating at 74 to 76 ° C. After the addition of distilled Water with stirring and cooling became the p-n-Hcptyl-p'-cyanoazoxybcnzoi crystallized and filtered off. After washing with distilled water and after removing the acetic acid it was through Umkrislallisalion purified from ethanol. The mesomorphic range of the product thus obtained was at 98 to I 19 C. This compound was determined by infrared absorption spectrum, Gas chromatographic and mass spectrum identified.

Example 5

0.2 mol of p-cyanoaniline was dissolved in 240 ml of glacial acetic acid at 40 C and in 0.22 mol of p-n-octylnitrosobenzene, which had previously been purified by steam distillation, dissolved. After cooling to room temperature and left standing in the dark for 4 days, a condensation reaction occurred between the p-cyanoaniline and the p-n-octylnitrosobenzene. To the Distilled water was added to the reaction mixture and it was extracted with ether, and after that Removal of the solvent, it was subjected to column chromatography (silica gel with a Particle size of 0.074 mm benzene). Finally, after recrystallization from ethanol, it was obtained the purified p-n-Oetyi-p'-cyanoazobenzene, F. 88 C. which showed a mesomorphic phase when the temperature was lowered.

Then 0.1 mole of p-n-octyl-p'-cyanoazobenzene was added dissolved in 500 ml of glacial acetic acid, and 31 ml of a 3 ()% strength hydrogen peroxide solution were then added was stirred for 7 hours with heating to 74-76 ° C. After adding distilled water with stirring and cooling, the p-n-Oetylp'-cyanoazoxybenzene crystallized and sub-filtered. To after washing with distilled water, and after removing the acetic acid, it was recrystallized cleaned from ethanol. The mesomorphic range of the product obtained in this way was 65 to 100 C. This connection would be through the Infrared Ahsor'i ion spectrum, gas chromatography and the mass spectrum identified.

Example 6

An Np liquid crystal composition (preparation) with a mcsoniorphen range at 57 to 115 C was prepared by heating the same Weight parts p-n-bulyl-p -eyanoazoxybenzene and p-n-pentyl-p'-eyanoazoxybenzene to 130 C. around them to convert to an isotropic phase, and mix the same with stirring. In a corresponding way became various Np liquid crystal compositions made by mixing two or more of the following compounds: p-n-Bulylp'-eyanoazoxy benzene, p-n-penyl-p'-cyanoazox \ benzene, p-n-hexyl-p'-cyanoazoxy benzene. p-n-Heplyl p'-cyanoazoxy benzene and p-n-oclyl-p'-cyanoazowbenzene. The mesomorphic regions of these compositions (preparations) are in the table above 11 compiled.

Example 7

Np liquid crystal compositions with a mesomorphic ranges from 20 to 45 C and 29 to 56 C respectively were produced by mixing 20 or 3 ()% by weight of p-n-butyl-p'-cyanoazoxybenzene with 80 or 70% by weight of MBBA (mcsomorphic range 21 to 45 C).

Example 8

An Np liquid crystal composition having a mesomorphic region at 7 to 59 ° C was found prepared by mixing 2 (1 wt% p-n-bulylp-cyanoazoxybenzene with 8% by weight of an Nn liquid crystal composition (mesomorphic range 5 to 59 C). which is a mixture of equal parts by weight of MBBA and p-n-butylbenzylidene-p'-ethoxyaniline (mesomorphic range 61 to 65 C) acted.

Example 9

An Np liquid crystal composition having a mesomorphic region at 28 to 70 ° C was found prepared by mixing 20 wt .- 'Vo p-n-butylp'-eyanoazoxybenzene with 80% by weight of an Nn liquid crystal composition (mesomorphic range 27 to 70 C). which is a mixture of 80 wt .- "/ p-n-Bulylbcnzyliden-p'-alhoxyaniline and 20% by weight / "p-n-butylbenzylidene-p'-methoxyaniline (which, when the temperature is lowered, becomes mesomorphic Phase at 48 to 80 C) acted.

Example 10

Np liquid crystal compositions with a mesomorphic range from - 13 to 60 C or -2 to 65 C were prepared by mixing 80 and 70% by weight, respectively, of an Nn liquid crystal composition (mesomorphic range - 15 to 58 C). which is a mixture of equal parts MBBA and EBBA traded, with 20 and 30 Ge \\ .-% an Np-1'Üissigkrisial! -composition (mesumorphic Range 46 to 105 C). which is a Mixture of equal parts by weight of p-n-butylp'-cvanoazoxyben / .ol. p-n-Pen ty l-p'-cyanoazoxy benzo! tine! ρ η OcIv! ρ 'cvaüüazoxvhcn / u! handek'e.

Ii c i s ρ i e 1 Il

An Np liquid crystal composition with a mesomorphic range from 3 to 67 C was produced by mixing 7 (.> % By weight of the Nn- ί liquid crystal composition of Example IO with 30 (iew .- "/ ii of an Np liquid crystal composition (mesomorphic region 62 to I 13 Cl, which from Same C each parts by weight of p-n-butyl-p'-cyanoa / oxy benzene and j.n-Heplyl-p'-cvanoazoxybeiizole. in

Example 12

Np liquid crystal compositions were prepared by mixing an Nn liquid crystal composition (mesomorphic range -32 to r, 68 C) with p-n-butyl-p'-cyanoazoxybenzene in the in the weight ratios given in Table V below. The mesomorphic areas of the doing The compositions obtained are also in de ι Table V below. ju

Table V

(icivichlsvcrhällnissc / wischen dor Nn-I liissiukri'-lall-Zusjninu'nscl / uiijj and the Np-Hüssigkrisiall-Verhindunt:

95: 5
90:10
HO: 20
70:30
60:40
30:70
H): 90

Mesomoiphe 6 p Areas 68 (Cl 69 -28 69 -26 70 -21 4th 20th

45 S 5 50 108

/ wipe the Nn-Hiissii! i / unL; and dci NpI lu ^ siti

nsi.ill-Vcrhindimu

Mesomoiphe (Ci

- 28 68

- 25 68

(iüH iclilsVL-rhiilliiissu / nischcn der Nii-KHissiL -
krislall- / iisantnicnscl / unu and the Np-l-'lüssijikri .tall-V'erhindiinj;

70:30
60:40
30:70
10:90

The in the F i g. 6 given phase diagram was based on the data in Table V above prepared. From Fig. 6 it can be seen that then, when p-n-butyl-p'-cyanoazoxybenzene is added in amounts of not more than about 20% by weight, useful Np liquid crystal compositions with a very broad mesomorphic range (mesomorphic range) including room temperature will.

Example 13

Np liquid crystal compositions were prepared by mixing the Nn liquid crystal composition of Example 12 with p-n-hexyl-p'-cyanoazoxybenzene (mesomorphic range 68 to 106 C) in the weight ratios given in Table VI below. The mesomorphic regions of the compositions obtained in this way are likewise indicated in the following table VI.

Table Vl

Mesonu! rpliu Uereiehe I ti 6th 70 23 71 50 83 61 100

The in the F i g. 6 is based on the data in Table VI above. As shown in FIG. 7 emerges, is obtained when p-n-hexyl-p'-cyanoazoxybenzene in amounts of no more than about 20% by weight is added, useful Np liquid crystal compositions with a very broad mcsomorphic area that Includes room temperature.

Example 14

Np liquid crystal compositions having a mesomorphic range of 34 to 68 "C and 46 to 76 ^r C were prepared by mixing 20 and 30 wt% of ρ - η - butyl - ρ '- cyanoazoxybenzene with 80 and 70, respectively % By weight ρ, ρ'-di-n-pentylazoxybenzo! (Mesomorphic range 20 to 72 "C).

Example 15

Np liquid crystal compositions having a mesomorphic range from II to 80 ⁰ C or 14-83 C were prepared by mixing 20 and 30, respectively Gcw .-% pn-butyl-p'-cyanoazoxybenzol with 80 and 70 wt % p-methoxy-p'-n-butylazoxybenzene (mesomorphic range 28 to 80 ⁰ C).

Example 16

3 Nn liquid crystal compositions were prepared by mixing 70 or 50 or 30% by weight of p, p'-di-n-pentylazoxybenzene with 30 or 70% by weight of p-ethoxy-p'-n- hexylazoxybenzene (mesomorphic range 38 to 100 ° C). The mesomorphic regions of the thus obtained three compositions were at 8-73 "C and 20 to 77 ° C and 29 to 80 'C. ¹ Np - liquid - crystal compositions having a mesomorphic range 10-74" C and 23 to 79 ° C. and 30 to 8 ° C. were obtained by mixing 80% by weight of each of the above-mentioned Nn liquid crystal compositions with 20% by weight of pn-butyl-p'-cyanoazoxybenzene.

Example 17

Np liquid crystal compositions with a mesomorphic range at -5 to 80 ° C or 5 to 82 ° C were prepared by mixing 80 and 70 wt .- "o an Nn liquid crystal composition (mesomorphic range -6 to 79 'C), which was a mixture of equal weights ρ - methoxy - p' - η - butylazoxybenzene, ρ - methoxyp'-n-hexylazoxybenzene and p-methoxy-p-methoxyp '- η - octylazoxybenzene, with 20 or 30% by weight of an Np liquid crystal composition (mesomorphic range 46 to 105 ¹ C), which is a mixture of equal parts by weight of pn-butyl-p'-cyanoazoxybenz.ol, pn-pentyl-p ' -cyanoazoxybenzene and pn-octyl-p'-eyanoazoxybenzene

Example 18

F.ine Np - liquid - composition having a mesomorphcn range 6-84 ¹ C was prepared by mixing 70 wt .-% of the Nn liquid crystal Zusammcnsetzung of Example 17 with 30 wt .-% of an Np liquid crystal composition ( mesomorphic range 62 to 113 "C), which consisted of equal parts by weight of pn-butyl-p'-cyanoazoxybenzene and pn-heptyl-p'-eyanoazoxy benzo ¹ .

Example 19

Np liquid crystal compositions were prepared by mixing an Nn liquid crystal composition (mesomorphic range -8 to 8IC, hereinafter referred to as composition \), from equal parts by weight of p-methoxyp'-n-butylazoxybenzene, p-methoxy-p'-n-hexylazoxybenzene, ρ - methoxy - p '- η - octylazoxybenzene and ρ - ethoxy - p '- η - butylazoxybcnzol, with p-n-butyl-p'-cyanoazoxybcnzol in the following Table VIl given weight ratios. The mcsomorphic areas of the Compositions are also given in Table ViI below.

Table VII

(iew ichls

scl / ung

relationship / between the / usaninienunil der Np-I Hissigkrisljll-Verbiiuliiny

Mesomorph
Hiche

95: 5 -K 81

90:10 -7 81

80:20 -5 81

70:30 4 85

60:40 17 88

30:70 43 98

10: 90 51106

The phase diagram of FIG. 8 is based on the data in Table VII above I'ig. 8 emerges, you get when that p-n-Butyl-p'-eyaiioazoxybcnzol in amounts of not more than about 20% by weight is added, useful Np - liquid crystal compositions which have a broad mcsomorphic range, room temperature includes.

Example 20

Np liquid crystal compositions were prepared by mixing the composition \ of Example 19 with p-n-hexyl-p'-cyanoazoxybenzene (mesomorphic range 68 to 106 ° C.) in the weight ratios given in Table VIII below. The mcsomorphic areas of the compositions obtained in this way are likewise in the folucndcn Table VIII.

rabclle Vl

C rew ichisvcihalinissc / wipe the /.iisjmmcnsei/unii \ and the Np-FKissiiAiisiall-Vcibindcini;

90:10
80:20
70:30
60:40
30:70
10:90

The phase diagram of FIG. 7 is based on the data in Table VIII above. From FIG. 9 it appears that when the p-n-hexyl-p'-eyano-mzoxybenzene is added in amounts not greater than about 20% by weight, useful NP liquid crystal compositions with a broad mesomorphic area, the room temperature includes.

Mesumorphic
Areas 81 Cl 81 -8th 82 -7 83 -4 86 6th 93 24 100 50 61

For this purpose 9 sheets of drawings

Claims (1)

Patent claims: I. p-n-Alkyl-p'-eyanoazoxybenzenes with a positive dielectric anisotropy by the general formula N = N O> - CN (D