JPS59144770A - Liquid crystal pyrazine derivative - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R is 3-9C aliphatic alkyl; X is CN or 1-5C aliphatic alkoxy). EXAMPLE:2-(4-n-Hexylphenyl)-5-cyanopyrazine. USE:Most of the compounds exhibit the property of liquid crystal in pure form. Useful as a colorless liquid crystal substance stable to heat, light, air and moisture. PREPARATION:The compound of formula I can be prepared by (1) acetylating the compound of formula II by conventional Friedel-Crafts reaction to obtain the compound of formula III, (2) oxidizing the compound with selenium dioxide, (3) reacting the resultant compound of formula IV with the compound of formula Vto obtain the compound of formula VI, (4) reacting the compound with 0.5- 50 times mole of a halogenating agent at 50-200 deg.C, and (5) reacting the obtained compound of formula VII (Y is halogen) with 1-10 times mole of a cyanizing agent or a metal alkoxide in a proper solvent at 20-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel pyrazine derivatives and methods for their production. As liquid crystal pyrazine derivatives, H, 5ch
ubert et al.
(4) 37.

is an alkyl group), J, A, Na5h et al. (Mol,
0ryst.

Liq, 0ryst, 25, 299 (197
4) Reported by ). However, to date, there has been no report on a liquid crystalline compound in which a cyan group is directly attached to the bira(1) gin ring.

The pyrazine derivative provided by the present invention has the following general formula.

(In the formula, R represents an aliphatic alkyl group having 3 to 9 carbon atoms,
(X represents a cyan group or an aliphatic alkoxy group having 1 to 5 carbon atoms) In recent years, liquid crystal displays have been widely used in digital watches, calculators, toys, and the like. In this case, the liquid crystal is generally a mixture of nine different liquid crystal compounds and non-liquid crystal compounds. The pyrazine derivatives provided by the present invention are:

Many of them exhibit liquid crystal properties even when used alone, and are colorless and warm.

Its purpose is that it is stable against light, air and moisture.
Depending on the application, it can be mixed with other liquid crystal compounds or non-liquid crystal compounds (2) and used together with the liquid crystal composition.

In the general formula (1), R has 3 to 3 carbon atoms, such as n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and various isomers thereof. 0 aliphatic alkyl group, X is
cyan group or metquin.

Ethoxy, n-propoxy, n-butoxy, and n-
represents an aliphatic alkoxy group having 5 to 5 carbon atoms, such as pentyloxy and various isomers thereof.

Nine examples of pyrazine derivatives of the general formula (D) include the following compounds.

2-(4-n-propylphenyl)-5-cyanopyrazine, 2-(4-n-butylphenyl)-5-cyanopyrazine, 2-(4-n-pentylphenyl)-5-cyanopyrazine, 2 - (4-n-hexylphenyl)-5-
Cyanopyrazine, 2-(4-n-heptylphenyl)-
5-cyanopyrazine, 2-(4,-n-octylphenyl)-5-cyanopyrazine, 2-((3) 4-n-nonylphenyl)-5-cyanopyrazine.

2-(4-n-pentylphenyl)-5-methquinpyrazine, 2-(4-n-hexylphenyl)-5-methoxypyrazine, 2-(4-n-heptylphenyl)
-5-methoxypyrazine, 2-(4-n-pentylphenyl)-5-ethyl-oxypyrazino, 2-(4-・n-
hexylphenyl)-5-ethoxypyrazine, 2-(
4,-n-heptylphenyl)-15-oxypyrazine, 2-(4-n-pentylphenyl)-,5-n-
Propoquinpyrazine.

2-(4-n-hexylphenyl)-5-n-propoxypyrazine, 2-(4-n-heptylphenyl)-5-
n-propoxypyrazine, 2-(4-n-pentylphenyl)-5-n-butoxypyrazine, 2-(4-n
-hexylphenyl)-15-n-butoxypyrazine,
2-(4-n-heptylphenyl)-5-n-butoxypyrazine, 2-(4-n-butylphenyl)-5-n
-pentyloxypyrazine, 2-(4-n-pentylphenyl)-5-n-pentyloxypyrazine, 2-(
(4) 4,-n-hebutylphenyl)-5-n-pentyloxypyrazine.

The compound of formula (1) can be produced by the following method using 1-alkylbenzene as a starting material.

(5) (In the formula, R is an aliphatic alkyl group having 3 to 9 carbon atoms.

Y represents a halogen atom, and X represents a cyan group or the number of carbon atoms]
-5 aliphatic alkoxy group) 1st step: Alkylbenzene is acetylated with aluminum chloride and acetic anhydride according to the conventional Friedel-Krach reaction method.

2nd step; oxidize 4-alkylacetophenone with selenium dioxide to obtain 4-alkylphenyl glymeexal hydrate. [References; H, 5cbubert.

et al J, prak↑1. Chem, ,
(4) 33, 265 (1966) o'l Third step: 5-(4-alkylphenyl)-2-biracinol is obtained by reacting 4-alkylphenylglyoxal hydrate with glycinamide. [References;
T(,I], Jones, J., Am.

Chem, Soc, , 'i'l, 78 (
1949), S., Sugiura et al.

Pharmaceutical Journal 89.1646 (1969): ].

Fourth step; 5-(4-argylphenyl)-2-
Add biracinol to 0.5 to 50 times the molar amount of a no-rogensing agent (
For example, phosphorus trichloride, phosphorus oxychloride, phosphorus pentachloride, phosphorus tribromide, phosphorus oxybromide, phosphorus pentabromide, triphenate (6
) Nylphosphine dichloride, Triphenylphosphine dibromide, Triphenylphosphine dichloride,
2-(4-alkylphenyl)-5-halogenopyrazine is obtained by heating the mixture with red phosphorus (halogen, etc.) at 50 to 200°C.

Step 5-1; 2-(4-alkylphenyl)=5-
2-(4-
(alkylphenyl)-5-cyanopyrazine is obtained. As the cyanating agent, for example, potassium cyanide-tetrakistriphenylphosphine palladium (KCN-pd
(pph3)4L cupric cyanide, etc., and DMF, DMSO as a solvent.

Examples include NMp, THF, etc. [References;
Naru, Akj, ta et al., 5ynt, hesjs, 97
4 (98]-).

G, Gamus et al., J. A.m., Ohem,
Soc, 78, 2141 (1956)) Step 5-2; 2-(4-alkylphenyl)-5
- Halogenopyrazine is reacted with 1 to 10 times the mole of metal (7) alkoxide in an appropriate solvent at 20 to 200°C to obtain 2-(4-alkylphenyl)-5=alkoxypyrazine. Examples of metal alkoxides include:
DMF is used as a solvent for sodium alkoxide and potassium alkoxide.

Examples include DMSO, THF, and preferably alcohols corresponding to metal alkoxides.

The present invention will be explained in more detail with reference to Examples below.

[Example 1: 12-(4-n-hexylphenyl)-5
-Production of cyanopyrazine First step: To a suspension of 208y of anhydrous aluminum chloride in dichloromethane (], 100 mA), 68mg of acetic anhydride was added dropwise under water cooling. Next, hexylbenzene 97
．． 4y was added dropwise, and the mixture was stirred at room temperature for 2.5 hours. The reaction mixture was poured into ice (1100 g), and the organic layer was separated and washed with water (
After 500 m/+2) l, it was dried over anhydrous sodium sulfate and concentrated. The concentrate was evaporated under reduced pressure to obtain 90.4 g of 4-hexylacetophenone (b, p130-133°C
(1,5mynHfl), IR (liquid film) (8): 2940. 2910. 2845. 1675°1
600, 1465. 1405. 135.5°12
60, ]-]-75crn-1] was obtained.

2nd step; Selenium dioxide, 55.5y dioxane 3
00m/! The mixture was added to a solution of 15 g of water and heated to 80°C to dissolve. 90.42 g of 4-hexylacetophenone was added and heated under reflux for 4 hours. After cooling.

Separate the black insoluble matter (selenium). After concentrating the f solution,
1,300 g of water was added and heated under reflux for 2 hours. After cooling,
The precipitate was collected, washed with n-hexane (300), and dried under reduced pressure. Recrystallize with acetone-water (l:1) 900- to give 4-hexylphenylglyoxal hydrate 66
．． 3y (mp, 78-80℃, IR (KBr):
3400, 3340.2950゜2920.2850,
1685, 16.00, 1215°1105 cm-'
) was obtained.

Step 3: Add glycinamide hydrochloride 11. to a suspension of 23.6 g of 4-hexylphenylglyoxal hydrate in methanol (200 me) at -40°C.・05? was added as a powder. At −30° C., an aqueous solution of sodium hydroxide ((9) NcLOH 9.48 g, water 25 rn1.) was added dropwise. Gradually warm to -20 to -10℃ for 1 hour at -10℃
After stirring for 2 hours at ~0°C and 2 hours at 0°~20°C, 1
Add concentrated hydrochloric acid (1'i'rnl) dropwise below 0°C to adjust the pH.
= 1. Add sodium bicarbonate to pH = 5
The mixture was left at room temperature overnight. Take 1 insoluble material and wash with water (5
0m/X2) and dried to give 21.1p (mp,
141-143℃, IR (KBr): 2950
.

2915.2850,1700,1680,1645°1605.1510.1460.1380.1225z
-1HMR (DMSO-d6): 0.85 (3H
,t), 1.1'7-1.57 (8H,m),
2.58 (2H, t), 7.22 (2H.

tN, '7.78 (2H, d), 8.03 (I
H, d), 8.12 (LH, d), 12.43
(0,'7H,s)ppm) was obtained.

4th step: 50% of phosphorus oxychloride was added to 19.1 g of 5-(4-hexylphenyl)-2-biracinol and 15.5 g of phosphorus pentachloride, and after stirring at 115°C for 30 minutes, the reaction vessel was sealed. The mixture was stirred at 140° C. for 5 (10) hours. 500g of cooling water and 500g of chloroform
The mixture was poured into a mixture of mA and cooled with ice, and then 11:3 g of ammonia water was added thereto to make it alkaline by adding 50% sodium hydroxide 3202. After removing insoluble matter.

The layers were separated, and the aqueous layer was extracted with chloroform (250×2). The chloroform solutions were combined, dried over sodium sulfate, and then concentrated. The concentrate is silica gel (wakoge/1/C
-200, 300f)) Chromatography failure. Benzene-hexane (1::1) fi [then 2-
(4-hexylphenyl)-5=yellow crystals of chloropyrazine], 0.54 y (mp, 65.0-66.0
°C (after recrystallization with methanol), IRI'KBr)
: 2950, 2915, 2850, 1610°145
5.1325.1135cm-1, NMR (C!DC,
p, 3): 0.89 (3H, t), 1.32-1
．． ．． 65 (8H, m').

2.67 (2H, t), 'i', 8 'i' (
2H,d), 'i', 90 (2H,d).

8.60 (], H, d), 8.75 (lH, d)
ppm) was obtained.

Step 5-1; 5-(4-hexylphenyl)-
2-chloropyrazine'7.51. @, Potassium cyanide 2. '74y, tetrakis triphenylphosphine palladium Pd (PPh, ) 42.3 '77 was added under nitrogen atmosphere to a mixture of dimethylformamide 1.00%
Me was added and heated under rapid flow for 3.5 hours. After cooling, water engineering 00
The extract was dried and concentrated, and the residue was subjected to silica gel (Wako gel C-200,909) column chromatography.Benzene-hexane (4:1) Elongation yielded 4.17y of pale yellow crystals. Recrystallization from methanol gave mp, 8], 5-82.0°C, cp, 5
It became 9.5℃ (TR (KBr): 2950
, 2910.2840°2220.1605,155
5,1505,1465°14.10, 1330c
rn-1-, NMR (○DC13):○, s9 (3
H,t, ).

1.26-1.66 (8H, m), 2.69 (
2)1. t), 7.35 (2H, d), 8°O
O(2H,d), 8.88 (month L6.).

9.10 (1, n, d) ppm) 0 IR in Figure 1
The NMR spectrum is shown in FIG.

[Example 2] 5-(4-n-hexylphenyl)-2-
Production of ethoxypyrazine Step 5-2: Dissolve 0.29 g of metal sulfur and lithium in 20 ml of absolute ethanol, then add 1.33 p of 5-(4-hexylphenyl)-2-chlorohyrazine, and heat under reflux for 1 hour. ~is. After cooling, 100m of saturated salt solution
and extracted with ether (200 tnl x 3). The extract was dried, concentrated, and subjected to silica gel (Wako Gel C-200, 130 g) column chromatography. Developing with benzene-hexane (4:]) gave pale yellow crystals], 22y. Recrystallization with methanol (30 m/) gave white crystals of 5-(4-hexylphenyl)-2-ethoxypyrazine [mp, 54-56°C, IR (KB
r): 2980°2950, 2920. 2
845. 1530. 1,460°1370.1
330.1290.1170z-”, NMR (CDC
l2): 0.88 (3H, t), 1.25~
]-,64゜(llH,m), 2.65(2H,
t, ), 4.41 (2H,q).

7.2 '7 (2H, cl), 'i', 81 (
2H, d), 8.25 (IH, d).

8.46 (LH,a)ppm) was obtained. In Figure 3 I
The R spectrum and the NMR spectrum are shown in FIG.

[Example 3] Melting behavior of a mixed system of 5-(4-hexylphenyl)-2-cyanobi(13) racine and +5-(4-hexylphenyl)-2-ethoxypyrazine in a ratio of 72:28 (mol) The system mixed at mp, 67-70℃, Op, (N#)
63-64°C 5-N It exhibited monotropic liquid crystallinity at 61-62°C.

(Example 4) Production of 5-(4-pentylphenyl)-2-cyanopyrazine Synthesized in the same manner as in Example 1. Properties of the compound are described.

4-pentylacetophenone; bp, 131-133°C
(5 HP) 4-pentylphenylglyoxal hydrate; mp, 8
0-82℃, IR (KBr): 3390, 332
0°2945, 2915, 2845, 1680
, 160.0.1215゜l Co-05, 10104O
1. NMR (DMSO-6,6): 0.8 5
(3H,t), 1.23~]. ,57 (6H,I
TI), 2.63 (2H,N), 5.77
(LH,s), 6.73 (2H,s).

7.33 (2H, d), 8.04 (2H, d,
) pT) m le; mp, 14a5-149.5℃I
R (KBr): '2940゜(14) 2910, 2850, 1665, N
500, 1505.1455°1380.122
5w-' NMR (DMSO-d6): 0.86
(3H,t), 1.25-1.56 (6H
, m), 2.57 (2H,t;).

'7.21 (2H, d), 7%76 (2
H, d), 8.04 (IH, d).

8.1 'i' (lH, (1), 1.2.4
'? (0,7)1. S') ppm gin; mp
, 60.5-61.0℃ IR (KBr): 2950
゜2920, 2850, 1605, 146
0, 11.35cm.

NMR (cpc, i:3); 0.90 (3
H, t, ), 1.33-1.65 (6H, m)
, 2.67 (2H,t)+7.31 (2
H, d).

7.87 (2H, d), 8.60 rlH
, d) , 8. '76 (LH, 6) ppm・mp, 80.5-81.0℃, cp, 60.5
°C, IR (KBr): 2950, 29
20, 2845, 2225.1605°15
55, 1505, 1470, 1320cm
-1HMR (CDC, L,): 0.9 0
(3H, t), Ko,, 3 4 ~ 1.6
6 (6H, m).

2.69 (2H,t), 'i', 36 (
2H,d), 8.00 (2H.

d) , s, s s (LH, d) , 9.1
0 (LH, d) ppm.

[Example 5.6] In the same manner as in Example 2, 5-(4-pentylphenyl)-
2-Ethoxybicidine [mp, 52.51-5'3.
0℃, TR (KBr): 29'40, 2910
, 2840°] -535, 1460, 1365i, 1
330, 1285, 1165゜crn-1, NMR
(CD023)', 0.90 (3)(,t),
1.33-1.65 (9H, m), 2.65
(2H,i), 4.43 (2H,q), 7
．． 2・'7 (2H, d), 7.82 (2H, d
).

8.25 (IH, d), 8.47 (IH, (1
) ppm ) and 5-(4-pentylphenyl)-
2-Butquinhirazine (mp, 45.5-46.0℃
, IR (KBr): 2950°2925, 285
0, 1530, 1460, 1335, 1290
゜11'i'0c1n-1, NMR (CD (43)
: 0.89 (3H, t).

1.00 (3T(,t,), 1.33-1.87
(IOH, m).

2.65 (2H, t), 4.35 (2H, t)
, 7.2'7 (2H, d).

7.81 (2H, d), 8.25 (LH, d)
, 8.47 (LH, d) ppm) was synthesized.

[Example 7] Melting behavior of mixed system A system in which 5-(4-pentylphenyl)-2-cyanopyrazine and 5-(4-pentylphenyl)-2-ethoxypyrazine were mixed at a 68:32 (molar ratio) mp, 6
1-62°C, Q:p, (N-I) 64°C.

5-N Shows liquid crystallinity at 59°C.

(Example 8,] 5- (4-heptylphenyl)
-2-Cyanopyrazine was synthesized in the same manner as in Example 1. Indicates the properties of a compound.

4-hebutylacetophenone; bp 143-145
℃(1ma+Hy).

4-Heptylphenylglyoxal aquarium; mp,
'76.0~78.0℃, IR (KBr): 3
400.

3330, 2945, 2915, 2845, 1
6B5, 160o; 1455, 1225, 110
5 pots.

mp, 139.0-141.0℃, IR(K
Br): 2945, 2910, 2845, 1,
695, 16'? '5, 1605°1510, 1
460, 1380, 1225ctn, NMR (
DMSO-d, ): 0.85 (3H,t),
1.25-1.57 (IOH, m), 2.58
(2H, t), 7.22 (2H, d).

'7.78 (2H, d), 8.03 (IH, d
), 8.12 (LH, d).

12.42 (0.7H, s) ppm.

(17) 5-(4-hebutylphenyl)-2-10 rohirazine;
mp, 565-57.0℃, IR (KBr)
: 2950°2920, 2845, 1605
, 1455 , 1315.1305°1135cm-'
, NMR (ODO!, ): 0.88 (3H
,t).

1.2 El~1.64 (IOH, m), 2.6
6 (2H,z).

7.31 (2H, d), '7.89 (2H, d
), 8.60 (LH, d).

8, '75 (LH, d) pp 0 5-(4-hebutylphenyl)-2-cyanopyrazine;
mp, 78. Temperature 8.5℃, op, (N-I)
68℃, S-N 66.5℃ IR (KBr):
2950, 2910°2B40, 2225, 1
605, 1560, 1510, 1465°141
5, 1330, 1310, 1180, 11
65 cm.

NMR (ODOJ3): 0.88 (3H, t)
, 1.28-1.68 (IoH, m), 2.69
(2H,t,), 7.36 (2H,a).

8.00 (2H, d), 8.89 (LH, d)
, 9.10 (LH, d) ppm.

[Brief explanation of the drawing]

Figure 1 shows the infrared absorption spectrum (KBr method) of 2-(4-n-hexylphenyl)-5-cyanopyrazine obtained in Example 1 of the present invention, and Figure 2 shows the nucleus of the compound (18). Magnetic resonance absorption spectrum (cDc43 solution, 200 MHz). FIG. 3 is an infrared absorption spectrum (KBr method) of 2(4-n-hexylphenyl)-2-ethoxypyrazine obtained in Example 2. Figure 4 shows the nuclear magnetic resonance absorption spectrum (CDC) of the same compound.
4, solution, 200MHz). Patent Applicant Ube Industries Co., Ltd. (19) Procedural Amendment July-2, 1939 Director-General of the Japan Patent Office 1 Indication of Case Patent Application No. 18215-1982 2 Name of Invention Liquid Crystal Pyrazine Derivative 3 Person Making Amendment Relationship to the incident Patent applicant postal code 755 1-12-32 Nishihonmachi, Ube City, Yamaguchi Prefecture Telephone: 03(5)
81) 3311 4 Date of amendment order May 31, 1981 6 Contents of amendment as shown in the attached sheet.

Claims (1)

[Claims] (1) A pyrazine derivative represented by general formula 6, where Rid represents an aliphatic alkyl group having 3 to 9 carbon atoms, and X represents a cyanogen group or an aliphatic alkoxy group having 5 to 5 carbon atoms.