DE1593912A1 - Dibenzofuran derivatives and process for their preparation - Google Patents

Description

Dibenzofurn derivatives and processes for their preparation (excretion from patent application P 15 70 772.9) The present invention relates to alkenyl-substituted Dibenzofurans and their method of manufacture.

Dibenzofuran is a well-known oxasol, also called diphenylene oxide is known. It starts a crystalline festival dance with a sharp point of stwa 87 ° C and a boiling point of about 288 ° C. Bs is insoluble in water and in alcohol, Ether and eenzene are slightly soluble. Technically, they are carbonized during manufacture chemical compounds that require a heterocyclic ring structure are used, Benzofuran itself is sush and can be made from coumarin will that. (@@@@@ alich dibenzofuran comes from coal tar and oicht from the synthesis from benzofuren.

The heterocyclic structure of dibenzoturan makes it a reality suitable with various connections. As a result, it can be used during manufacture of various chemicals, such as insecticides, dyes, pharmaceuticals Agents, lubricants and lubricants, etc., can be used.

There is a need for new dibenzofuran derivatives that increased Have chemical reactivity, allowing the synthesis of new chemicals and others Products with various desirable chemical and physical properties would be possible. It would also be desirable to have new retive materials available u set that to the polymerization with the formation of new polymeric products with controlled physical and chemical properties would be enabled.

The object of the present invention is to create dibenzofuran derivatives and process for their production The objectives according to the invention are organized by organisoche Compounds in the form of alkenyl-substituted dibenzofurans of selected types and Creation of methods for producing the same achieved.

The present invention relates to 4-alkenyl-substituted dibenzofurans of the general formula in which n is from 0 to 21 and R, R 'and R "are each a hydrogen atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent, and processes for preparing the same.

The 4-alkynyl-substituted dibenzofurans according to the invention can be produced according to the invention in an effective and controllable manner, the desired chemical and physical properties achieved in the products will.

They are used for a number of purposes including manufacture of new chemicals, pharmaceutical products, fungicides, insecticides, dyes and other chemical compounds, and in particular for the production of polymers suitable, which in turn are useful for various purposes, for example as electrical insulation, synthetic fibers and materials used in manufacturing of slides, adhesives. Coatings and coatings and the like. Usable are, and the fernev with selected sensitizers with the formation of new products, such as o @ ganischen photoconductors and the like. To be able to react.

A special group of 4-alkenyl substituted dibenzofvrans according to the invention are the compounds of the formula in which n has the meaning given above.

The above and other objects, features, and advantages of the present Invention are from the following more detailed description of preferred embodiments of the invention can be seen.

According to the invention, the new 4-elkenyl-substituted dibenzofurans can be prepared from 4-alkali-substituted dibenzofurans by reacting the dibenzofuran, which is substituted in the 4-position by an alkali metal, with a compound providing a suitable alkenyl substituent, so that the component of the alkali metal which results in an alkenyl substituent on the alkali metal the 4 position, is substituted. Depending on the carbon chain length of the desired alkenyl substituent, the substituent can be introduced as a more recently or formed in situ on the dibenzofurad either from an alcohol or a monohalogenated alkene. The end result is a 4-alkenyl substitute. uated dibenzofuran of the general formula Wherein each of the radicals R, R ″ and R ″ denotes a water atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent and n denotes a value from 0 to 21.

It is already known that 2-vinyldibenzofuran is produced by converting dibenzofuran with acetyl chloride or acetic anhydride in a Friedel-Crafts reaction, subsequent catalytic reduction of the obtained 2-acetyldibenzofuran under high pressure and subsequent dehydration of the 2-dibenzofurylmethylearbinois thus formed. In the Friedel-Crafts reaction, however, 4-acetyldibenzofuran is only formed in very small amounts, so that this Arbeitsswsise for the production of 4-vinyldibenzofuran is practically not signed.

However, it has now been found that 4-vinyldibenzofuran can be obtained with good yields in high units by adding an alkali dibenzofuran of the formula where X is a sodium, potassium or lithium atom, reacted with acetaldehyde under anhydrous, non-oxidizing conditions, the product obtained is hydrolyzed and then the secondary alcohol of the formula that is formed is dehydrated to form 4-vinyldibenzofuran.

It has been found forner that the compounds of the general formula I, for which n is 1 or a value from 3 to 21, can also be prepared from an alkali dibenzofuran of the formula II given above by using this under anhydrous, non-oxidizing conditions a monohalogenous Alkon from Fors @@ where n represents the value 1 or a value from 3 to 21 and the other symbols have the meanings given above, to an alkenyl-substituted dibenzofuran of the formula what are the three different symools given above. Have meanings, is implemented. However, this process is not suitable for the preparation of the compounds of the general formula I for which n has the value 2, ie for 4-eutenyldibenzofursne, de butadiene-type products are formed in this process. It was found, however, that the 4-butenyldibenzofurans can also be prepared from an alkali diberzofuran of the formula II given above, in which this under anhydrous conditions under anhydrous conditions with a 1,4-dihalogenated Suten der general formula in which R, R ', R ", R" 3 and R "" each represent a hydrogen atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent and the radicals A, which are identical or different from one another, can be chlorine- , Bromine or iodine atoms mean, reacted and then under anhydrous; non-oxidizing conditions from the monohalogenated butyldibenzofuran formed of the form? wherein the various symbols have the meanings given above, in the presence of a hydrogen halide splitting catalyst, hydrogen halide to form a compound of split off or the monohalogenated butyldibenzofuran formed is converted into an amine, this is oxidized and the amine oxide formed is pyrolyzed.

According to the invention it is thus possible to prepare all compounds of the general formula I given above by a process in which a 4-alkali-substituted dibenzofuran of the general formula II given above is used as the starting substance and this under anhydrous, non-oxidizing conditions with an alkenyl substituent of the formula where n is a value from 0 to 21 and R, R 'and R "are each in a hydrogen atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent, or a substituent which can be converted into such a substituent is exchanged with the alkali atom is reacted and, optionally after converting the introduced substituent into an alkenyl substituent of the above formula, the 4-alkenyl-substituted dibenzofuran formed is obtained.

The 4-alkali-substituted dibenzofurans used as starting substances of the formula II can be prepared by known methods. You can do it Implementation of dibenzofuran with various reactive alkali compounds, for example n-butyllithium, sodium hydride, potassium hydride, lithium hydride, sodium ethyl and potassium ethyl, can be obtained. The desired reaction can be either anhydrous or non-oxidizing Conditions, for example under a nitrogen atmosphere, and at any suitable temperature, for example 0 to 55 ° C, or room temperature in the case of n-butyllithium, carried out while the two reactants dispersed in a suitable anhydrous reaction medium or solvent are. For example, dibenzofuran and n-butyllithium can be reacted at 35 ° C while they are sedated in anhydrous diethyl ether. The reaction proceeds normally virtually completely in the absence of a catalyst. Exploit up to about 80% or more can usually be used for the 4-position through an alkali metal substituted dibenzofuran can be achieved. As an example it should be mentioned that the Reaction of dibenzofuran and n-butyllithium in diethyl ether at room temperature in 3 hours to achieve a yield of 4-lithium dibenzofwran of 60% of the Theory can be ended, The following is the invention Hand of preferred embodiments explained in more detail.

In the preparation of 4-vinyldibenzofuran (formula I: n = O; R "- H), anhydrous acetaldehyde is added dropwise to a solution of the dibenzofuran substituted in the 4-position by an alkali metal in, for example, diethyl ether at low temperature4, for example 0 ° C, under anhydrous The reaction is allowed to proceed to completion at room temperature. During such a reaction, the 4-alkali dibenzofuran is preferably in a solvent for this, for example diethyl ether, dibutyl ether or another suitable, tetrahydrofuran and The acetaldehyde can also be present in a suitable medium such as diethyl ether or the like. The reaction generally takes place relatively quickly, for example within about 30 minutes, with a high yield of product, for example a yield of 60 % of theory. This the product, 4. (ß-hydroxyethyl) -dibenzofuran, contains the remainder of a secondary alcohol as a substituent in the 4-stollen on the phenylene ring instead of the alkali metal, and such a product corresponds to the formula This secondary alcohol can be used to form the desired @ -vinyldibenzofuran under suitable dehydration conditions, for example a temperature of 180 to 200 ° C, in the presence of a polymerization inhibitor such as hydroquinone, together with a dehydration catalyst in an effective concentration, for example 1% potassium hydrogen sulfate, based on the weight of the substituted dibenzofuran, water can be split off. The mixture is heated to the desired temperature under reduced pressure and reacted briefly, for example for about 30 minutes, after which the product is recovered and purified by distillation under reduced pressure. The @ -vinyldibenzofuran thus obtained has the formula In the preparation of the dibenzofuran derivatives of the general formula I, for which the alkenyl substituent has a carbon chain length of 3 or 5 to 23 carbon atoms, the dibenzofuran substituted in the 4-position by an alkali metal under non-oxidizing conditions, for example under a nitrogen atom, and in an anhydrous state with a monohalogenated alkene of the general form III, which has the same number of carbon atoms as the alkenyl substituent to be introduced into the dibenzofuran, with the introduction of this substituent in the dibenzofuran at the point of the alkali atom. The conditions are generally wa. Aser-free, non-oxidizing conditions, atmospheric pressure and a temperature in the range between approx. 0 and 140 ° C. The alkali dibenzofuran can be present in a suitable solvent, such as those listed above, the solvent being the same as the solvent for the monohalogenated alkene or compatible and miscible with it after the preparation of lithium dibenzofuran in an ether type solvent, this solvent can be replaced by xylene, ethylbenzene and the like.

The reaction is generally relatively rapid and is complete within about 6 hours, for example. The reaction product is a 4-position alkenyl-unsubstituted dibenzofuran of the general formula wherein R, R 'and R "each represent a hydrogen atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent and n represents the value 1 or a value from 3 to 2.

Such a product can be obtained by any suitable working method and cleaned, for example by first stripping off the solvent and then fractional distillation is carried out under reduced pressure. The product can also be recovered and purified by pouring it into ice water is separated, the organic layer is separated, the aqueous layer is extruded with ether will, the ether extracts with the organ @@@@ her Schicbe ve @@@ @@@ over wasseeiroiem Magnesium sulfate dried and evaporated to final dryness , the dried residue is dissolved in hexane and filtered, the filtrate is evaporated and the residue is recrystallized from methanol or the like. The yield of product is relatively high and is, for example, somewhat 60% of theory. A unique product is for use in the manufacture of the Polymers and for other purposes, such as the production of phar pharmaceutical agents and the like., Suitable.

For example, using this procedure, 4- (4-pentenyl) -dibenzofuran can be prepared by reacting lithium dibenzofuran with 5-bromo-1-pentene of the formula can be obtained. If 5-bromo-1-pentene is used, it becomes 4- (4-pentenyl) -dibenzofuran of the formula obtain. Lithium bromide occurs as a by-product in this reaction.

In the preparation of 4-butenyldibenzofurans, the 4-alkali-substituted dibenzofuran is reacted with a 1,4-dihalogenated butane of the general formula IV under anhydrous, non-oxidizing conditions. This reaction is carried out in a suitable reaction medium, for example a selected ether such as diethyl ether or tetrahydrofuran, which is a solvent for both the 1,4-dihalogenated butane and the 4-alkali-substituted dibenzofuran. The reaction is carried out at any suitable temperature, for example the reflux temperature for 2 hours. The reaction is carried out by adding the alkali-substituted dibenzofuran to the dihalogenated butane, so that a product is formed which contains a monohalogenated butyl-substituted dibenzofuran of the following formula, where A is a chlorine, bromine or iodine atom and R, R ', R ", R"' and R "" represent hydrogen atoms or alkyl, aryl, substituted alkyl or subatitulated aryl substituents. For example, dibenzofuran of the formula ## STR3 ## is substituted in the 4-position by a lithium atom in anhydrous diethyl ether or tetrahydrofuran at reflux temperature under a nitrogen atmosphere in a concentration of about 10%, based on the weight, of Lithitsdibenzofuran to 1,4-dichlorobutane in anhydrous diethyl ether added to the new compound, 4-Monoehlorbutylidbenzofuran of the formula to manufacture. Hydrogen halide can be split off from this product under anhydrous, non-oxidizing conditions using a relatively strong hydrogen halide removal agent, for example potassium tert-butoxide, and under suitable severe reaction conditions, for example at reflux temperature, in order to obtain the desired end product, the 4th -butenyl-substituted dibenzofuuan of the formula. to obtain. So the onochlorbutyldIbenzofuran using, for example, potassium tert. -butylate in a concentration of about 25%, based on the weight of the monochlorobutyldibenzofuran, can be dehydrohalogenated at reflux temperature to produce 4-butenyidibenzofuran. Other butenyl-substituted dibenzofurans of the general formula where R, R ', R ", R" 3 and R "" each represent a hydrogen atom or an alkyl, aryl, substituted aryl, or substituted alkyl group can be prepared in a corresponding manner.

The further particularly suitable procedure according to the invention for the production of the desired 4-butenyl-substituted dibenzofurans, a Amine formed from 4- (1-monohalobutyl) -dibenzofuran, this amine is oxidized and pyrolyzing the oxide to the desired product. For example, 4- (1-bromobutyl) -dibenzofuran reacted with dioxane and dimethylamine for about 12 hours and then with Benzene can be extracted. The product can then be poured over anhydrous magnesium sulfate dried, saturated with anhydrous hydrogen chloride and then separated and be dissolved in water.

The aqueous solution can be made basiseh with 10% sodium hydroxide solution and extracted with 3 parts of ether. The combined ether extracts can be dried over anhydrous magnesium sulfate. then the solvent can evaporated and the residue cooled to crystallize. You can get the product React in methael at room temperature with 30% hydrogen peroxide, then decompose the excess peroxide with 10% palladium carbon, filter and remove the solvent. The amine oxide can be heated under vacuum to make it to decompose to 4-butenyldibenzofuran, after which the product is dissolved in ether, successively washed with 10% hydrochloric acid, 5% sodium bicarbonate solution and water and can be dried over anhydrous magnesium sulfate.

The solvent can be evaporated and the residue can be used Crystallization must be cooled. The crystals can be recrystallized for further purification will.

This product can be used in a yield of up to about 80 s and more Theory can be obtained.

Thus, according to the process according to the invention, the 4-alkali-substituted Dibenzofuran can be reacted with a suitable reagent that ultimately produces the desired Alkenyl substituents on the dibenzofuran core. at the point (4-position) of the alkali atoms in the nucleus. »As already mentioned, the product can be an alkenyl substitute, which only contains hydrogen atoms on the carbon chain, or it may one or more hydrogen atoms on this substituent by alkyl or aryl or substituted alkyl or substituted aryl groups according to the above formula replaces leg.

Draw the 4-alkenyl-substituted dibenzofurans according to the invention are characterized by the fact that they have a terminal double bond that is highly is reactive and as a site for a polymerization or copolymerization under Formation of polymers or copolymers is able to act. Also can a substitution on the aromatic nucleus using various reactive components to the Manufacture of products such as agricultural Chemicals, pharmaceutical products and the like. That have the desired physical and have chemical properties, the following examples illustrate the invention without limiting it. In each example, the reactions are under anhydrous, non-oxidizing conditions, for example in anhydrous Solvents and under an inert gas atmosphere, such as under nitrogen, carried out unless otherwise stated.

Example 1 4-vinyldibenzofuran of the formula is prepared according to the following procedure: By reacting 220 g of dibenzofuran in 500 ml of diethyl ether as a solvent with 19 g of lithium and 122 g of butyl chloride in 100 ml of diethyl ether as a solvent at 35 ° C for 3 hours, 4-lithiumibenzofuran is produced in a solvent reacted with 1) 4 g of acetaldehyde, the addition reaction being carried out at OOC and atmospheric pressure for 30 minutes. The reaction product is hydrolyzed with dilute aqueous hydrochloric acid (10% by volume), and the substituted dibenzofurna of the formula is isolated. This compound is distilled at 1760C at 1 mm pressure and recrystallized from hexane. The purified product is obtained in this way with a melting point of 69 ° -69.5 ° C.

Analysis C14H12O2; Molecular weight: 212.25 Calculated: C 79.22 H 5.70 % Found: 79.32 5.60% The purified product is then heated to 200 ° C. during Water is split off for 30 minutes using 800 mg of a KHSO4 dehydration catalyst. The 4-vinyldibenzofuran formed is then removed from the reaction mixture by fractionation won.

The 4-vinyldibenzofuran has a boiling point of 122 ° C bel 0.45 mm Hg.

Analysis C14H100; Molecular Weight: 194.23 Calculated; C 86.57 H 5.19 % Found: 86.84 5.33% The purified product is found in about 60% yield % of theory received.

Example 2 4-Allydibenzofuran of the formula is manufactured according to the following procedure. 4-Lithium dibenzofuran is prepared by reacting 42 g of dibenzofuran in 250 ml of diethyl ether solvent with 3.5 g of lithium and 23 g of butyl chloride in 50 ml of diethyl ether solvent at 35 ° C. for 3 hours. The diethyl ether is then replaced by an equal amount of anhydrous xylene. The 4-lithium libenzofuren is then reacted in its solvent with 35 g of distilled allychloride at reflux temperature for 16 hours. The desired product is isolated by distillation. The product has a boiling point of 130 ° C at 0.05 Hg.

Example 3 4-Methyallydibenzofuran of the formula is prepared according to the following Arbeitsswesie, 4-lithium dibenzofouran is prepared by reacting 42 g of dibenzofuran in 250 ml of diethyl ether solvent with 3.5 g of lithium and 23 g of butyl chloride in 50 ml of diethyl ether at 35 ° C for 3 hours. The diethyl ether is then replaced with an equal amount of anhydrous xylene. The 4-lithium dibenzofuran is then reacted in its solvent with 60 g of freshly distilled methallybromide at reflux temperature for 16 hours. The desired product is isolated by distillation; Bp 0.05 = 135 ° C.

Example 4 4- (3-butenyl) dibenzofuran of the formula is manufactured according to the following procedure.

By reacting 42 g of dibenzofuran in 250 ml of tetrahydrofuran with 3.5 g of lithium and 23 g of eutyl chloride in 50 ml of tetrahydrofuran at 350 ° C. for 5 4-lithium dibenzofuran produced nu hours @ is converted to 540 g of 1,4-dibromobutane in 250 ml of tetrahydrofuran was added to give 60 g of 4- (4-bromobuty) dibenzofuran About 12 g of this product are poured into 120 ml of dioxane in a glass tube with 20 ml of dimethylamine included. The tube is heated at 1000C for 12 hours. Man extract the contents of the tube with benzene, wash with 10% aqueous sodium hydroxide solution and then with water until neutral and dries over. anhydrous magnesium sulfate. The solvent is evaporated.

4- (4-Dimethylaminobutyl) -dibenzofuran is obtained in this way. This connection is in an amount of 6.7 g in 55 ml of absolute methanol with 3.0 ml of 30% hydrogen peroxide oxidized to the amine oxide, which on decomposition at 75-150 ° C for 1/2 hour 4 g of 4- (3-butenyl) -dibenzofuran of boiling point 0.06 = 145 ° C. gives.

Example 5 4- (4-pentenyl) -dibenzofuran of the formula is manufactured according to the following procedure. 4-Lithium dibenzofurna is prepared by reacting 22 g of dibenzofuran in 200 ml of diethyl ether with 1.9 g of lithium and 16.5 g of butyl bromide in 50 ml of diethyl ether at 35 ° C. for 3 hours.

The diethyl ether is then anhydrous by an equal amount Replaced xylene. The 4-lithium dibenzofuran is then mixed with 22 in its solvent g freshly distilled 5-bromo-1-pentene at reflux temperature for 16 hours unset.

The 'desired educt is isolated by distillation; Kp0.04 = 137 ° C.

Analysis C17H16O; Molecular Weight: 236.32 Calculated; C 86.40 H 6.82% Found: 85.40 7.50% Beiapiel 6 4 * (5-hexenyl) -eibenzofuran of the formula is manufactured according to the following procedure. 4-Lithium dibenzofuran is prepared by reacting 22 g of dibenzofuran in 200 ml of diethyl ether with 1.9 g of lithium and 16.5 g of butyl bromide in 50 ml of diethyl ether at 35 ° C. for 3 hours.

The diethyl ether is then replaced by an equal amount of anhydrous xylene replaced. The 4-lithium dibenzofuran then becomes fresh in the solvent at 24 g reacted distilled 6-ßrom-1-hexene at reflux temperature for 16 hours. The desired product is isolated by distillation; Bp 0.04 o4 145 ° C.

Example 7 4- (6-Heptsnyl) -dibenzofuran of the formula is manufactured according to the following procedure. 4-Lithium dibenzofuran is prepared by reacting 22 g of dibenzofuran in 200 ml of diethyl ether with 1.9 g of lithium and 16.5 g of butyl bromide in 50 ml of diethyl ether at 35 ° C. for 3 hours.

The diethyl ether is then replaced by an equal amount of anhydrous xylene replaced. The 4-lithium dibenzofuran then becomes fresh in its solvent at 27 g distilled 7-bromo-1-heptene reacted at reflux temperature for 16 hours. The desired product is isolated by distillation; Bp 0.04 = 150 ° C.

Example 8 4- (22-Tricosenyl) -dibenzofuran of the formula is prepared according to the following procedure: 4-Lithium dibenzofuran is prepared by reacting 22 g of dibenzofrunan in 200 ml of diethyl ether with 1.9 g of lithium and 16.5 g of bromide in 50 ml of diethyl ether at 35 ° C. for 3 hours. The diethyl ether is then replaced by an equal amount of anhydrous xylene. The 4-lithium dibenzofuran is then reacted in its solvent with 60 g of 23-bromo-1-tricosene at the reflux temperature for 16 hours. The desired product is isolated.

Example 9 4- (10-Phenyl-10-undecenyl) -dibenzofuran of the formula is manufactured according to the following procedure. 4-Lithium dibenzofuran is prepared by reacting 22 g of dibenzofuran in 200 ml of diethyl ether with 1.9 g of lithium and 16.5 g of butyl bromide in 50 ml of diethyl ether at 35 ° C. for 3 hours.

The diethyl ether is then anhydrous by an equal amount Xylene replaces b The 4-Lithiumdibenzofuran is then used in its solvent 32 g of 2-phenyl-11-bromo-1-undecene reacted at reflux temperature for 16 hours. The desired product is isolated.

The above examples clearly show that the new class of dibenzofuren derivatives according to the invention can be produced easily, simply and efficiently. The inventive Compounds include alkenyl substituted dibenzofurans, for. which are the alkenyl substituents Have carbon chain lengths between 2 and 23 carbon atoms. The substitutes themselves can be unsubstituted or they can be substituted by alkyl, aryl or substituted Alkyl or substituted aryl radicals in one or more suitable positions be substituted, as already stated.

These new compounds are able to reduce their double bonds React formation of a new class of polymers, with homopolymers, Copolymers, block copolymers and the like. Can be formed. Besides that vegen them with other chemical compounds through the aromatic nucleus and theirs Reacting double bonds, whereby new chemicals can be produced, which are suitable for use in pharmaceutical products, fungcides, insecticides, Soak dyes and other chemicals and products.

It can be seen that the method according to the invention is used different reaction times, temperatures and reaction media are carried out can to prepare the compounds according to the invention. The respective special Working method, through which the alkenyl substituents in the dibenzofuran ring are introduced depends on the chain length of the substituent.

The method according to the invention. that is simply »effective and rapid, delivers the compounds according to the invention in a relatively high yield and in a reproducible manner.

Claims (1)

P atent claims 1. Organic compositions containing a compound of the formula contain, in which n represents a value from 0 to 21 and R, R 'and R "each represent a hydrogen atom or an aryl, alkyl, substituted aryl or substituted alkyl substituent, 2. New compounds of the formula wherein n, R, R 'and R "have the meanings given above. 3. A compound according to claim 2, for which n is 1 or a Represents value from 3 to 21. 4. A compound according to claim 2, for which n represents the value 2. 5. 4-vinyldibenzofuran (formula 1 6. 4- (3-butenyl) dibenzofuran of the formula 7. 4- (4-pentenyl) dibenzofuran of the formula 8. New compounds of the formula wherein n has the meaning given above. 9. 4- (5-hexenyl) dibenzofuran of the formula '10. 4- (76-Heptenyl) -dibenzofuran of the formula 11. 4-Allyldibenzofuran of the formula 12. 4-Methallyldibenzofuran of the formula 13. Process for the preparation of 4-alkenyl-substituted dibenzfourans of the general formula in des n is a value from 0 to 21 and, R "and R" each denote a hydrogen atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent, characterized in that an alkali dibenzofuran of the formula wherein X is a sodium, potassium or lithium atom, under anhydrous, non-oxidizing conditions with an alkeny, 1 substituent of the formula in which n, R, R 'and R "have the meanings given above or converts a substituent which can be converted into such a substituent into a substitution with the alkali atom and, optionally after converting the substituent introduced into an alkenyl substituent of the formula given above, the 4 formed -alkenyl-substituted dibenzofuran wins. 14. The method according to claim 13, characterized in that for the preparation of 4-vinyidibenzofuran, the 4-alkali-substituted dibenzofuran is reacted with acetaldehyde, the product obtained is hydrolyzed and then the secondary alcohol formed of the formula is followed dehydrated to form 4-vinyldibenzofuran. 15. The method according to claim 14, characterized in that as Alkalidibenzfouran uses 4-lithium dibenzofuran and the dehydration of 4- (1-hydroxyethyl) dibenzofuran in the presence of a dehydration catalyst containing KHSO4 at about 180 ° C undertakes. 16. The method according to claim 13, characterized in that for the preparation of 4-butenyldibenzofurans, the 4-alkali-substituted dibenzofuran with a 1,4-dihalogenated butane of the formula in which R, R ', R ", R" 8 and R "" each represent a hydrogen atom or an alkyl, aryl, substituted alkyl or substituted aryl substituent and the radicals Ar, which can be the same or different from one another, are chlorine, bromine or iodine atoms, reacted and then under anhydrous, non-oxidizing conditions from the monohalogenated butyldibenzofuran of the formula wherein the various symbols have the meanings given above, to form a compound of the formula where the various symbols have the meanings given above, splitting off hydrogen halide in the presence of a hydrogen halide splitting catalyst, or converting the monohalogenated butyldibenzofurna formed into an amine, oxidizing it and pyrolyzing the amine oxide formed. 17. The method according to claim 16, characterized in that as Alkalidibenzofuran 4-sodium dibenzofuran used as a hydrogen halide elimination catalyst for the elimination of hydrogen halide from the monohalogenated butyldlbenzofuran a potassium tert-butoxide containing catalyst used and the reaction in about the reflux temperature. 18. The method according to claim 13, characterized in that for the preparation of dibenzofurans for which n represents the value 1 or a value from 3 to 21, the 4-alkali-substituted dibenzofuran with a monohalogenated alkene of the formula wherein n 'represents 1 or a value from 3 to 21 and the other symbols have the meanings given above, to an alkenyl-substituted dibsenzofuran of the formula wherein the various symbols have the meanings given above, implemented. 19. The method according to claim 18, characterized in that as 4-alkali dibenzofuran 4-lithium dibenzofuran used. 20. The method according to claim 19, characterized in that one the 4-lithium dibenzofuran is reacted with allyl chloride to form 4-allyldibenzofuran. 21. The method according to claim 19 »characterized in that the 4-Lithiumdibenz'ofuran is reacted with methallyl chloride to form 4-methallyldibenzofuran. 22. The method according to claim 19, characterized in that the Reacts 4-lithium dibenzofuran with 5-bromo-1-pentene to pentenyl) dibenzofuran. 23. The method according to claim 19, characterized in that the Reacts 4-lithium dibenzofuran with 6-bromo-1-hexene zr 4- (5-hexenyl) -dibenzofrunan. 24. The method according to claim 19, characterized in that the obtained 4-lithium dibenzofuran with 7-bromo-1-heptene to give 4- (6-heptenyl) -dibenzofuran implements.