DE1083821B - Process for the preparation of ª ‡ -alkoxydialkyl peroxides - Google Patents

Description

Process for: Preparation of α-alkoxydialkyl peroxides The invention relates to a process for the preparation of a-Alkoxydialkylperoxden, which also as Monoperoxyacetals can be designated.

It is known that peroxides with an alkyl peroxide group in addition to one Ether group so far by exchanging an alkoxy group for an alkylperoxy group only in the case of the cyclic ether isochroman can be obtained, and that acetals are obtained in this way cannot be transacetalised under mild conditions.

It has been found that acetals of aldehydes of the general formula in which R1 is any aliphatic, aromatic radical and R2 is an alkyl radical, when heated with organic hydroperoxides of the general formula ROOH, in which R is an alkyl, cycloalkyl or aralkyl radical, with elimination of 1 mol of alcohol α-alkoxydialkyl peroxides (monoperoxyacetals) the general formula deliver. In this way, acetals can be transacetalized under mild conditions - heating to 60 to 80 "C for several hours is sufficient - quite generally and with excellent yields with alkyl hydroperoxides. The monoperoxyacetals obtained in this way have not yet been described in the literature. They are surprisingly stable liquids of acetal-like odor, which is relatively less explosive. The low molecular weight monoperoxyacetals can be distilled undecomposed in vacuo. Thus, the propionaldehyde-tertiary-butylperoxyacetal (1-ethoxy-1-tertiary-butylperoxypropane), which is easily obtainable from propionaldehyde-diethyl-butyl-acetal and tertiarydehyde-butyl-acetal, boils. at 41 to 43 ° C with a 24 mm Hg column.

The production of this monoperoxyacetal takes place according to the equation 1-Ethoxy-1-tert-butylperoxybutane (from butyraldehyde diethyl acetal and tertiary biltyl hydroperoxide) boils at 69 to 69.80 C with a 16 mm Hg column.

The compounds are resistant to dilute alkali, so that when using excess alkyl hydroperoxide, which is useful for the preparation, it can be extracted from the monoperoxyacetal with 2N sodium hydroxide solution. With dilute acids the monoperoxyacetals are split into the starting aldehyde, the alcohol and the alkyl hydroperoxide: Suitable aldehydes are all those which can form acetals. Suitable hydroperoxides are the previously known alkyl hydroperoxides; such as methyl, ethyl, propyl, tertiary butyl hydroperoxide, also benzyl, cyclohexene, tetrahydronaphthalene, decahydronaphthalene, cumyl hydroperoxide and the dihydroperoxide of diisopropylbenzene. The reaction is therefore capable of very versatile applications, as is also demonstrated by the following examples.

The new peroxides are easy and harmless to handle catalysts for the initiation of chain reactions z. B. for the polymerization of vinyl compounds.

Example 1 í-ethoxy-1-cumylperoxy-butane 14.6 parts of butyraldehyde diethyl acetal are used with 17; 3 parts of gumol hydroperoxide heated to 80 ° C. for 7 hours. Then it is extracted 5 times with 2N NaO H, washed with water, dried with Na2CO3 and concentrated to 90 ° C bath temperature at a pressure of 0.02 torr to remove the split off ethanol.

The peroxide does not remain as a weakly acetal-like smell distillable liquid that evaporates when overheated.

The yield is 17; 2j parts, that is 70,010 of theory. Of the Refractive index 74V1D8 is 1.4822.

Example 2 p-Nitrophenyl-methoxy-tert-butylperoxymethane 8.9 parts of p-nitrobenzaldehyde dimethyl acetal are heated with 4.5 parts of tertiary butyl hydroperoxide to a bath temperature of 80 ° C. for 10 hours. It is then extracted 4 times with 2N NaOH, washed with water, dried with Na2CO3 and concentrated in vacuo (0.02 torr) to a bath temperature of 65 ° C. What remains is a light yellow, oily liquid that cannot be distilled and which evaporates violently when overheated.

The yield is 8.9 parts, that is 78% of theory. Of the Refractive index nD19.7 is 1.5157.

Example 3 1-Ethoxy-1-cumylperoxy-heptane 6.6 parts of enanthaldehyde diethylacetal are heated with parts of cumene hydroperoxide to a bath temperature of 85 ° C. for 6.5 hours. It is then extracted 4 times with 2N NaOH, washed with water and concentrated in vacuo (0.03 torr) to a bath temperature of 80 ° C. The peroxide remains as an oily, clear liquid.

The yield is 7.3 parts, which is 840% of theory. The index of refraction n201 is 1.4816.

Example 4 1-Ethoxy-1-tertiary-butylperoxy-butane 14.6 parts of butyraldehyde diethylacetal are heated with 14.0 parts of 700i0igem tertiary butyl hydroperoxide in a water bath to a bath temperature of 80 ° C. for 6 hours. After cooling, it is extracted 4 times with 2N NaOH, washed with water and dried with Na2CO3. It is then distilled through a Vigoureux column.

Pure yield: 13 parts (69% of theory). The Kp.16 is 69 bis 69.8 ° C, the refractive index nD21 = 1.4082.

Example 5 1-Ethoxy-1-tertiary-butylperoxy-heptane 10.9 parts of enanthaldehyde diethylacetal are heated to a bath temperature of 80 ° C. for 10 hours with 6.5 parts of tertiary butyl hydroperoxide. Then it is extracted 4 times with 2N NaOH, washed with water and, after adding an equal volume of ether, dried with Na2CO3 and fractionally distilled.

The yield of pure peroxide was 9.2 parts, that is 7001o Theory. The bp 0.03 is 45 to 46.5 ° C, the refractive index nD19.7 is 1.4208.

Example 6 Phenyl-ethoxy-tert-butylperoxy-methane 13.6 parts of benzaldehyde diethyl acetal are heated to a bath temperature of 80 ° C. for 8 hours with 6.75 parts of tertiary butyl hydroperoxide. It is then extracted 4 times with 2N NaOH, washed with water and concentrated in vacuo to a bath temperature of 80 ° C. It. what remains is a colorless, oily liquid that smells faintly acetal.

The yield is 12.3 parts, that is 73% of theory. The refractive index nD21 is 1.4814 Example 7 1-Ethoxy-1-tert-butylperoxypropane 10.7 parts of propionaldehyde diethylacetal are heated with 7.3 parts of tertiary butyl hydroperoxide to a bath temperature of 80 to 85 ° C. for 7 hours. It is extracted 3 times with 2N NaO H, washed with water, dried with Na2C03 and fractionated 3l is 670 C.

The yield is 12.8 parts, that is 89% of theory. The index of refraction nD20 is 1.4029.

Claims (1)

P A T E N T A N S P R U C H. Process for the preparation of α-alkoxydialkyl peroxides of the general formula characterized in that acetals of the general formula in which the radical of an acetal-forming aldehyde and R2 is an alkyl radical, reacted with organic hydroperoxides of the general formula ROOH, in which R is an aliphatic, cycloaliphatic or alkylaromatic radical, by heating for several hours at 60 to 800 C, at the same time expediently removing the split off alcohol R2O H, Any excess organic HydroperoxydRO OH is separated from the reaction mixture by extraction with dilute sodium hydroxide solution and the peroxides are recovered in a manner known per se. Publications considered: Koarnoj etzki, Les Peroxydes Organiques, 1958, pp. 68,69; Journal of the American Chemical Society, Vol. 76, 1954, Pp. 2323, 2324.