JPH0243388A - Method for producing 4,4'-dihydroxybiphenyls - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for electrolytically producing di-, dihydroxybiphenyls.

ta,q'-dihydroxybiphenyls are useful as bactericidal agents, synthetic intermediates, antioxidants, and the like.

For example, 3.3', 3.3'-tetra substituted p, +'
-Dihydroxybiphenyl is used in fats, oils, gasoline, lubricating oils,
Used to stabilize rubber compositions, etc.

[Conventional technology]

<z4'-Dihydroxybiphenyls have been produced by, for example, the following methods.

■ Manganese(III) -y for alkylphenols
Oxidative coupling with cetyl acetonate salt +, lI
'-Method for obtaining dihydroxybiphenyls (J, Am
, Chem, Soc, , qo, q/3q(
/qt, g), ), ■ 2. A method for obtaining ri'-dihydroxybiphenyls by oxidizing A-di-t-butylphenol with oxygen in the presence of caustic potassium, converting a portion to diphenoquinones, and heat-treating the reaction mixture at high temperature (% --ooq3s), ■ A method for obtaining 'x, <z'-dihydroxybiphenyls by oxygen oxidation of alkylphenols in the presence of a copper compound and a boron compound (JP-A No. 2003-32333), ■ Halogenation A method of removing and dimerizing phenol using a catalyst such as palladium or nickel (Japanese Patent Application Laid-open No. 5
6-s3t, :tl),■p,tl-bis(ll-
Method for obtaining +,lI'-dihydroxybiphenyl by subjecting cyclohexanol (hydroxyphenyl) to decomposition and dehydrogenation reaction (JP-A-3-λq3g), (1), 2. A method for obtaining p,<z'-dihydroxybiphenyls by electrolytic camping reaction of A-dimethylphenol in acetonitrile (Electrochemistry and Industrial Physical Chemistry, ys, /3o(/qqq),).

[Problems to be Solved by the Invention] However, each of these conventional methods has the following drawbacks.

That is, the above method (1) requires more than the necessary amount of expensive reagents, and the reaction results are also unsatisfactory.

In method (1) above, there are restrictions on the alkylphenols that can be applied and harsh conditions are required, resulting in poor purity of the product and poor reaction results.

In the method (2) above, there are restrictions on the alkylphenols that can be applied, and furthermore, it requires complicated operations.

Method (1) above requires high temperatures and has poor reaction results.

In method (2) above, raw materials are expensive and moreover, multi-step synthesis operations are required.

In method (1) above, the reaction results are extremely poor and many by-products are produced.

Thus, it cannot be said that an industrially advantageous manufacturing method for +,+'-dihydroxybiphenyls has yet been established, and 9. It has been desired to develop a method for producing lI-' dihydroxybiphenyls.

[Failure to solve the problem]

The present inventors have solved the problems of the conventional method described above.
The present invention has been completed as a result of intensive studies aimed at developing an industrially advantageous method for producing lI'-dihydroxybiphenyls.

That is, the present invention provides general formula (I): (wherein, R1 and R2 represent an alkyl group having /~/2 carbon atoms and may be different from each other; R3 and R4 represent an alkyl group having /~/2 carbon atoms; g,ll'-dihydroxybiphenyls, which are characterized in that alkylphenols represented by (representing an alkyl group or a hydrogen atom and which may be different from each other) are electrolytically trimerized in one step in a non-diaphragm electrolytic cell. The gist is manufacturing/method.

The present invention will be explained in more detail below.

The alkylphenols used in the method of the present invention have the general formula (
I): (In the formula, R and R2 represent an alkyl group having carbon number/~7.2 and may be different from each other. Also, R3 and R4
represent an alkyl group having 7.2 carbon atoms or a hydrogen atom, and may be different from each other. ), O-dialkylphenol, 2,3° O-trialkylphenol, and tetraalkylphenol. Examples of the alkyl group include those having a straight chain or a side chain having 1 to 2 carbon atoms, and preferably an alkyl group having 1 to 2 carbon atoms. In particular, t-butyl group is most preferred.

Examples of the above 2,A-dialkylphenol include Eva λ
, O-dimethylphenol tylphenol, λ, A-diisopropylphenol, co, A-di5ec-butylphenol, co, otsu-dit
-Pythyl phenol-natonaka is getting worse. As for the above-mentioned 3,6-drialkylphenol, for example,
3. O-trimethylphenol, λ, 3. Examples include O-t-di-triethylphenol, Ot-t-butyl-3-methylphenol, 2.3-diethyl-A-1-butylphenol, and the like. Examples of the above-mentioned 6-titraalkylphenols include 2, 3, and 6-thitraalkylphenols. Left, 6-tetramethylphenol, 2,3. ! -) Remethyl Otsu-1
-butylphenol, 2,6-sheet t-butyl-3,S-
Examples include dimethylphenol. Among these, KO, O-diisopropylphenol or λ, A-di-t
-butylphenol is preferably used.

In the method of the present invention, the above-described electrolytic trimerization reaction of alkylphenols is carried out in a membraneless electrolytic cell. That is, an electrolytic cell is used that does not have a diaphragm that separates the tank chamber into a cathode chamber and an anode chamber.

The solvent used in the electrolytic trimerization reaction of the present invention is preferably a lower aliphatic alcohol, and more preferably a mixed solution of the lower aliphatic alcohol and an organic solvent that is miscible with the lower aliphatic alcohol.

The lower aliphatic alcohol is preferably an alcohol having a carbon number of 1 to q, and examples thereof include methanol, ethanol, isopropanol, and t-butyl alcohol. The organic solvent that is miscible with the lower aliphatic alcohol may be either a hydrophilic organic solvent or a hydrophobic organic solvent. Specific examples of the hydrophilic organic solvent include acetonitrile, tetrahydrofuran, dimethylformamide, etc.; Specific examples include halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, and dichloroethane, and aliphatic or alicyclic hydrocarbons such as pentane, hexane, and cyclohexane.

As the solvent for the method of the present invention, a mixed solution of methanol and methylene chloride gives particularly favorable results.

The mixing ratio of the lower aliphatic alcohol and the organic solvent has a remarkable effect on reaction results such as product selectivity, yield, and conversion rate of reaction raw materials. It is preferable to use the capacitance ratio in a range of usually 9/1 to 1/9, preferably 5/1 to 1/3.

The amount of the solvent used is not particularly limited, and is appropriately determined depending on the reaction conditions and the like.

The concentration of alkylphenols in the solvent is not particularly limited, but from the viewpoint of reaction efficiency, a higher concentration of alkylphenols is preferable.

Various salts can be used as supporting electrolytes in the method of the present invention. The cation moiety of the above salt includes, for example, an alkali metal cation such as sodium (Na), lithium (L1+), potassium (K+); magnesium (
Mg2+), calcium (Ca2+), barium (Ba
2+); or substituted or unsubstituted ammonium ions represented by the general formula (■): (wherein R5, R6, Rt and R8 are hydrogen atoms or alkyl groups), etc. can be mentioned.

In addition, as the anion moiety of the above salt, for example, perchloric acid (
CIC): ), fluoroboric acid (BFυ), sulfonic acids such as p-toluenesulfonic acid (C) (3C61 (, SO3)), and anions such as sulfuric acid (804'-).

The concentration of the supporting electrolyte is usually 0.0/~! ;, O
M is used in the range of 0.0M, and preferably about 0.0M to 7.0M.

The electrode material used in the electrolytic trimerization reaction of the method of the present invention is not particularly limited, and known materials used in ordinary electrolytic reactions can be used.

As materials for the cathode and anode, for example, platinum, carbon, lead oxide, lead, Francie carbon, stainless steel, nickel, aluminum, zinc, and other processed electrodes can be used.

The reaction temperature should normally be 100°C or less, but is preferably in the range of -20°C to SO°C.

In the electrolytic trimerization reaction in the method of the present invention, the current density can be selected within the range of 0.07 to 3 OA/d-, but preferably θ, 0 to θ/dn? It is.

Further, the amount of electricity applied is usually /~20 faradays, preferably /~6 faradays per mole of the alkylphenol.

The electrolytic trimerization reaction may be carried out either in air or in an inert gas atmosphere, and is not particularly limited, but the electrolytic reaction in an inert gas atmosphere gives better results.

Further, the reaction time is appropriately selected depending on the concentration of reaction raw materials, current density, solvent, composition, and other reaction conditions.

〔Example〕

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited by the Examples unless it exceeds the gist thereof.

Example/2. Otsu-di-t-butylphenol (hereinafter referred to as DBP) 2
0 my (/, o mmol), lithium perchlorate 3217 mg (3,0 mmol), methanol? , G, and methylene chloride, 2, were added.

A pair of platinum electrode plates (
λαX 3 crn) was attached, cooled on ice, and the current density o
, ;a A/am' (terminal voltage 2 to 3 ■), constant current electrolysis was performed. The electrolytic reaction was continued until an amount of electricity of 3.5 faradays was applied to 1 mole of DBP. Analysis of the reaction product revealed that the conversion rate of the raw material DBP was g q
,g%,v,<z'-dihydroxy-3,! ;, 3',
s'-tetra-t-butylbiphenyl (hereinafter referred to as TBBP)
What is the selection rate of )? /, 3%. 3. ! ;
,3',! No '-tetra-t-butyl-diphenoquinone was detected.

Examples 2 to 3 The reaction was carried out in the same manner as in Example 1 except that the mixing ratio of methanol and methylene chloride was changed as shown in Tables 1 to 3. The results are shown in Table/.

Examples B to G Reactions were carried out in the same manner as in Example 1, except that the electrode plate (6crn2) shown in Table 3 was used as the cathode and anode instead of the platinum plate electrode. The results are shown in Table-3.

Examples G to S In Examples 1 and 3, each of the supporting electrolytes shown in Table 1 was used instead of lithium perchlorate. The reaction was carried out in the same manner except that θmmol was used.

The results are shown in Table-C.

*1) Tetraethylammonium p-)luenesulfonate [Effects of the invention] According to the method of the present invention, easily available alkylphenols are used as starting materials and directly produced as organic synthesis intermediates through a simple one-step electrolytic reaction. Important t,ll'-dihydroxybiphenyls can be efficiently produced with high purity under mild conditions.

Therefore, the industrial utility of the present invention is extremely high.

Claims (2)

[Claims] (1) General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(I) (In the formula, R_1 and R_2 represent an alkyl group having 1 to 12 carbon atoms, and even if they are different from each other) In addition, R_3 and R_4 represent an alkyl group having 1 to 12 carbon atoms or a hydrogen atom, and may be different from each other.) The alkylphenols represented by R_3 and R_4 represent an alkyl group having 1 to 12 carbon atoms or a hydrogen atom, and may be different from each other. A method for producing 4,4'-dihydroxybiphenyls, characterized by: (2) In the method for producing 4,4'-dihydroxybiphenyls according to claim 1, the electrolytic dimerization reaction is carried out using (i) a lower aliphatic alcohol, or (ii) an organic solvent that is miscible with the lower aliphatic alcohol, and a lower aliphatic alcohol. A method characterized in that it is carried out in a mixture with an aliphatic alcohol.