DE2228333A1 - 2-butyn-4-ol and derivs prodn - by reacting aldehydes or ketones with allene - Google Patents

Abstract

Cpds. have the general formula: (in which R' and R2 denote H, (un)satd. straight or branched, aliphatic 1-20C hydrocarbon radicals, cycloaliphatic hydrocarbons contg. 5-6C atoms in the ring, or a phenyl: R' and R2 may also form together a 4-6C alkylene bridge) are produced by reacting an aldehyde or ketone having the formula O=C(R')R2 with allene or an alline-contg. gas mixt. esp. with propyne, in a water-immiscible solvent (having a dielectric constant 10) at 0-50 degrees C in the presence of an alkaline condensation agent. These cpds. can be used as sleeping and sedative drugs, aroma agents and inters, for org. syntheses.

Description

Process for the preparation of optionally substituted 2-butyn-4-ols The invention relates to a process for the production of optionally substituted 2-butyn-4-ols by reacting an aldehyde or a ketone in the presence of alkaline condensation agents in a water-immiscible solvent with all or with a gas mixture containing all.

The production of 2-butyn-4-ols by reacting aldehydes and Ketones with propyne in the presence of alkaline condensing agents is known.

It is also known from the German Offenlegungsschrift 1 955 843 that that one can mutually transform propyne and all by using propyne and contacting all-containing gas with a catalyst solution composed of a dipolar aprotic solvent with a dielectric constant above of 10 and a hydroxide or alkoxide of an alkali metal having an atomic number higher than 10.

It has been found that 2-butyn-4-ols of the formula I. in which R1 and R2 represent hydrogen, a saturated or unsaturated, branched or unbranched aliphatic hydrocarbon radical with 1 to 20, preferably 2 to 13 carbon atoms, a cycloaliphatic hydrocarbon radical with 5 or 6 carbon atoms in the ring or a phenyl radical, or R1 and R2 together mean an alkylene radical having 4 to 6 carbon atoms, can be produced in a very advantageous manner if an aldehyde or a ketone of the formula II in which R1 and R2 have the meaning given qben, in the presence of an alkali hydroxide, alkali alcoholate, alkali amide or metallic lithium as an alkaline condensation agent in a virtually water-immiscible solvent with a dielectric constant of less than 10 at temperatures from 0 to 500C with all or a Reacts all containing gas mixture.

It was surprising that Allen under the reaction conditions mentioned can be converted to 2-butyn-4-ols, since it is known on the one hand that for the mutual conversion of Propin and Allen according to the German Offenlegungsschrift 1 955 843 the presence of certain aprotic solvents is required and there on the other hand in the German Offenlegungsschrift 1 668 399 will that all of itself when treated with a dispersion of sodium or of sodium containing lithium is relatively inert, while propyne in the corresponding Propynyl alkali metal compound is transferred. Furthermore, in the latter Offenlegungsschrift stated that pure metallic lithium under the reaction conditions not responding even with propyne.

Pure allene can be used for the conversion to 2-butyn-4-ols. However, it is used with particular advantage in the thermal cleavage of saturated hydrocarbons resulting mixture of allene and propyne, the only could be separated into allene and propyne by very laborious distillation processes. A complex purification of the Allen-Propenemisches is not necessary, since without Disadvantages also those gas mixtures can be used according to the invention, which contain other hydrocarbons, olefins or diolefins in addition to all and propyne.

Compounds of the formula II are used as aldehydes or ketones in which R1 and R2 each represent hydrogen, a saturated or unsaturated, branched or unbranched aliphatic hydrocarbon radical with 1 to 20 carbon atoms, a cycloaliphatic hydrocarbon radical with 5 or 6 carbon atoms in the ring or a phenyl radical, or R1 and R2 together represent one Alkylene radical with 4 to 6 carbon atoms, into consideration. Of particular interest are aldehydes or ketones in which R1 is hydrogen or a saturated hydrocarbon radical having 1 to 4 carbon atoms and R2 has the meaning given above for R1 and R2. Examples include: acetaldehyde, propionaldehyde, isobutyraldehyde, citronellal, acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-methylhepten-1-one-6, 2-methylhepten-2-one-6, geranyl acetone or hexahydrofarnesylacetone.

The basic condensing agents are in particular the hydroxides, Alcoholates and amides of sodium and potassium are possible.

Metallic lithium can also be used. Particularly advantageous the inventive method with sodium or potassium alcoholates of carry out primary or secondary alcohols with 4 to 8 carbon atoms, as these alcoholates particularly economical from aqueous alkaline solutions by azeotropic distillation can be obtained with the only limited water-soluble alcohols. The alkaline ones Condensing agents are generally used in amounts of about 0.2 to 1.5 moles, preferably 0.3 to 1.0 moles per mole of aldehyde or ketone are used.

When using condensation agents containing potassium and tetrahydrofuran as a solvent, even the use of catalytic amounts is sufficient, d. H. amounts from about 0.2 to 0.5 moles of condensing agent per mole of aldehyde or ketone.

As a practically immiscible solvent with a dielectric constant less than 10 are aliphatic or aromatic hydrocarbons, such as Toluene, xylene, dialkyl ethers such as diethyl ether, cyclic ethers such as tetrahydrofuran, Hexamethylene oxide and dioxane and the acetals of lower aliphatic aldehydes, such as the diacetals of formaldehyde or acetaldehyde with aliphatic alcohols with 1 up to 4 carbon atoms. Also mixtures of the solvents mentioned can be used. The following solvents may be mentioned in particular: tetrahydrofuran and cyclic ethers of the tetrahydrofuran type and formaldehyde dibutyl acetal, Formaldehyde diisobutyl acetal; Acetaldehyde diethyl acetal, acetaldehyde dibutyl acetal, Acetaldehyde diisobutyl acetal, dioxane. The organic solvents are used generally in amounts of about 3 to 15> preferably 5 to 10 parts by volume per part by volume of aldehyde or ketone.

The organic solvents must not contain any free hydroxyl groups or contain amino groups, as this reduces the effectiveness of the basic condensing agent is reduced.

On the other hand, when using extremely poorly soluble or Difficult to suspend condensing agents - such as the alkali hydroxides - It is advantageous to use small amounts of a compound containing hydroxyl groups as a solubilizer to add to the reaction mixture. One or more solubilizers are used as solubilizers polyhydric alcohols with 1 to 5 carbon atoms, such as methanol, {ethanol, isobutanol, ethylene glycol or glycerine into consideration. The solubilizers are generally used in Amounts from 0.5 to 5 parts by volume per 100 parts by volume of the solvent.

To carry out the process is generally first a Suspension of the alkaline condensing agent in the chosen solvent or Solvent mixture saturated with all or the gas mixture containing all and then at temperatures from 0 to 5000, preferably from 10 to 30 ° C., the aldehyde or the ketone is introduced slowly while the gas or gas mixture is passed through. The exhaust gases leaving the reaction mixture are collected and, if necessary fed back into the process.

When the aldehyde or ketone has been introduced, the reaction mixture becomes mixed with water and the phases that form are separated from one another. The organic Phase is neutralized and then distilled. Used to neutralize any inorganic or organic acids that contain the Reaction product do not change chemically. Examples include: formic acid, acetic acid, Adipic acid and sulfuric acid.

During the distillation of this organic phase, those in the solvent still dissolved amounts of unreacted allene or gas mixtures containing allene regained.

From the aqueous alkaline phase can by reacting with primary or secondary alcohols with 4 to 8 carbon atoms and then azeotropic distillation the alkali alcoholates which can be used as alkaline condensation agents, this only limited.

water-soluble alcohols are obtained.

The reaction of the aldehyde or ketone with all or the all containing Gas mixture can also be carried out under increased pressure. This way of working is advantageous if the solvent has only a low solubility for the Allen or the gas mixture containing allene, which z. B. with xylene or toluene the case is. In most cases, however, working under increased pressure unnecessary.

With the help of the method according to the invention it is possible to use the butynols of the formula I in a simple and economical manner from the as a by-product the production of allene obtained from butadiene or gas mixtures containing allene and to produce carbonyl compounds.

The conversion of all to propyne and the reaction of propyne with it the carbonyl compound takes place in the same reaction medium.

The work-up of the reaction mixture after the reaction has taken place is extremely simple, since the solvent used with the reaction mixture added water are not miscible. Through this simple processing option wastewater and thus environmental problems are avoided. Furthermore, you can the solvents used according to the invention easily and completely different from those formed Separate acetylene alcohols, whereby very pure acetylene alcohols are obtained, what with solvents such as dimethyl sulfoxide and N-methylpyrrolidone, for example is not the case.

The butynols of the formula I produced have as intermediates for organic syntheses, as sleeping aids and sedatives as well as fragrances Found interest. In particular that from 2-methylhepten-2-one-6 or 2-methylhepten-l-one-6 2,6-dimethyl-2-nonen-7-yn-6-ol produced with all or all-containing gases and 2,6-dimethyl-l-nonen-7-yn-6-ol show good odorant properties.

The parts mentioned in the following examples are parts by weight.

Example 1 The suspension of 112 parts of potassium isobutylate in 67 parts Xylene is distributed in 1600 parts of tetrahydrofuran with stirring and the resulting Suspension saturated with pure allene for one hour at temperatures of about 250C. About 150 parts of allene are dissolved in the process.

Over the course of 4 hours, all entered 252 parts of 2-methyl-lhepten-6-one at temperatures from 25 to 30 ° C. In A freezer system collects 24 parts of exhaust gas. The exhaust gas has the following composition: 84% propyne and 16% allene.

After the ketone has been introduced, 100 parts of water are added to the reaction mixture given. 120 parts of an aqueous 43% strength potassium hydroxide solution are formed, which are used again for Manufacture of potassium isobutylate can be used.

The organic phase formed is obtained by adding 2 parts of formic acid neutralized and then distilled. During this distillation, the im Solvent dissolved, unreacted allen propyne mixture collected. You get 276 parts of 2,6-dimethyl-l-nonen-7-yn-6-ol with a boiling point of Bp8 = 99 ° C and 31 Parts unreacted 2-methyl-1-hepten-6-one. The yield is 94.5 ffi of theory, based on converted 2-methyl-1-hepten-6-one.

Example 2 In the suspension of 112 parts of potassium isobutylate in 67 Parts of xylene and 1600 parts of tetrahydrofuran are introduced at 200C, a gas mixture, which besides other hydrocarbons, olefins and butadiene 44% allene and 22 ffi contains propyne. After saturating the suspension with the gas mixture for 1 hour one begins with further introduction of the gas mixture 252 parts of 2-methyl-2-hepten-6-one to be entered. The registration will be finished in 3 hours. The reaction temperature becomes held at 20C during initiation.

The reaction mixture is then mixed with 100 parts of water, the aqueous potassium hydroxide solution formed is separated off and the organic phase is added by adding 1 part sulfuric acid neutralized and then distilled. You get 268 Parts of 2,6-dimethyl-2-nonen-7-yn-6-ol with a boiling point Ko 5 = 65 to 660C and 22 parts of unreacted 2-methyl-2-hepten-6-one The yield was 88.5% of theory, based on 2-methyl-2-hepten-6-one.

Example 3 In the mixture of 7 parts of lithium chips and 500 Parts of tetrahydrofuran are introduced into pure allene with stirring. The temperature the mixture initially rises to about 45 ° C., but then falls off again. Under Simultaneous introduction of further allene into the mixture at 20 to 30 ° C entered in the course of 4-8 hours 126 parts of 2-methyl-2-hepten-6-one.

A total of 120 parts of all are initiated. The reaction mixture 20 parts of water are added. The separated organic phase is neutralized and distilled. The distillation gives 138 parts of 2,6-dimethyl-2-nonene-7-yn-6-ol with a boiling point Kp8 = 97 ° C and a refractive index nD 25 = 1.4685 and practically ' no unreacted 2-methyl-2-hepten-6-one.

The yield of 2,6-dimethyl-2-noen-7-yn-6-ol is 83% of theory.

The recovered in the distillation in a freezer container 80 parts of the gas mixture consist of 60% all, 7% propyne and 33% Propylene.

Claims (5)

Claims Process for the preparation of 2-butyn-4-ols of the formula I. in which R1 and R2 represent hydrogen, a saturated or unsaturated, branched or unbranched aliphatic hydrocarbon radical with 1 to 2G carbon atoms, a cycloaliphatic hydrocarbon radical with 5 or 6 carbon atoms in the ring or a phenyl radical, or R1 and R2 together represent an alkylene radical with 4 to. 6 carbon atoms mean, characterized in that an aldehyde or a ketone of the formula II in which R1 and R2 have the meaning given above, in the presence of an alkali hydroxide, alkali alcoholate, alkali amide or metallic lithium as an alkali condensation agent in a virtually water-immiscible solvent with a dielectric constant of less than 10 at temperatures of 0 to 50 ° C Reacts all or a gas mixture containing all. 2. The method according to claim 1, characterized in that one Aldehyde or a ketone of the formula XP, in which R1 is hydrogen or a saturated one Hydrocarbon with 1 to 4 carbon atoms and R2 in claim 1 for R1 and R2 has the meaning mentioned, reacts with all or with a gas mixture containing all. 3. The method according to claim 1, characterized in that one is tetrahydrofuran or a cyclic ether of the tetrahydrofuran type is used as the solvent. 4. The method according to claim 1, characterized in that eiti Potassium alcoholate from an alcohol with 4 to 8 carbon atoms as alkali alcoholate used. 5. The method according to claim 1, characterized in that the with water practically immiscible solvent small amounts of one or polyhydric alcohols with 1 to 5 carbon atoms added.