DE957569C - Process for the preparation of 1, 1, 3-triisopropoxyalkanes - Google Patents

Description

Process for the preparation of 1,1,3 -triisopropoxyalkanes In the main patent 94I 974 has been described to prepare I, I, 3-trialkoxyalkanes by one a "B-unsaturated aldehyde with an alcohol in the presence of an acidic one Reacts catalyst and a water entrainer and from the reaction mixture the water contained therein and formed by the condensation during the condensation reaction removed as an azeotropic mixture. An example is given in the main patent 94I 974, which the representation of I, I, 3-triisopropoxypropane by mixing 8 0 / o Acrolein containing water with isopropyl alcohol, which is concentrated hydrochloric acid contained as a condensation catalyst and methylene dichloride as an entrainer, describes.

The mixture was refluxed using a phase heated separating attachment, whereby the water was removed from the mixture, until the delivery of water stopped. The yield of I, I, 3-triisopropoxypropane produced in this way based on the acrolein used, was 28o.

It has now been found to be significant under certain conditions greater yields of tnisopropoxyalkanes can be obtained when as much water as possible is removed from the reaction mixture before the condensation is carried out.

Accordingly, the production of I, I, 3-triisopropoxyalkanes advantageously carried out so that an α, B-unsaturated aldehyde with isopropanol in the presence of a condensation catalyst and a water entrainer in the Reaction mixture reacted under practically anhydrous conditions and that through the condensation reaction azeotropically removes liberated water.

Under the expression "under practically anhydrous conditions" is to be understood that the present in the reaction mixture at the beginning of the reaction Amount of water less than weight percent of the unsaturated aldehyde, expedient less than 2 / o, and, most desirable, as little as possible ..

A preferred method of performing the method is to that first a mixture of the unsaturated aldehyde, isopropanol and the water entrainer It is distilled until no more water passes over azeotropically and then the condensation catalyst added to the mixture, which is then heated until no more water distills off. However, if any of the reactants is already anhydrous, that one can be used add after the remaining components have been freed from water.

The inventive method can be used with particular advantage on the lower a "B-unsaturated aldehydes, which contain I hydrogen atom in a-position, z. B. acrolein and crotonaldehyde can be used. However, the procedure is also for a, p-unsaturated aldehydes which have an alkyl substituent in this position have, such as a-methacrolein and a-ethyl acrolein, useful.

The condensation can be carried out in the presence of a polymerization inhibitor, z. B. hydroquinone, be made in the reaction mixture.

The usual condensation catalysts, for example sulfuric acid, hydrochloric acid, phosphoric acid, organic sulfonic acids, Boron trifluoride and its ethereal compounds, aluminum chloride, and also acid clays and acidic zeolites are used.

As an entrainment agent for the water can be used for the withdrawal use inert organic compounds known from water. Suitable for this Compounds are, for example, hydrocarbons such as benzene and toluene, chlorinated Hydrocarbons such as methylene dichloride and chloroform, and ethers such as isopropyl ether.

Suitable temperatures for carrying out the reaction are between 40 and 1000 and higher. They depend on the nature of the respondent, nature and the amount of entrainer and the pressure at which the reaction is effected will. The advantages of the present invention are particularly evident in those cases in appearance, in which, for economic reasons, the implementation in the higher temperatures within the stated range, e.g. B. at 600 and above, is made.

These conditions may arise, for example, when necessary is a relatively small amount of the entrainer or a cheaper entrainer with a higher boiling point to apply, and where it is impossible. keeping the temperature low by reducing the pressure.

The r, 1, 3-triisopropoxyalkanes prepared according to the invention can from the reaction mixture after neutralization of the condensation catalyst Distillation can be obtained.

This can e.g. B. in a simple fractionation under atmospheric pressure or under reduced pressure or first in a distillation or flash distillation with subsequent fractionation.

The 1, 1, 3-triisopropoxyalkanes are valuable foaming agents. The I, I, 3-triisopropoxybutane has not yet been described for the rest.

It is known to acetalize glycerine and thereby the formed Azeotropic removal of water. However, such acetalizations were not known in reactions of the type claimed, in which there is also an addition to the Double bond occurs, and it was not expected to happen just at the use of isopropanol results in the yields of alkoxy compounds would increase such.

The following examples are intended to explain the implementation of the serve the method according to the invention.

Example I 136 parts by volume 970 / o acrolein, which 112 parts by weight Acrolein contained 960 parts by weight of isopropyl alcohol, 800 parts by volume of methylene dichloride and 1.5 parts by weight of hydroquinone were thoroughly azeotroped drains. Then 4.19 parts by weight of anhydrous hydrochloric acid, which had been dissolved in 35 parts by volume of isopropyl alcohol, given. The mixture was heated and the water-methylene dichloride azeotrope with the help of a 1 m long Vigreux column, which with an attachment to siphon off the top layer and to Return of the lower layer was provided, distilled off until no water azeotrope more iiberging.

The reaction mixture was then washed with excess anhydrous Treated and fractionated sodium acetate. After removing the methylene dichloride and the excess of isopropyl alcohol was taking the residual liquid Distilled under reduced pressure without fractionation to remove them from inorganic salts to free. The distillate was then distilled.

I, I, 3-triisopropoxypropane was used as one at 890 under one pressure of 10.5 mm of mercury boiling fraction calculated in a yield of 790 / o on the applied acrolein.

The 2,4-dinitrophenylhydrazone of B-isopropoxypropionaldehyde was from the I, 1, 3-tri isopropoxypropane shown and from aqueous Recrystallized methyl alcohol. It was obtained in plates melting at 990.

Example 2 A mixture of 57.7 parts by weight of acrolein with a Content of 30/0 water and 0.110 / o hydroquinone, 480 parts by weight isopropyl alcohol and 600 parts by volume of methylene dichloride, plus 0.75 parts by weight of hydroquinone were added, was in one with a Vigreux column of 1 m length, which one Wore phase-separating attachment, which continuously siphoned off the upper aqueous layer and the lower layer, which was returned as reflux, was heated to the boiling point. The temperature in the reaction mixture was 480.

As soon as the formation of an aqueous phase in the essay ceased, The contents of the bladder were allowed to cool slightly and a solution of 2.39 parts by weight was then added anhydrous hydrochloric acid in 20 parts by volume of isopropyl alcohol to the mixture.

The azeotropic distillation started again and continued, until the delivery of water stopped. The reaction temperature was then 520.

The pale brown colored bladder contents were then after cooling, as described in Example 1, treated further. There were 176 parts by weight at 96.5 to 97.50 and a pressure of 16 mm Hg boiling I, I, 3-triisopropoxypropane obtained, which corresponds to a yield of 8i 8Io / o, calculated on the acrolein used, equals.

Example 3 A mixture of 57.1 parts by weight of acrolein (97 ovo pure), 300 parts by weight of isopropyl alcohol and 600 parts by volume of methylene dichloride 0.75 part by weight of hydroquinone was added. The mixture was as in the previous Example described, dehydrated, cooled slightly and anhydrous with 2.37 parts by weight Hydrochloric acid, which was dissolved in 20 parts by volume of isopropyl alcohol, was added. the Azeotropic distillation was started again and continued until no water more passed over.

The contents of the kettle were then cooled, as described in Example 1, treated further.

The yield of I, I, 3-triisopropoxypropane was 78 ° / n, calculated on the acrolein used, Example 4 A mixture of 57.1 parts by weight Acrolein (containing 2 percent by weight of water), 480 parts by weight of isopropyl alcohol, 600 parts by volume of methylene dichloride and 0.75 parts by weight of hydroquinone was how described in Example I, dehydrated.

After a little cooling, 3.2 parts by weight of sulfuric acid (specific Weight I, 84), dissolved in 16 parts by weight of isopropyl alcohol, was added.

Azeotropic distillation was carried out again and continued, until no more water passed over.

The boiler temperature was then 48 °.

The obtained product was gradually introduced into a vessel which a small excess of concentrated potassium hydroxide solution, calculated on the sulfuric acid used. It was then distilled to remove the methylene chloride and to recover isopropyl alcohol.

The remaining liquid was distilled without fractionation, to rid them of inorganic salts, and then fractionate the distillate. The yield of I, I, 3-triisopropoxypropane was 740/0.

Example 5 Repetition of Example 4 using only 0.64 parts by weight of sulfuric acid (specific gravity I, 84) as a catalyst, which were dissolved in 16 parts by weight of isopropyl alcohol, while the remaining quantities the reactants, with the exception of the potassium hydroxide, which accordingly was reduced, remained unchanged, gave a yield of I, I, 3-triisopropoxypropane from 870/0.

Example 6 Repetition of example 2 omitting the 0.75 Parts by weight of hydroquinone and using acrolein, which is the usual Amount of stabilizer contained, gave a yield of 8 I 0/0 ° / @ 1, 1, 3-triisopropoxypropane.

Example 7 Repetition of Example 2 using only 0.83 Parts by weight of anhydrous hydrochloric acid as a catalyst, which in 5.6 parts by weight Ise pyl alcohol were dissolved, gave 1, 1, 3-triisopropoxypropane in one yield from 840/6.

Example 8 A mixture of 78 parts by weight of moist crotonaldehyde, which contained 90.8 percent by weight crotonaldehyde, 600 parts by volume isopropyl alcohol, 600 parts by volume of methylene dichloride and 0.75 parts by weight of hydroquinone was under Using a 1 m long Vigreux column heated.

This latter was provided with a phase separating column attachment, which constantly siphoned off the upper aqueous layer of the distillate and the lower Recirculated layer as reflux in the columns. As soon as the water supply stopped, what happened after 30 hours, 15 parts by volume of a 3.2N solution of anhydrous Hydrochloric acid in isopropyl alcohol is added and the reflux condenser is reduced Separation of the water (a total of 14 parts by volume) continued for a further 53 hours. No more water was released during the heating for the last 5 hours.

The product was made with a solution of sodium isopropylate in isopropyl alcohol neutralized and distilled without fractionation. The distillate amounted to I32 parts by weight and boiled from 95 to 10000ki18 mm Hg. It was subsequently fractionated and gave 100 parts by weight of I, I, 3-triisopropoxybutane with the boiling point 88 to 890/9 mm Hg, which is 42.5 o / o of theory. The calculation coefficient was n2D n 1.4113 to 1.4113 to 1.4116, mainly 1.4113 to 1.4116.

The forerun contained another small amount of the triisopropoxybutane.

The 2,4-dinitrophenylhydrazone of the β-isopoxybutyraldehyde was prepared therefrom by converting a volume of triisopropoxybutane to a saturated Solution of 2,4-dinitrophenylhydrazine in 2N hydrochloric acid added and shaken. That The derivative was chromatographed on acid washed alumina in benzene solution ge cleansed and recrystallized from ethyl alcohol, woc with yellow leaflets from the melting point 102.5 were incurred.

Simultaneously with the 2,4-dinitrophenylhydrazone of ß-isopropoxybutyraldehyde was the 2,4-Ditrophenylhydrazone of crotonaldehyde in approximately the same amount formed by splitting off the isopropoxy group. The melting point of this hydrazone and its mixture with an authentic pattern was 189,0.

Example g A mixture of 173.2 parts by weight of acrolein (g7e / o pure), I800 parts by weight of isopropyl alcohol and 400 parts by volume of methylene dichloride was as described in Example I and 2, drained, then cooled and with 45 parts Isopropyl alcohol in which 5.4 parts by weight of anhydrous hydrochloric acid were dissolved, treated.

The azeotropic distillation was started again and continued, until no more water passed over. The reaction mixture was with an excess of treated with anhydrous sodium acetate and then, as described in Example I, worked up. There were 287.7 parts by weight of I, I, 3-triisopropoxypropane in one Yield of 446 / o obtained.

In a very similar approach, but in which the reagents had not been dehydrated before the addition of the acidic catalyst, the Yield of triisopropoxy compound only 28%.

PATENT CLAIM: I. Process for the preparation of I, I, 3-triisopropoxyalkanes in a further development of the method according to patent 941 974, characterized in that that one a, ß-unsaturated aldehyde with isopropyl alcohol in the presence of a Condensation catalyst and a water entrainer in the reaction mixture brings to action under practically anhydrous conditions and that by the Water released from the condensation reaction is removed azeotropically.

Claims (1)

2. The method according to claim I, characterized in that ger indicates that the The reaction continues until no more water is released by condensation is, whereupon the I, I, 3-triisopropoxyalkane is isolated from the reaction mixture. 3. The method according to claim I and 2, characterized in that the Reaction mixture contains less than 2e / o water at the beginning of the condensation reaction. 4. The method according to claim I to 3, characterized in that the a, ß-unsaturated aldehyde is acrolein or crotonaldehyde. 5. The method according to claim I to 4, characterized in that one the condensation reaction in the presence of a polymerization preventive agent carried out in the reaction mixture. 6. The method according to claim I to 5, characterized in that the The condensation catalyst is a strong mineral acid. 7. The method according to claim I to 6, characterized in that the Reaction at temperatures between 40 to 1000 is effected. Publications considered: Comptes Rendus 2I4 (1942), pp. 359, 360.