JPH05201881A - Method for rearranging cyclic compound - Google Patents

Abstract

PURPOSE:To obtain the subject method for efficiently producing a trans-isomer benzene derivative by isomerizing a 4-(4'-(trans-4''-alkylcyclohexyl)cyclohexyl) benzene derivative, a 4-(4-alkylcyclohexyl)benzene derivative or a 4-(4'-alkyl-2',6'- dioxyl)benzene derivative, all of which are mixtures of the cis- with the trans- isomers. CONSTITUTION:A 4-(4'-(trans-4''-alkylcyclohexyl)cyclohexyl)benzene derivative, a 4-(4'-alkylcyclohexyl)benzene derivative or a 4-(4'-alkyl-2',6'-dioxyl)benzene derivative, all of which are mixtures of the cis- with the trans-isomers, is subjected to isomerizing reaction in an inert solvent by using a Lewis acid to afford the corresponding trans-isomer benzene derivative.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a 4- (4 '-(trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative, which is a mixture of cis and trans isomers, and 4
The present invention relates to a method for producing a corresponding trans-form benzene derivative by isomerizing a-(4'-alkylcyclohexyl) benzene derivative or a 4- (4'-alkyl-2 ', 6'-dioxyl) benzene derivative.

According to the present invention, 4- (4 '-(trans-4 "-
Alkylcyclohexyl) cyclohexyl) benzene derivative, 4- (4'-alkylcyclohexyl) benzene derivative and 4- (4'-alkyl-2 ', 6'-dioxyl)
The benzene derivative, which has good electrical and optical properties in the trans form, is useful as an intermediate raw material for liquid crystals for display.

[0003]

2. Description of the Related Art 4- (trans-4 '-(trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative, 4- (trans-4'-alkylcyclohexyl) benzene derivative and 4- (trans-
The 4'-alkyl-2 ', 6'-dioxyl) benzene derivative can be produced by separating it from a mixture of cis and trans isomers of the derivative by a method such as recrystallization, distillation or column chromatography. However, each of them has a drawback that the yield is low.

Further, in JP-A-58-189124, 4- (cis-4 '-(trans-4 "-propylcyclohexyl) cyclohexyl) -1-propylbenzene is used as a solvent for N-methylpyrrolidone or dimethylformamide. 4- (trans-4 ′-(trans-4 ″ -propylcyclohexyl) cyclohexyl) -1-propylbenzene was obtained by isomerization with potassium-t-butoxide. However, although this method dilutes potassium-t-butoxide with a solvent,
Because of its low ignition temperature (120 ° C), it is a dangerous reaction.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have found that 4- (4 ′-(trans-4 ″ -alkylcyclohexyl) cyclohexyl) benzene derivative, 4- (4 ′), which is a mixture of cis and trans isomers. -Alkylcyclohexyl) benzene derivative or 4- (4'-alkyl-2 ',
The inventors have earnestly studied a method for obtaining a corresponding trans-form benzene derivative, which is useful as a liquid crystal for display, from a 6'-dioxyl) benzene derivative in a high yield. As a result, as a raw material, each is a mixture of cis and trans isomers.
-(4 '-(trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative, 4- (4'-alkylcyclohexyl) benzene derivative or 4- (4'-alkyl-2', 6'-dioxyl) benzene derivative It was found that a corresponding benzene derivative in the trans form can be obtained in high yield by isomerizing with a Lewis acid in an organic solvent inert to the Lewis acid, and completed the present invention.
As is clear from the above description, the object of the present invention is 4- (4 ′-() which is a mixture of cis and trans isomers.
Trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative, 4- (4'-alkylcyclohexyl) benzene derivative or 4- (4'-alkyl-2 ',
It is intended to provide a method for efficiently producing a corresponding trans-form benzene derivative by isomerizing a 6′-dioxyl) benzene derivative.

[0006]

The present invention includes the following (1) to (1).
It has the configuration of (6).

(1) 4- (4 '-(trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative which is a mixture of cis and trans isomers.

[Chemical 4] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, and X is 1 carbon atom.
~ 9 alkyl group, hydroxyl group, cyano group, alkoxy group having 1 to 9 carbon atoms or halogen group (-F, -C1, -B)
r, -I) and Y are halogen groups or hydrogen atoms (when X is an alkyl group, a hydroxyl group, a cyano group or an alkoxy group,
Y is a hydrogen atom, and when X is a halogen group, Y is a halogen group or a hydrogen atom. ) Represents. ) Is isomerized with a Lewis acid in an organic solvent inert to the Lewis acid. 4- (trans-4 ′-(trans-
Process for producing 4 "-alkylcyclohexyl) cyclohexyl) benzene derivative.

(2) 4- (4'-alkylcyclohexyl) cyclohexyl) benzene derivative which is a mixture of cis and trans isomers.

[Chemical 5] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, and X is 1 carbon atom.
~ 9 alkyl group, hydroxyl group, cyano group, alkoxy group having 1 to 9 carbon atoms or halogen group (-F, -C1, -B)
r, -I) and Y are halogen groups or hydrogen atoms (when X is an alkyl group, a hydroxyl group, a cyano group or an alkoxy group,
Y is a hydrogen atom, and when X is a halogen group, Y is a halogen group or a hydrogen atom. ) Represents. ) Is isomerized with a Lewis acid in an organic solvent inert to the Lewis acid, and a method for producing a 4- (trans-4′-alkylcyclohexyl) cyclohexyl) benzene derivative.

(3) 4- (4'-alkyl-2 ', 6'-dioxyl) benzene derivative which is a mixture of cis and trans isomers.

[Chemical 6] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, and X is 1 carbon atom.
~ 9 alkyl group, hydroxyl group, cyano group, alkoxy group having 1 to 9 carbon atoms or halogen group (-F, -Cl, -B)
r, -I), Y is a halogen group or a hydrogen atom (when X is an alkyl group, a hydroxyl group, a cyano group or an alkoxy group, Y is a hydrogen atom, and when X is a halogen group, Y is a halogen group or a hydrogen atom). There is). ) Is isomerized with a Lewis acid in an organic solvent inert to the Lewis acid, and a method for producing a 4- (trans-4′-alkyl-2 ′, 6′-dioxyl) benzene derivative.

(4) Lewis acid is anhydrous aluminum chloride,
The method according to (1), (2) or (3) above, which is anhydrous aluminum bromide, anhydrous ferric chloride, boron tribromide or zinc chloride.

(5) The amount of the Lewis acid used is 0.1 to 1.0 mol with respect to 1 mol of the cis isomer (1) and (2).
Alternatively, the method described in (3).

(6) An organic solvent inert to Lewis acid is
1,2-dichloroethane, halogenated hydrocarbons exemplified by dichloromethane, toluene, aromatic hydrocarbons exemplified by xylene, aliphatic hydrocarbons exemplified by cyclohexane, hexane, nitrobenzene, or carbon disulfide. The method according to item (1), (2) or (3).

The structure and effect of the present invention will be described in detail below. The isomerization reaction of the present invention is a mixture of 4- (4 ′-(trans-4 ″ -alkylcyclohexyl) cyclohexyl) benzene derivative, which is a mixture of cis and trans isomers,
The 4- (4'-alkylcyclohexyl) benzene derivative or 4- (4'-alkyl-2 ', 6'-dioxyl) benzene derivative is dissolved or suspended in an organic solvent which is inert to Lewis acid, and Lewis acid is present. It is performed by stirring under.

As the benzene derivative used in the present invention,
Specific examples thereof include, but are not limited to, the following. That is, 4- (4 '-(trans-4 "-propylcyclohexyl) cyclohexyl) -1-propylbenzene, 4- (4'-(trans-4" -propylcyclohexyl) cyclohexyl) -1-methoxybenzene, 4- (4 '-(Trans-4 "-propylcyclohexyl) cyclohexyl) -1-fluorobenzene,
4- (4'-propylcyclohexyl) -1-hydroxybenzene, 4- (4'-propyl-2 ', 6'-dioxyl)
-1-cyanobenzene, 4- (4 '-(trans-4 "-ethylcyclohexyl) cyclohexyl-1-iodobenzene, 4- (4'-pentylcyclohexyl) -1,2-difluorobenzene, 4- (4"-propyl-2', 6 '-
Dioxyl) -1-ethoxybenzene.

Examples of the Lewis acid used in the present invention include anhydrous aluminum chloride, anhydrous aluminum bromide, anhydrous ferric chloride, boron tribromide and zinc chloride, preferably anhydrous aluminum chloride and anhydrous aluminum bromide. Is.

The amount of the Lewis acid used is 0.1 to 1.0 mol with respect to 1 mol of the cis isomer, and preferably 0.4 to 0.6 mol from the viewpoint of reaction rate. If the amount of Lewis acid used is less than 0.4 mol, the catalyst will be rate-determining and the reaction time will be 2
It becomes 4 hours or more, which is not practical, and when the amount of Lewis acid used exceeds 1.0 mol, decomposition reaction of the raw material occurs. It is presumed that one molecule of Lewis acid forms a sandwich-type structure complex with two molecules of cis isomer to perform isomerization reaction.

As the solvent used for the isomerization reaction, 1,2-dichloroethane, which is inert to Lewis acids, halogenated hydrocarbons such as dichloromethane, aromatic hydrocarbons such as toluene and xylene, or cyclohexane or methyl are used. Mention may be made of cyclohexane, aliphatic hydrocarbons such as hexane, or nitrobenzene, or carbon disulfide.

The reaction liquid obtained from the isomerization reaction is purified by a conventional method. That is, 1 to 10N hydrochloric acid having a volume of 2 to 3 times is gradually dropped into the reaction solution to decompose the Lewis acid,
Then, extraction is performed with a non-water-soluble organic solvent such as toluene or benzene. After extraction, the extract is washed with an aqueous sodium hydrogen carbonate solution and then washed with water. After washing with water, the solvent is removed by vacuum distillation to obtain a trans-form benzene derivative.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Example 1 4- (4 '-(trans-4 "-propylcyclohexyl) cyclohexyl) -1-propylbenzene (cis isomer 49WT%, trans), which is a mixture of cis and trans isomers, was placed in a 500 ml three-necked flask. Body 51WT%) 100g
(0.307 mol) and 1,2-dichloroethane 250
Add ml and stir at 15 ° C to stabilize the temperature, and then add 20.4 g (0.153 mol) of granular anhydrous aluminum chloride.
Was added, and the mixture was stirred at 15 ° C for 40 minutes. After 40 minutes, about 1 ml of the reaction solution was sampled, and 2 ml of 6N-HCl was added to decompose the aluminum chloride. After decomposition, 2 ml of toluene was added for extraction, and the extract was subjected to liquid chromatography (column: YMC Packed Co).
lumn Type A-302 ODS, mobile phase: M
The analysis was carried out with eOH = 7: 3). As a result, cis isomer: trans isomer = 5 WT%: 95 WT%. After analysis, 6
N-HCl (500 ml) was slowly added dropwise to carry out crystallization.
After crystallization, 500 ml of toluene was added and well stirred, and then transferred to a separating funnel to separate the toluene layer. The toluene layer is
After washing with sodium hydrogen carbonate and water in this order, the solvent was distilled off to obtain a concentrate. Next, the concentrate was dissolved in a mixed solvent of heptane and ethanol and recrystallized to give 4- (trans-4 '-(trans-4 "-propylcyclohexyl) cyclohexyl) -1-propylbenzene (having a gas chromatographic purity of 99.4%. 63 g of 100% of trans form was obtained.

Example 2 The procedure of Example 1 was repeated, except that the starting materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4 '-(trans-4 "-propylcyclohexyl) cyclohexyl) -1-methoxybenzene Lewis acid Anhydrous aluminum chloride Solvent 1,2-dichloroethane Temperature 15 ° C Reaction time 1 hour Transfer rate 95%

Example 3 Example 3 was carried out in the same manner as in Example 1 except that the raw materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4 '-(trans-4 "-propylcyclohexyl) cyclohexyl) -1-fluorobenzene Lewis acid Anhydrous aluminum chloride Solvent 1,2-Dichloromethane Temperature 15 ° C Reaction time 2 hours Transfer rate 90%

Example 4 The procedure of Example 1 was repeated, except that the starting materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4'-propylcyclohexyl) -1-
Hydroxybenzene Lewis acid Anhydrous aluminum chloride Solvent Toluene Temperature 60 ° C Reaction time 7 hours Transition rate 93%

Example 5 Example 5 was carried out in the same manner as in Example 1 except that the raw materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4'-propyl 2 ', 6'-dioxyl)-
1-cyanobenzene Lewis acid, anhydrous aluminum chloride, solvent 1,2-dichloroethane temperature 15 ° C reaction time 1.5 hours transfer rate 80%

Example 6 Example 6 was carried out in the same manner as in Example 1 except that the raw materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4 '-(trans-4 "-ethylcyclohexyl) cyclohexyl) -1-iodobenzene Lewis acid Anhydrous aluminum bromide Solvent Cyclohexane Temperature 60 ° C Reaction time 8 hours Transfer rate 90%

Example 7 Example 1 was repeated except that the starting materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4'-pentylcyclohexyl) -1,
2-Difluorobenzene Lewis acid, anhydrous aluminum bromide, solvent, toluene, temperature 60 ° C, reaction time 10 hours, transfer rate 80%

Example 8 Example 8 was carried out in the same manner as in Example 1 except that the starting materials, the types of Lewis acid and solvent, and the reaction conditions were as follows. as a result,
The following transfer rates were obtained. Raw material 4- (4'-propyl ', 6'-dioxyl) -1
-Ethoxybenzene Lewis acid Anhydrous aluminum bromide Solvent 1,2-Dichloroethane Temperature 15 ° C Reaction time 2.0 hours Transfer rate 85%

[0028]

The effects of the present invention are as follows: 4- (4 '-(trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative, which is a mixture of cis and trans isomers, 4- (4'-alkylcyclohexyl) benzene Derivative or 4- (4'-alkyl-2 ', 6'-dioxyl)
By isomerizing a benzene derivative with a Lewis acid in an organic solvent that is inert to the Lewis acid, a corresponding trans-form benzene derivative useful as an intermediate raw material for a liquid crystal for display can be efficiently and safely produced. I was able to provide a method.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C07C 13/28 8619-4H 25/18 9280-4H 37/48 9159-4H 39/17 9159-4H 41/32 43/21 8619-4H 255/50 6917-4H // C07B 61/00 300 C07D 319/06 (72) Inventor Yasuhiro Fukui 2126-2 Kamagiya-cho, Kanazawa-ku, Yokohama-shi, Kanagawa

Claims (6)

[Claims] 1. A mixture of cis and trans isomers 4.
-(4 '-(trans-4 "-alkylcyclohexyl) cyclohexyl) benzene derivative. (In the formula, R is an alkyl group having 1 to 9 carbon atoms, and X is 1 carbon atom.
~ 9 alkyl group, hydroxyl group, cyano group, alkoxy group having 1 to 9 carbon atoms or halogen group (-F, -C1, -B)
r, -I) and Y are halogen groups or hydrogen atoms (when X is an alkyl group, a hydroxyl group, a cyano group or an alkoxy group,
Y is a hydrogen atom, and when X is a halogen group, Y is a halogen group or a hydrogen atom. ) Represents. ) Is isomerized with a Lewis acid in an organic solvent inert to the Lewis acid. 4- (trans-4 ′-(trans-
Process for producing 4 "-alkylcyclohexyl) cyclohexyl) benzene derivative. 2. A mixture of cis and trans isomers 4.
-(4'-alkylcyclohexyl) benzene derivative. [Chemical 2] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, and X is 1 carbon atom.
~ 9 alkyl group, hydroxyl group, cyano group, alkoxy group having 1 to 9 carbon atoms or halogen group (-F, -C1, -B)
r, -I) and Y are halogen groups or hydrogen atoms (when X is an alkyl group, a hydroxyl group, a cyano group or an alkoxy group,
Y is a hydrogen atom, and when X is a halogen group, Y is a halogen group or a hydrogen atom. ) Represents. ) Is isomerized with a Lewis acid in an organic solvent which is inactive to the Lewis acid, and a method for producing a 4- (trans-4′-alkylcyclohexyl) benzene derivative. 3. A mixture of cis and trans isomers 4.
-(4'-alkyl-2 ', 6'-dioxyl) benzene derivative. [Chemical 3] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, and X is 1 carbon atom.
~ 9 alkyl group, hydroxyl group, cyano group, alkoxy group having 1 to 9 carbon atoms or halogen group (-F, -C1, -B)
r, -I) and Y are halogen groups or hydrogen atoms (when X is an alkyl group, a hydroxyl group, a cyano group or an alkoxy group,
Y is a hydrogen atom, and when X is a halogen group, Y is a halogen group or a hydrogen atom. ) Represents. ) Is isomerized with a Lewis acid in an organic solvent inert to the Lewis acid. 4- (trans-4′-alkyl-)
A method for producing a 2 ', 6'-dioxyl) benzene derivative. 4. The Lewis acid is anhydrous aluminum chloride, anhydrous aluminum bromide, anhydrous ferric chloride, boron tribromide or zinc chloride, (1), (2) and (3).
The method described in. 5. The method according to claim 4, wherein the amount of the Lewis acid used is 0.1 to 1.0 mol with respect to 1 mol of the cis isomer. 6. The Lewis acid-inert organic solvent is halogenated hydrocarbon, aromatic hydrocarbon, alicyclic hydrocarbon, nitrobenzene or carbon disulfide (1),
The method according to (2) and (3).