DE1150059B - Process for the production of nitroacetals - Google Patents

Description

Process for the production of nitroacetals The invention relates to a process for the production of nitroacetals. In particular, the invention relates to nitroacetals of the general formula Herein R is hydrogen or an alkyl radical, R is hydrogen or an alkyl radical, R? is hydrogen, alkyl, halogen, nitroalkyl, nitro-aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl or nitrozaalkyl radical. R3 is a hydrogen, alkyl, halogen, nitroalkyl, nitro-aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl or nitrazaalkyl radical, which can be the same as R2 or different from R2, and A is an alkylene radical .

The nitroacetals produced by the new process and especially the geminal dinitroacetals are excellent plasticizers in the production of polyurethane binders for high-energy solid rocket propellants. The acetals are also suitable as plasticizers for nitrocellulose and nitropolymers. Because of their high nitro content, the plasticizers listed contribute to the energy of the propellant to which they are added, and - they are therefore superior to the plasticizers currently available on the market due to the fact that these commercial products contain no nitro groups and are accordingly essentially not energetic . In addition, the nitroacetals made by the process of this invention are also compatible with polyurethane systems in which the monomers contain geminal dinitro or nitroza groups and with which systems almost all currently commercially available plasticizers are incompatible.

The use of these nitroacetals as plasticizers in the polymerization of nitro polymers can be carried out in such a way that the polymerization is carried out together with the plasticizer or the plasticizer is mixed with the nitro polymer after the polymerization. The plasticizers are added to the nitro polymers, preferably in amounts of 10 to 400%, based on the total weight of the mixture. When acetals are used as plasticizers for polyurethanes without nitro groups, the same technique is used for the addition as for nitro polymers. The plasticizers are preferably added in an amount of about 150/0 based on the total weight.

The nitro-substituted polyurethanes can be used as primary power sources for missile propelled vehicles as well as propellants for artillery shells be used. When used as the primary power source for rocket vehicles they can be ignited in a known manner with a conventional ignition means. The drive means is preferably cast in a tubular shape and in the conventionally limited with a relatively inert resin. As such, it can't nitrided polyurethane foam or a polyester resin can be used. The drive means is placed in a chamber that is open on one side and in a conventional one Venturi rocket nozzle ends. After ignition, large amounts of gas are evolved ejected the nozzle, thereby generating the driving force.

The new process of this invention consists in the reaction of an aldehyde or a ketone with a nitro alcohol according to the general equation wherein R, Ri, R2, 1Z3 and A are defined as described above.

It can be seen that a large number and variety of connections within the scope of this invention and the method described therein by simply reacting a suitable aldehyde or ketone with a suitable one Nitro alcohol can be represented. For example of aldehydes and ketones, which are useful as reactants for this new process are the following: Isobutyraldehyde, isopentanaldehyde, 2-methyl-butyraldehyde, 2-methylpentanaldehyde, 3-methylpentanaldehyde, 2-methylcaproaldehyde, 2-ethylcaproaldehyde, enantaldehyde, 2-Äthylenantaldehyd ', 2-Isopropylenantaldehyd ,. Methyl isopropyl ketone, methyl isobutyl ketone, Ethyl isobutyl ketone, ethyl hexyl ketone, ethyl isohexyl ketone, diisopropyl ketone, dibutyl ketone, Diethyl ketone and methyl octyl ketone.

Examples of nitro alcohols useful as reactants for the process of this invention are as follows: 4-nitraza-2-nitrone-pentanol, 4-nitraza-2-chloro-n-pentanol, 4-nitraza-2-phenyl-methyl -n-pentanol, 4-chloro-2-methyl-2-nitro - n - butanol, 4 - cloro - 2,2 - dinitro - n - butanol, 4-chloro-2-cyclohexyl-2-nitro-n-butanol , 2-nitro-2-p-tolyl-n-hexanol, 2,5-dinitro-2-p-tolyl-n-pentanol , 2-chloro-2-nitro-2-phenylpropanol, Y, 3-dinitro-3 -phenylpropanol and 3 ', 3-dinitro-1-butanol.

It is within the scope of this invention to use as a starting material for the above reaction scheme used the aldehyde or the ketone to be shown in place. It can therefore be a more polymeric compound, which leads to a suitable aldehyde or Ketone depolymerizes the system together with a suitable depolymerization catalyst be admitted. For example, paraformaldehyde can be a polymer of formaldehyde along with a depolymerization catalyst that prevents breakdown and causing formaldehyde to form in place. In In the same way, paraldehyde can be a trimer of acetaldehyde in place depolymerized, with acetaldehyde being supplied for the new reaction.

All known depolymerization catalysts that are suitable for Such reactions are suitable for the formation of aldehydes or ketones Can be used in place in the manner described above. For this Purpose are especially the conventional acid esterification catalysts, such as sulfuric acid, Ferric chloride, p-toluenesulfonic acid, m-benzene disulfonic acid, zinc chloride, hydrochloric acid, Hydrofluoric acid, boron trifluoride, boron trifluoride complexes, etc. are suitable.

The reaction of this invention is preferably carried out in an inert solvent carried out. Any organic solvent known per se that can be used for this suitable, such as benzene, toluene, chloroform, carbon tetrachloride, methylene chloride, Ethylene dichloride, etc., are used as the reaction medium for the reaction of this invention useful. Although the use of an organic solvent as the reaction medium is preferable, it is within the scope of this invention to carry out the reaction in any another suitable fluid that is compatible with the system. So z. B. an excess of a reactant such as 2,2-dinitropropanol or a liquid catalyst, such as sulfuric acid, containing small amounts of water can be used. For practical purposes it is preferable to respond to this To carry out the invention in the presence of a catalyst. The above for education of aldehydes and ketones described on the spot may be suitable in the same way for the original reaction of our invention be. Consequently, for the on-site depolymerization the same material that catalyzes the new reaction can be used. aside from that are compounds which are generally suitable for the formation of alcoholates, e.g. B. Calium chloride, useful as catalysts for the reaction in this invention.

The reaction time is not critical for the implementation of the new method. The only visible effect of increasing or decreasing the temperature is a corresponding increase or decrease in the rate of the reaction. Although the reaction temperature is not critical, it is suggested that the practice of this invention use a temperature within the range of 20 to 50 ° C for reasons of process economy and tradition.

In order that this invention may be better understood, the following examples are given. However, they should only be taken as a means of explanation. The invention is not limited by these particular embodiments and the conditions described therein. Example I Preparation of formaldehyde bis (2,2-dinitropropylacetal) A 100 ml flask fitted with a thermometer and stirrer is filled with 15 ml of ethylene dichloride, 80.0 g of 2,2-dinitropropanol (0.50 mol, 93% 6% pure) and 19 ml concentrated (96%) sulfuric acid are added. Mixing takes place with a low level of exotherm and using moderate cooling. At 20 to 25 ° C. 7.8 g (0.24 mol) of paraformaldehyde (91 % flakes) are added, causing a weak exothermic reaction. The temperature is kept below 30 ° C. by cooling and continued at 25 to 30 ° C. for 1 hour. The upper layer is separated off with the aid of methylene chloride and the reaction mixture is extracted again with the same solvent. The organic phase is washed twice with dilute sodium hydroxide solution and twice with water and dried over sodium sulfate. The solvent is removed in vacuo and leaves behind 66.7 g (90% of theory) of a viscous, colorless liquid niD ' 1.4637.

40 g of the crude acetal are dissolved in 100 ml of denatured ethyl alcohol and seed crystals are added at 12 ° C. The mixture is cooled to -20 ° C. and the colorless product is filtered off, washed and dried. The yield is 30.2 g (76%).

Elemental analysis of a sample recrystallized twice from methanol (melting point: 32.5 to 33.5 - C), C7H12N4010: Calculated ... C 26.93%, H 3.87%, N 17.950 / 0, found: ... C 27.41%, H 3.74%, N 17.950 / 0, C 27.28%, H 3.75%, N 18.22 () / o. Example II Preparation of acetaldehyde bis- (2,2-dinitropropyl) acetal 1/10 mole of 2,2-dinitropropanol (15.8 g), 4.0 g of calcium chloride (0.036 moles, A. R. about 10 stitches per cm) and 2.2 g of acetaldehyde (0.050 mol) are mixed in a 50 ml round bottom flask. The bottle is closed with a stopper and the same is fastened so that it does not come off in order to prevent evaporation of the acetaldehyde. Most of the calcium chloride will gradually go into solution. After isolation of the crude acetal by the method described in Example 1 , 7.6 g (46% of theory) of a colorless oil n 21 1.4588 remain. The acetal is purified by recrystallization from diisopropyl ether, yield 4.2 g (26 () / o) n 21 1.4604. D Example III Preparation of Acetaldehyde-bis- (2,2-Dinitropropyl) -acetal This is a description for the preparation of Acetaldehyde-bis- (2,2-dinitropropyl) -aceta # in which the acetaldehyde starting material is in place from paraldehyde and an excess of sulfuric acid is used as the reaction medium.

A 50 ml three-necked flask equipped with a stirrer, thermometer and dropping funnel is mixed with 31.5 g (0.20 mol, 95.2% pure) 2,2-dinitropropanol and 15 ml concentrated sulfuric acid (96%). 4.4 ml (0.10 mol as acetaldehyde) of paraldehyde are added dropwise to this clear, colorless solution with thorough stirring. During the 10-minute addition period, the temperature is kept between 0 and -5'C. The mixture is stirred under O'C for 1 hour, the color gradually changing to an orange-brown. The apparently homogeneous reaction mixture is extracted twice with a total of 120 ml of methylene chloride. The extracts give 3.7 g (11% of theory) of a slightly brown-colored oil n1D1 1.4638. Example IV Preparation of acetaldehyde bis- (2,2-dinitropropyl) acetal This example describes the preparation of acetaldehyde - bis - (2,2 - dinitropropyl) - acetal by reaction of acetaldehyde, which is formed in place of paraldehyde , with 2,2-dinitroptopanol in methylene chloride as the reaction medium.

A 100 ml flask is mixed with 15.8 g (0.10 mol, 95% pure) 2,2-dinitropropanol, 25 ml methylene chloride, 3 drops of concentrated sulfuric acid and 2.2 ml (0.050 mol) paraldehyde. The mixture is then refluxed for 21 hours and about 0.5 ml of water (55% of theory) is removed azeotropically. The solution turns very dark brown. The crude acetal is isolated by washing the reaction mixture first with sodium hydroxide solution and then with water, drying the organic phase and removing the solvent in vacuo. A dark brown oil which weighs 6.8 g (42% of theory) of n-'D5 1.4625 remains as the residue.

Example V Preparation of acetaldehyde bis (2,2-dinitropropyl) acetal A glass pressure vessel is placed in ice and filled with 16 g (0.10 mol. 96% pure) 2,2-dinitropropanol, 4 g powdered calcium chloride and 2 , 2 g (0.050 mol) of acetaldehyde are added. The jar is closed with a rubber stopper that is firmly attached to prevent evaporation of the acetaldehyde. The mixture is shaken vigorously at the beginning and left to stand at room temperature for the next 6 days and shaken twice a day. The contents of the bottle are then poured into ice water, which contains 1.6 g of sodium hydroxide, and the crude product is separated off with the aid of methylene chloride. The organic solution, and finally washed first with 20 ml of 1N sodium hydroxide solution, then with 40 ml of 10% sodium bisulfite solution previously neutralized with sodium carbonate twice with water. The solution is dried and the solvent is removed in vacuo. The viscous, slightly green colored residue weighs 3.9 gn 2.1 D 1.4588. The vacuum distillation gives a first run at 110 to 165 ° C. and 0.45 mm and a clear yellow residue of 2.6 g (16% of theory) n11) 1 1.4609. The distillation of part of this residue from a retort in an oil bath at 0.3 to 0.4 mm and a temperature of 170 to 190 ° C. gives an almost colorless liquid 1121 D 1.4607. The infrared spectrum (IR spectrum) is identical to that of a known sample of acetaldehyde bis (2,2-dinitropropyl) acetal. Example VI Preparation of acetone bis (2-nitrobutyl) acetal Acetone bis (2-nitrobutyl) acetal is prepared by the method described in Example IV by reacting acetone with 2-nitrobutanol in the presence of ferric chloride as a catalyst. Example VII Preparation of n-butyraldehyde bis (2-chloro-2,4,4-trinitro-1-butyl) acetal N-butyraldehyde-bis (2-chloro-2,4,4-trinitro-1-butyl) Acetal is prepared by the method described in Beispie1V by reacting n-butyraldehyde with 2-chloro-2,4,4-trinitro-1-butanol in the presence of p-toluenesulfonic acid as a catalyst.

Example VIII Preparation of methyl n-butyl-ketone bis (5,5-dinitro-5-phenyl-1-phenyl) acetal Methyl-n-butyl-ketone-bis- (5,5-dinitro-5-phenyl-1-pentyl) -acetal is according to the in above examples described method by reaction of methyln-butyl-ketone with 5,5-Dinitro-5-phenyl-1-pentanol in the presence of m-benzene disulfonic acid as a catalyst manufactured.

Example IX Preparation of ethyl isopropyl ketone-bis- (2-nitro-4-phenyl-2-n-propylphenyl-l-butyl) acetal ethyl - isopropyl - ketone - bis - (2 - nitro - 4 - phenyl 2-n-propyl-phenyl-1-butyl) -acetal is prepared according to the method described in the above examples by reacting ethyl isopropyl ketone with 2-nitro-4-phenyl-2-n-propylphenyl-1-butanol in the presence made of zinc chloride as a catalyst.

Example X Preparation of formaldehyde bis (3-nitro-3-cyclohexyl-5-bromo-1-pentyl) acetal Formaldehyde bis (3-nitro-3-cyclohexyl-5-bromo-1-pentyl) acetal is produced according to the in the above-described method by reacting formaldehyde or one of its polymers with 3-nitro-3-cyclohexyl-5-bromo-1-pentanol.

Example XI Preparation of propionaldehyde bis (7-aza-5,5,7-trinitro-3-octyl) acetal # ropionaldehyde-bis- (7-aza-5,5,7-thiinitro-3-octyl) -acetal is according to the above Examples described method by reacting propionaldehyde with 7-aza-5,5,7-trinitro-3-octanol prepared.

Example XII Preparation of acetaldehyde bis (2,2,2-trinitroethyl) acetal Acetaldehyde bis (2,2,2-trinitroethyl) acetal is made according to the above examples method described by the reaction of acetaldehyde with 2,2,2-trinitroethanol.

Example XIII Preparation of acetaldehyde bis (2,2,4,4-tetranitro-n-pentyl) acetal Acetaldehyde bis (2,2,4,4-tetranitro-n-pentyl) acetal is prepared according to the method described above Examples given method by reaction of acetaldehyde with 2,2,4,4-tetranitro-n-pentanol manufactured.

The β-nitro alcohols used as starting material in this invention are prepared by reacting the corresponding α-nitroalkanes with formaldehyde, according to the well-known Henry reaction. The common dinitro alcohols, such as 2,2-dinitroethanol, are preferably obtained by acidifying the corresponding alkali metal salts according to the method described by Duden and Pondorff in Reports 38, 2031 (1905). 2,2,4,4-Tetranitrobutanol can be prepared by acidifying a salt of dinitroethanol. The free alcohol is obtained from the 2,2,4,4-tetranitrobutanol salt formed by adding acid.

The primary nitro alcohols (other than fl-nitro alcohols) which can be used as reactants for this process are prepared by reducing the corresponding acyl halides with sodium borohydride. The 4,4-dinitro-1-alkanol which can be used as a reactant for this new process is produced by selective reduction of Michael adducts, which are then reduced to the desired dinitro alcohols. A detailed description of this process can be found in Shechter et al. In J. Am. Chem. Soe., 74, 3664 (1952), and Feuer et al in J. Am. Chem. Soc., 77, 5740 (1955). 3,3-Dinitro-1-alkanol is produced by reacting the corresponding primary amine with nitrous acid to form unstable diazo compounds. In the decomposition of these diazo compounds, the desired alcohols are obtained in addition to gaseous nitrogen. A more detailed description can be found in Herzog, inter alia, in J. Org. Chem., 23, 1809 (1958).

The secondary nitroalcohols used as reactants in this invention are prepared by the selective reduction of ketones with sodium borohydride. The ketones are obtained by the well-known Michael addition of alkyl vinyl ketones, such as methyl vinyl ketone, to compounds with active hydrogen. The method is described in detail on page 484 of "Advanced Organic Chemistry" by Fuson, John Wiley & Sons, Inc. (1950).

It can be seen that a great number and variety of acetals within the scope of this invention by reacting appropriate starting materials can be represented by the method described above.

Mixtures of reactants can be used in the practice of the invention this new method can be used, and it is therefore within the scope of this invention Represent acetals with mixed alkoxy groups. For example you can in the field of this invention an aldehyde or a ketone, such as. B. acetaldehyde, with a Mixture of nitro alcohols, such as a mixture of 2,2,2-trinitroethanol and 2-chloro-2-nitroethanol let react, and you get a product with mixed alkoxy groups, such as acetaldehyde, 2,2,2-trinitroethyl-2-chloro-2-nitroethyl-acetal.

It will be apparent that the novel nitroacetals of this invention are either acetals or ketals, depending on the nature of the radicals R and Ri of the general formula. However, all of these new compounds are generically described and identified herein as acetals, in accordance with normal practice used in the literature. This practice has been recognized and followed by the Chemical Abstracts, as can be seen in the 299th section of the publication The Naming and Indexing of Chemical Compounds by Chemical Abstracts. This document is available from the Office of Chemical Abstrats, The Ohio State University, Columbus, Ohio. ,

Claims (1)

PATENT CLAIMS: 1. Process for the production of nitroacetals, characterized in that for the production of nitroacetals of the general formula a compound of the general formula with a nitro alcohol of the general formula is reacted, in which R is a radical selected from the group consisting of hydrogen and alkyl radicals, R is a radical selected from the group consisting of hydrogen and alkyl radicals, R2 is a radical selected from the group consisting of hydrogen, alkyl, halogen, nitroalkyl, Nitro, aryl, alkylaryl, arylalkyl, cycloalkyl, haloalkyl and nitrozaalkyl radicals, R3 is a radical selected from the group consisting of hydrogen, alkyl, halogen, nitroalkyl, nitro, aryl, alkyl-aryl, Arylalkyl, cycloalkyl, haloalkyl and nitrazaalkyl radicals and A is an alkylene radical. 2. - The method according to claim 1, characterized in that the reaction is carried out in the presence of an acidic esterification catalyst. 3. A process for the preparation of acetaldehyde bis (2,2-dinitropropylacetal) according to claim 1 and 2, characterized in that acetaldehyde is reacted with 2,2-dinitropropanol in the presence of sulfuric acid. 4. A process for the preparation of formaldehyde bis (2,2-dinitropropyl) acetal according to Claim 1 and 2, characterized in that formaldehyde is reacted with 2,2-dinitropropanol in the presence of sulfuric acid.