JPS6048492B2 - Method for producing polyhydric phenols and phloroglucin - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing polyhydric phenols.

More specifically, the present invention provides compounds of the general formula (wherein R represents a lower alkoxy group) and phloroglucin (P
hlOrOglucinOl).

The process provided by the present invention comprises heating a compound of the general formula (wherein R has the same meaning as defined above) with an alkali metal lower alcoholate and, if necessary, preparing the compound according to methods known per se. - Characterized by the conversion of the product compound of formula 1 to phloroglucin by Therru cleavage.

Examples of lower alkoxy represented by R include methoxy and ethoxy, with methoxy being preferred.

Alkali metal lower alcoholates are conveniently derived from lower alkanols such as methanol, ethanol, isopropanol and tert-butanol, (lower alkoxy)mono-lower alkanols such as ethoxyethyl alcohol or benzyl alcohol. As the alkali metal lower alcoholates, alkali metal lower alcoholates and isopropylates are preferred. This alkali.
The metal may be lithium, sodium or potassium, with lithium or sodium being preferred. The lower alkoxy groups and lower alkanols mentioned above contain up to 7 carbon atoms.

Heating the compound of formula (1) with the alkali metal alcoholate is conveniently carried out at 80°C to 200°C.

This temperature range is preferably 110°C to 150°C.
Heating of the compound of formula (1) with an alkali metal alcoholate can be carried out in the presence or absence of a solvent.

Examples of suitable solvents used include aliphatic hydrocarbons (e.g. ligroin, paraffins, terpene hydrocarbons, etc.), aromatic hydrocarbons (e.g. benzene, toluene, xylene, etc.), ethers (e.g. dioxane, etc.). , tetrahydrofuran, dimethoxyethane, etc.) and alcohols (eg, ethanol). Preferred solvents are toluene, xylene and isopropanol. Heating the compound of formula (1) and the alkali metal alcoholate is conveniently carried out under an inert gas atmosphere (for example under nitrogen or argon).

5 The molar ratio of the compound of formula (1) and the alkali metal lower alcoholate is conveniently from 2:5 to 1:5.

Particularly when the alcoholate group is sterically small, i.e.
When sodium methylate, sodium ethylate, etc. are used as the alkali metal alcoholate, the formula
During heating of the compound and the alkali metal alcoholate, the ether group R can be replaced by the alcoholate group by a vinylogue reaction. Isolation of the compound of the formula I from the mixture obtained after heating of the compound of the formula Π and the alkali metal lower alcoholate can be carried out by methods known per se, for example by dissolving the above mixture in water and acidifying it. This can then be carried out by extraction with a solvent (eg chloroform or ether).

The conversion of compounds of formula I to phloroglucin can be carried out by methods known per se for acidic ether cleavage, for example using hydrohalic acids [A. Mc. Klilup, S.
ynth. [Prey, Ch.
em. Ber. 74l2l9, l222 (1941)].

Insofar as the starting material of formula (2) is unknown, it can be prepared by methods known per se.

The invention is illustrated by the following examples.

Example 1 (a) Triacetic acid δ-lactone methyl ether of 5y and 9
．． 7 Da of powdered sodium ethylate are suspended in 100 mι of xylene and the suspension is kept under stirring at reflux temperature under a nitrogen atmosphere for 3 hours.

After cooling, the mixture is added to 200 ml of water and then extracted with ether. The aqueous phase is acidified and extracted three times with methylene chloride. The combined methylene chloride phases are dried over sodium sulfate and then condensed. Thus, 5.5 Da of semi-crystalline material containing phloroglucin monoethyl ether (yield 79%) in addition to solvent residues is obtained. This NMR (nuclear magnetic resonance) is (DMSO,・
60MHz) 3.61/S3H (0CH.), 5.82
/Sb,3H (aromatic H), 9.2/Sb2H(CH)
It is. Similar results are obtained if naphthalene or cymene is used instead of xylene and/or lithium ethylate is used instead of sodium ethylate as solvent. (b) 2y Phloroglucin monoether ether is stirred in 100 ml of concentrated hydrochloric acid (35%) at room temperature for 2 days.

The mixture was then partially neutralized (PH 2-3) with an aqueous sodium carbonate solution, the precipitated sodium chloride was filtered off, and the filtrate was filtered with 150 mI of ether.
Extract 1811 Terama in an r-Steudel type extractor. The ether extract is dried over sodium sulfate and concentrated to yield 1.4y to 1.55y phloroglucin (86% to 95%) with a melting point of 209° to 210°C after recrystallization from water. . Triacetic acid δ-lactone methyl ether used as a starting material is produced as follows.

144y triacetic acid lactone [N, Colle, J.
Chem. SOc. 59, 6O7 (1891)] and 8
0y of anhydrous sodium carbonate is suspended in 1.41% of acetone and this suspension is heated under reflux with 144y of dimethyl sulfate for 2 hours.

The solution is cooled, filtered, extracted with 500 mt of acetone and concentrated. The crystalline crude product obtained is recrystallized from 300 ml of water and dried in vacuo. 120y triacetic acid δ-lactone methyl ether (75%) having a melting point of 87°-88°C is obtained.

If the above operation is performed using diethyl sulfate instead of dimethyl sulfate, triacetic acid δ-lactone methyl ether will be obtained.

Example 2 3.2y of sodium at reflux temperature 10077! 1 of isopropanol for 2 hours.

5y triacetic acid δ-lactone methyl ether is then added. The solvent is distilled off and the solid residue is heated to 185°C for three more cycles. After cooling, the mass is dissolved in 175 ml of water, acidified and extracted three times with 100 ml of ether each time. The combined and dried ether portions were concentrated to give a 5.99% viscosity containing 77% of an approximately 1:1 mixture of phloroglucin monoether and phloroglucin monoisopropyl ether (83% yield). You will get a small oily substance. Benzene/5 for each component
% ether by chromatography on silica gel. NMR (monomethyl ether): Same as NMR data in Example 3 below.

NMR (monoisopropyl ether): (DMSO, 6OMHz), 1.20/doublet (DOu
blet) 6H (isopropyl group), 4.43/Heptet IH (methane), 5.90/Sb3H
(Aromatic H), 9.2/Sb2H(0H) The mixture of ethers obtained in the above section can be converted into phloroglucin by the operation described in part (b) of Example 1.

The same mixture of ethers obtained according to the first section of this example was prepared by mixing 11.4 das sodium isopropylate and 5y triacetic acid delta-lactone methyl ether with 10
It can be obtained when suspending in 0 mι of tetrahydrofuran and then heating the mass obtained after concentration to 185° C. for 30 minutes.

Example 3 8y of sodium was suspended in 100 mι of 2-ethoxyethanol and the mixture was then concentrated under high vacuum to 0.04 T0rr. Dry at 140°C.

The resulting 16.3 g (145 mm01) of sodium 5m salt was suspended together with 5y (35.7 mm01) of triacetic acid δ-lactone methyl ether in 100 ml of xylene, and the suspension was then placed under a nitrogen atmosphere. Keep under reflux for 3 hours. The mixture is cooled and extracted with 200 ml of water, and the aqueous phase is then washed twice with ether. It is then acidified to PH2 and extracted three times with methylene chloride. After concentrating this methylene chloride phase, 3.9 Da (78%) of phloroglucin monomethyl ether are obtained. This NMR (nuclear magnetic resonance) is (DMSO
, 60N4Hz) 1.27/Ξ heavy line (Tripiet)
3H (J = 3.5Hz) (ethyl group), 3.90/
Quartet 2H (J = 3.5Hz) (
oxymethylene), 5.84/Sb3H (aromatic H),
9.2/Sb2H (0H). Similar results (70% yield) are obtained when sodium benzyl alcoholate is used instead of sodium 2-ethoxyethanolate. The conversion of the monomethyl ether to phloroglucin can be carried out by a method similar to that described in part (b) of Example 1.

Example 4 23.8y of propargyl bromide are added dropwise into 120mt of dimethyl sulfoxide containing 10y of triacetate lactone and 10y of sodium carbonate under cooling, and the mixture is then stirred for 2 hours at room temperature.

The mixture is dissolved in ether and washed three times with water. The flocculent precipitate is filtered off and the ether phase is dried over sodium sulfate and then concentrated. The filtrate (4.7y) and the residue (6.1y) have a melting point of 150° to 151°C) yield of 8
It turns out to be 3% pure triacetic acid lactone 3-propargyl ether. Triacetic acid 3-C-benzyl ether (melting point 91.5° to
2°C).

39 triacetic acid lactone 3-0-benzyl ether to 2
．． 60 mι with 9 Da (4 equivalents) of lithium ethylate
of cumene and the mixture is refluxed for 4 hours.

Claims (1)

[Claims] 1. General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R represents a lower alkoxy group) A method for producing a compound represented by the general formula (I) (wherein R represents a lower alkoxy group) II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ The compound of the above formula (I) characterized in that the compound of (II) (in the formula R has the same meaning as above) is heated with an alkali metal lower alcoholate. Production method. 2. The method of claim 1, wherein the compound of formula (II) is heated with an alkali metal lower alcoholate at a temperature of 80°C to 200°C. 3. The method of claim 1, wherein the molar ratio of the compound of formula (II) to the alkali metal lower alcoholate corresponds to 2:5 to 1:5. 4 A method for producing phloroglucinol, which has the general formula ▲
There are mathematical formulas, chemical formulas, tables, etc.▼The formula that is produced when the compound (II) (in the formula R represents a lower alkoxy group) is heated with an alkali metal lower alcoholate▲There are mathematical formulas, chemical formulas, tables, etc.▼(Formula A method for producing phloroglucin, which comprises ether-cleaving a compound (wherein R has the same meaning as above) by a method known per se to produce phloroglucin. 5. The method of claim 4, wherein the compound of formula (II) is heated with an alkali metal lower alcoholate at a temperature of 80°C to 200°C. 6. The method of claim 4, wherein the molar ratio of the compound of formula (II) to the alkali metal lower alcoholate corresponds to 2:5 to 1:5.