CS198129B2 - Method of preparing pyrocatechol ethers - Google Patents

Abstract

1457108 Preparation of pyrocatechol derivatives BASF AG 24 Oct 1973 [25 Oct 1972] 49404/73 Heading C2C Pyrocatechols ethers of formula where R denotes alkyl which may be substituted by halogen, alkenyl which may be substituted by halogen, alkynyl which may be substituted by halogen, or aralkyl are obtained by cleaving in an acid medium a compound of formula where R has the above meaning and R<SP>1</SP> denotes H or (C 1-4 ) alkyl; R<SP>2</SP> denotes H, benzyl, (C 1-4 ) alkyl which may be substituted with halogen, -OCH 3 or -OC 2 H 5 ; R<SP>3</SP> denotes (C 1-4 ) alkyl, cycloalkyl, #-chloroethyl, alkoxyalkyl, phenyl, (C 2-4 ) alkenyl, (C 2-4 ) alkynyl, or acyl or R<SP>1</SP> and R<SP>2</SP>, together with the carbon atoms whose substituents they are, and R<SP>1</SP> and R<SP>3</SP>, together with the carbon and oxygen atom whose substituents they are, form a 5- or 6-membered ring. The invention also comprises compounds of Formula II wherein R, R<SP>1</SP>, R<SP>2</SP> and R<SP>3</SP> have the meanings given above with the proviso that when R is methyl, R<SP>1</SP> and R<SP>2</SP> are not simultaneously hydrogen.

Description

The invention relates to a valuable novel process for the preparation of pyrocatechin ethers.

It is known that pyrocatechin derivatives, in particular pyrocatechin ethers, can be prepared by the following methods:

Partial etherification of pyrocatechin (J. Chem. Soc. 1927, 1664; U.S. Pat.

202,573); diazotization of o-aminophenylalkyl ethers (DAS 1 543 573) or dehydrogenation of monoenol ethers of 1,2-cyclohexanedione with sulfur at a temperature of 200 to 300 ° C (DOS 1 917 602).

The process starting from pyrocatechin has the disadvantage that losses of pyrocatechin and the alkylating agent occur due to the formation of bisethers. The other two processes are partly technically expensive as they represent multi-stage syntheses with air pollution problems and waste water costs. In particular, the known processes fail in the case of reactive radicals R, in which other reactions (cyclization and addition reactions) also take place under the reaction conditions.

It has now been found that the pyrocatechin ethers of the formula I can be prepared in a simple manner with excellent yield

OR (I) wherein

R is alkyl, alkenyl or alkynyl having up to 4 carbon atoms and optionally substituted by halogen, or benzyl when the pyrocatechin derivative of formula II

OR (A | -OC -OR ³ UL ....

where R is as defined above,

R ¹ is hydrogen or alkyl having 1 to 4 carbon atoms,

R2 is hydrogen or optionally halogen, methoxy or ethoxy substituted C1-C4 alkyl or benzyl,

R ³ is alkyl of 1 to 4 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, (-chloroethyl, methoxyethyl, alkenyl or alkynyl of up to 4 carbon atoms, acetyl or propionyl; and

R @ ² and R @ ² optionally form together with the carbon and oxygen atoms to which they are attached a five or six membered ring, cleaving in an acidic medium, for example by treatment with aqueous acid or by exchange with lower alcohols with 1 to 5. carbon atoms or phenols under acidic catalysis, at a temperature of 40 to 100 ° C.

Cleavage can be represented by the following equation:

For example, the starting compound is mixed in a strongly diluted, for example, 0.001% (w / w) aqueous mineral acid, such as sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid, until cleavage. Optionally, water-miscible organic solvents which increase the solubility of the starting compounds (e.g., alcohols, ketones, ethers) may also be used in an amount of 0.1 to 90% (w / w).

%] of the mixture. Thus, the monoethers of the pyrocatechin of the formula can be prepared

OH .....

OR shown in the following table:

СНз

C2H5 ‘

П-С3Н7

C-H7-CH2-CH = CH2

CH3

From —CH \

CH = CH 2 - CH 2 - CH = CH - CH 3 - CH 2 - CH = CC 1 - CH 3

H

From —CH2 — C = C

I \

Cl Cl —CH2 — C = CCl2

AND

CHs

tv; tt; n _D 25

t. 3.3 kPa - = 105 ° C t. 2.7 kPa = Mp 100 ° C t. 1.9 kPa - Mp 110-114 ° C t. -26.7 Pa - = 66 ° C t. 1.6 kPa = Mp 110 ° C

t -v. -53.3-Pa = 68 to 74 ° C nD25 = 1.4875 nD25 = 1.5295 nD25 = 1.5027 —CHž — C = CH — CHž — С-С — СИз —CHz — C = C — CžH5

mp = 49 to 50 ° C mp = 44 to 47 ° C nD25 = 1.5360

R tv; tt; n _D ²⁵

CH 3 / - CH mp 52-53 ° C;

C = CH

The invention is illustrated by the following examples.

Example 10 o- (1-butin-3-yloxy) -phenol

220 mass,. parts of O- (L-methoxyethoxy) phenyl- (l-butyn-3'-yl) ether was slowly added dropwise to the boiling and the well-stirred mixture 2,000 weight, of water, _500: wt, parts of ethanol and 2 wt. parts of concentrated sulfuric acid. The reaction mixture is heated at reflux for a further two hours, cooled and extracted three times with 150 parts by weight of chloroform. After drying over sodium sulfate, the solvent was evaporated and the residual oil crystallized on standing. Yield 126 parts by weight of product, mp 52-53 ° C. The compound is uniform by thin layer chromatography.

Example 2 o-10-propoxyphenol

Using the procedure of Example 1, 209 parts by weight of o- (1-methoxy-ethoxy) -phenylisopropyl ether were hydrolyzed. Yield 149 parts by weight of product at 26.7p _and - 66 ° C.

Example 3

Pyrocatechin mono- (1-buten-3-yl) ether

Following the procedure of Example 1 was hydrolyzed with 222 parts by weight of O- (L-methoxyethoxy) phenyl- ^(R'-butyl, ten-3'-yl] ether. Yield: 152 parts by weight. Bp. 53,3p _a = 68 to 74 ° C.

Example '4

Pyrocatechin mono- (1-propyn-3-yl) -ether

Using the procedure of Example 1, 206 parts by weight of o- (1-methoxyethoxy) phenyl (1-propyn-3-yl) ether were hydrolyzed. Yield 140 parts by weight of the product, m.p. 49-50 ° C.

Example 5

Pyrocatechin mono- (2-butin-4-yl) ether

Following the procedure of Example 1, it was hydrolyzed

110 parts by weight of o- (1-methoxyethoxy) phenyl (2 ' -butin-4 &apos; -yl) ether, yield 77 parts by weight of product 1.144 to 47 [deg.] C.

The compounds prepared according to this process are important intermediates for the preparation of plant protection active substances, as well as pharmaceuticals and pharmaceuticals. of veterinary products.

The known preparation of known plant protection agents takes place, for example, by reacting pyrocatechinether with methyl isocyanate. For example, reaction of o-isopropoxyphenol with methyl isocyanate affords o-isopropoxyphenyl N-methylcarbamic acid ester, which is a known insecticide.

The pyrocatechin bis ether required as starting material is prepared by reacting pyrocatechin with a vinyl ether of formula R ⁴ OR ³ , wherein R 4 is optionally lower alkyl substituted vinyl and R 3 is lower alkyl, cycloalkyl, β-chloroethyl, alkoxyalkyl, lower alkenyl or acyl or is reacted with an α-haloether of the formula

R1 *

I hal - C — OR 3,

R ² .

wherein hal is chlorine, bromine or iodine and R ¹ is hydrogen or lower alkyl, R2 is unsubstituted or halogen, methoxy "or ethoxy-substituted lower alkyl or benzyl and R3 is lower alkyl, cycloalkyl, / З-chloroethyl, alkoxyalkyl, lower alkenyl, lower alkynyl or acyl, in the presence of a base and optionally a bisected ether of formula

R ¹ С-ОЯ

wherein R 1, R 2 and R 3 are as defined above, reacted with pyrocatechin and the reaction product of formula

wherein R 1, R 2 and R 3 are as defined above, reacted with an alkylating agent RX such as alkyl sulfates, arylsulfonic acid alkyl esters or branched or unbranched alkyl, alkenyl and alkynyl halides which may be substituted by a halogen atom (chlorobromine or iodide), or an arylalkyl halide (benzyl) in an alkaline medium according to the following equation

The radicals R @ 1, R @ ² and R @ ³ are as defined above, R is branched or unbranched alkyl having 1 to 4 carbon atoms, alkenyl or alkynyl which may be substituted by a halogen atom (chlorine, bromine, iodine) or arylalkyl (benzyl); X is halogen (chloro, bromo or iodo), alkoxy, sulfonyl or arylsulfonyl.

Alkylation conditions with respect to temperature, pressure, solvents and base corresponding to those commonly used in the synthesis of ethers (see also Houben-Weyl, Methoden der organischen Chemie, vol. 6/3, p. 83). To carry out the following reaction, for example

^CH 3

н.о + а-сч '

C = CH Max Maxi ~ ³ ЧР

The sodium salt is heated in the form of a hydrate or in anhydrous form, for example in acetonitrile or dimethylformamide with a slight excess of 1-butin-3-yl chloride to boiling until the solution reacts neutrally. Etherification takes place in good yield.

Other analogous pyrocatequin derivatives are e.g.

(t = OC-OR ^1a

Ri R2 R3 R boiling point ° C H H CH3 1 — C3H7 CHs OF 13.3Pa = 82 to 85 H H CH3 —CH \ C = CH CH3 13.3Pa = 100 to · 103 H H C2H5 OF —CH \ C-CH 13.3Pa = 104 to 106 H CHs CH3 1 — C3H7 CH3 '/ 26.7Pa = 60 to 66 H CH3 CH3 / —CH \ C = CH 26.7Pa = 100 · to 110

R1. R2 R ³ R boiling point ° C H CH3 C2H5 CH3 / —CH \ C = CH 26.7Pa = 100 to 111 H H CH3 CÉ3 CHs CHs • —CH2 —CH = CH2 —CH2 — C = CH 40Pa = 100 to 102 H CH3 CH3 CH2 OF —CH2 — c \ CH3 40Pa = 85 to 91 H CH3 CH3 —CH2 — CH = CH — CH3 H CH3 CH3 - ^c4 OJ 26.7Pa = 130 to 150

The following examples illustrate the preparation of ethers.

Example 1 a d 6 a

O- (1-Methoxyethoxy) -phenol-3H2O salt

To 168 parts by weight of o- (1-methoxyethoxy) -phenol in an Erlenmeyer flask was added 200 parts by weight of a 20% by weight aqueous sodium hydroxide solution under nitrogen. After shaking briefly, the reaction mixture was allowed to stand for one hour at room temperature. The crystalline slurry was filtered off and washed with a 1: 1 mixture of ether and isopropanol. The product obtained was almost colorless. Yield 80-90% of theory, m.p. 72-73 ° C. Crystalline water is easily removed in a water pump vacuum at 70-110 ° C.

For C9Hi7NaOe '(244) calculated:

44.3 C, 7.0% H, 9.4% Na;

found:

% C, 43.8;% H, 7.0%;

Example 6 b o- (1-methoxyethoxy) -phenyl-r-butin-3´-yl) -ether

244 parts by weight of o- (1-methoxyethoxy) -phenol sodium trihydrate or 190 g of the anhydrous salt are suspended in 300 parts by weight of dimethylformamide. 100 parts by weight of 1-butin-3-yl chloride are added dropwise with stirring and heating to boiling. After about one hour, a stoichiometric amount of sodium chloril precipitated. The mixture is allowed to cool, the sodium chloride is filtered off, the solution is concentrated, 10.00 parts of benzene are added and washed well with 2 X 500 ml of 2 N aqueous NaOH solution. After. After drying over sodium sulfate, the solvent was evaporated and the product. is distilled after adding a small amount (tip of spatula) of succinic acid.

Yield: 182 parts by weight of product, b.p. 20.7Pa = 100-110 ° C.

For C 13 H 16 O 3 (220) calculated:

70.9 o / _o c, 7.3% H;

found:

70.5% C, 7.5% H.

Example 7 o- (1-methoxyethoxy) -phenyl-1-isopropyl ether

The procedure podlepříkladu 6 and instead of l-butyn-3-ylchlorldu using 150 wt. Parts of isopropyl tv 7P _and 26 = 60 to 66 degrees Celsius.

Example 8 o- (1-methoxyethoxy) -phenyl- (1'-buten-3'-yl) -ether

The procedure of Example 6 was followed and 110 parts by weight of 1-buten-3-yl chloride were used in place of 1-butn-3-yl chloride. M.p. 40Pa = 80-91 ° C.

Em C 13 H 18 O 3 (222) calculated:

70.3% C, 8.1% H;

found:

70.4% C, 8.3% H.

Example 9 o- (1-ethoxyethoxy) -phenyl- (1'-butin-3'-yl) -ether

440 parts by weight of pyrocatechin are dissolved in 1500 parts of tetrahydrofuran. After adding 1 ml of concentrated hydrochloric acid, 303 parts by weight of vinyl ether are added dropwise. Reaction mixture? The mixture is then kept at 65 ° C for one hour, allowed to cool and 720 parts by weight of a 30% by weight solution of technical sodium methylate in methanol are added. Then 400 parts by weight of 1-butin-3-yl chloride are added and the reaction mixture is heated to boiling until neutral. After the sodium chloride was filtered off, the filtrate was evaporated. The residual oil was dissolved in 3000 parts of benzene and washed five times with 1000 parts of 2 N aqueous sodium hydroxide solution and then dried over sodium sulfate. After evaporation of the solvent and addition of 2 parts by weight of succinic acid, the product distils at m.p.

For C 14 H 18 O 3 (234) calculated:

C, 71.8; H, 7.7;

found:

70.6% C, 8.0. % H.

Example 10-10- (1-methoxyethoxy) -phenylbenzyl ether

The procedure of Example 5 was followed and 133 parts by weight of benzyl chloride were used in place of t-1-butin-3-yl chloride. The reaction mixture is heated to boiling until neutral. Yield 175 parts by weight of product, m.p. = 26 ° C = 130-150 ° C.

For example, the etherification of pyrocatechin is carried out by reacting pyrocatechin with an amount necessary to etherify one hydroxyl. or up to about 50% excess or deficiency of the vinyl ether of the formula

R @ 1 - R @ 3 wherein R @ 3 is vinyl or lower alkyl having up to 3 carbon atoms substituted vinyl and R @ 3 is C1 -C4 alkyl, C3 -C7 cycloalkyl, .beta.-chloroethyl, alkoxyalkyl; methoxyethyl or ethoxyethyl, alkenyl of up to 4 carbon atoms, alkynyl of up to 4 carbon atoms, acyl such as acetyl, and the reaction is optionally carried out with the addition of catalytically active compounds such as acidic reactants such as mineral acids, acid salts, organic acids, α-haloethers, organic · or inorganic acid chlorides as well as ion exchangers · and Lewis acids, for example AlCl 3, FoCl 3, BF 3 · and the like, at a temperature of -5 ° C to 120 ° C, preferably at 40 ° C 50 ° C and / or with the addition of solvents or diluents indifferent to the reaction. partners (e.g., 5-8% by weight) such as ethers (diethyl ether, tetrahydrofuran, dioxane) hydrocarbons (e.g., n-hexane, benzene, toluene, xylene) and halogenated hydrocarbons (CH 2 Cl 2, CHCl 3 CCl 4). .

The reaction of pyrocatechin with vinyl methyl ether can be represented by the following equation:

The catalysts mentioned above can advantageously be used.

Further, pyrocatechinethers can be prepared by reacting preferably equimolar amounts or up to 50% excess or deficiency of the α-haloether of the formula

R1 hal — C — OR3,

R2 wherein hal is chlorine, bromine or iodine and R1 is hydrogen or lower alkyl of 1 to carbon atoms, R2 is unsubstituted or halogen (chlorine, bromine or iodine), methoxy or ethoxy substituted lower alkyl of 1 to 3 carbon atoms or benzyl, R 3 is C 1 -C 4 alkyl, C 3 -C 7 cycloalkyl, 1-chloroethyl, alkoxyalkyl such as methoxyethyl, ethoxyethyl, C 4 -C 4 alkenyl, C 4 -C 4 alkynyl, acyl such as acetyl, and R 1 and R 2 together with the carbon atoms to which they are attached and R 1 and R 3 together with the carbon or oxygen atom to which they are attached may form a five or six membered ring (cyclopentyl, cyclohexyl, tetrahydrofuryl and tetrahydropyranyl) ) with a pyrocatechin salt or with pyrocatechin in the presence of preferably an equimolar amount of an organic or inorganic base (e.g. alcoholate, alkali metal hydroxide or al1981 metal) 29 or an alkaline reacting substance, such as an alkali metal or alkaline earth metal carbonate. The reaction is represented by the following equation:

The radicals R ^1, R ² and R ³ are as defined above. Preferably, the reaction is carried out with dilute reactants, for example 5 to 80% by weight, of ether (diethyl ether, tetrahydrofuran or hydrocarbon n-hexane, benzene, toluene, xylene).

Vinylethers, respectively. The .alpha.-halogen ethers used for the reaction are known in the literature and are technically well prepared (see, e.g., W. Reppe and J. Ann. 601, 98 (1956)).

In the above processes, the excess of vinyl ether and / or vinyl ether is formed according to the excess. α-haloether equivalent amount of bisether II

(P) the reductions of R 1, R 2 and R 3 are as defined above.

In quantitative yield, the above-mentioned bisethers can be advantageously prepared by reacting pyrocatechin with at least twice the molar amount of vinyl ether.

Catalysts and reaction conditions in terms of temperature and solvent are analogous to those described for the preparation of compounds of Formula I.

A further process for the preparation of the compounds of formula I is to react the bisether of formula II with pyrocatechin according to the following equation:

residues R1, R2, R3 and catalysts and reaction conditions are the same as in the preparation of compounds of formula I from vinyl ethers.

The pyrocatechin derivatives of the formulas I and II are deposited in the form of colorless oils which, after stabilization with organic or inorganic bases, can be distilled under vacuum without decomposition. The following table gives an overview of the prepared compounds:

formula I:

R ¹ R ² R ³ tv ° С; n _D 25 H н СНз mp: 53.3 Pa: 89-93 H Н С2Н5 mp 13.3 Pa 90-100 H СНз СНз rt: 66.7 Pa: 85 to 90 H СНз С2Н5 m.p. 133.3 Pa: 78-81 H СНз П-СЗН7 m.p. 133.3 Pa: 96-98 H СНз I-C3H7 mp: 133.3 Pa: 89-94 H СНз I-C4H9 mp: 26.7 Pa: 94-98 H СНз 0 mp: 26.7 Pa: 128-135 H СНз О m.p. 533.3 Pa: 132-136 H СНз С О СНз n _D ²⁵ : 1.5075 H СНз СОС2Н5 n _D 25: 1.4905 H СНз —СНг — СН = СНг H СНз —СНг — С = СН СНз of H СНз —Сн \ Се = СН H СНз —CH2 — СН2 — ОСНз H СНз —СН2-СН2 — ОС2Н5 H CH2Cl —СНз n _D 25: 1.5135 H CH2Cl -С2Н5 n _D 25; 1,5146 H CH2Cl —СН2 — СН2С1 no ²⁵ : 1.4975. H CH2Cl СОСНз n _D 25: 1.5012 H СНгВг СНз n _D 25: 1.5 3 40 H CH2I СНз H С2Н5 СНз 200.0 Pa: 105-113 H С2Н5 С2Н5 m.p. 66.7 Pa: 100-103 H С2Н5 СН2 — с = сн H СН2— СН2С1 СНз n _D 25; 1,5023 H СН2 — CHCI — СНз СНз H СН2 — СНВг — СНз СНз H СН2— I want — С2Н5 СНз H П-СЗН7 СНз H 1-C3H7 СНз H СН = СНг СНз H с = сн СНз H СН2 — с = сн СНз H ^сн я.-О СНз СНз СНз СНз СНз СНз С2Н5 СНз CH2Cl СНз n _D 25: 1.5024 СНз CH2Cl С2Н5 СНз СНгВг СНз СНз СНгВг С2Н5

tv ° C; n _D 25

R ¹

R2 R3

CH3 C2H5 CH3 CHs 11-C3H7 СНз CH3 1-C3H7 СНз C2H5 C2H5 CH3 0 CH3 Q CHs

Formula II:

СНз

CH3 C2H5

I-C4H9

mp 66.7 Pa: 115-118

H H H

H

H

СНз

СНз

СНз

53.3 Pa: 105 - 109

m.p. 66.7 Pa: 99-105

v. 40.0 ’Pa: 97 to 102

m.p. 40.0 Pa: 124-128

Example 11a o- (1-methoxyethoxy) -phenol

110 parts by weight of pyrocatechin are suspended in 100 parts by weight of toluene. At 5 ° C, 64 pbw of -40 ° C cooled vinyl methyl ether are added in one portion, followed by a drop of concentrated hydrochloric acid. While stirring, the reaction mixture is heated to about +20 ^o C, the reaction initiated and the internal temperature rises to about 65 ° C, optionally using ice-water cooling. The reaction mixture is kept at 65 ° C for half an hour, followed by the addition of 5 parts by weight of 2 N sodium hydroxide solution. After cooling, drying over sodium sulfate, the solvent is removed in a rotary evaporator and the residue is distilled in vacuo. 155 parts by weight of product are obtained at 66.7 Pa = 85-90 ° C.

For C 9 H 12 O 3 (168) calculated: 64.1% C, 7.2% H; ........

Found: C 64.4%, H 7.0%.

Example 11b

Pyrocatechin-bis - [(1-methoxy) -ethyl ether]

The procedure described in Example 11a was carried out but twice (128 pbw) of vinyl methyl ether was used. 122 parts by weight of a colorless oil are obtained, b.p. = 99-150 ° C.

For C 12 H 18 O 4 (226) calculated: 63.7% C, 8.0% H;

found: 63.3% C, 8.1% H.

Example 11c o- (1-methoxyethoxy) -phenol

113 parts by weight of pyrocatechin-bis- [(1-methoxy) ethyl ether] and 55 parts by weight of pyrlcatechin are mixed at 40 ° C with 0.5 parts of SOCl 2 and the reaction mixture is stirred for half an hour at this temperature. The mixture was allowed to cool and 2 ml of a 25% (w / w) aqueous NaOH solution was added, the mixture was separated, dried over sodium sulfate and the solvent was evaporated. 168 parts of the aforementioned compound, b.p. = 85 to 99 degrees Celsius, are obtained.

Example 12a o- (1-ethoxyethoxy) -phenol

220 parts by weight of pyrocatechin are suspended in 200 parts by weight of toluene. After adding 2 drops of concentrated hydrochloric acid, 150 parts by weight of ethyl vinyl ether are added under stirring. External cooling by ice keeps the internal temperature so that it does not exceed 65 ° C. At the end of the reaction time, all pyrocatechin is dissolved. Then 5 parts by weight of 2 N NaOH solution are added to the reaction mixture, allowed to cool, dried over sodium sulfate and the product is distilled under vacuum after evaporation of the solvent. Yield almost quantitative t 133.3 Pa = 78-81 ° C, n _D ²⁵ = 1.5032.

Calcd: C 66.0%, H 7.7%;

found: 66.3% C, 7.9% H.

Example 12b

Pyrocatechin-bis - [(1-ethoxy) -ethyl ether]

If 300 parts by weight of ethyl vinyl ether are used instead of 150 parts by weight, 248 parts by weight of a colorless oil are obtained, b.p. = 97-102 ° C.

For C14H22Q4 (154) _; ...

calculated: 66.2% C, 8.6% H;

found: 66.4% C, 8.7% H.

Example 12c o- (1-ethoxyethoxy) -phenol

127 pbw of pyrocatechin-bis- [(1-ethoxy) ethyl ether] and 55 pbw of pyrocatechin were reacted as described in Example 11c. Yield: 179 parts of phenolic compound, m.p. 133.3 Pa = 79-80 ° C.

Example 13 o- (methoxymethoxy) -phenol

110 parts by weight of pyrocatechin are dissolved in 400 parts by weight of benzene. At room temperature, 101 parts by weight of triethylamine and 81 parts by weight of chloromethyl methyl ether are added dropwise simultaneously so that the reaction medium is slightly basic. The reaction mixture is then heated at reflux for one hour, allowed to cool, the hydrochloride is filtered off, washed with water and dried over sodium sulphate, evaporated and distilled in vacuo. Yield: 120 parts by weight, tv 53.3 Pa 89 ° C, n _D ²⁵ = 1.5150.

For СвНюОз (154) calculated: 62.3% C, 6.5% H;

found: 62.0% C, 6.5% H.

The pyrocatechin monoether can also be prepared via the product of formula II

C ^0R R * č ^ qcoR * (ID where

R ¹ , R ² , R ³ and R are as defined above, and the reaction can also be carried out from pyrocatechin in one step in quantitative yield.

Claims (1)

Process for preparing pyrocatechin ethers of formula I or benzyl, characterized in that a pyrocatechin derivative of formula II STEED R ¹ OC-OR ³ AND R * (ii) wherein R is alkyl, alkenyl, or alkynyl having up to 4 carbon atoms and which are optionally substituted with a halogen atom, R is as defined above, R ¹ is hydrogen or C 1 -C 4 alkyl, R ² is hydrogen or optionally halogen, methoxy or ethoxy-substituted alkyl having 1-3 carbon atoms or benzyl, R ³ is C 1 -C 4 alkyl, C 3 -C 7 cycloalkyl, β-chloroethyl, methoxyethyl, alkenyl or alkynyl having at least 4 carbon atoms, acetyl or propionyl; and R ² and R ³ optionally form together with the carbon and oxygen atom to which they are attached a five or six membered ring to cleave in an acidic environment at a temperature of 40 to 100 ° C.