DE1094759B - Process for the cleavage of alkali-soluble condensation products from aromatic hydroxy compounds and aldehydes or ketones into their starting compounds - Google Patents

Description

Process for the cleavage of alkali-soluble condensation products from aromatic hydroxy compounds and aldehydes or ketones into their starting compounds In the condensation of aromatic mono- or polyhydroxy compounds with aldehydes or ketones in the presence of water-binding agents become phenolic compounds obtained in which two or more of the aromatic hydroxy compounds are attached to alkylidene radicals are bound. So z. B. from phenol and acetone mainly 2,2- (4,4'-dihydroxydiphenyl) propane. In addition, however, compounds are also formed in which the condensation of the phenol has not occurred in the 4-position, but in which an ortho hydrogen atom was split off. These asymmetrically built dihydroxydiphenylpropanes can in addition, just like the 2,2- (4,4'-dihydroxydiphenyl) propane, with acetone and Condense phenol or further dihydroxydiphenylpropane to give polyhydroxy compounds. The condensation also produces small amounts of non-alkali-soluble Compounds that are believed to have a pyran structure. Similar reaction mixtures arise quite generally during the condensation of aromatic mono- or polyhydroxy compounds with aldehydes or ketones.

The composition of the condensation products depends on the nature of the reactants, their proportions in the reaction mixture and on the condensation agent and especially on the reaction temperature, because the condensation products of aromatic mono- or polyhydroxy compounds with aldehydes or ketones are not stable at higher temperatures, but cleave into aromatic hydroxy compounds and alkenyl phenols. So split z. B. the condensation products of phenol and acetone in phenol and isopropenylphenol. The alkenylphenols are also not stable at the temperatures at which they are formed; instead, through confusing polymerization and disproportionation reactions, they form resinous compounds, and in some cases also alkylphenols. So you get z. B. when distilling 2,2- (4,4'-dihydroxydiphenyl) -propane under atmospheric pressure about 50 "/, phenol in addition to non-determinable resins and isopropylphenol. The cleavage temperature is lowered considerably by adding alkali or acid. B. the 2,2- (4,4'-dihydroxydiphenyl) propane in the presence of alkali or acid can be cleaved into phenol and polymerization products of isopropenylphenol at just over 100 ° C. These cleavage reactions proceed in a similar way in the presence of steam.

From USA. Patent 2,841,622 it is known to react with aliphatic alcohols dihydroxydiphenyl alkanes in the presence of alkali metal hydroxides at temperatures above 150 'C under pressure to give substituted in the 4-position phenols. Here, the alcohol reacts with a non-stable intermediate product formed as an intermediate from the cleavage of the bisphenol, so that 2 molecules of alkylphenols substituted in the 4-position result from each molecule of bisphenol. A cleavage of the bisphenol into the starting materials used for its production is therefore not possible by this process.

It is also known from German patent 570270 to recover part of the phenol used for their production from phenol-formaldehyde resins by heating these resins to temperatures of up to 440 ° C. under pressure in the presence of hydrogen-containing gases. Here, however, profound chemical changes take place in the starting materials, so that some of the reaction products consist of low-boiling compounds that can be used as motor fuel, another part, generally about 40 to 440 /, of the starting materials, consists of gaseous substances, viscous oils or pitch-like residues and the remainder consists of carbolic oil partially containing phenol.

Overall, only about 27 liters of phenol, based on the amount of starting materials, are obtained. Complete cleavage of condensation products from phenols and aldehydes into the starting materials is not possible even by this process.

It has now been found that alkali-soluble condensation products of phenols and aldehydes or ketones can be split almost completely into their starting compounds under pressure in the presence of basic compounds at temperatures between about 150 and 350 ° C. and especially between about 200 and 300 ° C. . No alkenylphenols or their polymers are formed. In the cleavage of condensation products from phenols and aliphatic ketones, further reactions by reacting the phenols with the oxo compounds are almost completely avoided. Condensation products of phenols with cycloaliphatic and aromatic ketones and with aldehydes, on the other hand, form varying amounts of resinous condensation products as by-products during the cleavage, which are also formed as by-products when the phenols are reacted with these oxo compounds.

According to the process of the invention, alkali-soluble condensation products of aromatic hydroxy compounds and aldehydes or ketones are converted into their starting compounds under pressure in the presence of basic compounds and water at temperatures between about 150 and 350 ° C., especially between about 200 and 300 ° C. split.

Alkali-soluble condensation products of phenols and oxy compounds which are cleaved by the process of the invention are, for. B. 1,1- (4,4'-dihydroxydiphenyl) - ethane, 4,4' Dihydroxytriphenylmethan, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenyhnethan, 2,2- (4, 4'-dihydroxydiphenyl) propane, 2,2- (4,4'-dihydroxy-3,3'-dirnethyldiphenyl) propane, 2,2- (4,4'-dihydroxydiphenyl) butane, 2,2- ( 4,4'-dihydroxydiphenyl) pentane, 2,2- (4,4'-dihydroxydiphenyl) -4-methylpentane, 3,3- (4,4'-dihydroxydiphenyl) pentane, 1,1- (4.4 '-Dihydroxydiphenyl) -cyclohexane, 2,2- (4,4'-dihydroxydiphenyl) -2-phenylethane and (4,4'-dihydroxydiphenyl) -diphenylmethane as well as the alkali-soluble aromatic di- and polyphydroxyl compounds with other chemical substances Construction.

For cleavage, those in the preparation of the polyhydroxy compounds can be used resulting crude products or the pure 4,4'-dihydroxypolyphenylalkanes or else the separated alkali-soluble by-products are used without affecting the yields the fission products are thereby significantly influenced.

Basic compounds suitable for the process are especially alkali and alkaline earth metal hydroxides and carbonates, also z. B. ammonia and basic ammonium salts.

The reaction can be carried out, for example, by dissolving the condensation products to be cleaved in dilute aqueous alkali and heating the solution in the pressure vessel to temperatures between about 150 and 320 'C, corresponding to pressures of about 5 to 150 atmospheres, until the Cleavage is complete. At temperatures around 300 'C this is z. B. in the case of the condensation products of acetone and phenol in about 30 minutes, at 240 ° C. in about 3 hours. The cleavage can advantageously also be carried out continuously.

It is then expedient to first distill the from the reaction mixture Oxo compounds from. Then neutralize the aromatic contained in the residue Hydroxy compounds and separates the resulting free hydroxy compounds Extract or distill off.

The process makes it possible in particular from the in the manufacture alkali-soluble by-products formed by 4,4'-dihydroxypolyphenylalkanes easily recover the starting compounds.

Example 1 * A homogeneous solution of 100 g of 2,2- (4,4'-dihydroxydiphenyl) propane, 5 g of caustic soda and 440 g of water is stirred for 3 hours at 240 ° C. at an initial pressure of 20 ° C. in a 11-capacity pressure vessel atü nitrogen heated, whereby the pressure rises to 70 atü. The alkaline solution is then cooled to 20 ° C. and distilled in a column, 23 g of acetone = 90.5 % of the theory being passed over. The residue is acidified to a p. Value of 5 with 500% phosphoric acid and the phenol is blown over with steam, giving 80.4 g of phenol = 97.5% of theory.

In a series of further experiments in the same way in each case 100 g of 2,2- (4,4'-dihydroxydiphenyl) propane are split with other basic compounds instead of caustic soda and the amount of phenol split off is obtained as above. The yields listed in the following table are obtained: Ab- yield Base water split into 0 /, the 1 phenol theory 49 g potassium hydroxide ... 4w g 82 5 g 100 46.5 grams of sodium carbonate . . 440 g 69: 3 g 84 31 g ammonium hydroxide 440 g 62.7 g 76 Example 2 To carry out the cleavage continuously at different residence times and different temperatures, a nickel tube coil heated in an oil bath and having a capacity of 600 ccm and an inner diameter of 8 mm is used, through which a solution of 100 g of 2.2- (4.4 '-Dihydroxydipheny) propane and 35 g caustic soda in 440 g water is pumped under the corresponding saturation pressure of the water vapor.

The reaction mixtures obtained are worked up as in Example 1. The results are summarized in the following table: Phenol, acetone, Temperature residence time yield in yield in Ol ', the 0 /, the Theory theory 2000 C 30 minutes 15.5 0 2000 C 60 minutes 29.5 16 2700 C 10 minutes 71 60 2700 C 30 minutes 93 83 2700 C 60 minutes 97.5 87.5 3000 C 10 minutes 80 79 3000 C 30 minutes 98.5 88.5 300 'C 60 minutes 99 89 Example 3 Under the same experimental conditions as in Example 1 , 100 g of the resinous compounds which were obtained and separated off as a by-product in the preparation of 2,2- (4,4'-dihydroxydiphenyl) propane by the process of German patent 1027205, heated under pressure with 35 g of caustic soda and 440 g of water. The yield of acetone is 19 g = 75 % of theory and of phenol is 68.5 g = 83 % of theory.

Example 4 As in Example 1 , a solution of 100 g of 2,2- (4,4'-dihydroxydiphenyl) pentane and 31.5 g of caustic soda in 395 g of water is heated to 240 ° C. under pressure for 4 hours. 29.5 g of methyl propyl ketone = 88 % of theory and 72.5 g of phenol = 98.7 % of theory are obtained.

Example 5 As in Example 1 , a solution of 100 g of 1,1- (4,4'-dihydroxydiphenyl) cyclohexane and 30 g of caustic soda in 375 g of water is heated to 240 ° C. under pressure for 5 hours. The resulting ketone is obtained from the alkaline solution by extracting it with benzene. The yield of cyclohexanone is 8 g = 21.9% of theory, of phenol 56.5 g = 80.7% of theory. Example 6 As in Example 1 , a solution of 100 g of 4,4'-dihydroxytriphenylethane and 28 g of caustic soda in 360 g of water is heated to 240 ° C. under pressure for 5 hours. The resulting acetophenone is extracted from the alkaline solution with benzene. The yield of acetophenone is the theoretical 19 g = 45.9 0/0 to Phenoi 45 g = 69.4% of theory.

Example 7 As in Example 1 , a solution of 100 g of 3,3 ', 5,5'-tetrainethyl-2,2'-dihydroxydiphenylmethane and 31 g of caustic soda in 380 g of water is heated to 240 ° C. under pressure for 5 hours. The organic layer which separates out during the neutralization is separated off and distilled. The yield of 2,4-dimethylphenol is 58 g = 79 "/, of theory.

Claims (2)

PATENT CLAIMS -1. Process for the cleavage of alkali-soluble condensation products from aromatic hydroxy compounds and aldehydes or ketones into their starting compounds, characterized in that the cleavage is carried out in the presence of basic compounds and water at temperatures between about 150 and 320 ° C. under pressure. 2. The method according to claim 1, characterized in that alkali-soluble 4,4'-dihydroxypolyphenylalkanes or the alkali-soluble by-products formed during their preparation are cleaved. Documents considered: German Patent No. 570 270; U.S. Patent No. 2,841,622 - Chemische Technik, Vol. 3, 1951, p. 8.